tag:theconversation.com,2011:/us/topics/materials-1306/articlesMaterials – The Conversation2024-03-22T12:31:50Ztag:theconversation.com,2011:article/2201902024-03-22T12:31:50Z2024-03-22T12:31:50ZThin, bacteria-coated fibers could lead to self-healing concrete that fills in its own cracks<figure><img src="https://images.theconversation.com/files/578396/original/file-20240227-26-c98ze5.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C5176%2C3437&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cracked roads and sidewalks generate big costs for cities. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/CaliforniaDroughtRain/f93eda16ae2d49ad8539aaf1ad9eb92c/photo?Query=cracked%20concrete&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=260&digitizationType=Digitized&currentItemNo=17&vs=true&vs=true">AP Photo/Marcio Jose Sanchez</a></span></figcaption></figure><p>Some say there are two types of concrete – cracked and on the brink of cracking. But what if when concrete cracked, it could heal itself? </p>
<p><a href="https://research.coe.drexel.edu/caee/aim/">We’re part of a team</a> of <a href="https://scholar.google.com/citations?user=Tn72mFcAAAAJ&hl=en">materials</a> <a href="https://scholar.google.com/citations?user=AtY08c4AAAAJ&hl=en">scientists</a> and microbiologists that has <a href="https://theconversation.com/calcium-munching-bacteria-could-be-a-secret-weapon-against-road-salt-eating-away-at-concrete-roads-and-bridges-113970">harnessed the power of bacteria</a> to create biological fibers that <a href="https://doi.org/10.1016/j.conbuildmat.2023.133765">initial results suggest</a> can heal cracks in concrete. We’re working on a technology that, if we work out the kinks and manage to bring it to the market one day, could extend the life span of concrete.</p>
<h2>Cracking concrete</h2>
<p>Picture a bridge exposed to snow, rain, temperature changes and trucks carrying heavy loads. The concrete on the bridge will gradually develop cracks from stress and wear. Over time, these cracks expand, allowing water and corrosive substances that weaken the concrete to penetrate further down. </p>
<p>At some point, local authorities have to pay for repairs, which are not only expensive but also <a href="https://artbabridgereport.org/reports/2022-ARTBA-Bridge-Report.pdf">disrupt traffic and drain public resources</a>.</p>
<p>Now, consider a medical patient recovering from a severe injury. As the patient’s cells recognize the damage, they release tiny healing agents – like microscopic repair crews. These agents target the wounded area, mending tissues and restoring the cells’ functionality. What if concrete had the same kind of <a href="https://doi.org/10.1038/nmat1934">self-healing ability</a> as human tissue? </p>
<h2>A self-healing concrete</h2>
<p><a href="https://research.coe.drexel.edu/caee/aim/people/">Our team</a> at the <a href="https://research.coe.drexel.edu/caee/aim/">Advanced Infrastructure Materials lab</a> at Drexel University was inspired by self-healing tissue in the human body. We developed an addition to concrete we <a href="https://doi.org/10.1016/j.conbuildmat.2023.133765">call BioFiber</a>.</p>
<p>BioFiber has <a href="https://doi.org/10.1016/j.conbuildmat.2023.133765">three essential functions</a>: It heals itself on its own, it stops cracks from growing wider, and it remains intact inside the concrete when there aren’t any cracks. </p>
<p>Each BioFiber has <a href="https://doi.org/10.1016/j.conbuildmat.2023.133765">three key components</a>: a tough core fiber made of a polymer called polyvinyl alcohol, a porous layer of hydrogel infused with <em><a href="https://www.sciencedirect.com/topics/immunology-and-microbiology/lysinibacillus-sphaericus">Lysinibacillus sphaericus</a></em> bacteria, and a damage-responsive outer shell. When cracks hit the BioFiber, its outer shell breaks and releases the bacteria into the crack, which starts the self-healing process.</p>
<p>The strong core fibers in BioFiber <a href="https://doi.org/10.1016/j.conbuildmat.2023.133765">bridge the cracks</a> and stop them from growing wider during the healing process.</p>
<p>Surrounding the core fiber, the hydrogel layer is made up of a mesh of polymer chains at the molecular level that attract water. Their spongelike structure can absorb and hold large volumes of water. During the production process, we add calcium to help the hydrogel solidify. </p>
<p>The hydrogel itself is made up of a <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/alginate">natural polymer found in seaweed called alginate</a>, which has special properties that allow it to trap bacteria. Alginate isn’t toxic and is even safe for biomedical applications such as <a href="https://doi.org/10.1155/2020/8886095">drug delivery</a> and <a href="https://doi.org/10.3390/md21030189">tissue engineering</a>.</p>
<p>The hydrogel <a href="https://www.ncbi.nlm.nih.gov/books/NBK556071">houses endospores</a>, which are dormant bacteria. Once the outer shell cracks and the endospores are awakened from their dormant state, they facilitate the self-healing. </p>
<h2>Activating BioFiber</h2>
<p>The endospores need water to activate. Luckily, the middle hydrogel layer absorbs water well. When the concrete cracks, and water from rain, humidity or street runoff seeps in, the spores wake up. </p>
<p>The spores ingest carbon that we specifically add into the concrete mix, as well as calcium in the concrete itself. With these materials, the bacteria facilitates a chemical reaction called microbially induced calcium carbonate precipitation, or MICCP. This reaction creates <a href="https://doi.org/10.1016/j.dibe.2024.100351">calcium carbonate crystals</a>, which build up and fill in the cracks in the concrete.</p>
<p>The crystal shape varies, from sphere to needle-shaped, and each shape is strong enough to heal the cracks. We can alter the type of crystals the bacteria produces by changing the pH level, calcium source and type of bacteria.</p>
<p>Concrete acts like a solid, tough substance because it’s a mix of cement, sand, gravel and water. We toss the BioFibers into the mix and spread them out as the concrete is mixed, ensuring they’re evenly distributed throughout the mixture.</p>
<p>Once the self-healing process ends and the bacteria dies, the activated BioFiber is done – it can’t heal anymore. But since the concrete has many BioFibers distributed throughout, another fiber can mend the next crack. At the moment, we do not know how many cracks BioFiber concrete can heal, and we’re conducing more research to figure that out. </p>
<p>To feed the bacteria, we add the amount of food it needs to stay alive and heal the cracks, depending on how many cracks we anticipate them having to fix. When the bacteria runs out of food, the process stops. The bacteria can live for roughly a couple of weeks during the healing process. </p>
<p>While BioFiber shows initial promise, it does have shortcomings, which could make manufacturing it at a larger scale challenging. The manufacturing process and materials used are specialized and not always affordable and practical. While our first tests suggest that BioFiber extends the life span of concrete, we’ll need more testing, including field trials, to verify those early results.</p>
<p>We hope to eventually commercialize and manufacture the fibers at larger production scales, while in the meantime we continue to run tests and study how to improve BioFiber’s self-healing abilities. We’d like to one day get these fibers into roads and sidewalks to potentially prevent cracking in aging concrete.</p><img src="https://counter.theconversation.com/content/220190/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mohammad Houshmand works for Drexel University. He receives funding from the National Science Foundation.</span></em></p><p class="fine-print"><em><span>Yaghoob Farnam receives funding from the National Science Foundation. In addition to his role as an associate professor at Drexel University, he is co-founder and senior technical advisor for SusMaX Inc. </span></em></p>Your skin heals from cuts and scrapes on its own − what if concrete could do that too?Mohammad Houshmand, Ph.D. Candidate in Civil Engineering, Drexel UniversityYaghoob Farnam, Assistant Professor of Civil Engineering, Drexel UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2141262024-02-20T13:29:38Z2024-02-20T13:29:38Z3D printing promises more efficient ways to make custom explosives and rocket propellants<figure><img src="https://images.theconversation.com/files/575456/original/file-20240213-26-q2ug1p.jpg?ixlib=rb-1.1.0&rect=6%2C3%2C2111%2C1406&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">3D printing can be used to build with all kinds of materials – even those that go 'boom.'</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/printer-printing-prototypes-royalty-free-image/1459229120?phrase=3D+printer&adppopup=true">kynny/iStock via Getty Images</a></span></figcaption></figure><p>Imagine you’re driving to work on a rainy day, when a distracted, reckless driver hits your car out of nowhere. With a “boom,” an air bag deploys faster than you can <a href="https://www.nhtsa.gov/vehicle-safety/air-bags">blink your eyes</a> to save your life. </p>
<p>That air bag deployed rapidly thanks to an energetic material called <a href="https://cen.acs.org/safety/chemicals-make-airbags-inflate-changed/100/i41">sodium azide</a>, which generates nitrogen gas during a chemical reaction to inflate your airbag. But what’s an energetic material? </p>
<p>Energetic materials include <a href="https://www.osti.gov/biblio/1765628">propellants, pyrotechnics, fuels and explosives</a>, and they’re used in all sorts of settings. </p>
<p>Uses of energetic materials include <a href="https://www.explainthatstuff.com/flares.html">flares</a>, <a href="https://www.compoundchem.com/2014/11/20/matches/">matches</a>, <a href="https://www.youtube.com/watch?v=a1Ef1PcPKjk">solid rocket boosters</a>, <a href="https://www.ict.fraunhofer.de/en/comp/em/treib.html">gun propellants</a>, hot <a href="https://www.twi-global.com/technical-knowledge/faqs/what-is-cad-welding">thermite welding</a> used to fuse materials together, <a href="https://theconversation.com/how-do-fireworks-work-a-pyrotechnics-chemist-explains-the-science-behind-the-brilliant-colors-and-sounds-173576">fireworks</a> and the <a href="https://www.gq.com/video/watch/the-breakdown-gq-the-breakdown-explosions">explosive special effects</a> in your favorite action movie. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/575457/original/file-20240213-30-hajfxf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A gold and white rocket, with flames coming out of its end, attached to a concrete scaffold." src="https://images.theconversation.com/files/575457/original/file-20240213-30-hajfxf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/575457/original/file-20240213-30-hajfxf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=750&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575457/original/file-20240213-30-hajfxf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=750&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575457/original/file-20240213-30-hajfxf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=750&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575457/original/file-20240213-30-hajfxf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=943&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575457/original/file-20240213-30-hajfxf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=943&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575457/original/file-20240213-30-hajfxf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=943&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Propellants help rockets blast off.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Rocket_propellant#/media/File:Delta_IV_launch_2013-08-28.jpg">U.S. Air Force/Joe Davila</a></span>
</figcaption>
</figure>
<p>Energetic materials come in many shapes and sizes, but they’re often in a solid form and release a lot of energy through <a href="https://www.nfpa.org/news-blogs-and-articles/blogs/2023/03/27/explosions-vs-deflagrations-vs-detonations">burning or exploding</a>, depending on their shape and the conditions they’re operating in. </p>
<p>I’m a <a href="https://www.technologyreview.com/innovator/monique-mcclain/">mechanical engineering professor</a> who studies <a href="https://scholar.google.com/citations?user=whbrwS0AAAAJ&hl=en">energetic materials</a>. Making energetic materials isn’t easy, but developments in 3D printing could make customization easier, while allowing for more potential scientific applications. </p>
<h2>The role of geometry</h2>
<p>How energetic materials are made affects the shapes that they come in and how they release energy over time. For example, solid rocket propellants are made <a href="https://www.youtube.com/watch?v=E0bnPb1WIuc">similar to a cake</a> where a stand mixer stirs the “batter,” which is mostly made of <a href="https://blogs.nasa.gov/Rocketology/tag/ammonium-perchlorate/">ammonium perchlorate, aluminum and a rubbery binder</a>, before it’s poured into a pan. The “cake” solidifies in the pan while it bakes in the oven. </p>
<p>Typically, rocket propellants have a cylindrical shape, but with a rod in the center. <a href="https://airandspace.si.edu/collection-objects/mandrel-rocket-manufacturing-solid-propellant-rocket-motor/nasm_A20060526000">The rod</a> often has a specific <a href="https://www.nakka-rocketry.net/th_grain.html">cross-sectional shape</a>, like a circle or a star. When the propellant solidifies, the rod is removed, leaving the core shape behind. </p>
<p>The core shape affects how the propellant burns, which can affect the <a href="https://www.youtube.com/watch?v=eVvIZ3f2tSU">thrust of the motor it’s used in</a>. Just by changing the central shape of the propellant, you can make a motor accelerate, slow down or maintain its speed over time. </p>
<p>But this traditional “cake baking” process limits the shapes that you can make. You must be able to remove the rod after the propellant solidifies, so if the rod’s shape is too complex, you might break the propellant, which could make it burn erratically. </p>
<p>Designing propellant shapes that make rockets go faster or fly farther is an active area of research, but engineers need new manufacturing methods to create these increasingly complex designs.</p>
<h2>3D printing to the rescue</h2>
<p><a href="https://www.pcmag.com/news/3d-printing-what-you-need-to-know">3D printing</a> has revolutionized manufacturing in a variety of ways, and researchers like me are trying to understand how it can improve the performance of energetic materials. 3D printing uses a printer to stack up material <a href="https://www.youtube.com/watch?v=Vx0Z6LplaMU">layer by layer</a> to build an object. </p>
<p>3D printing allows you to make custom shapes, print multiple types of material in one part, and save money and material. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Vx0Z6LplaMU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">3D printing can be cost- and time-efficient.</span></figcaption>
</figure>
<p>However, it is very challenging to 3D-print energetic materials for several reasons. Some <a href="https://ntrs.nasa.gov/citations/19720024117">energetic materials are very viscous</a>, which means it is very hard to squeeze that mixture out of a tube with a small nozzle. Imagine squeezing clay out of a small syringe – the material is too thick to easily move through the small hole. </p>
<p>In addition, energetic materials can be dangerous if handled improperly. They can ignite if there is <a href="https://www.osti.gov/servlets/purl/639810">too much heat</a> during the manufacturing process or during storage, or if they are exposed to a <a href="https://apps.dtic.mil/sti/tr/pdf/ADA322856.pdf">static electric shock</a>.</p>
<h2>Recent progress</h2>
<p>Despite this, researchers have made a lot of progress in the <a href="https://doi.org/10.1002/prep.201900060">past decade</a> to overcome some of these challenges. For example, scientists have 3D-printed <a href="https://engineering.purdue.edu/ME/News/inkjetprinted-thermite-combines-energetic-materials-and-additive-manufacturing">reactive inks onto electronics</a> to enable self-destruction if they fall into the wrong hands.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/8QNQRhBstRg?wmode=transparent&start=28" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Scientists are studying how to print thin layers of thermite, a type of energetic material, onto surfaces.</span></figcaption>
</figure>
<p>Theoretically, you could also 3D-print these inks strategically onto old satellites or the <a href="https://www.cnn.com/2022/02/02/world/nasa-international-space-station-retire-iss-scn/index.html">aging International Space Station</a> to break up these orbiting devices into <a href="https://arc.aiaa.org/doi/10.2514/6.2024-2162">small enough debris</a> that burns up in the atmosphere before hitting the ground. </p>
<p>Many researchers are looking into 3D-printing gun propellants. <a href="https://doi.org/10.1002/prep.201900176">Modifying the shape of gun propellants</a> could make bullets that can fly farther. </p>
<p>Others have sought to use 3D printing to reduce the environmental impact of <a href="https://serdp-estcp.mil/projects/details/a04a6382-e4d4-4e7e-b262-2febb6cae014/wp19-1246-project-overview">gun propellants</a> and <a href="https://serdp-estcp.mil/projects/details/7a5dc45b-a30b-485f-93ab-ec3731356b3c/wp19-1300-project-overview">igniters that require harsh solvents</a> to manufacture. These solvents are unsafe, difficult to dispose of and can harm <a href="https://www.epd.gov.hk/epd/english/environmentinhk/air/prob_solutions/vocs_smog.html">the environment</a> and <a href="https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality">peoples’ health</a>. </p>
<p>I showed that it is possible to <a href="https://www.purdue.edu/newsroom/releases/2018/Q2/now-you-can-3d-print-clay,-cookie-dough--or-solid-rocket-fuel.html">3D-print solid rocket propellants</a> that have similar properties to traditionally made propellants. With that research, we now have the opportunity to explore how <a href="https://doi.org/10.2514/1.B38282">propellants made of multiple materials burn</a>, which is new territory. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/OIdLg4zeGso?wmode=transparent&start=2" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">To 3D-print rocket propellants, you first need to figure out how to print very viscous materials.</span></figcaption>
</figure>
<p>For example, instead of using a rod to made a cross-sectional shape in a propellant, you could <a href="https://doi.org/10.2514/1.B38128">3D-print a highly reactive material</a> that you could add to the center. Instead of having to remove that center material, you could burn it up so fast that it leaves a core shape behind. The reactive material would also add energy to the propellant. This would eliminate the need to use and remove a rod to make a central core.</p>
<p>While much of this research is in its infancy, companies such as <a href="https://www.prnewswire.com/news-releases/x-bow-systems-launches-second-successful-bolt-rocket-301851088.html">X-Bow</a> have been 3D-printing propellants and conducting successful flight tests with these motors.</p>
<p>Finally, several researchers have studied how <a href="https://www.machinedesign.com/3d-printing-cad/article/21836373/a-look-inside-the-explosive-3dprinting-industry">3D-printed explosives</a> detonate. When the explosives are printed into a grid-shaped lattice, they react differently when their pores are filled with air or water. This process produces a safer “<a href="https://discover.lanl.gov/news/0317-high-explosives/">switchable” explosive</a> that does not react unless it is in a specific environment. </p>
<p>3D-printing energetic materials is still a new field. Scientists have a long way to go before we completely understand how <a href="https://doi.org/10.1002/prep.202380231">3D printing affects their safety and performance</a>. But every day, scientists like me are finding new ways to use 3D-printed energetics to serve crucial, and sometimes lifesaving, purposes.</p><img src="https://counter.theconversation.com/content/214126/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Monique McClain receives funding from Air Force Office of Scientific Research (AFOSR), Army Research Office (ARO), and National Aeronautics and Space Administration (NASA).</span></em></p>‘Energetic’ materials are ones that readily ignite or detonate. The shapes of those materials have a big effect on how they burn or blow up.Monique McClain, Assistant Professor of Mechanical Engineering, Purdue UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2114702024-01-24T13:29:42Z2024-01-24T13:29:42ZCombining two types of molecular boron nitride could create a hybrid material used in faster, more powerful electronics<figure><img src="https://images.theconversation.com/files/569648/original/file-20240116-15-csiabm.jpg?ixlib=rb-1.1.0&rect=8%2C17%2C5682%2C4471&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hexagonal boron nitride, also known as 'white graphene.'</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/boron-nitride-monolayer-illustration-royalty-free-image/1161024204?phrase=boron+nitride&adppopup=true">Robert Brook/Science Photo Library via Getty Images</a></span></figcaption></figure><p>In chemistry, structure is everything. Compounds with the same chemical formula can have different properties depending on the arrangement of the molecules they’re made of. And compounds with a different chemical formula but a similar molecular arrangement can have similar properties.</p>
<p><a href="https://www.sciencedirect.com/topics/chemistry/graphene">Graphene</a> and a form of boron nitride called hexagonal boron nitride fall into the latter group. Graphene is made up of carbon atoms. Boron nitride, BN, is composed of boron and nitrogen atoms. While their chemical formulas differ, <a href="https://doi.org/10.1063/PT.3.3297">they have a similar structure</a> – so similar that many chemists call hexagonal boron nitride “white graphene.”</p>
<p>Carbon-based graphene has <a href="https://theconversation.com/graphene-is-a-proven-supermaterial-but-manufacturing-the-versatile-form-of-carbon-at-usable-scales-remains-a-challenge-194238">lots of useful properties</a>. It’s thin but strong, and it conducts heat and electricity very well, making it ideal for use in electronics.</p>
<p>Similarly, hexagonal boron nitride has a host of properties similar to graphene that could improve biomedical imaging and drug delivery, as well as computers, smartphones and LEDs. <a href="https://doi.org/10.1038/nmat2711">Researchers have studied</a> this type of boron nitride for many years.</p>
<p>But, hexagonal boron nitride isn’t the only useful form this compound comes in.</p>
<p>As <a href="https://scholar.google.com/citations?user=S5oLGEgAAAAJ&hl=en">materials engineers</a>, <a href="https://ajayan.rice.edu/">our research team</a> has been investigating another type of boron nitride called cubic boron nitride. We want to know if combining the properties of hexagonal boron nitride with cubic boron nitride could open the door to <a href="https://www.azom.com/article.aspx?ArticleID=78">even more useful applications</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569649/original/file-20240116-15-c9h3ox.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Molecular structures of molecules, with atoms represented as blue spheres and bonds represented by gray lines connecting them. The left structure is in the shape of the cube, the right in flat sheets of hexagons." src="https://images.theconversation.com/files/569649/original/file-20240116-15-c9h3ox.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569649/original/file-20240116-15-c9h3ox.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=227&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569649/original/file-20240116-15-c9h3ox.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=227&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569649/original/file-20240116-15-c9h3ox.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=227&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569649/original/file-20240116-15-c9h3ox.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=285&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569649/original/file-20240116-15-c9h3ox.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=285&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569649/original/file-20240116-15-c9h3ox.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=285&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cubic boron nitride, shown on the left, and hexagonal boron nitride, shown on the right.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Structures_cub_hex_BN.gif">Oddball/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>Hexagonal versus cubic</h2>
<p>Hexagonal boron nitride is, as you might guess, boron nitride molecules arranged in the shape of a flat hexagon. It looks honeycomb-shaped, like graphene. Cubic boron nitride has a <a href="https://www.azom.com/article.aspx?ArticleID=78">three-dimensional lattice structure</a> and looks like a diamond at the molecular level.</p>
<p>H-BN is thin, soft and used in cosmetics to give them a silky texture. It doesn’t melt or degrade even under extreme heat, which also makes it useful in electronics and other applications. Some scientists predict it could be used to build a <a href="https://doi.org/10.1016/j.cej.2020.127802">radiation shield</a> for spacecraft.</p>
<p>C-BN is hard and resistant. It’s used in manufacturing to make cutting tools and drills, and it can keep its sharp edge even at high temperatures. It can also help dissipate heat in electronics.</p>
<p>Even though h-BN and c-BN might seem different, when put together, <a href="https://doi.org/10.1021/acs.nanolett.3c01537">our research has found</a> they hold even more potential than either on its own.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566921/original/file-20231220-23-komtmy.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two white powders, the top labeled 'hexagonal boron nitride' and the bottom labeled 'cubic boron nitride' with a circle between them labeled 'mixed phase boron nitride.' The bottom powder is slightly more brown and more clumpy." src="https://images.theconversation.com/files/566921/original/file-20231220-23-komtmy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566921/original/file-20231220-23-komtmy.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=557&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566921/original/file-20231220-23-komtmy.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=557&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566921/original/file-20231220-23-komtmy.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=557&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566921/original/file-20231220-23-komtmy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=700&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566921/original/file-20231220-23-komtmy.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=700&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566921/original/file-20231220-23-komtmy.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=700&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The two forms of boron nitride have some similarities and some differences, but when combined, they can create a substance with a variety of scientific applications.</span>
<span class="attribution"><span class="source">Abhijit Biswas</span></span>
</figcaption>
</figure>
<p>Both types of boron nitride conduct heat and can provide electrical insulation, but one, h-BN, is soft, and the other, c-BN, is hard. So, we wanted to see if they could be used together to create materials with interesting properties.</p>
<p>For example, combining their different behaviors could make a coating material effective for high temperature structural applications. C-BN could provide strong adhesion to a surface, while h-BN’s lubricating properties could resist wear and tear. Both together would keep the material from overheating.</p>
<h2>Making boron nitride</h2>
<p>This class of materials doesn’t occur naturally, so scientists must make it in the lab. In general, high-quality c-BN has been difficult to synthesize, whereas h-BN is relatively easier to make as high-quality films, using what are called vapor phase deposition methods. </p>
<p>In vapor phase deposition, we heat up boron and nitrogen-containing materials until they evaporate. The evaporated molecules then get deposited onto a surface, cool down, bond together and form a thin film of BN.</p>
<p>Our research team has worked on combining h-BN and c-BN using <a href="https://doi.org/10.1021/nl1022139">similar processes</a> to vapor phase deposition, but we can also <a href="https://doi.org/10.1021/acs.nanolett.3c01537">mix powders of the two together</a>. The idea is to build a material with the right mix of h-BN and c-BN for thermal, mechanical and electronic properties that we can fine-tune.</p>
<p>Our team has found the composite substance made from combining both forms of BN together has a variety of potential applications. When you point a laser beam at the substance, it flashes brightly. Researchers could use this property to create display screens and improve radiation therapies in the medical field. </p>
<p>We’ve also found we can tailor how heat-conductive the composite material is. This means engineers could use this BN composite in <a href="https://doi.org/10.1021/acs.nanolett.3c01537">machines that manage heat</a>. The next step is trying to manufacture large plates made of a h-BN and c-BN composite. If done precisely, we can tailor the mechanical, thermal and optical properties to specific applications.</p>
<p>In electronics, h-BN could <a href="https://doi.org/10.1063/PT.3.3297">act as a dielectric – or insulator – alongside graphene</a> in certain, low-power electronics. As a dielectric, h-BN would help electronics operate efficiently and keep their charge. </p>
<p>C-BN could work alongside diamond to create <a href="https://www.nrel.gov/materials-science/wide-bandgap-semiconductors.html">ultrawide band gap materials</a> that allow electronic devices to work at a much higher power. Diamond and c-BN both conduct heat well, and together they could help cool down these <a href="https://doi.org/10.1002/aelm.201600501">high-power devices</a>, which generate lots of extra heat.</p>
<p>H-BN and c-BN separately could lead to electronics that perform exceptionally well in different contexts – together, they have a host of potential applications, as well. </p>
<p>Our BN composite could improve heat spreaders and insulators, and it could work in energy storage machines like supercapacitors, which are <a href="https://www.azonano.com/article.aspx?ArticleID=6643">fast-charging energy storage devices</a>, and rechargeable batteries.</p>
<p>We’ll continue <a href="https://www.preciseceramic.com/blog/boron-nitride-the-superhero-material-of-the-future.html">studying BN’s properties</a>, and how we can use it in lubricants, coatings and wear-resistant surfaces. Developing ways to scale up production will be key for <a href="https://www.linkedin.com/pulse/global-boron-nitride-market-2024-share-future-trends-d1uwf/?published=t">exploring its applications</a>, from materials science to electronics and even environmental science.</p><img src="https://counter.theconversation.com/content/211470/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Pulickel Ajayan receives funding from the Army Research Laboratory and the Army Research Office. </span></em></p><p class="fine-print"><em><span>Abhijit Biswas does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Two forms of the same boron nitride molecules couldn’t look and act more different – but combining them could lead to applications that have the best of both worlds.Pulickel Ajayan, Professor of Materials Science and NanoEngineering, Rice UniversityAbhijit Biswas, Research Scientist in Materials Science and Nanoengineering, Rice UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2162442024-01-16T13:40:18Z2024-01-16T13:40:18ZYour fingerprint is actually 3D − research into holograms could improve forensic fingerprint analysis<figure><img src="https://images.theconversation.com/files/565336/original/file-20231212-25-54j3sc.jpg?ixlib=rb-1.1.0&rect=4%2C17%2C2895%2C2056&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fingerprints have been used as unique identifiers for decades. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/BabeRuthAuction/02eed90749c4440d91a7a4e4ea305c6b/photo?Query=fingerprint&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=949&currentItemNo=18">AP Photo/Patrick Semansky</a></span></figcaption></figure><p>When you use your fingerprint to unlock your smartphone, your phone is looking at a two-dimensional pattern to determine whether it’s the correct fingerprint before it unlocks for you. But the imprint your finger leaves on the surface of the button is actually a 3D structure called a fingermark. </p>
<p>Fingermarks are made up of tiny ridges of oil from your skin. Each ridge is only a few microns tall, or a few hundredths of the thickness of human hair.</p>
<p>Biometric identifiers record fingermarks only as 2D pictures, and although these carry a lot of information, there’s a lot missing. A 2D fingerprint neglects the depth of the fingermark, including pores and scars buried in the ridges of fingers that are difficult to see.</p>
<p>I’m an <a href="https://udayton.edu/directory/engineering/electrical_and_computer/banerjee_partha.php">educator and scientist</a> who studies holography, a field of research that focuses on how to display 3D information. My lab has created a way to map and visualize fingermarks in three dimensions from any perspective on a computer – <a href="https://theconversation.com/five-surprising-ways-holograms-are-revolutionising-the-world-77886">using digital holography</a>.</p>
<h2>Fingermark types</h2>
<p>Scientists categorize fingermarks as either patent, plastic or latent, depending on how visible they are when left on a surface.</p>
<p>Patent fingermarks are the most visible type – bloody fingerprints at crime scenes are one example. Plastic fingermarks are found on soft surfaces, such as clay, Play-Doh or chocolate bars. The human eye can see both <a href="https://doi.org/10.1201/b12882">patent and plastic fingermarks quite easily</a>.</p>
<p>The least visible are latent fingermarks. These are usually found on hard surfaces such as <a href="https://doi.org/10.1201/b12882">glass, metals, woods and plastics</a>. To make them out, a fingerprint examiner has to use physical or chemical methods such as dusting with powder, creating chemical reactions with appropriate reagents or <a href="https://doi.org/10.1186/s41935-017-0009-7">cyanoacrylate fuming</a>. </p>
<p>Cyanoacrylate makes super glue in <a href="https://nij.ojp.gov/library/publications/fingerprint-sourcebook">its liquid form</a>, but as a gas it can make latent fingermarks visible. Researchers develop the prints by letting cyanoacrylate vapor molecules react with components in the latent fingerprint residue.</p>
<p>The geometric details on fingermarks are categorized into three levels. Level 1 encompasses <a href="https://www.forensicsciencesimplified.org/prints/principles.html">visible ridge patterns</a>, so loops, whorls and arches. Level 2 refers to <a href="https://nij.ojp.gov/library/publications/fingerprint-sourcebook">minutiae or small details</a>, such as bifurcations, endings, eyes and hooks. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/565337/original/file-20231212-15-ry9tua.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three fingerprint ridge patterns shown in black and white. The ridges on the left look like a hill, the center looks like a hill with a loop on top, and on the right the ridges form a circle." src="https://images.theconversation.com/files/565337/original/file-20231212-15-ry9tua.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565337/original/file-20231212-15-ry9tua.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=233&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565337/original/file-20231212-15-ry9tua.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=233&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565337/original/file-20231212-15-ry9tua.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=233&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565337/original/file-20231212-15-ry9tua.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=293&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565337/original/file-20231212-15-ry9tua.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=293&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565337/original/file-20231212-15-ry9tua.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=293&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fingerprints have visible ridge structures, such as arches (left), whorls (middle) and loops (right), but at the microscopic level they have much finer patterns and structures.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:%D0%9F%D0%B0%D0%BB%D1%8C%D1%86%D0%B5%D0%B2%D1%8B%D0%B5_%D1%83%D0%B7%D0%BE%D1%80%D1%8B.jpg">ValeriyPolunovskiy/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Finally, Level 3 features, such as pores, scars and creases, are too small for the human eye to resolve. This is where <a href="https://doi.org/10.1117/1.OE.56.3.034117">optical techniques</a> like holography come in handy, since optical wavelengths are in the order of microns, small enough to make out small details on an object.</p>
<h2>Developing fingermark holograms</h2>
<p>Since fingermarks are usually collected as 2D pictures, and holograms display 3D information, my team wanted to develop a technique that can show all the 3D topological characteristics of a fingermark.</p>
<p>To do this, we’ve been collaborating with <a href="https://scholar.google.com/citations?user=wC7o_VAAAAAJ&hl=en">Akhlesh Lakhtakia’s group</a> at Penn State. They developed a specialized technique that deposits a <a href="https://doi.org/10.1117/1.OE.56.3.034117">nanoscale columnar thin film</a> layer, called a CTF, on top of the fingermark to develop and preserve it. </p>
<p>Columnar thin films are dense pillars of <a href="https://doi.org/10.1117/1.OE.56.3.034117">glassy material</a> that uniformly cover the fingermark, like a dense growth of identical trees in a forest. Just as the tops of these trees would reflect the topology of the ground, the tops of these columnar thin films <a href="https://doi.org/10.1016/j.ijleo.2023.171541">replicate the 3D structure</a> of the fingermarks on which they are deposited. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/558698/original/file-20231109-15-x4lbc9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man wearing a blue shirt and green vest, as well as a blue glove, holds a clear petri dish upright, which has three small red squares with fingermarks on them inside." src="https://images.theconversation.com/files/558698/original/file-20231109-15-x4lbc9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558698/original/file-20231109-15-x4lbc9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558698/original/file-20231109-15-x4lbc9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558698/original/file-20231109-15-x4lbc9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558698/original/file-20231109-15-x4lbc9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558698/original/file-20231109-15-x4lbc9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558698/original/file-20231109-15-x4lbc9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Samples collected using CTF film.</span>
<span class="attribution"><span class="source">Banerjee Lab</span></span>
</figcaption>
</figure>
<p><a href="https://science.howstuffworks.com/hologram.htm">To make a hologram</a> of something like a 3D fingermark, researchers split light from a laser into two parts. One part, called the reference wave, shines directly on a digital camera. The other wave shines on the object, in this case the fingermark. </p>
<p>If the object is reflective, the reflected light is also <a href="https://doi.org/10.1117/1.OE.56.3.034117">directed to the digital camera</a> and <a href="https://spie.org/publications/book/2190843?SSO=1">superimposed on the reference wave</a>.</p>
<p>The superposition of waves – both from the reference and the object – creates an interference pattern, which is called a hologram. In digital holography, this hologram, which is a 2D picture, is recorded in the digital camera. Researchers then import the hologram to a computer, where they can use the physical laws of wave propagation to figure out where the light waves from the laser bounced off different parts of the object. </p>
<p>This process allows them <a href="https://spie.org/publications/book/2190843?SSO=1">to reconstruct the object</a> as a 3D picture.</p>
<p>So, the reconstructed hologram has <a href="https://www.biblio.com/book/principles-applied-optics-banerjee-partha-p/d/1473721348">all the 3D details of the object</a>, and you can now visualize the 3D object on a laptop <a href="https://spie.org/publications/book/2190843?SSO=1">from any perspective</a>. </p>
<h2>Picking up fingermarks</h2>
<p>In 2017, our collaboration <a href="https://doi.org/10.1117/1.OE.56.3.034117">reported our first results</a>, where we made 3D pictures of latent fingermarks using the CTF technique. We recorded holograms of the CTF-developed fingermarks with two different wavelengths of light – green and blue – generated from a laser. Using two different wavelengths allowed us to make out tiny details such as pores in the 3D reconstructions. </p>
<p>Lakhtakia’s research group has deposited hundreds of fingermarks on glass, wood and plastic. They’ve then let them age in different environments, at various temperatures and humidity levels, before coating them with CTF film to pick up the fingerprint. My group records the digital holograms of these fingermarks and visualizes them in 3D on a computer. </p>
<p>We have also started working on a better 3D fingermark analysis plan to help identify crime suspects.</p>
<p>The <a href="https://www.mcohio.org/816/Miami-Valley-Regional-Crime-Lab">Miami Valley Regional Crime Lab</a> in Dayton, Ohio, has graded the quality of the fingermarks captured by Lakhtakia’s research group. It will also help us develop a new method for grading the 3D holographic reconstructions, something that does not currently exist. This may involve creating categories to classify how clear the 3D renderings of the fingermarks are.</p>
<p>The use of fingerprints as unique identifiers has a long history, going back to <a href="https://nij.ojp.gov/library/publications/fingerprint-sourcebook">ancient Babylonian and Chinese civilizations</a>. They’ve been used for forensic purposes <a href="https://doi.org/10.1016/j.endeavour.2023.100863">since the late 1890s</a>, starting in Calcutta, India. Our work aims to build on this rich history and use cutting-edge technologies to improve fingermark analysis.</p><img src="https://counter.theconversation.com/content/216244/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Partha Banerjee’s Holography and Metamaterials (HaM) Lab has used Digital Holography for many applications funded by DARPA, Air Force and Army. The current joint work on fingermarks is supported by a grant from the Criminal Investigations and Network Analysis (CINA) Center of the Department of Homeland Security (DHS). </span></em></p>Using fingerprints to catch criminals isn’t 100% accurate, but analyzing fingerprints in 3D, rather than 2D, could improve the process.Partha Banerjee, Professor of Electrical and Computer Engineering, University of DaytonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2146142023-10-24T12:22:02Z2023-10-24T12:22:02ZSpace rocks and asteroid dust are pricey, but these aren’t the most expensive materials used in science<figure><img src="https://images.theconversation.com/files/552576/original/file-20231006-23-aam2il.jpg?ixlib=rb-1.1.0&rect=0%2C34%2C5751%2C3794&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Meteorites can get pricey, but they're not the most expensive material. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/FranceMeteoriteAuction/e075e1b22656489db39610bafb0682af/photo?Query=meteorites&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=341&currentItemNo=5&vs=true">AP Photo/Thibault Camus</a></span></figcaption></figure><p>After a journey of seven years and nearly 4 billion miles, <a href="https://science.nasa.gov/mission/osiris-rex">NASA’s OSIRIS-REx</a> <a href="https://www.space.com/osiris-rex-asteroid-samples-land-houston">spacecraft landed</a> gently in the Utah desert on the morning of Sept. 24, 2023, with a precious payload. <a href="https://science.nasa.gov/mission/osiris-rex">The spacecraft</a> brought back a sample from the asteroid Bennu.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552573/original/file-20231006-27-cm9a07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An artist's illustration of a gray metallic spacecraft hovering above the dark surface of an asteroid, with an arm that reaches down to the surface." src="https://images.theconversation.com/files/552573/original/file-20231006-27-cm9a07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552573/original/file-20231006-27-cm9a07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552573/original/file-20231006-27-cm9a07.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552573/original/file-20231006-27-cm9a07.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552573/original/file-20231006-27-cm9a07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552573/original/file-20231006-27-cm9a07.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552573/original/file-20231006-27-cm9a07.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">OSIRIS-REx collected a sample from the asteroid Bennu.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/20c047ec48f74f6995ffad6b0f54422c?ext=true">NASA/Goddard Space Flight Center via AP</a></span>
</figcaption>
</figure>
<p>Roughly half a pound of material collected from the <a href="https://science.nasa.gov/solar-system/asteroids/101955-bennu/facts/">85 million-ton asteroid</a> (77.6 billion kg) will help scientists learn about the <a href="https://solarsystem.nasa.gov/missions/osiris-rex/in-depth/">formation of the solar system</a>, including whether <a href="https://solarsystem.nasa.gov/asteroids-comets-and-meteors/asteroids/101955-bennu/in-depth/">asteroids like Bennu</a> include the chemical ingredients for life.</p>
<p>NASA’s mission was budgeted at <a href="https://www.asteroidmission.org/qa/">US$800 million</a> and will end up costing around <a href="https://www.planetary.org/space-policy/cost-of-osiris-rex">$1.16 billion</a> for <a href="https://www.nasa.gov/news-release/nasas-first-asteroid-sample-has-landed-now-secure-in-clean-room/">just under 9 ounces of sample</a> (255 g). But is this the most expensive material known? Not even close.</p>
<p>I’m a <a href="https://scholar.google.com/citations?user=OrRLRQ4AAAAJ&hl=en">professor of astronomy</a>. I use Moon and Mars rocks in my teaching and have a modest collection of meteorites. I marvel at the fact that I can hold in my hand something that is billions of years old from billions of miles away.</p>
<h2>The cost of sample return</h2>
<p>A handful of asteroid works out to $132 million <a href="https://www.hoodmwr.com/things-that-weigh-around-1-ounce/">per ounce</a>, or $4.7 million per gram. That’s about 70,000 times the <a href="https://goldprice.org/">price of gold</a>, which has been in the range of $1,800 to $2,000 per ounce ($60 to $70 per gram) for the past few years.</p>
<p>The first extraterrestrial material returned to Earth came from the Apollo program. Between 1969 and 1972, six Apollo missions brought back 842 pounds (382 kg) of <a href="https://curator.jsc.nasa.gov/lunar/">lunar samples</a>.</p>
<p>The <a href="https://www.planetary.org/space-policy/cost-of-apollo">total price tag</a> for the Apollo program, adjusted for inflation, was $257 billion. These Moon rocks were a relative bargain at $19 million per ounce ($674 thousand per gram), and of course Apollo had additional value in demonstrating technologies for human spaceflight. </p>
<p>NASA is planning to bring samples back from Mars in the early 2030s to see if any contain traces of ancient life. The <a href="https://mars.nasa.gov/msr/">Mars Sample Return</a> mission aims to return <a href="https://www.universetoday.com/161264/we-can-only-bring-30-samples-of-mars-back-to-earth-how-do-we-decide/">30 sample tubes</a> with a <a href="https://downloads.regulations.gov/NASA-2022-0002-0002/attachment_5.pdf">total weight of a pound</a> (450 g). The <a href="https://science.nasa.gov/mission/mars-2020-perseverance">Perseverance rover</a> has already <a href="https://www.universetoday.com/160109/perseverance-is-building-up-a-big-collection-of-mars-samples/">cached 10 of these samples</a>. </p>
<p>However, <a href="https://www.science.org/content/article/mars-sample-return-got-new-price-tag-it-s-big">costs have grown</a> because the mission is complex, involving multiple robots and spacecraft. Bringing back the samples could run $11 billion, putting their cost at $690 million per ounce ($24 million per gram), five times the unit cost of the Bennu samples.</p>
<h2>Some space rocks are free</h2>
<p>Some space rocks cost nothing. Almost 50 tons of free samples from the solar system <a href="https://science.nasa.gov/solar-system/meteors-meteorites/">rain down on the Earth</a> every day. Most burn up in the atmosphere, but if they reach the ground <a href="https://www.amnh.org/explore/news-blogs/on-exhibit-posts/meteor-meteorite-asteroid">they’re called meteorites</a>, and most of those come from asteroids. </p>
<p><a href="https://www.nhm.ac.uk/discover/types-of-meteorites.html">Meteorites can get costly</a> because it can be difficult to recognize and retrieve them. Rocks all look similar unless you’re a geology expert. </p>
<p>Most meteorites are stony, <a href="https://www.britannica.com/science/chondrite">called chondrites</a>, and they can be bought online for as little as $15 per ounce (50 cents per gram). Chondrites differ from normal rocks in containing <a href="https://www.amnh.org/exhibitions/permanent/meteorites/origins-of-the-solar-system/chondrules">round grains called chondrules</a> that formed as molten droplets in space at the birth of the solar system 4.5 billion years ago.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/552568/original/file-20231006-19-kgbnz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A meteorite that looks like a long gray rock with dark gray veins running across it." src="https://images.theconversation.com/files/552568/original/file-20231006-19-kgbnz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/552568/original/file-20231006-19-kgbnz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=305&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552568/original/file-20231006-19-kgbnz8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=305&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552568/original/file-20231006-19-kgbnz8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=305&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552568/original/file-20231006-19-kgbnz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=384&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552568/original/file-20231006-19-kgbnz8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=384&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552568/original/file-20231006-19-kgbnz8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=384&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A chondrite from the Viñales meteorite, which originated from the asteroid belt between Mars and Jupiter.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Ordinary_chondrite_%28Vi%C3%B1ales_Meteorite%29_15.jpg">Ser Amantio di Nicolao/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p><a href="https://aerolite.org/shop/iron-meteorites/">Iron meteorites</a> are distinguished by a dark crust, caused by melting of the surface as they come through the atmosphere, and an internal pattern of long metallic crystals. They cost $50 per ounce ($1.77 per gram) or even higher. <a href="https://geology.com/meteorites/value-of-meteorites.shtml">Pallasites</a> are stony-iron meteorites laced with the mineral olivine. When cut and polished, they have a translucent yellow-green color and can cost over $1,000 per ounce ($35 per gram).</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/552571/original/file-20231006-21-vjnv0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A brown-gray meteorite that's roughly circular with textured ridges" src="https://images.theconversation.com/files/552571/original/file-20231006-21-vjnv0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/552571/original/file-20231006-21-vjnv0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552571/original/file-20231006-21-vjnv0r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552571/original/file-20231006-21-vjnv0r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552571/original/file-20231006-21-vjnv0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552571/original/file-20231006-21-vjnv0r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552571/original/file-20231006-21-vjnv0r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An iron meteorite.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Odessa_%28iron%29_meteorite.jpg">Llez/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>More than a few meteorites have reached us from the Moon and Mars. Close to 600 have been recognized as <a href="https://sites.wustl.edu/meteoritesite/items/lunar-meteorites/">coming from the Moon</a>, and <a href="https://www.catawiki.com/en/stories/4683-10-most-expensive-meteorites-ever-offered-up-on-earth">the largest</a>, weighing 4 pounds (1.8 kg), sold for a price that works out to be about $4,700 per ounce ($166 per gram). </p>
<p>About 175 meteorites are identified as <a href="https://www2.jpl.nasa.gov/snc/">having come from Mars</a>. <a href="https://aerolite.org/shop/mars-meteorites/">Buying one</a> would cost about $11,000 per ounce ($388 per gram). </p>
<p>Researchers can figure out <a href="https://science.nasa.gov/solar-system/meteors-meteorites/facts/">where meteorites come from</a> by using their landing trajectories to project their paths back to the asteroid belt or comparing their composition with different classes of asteroids. Experts can tell where Moon and Mars rocks come from by their geology and mineralogy.</p>
<p>The limitation of these “free” samples is that there is no way to know where on the Moon or Mars they came from, which limits their scientific usefulness. Also, they start to get contaminated as soon as they land on Earth, so it’s hard to tell if any microbes within them are extraterrestrial.</p>
<h2>Expensive elements and minerals</h2>
<p>Some elements and minerals are expensive because they’re scarce. Simple <a href="http://www.leonland.de/elements_by_price/en/list">elements in the periodic table</a> have low prices. Per ounce, carbon costs one-third of a cent, iron costs 1 cent, aluminum costs 56 cents, and even mercury is less than a dollar (per 100 grams, carbon costs $2.40, iron costs less than a cent and alumnium costs 19 cents). Silver is $14 per ounce (50 cents per gram), and gold, $1,900 per ounce ($67 per gram). </p>
<p><a href="https://alansfactoryoutlet.com/how-much-do-elements-cost-the-price-of-75-elements-per-kilogram/">Seven radioactive elements</a> are extremely rare in nature and so difficult to create in the lab that they eclipse the price of NASA’s Mars Sample Return. Polonium-209, the most expensive of these, costs $1.4 trillion per ounce ($49 billion per gram).</p>
<p>Gemstones can be expensive, too. <a href="https://www.gemsociety.org/article/emerald-jewelry-and-gemstone-information/">High-quality emeralds</a> are 10 times the <a href="https://goldprice.org/">price of gold</a>, and <a href="https://ajediam.com/diamond-prices/white-natural-diamond/">white diamonds</a> are 100 times the price of gold. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/554101/original/file-20231016-15-63z3ek.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A circular white diamond sitting on a white surface." src="https://images.theconversation.com/files/554101/original/file-20231016-15-63z3ek.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/554101/original/file-20231016-15-63z3ek.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=727&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554101/original/file-20231016-15-63z3ek.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=727&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554101/original/file-20231016-15-63z3ek.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=727&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554101/original/file-20231016-15-63z3ek.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=914&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554101/original/file-20231016-15-63z3ek.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=914&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554101/original/file-20231016-15-63z3ek.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=914&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">High-quality white diamonds can cost millions of dollars.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/eeaab33d812a487ebfd2e5a76a25eb03?ext=true">AP Photo/Mary Altaffer</a></span>
</figcaption>
</figure>
<p>Some diamonds have a boron impurity that gives them a <a href="https://www.diamonds.pro/education/blue/">vivid blue hue</a>. They’re found in only a handful of mines worldwide, and at <a href="https://www.usatoday.com/story/money/2022/04/28/worlds-largest-blue-diamond-sells/9567999002/">$550 million per ounce</a> ($19 million per gram) they rival the cost of the upcoming Mars samples – an ounce is 142 carats, but very few gems are that large. </p>
<p>The <a href="https://www.sciencealert.com/scientists-create-world-s-most-expensive-material-valued-at-145-million-per-gram">most expensive synthetic material</a> is a tiny spherical “cage” of carbon with a nitrogen atom trapped inside. The atom inside the cage is extremely stable, so can be used for timekeeping. <a href="https://arstechnica.com/science/2015/12/oxford-company-now-selling-endohedral-fullerenes-priced-at-110-million-per-gram/">Endohedral fullerenes</a> are made of carbon material that may be used to create extremely accurate atomic clocks. They can cost $4 billion per ounce ($141 million per gram).</p>
<h2>Most expensive of all</h2>
<p><a href="https://www.livescience.com/32387-what-is-antimatter.html">Antimatter</a> occurs in nature, but it’s exceptionally rare because any time an antiparticle is created it quickly annihilates with a particle and produces radiation. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/7MkfMGzMcf8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">At CERN’s ‘antimatter factory,’ scientists create antimatter in very small quantities.</span></figcaption>
</figure>
<p>The <a href="https://royalsocietypublishing.org/doi/10.1098/rsta.2010.0026">particle accelerator at CERN</a> can produces 10 million antiprotons per minute. That sounds like a lot, but <a href="https://archive.ph/6RUrA">at that rate</a> it would take billions of years and cost a billion billion (10<sup>18</sup>) dollars to generate an ounce (3.5 x 10<sup>16</sup> dollars per gram). </p>
<p><a href="https://www.newscientist.com/article/mg24232342-600-how-star-treks-warp-drives-touch-on-one-of-physics-biggest-mysteries/">Warp drives</a> as envisaged by “Star Trek,” which are powered by matter-antimatter annihilation, will have to wait.</p><img src="https://counter.theconversation.com/content/214614/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Impey receives funding from the National Science Foundation. </span></em></p>Some space rocks you can get for free – if you know how to identify them. Rarer materials cost more, and the asteroid sample NASA just brought back has a high price tag.Chris Impey, University Distinguished Professor of Astronomy, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1928002022-10-19T18:37:54Z2022-10-19T18:37:54ZA new type of material called a mechanical neural network can learn and change its physical properties to create adaptable, strong structures<figure><img src="https://images.theconversation.com/files/490679/original/file-20221019-12170-qt1idp.JPG?ixlib=rb-1.1.0&rect=48%2C78%2C3977%2C2939&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This connection of springs is a new type of material that can change shape and learn new properties.</span> <span class="attribution"><span class="source">Jonathan Hopkins</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p><em>The <a href="https://theconversation.com/us/topics/research-brief-83231">Research Brief</a> is a short take about interesting academic work.</em></p>
<h2>The big idea</h2>
<p>A new type of material can learn and improve its ability to deal with unexpected forces thanks to a unique lattice structure with connections of variable stiffness, as <a href="https://doi.org/10.1126/scirobotics.abq7278">described in a new paper</a> by my colleagues and me. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/490682/original/file-20221019-23-rnqscu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A hand holding a small, complex cube of plastic." src="https://images.theconversation.com/files/490682/original/file-20221019-23-rnqscu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/490682/original/file-20221019-23-rnqscu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490682/original/file-20221019-23-rnqscu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490682/original/file-20221019-23-rnqscu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490682/original/file-20221019-23-rnqscu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490682/original/file-20221019-23-rnqscu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490682/original/file-20221019-23-rnqscu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Architected materials – like this 3D lattice – get their properties not from what they are made out of, but from their structure.</span>
<span class="attribution"><span class="source">Ryan Lee</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The new material is a type of architected material, which gets its properties mainly from the geometry and specific traits of its design rather than what it is made out of. Take hook-and-loop fabric closures like Velcro, for example. It doesn’t matter whether it is made from cotton, plastic or any other substance. As long as one side is a fabric with stiff hooks and the other side has fluffy loops, the material will have the sticky properties of Velcro.</p>
<p>My colleagues and I based our new material’s architecture on that of an artificial neural network – layers of interconnected nodes that can <a href="https://doi.org/10.1109/ACCESS.2019.2945545">learn to do tasks</a> by changing how much importance, or weight, they place on each connection. We hypothesized that a mechanical lattice with physical nodes could be trained to take on certain mechanical properties by adjusting each connection’s rigidity. </p>
<p>To find out if a mechanical lattice would be able to adopt and maintain new properties – like taking on a new shape or changing directional strength – we started off by building a computer model. We then selected a desired shape for the material as well as input forces and had a computer algorithm tune the tensions of the connections so that the input forces would produce the desired shape. We did this training on 200 different lattice structures and found that a triangular lattice was best at achieving all of the shapes we tested. </p>
<p>Once the many connections are tuned to achieve a set of tasks, the material will continue to react in the desired way. The training is – in a sense – remembered in the structure of the material itself.</p>
<p>We then built a physical prototype lattice with adjustable electromechanical springs arranged in a triangular lattice. The prototype is made of 6-inch connections and is about 2 feet long by 1½ feet wide. And it worked. When the lattice and algorithm worked together, the material was able to learn and change shape in particular ways when subjected to different forces. We call this new material a mechanical neural network.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/490683/original/file-20221019-14-emmwwr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of hydraulic springs arranged in a triangular lattice" src="https://images.theconversation.com/files/490683/original/file-20221019-14-emmwwr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/490683/original/file-20221019-14-emmwwr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490683/original/file-20221019-14-emmwwr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490683/original/file-20221019-14-emmwwr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490683/original/file-20221019-14-emmwwr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490683/original/file-20221019-14-emmwwr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490683/original/file-20221019-14-emmwwr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The prototype is 2D, but a 3D version of this material could have many uses.</span>
<span class="attribution"><span class="source">Jonathan Hopkins</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Why it matters</h2>
<p>Besides some <a href="https://doi.org/10.1007/BF00436764">living tissues</a>, very few materials can learn to be better at dealing with unanticipated loads. Imagine a plane wing that suddenly catches a gust of wind and is forced in an unanticipated direction. The wing can’t change its design to be stronger in that direction.</p>
<p>The prototype lattice material we designed can adapt to changing or unknown conditions. In a wing, for example, these changes could be the accumulation of internal damage, changes in how the wing is attached to a craft or fluctuating external loads. Every time a wing made out of a mechanical neural network experienced one of these scenarios, it could strengthen and soften its connections to maintain desired attributes like directional strength. Over time, through successive adjustments made by the algorithm, the wing adopts and maintains new properties, adding each behavior to the rest as a sort of muscle memory.</p>
<p>This type of material could have far reaching applications for the longevity and efficiency of built structures. Not only could a wing made of a mechanical neural network material be stronger, it could also be trained to morph into shapes that maximize fuel efficiency in response to changing conditions around it.</p>
<h2>What’s still not known</h2>
<p>So far, our team has worked only with 2D lattices. But using computer modeling, we predict that 3D lattices would have a much larger capacity for learning and adaptation. This increase is due to the fact that a 3D structure could have tens of times more connections, or springs, that don’t intersect with one another. However, the mechanisms we used in our first model are far too complex to support in a large 3D structure. </p>
<h2>What’s next</h2>
<p>The material my colleagues and I created is a proof of concept and shows the potential of mechanical neural networks. But to bring this idea into the real world will require figuring out how to make the individual pieces smaller and with precise properties of flex and tension.</p>
<p>We hope new research in the <a href="https://doi.org/10.1039/C8MH01100A">manufacturing of materials at the micron scale</a>, as well as work on <a href="https://doi.org/10.1016/j.eml.2020.101120">new materials with adjustable stiffness</a>, will lead to advances that make powerful smart mechanical neural networks with micron-scale elements and dense 3D connections a ubiquitous reality in the near future.</p><img src="https://counter.theconversation.com/content/192800/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan Lee has received funding from the Air Force Office of Science Research . </span></em></p>Computer-based neural networks can learn to do tasks. A new type of material, called a mechanical neural network, applies similar ideas to a physical structure.Ryan H. Lee, PhD Student in Mechanical and Aerospace Engineering, University of California, Los AngelesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1911122022-10-05T13:49:37Z2022-10-05T13:49:37ZConstruction waste is costly: what’s causing it on South African building sites<figure><img src="https://images.theconversation.com/files/486073/original/file-20220922-15568-2f1xe7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">PeopleImages/Getty Images</span></span></figcaption></figure><p>The construction industry contributes significantly to a country’s economy through infrastructure development. The industry has <a href="https://resources.oxfordeconomics.com/hubfs/Future%20of%20Construction_Full%20Report_FINAL.pdf">expanded</a> rapidly worldwide and further <a href="https://www.statista.com/statistics/1290105/global-construction-market-size-with-forecasts/">growth</a> is expected.</p>
<p>This has contributed to a great deal more <a href="https://ieeexplore.ieee.org/document/6504333">construction waste being generated</a> – which has been identified as one of the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0959652617330512">core problems</a> in the construction industry across the world. The literature suggests that as much as <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/construction-waste">30%</a> of the material delivered to a construction site ends up as waste.</p>
<p>The increase in waste has been driven by the fact that construction projects are now much more complex. This has made it harder for construction managers to manage waste effectively.</p>
<p>Also, building waste is <a href="https://ascelibrary.org/doi/10.1061/%28ASCE%290733-9364%282002%29128%3A4%28316%29">difficult to recycle and reuse</a>. A lot is contaminated – for example when wet concrete or mortar is dumped on other waste materials.</p>
<p>In South Africa between <a href="http://www.ieomsociety.org/ieom2020/papers/669.pdf">5 million and 8 million tonnes</a> of construction waste are generated annually. Only a small fraction is reused or recycled. The result is that a large amount of waste is <a href="https://ieeexplore.ieee.org/document/6504333">disposed of in landfills</a>, which are rapidly reaching capacity in many places. </p>
<p>One way to approach the problem is through the principle of “lean engineering” – a strong focus on minimising waste. To find out whether these principles were being used on construction sites in South Africa, we did <a href="https://www.tandfonline.com/doi/full/10.1080/0035919X.2022.2045383">research</a> in Gauteng province. The province is the economic hub of the country and region and has the greatest number of construction projects.</p>
<p>We found these principles were not being used widely. But all the construction managers in our study were aware of them and their potential value. This suggests there is scope for improvement in waste management.</p>
<p>Our key finding was that training site workers could make a big difference to waste control and prevention. This is aligned with lean thinking in that it aims to empower people to play a part. </p>
<h2>What happens on building sites</h2>
<p>For our study, we interviewed ten construction managers sampled randomly from the <a href="https://www.cidb.org.za/">Construction Industry Development Board</a> list of registered contractors. We limited the selection to medium-sized companies. </p>
<p>Eight themes emerged from the interviews: types of material waste; causes of physical waste; methods to minimise waste; benefits; cost and time implications; application of lean construction; waste management plan; and most effective method to minimise waste. </p>
<p>We found that <a href="https://www.civilejournal.org/index.php/cej/article/view/1085">procurement during construction</a> played a role in the waste generated. Sometimes wrong items were ordered, or there was over-stocking caused by not being able to purchase small quantities, or the wrong materials were delivered.</p>
<p>Frequent variation orders, waiting for replacements, materials that were not in compliance and inaccurate estimation methods also contributed to <a href="https://www.tandfonline.com/doi/full/10.1080/17452007.2011.594576">construction waste</a>.</p>
<p>Concrete and other cementitious materials were most frequently cited, followed by bricks. Plastic and cement bags, formwork and sand were also mentioned. </p>
<p>Participants explained that concrete waste happened when it was poured to an incorrect level, requiring demolition and rework. Ordering more ready-mix concrete also caused waste. </p>
<p>Brick waste on the building sites happened when bricklayers broke the brick in half and did not use the remaining half. </p>
<p>The two most prevalent reasons that were cited for the causes of waste were lack of skill of labourers and subcontractors, and poor supervision. Other reasons included poor material handling, negligence, speed of execution, design changes, poor management and planning, and the normal work process. </p>
<p>Construction workers sometimes did incorrect work, leaving waste after the incorrect work was demolished. </p>
<h2>Pinpointing solutions</h2>
<p>The respondents identified a range of methods for reducing waste. The most prevalent was reuse and recycling, particularly concrete, mortar and bricks, which can be used for <a href="https://www.sciencedirect.com/science/article/abs/pii/S0921344907002248">rubble fill</a>. Many of the sites promoted sorting and recycling by hiring skips from specialist companies.</p>
<p>Other methods included proper material handling, reducing offcuts and proper quantification. Respondents mentioned management methods like weekly <a href="https://safetyculture.com/topics/toolbox-topics/">“toolbox” meetings</a>, issuing of non-conformance notices and raising awareness of the cost implications of waste. </p>
<p>Respondents mostly concurred on the benefits of waste reduction. Cost saving and improved profitability were mentioned six times. Six of the respondents highlighted reduction in pollution and a cleaner site. </p>
<p>All ten agreed that construction waste had a negative effect on project duration and profitability because <a href="https://researchspace.csir.co.za/dspace/handle/10204/7576">waste took up space on the construction site</a>. Removing it resulted in delays. Additional costs were incurred through extra supervision, cleaning, skip hire and transportation, as well as penalties for delayed completion. </p>
<p>Only two of the sites were contractually required to have a waste management plan, which included the use of skips, prevention of soil contamination, disposal at a registered dumping site and the recruitment of a specialist waste removal subcontractor. Some respondents reported that they used waste management plans created by the construction company. Others did not see the need for a plan as this was not specifically required in any national or municipal legislation or regulations. </p>
<p>Seven of the respondents used lean construction tools. Several countries – such as US, UK and China – have achieved significant advantages by following lean construction principles. But the <a href="https://www.researchgate.net/publication/340977788_The_Construction_Industry_in_the_Fourth_Industrial_Revolution">approach</a> in South Africa seems underutilised because of technical and cultural constraints. </p>
<p>The remaining three respondents indicated that their companies were planning to start using lean construction tools.</p>
<h2>What next</h2>
<p>There appears to be widespread awareness of lean construction and its advantages in minimising waste in Gauteng. But there’s still room for more companies to use the approach and to explore a broader range of tools. </p>
<p>The greatest challenges to implementation lie in poor supervisory capacity, low levels of skills in the labour force, cultural diversity in establishing levels of quality, late issue of information and shortages of materials.</p>
<p>One of our recommendations is that training and education of site workers could make a major contribution to waste control and prevention.</p>
<p>Gauteng’s landfill sites are rapidly reaching capacity and there is a scarcity of potential sites for new landfills. The construction industry should therefore take a more environmentally responsible approach, as a major contributor of waste. </p>
<p><em>Phuluphedziso Rambuwani contributed to this article</em></p><img src="https://counter.theconversation.com/content/191112/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anne Fitchett does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The complexity of construction projects has driven an increase in building waste, which is difficult to recycle and reuse. But there are ways to minimise the problem.Anne Fitchett, Associate Professor and Assistant Dean, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1890802022-08-24T15:35:57Z2022-08-24T15:35:57ZOur atom-moving laser sculpts matter into weird new shapes – new research<figure><img src="https://images.theconversation.com/files/480773/original/file-20220824-24-sdo0s6.jpg?ixlib=rb-1.1.0&rect=0%2C240%2C1024%2C525&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">MENALABA/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Getting atoms to do what you want isn’t easy – but it’s at the heart of a lot of groundbreaking research in physics. </p>
<p>Creating and controlling the behaviour of new forms of matter is of particular interest, and an active area of research. Our new study, <a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.073902">published in Physical Review Letters</a>, has uncovered a brand new way of sculpting ultra-cold atoms into different shapes using laser light.</p>
<p>Ultracold atoms, cooled to temperatures close to absolute zero (-273°C), are of great interest to researchers as they allow them to see and explore physical phenomena that would otherwise be impossible. At these temperatures, cooler than outer space, groups of atoms form a new state of matter (not solid, liquid or gas) known as <a href="https://www.livescience.com/54667-bose-einstein-condensate.html">Bose–Einstein condensates</a> (BEC). In 2001, physicists were <a href="https://www.nobelprize.org/prizes/physics/2001/summary/">awarded the Nobel prize</a> for generating such a condensate.</p>
<p>The defining feature of a BEC is that its atoms behave very differently to what we normally expect. Instead of acting as independent particles, they all have the same (very low) energy and are coordinated with each other. </p>
<p>This is similar to the difference between photons (light particles) coming from the Sun, which may have many different wavelengths (energies) and oscillate independently, and those in laser beams, which all have the same wavelength and oscillate together.</p>
<p>In this new state of matter, the atoms act much more like a single, wave-like structure than a group of individual particles. Researchers have been able to demonstrate wave-like interference patterns between two different BECs and even produce moving “BEC droplets”. The latter can be thought of as <a href="https://www.rle.mit.edu/cua_pub/ketterle_group/Projects_1996/Pubs_96/kett96_Physica_Sc.pdf">the atomic equivalent of a laser beam</a>.</p>
<h2>Moving droplets</h2>
<p>In our latest study, performed with our colleagues <a href="https://www.strath.ac.uk/staff/robbgordondr/">Gordon Robb</a> and <a href="https://www.strath.ac.uk/staff/oppogian-lucaprof/">Gian-Luca Oppo</a>, we investigated how specially shaped laser beams can be used to manipulate ultracold atoms of a BEC. The idea of using light to move objects is not new: when light falls on an object it can exert a (very small) force. This radiation pressure is the principle behind <a href="https://theconversation.com/how-to-sail-through-space-on-sunbeams-solar-satellite-leads-the-way-42223">the idea of solar sails</a>, where the force exerted by sunlight on large mirrors can be used to propel a spacecraft through space.</p>
<p>In this study, however, we used a particular type of light that is capable of not just “pushing” the atoms, but also rotating them around, a bit like an “<a href="https://doi.org/10.1103/PhysRevLett.75.826">optical spanner</a>”. These laser beams look like bright rings (or doughnuts) rather than spots and they have a twisted (helical) wavefront, as shown in the image below.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/480358/original/file-20220822-64444-k3nggh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480358/original/file-20220822-64444-k3nggh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=169&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480358/original/file-20220822-64444-k3nggh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=169&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480358/original/file-20220822-64444-k3nggh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=169&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480358/original/file-20220822-64444-k3nggh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=213&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480358/original/file-20220822-64444-k3nggh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=213&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480358/original/file-20220822-64444-k3nggh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=213&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Light carrying orbital angular momentum (OAM, m) ‘twists’ as it moves.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Under the correct conditions, when such twisted light is shone on to a moving BEC the atoms in it are first attracted towards the bright ring before being rotated around it. As the atoms rotate, both light and atoms start to form droplets which orbit the original direction of the laser beam before being ejected outwards, away from the ring. </p>
<p>The number of droplets is equal to twice the number of light twists. By changing the number, or direction, of the twists in the initial laser beam, we had full control over the number of droplets that formed, and the speed and direction of their subsequent rotation (see the image below). We could even prevent the atomic droplets from escaping from the ring so that they continued to orbit for much longer, producing a form of ultracold atomic current. </p>
<figure class="align-center ">
<img alt="A graphic demonstrating how twisted light shines on to a moving BEC," src="https://images.theconversation.com/files/480333/original/file-20220822-65738-91dtn2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480333/original/file-20220822-65738-91dtn2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=341&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480333/original/file-20220822-65738-91dtn2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=341&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480333/original/file-20220822-65738-91dtn2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=341&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480333/original/file-20220822-65738-91dtn2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=429&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480333/original/file-20220822-65738-91dtn2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=429&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480333/original/file-20220822-65738-91dtn2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=429&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Twisted light shines on to a moving BEC, sculpting it into a ring before breaking it into a number of BEC droplets that orbit the direction of the light before breaking free and twisting away.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Ultracold atomic currents</h2>
<p>This approach of shining twisted light through ultracold atoms opens a new and simple way of controlling and sculpting matter into further unconventional and complex shapes. </p>
<p>One of the most exciting potential applications of BECs is the generation of “<a href="https://ui.adsabs.harvard.edu/abs/2021arXiv210708561A/abstract">atomtronic circuits</a>”, where matter waves of ultracold atoms are guided and manipulated by optical and/or magnetic fields to form advanced equivalents of electronic circuits and devices such as transistors and diodes. Being able to reliably manipulate a BEC’s shape will ultimately help create atomtronic circuits. </p>
<p>Our ultracold atoms, acting here like an “<a href="https://www.sciencedaily.com/releases/2020/09/200908093746.htm">atomtronic superconducting quantum interference device</a>”, have the potential to provide far superior devices than conventional electronics. That’s because neutral atoms result in less information loss than electrons which normally make up current. We also have the ability to change features of the device more easily.</p>
<p>Most excitingly, however, is the fact that our method allows us the possibility to produce complex atomtronic circuits that would simply be impossible to design with normal materials. This could help design highly controllable and easily reconfigurable quantum sensors capable of measuring tiny magnetic fields that would otherwise be immeasurable. Such sensors <a href="https://www.sciencedaily.com/releases/2020/09/200908093746.htm">would be useful</a> in areas ranging from basic physics research to discovering new materials or measuring signals from the brain.</p><img src="https://counter.theconversation.com/content/189080/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Grant Henderson receives funding from from Engineering and Physical Sciences Research Council (EP/R513349/1) via a Doctoral Training Partnership and from the European Training Network ColOpt, which is funded by the European Union (EU) Horizon 2020 program under the Marie Skłodowska-Curie Action, Grant Agreement No. 721465.</span></em></p><p class="fine-print"><em><span>Alison Yao receives funding from Engineering and Physical Sciences Research Council (EP/R513349/1) via a Doctoral
Training Partnership and from the European Training Network ColOpt, which is funded by the European Union (EU) Horizon 2020 program under the Marie Skłodowska-Curie Action, Grant Agreement No. 721465. </span></em></p>Twisted laser light may help launch a revolution in technology.Grant Henderson, PhD candidate in Physics, University of Strathclyde Alison Yao, Senior Lecturer of Physics, University of Strathclyde Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1796852022-03-21T15:18:05Z2022-03-21T15:18:05ZThe inspiring architect from Burkina Faso who lifted world’s biggest prize<figure><img src="https://images.theconversation.com/files/453306/original/file-20220321-13-5p72ex.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Burkinabe architect Diébédo Francis Kéré.</span> <span class="attribution"><span class="source">Photo by ODD ANDERSEN/AFP via Getty Images</span></span></figcaption></figure><p><em><a href="https://www.kerearchitecture.com/">Diébédo Francis Kéré</a> has become <a href="https://www.pritzkerprize.com/laureates">the first African</a> and the first black person to be <a href="https://www.theguardian.com/artanddesign/2022/mar/15/it-is-unbelievable-francis-kere-becomes-first-black-architect-to-win-the-pritzker-prize">awarded</a> architecture’s highest international honour, the 2022 <a href="https://www.pritzkerprize.com/">Pritzker Architecture Prize</a>. Kéré was born in Burkina Faso, West Africa, and built his <a href="https://www.kerearchitecture.com/work">architectural practice</a> designing schools and medical facilities that were most often built by local communities with minimal resources and a very careful selection of affordable and sustainable materials. It was this approach that led to his architecture <a href="https://www.kerearchitecture.com">firm</a> receiving global recognition. We asked architect and African architecture researcher Paulo Moreia to tell us more about Kéré and his win.</em></p>
<hr>
<h2>An introduction to Francis Kéré</h2>
<p><a href="https://www.kerearchitecture.com/about-us">Francis Kéré</a> is a 56-year-old internationally renowned architect. He was born in Gando, a small village in Burkina Faso. He turned his destiny around through education, becoming one of the most representative figures in the African diaspora. </p>
<p>As a child, Francis had to leave his family to attend school in the nearest town. Driven by his own optimism, and by the awareness that in his home country only education could make a difference, Kéré moved to Berlin on a carpentry scholarship and to study architecture. Even before he finished his studies, he designed a primary school in Gando. </p>
<p>In Germany he founded an association to raise funds to build the school, translated as ‘Bricks for Gando’, it was later renamed the <a href="https://www.kerefoundation.com/">Kéré Foundation</a>.</p>
<h2>What kind of architecture is he known for?</h2>
<p>The <a href="https://www.archdaily.com/785955/primary-school-in-gando-kere-architecture">Gando school</a> is a model of sustainable building. Its features include allowing cooling air to pass through and around the building. Another is its innovative use of widely available local resources – both materials and unskilled labour.</p>
<p>It has become an example of the power of architecture to uplift and inspire.</p>
<p>The <a href="https://www.dezeen.com/2017/10/17/movie-diebedo-francis-kere-gando-school-burkina-faso-interview-video/">first school</a> built using this model – in Gando in 2001 – encouraged the implementation of further projects: another school, then a library. These buildings, in turn, have attracted other buildings around them – and even the neighbouring villages have built their own schools following Gando’s cooperative approach. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/453308/original/file-20220321-23-1nrmukz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453308/original/file-20220321-23-1nrmukz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453308/original/file-20220321-23-1nrmukz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453308/original/file-20220321-23-1nrmukz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453308/original/file-20220321-23-1nrmukz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453308/original/file-20220321-23-1nrmukz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453308/original/file-20220321-23-1nrmukz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Village-Opera school designed by Kéré, in Laongo in Gabon.</span>
<span class="attribution"><span class="source">OLYMPIA DE MAISMONT/AFP via Getty Images</span></span>
</figcaption>
</figure>
<p>When architecture has such an impact in the context where it operates, it can only be described as a powerful type of architecture. The impact extended to the whole nation. Less than 15 years after building his first school, Kéré was invited to design Burkina Faso’s <a href="https://www.dezeen.com/2017/07/03/movie-burkina-faso-parliament-building-national-assembly-diebedo-francis-kere-video-interview/">national parliament</a>. It also extended beyond the country’s borders – across the continent and then further afield. In Africa there have been projects in Benin, Kenya, Mali and Mozambique. Worldwide there have been projects in Europe, America and Asia. Kéré’s school inspired <a href="http://paulomoreira.net/projects/kapalanga-school/">my own work</a> as an architect in Angola.</p>
<h2>What is the Pritzker Prize?</h2>
<p>It is architecture’s highest honour. It’s granted each year to architects whose work has achieved excellence. This year it is in its <a href="https://www.pritzkerprize.com/">45th edition</a>.</p>
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<p>
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Read more:
<a href="https://theconversation.com/homage-to-the-forest-tree-architect-francis-kere-pays-tribute-to-his-african-roots-74332">Homage to the forest tree: Architect Francis Kéré pays tribute to his African roots</a>
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</em>
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<p>Historically, the prize honoured the designers of iconic buildings, but in the last few years this seems to have changed. In 2021 a <a href="https://www.theguardian.com/artanddesign/2021/mar/16/lacaton-vassal-unflashy-french-architectures-pritzker-prize">French duo Lacaton & Vassal</a> were recognised for their advocacy of social justice and sustainability. In 2016 the Chilean <a href="https://www.pritzkerprize.com/laureates/ale-jan-dro-ara-ve-na">Alejandro Aravena</a> won the award for his design of several social housing projects and in <a href="https://www.dezeen.com/2014/03/24/shigeru-ban-wins-pritzker-prize-2014/">2014 it was awarded to</a> Japanese architect Shigeu Ban. Besides creating architecture, Shigeu Ban also volunteers for disaster relief.</p>
<h2>Why does Kéré’s win matter?</h2>
<p>In these convoluted times, Kéré’s work is a magnificent example of the potential of architecture to provide a better future and to catalyse progress on a local scale. His <a href="https://www.instagram.com/kerearchitecture/?hl=en">projects</a> show how the architect’s role is not just to design walls, doors, windows and roofs – although he does all of those too, with great quality, elegance, rigour and beauty. His work shows strong climate and budget concerns, along with the will to engage local communities in the design and construction of the buildings themselves.</p>
<p>Kéré’s work suggests that only once buildings are inhabited can we know if their architecture truly suits them. For instance, an oversailing metal roof which provides shade from the brutal sun and protects the walls from the rain might become an unintended playground for children, who like to climb roofs as if they were trees. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/453324/original/file-20220321-25-80bqjk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453324/original/file-20220321-25-80bqjk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=350&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453324/original/file-20220321-25-80bqjk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=350&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453324/original/file-20220321-25-80bqjk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=350&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453324/original/file-20220321-25-80bqjk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=440&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453324/original/file-20220321-25-80bqjk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=440&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453324/original/file-20220321-25-80bqjk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=440&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The design of London’s 2017 Serpentine Pavilion was commissioned from Kéré.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>His sensibility for using local resources and adapting buildings to their surroundings has become an inspiration for many other architects.</p>
<h2>How could Kéré’s work make the world a better place?</h2>
<p>Kéré’s work resonates on a global scale. His buildings are acts of social transformation. Above and beyond any architectural discourse, they create the conditions for cultivating civic responsibility and promoting self-empowerment.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/young-female-south-african-architect-reinvents-serpentine-pavilion-in-london-161444">Young female South African architect reinvents Serpentine Pavilion in London</a>
</strong>
</em>
</p>
<hr>
<p>Once again, looking back to the beginning of his career, which set the basis for his approach to architecture, Kéré’s decision to compensate the support for his childhood studies with a school building was not coincidental. He knew that as a first public institution, the school would enable the population to begin to acquire a proper civic voice – eventually becoming participants in the destiny of their village and country, instead of merely being affected by it.</p>
<p>If this vision was applied elsewhere, the world would definitely be a better place.</p><img src="https://counter.theconversation.com/content/179685/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paulo Moreira was a post-doctoral fellow in the research project Africa Habitat (2020-21), coordinated by the Faculty of Architecture, University of Lisbon, funded by FCT and Aga Khan Development Network (Knowledge for Development Initiative programme). Previously, he received a doctoral grant from FCT - Portugal (2010-2014). He owns Paulo Moreira Architectures and is the founder and artistic director of INSTITUTO, a cultural space in Porto, Portugal.
</span></em></p>Kéré shows how architecture can build better futures by embracing communities to help catalyse progress.Paulo Moreira, Researcher, Universidade de Lisboa Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1706112021-11-19T13:16:28Z2021-11-19T13:16:28ZCuba’s post-revolution architecture offers a blueprint for how to build more with less<figure><img src="https://images.theconversation.com/files/429039/original/file-20211028-19-1ndyd3h.jpg?ixlib=rb-1.1.0&rect=5%2C118%2C3602%2C2428&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Builders construct experimental vaults of brick and cement blocks in Santiago de Cuba in December 1960.</span> <span class="attribution"><span class="source">Centro de Documentación, Empresa RESTAURA, Oficina del Historiador de la Ciudad de La Habana</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Around the world, there’s a conjoined crisis of climate change and housing shortages – two topics at the <a href="https://www.insidehousing.co.uk/comment/comment/cop26-climate-change-and-why-housing-matters-73166">top of the list of discussions</a> in the recent <a href="https://ukcop26.org/">COP26 climate summit</a> in Glasgow. </p>
<p>Construction and buildings <a href="https://unhabitat.org/the-climate-is-changing-so-must-our-homes-how-we-build-them">account for more than one-quarter of global greenhouse gas emissions</a>. Meanwhile, according to a September report by Realtor.com, the U.S. alone <a href="https://www.cnbc.com/2021/09/14/america-is-short-more-than-5-million-homes-study-says.html">is short 5.24 million homes</a>.</p>
<p>Addressing both crises will require building structures <a href="https://www.theguardian.com/cities/2020/jan/15/the-case-for-making-low-tech-dumb-cities-instead-of-smart-ones">more sustainably</a> and <a href="https://www.designworldonline.com/abb-robotics-advances-construction-industry-automation-to-enable-safer-and-sustainable-building/">more efficiently</a>.</p>
<p>But this isn’t the first time architects and governments have had to deal with dwindling resources and the task of housing large numbers of people. <a href="https://www.pbs.org/wgbh/americanexperience/features/post-revolution-cuba/">In 1959</a>, an armed revolt led by Fidel Castro ousted Cuba’s military dictatorship of Fulgencio Batista. As part of a broader plan to improve the quality of life for millions of Cubans, Castro’s new government sought to develop a program to mass-produce new housing, schools and factories.</p>
<p>In the years that followed, however, this dream clashed with difficult realities. Sanctions and supply chain disruptions had created a shortage of conventional building materials.</p>
<p>Architects realized they needed to do more with less and invent new construction methods using local materials.</p>
<h2>A thousand-year-old technique</h2>
<p><a href="https://doi.org/10.1525/jsah.2021.80.3.321">In an article</a> that I co-authored with architect and engineer <a href="https://www.arct.cam.ac.uk/people/mhr29%40cam.ac.uk">Michael Ramage</a> and architect <a href="https://orcid.org/0000-0002-1406-4588">Dania González Couret</a>, we explored the creative challenges of this period by focusing on a specific structural element that these Cuban architects soon seized upon: the tile vault.</p>
<p><a href="https://doi.org/10.2307/988501">Tile vaulting</a> is a technique that flourished in the eastern Mediterranean <a href="https://www.academia.edu/46049241/2021_BRICK_CONSTRUCTION_IN_ALMORAVID_MARRAKECH_THE_QUBBAT_AL_BARUDIYYIN">after the 10th century</a>. </p>
<p>It involves constructing arched ceilings made of multiple layers of lightweight terra cotta tiles. To build the first layer, the builders use fast-setting mortar to glue the tiles together with barely any temporary support. Afterward, the builder adds more layers with normal cement or lime mortar. This technique doesn’t require expensive machinery or use of a lot of timber for formwork. But speed and craftsmanship are paramount.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429024/original/file-20211028-26-1rirswx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Pencil drawings of different arches." src="https://images.theconversation.com/files/429024/original/file-20211028-26-1rirswx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429024/original/file-20211028-26-1rirswx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=266&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429024/original/file-20211028-26-1rirswx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=266&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429024/original/file-20211028-26-1rirswx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=266&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429024/original/file-20211028-26-1rirswx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=334&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429024/original/file-20211028-26-1rirswx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=334&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429024/original/file-20211028-26-1rirswx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=334&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Three types of vaults – clockwise, from top left: conventional stone, tiled dome and tiled vault.</span>
<span class="attribution"><a class="source" href="https://oa.upm.es/38027/">Luis Moya Blanco</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Because of its affordability and durability, tile vaulting spread <a href="https://researchportal.vub.be/en/publications/the-construction-of-tile-vaults-in-belgium-1900-1940-contractors">to different parts of Europe</a> and <a href="https://papress.com/products/guastavino-vaulting-the-art-of-structural-tile">the Americas</a>. It became known as <a href="https://sap.mit.edu/article/standard/guastavino-vaulting-art-structural-tile">Guastavino tiling</a> in the U.S – a nod to Spanish architect Rafael Guastavino, who used the technique in <a href="https://savingplaces.org/stories/7-majestic-guastavino-tile-vaults-from-around-the-country#.YZS4P9BBzIU">over 1,000 projects in the U.S.</a>, including the Boston Public Library and New York’s Grand Central Station. </p>
<h2>Vaults in vogue</h2>
<p>In Cuba, tile vaults were famously used to build the National Art Schools, or Escuelas Nacionales de Arte. </p>
<p>Fidel Castro advocated for the construction of the five schools on what, before the revolution, had been a golf course in Cubanacán, a town west of Havana. </p>
<p>Designed by Ricardo Porro, Vittorio Garatti and Roberto Gottardi, the <a href="https://papress.com/products/revolution-of-forms-updated-edition-cubas-forgotten-art-schools">schools integrate terra cotta shells and arches with the site’s green landscape</a>. They were long thought to be the only tile vault buildings in post-revolution Cuba. </p>
<p>However, we discovered that the National Art Schools are only the tip of the iceberg. From 1960 to 1965, a range of vault experiments and projects took place across the country. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429025/original/file-20211028-13-11t51l9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Black and white photo of an open air arched building." src="https://images.theconversation.com/files/429025/original/file-20211028-13-11t51l9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429025/original/file-20211028-13-11t51l9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429025/original/file-20211028-13-11t51l9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429025/original/file-20211028-13-11t51l9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429025/original/file-20211028-13-11t51l9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429025/original/file-20211028-13-11t51l9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429025/original/file-20211028-13-11t51l9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The School of Ballet by Vittorio Gratti, one of the five vaulted National Art Schools in Havana.</span>
<span class="attribution"><span class="source">M. Wesam Al Asali</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Shortly after the revolution, architects and engineers at the Ministry of Construction – known as MICONS – went to Camagüey, a province known for its terra cotta brick-making, to learn more about the craft. One of these architects, Juan Campos Almanza, then a recent graduate of the University of Havana, led the research team. As an experiment, he built a load-bearing vault on the grounds of the Azorin brick factory. </p>
<p>It was a success. He went on to use the design to construct affordable and elegant beachfront homes in Santa Lucía, north of Camagüey, using the same vault design.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429026/original/file-20211028-19-13u43mb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Vaulted homes lined up side by side." src="https://images.theconversation.com/files/429026/original/file-20211028-19-13u43mb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429026/original/file-20211028-19-13u43mb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=194&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429026/original/file-20211028-19-13u43mb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=194&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429026/original/file-20211028-19-13u43mb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=194&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429026/original/file-20211028-19-13u43mb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=243&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429026/original/file-20211028-19-13u43mb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=243&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429026/original/file-20211028-19-13u43mb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=243&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Juan Campos Almanza’s beachfront homes were built based on a vaulting experiment that took place in 1960.</span>
<span class="attribution"><span class="source">Documentation Center, Office of the Historian of Havana</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>The best of both worlds</h2>
<p>Brick-and-tile vault construction appeared to be a promising solution to build replicable and cost-effective ceilings. </p>
<p>The Center of Technical Investigations, an agency tasked with developing housing, schools and factories, used Almanza’s research to construct its own vaulted offices. An outdoor space nearby – famously called “El Patio del MICONS” – became a staging ground for more structural experiments.</p>
<p>In El Patio, craftspeople, engineers and architects worked together to develop affordable vaulted buildings, while teachers at El Patio’s tile masons’ school taught building techniques to cohorts of apprentices.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429033/original/file-20211028-25-hbesj8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/429033/original/file-20211028-25-hbesj8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429033/original/file-20211028-25-hbesj8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=478&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429033/original/file-20211028-25-hbesj8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=478&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429033/original/file-20211028-25-hbesj8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=478&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429033/original/file-20211028-25-hbesj8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=601&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429033/original/file-20211028-25-hbesj8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=601&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429033/original/file-20211028-25-hbesj8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=601&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Builders practice putting together a vaulted roof in the Patio del MICONS in 1961.</span>
<span class="attribution"><span class="source">Documentation Center, Office of the Historian of Havana</span></span>
</figcaption>
</figure>
<p>Vaulted buildings and homes soon started cropping up across the country. In 1961, Juan Campos Almanza completed his first housing projects in Altahabana, a new neighborhood located near Havana, building simple barrel vaults on prefabricated beams. Similar designs were used for more beachfront houses, schools and factories.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/429036/original/file-20211028-17-1ui2vdc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429036/original/file-20211028-17-1ui2vdc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=486&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429036/original/file-20211028-17-1ui2vdc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=486&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429036/original/file-20211028-17-1ui2vdc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=486&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429036/original/file-20211028-17-1ui2vdc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=611&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429036/original/file-20211028-17-1ui2vdc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=611&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429036/original/file-20211028-17-1ui2vdc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=611&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Architect Mario Girona built a vaulted elementary school in Marianao, Cuba.</span>
<span class="attribution"><span class="source">Documentation Center, Office of the Historian of Havana</span></span>
</figcaption>
</figure>
<p>In his report about the Altahabana pilot project, Campos defined his method as “tradicional mejorado,” or “improved traditional construction” – a mix of conventional building methods with some prefabricated elements. </p>
<p>This way, he argued, builders could gain the best of both worlds: The construction, some of it built by hand, was fast and replicable. And it didn’t require a lot of materials and preexisting infrastructure.</p>
<p>The best example of this construction method is the vaulted Pre-University Center at Liberty City, the site of a former U.S. Army base. The structure was designed in 1961 by Josefina Rebellón, who at the time was a third-year architecture student. </p>
<p>Only a couple of miles from the Schools of Art, Rebellón’s design was completed in 18 months. It was made up of two circular vaulted buildings, with conical vaults and prefabricated beams, with an undulating two-story classroom building between the two circles.</p>
<figure class="align-center ">
<img alt="Bird's-eye drawing of two circular buildings" src="https://images.theconversation.com/files/432083/original/file-20211115-13-1bgtdne.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/432083/original/file-20211115-13-1bgtdne.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=378&fit=crop&dpr=1 600w, https://images.theconversation.com/files/432083/original/file-20211115-13-1bgtdne.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=378&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/432083/original/file-20211115-13-1bgtdne.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=378&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/432083/original/file-20211115-13-1bgtdne.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=475&fit=crop&dpr=1 754w, https://images.theconversation.com/files/432083/original/file-20211115-13-1bgtdne.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=475&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/432083/original/file-20211115-13-1bgtdne.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=475&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A sketch of Josefina Rebellón’s Pre-University Center.</span>
<span class="attribution"><span class="source">Documentation Center, Office of the Historian of Havana</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A brief experiment with a lasting legacy</h2>
<p>These exciting new construction methods didn’t last long. </p>
<p>In 1963, Havana hosted the conference for the International Union of Architects. That year’s theme was <a href="https://www.uia-architectes.org/webApi/en/congress/havana-1963.html">Architecture in Developing Countries</a>.</p>
<p>The conference gave Cuban architects an opportunity to reflect on their recent experiences. The Ministry of Construction pushed to end what it viewed as a period of experimentation; mass housing, they argued, demanded industrialized construction.</p>
<p>Buildings started being made in factories and then assembled on site. Skilled and specialized labor, like vault-building, was no longer seen as an asset but an obstacle, since vault builders were difficult to find in the country’s remote areas, and novice builders required extensive training.</p>
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<p>Yet the story of these buildings offers lessons for designing with scarcity. </p>
<p>The ability to experiment is important. Coordination among builders, governments and architects is crucial. And craftsmanship matters, too, whether it’s tile vaulting or <a href="https://practicalpreservationservices.com/traditional-joinery-what-it-is-and-why-is-it-important-in-preservation/">traditional carpentry</a>. </p>
<p>For too long, buildings that required craftsmanship have been thought of as overly expensive pet projects that deployed techniques better suited for a different era. But the Cubans were able to show that craftsmanship can be developed, scaled up and combined with technological advances.</p>
<p>Today, a handful of promising initiatives show how the craft of tile vaulting can serve for the <a href="https://architizer.com/projects/rwanda-cricket-stadium/">low-carbon construction of buildings</a> or engineered <a href="https://block.arch.ethz.ch/brg/research/rib-stiffened-funicular-floor-system">ceiling systems</a>. Back in Cuba, tile vaulting is now being taught in the <a href="http://www.eusebioleal.cu/noticia/se-crea-aula-taller-eusebio-leal-spengler/">Escuela Taller Gaspar Melchor</a>, a training center in Havana’s historical center.</p>
<p>Cuba’s vaulted architecture reflects the relationship between necessity and invention, a process that many people mistakenly think of as automatic. It isn’t. It is a relationship based on perseverance, trial and error and, above all, passion.</p>
<p>Look no further than what Juan Campos Almanza and his peers left behind on the island: beautiful, replicable buildings, many of which are still standing today.</p><img src="https://counter.theconversation.com/content/170611/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>M. Wesam Al Asali is the Lead Designer and Founder of IWlab and CERCAA.
</span></em></p>After Fidel Castro took power, government plans to build new housing, schools and factories were hindered by sanctions and supply chain issues, forcing architects to come up with creative solutions.M. Wesam Al Asali, Global Fung Postdoctoral Fellow, Princeton UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1559172021-03-01T14:58:24Z2021-03-01T14:58:24ZNuclear fusion: building a star on Earth is hard, which is why we need better materials<figure><img src="https://images.theconversation.com/files/386645/original/file-20210226-17-10zekhe.jpg?ixlib=rb-1.1.0&rect=120%2C86%2C3702%2C2006&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Inside a tokamak fusion reactor.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/high-energy-particles-flow-through-tokamak-1788905414">Shutterstock/dani3315</a></span></figcaption></figure><p>Nuclear fusion is the process that <a href="https://theconversation.com/curious-kids-what-does-the-suns-core-look-like-141785">powers the Sun</a> and all other stars. During fusion, the nuclei of two atoms are brought close enough together that they fuse together, releasing huge amounts of energy.</p>
<p>Replicating this process on Earth has the potential to deliver <a href="https://theconversation.com/why-nuclear-fusion-is-gaining-steam-again-93775">almost limitless electricity</a> with virtually zero carbon emissions and greater safety, and without the same <a href="https://theconversation.com/four-things-you-didnt-know-about-nuclear-waste-134004">level of nuclear waste</a> as fission.</p>
<p>But building what is essentially a mini star on Earth and holding it together inside a reactor is not an easy task. It requires immense temperatures and pressures and extremely strong magnetic fields. </p>
<p>Right now we don’t quite have materials capable of withstanding these extremes. But researchers like me are working to develop them, and we’ve found some exciting things along the way.</p>
<h2>Tokamaks</h2>
<p>There are many ways to contain nuclear fusion reactions on Earth, but the most common uses a doughnut shaped device called a tokamak. Inside the tokamak, the fuels for the reaction – isotopes of hydrogen called deuterium and tritium – are heated until they become a plasma. A plasma is when the electrons in the atoms have enough energy to escape the nuclei and start to float around. Because it’s made up of electrically charged particles, unlike a normal gas, it can be contained in a magnetic field. This means it doesn’t touch the reactor sides – instead, it floats in the middle in a doughnut shape. </p>
<p>When deuterium and tritium have enough energy they fuse together, creating helium, neutrons and releasing energy. The plasma has to reach temperatures of <a href="https://phys.org/news/2020-12-korean-artificial-sun-world-sec-long.html">100 million degrees Celsius</a> for large amounts of fusion to happen – ten times hotter than the centre of the Sun. It has to be much hotter because the Sun has a much higher density of particles.</p>
<p>Although it’s mostly contained within a magnetic field, the reactor still has to withstand huge temperatures. At Iter, the world’s biggest fusion experiment, expected to be built by 2035, <a href="https://www.iter.org/mach/Divertor">the hottest part</a> of the machine would reach around 1,300°C. </p>
<figure class="align-center ">
<img alt="A diagram showing deuterium and tritium going into a fusion reaction, with helium, neutrons and energy coming out of it." src="https://images.theconversation.com/files/386678/original/file-20210226-17-oeoh0o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/386678/original/file-20210226-17-oeoh0o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=454&fit=crop&dpr=1 600w, https://images.theconversation.com/files/386678/original/file-20210226-17-oeoh0o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=454&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/386678/original/file-20210226-17-oeoh0o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=454&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/386678/original/file-20210226-17-oeoh0o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=570&fit=crop&dpr=1 754w, https://images.theconversation.com/files/386678/original/file-20210226-17-oeoh0o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=570&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/386678/original/file-20210226-17-oeoh0o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=570&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Deuterium tritium fusion.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/nuclear-fusion-energy-diagram-reaction-models-1501925243">Shutterstock/OSweetNature</a></span>
</figcaption>
</figure>
<p>While the plasma will mostly be contained in a magnetic field, there are times when the plasma might collide with the walls of the reactor. This can result in erosion, fuel being implanted in the walls and modifications to the material properties.</p>
<p>On top of the extreme temperatures, we also have to consider the by-products of the fusion reaction of deuterium and tritium, like extremely <a href="https://link.springer.com/article/10.1007/s10894-018-0182-1">high energy neutrons</a>. Neutrons have no charge so can’t be contained by the magnetic field. This means they hit against the walls of the reactor, causing damage. </p>
<h2>The breakthroughs</h2>
<p>All these incredibly complex challenges have contributed to huge advances in materials over the years. One of the most notable has been <a href="https://home.cern/news/series/superconductors/20-tesla-and-beyond-high-temperature-superconductors">high temperature superconducting magnets</a>, which are being used by various different fusion projects. These behave as superconductors at temperatures below the boiling point of liquid nitrogen. While this sounds cold, it’s high compared to the much colder temperatures other superconductors need. </p>
<p>In fusion, these magnets are only metres away from the high temperatures inside the tokamak, creating an enormously large temperature gradient. These magnets have the potential to generate much stronger magnetic fields than conventional superconductors, which can dramatically reduce the size of a fusion reactor and may speed up the development of commercial fusion.</p>
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Read more:
<a href="https://theconversation.com/conservative-nuclear-fusion-by-2040-pledge-is-fantasy-their-record-on-climate-change-is-too-little-too-late-124404">Conservative 'nuclear fusion by 2040' pledge is fantasy – their record on climate change is too little, too late</a>
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<p>We do have some materials designed to cope with the various challenges we throw at them in a fusion reactor. The front-runners at the moment are <a href="https://www.tandfonline.com/doi/full/10.1080/21663831.2019.1631224">reduced activation steels</a>, which have an altered composition to traditional steels so the levels of activation from neutron damage is reduced, and tungsten.</p>
<p>One of the coolest things in science is something initially seen as a potential issue can turn into something positive. Fusion is no exception to this, and one very niche but noteworthy example is the case of <a href="https://www.sciencedirect.com/science/article/pii/S2352179120300995">tungsten fuzz</a>. Fuzz is a nanostructure that forms on tungsten when exposed to helium plasma during fusion experiments. Initially considered a potential issue due to fears of erosion, there’s now research into non fusion applications, including <a href="https://pubs.acs.org/doi/pdf/10.1021/am401936q">solar water splitting</a> – breaking it down into hydrogen and oxygen.</p>
<p>However, no material is perfect, and there are several remaining issues. These include the manufacture of reduced activation materials at a large scale and the intrinsic brittleness of tungsten, which makes it a challenge to work with. We need to improve and refine on the existing materials we have. </p>
<h2>The challenges</h2>
<p>Despite the huge advances in the field of materials for fusion, there’s still a lot of work that needs to be done. The main issue is we rely on several proxy experiments to recreate potential reactor conditions, and have to try and stitch this data together, often using very small samples. Detailed modelling work helps to extrapolate predictions of material performance. It would be much better if we could test our materials in real situations.</p>
<p>The pandemic has had a major impact on materials research because it’s been more difficult to carry out real life experiments. It’s really important that we continue to develop and use advanced models to predict material performance. This can be combined with advances in machine learning, to identify the key experiments we need to focus on and identify the best materials for the job in future reactors.</p>
<p>The manufacturing of new materials has typically been in small batches, focusing only on producing enough materials for experiments. Going forward, more companies will continue to work on fusion and there will be more programmes working on experimental reactors or prototypes. </p>
<p>Because of this, we are getting to the stage where we need to think more about industrialisation and development of supply chains. As we edge closer to prototype reactors and hopefully power plants in the future, developing robust large scale supply chains will be a huge challenge.</p><img src="https://counter.theconversation.com/content/155917/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aneeqa Khan works for the University of Manchester and consults with the UKAEA. She is paid by University of Manchester and STFC. She has written this in a personal capacity and her views do not not necessarily reflect the views of any of the organisations she works for/with.</span></em></p>Building a mini star on Earth, and holding it together inside a reactor, is not an easy task.Aneeqa Khan, Research Fellow in Fusion, University of ManchesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1549812021-02-10T11:05:35Z2021-02-10T11:05:35ZTransparent wood is coming, and it could make an energy-efficient alternative to glass<figure><img src="https://images.theconversation.com/files/383275/original/file-20210209-21-13uxgyc.jpg?ixlib=rb-1.1.0&rect=73%2C30%2C3854%2C3214&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Glass windows like these could be replaced with wood.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/view-through-window-cottage-into-snowcovered-1567864882">Shutterstock/Visions-AD</a></span></figcaption></figure><p>Wood is an ancient material humans have been using for millions of years, for the construction of housing, ships and as a source of fuel for burning. It’s also a renewable source, and one way to capture excess carbon dioxide from the Earth’s atmosphere. Today, the main component of wood - cellulose – is produced annually at <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5746563/">20 times the volume of steel.</a></p>
<p>One thing you wouldn’t use wood for is making windows. Instead we rely on glass and plastic, which are transparent and, when toughened, can give structural support. But buildings lose a lot of heat through glass, and while light can bring some heat through the material, it’s not a good insulator. This is why we need double glazing. Wood, on the other hand, is highly insulating but it’s not transparent. Usually.</p>
<p>In recent years, materials scientists have been experimenting with making wood transparent. Making wood see-through, and retaining its high mechanical properties, would provide a good alternative to glass from a sustainable and renewable source. <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/adom.201800059">Previous methods</a> of doing this were highly energy intensive and used harmful chemicals, but <a href="https://advances.sciencemag.org/content/7/5/eabd7342">a new study</a> has shown a way to make wood transparent without using huge amounts of energy in the process.</p>
<h2>Seeing through wood</h2>
<p>Wood’s lack of transparency comes from the combination of its two main components, cellulose and lignin. The lignin absorbs light, and the presence of chromophores – light activated compounds – in the material makes the wood look brown. The fibres in the wood, which mainly comprise cellulose, are hollow tube-like structures. The air in these hollow tubes scatters light, further reducing the material’s transparency.</p>
<p>Previous work on making wood transparent has involved <a href="https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/cssc.201701089">removing the lignin</a> completely from the structure and replacing it with a resin material. The removal of lignin requires a lot of environmentally harmful chemicals, and it also considerably reduces <a href="https://royalsocietypublishing.org/doi/10.1098/rsta.2017.0182">the mechanical properties</a> of the material. makes it weaker. </p>
<p>The new study, by researchers at the University of Maryland, demonstrates how to make wood transparent using a simple chemical – hydrogen peroxide – commonly used to bleach hair. This chemical modifies the chromophores, changing their structure so they no longer act to absorb light and colour the wood.</p>
<figure class="align-center ">
<img alt="A sunny pine forest with logs in the foreground." src="https://images.theconversation.com/files/383279/original/file-20210209-23-1ttdei1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/383279/original/file-20210209-23-1ttdei1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/383279/original/file-20210209-23-1ttdei1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/383279/original/file-20210209-23-1ttdei1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/383279/original/file-20210209-23-1ttdei1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/383279/original/file-20210209-23-1ttdei1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/383279/original/file-20210209-23-1ttdei1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Removing a component of wood, called lignin, can make it see-through.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/forest-pine-spruce-trees-log-trunks-1552199918">Shutterstock/Krasula</a></span>
</figcaption>
</figure>
<p>The chemical can be brushed onto the wood, and then activated using light to produce a brilliant white material – blond wood if you like. The chemical reaction of wood with hydrogen peroxide is well known. It’s the basis for bleaching wood pulp used for paper making – one of the reasons why paper is brilliant white. </p>
<p>The other reason paper is white is because pores or holes in its structure scatter light, just like the hollow cellulose fibres in wood. Filling these fibres with resin reduces that scattering, allowing light to pass through the wood and making it transparent, while retaining its original mechanical properties.</p>
<h2>Wooden windows</h2>
<p>This is a very exciting development that uses well-known chemical reactions of hydrogen peroxide with lignin. The approach could also be applied to large pieces of material, leading to production of transparent building materials offering a real potential to replace glass. </p>
<p>Because the chemical is brushed onto the wood, there might be opportunities for decorative effects to be added to the material. This could make panels of material popular for indoor applications, while also offering additional insulation.</p>
<p>Further work needs to be done to optimise the reaction with wood, and to incorporate it into an industrially automated process. But one day, in the future, you might be sitting in a home or working in a building with wooden windows.</p><img src="https://counter.theconversation.com/content/154981/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steve Eichhorn receives funding from the Engineering and Physical Sciences Research Council.</span></em></p>Treating wood with bleach can make it transparent.Steve Eichhorn, Professor of Materials Science and Engineering, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1243442019-11-07T12:16:20Z2019-11-07T12:16:20ZSoft robots of the future may depend on new materials that conduct electricity, sense damage and self-heal<figure><img src="https://images.theconversation.com/files/299922/original/file-20191101-88372-1kt2aco.jpg?ixlib=rb-1.1.0&rect=262%2C34%2C1076%2C644&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Interactions between people and machines continue to increase.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/tecnalia/14109734238/">Tecnalia/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Robots used to be restricted to heavy lifting or fine detail work in factories. Now Boston Dynamics’ nimble <a href="https://www.bostondynamics.com/spot">four-legged robot, Spot</a>, is available for companies to lease to carry out various real-world jobs, a sign of just how common interactions between humans and machines have become in recent years.</p>
<p>And while Spot is versatile and robust, it’s what society thinks of as a traditional robot, a mix of metal and hard plastic. Many researchers are <a href="https://doi.org/10.1002/admt.201800477">convinced that</a> <a href="https://www.npr.org/sections/alltechconsidered/2016/12/11/504953475/behold-a-robot-hand-with-a-soft-touch">soft robots</a> capable of <a href="https://doi.org/10.1038/s41928-018-0024-1">safe physical interaction</a> with people – for example, providing in-home assistance by gripping and moving objects – will join hard robots to populate the future.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/295033/original/file-20191001-173369-1y7qpg.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/295033/original/file-20191001-173369-1y7qpg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/295033/original/file-20191001-173369-1y7qpg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=513&fit=crop&dpr=1 600w, https://images.theconversation.com/files/295033/original/file-20191001-173369-1y7qpg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=513&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/295033/original/file-20191001-173369-1y7qpg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=513&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/295033/original/file-20191001-173369-1y7qpg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=644&fit=crop&dpr=1 754w, https://images.theconversation.com/files/295033/original/file-20191001-173369-1y7qpg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=644&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/295033/original/file-20191001-173369-1y7qpg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=644&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Soft multifunctional materials will be used in soft robotics and wearable computers, for example, and will perform many different tasks simultaneously.</span>
<span class="attribution"><span class="source">Michael Ford</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Soft robotics and wearable computers, both technologies that are safe for human interaction, will demand new types of materials that are soft and stretchable and perform a wide variety of functions. My colleagues and I at the <a href="http://sml.me.cmu.edu/">Soft Machines Lab</a> at Carnegie Mellon University develop these multifunctional materials. <a href="https://www.cmu.edu/me/malen/Lab_Website/Home.html">Along with</a> <a href="https://warelab.co/people/">collaborators</a>, we’ve recently developed one such material that uniquely combines the properties of metals, soft rubbers and shape memory materials. </p>
<p>These soft multifunctional materials, as we call them, conduct electricity, detect damage and heal themselves. They also can sense touch and change their shape and stiffness in response to electrical stimulation, like an artificial muscle. In many ways, it’s what the pioneering researchers <a href="https://scholar.google.com/citations?user=Iky0yNkAAAAJ&hl=en&oi=ao">Kaushik Bhattacharya</a> and <a href="https://scholar.google.com/citations?user=gIS0-ekAAAAJ&hl=en&oi=sra">Richard James</a> described: “<a href="https://doi.org/10.1126/science.1100892">the material is the machine</a>.” </p>
<h2>Making materials intelligent</h2>
<p>This idea that the material is the machine can be captured in the concept of <a href="https://mitpress.mit.edu/books/how-body-shapes-way-we-think">embodied intelligence</a>. This term is usually used to describe a system of materials that are interconnected, like tendons in the knee. When running, tendons can stretch and relax to adapt each time the foot strikes the ground, without the need for any neural control.</p>
<p>It’s also possible to think of embodied intelligence in a single material – one that can sense, process and respond to its environment without embedded electronic devices like sensors and processing units.</p>
<p>A simple example is rubber. At the molecular level, rubber contains strings of molecules that are coiled up and linked together. Stretching or compressing rubber moves and uncoils the strings, but their links force the rubber to bounce back to its original position without permanently deforming. The ability for rubber to “know” its original shape is contained within the material structure.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/300339/original/file-20191105-88372-7sgbvn.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/300339/original/file-20191105-88372-7sgbvn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/300339/original/file-20191105-88372-7sgbvn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=277&fit=crop&dpr=1 600w, https://images.theconversation.com/files/300339/original/file-20191105-88372-7sgbvn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=277&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/300339/original/file-20191105-88372-7sgbvn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=277&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/300339/original/file-20191105-88372-7sgbvn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=349&fit=crop&dpr=1 754w, https://images.theconversation.com/files/300339/original/file-20191105-88372-7sgbvn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=349&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/300339/original/file-20191105-88372-7sgbvn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=349&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A soft robot with a stretchable and electrically conductive circuit that is self-healing.</span>
<span class="attribution"><span class="source">Soft Machines Lab</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Since engineered materials of the future that are suitable for human-machine interaction will require multifunctionality, researchers have tried to build new levels of embodied intelligence – beyond just stretching – into materials like rubber. Recently, <a href="https://doi.org/10.1038/s41563-018-0084-7">my coworkers created self-healing circuits</a> embedded in rubber.</p>
<p>They started by dispersing micro-scale liquid metal droplets wrapped in an electrically insulating “skin” throughout silicone rubber. In its original state, the skin’s thin metal oxide layer prevents the metal droplets from conducting electricity.</p>
<p>However, if the metal-embedded rubber is subjected to enough force, the droplets will rupture and coalesce to form electrically conductive pathways. Any electrical lines printed in that rubber become self-healing. <a href="https://doi.org/10.1002/adfm.201900160">In a separate study</a>, they showed that the mechanism for self-healing could also be used to detect damage. New electrical lines form in the areas that are damaged. If an electrical signal gets through, that indicates the damage.</p>
<p>The combination of liquid metal and rubber gave the material a new route to sense and process its environment – that is, a new form of embodied intelligence. The rearrangement of the liquid metal allows the material to “know” when damage has occurred because of an electrical response.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/295026/original/file-20191001-173364-8tc296.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/295026/original/file-20191001-173364-8tc296.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/295026/original/file-20191001-173364-8tc296.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/295026/original/file-20191001-173364-8tc296.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/295026/original/file-20191001-173364-8tc296.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/295026/original/file-20191001-173364-8tc296.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/295026/original/file-20191001-173364-8tc296.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/295026/original/file-20191001-173364-8tc296.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Liquid crystal elastomers are a type of shape memory material that can be programmed into a specific shape, like this 3-D face, and then reversibly transform into another shape, such as a flat sheet.</span>
<span class="attribution"><a class="source" href="https://news.rice.edu/2018/12/20/mighty-morphing-materials-take-complex-shapes/">Jeff Fitlow/Rice University</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Shape memory is another example of embodied intelligence in materials. It means materials can reversibly change to a prescribed form. Shape memory materials are good candidates for linear motion in soft robotics, able to move back and forth like your bicep muscle. But they also offer unique and complex shape-changing capabilities.</p>
<p>For example, two groups of materials scientists recently demonstrated how <a href="https://doi.org/10.1039/C8SM02174K">a class of materials</a> <a href="https://doi.org/10.1073/pnas.1804702115">could reversibly transform</a> from a flat rubber-like sheet into a 3-D topographical map of a face. It’s a feat that would be difficult with traditional motors and gears, but it’s simple for this class of materials due to the material’s embodied intelligence. The researchers used a class of materials known as liquid crystal elastomers, which are sometimes described as artificial muscles because they can extend and contract with the application of a stimulus like heat, light, or electricity.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/SpBrlmwwj30?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A new soft artificial muscle.</span></figcaption>
</figure>
<h2>Putting it all together</h2>
<p>By drawing inspiration from the liquid metal composite and the shape-morphing material, my colleagues and I recently <a href="https://doi.org/10.1073/pnas.1911021116">created a soft composite with unprecedented multifunctionality</a>.</p>
<p>It is soft and stretchable, and it can conduct heat and electricity. It can actively change its shape, unlike regular rubber. Since our composite easily conducts electricity, the shape-morphing can be activated electrically. Since it is soft and deformable, it is also resilient to significant damage. Because it can conduct electricity, the composite can interface with traditional electronics and dynamically respond to touch. </p>
<p>Furthermore, our composite can heal itself and detect damage in a whole new way. Damage creates new electrically conductive lines that activate shape-morphing in the material. The composite responds by spontaneously contracting when punctured.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/295031/original/file-20191001-173358-1ffxm3c.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/295031/original/file-20191001-173358-1ffxm3c.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/295031/original/file-20191001-173358-1ffxm3c.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=238&fit=crop&dpr=1 600w, https://images.theconversation.com/files/295031/original/file-20191001-173358-1ffxm3c.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=238&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/295031/original/file-20191001-173358-1ffxm3c.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=238&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/295031/original/file-20191001-173358-1ffxm3c.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=299&fit=crop&dpr=1 754w, https://images.theconversation.com/files/295031/original/file-20191001-173358-1ffxm3c.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=299&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/295031/original/file-20191001-173358-1ffxm3c.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=299&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Top: The damage-sensing composite is connected to a light-emitting diode to indicate that conductivity is active. When the damage is severe enough, new conductive pathways form. The new conductive pathways cause the composite to ‘respond’ by actuating. Bottom: The composite can reversibly morph in complex ways, like this dome that flattens when activated.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1073/pnas.1911021116">Ford et al, PNAS October 22, 2019 116 (43) 21438-21444</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In the movie “<a href="https://www.imdb.com/title/tt0103064/">Terminator 2: Judgment Day</a>,” the shape-shifting android T-1000 can liquify; can change shape, color, and texture; is immune to mechanical damage; and displays superhuman strength. Such a complex robot requires complex multifunctional materials. Now, materials that can sense, process and respond to their environment like these shape-morphing composites are starting to become a reality.</p>
<p>But unlike T-1000 these new materials aren’t a force for evil – they’re paving the way for soft assistive devices like prosthetics, companion robots, remote exploration technologies, antennas that can change shape and plenty more applications that engineers haven’t even dreamed up yet.</p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/124344/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Ford works for the Smart Machines Lab at Carnegie Mellon University. He receives funding from the US Army Research Office.</span></em></p>Engineers predict a time when people and robots physically interact all day long. For that to happen safely will require new soft materials that can do things like sense touch and change shape.Michael Ford, Postdoctoral Research Associate in Materials Engineering, Carnegie Mellon UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1228942019-09-13T09:44:42Z2019-09-13T09:44:42ZCould fungi save the fashion world?<p>Environmental action group Extinction Rebellion is disrupting London Fashion Week to highlight the harms of <a href="https://www.independent.co.uk/life-style/fashion/extinction-rebellion-london-fashion-week-cancel-a9101146.html">throwaway culture</a> and the concurrent climate emergency that the clothing market contributes to. Calling for the cancellation of future fashion weeks in acknowledgement of the crisis, it plans to target show venues and hold a funeral procession called “<a href="https://rebellion.earth/event/london-fashion-week-rest-in-peace/">London Fashion Week: Rest in Peace</a>”.</p>
<p>These may be new tactics but the problems with the industry have long been known. Very high water usage, pollution, a high carbon footprint and bad working conditions mean that the fashion industry, and in particular cheap cotton garments such as denim jeans, are known to be extremely environmentally and socially damaging. This is before we even consider the impact of fast fashion, inexpensive clothing produced rapidly in response to the latest trends. Such items inevitably end up in an overfull landfill site before they are even near “worn out”. </p>
<p>This is common knowledge, and so many “solutions” to this situation have been suggested. </p>
<p>Currently in vogue is the concept of “<a href="https://www.theguardian.com/fashion/2019/aug/01/slow-fashion-how-to-keep-your-favourite-clothes-for-ever-from-laundering-to-moth-proofing">slow fashion</a>”, an approach which considers the processes and resources required to make clothing and recommends that we buy quality garments that will last for longer. Another often touted option is the recommendation that we simply buy less, something encouraged by the protest groups involved in “<a href="http://www.buynothingday.co.uk/">Buy Nothing Day</a>” and initiatives such as Oxfam’s “<a href="https://oxfamapps.org/secondhandseptember/">Second Hand September</a>”.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1168095655342092289"}"></div></p>
<h2>Designing a way out</h2>
<p>Attempting to reduce the demand for new clothes is certainly going to be an important part of a more sustainable future. But what this ignores is the fact that the fashion industry is not a system that is about need. Rather, it is driven by desire, aspiration, gender politics and celebrity culture. Changing behaviour – by encouraging consumers to stop buying new things at all – would, to us, seem more immediately difficult and multifaceted than creating an alternative, aesthetically viable material solution.</p>
<p>But this does not seem to be reflected in most design attempts so far to create sustainable, circular fashion. Take the rise of “fair trade fashion” and organic cotton, for example. In our view, most of these purportedly sustainable alternatives do not seem to be able to tackle the complexity of the fashion system or the different components of it adequately. Organic cotton is still environmentally harmful and the price of “fair trade” fashion is often prohibitively expensive for many consumers. </p>
<p>Another recent design trend is the use of electronics and “<a href="https://www.researchgate.net/publication/299380509_Crafting_Smart_Textiles_-_a_meaningful_way_towards_societal_sustainability_in_the_fashion_field">smart materials</a>” to make garments interactive and more engaging, supposedly giving them longevity. But there is little research into how such textiles may be disposed of – and they are not likely to be cheap, either.</p>
<p>As such, we feel that materials that are already abundant in nature offer the best alternatives. Think of polylactic acid (PLA), a substance made from vegetable starch and already used to make biodegradable carrier bags but have the potential to be <a href="https://bioplasticsnews.com/2017/08/04/bio-sourced-biodegradable-pla-fibres-polyester-textiles/">developed into textiles</a>. Or Tencel and Lyocell, materials that are made from sustainable wood pulp and are already on the market. </p>
<p>Then there’s anything made from collagen, “animal protein” and a natural polymer, which although not so popular with vegans, has been developed into “<a href="https://edition.cnn.com/2018/10/04/business/modern-meadow/index.html">Zoa</a>”, a luxury leather alternative by Modern Meadow, and <a href="https://www.tandfonline.com/doi/abs/10.1080/20511787.2018.1449073">our own experiments</a> working with waste materials. Sustainable materials of this kind are what we should be focusing on.</p>
<h2>Mushroom materials</h2>
<p>Particularly exciting are the growing number of companies producing mushroom alternatives to packaging, building materials and leather. Stella McCartney, for example, is collaborating with Bolt Threads on a “Mylo” mushroom leather range of accessories. </p>
<p>There are several projects and companies working in this area and their outputs are diverse and inventive. Of particular note are <a href="https://www.mycoworks.com/">MycoWorks</a>, who have created “a new kind of leather grown rapidly from mycelium and agricultural by-products in a carbon-negative process”. They say that the material is sustainable, versatile, and animal–free. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/BqzrJ0AHXVf/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p><a href="https://www.lifegate.com/people/lifestyle/muskin-leather-mushrooms">MuSkin</a>, another leather alternative, is made out of <em>Phellinus ellipsoideus</em>, a fungus that rots wood in subtropical forests. Meanwhile, <a href="https://ecovativedesign.com/textiles">Ecovative Design</a>, who started out making an alternative to plastic packaging but have branched out into creating leather and foam from mycelium. </p>
<p>And in a similar area – not using fungi but microbes – is leather made from the cellulosic scoby bacteria that is used in the making of kombucha tea. There are lots of companies experimenting with this technique, such as <a href="https://www.dezeen.com/2014/02/12/movie-biocouture-microbes-clothing-wearable-futures/">Biocouture</a>. This material, when dried out, looks like a clear, pale brown leather with a flexible plastic texture.</p>
<p>We have our own experience in this field: a couple of years ago we collaborated on an attempt to make a material out of mushrooms. We grew our material from the vegetable waste from a tuber-derived cellulose powder product made by a <a href="https://www.cellucomp.com/">company in Scotland</a>. We wanted to create a location-specific fungal material, differing from the other current projects mentioned.</p>
<p>Our initial samples looked and had the texture and appearance of furry burnt crisps: it was clear we weren’t going to grow jeans or undermine the denim industry in the short space of time we had. But this objective and passion for the possibilities of mycelium in this context has stayed with us, and we are not the only ones. </p>
<p>The benefits of growing a textile-like material from fungi or bacteria as opposed to cotton, man-made fabrics or worse still, blends such as “poly-cotton” are many. Fungi are naturally abundant in nature, quick to grow (on a range of waste materials) and their growth uses a lot less water than traditional textile manufacture. In theory, a fungal product is also completely biodegradable, can be strong, can be colourful, water repellent, can be edible, and can have medicinal properties. And the list <a href="https://www.youtube.com/watch?v=XI5frPV58tY">goes on</a>.</p>
<p>As a way to disrupt the fashion system as a whole, fungi or bacteria based textile alternatives might still be some way off. But while the over consumption and toxic wastefulness of the fashion and traditional textile industry continues, design in this area can also be seen as an act of environmental protest.</p><img src="https://counter.theconversation.com/content/122894/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sam Vettese works for The Scottish Leather Group (on a research project). She receives funding from Interface, The Scottish Leather Group and The Scottish Institute for Remanufacture. </span></em></p><p class="fine-print"><em><span>Ian Singleton receives funding from Interface. </span></em></p>There is no solution to the unethical, unsustainable fashion industry – yetSam Vettese, Senior Lecturer in Applied Art and Design, Edinburgh Napier UniversityIan Singleton, Professor in Environmental Microbiology, Edinburgh Napier UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1007122018-09-18T10:48:38Z2018-09-18T10:48:38ZTrump should wage a war on waste instead of battling the world over trade<figure><img src="https://images.theconversation.com/files/236767/original/file-20180917-158213-63ervb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Instead of fighting other countries, we should be fighting our overflowing landfills.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/truck-working-landfill-birds-looking-food-169420184?src=tBJTZucNQ5HHgAxz1sDUug-1-14">Huguette Roe/shutterstock.com</a></span></figcaption></figure><p>President Donald Trump is fighting the wrong fight in his ongoing <a href="https://theconversation.com/us/topics/trade-wars-50746">trade war</a> with the rest of the world. </p>
<p>That’s because it’s premised on the old-school notion of the linear economy in which someone in another country, such as China, digs up raw materials and sends them to a factory, where they get turned into the finished product and shipped to the U.S. In exchange, <a href="https://www.washingtonpost.com/business/2018/08/03/trump-hates-trade-deficit-its-track-be-biggest-decade/?noredirect=on&utm_term=.83c540dd4382">money leaves the U.S. economy</a> and flows to the countries where the product was made – creating the <a href="https://www.nytimes.com/2018/03/05/us/politics/trade-deficit-tariffs-economists-trump.html">trade deficit Trump despises</a>.</p>
<p>And here’s the important bit. Americans use the product for a while, throw it away, and it ends up in a dump. And then we buy another import. </p>
<p>The long-term effect? Our money goes to a foreign economy, and Americans end up with piles of garbage. Then we pay <a href="https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=2ahUKEwi76bT9hLvdAhVyc98KHbDWB7sQFjABegQIBRAB&url=https%3A%2F%2Fwww.omicsonline.org%2Fopen-access%2Feffects-of-electronic-waste-on-developing-countries-2475-7675-1000128.php%3Faid%3D88750&usg=AOvVaw3M_1XDBboG9MhanJSttUSG">a foreign economy one more time to take the garbage off our hands</a>. China is one country that used to take a lot of our garbage, but <a href="https://www.sciencedirect.com/science/article/pii/S1364032115011855">India, Pakistan and Nigeria</a> are also big in this business. </p>
<p>A circular economy, by contrast, starts with the finished product, which can then be recycled domestically and reused, often at <a href="http://circularfoundation.org/sites/default/files/tce_report1_2012.pdf">a fraction of the cost of manufacturing them new elsewhere</a>. This <a href="http://circularfoundation.org/sites/default/files/tce_report1_2012.pdf">keeps the money at home</a>, which produces more domestic jobs and wealth. </p>
<p>As a researcher of corporate social responsibility, <a href="https://doi.org/10.1007/978-3-319-66023-3_178">I’ve been exploring</a> whether consumers are willing to buy more goods that have been remanufactured. My research suggests the answer is yes – if companies can figure how to produce more of them. And that’s where Trump and the federal government could play a big role. </p>
<h2>Companies leading the charge</h2>
<p>For now, companies and others in the American private sector are trying to lead the way, such as construction and mining equipment maker Caterpillar and automaker General Motors.</p>
<p>Caterpillar, for example, currently <a href="https://www.rit.edu/research/sites/rit.edu.research/files/research-magazines/RIT-Research-Magazine-Spring-Summer-2018.pdf">remanufactures 85 million tons</a> of material a year, while GM has 142 manufacturing and other facilities <a href="http://media.gm.com/media/us/en/gm/news.detail.html/content/Pages/news/us/en/2018/feb/0228-landfill-free.html">that don’t produce any garbage</a> by recycling, reusing or converting all waste to energy. GM also participates in a new <a href="https://pathway21.com/about-2/">online exchange</a> that has about 1,000 partner companies buying and selling their recycled waste as raw material. </p>
<p>The nonprofit sector has also been playing a role, both in terms of research and practical efforts. Since 1991, the <a href="https://www.rit.edu/gis/remanufacturing/">Center for Remanufacturing and Resource Recovery</a> at my own Rochester Institute of Technology in upstate New York, for example, has been working with organizations such as the U.S. Marines Corps and Staples to take advantage of circular economy principles. </p>
<p>The center helped the Marines <a href="https://www.rit.edu/research/sites/rit.edu.research/files/research-magazines/RIT-Research-Magazine-Spring-Summer-2018.pdf">remanufacture defective drive shafts</a> for light armored vehicles, which has saved the military force 78 percent versus the cost of buying them new. It also partnered with Staples to cut the use of non-recycled materials in office furniture by almost 90 percent while reducing the cost to the customer by over 40 percent. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/236766/original/file-20180917-158228-1acaf2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/236766/original/file-20180917-158228-1acaf2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/236766/original/file-20180917-158228-1acaf2r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/236766/original/file-20180917-158228-1acaf2r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/236766/original/file-20180917-158228-1acaf2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/236766/original/file-20180917-158228-1acaf2r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/236766/original/file-20180917-158228-1acaf2r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The U.S. could reuse more of their plastics, like Kenya did when they sailed the first dhow boat made entirely of recycled plastic.</span>
<span class="attribution"><a class="source" href="http://pictures.reuters.com/C.aspx?VP3=SearchResult&VBID=2C0FCIB6AB2MS&SMLS=1&RW=1264&RH=744&POPUPPN=6&POPUPIID=2C0FQEQ5SKOCG">Reuters/Baz Ratner</a></span>
</figcaption>
</figure>
<h2>Benefits of circular logic</h2>
<p>The benefits can add up quickly. </p>
<p>General Motors, for example <a href="https://www.greenbiz.com/article/materials-matchmaking-how-gm-drives-1-billion-annual-revenue">boasts revenue and savings</a> of US$1 billion a year from its circular economy initiatives. </p>
<p>That’s just one company. Scaling up could yield over <a href="http://thebusinessleadership.academy/wp-content/uploads/2016/03/Circular_economy.pdf">$1 trillion a year</a> in savings globally – and that’s just in terms of mining and processing fewer raw materials. More broadly, were the European Union, for example, to replace all its imports with locally reused or recycled alternatives, it alone <a href="http://circularfoundation.org/sites/default/files/tce_report1_2012.pdf">could generate</a> $300 billion to $600 billion a year in savings, according to a 2012 report by the Ellen MacArthur Foundation, a U.K. charity focused on promoting the transition to a circular economy. </p>
<p>Remanufacturing in the U.S. is already responsible for <a href="https://www.rit.edu/gis/remanroadmap/docs/Technology%20roadmap%20for%20remanufacturing%20in%20the%20circular%20economy.pdf">180,000 jobs across sectors</a> as diverse as aerospace, consumer products, office furniture and retreaded tires. Given how much the <a href="https://www.bea.gov/data/intl-trade-investment/international-trade-goods-and-services">U.S. currently imports from abroad</a> – and that remanufacturing is still less than 2 percent of total manufacturing in the U.S. – there’s room to create hundreds of thousands more jobs. </p>
<h2>How Trump could help</h2>
<p>While there are many ways the U.S. government could marshal its tremendous resources behind this effort, there are two in particular I think would pay dividends. </p>
<p>Both revolve around a core problem in remanufacturing: Most things we currently make <a href="https://www.rit.edu/gis/remanroadmap/docs/Technology%20roadmap%20for%20remanufacturing%20in%20the%20circular%20economy.pdf">can’t be remanufactured</a>. That’s partly because of social barriers — customers may confuse remanufactured with used, which is a very different thing — and partly because they’re not made to be remanufactured.</p>
<p>Plastics in particular pose a significant problem to moving toward a circular economy. Globally, <a href="http://www.doi.org/10.1126/sciadv.1700782">we only recycle or reuse</a> about 9 percent of the plastic produced each year, with 79 percent going to landfills and 12 percent being burned. </p>
<p>Trump could support two ways to help solve this problem. Basically, with a carrot and a stick. The carrot involves setting a standard of design to ensure all products are made with future use in mind, as well as using his influence to encourage Americans to buy goods remanufactured in the U.S.</p>
<p>The stick is tax policy. Specifically, the government could tax products that can’t be converted into raw materials after they are used, as well as those that are made with less than a certain percentage of reused components – a minimum that would be set to gradually increase. Money raised through this tax could be used to support research into remanufacturing, community efforts to reach higher recycling and reuse targets, or other purposes.</p>
<h2>Remanufacturing for the win</h2>
<p>Some countries are already reducing their imports by going circular, putting the United States at risk of falling behind.</p>
<p>China, for one, <a href="https://doi.org/10.1111/jiec.12597">has been systematically expanding</a> its efforts in this area for over 20 years, while the <a href="https://doi.org/10.1111/jiec.12597">EU is beginning</a> to invest in a circular economy as well with a formal action plan, <a href="http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:52015DC0614">most recently revised in 2015</a>.</p>
<p>In an entirely circular economy, the U.S. would most likely still import stuff from abroad, such as steel from China. But that steel would wind up being <a href="https://www.greenbiz.com/article/materials-matchmaking-how-gm-drives-1-billion-annual-revenue">reused in American factories</a>, employing tax-paying American workers to manufacture new goods. </p>
<p>In other words, the more circular Americans make their economy, the fewer products they’ll wind up importing and the more things that could bear the “Made in the USA” label.</p><img src="https://counter.theconversation.com/content/100712/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clyde Hull is a Professor of Management at the Saunders College of Business at RIT. He is also an associate faculty member of RIT’s Golisano Institute for Sustainabilty, which includes the Center for Remanufacturing and Resource Recovery. He is not involved in the Center’s operations.</span></em></p>Trump’s plan to slap $200 billion more in tariffs on Chinese goods is premised on yesterday’s waste-fueled economy. Tomorrow’s economy is ‘circular.’Clyde Eiríkur Hull, Professor of Management, Rochester Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/828312018-01-09T19:37:46Z2018-01-09T19:37:46ZCurious Kids: Why can some cups go in the microwave and some not?<figure><img src="https://images.theconversation.com/files/198472/original/file-20171211-27714-uyn8cp.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The short answer is that it depends on the material the cups and plates are made of, and even what shape they are.</span> <span class="attribution"><span class="source">Marcella Cheng/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p><em>This is an article from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!</em> </p>
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<p><strong>Why can some cups go in the microwave and some not? What happens if you put the wrong cup or plate in the microwave? – Edie, age 8, Melbourne.</strong> </p>
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<p>Good question, Edie! </p>
<p>The short answer is that it depends on the material the cups and plates are made of, and even what shape they are. </p>
<p>Microwave ovens heat up the food from the inside – using what scientists call “microwaves”. </p>
<h2>What are microwaves?</h2>
<p>Microwaves are a kind of electromagnetic radiation – just like sunlight, radio waves, and x-rays (like the ones they use to take photos of bones in hospitals).</p>
<p>When you put your food in a microwave oven, the microwaves make the water molecules in the food vibrate or jiggle around really fast. This is how the food heats up. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-if-a-huge-huntsman-spider-is-sucked-into-a-vacuum-cleaner-can-it-crawl-out-later-77390">Curious Kids: If a huge huntsman spider is sucked into a vacuum cleaner, can it crawl out later?</a>
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<h2>Why are metals dangerous?</h2>
<p>Putting metal in the microwave oven is generally a bad idea. In metals, the electrons – the tiny, negatively charged parts of the atoms – are free to move around. This is why metals conduct electricity, meaning they can carry electricity from one point to another. </p>
<p>The microwaves push and pull the electrons around. With metallic objects that have sharp edges or tips – like aluminium foil or forks – the electrons can build up on the tips. This can lead to sparks and fire. </p>
<p>Other metallic objects may not spark but they can get very hot. That can also lead to a fire depending on what else is inside the microwave.</p>
<p><img width="100%" src="https://media.giphy.com/media/l3mZsuP4R5wPRJnUc/giphy.gif"></p>
<h2>What materials are microwave safe?</h2>
<p>Materials like plastic, glass or ceramics are usually safe to use in the microwave because they don’t contain water and the electrons aren’t free to move around. But we still need to be careful: some plastic containers are too thin and can melt or release plastic into the food. </p>
<p>The bottom line is: it’s hard to tell exactly how something will behave inside a microwave without testing, so the rule of thumb is to only use containers that have been tested and are known to be microwave-safe.</p>
<h2>What about the metal grate on the inside of the microwave door?</h2>
<p>You’re right! There is a metal grate on the inside of the metal door, with tiny holes in it. I’ll explain why it’s there and why that metal grate doesn’t cause sparks or fire. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/183701/original/file-20170829-23262-18ap31t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/183701/original/file-20170829-23262-18ap31t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/183701/original/file-20170829-23262-18ap31t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183701/original/file-20170829-23262-18ap31t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183701/original/file-20170829-23262-18ap31t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183701/original/file-20170829-23262-18ap31t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183701/original/file-20170829-23262-18ap31t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183701/original/file-20170829-23262-18ap31t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">There is a metal grate on the inside of the microwave door.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/david55king/2168539444/in/photolist-4iCke7-4UZCcC-nw5eXn-7JCjGq-7uC4v8-4f65N4-4UZBJY-bUDDeo-dQKTC6-3pCvgL-a4twUJ-9qJ1yc-5AcfTd-8Yu6SJ-indRF-agK3GR-f9nh3Z-8b82ds-qGej85-95bFQF-dD7wZD-6eFdQ4-6jpPMv-8YuTzy-cht11A-9iCJBh-8Yop38-owRDm-dzERHs-4Hs7sD-8eiRQG-4Ut6u2-4UVt8p-8AHe9z-7AkpHi-nAGJ7M-qNFinB-StSst-aseJX7-4xBjka-2VynCp-hkSoZS-fHUQCV-59TbCN-7v59aA-cv66bq-xAk2n-4UVq4T-6CCQiE-6dYRiE">Flickr/David King</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Electromagnetic radiation – like sunlight, x-rays and microwaves – all differ in their “wavelengths”. Like waves on the ocean, this is the distance between the peaks of the waves. </p>
<p>Sunlight and microwaves only differ by how far apart are the peaks of the wave. For light, this distance between peaks, that we call the “wavelength”, is very tiny – a thousand times smaller than the width of a hair.</p>
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<strong>
Read more:
<a href="https://theconversation.com/health-check-is-it-safe-to-microwave-your-food-66776">Health check: is it safe to microwave your food?</a>
</strong>
</em>
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<p>In a typical microwave oven, the wavelength is much larger – about 12cm. This is why they have small holes (of about 1mm) on a metal plate in the door. </p>
<p>The wavelength of light is smaller than the holes and it can get out (so we can see inside), but the wavelength of the microwaves is too big for the hole and they bounce off the metal plate. The microwaves cannot escape.</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:</em></p>
<p><em>* Email your question to curiouskids@theconversation.edu.au
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* Tell us on <a href="https://twitter.com/ConversationEDU">Twitter</a> by tagging <a href="https://twitter.com/ConversationEDU">@ConversationEDU</a> with the hashtag #curiouskids, or
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em>Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/82831/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eric Cavalcanti does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Have you ever been told not to put metal in the microwave? Edie, age 8, wants to know why.Eric Cavalcanti, Senior Lecturer, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/863782017-10-26T21:22:44Z2017-10-26T21:22:44ZHow quantum materials may soon make Star Trek technology reality<figure><img src="https://images.theconversation.com/files/192105/original/file-20171026-13298-9jyeex.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Strange new materials that propel the fictional Star Trek universe are being developed by scientists in reality today. Above, the USS Discovery accelerates to warp speed in an artist's rendition for the TV series Star Trek Discovery.
</span> <span class="attribution"><span class="source">(Handout)</span></span></figcaption></figure><p>If you think technologies from Star Trek seem far-fetched, think again. Many of the <a href="https://tricorder.xprize.org/">devices</a> from the acclaimed television series are slowly becoming a <a href="https://www.theguardian.com/technology/gallery/2009/may/15/star-trek-technology">reality</a>. While we may not be <a href="http://www.bbc.com/news/science-environment-40594387">teleporting</a> people from starships to a planet’s surface anytime soon, we are getting closer to developing other tools essential for future space travel endeavours.</p>
<p>I am a lifelong Star Trek fan, but I am also a researcher that specializes in creating new magnetic materials. The field of <a href="https://www.physics.utoronto.ca/research/condensed-matter-physics">condensed-matter physics</a> encompasses all new solid and liquid phases of matter, and its study has led to nearly every technological advance of the last century, from computers to cellphones to solar cells.</p>
<p>My approach to looking for new phenomena in materials comes from a chemistry perspective: How can we create materials that have new properties that can change our world, and eventually be used to explore “strange, new worlds”? I believe an understanding of so-called “quantum materials” in particular is essential to make science-fiction science fact. </p>
<h2>Quantum materials</h2>
<p>What makes a substance a quantum material? Quantum materials have unusual and fantastic properties that arise from enormous numbers of particles acting in a concerted way.</p>
<p>Think of a conductor directing a symphony: without some order brought to the music, all you have is noise. The more musicians you have performing out of step, the more noise you will have.</p>
<p>A quantum material has all of the constituent musicians — in this case, the electrons or atoms in a material, which amounts to billions upon billions of particles — acting in a certain way according to quantum rules, or the “sheet music,” if you will.</p>
<p>Instead of noise from random electronic and atomic motions, with a conductor you get music — or in the case of new materials, a new property that emerges. The use of these new properties for devices is what is driving the technological revolutions that we are seeing today.</p>
<h2>Magnetic fields and shields</h2>
<p>So, how can these new materials be used in the spacecraft of tomorrow? One example might be the force-shields that protect ships in Star Trek. High magnetic fields could be used to protect bodies from incoming projectiles, especially if the projectiles have an electric charge.</p>
<p>How do you create large magnetic fields? One way is to use a superconducting magnet. Superconductors have electrons that conduct electricity with no resistance to flow. One of the consequences of this is that large magnetic fields can be generated — the current supported by a superconductor that generates the magnetic field can be huge without destroying the superconductivity itself.</p>
<p>These superconductors are used every day to create large magnetic fields in places such as hospitals for MRI (magnetic resonance imaging) devices to see inside the body.</p>
<p>Advanced superconductors might have new applications as magnetic shields for spacecraft. Imagine your spaceship coated in a superconductor that can generate a large magnetic field with a flick of a switch to get the current flowing, creating a magnetic force shield. </p>
<p>This is exactly what scientists at the European Organization for Nuclear Research, <a href="http://home.cern/about/updates/2015/08/superconducting-shield-astronauts">CERN, are investigating</a>: a new <a href="http://www.popularmechanics.com/space/moon-mars/a16757/cern-spaceship-shields/">magnetic shield for spacecraft</a> — superconducting magnesium diboride, or MgB₂.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/y-0z6_yVSAw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Physicist and science writer Ian O'Neill discusses CERN’s plan to create a superconducting cosmic radiation shield for astronauts.</span></figcaption>
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<h2>Superconductors on spaceships</h2>
<p>A spaceship coated in superconducting magnets would generate a “magnetosphere” around the craft which could be used to deflect harmful projectiles. While we don’t have to worry about <a href="http://www.startrek.com/database_article/klingons">Klingon</a> torpedoes just yet, we do have to worry about harmful cosmic rays in outer space for future space travel.</p>
<p><a href="https://home.cern/about/physics/cosmic-rays-particles-outer-space">Cosmic rays</a>) are typically charged particles that can interfere with the electronics of a spacecraft, and more importantly, give astronauts a lethal dose of radiation during long space flights.</p>
<p>Protecting future spacecraft from these rays is crucially important for the future of any space program, including trips to Mars in the next few decades. And who knows, with the superconducting magnet shields you might be able to escape a <a href="http://www.startrek.com/database_article/romulans">Romulan</a> attack on the way.</p>
<h2>Technical hurdles</h2>
<p>There is a catch, however. Superconductors do not work at high temperatures and there is no room-temperature superconductor. Above a certain temperature called the “critical temperature,” the superconductor becomes “normal” and the electrons experience a resistance to flow again. For magnesium diboride, this occurs at a very cold temperature — around -248°C. This is actually fine for interstellar space where the background temperature is a much colder -270°C or so but it is not conducive to spacecraft visiting other warmer planets.</p>
<p>Scientists like me are searching for “room temperature” superconductors that would enable these shields to work at much higher temperatures. This would also enable new advances to society such as cheaper health care, for example, since one wouldn’t need low temperatures for MRI instruments to work.</p>
<p>However, high temperature superconductivity has been a mystery for decades, and progress is in slow increments. As someone who works on the border between physics and chemistry, I believe that the answer will be found in the discovery of new materials. Historically, this is where progress has been made to raise the critical temperature to one above the liquid nitrogen boiling point of -196°C.</p>
<p>These superconductors would be great to use as magnetic shield devices if you were exploring many areas of the galaxy. But they wouldn’t work on warmer planets such as Mars without significant amounts of cryogens to keep the magnets cold.</p>
<h2>Quantum computers and societal revolution</h2>
<p>Superconducting technology would also have a variety of other uses aboard starships. <a href="https://uwaterloo.ca/institute-for-quantum-computing/quantum-computing-101">Quantum computers</a> can perform operations orders of magnitude faster than conventional computers, and would undoubtedly be used on a modern starship. Need to send an encrypted message to Starfleet? If the Klingons have a quantum computer, they might be able to intercept and hack your message, so you had better make sure that you understand the technology.</p>
<p>And superconducting electrical systems would naturally be used for the most efficient devices, from starship engines down to tricorders used in away missions. The emergence of room temperature superconductors would spark a transformation of our society that would rival the silicon age of modern electronics. Their discovery is an essential hurdle to cross for the next part of our evolution as a species to a new technological age.</p>
<p>It would be highly logical to continue our search for a room temperature superconductor. If only we could make it so. Quantum materials offer strange new worlds of discovery and perhaps most exciting are the technologies we haven’t discovered yet — that will exploit quantum effects on scale that humans can easily see.</p><img src="https://counter.theconversation.com/content/86378/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Wiebe receives funding from the Natural Science and Engineering Research Council of Canada (NSERC), the Canadian Foundation for Innovation (CFI), the Canada Research Chairs Program (CRC), and the Canadian Institute for Advanced Research (CIFAR).</span></em></p>Advanced materials that seem like they come from Star Trek are becoming reality today.Christopher Wiebe, Professor and Canada Research Chair in Quantum Materials Discovery, University of WinnipegLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/834552017-09-12T04:46:37Z2017-09-12T04:46:37ZHow the sky can help make air conditioners at least 20% more efficient<figure><img src="https://images.theconversation.com/files/185591/original/file-20170912-15801-179ywso.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Could the new invention spell the end of rooftop fans?</span> <span class="attribution"><span class="source">Christophe Finot/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Specially designed fluid-filled roof panels can help make air conditioning significantly more efficient, according to <a href="https://www.nature.com/articles/nenergy2017143">new research</a>.</p>
<p>These panels work like solar water heaters, except that they extract heat from the flowing fluid, rather than adding it. This has only been made possible through the development of new, highly reflective materials that allow more heat to be taken out of the fluid than finds its way back in, even in the heat of a sunny day.</p>
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Read more:
<a href="https://theconversation.com/how-to-keep-your-house-cool-in-a-heatwave-21991">How to keep your house cool in a heatwave</a>
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<p>As a result, the researchers, led by Eli Goldstein of Stanford University, calculate that these panels, when integrated into an existing air conditioning system, can use 20-50% less power to deliver the same amount of indoor cooling. This in turn could help smooth out demand peaks on the electricity grid in summer, cut energy bills, and reduce the risk of blackouts.</p>
<h2>Cool research</h2>
<p>For several years, the Stanford researchers and my own group at UTS in Sydney have been <a href="https://www.nature.com/articles/nenergy2017142">trying to design smart roof materials</a> that will help dissipate heat from air conditioning systems more effectively.</p>
<p>Conventional air-conditioning systems get rid of their heat by simply venting hot air from the system’s outdoor fan unit. But the new design adds an extra step, using a heat exchanger to pass the normal refrigerant heat into the fluid, which can be either water or glycol. This fluid then flows into the rooftop cooling panels so the heat can be dissipated into the sky. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185590/original/file-20170912-3875-1ot1ggj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185590/original/file-20170912-3875-1ot1ggj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185590/original/file-20170912-3875-1ot1ggj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=196&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185590/original/file-20170912-3875-1ot1ggj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=196&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185590/original/file-20170912-3875-1ot1ggj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=196&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185590/original/file-20170912-3875-1ot1ggj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=247&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185590/original/file-20170912-3875-1ot1ggj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=247&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185590/original/file-20170912-3875-1ot1ggj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=247&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The old system and the new.</span>
<span class="attribution"><span class="source">Goldstein et al. Nature Energy</span></span>
</figcaption>
</figure>
<p>The previous problem with this approach was that on hot, sunny days – when you need air conditioning the most – the Sun makes the fluid-filled panels heat up, rather than cool down.</p>
<p>This problem has only been solved in the past three years, with the design of super-reflective surfaces that can repel 97% of the incoming solar energy. </p>
<h2>Feeling the heat</h2>
<p>Nearly all synthetic and natural surfaces absorb at least 5% of incident solar heat. Even the best white roof paints typically absorb more than 10% of the Sun’s heat. The best-performing surface is a shiny, flawless layer of silver, but that doesn’t last very long in outdoor conditions. </p>
<p>But what if we can protect the silver, and maybe even improve its reflective performance by placing it under a layer that also helps to reflect solar energy? Three research groups came up with possible solutions, two involving <a href="http://onlinelibrary.wiley.com/doi/10.1002/advs.201500119/abstract">plastic</a> <a href="https://www.nature.com/nature/journal/v515/n7528/full/nature13883.html">coverings</a> for the silver, and the third involving a <a href="http://science.sciencemag.org/content/early/2017/02/08/science.aai7899">complex layering of different oxide materials</a>. </p>
<p>At UTS, our approach involved using many layers of two different plastics, placed on top of the silver. The resulting material reflects 97% of the incident solar energy, repelling the sun’s heat so effectively that the fluid inside <a href="http://onlinelibrary.wiley.com/doi/10.1002/advs.201500119/abstract">cools down</a>, even on a hot day.</p>
<h2>Look to the skies</h2>
<p>As the new Stanford research confirms, these super-reflective surfaces can perform a neat trick: getting the rooftop to lose heat during the day in the same way it does on a clear night. On clear nights, upward-facing surfaces can drop to several degrees below the ambient temperature because their heat dissipates high into the sky. The new super-cool roof panels do the same in the daytime as well. For example, they can condense dew well after sunrise even though the outdoor air temperature is above the dew point.</p>
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Read more:
<a href="https://theconversation.com/air-conditioning-we-need-to-talk-about-indoor-climate-change-11286">Air conditioning: we need to talk about indoor climate change</a>
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<p>The panels can easily be retrofitted onto existing air-conditioning systems, ultimately saving money in the long run because of the reduced energy use. By modelling their system’s performance, the Stanford researchers <a href="https://www.nature.com/articles/nenergy2017143">calculate</a> that the panels could reduce air-conditioning costs by 21% for a typical two-storey building in the sunny climate of Las Vegas.</p>
<p>These kind of hybrid systems could become commonplace, combining existing indoor air-conditioning technology with the new panels shedding the heat directly upwards into the sky. If you’ll pardon the pun, things are really looking up for those aiming to bring their energy bills down.</p><img src="https://counter.theconversation.com/content/83455/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Geoff Smith receives funding from Australian Research Council. </span></em></p>The invention of silver and plastic-clad roof panels that can cool themselves down even under the Sun’s full glare promise to make air conditioning much more energy-efficient.Geoff Smith, Emeritus Professor in Applied Physics, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/798792017-06-23T15:40:51Z2017-06-23T15:40:51ZNew form of carbon discovered that is harder than diamond but flexible as rubber<figure><img src="https://images.theconversation.com/files/175361/original/file-20170623-27875-1f5opco.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Timothy Strobel</span></span></figcaption></figure><p>Scientists have found a way to make carbon both <a href="http://advances.sciencemag.org/content/3/6/e1603213.full">very hard and very stretchy</a> by heating it under high pressure. This “compressed glassy carbon”, developed by researchers in China and the US, is also lightweight and could potentially be made in very large quantities. This means it might be a good fit for several sorts of applications, from bulletproof vests to new kinds of electronic devices.</p>
<p>Carbon is a special element because of the way its atoms can form different types of bonds with each other and so form different structures. For example, carbon atoms joined entirely by “sp³” bonds produce diamond, and those joined entirely by “sp²” bonds produce graphite, which can also be separated into single layers of atoms <a href="http://www.graphene.manchester.ac.uk/explore/what-can-graphene-do/">known as graphene</a>. Another form of carbon, known as glassy carbon, is also made from sp² and has properties of both graphite and ceramics.</p>
<p>But the new compressed glassy carbon has a mix of sp³ and sp² bonds, which is what gives it its unusual properties. To make atomic bonds you need some additional energy. When the researchers squeezed several sheets of graphene together at high temperatures, they found certain carbon atoms were exactly in the right position to form sp³ bonds between the layers.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/175363/original/file-20170623-27888-10qf2mj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/175363/original/file-20170623-27888-10qf2mj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/175363/original/file-20170623-27888-10qf2mj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/175363/original/file-20170623-27888-10qf2mj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/175363/original/file-20170623-27888-10qf2mj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/175363/original/file-20170623-27888-10qf2mj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/175363/original/file-20170623-27888-10qf2mj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Bond, sp³ bond.</span>
<span class="attribution"><span class="source">Timothy Strobel</span></span>
</figcaption>
</figure>
<p>By studying the new material in detail, they found that just over one in five of all its bonds were sp³. This means that most of the atoms are still arranged in a graphene-like structure, but the new bonds make it look more like a large, interconnected network and give it greater strength. Over the small scale of individual graphene sheets, the atoms are arranged in an orderly, hexagonal pattern. But on a larger scale, the sheets are arranged in a disorderly fashion. This is probably what gives it the combined properties of hardness and flexibility.</p>
<p>The researchers made the compressed glassy carbon using a relatively simple method that could be reproduced on a large scale easily and cheaply. In simple terms, they used a sort of machine press that applies high-pressure loads to the carbon. But this must have involved several tricks to control the pressure and temperature in exactly the right way. This would have been a time-consuming process but should still be achievable for other people replicate the results. </p>
<h2>New surprises</h2>
<p>Carbon materials are continually surprising us – and the emphasis of research has been to find or cook things in between its natural forms of diamond and graphite. This new form is the latest of what seem like limitless ways you can bond carbon atoms, following on from the <a href="http://science.sciencemag.org/content/306/5696/666">discovery of graphene</a>, <a href="http://nanotube.msu.edu/HSS/2006/1/2006-1.pdf">cylindrical carbon nanotubes</a> and <a href="http://www.nature.com/nature/journal/v318/n6042/abs/318162a0.html">spherical buckminsterfullerene molecules</a>.</p>
<p>A material like this – that is strong, hard, lightweight and flexible – will be in high demand and could be used for all sorts of applications. For example, military uses could involve shields for jets and helicopters. In electronics, lightweight, cheaply manufactured materials with similar properties to silicon that could also have new abilities could provide a way to overcome the limitations of existing microchips.</p>
<p>The dream is to find a carbon material that could replace silicon altogether. What is needed is something that allows electrons to move through it quickly and whose electrons can easily be placed into an excited state to represent the on and off functions of a transistor. The researchers behind glassy carbon haven’t studied these properties in the new material so we don’t yet know how suitable it might be. But it might not be that long until another of carbon is found. So far, decades of hunting hasn’t turned up what we need, but maybe we just have to look deep down to find it.</p><img src="https://counter.theconversation.com/content/79879/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elton Santos acknowledges the use of computational resources from the UK national high performance computing service, ARCHER, for which access was obtained via the UKCP consortium and funded by EPSRC grant ref EP/K013564/1; and the Extreme Science and Engineering Discovery Environment (XSEDE), supported by NSF grants number TG-DMR120049 and TG-DMR150017. The Queen’s Fellow Award through the startup grant number M8407MPH and the Energy Sustainable PRP (QUB) are also acknowledged.</span></em></p>Compressed glassy carbon could be used to make better bulletproof vests or new types of electronics.Elton Santos, Research Fellow, School of Mathematics and Physics, Queen's University BelfastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/708722017-01-19T15:07:11Z2017-01-19T15:07:11ZWe’ve created a new vibration-proof ‘metamaterial’ that could save premature babies’ lives<figure><img src="https://images.theconversation.com/files/153244/original/image-20170118-3927-i87vz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>There are <a href="http://www.bliss.org.uk/neonataltransport">16,000 transfers</a> of premature babies to medical facilities each year in the UK alone. The babies are often transported over large distances from rural to city locations over significant periods of time, in some cases two hours or more. The ambulances, helicopters or aircraft used are miniaturised intensive care units, containing all the equipment required to keep the baby alive.</p>
<p>But mechanical vibrations and noise from the equipment and transfer vehicle can provide significant, even life-threatening stress to the most vulnerable and delicate human lives. As we discovered when speaking to clinicians, transfers are sometimes aborted as a result of the stress that develops in the baby. These vehicles need materials and structures to reduce the noise and vibrations to tolerable levels.</p>
<p>Our team has recently developed a special “metamaterial” inspired by a nuclear reactor design that offers a double whammy of protection by combining two unusual properties known to dampen vibrations to a much greater degree than existing materials. Once we’ve tested and adapted the material, it could be used to help make safer neonatal transfer vehicles. And it could even be used in much bigger structures, for example to help prevent earthquake damage in buildings.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/153418/original/image-20170119-26585-16vjl03.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/153418/original/image-20170119-26585-16vjl03.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=658&fit=crop&dpr=1 600w, https://images.theconversation.com/files/153418/original/image-20170119-26585-16vjl03.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=658&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/153418/original/image-20170119-26585-16vjl03.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=658&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/153418/original/image-20170119-26585-16vjl03.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=826&fit=crop&dpr=1 754w, https://images.theconversation.com/files/153418/original/image-20170119-26585-16vjl03.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=826&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/153418/original/image-20170119-26585-16vjl03.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=826&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">How it works.</span>
<span class="attribution"><span class="source">Andy Alderson/Sheffield Hallam University</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p><a href="http://www.azom.com/article.aspx?ArticleID=11450">Auxetic materials</a> <a href="http://www.bbc.co.uk/programmes/p02jfq9q">can dampen vibrations</a>. They have what’s called a negative Poisson’s ratio, which means that they become thicker when stretched along their length, unlike an elastic band, which becomes thinner. Imagine stretching a crumpled or folded sheet of paper. The unfolding of the paper as it is stretched causes the sheet to become both longer and wider. This is the auxetic effect. </p>
<p>There are also other unusual materials that contract (rather than stretch) along their length when pulled lengthwise (<a href="http://silver.neep.wisc.edu/%7Elakes/NegStfPRL.pdf">negative stiffness</a>), which also have dramatic vibration damping properties when used as part of a composite material.</p>
<p>If you stand a ruler on its end and push it down from the top it will bend into a C shape. If you then push sideways against the mid-point of the outer edge of the C, initially the ruler will offer resistance to the sideways push. That’s positive stiffness. But keep increasing the force and the bend in the ruler snaps through to the other side, creating an inverted C shape. During the snap-through period, the ruler is working with the force, not resisting it. So in this transition phase it displays what is called negative stiffness.</p>
<p>One way of achieving such unusual properties is to develop mechanical metamaterials. These are made from a particular geometric arrangement of smaller building blocks that give the materials their <a href="http://iopscience.iop.org/article/10.1088/0034-4885/76/12/126501/meta">special mechanical properties</a>. We have developed “double negative” mechanical metamaterials that combine both negative Poisson’s ratio and negative stiffness properties simultaneously.</p>
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</figure>
<p><a href="http://onlinelibrary.wiley.com/doi/10.1002/adma.201603959/abstract;jsessionid=5827525BB34384F0035422891D1D9C39.f04t01">Our metamaterials</a> comprise interlocking hexagon building blocks that move together in all directions when compressed, by sliding along the interlocks that connect adjacent hexagons. This creates an auxetic effect.</p>
<p>These were in part inspired by the graphite core interlocking structures of some nuclear reactors designed and built in the 1950s and 1960s, which are auxetic and were specifically designed to withstand seismic vibrations during earthquakes. We have also added three negative stiffness elements – foam inserts, buckled beam inserts and an arrangement of magnets – between the interlocking blocks.</p>
<h2>Stopping bad vibes</h2>
<p>We expect the combination of both auxetic and negative stiffness properties in the bulk metamaterial will give it better vibration damping ability than if it just had one of these properties. And through careful design, we expect it to be able to dampen vibrations at many different frequencies.</p>
<p>Because the technology can be scaled up or down – and once we have determined exactly how good it is at dampening vibrations – it could be used in lots of different applications, from ambulances to buildings.</p>
<p>We also think the principle of combining these two properties could be used in other materials. For example, you could use collapsible auxetic truss structures as <a href="http://www.google.com/patents/US20130322955">rapidly deployable tents and shelters</a> in military and disaster-relief situations. Building negative stiffness into such structures would enable them to provide protection from severe vibrations, such as earthquakes.</p>
<p>We still need to turn the prototype technology into designed and manufactured products, but this metamaterial could have a vibrant future ahead of it.</p><img src="https://counter.theconversation.com/content/70872/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andy Alderson received support for preliminary work leading to the eventual double negative mechanical metamaterial concept in a collaboration with The University of Texas at Austin, funded by the US Army Research Office.</span></em></p><p class="fine-print"><em><span>Fabrizio Scarpa does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>This special dampening material could also protect buildings from earthquakes.Andy Alderson, Professor of Smart Materials and Structures, Sheffield Hallam UniversityFabrizio Scarpa, Professor of Smart Materials & Structures, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/700242016-12-14T15:09:09Z2016-12-14T15:09:09ZContact lens material could produce electric cars that recharge in minutes<figure><img src="https://images.theconversation.com/files/150148/original/image-20161214-2517-1ctr0jn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Running out of battery has become an all-too regular occurrence for most people with a smartphone. So imagine if you could recharge it in seconds. Or if you could recharge an electric car in the same time it takes to fill up a petrol vehicle. It would probably make owning one much more attractive. Well, my colleagues and I have developed a new material based on soft contact lenses that could make this a reality by making traditional batteries a thing of the past.</p>
<p>Instead of developing a battery, we’ve been working on a device called a supercapacitor that can charge and discharge its energy much more quickly. Supercapacitors are already used in lots of applications, <a href="https://cleantechnica.com/2015/11/26/electric-bus-adoption-taking-off-china/">even in some electric buses in China</a>. The problem with supercapacitors is that they don’t store much energy, so need to be recharged frequently. So the Chinese bus has to make a lot of stops.</p>
<p>Working with Ian Hamerton of Bristol University and Augmented Optics, <a href="http://pubs.acs.org/doi/abs/10.1021/ma5002436">we developed a material</a> that is far more efficient than those used in traditional supercapacitors. The technology hasn’t yet been developed into a working device but, if futher work proves successful, there would be lots of applications across transport, aerospace and energy generation, as well as household applications such as mobile phones, laptops and flat-screen electronic devices.</p>
<p><a href="http://engineering.mit.edu/ask/how-does-battery-work">Batteries store energy</a> through chemical reactions that alter the material making up the battery by moving around charged particles known as ions. It takes time to produce and separate these ions, which is why batteries are slow to charge and discharge. The most common battery in use at the moment, the lithium battery, uses ions of lithium to store the charge. Lithium is a <a href="http://fortune.com/2016/06/06/lithium-price-tesla-metal-future/">rare and expensive element</a> and there have been <a href="https://theconversation.com/why-batteries-have-started-catching-fire-so-often-68602">recent prominent cases</a> of lithium ion batteries catching fire.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/150151/original/image-20161214-2490-1gw58ua.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/150151/original/image-20161214-2490-1gw58ua.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/150151/original/image-20161214-2490-1gw58ua.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/150151/original/image-20161214-2490-1gw58ua.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/150151/original/image-20161214-2490-1gw58ua.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/150151/original/image-20161214-2490-1gw58ua.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/150151/original/image-20161214-2490-1gw58ua.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">No more waiting.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Supercapacitors, on the other hand, charge and discharge rapidly because there is no chemical change. Instead they involves a change in a magnetic property of the material’s atoms known as polarisation. While supercapacitors typically store just one tenth <a href="http://berc.berkeley.edu/storage-wars-batteries-vs-supercapacitors/">of the energy a battery does</a>, our new material can store between 1,000 and 10,000 times more energy for its size than conventional materials. This means they can store even more energy than lithium batteries.</p>
<p>Like a battery, a supercapacitor is basically made from two electrodes that hold the charge with a filling of some material. Research on improving supercapacitors has so far mainly concentrated on improving the electrodes by making <a href="http://pubs.rsc.org/en/content/articlelanding/2010/jm/b918672g#!divAbstract">nanostructured carbon materials</a> that have lots of tiny filaments. This vastly increases the surface area of the electrode compared to a flat material – but also adds to the expense. Instead, we have concentrated on improving the filling, making materials that are also supercapacitive.</p>
<h2>Swell material</h2>
<p>The materials in question are based on those used for soft contact lenses, which are flexible, transparent and take up water, and were <a href="https://www.google.com/patents/US4900764">first developed</a> 40 years ago by <a href="http://www.checkdirector.co.uk/director/donald-highgate/#director_1754002">Donald Highgate</a>. These materials are sometimes called gels but this isn’t really accurate because they can’t dissolve like gels. They are actually chains of plastic molecules that are chemically bonded together to form a cross-linked network. The network is loose so it allows water to enter and swell the material, but they don’t conduct electricity.</p>
<p>We were able to combine these materials with a conducting polymer, which by itself is fragile, dark coloured and insoluble in water. The combined material is flexible, conducts electricity and can take up water, which is important because it will stop the material catching fire.</p>
<p>We’re now hoping to work with a company called Supercapacitor Materials to build a working demonstrator by optimising how we manufacture the material. We then want to get the supercapacitor into electric cars, first alongside batteries to increase how long the vehicles can go with out recharging, but eventually as a replacement. This would make charging your electric car far easier than charging your phone is right now.</p><img src="https://counter.theconversation.com/content/70024/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brendan Howlin receives funding from research councils, government agencies and industry, including Augmented Optics Ltd.</span></em></p>Plan to develop long-lasting supercapacitors would provide a faster, safer alternative to lithium batteries.Brendan Howlin, Senior Lecturer, University of SurreyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/665322016-10-05T14:56:02Z2016-10-05T14:56:02ZThe Nobel Prize for Physics goes to topology – and mathematicians applaud<figure><img src="https://images.theconversation.com/files/140538/original/image-20161005-14232-9tfp4b.jpg?ixlib=rb-1.1.0&rect=176%2C131%2C923%2C708&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Math doesn't get its own Nobel, but is the foundation for much Prize-winning research.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/tereneta/88098709">Tim Ereneta</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p><a href="https://sharepoint.washington.edu/phys/people/Pages/view-person.aspx?pid=85">David Thouless</a>, <a href="http://physics.princeton.edu/%7Ehaldane/">Duncan Haldane</a> and <a href="https://vivo.brown.edu/display/jkosterl">Michael Kosterlitz</a> received the <a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/2016/">2016 Nobel Prize for Physics</a> for their work on exotic states of matter. They were inspired by the observation that some materials have unusual electrical properties – and their investigations led them to topology. That’s the branch of mathematics concerned with the properties of geometric objects that don’t change when bent or stretched (though torn would be a different story). As there is no Nobel Prize for mathematics, the topology community is understandably excited by this recognition of the utility of our discipline.</p>
<p>The old saw is that a topologist is a mathematician who cannot tell the difference between a doughnut and a coffee cup. (This joke is getting tiresome, but we stick with it anyway.) Both objects have just one hole and it’s easy to see how to deform one to the other.</p>
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<figcaption><span class="caption">Mmm…doughnut. (Video by Jim Fowler)</span></figcaption>
</figure>
<p>Topology aims to classify these spaces via indirect means. Since it’s often rather difficult to demonstrate how to deform a particular space to make it look like another, topologists develop mathematical machinery that takes spaces as an input and produces an algebraic object. This output might just be a number or it could be more complicated, but the machine should take spaces that are “the same” and spit out the same result. This allows us to distinguish spaces – two inputs are different if the corresponding outputs are different.</p>
<p>For example, it may seem obvious that a doughnut and a sphere are distinct objects, but just because you cannot see how to deform one to the other it doesn’t follow that it’s impossible. Topology comes to the rescue, however. One of many ways to show that a sphere and a doughnut aren’t the same is to compute their <a href="https://en.wikipedia.org/wiki/Fundamental_group">fundamental groups</a>. This is an algebraic object built from considering loops in the space.</p>
<p>A useful way to visualize loops is to imagine a rubber band lying on the surface of an object. First consider the sphere. Any loop on the sphere contains a disc inside it, and now you can imagine shrinking that loop down to a single point by pulling it through the disc. So there aren’t any interesting loops on the sphere – they are all deformable to a single point.</p>
<p>That’s not true for the doughnut, however. In fact there are lots of interesting loops on its surface (we are dealing with a hollow doughnut; there’s nothing but air inside). One such loop is obtained by drawing a circle around a vertical cross section (the blue loop in the figure below). Another arises from a horizontal cross-section (the red loop). It’s impossible to contract these loops down to a the same single point, so the fundamental groups of the sphere and doughnut aren’t the same and thus, they are different objects.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/140350/original/image-20161004-20223-148ey14.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/140350/original/image-20161004-20223-148ey14.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/140350/original/image-20161004-20223-148ey14.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=334&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140350/original/image-20161004-20223-148ey14.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=334&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140350/original/image-20161004-20223-148ey14.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=334&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140350/original/image-20161004-20223-148ey14.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=419&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140350/original/image-20161004-20223-148ey14.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=419&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140350/original/image-20161004-20223-148ey14.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=419&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Loops on a doughnut.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:ToricCodeTorus.png">Woottonjames</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>The topology of materials</h2>
<p>Topology works in all dimensions, but physics is mostly concerned with our three-dimensional universe (well, that’s not always true – just ask <a href="https://en.wikipedia.org/wiki/String_theory#Extra_dimensions">string theorists</a>). When studying electrical properties of materials, we are definitely dealing with three dimensions. Even a thin wire has length, width and height. For a fixed electrical conductor, say a copper wire, it’s usually possible to determine the relationship between the voltage placed on the wire and the current that flows. Sometimes, however, materials experience an electrical phase transition (<a href="https://en.wikipedia.org/wiki/Superconductivity#Superconducting_phase_transition">superconductivity</a>, for example, which is obtained by lowering the temperature of the material) and the usual equations governing voltage and current break down. </p>
<p>Thouless, Haldane and Kosterlitz discovered that mathematically these <a href="https://en.wikipedia.org/wiki/Kosterlitz%E2%80%93Thouless_transition">transitions</a> correspond to an abrupt change in the topological type of the material. Certain thin films can be considered as being two-dimensional – imagine a surface that’s only one atom thick – and electrical current often flows in channels on the surface with low resistance. It turns out that there are points where the electrons flow around in a circular motion, sometimes clockwise and sometimes counterclockwise, and the number of such points can change as the material undergoes a phase transition.</p>
<p>Mathematicians immediately recognize this type of space from a first course in algebraic topology – it’s a plane with a few points removed and its fundamental group is very easy to compute. It turns out that the number of these types of points completely determines the topological type of the space.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/140526/original/image-20161005-14246-30gs8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/140526/original/image-20161005-14246-30gs8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/140526/original/image-20161005-14246-30gs8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140526/original/image-20161005-14246-30gs8d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140526/original/image-20161005-14246-30gs8d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140526/original/image-20161005-14246-30gs8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140526/original/image-20161005-14246-30gs8d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140526/original/image-20161005-14246-30gs8d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How can you scientifically describe a black hole without math?</span>
<span class="attribution"><a class="source" href="http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA16695">NASA/JPL-Caltech</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Topology elsewhere in physics</h2>
<p>Einstein’s <a href="https://en.wikipedia.org/wiki/General_relativity">general theory of relativity</a> posits that space-time is curved by gravity. The equations also imply the existence of black holes, which in mathematical terms correspond to <a href="https://en.wikipedia.org/wiki/Singularity_theory">singularities</a>, points in a space where all hell breaks loose (so to speak). A typical example familiar to calculus students is a point on the graph of a function where the derivative fails to exist. Much more complicated examples are possible and the space around such points can have interesting topology. Around ordinary points, space looks like a three-dimensional ball, but around singularities space can be knotted in unusual ways. Of course, we can’t experience this ourselves, but we can model it mathematically.</p>
<p>Topology has provided a framework in physics in other ways, such as the development of <a href="https://en.wikipedia.org/wiki/Topological_quantum_field_theory">topological quantum field theories</a>. <a href="https://en.wikipedia.org/wiki/String_theory">String theory</a> is a generalization of this idea in which particles are modeled by one-dimensional objects called strings. These theories, unlike Einstein’s four-dimensional spacetime, require extra dimensions to be consistent – either 10, 11 or 26 depending on which model you prefer. Why don’t we observe these dimensions? The prevailing interpretation is that they are “small” and curl up on themselves so that we don’t notice. These extra dimensions form a type of space familiar to algebraic geometers called a <a href="https://en.wikipedia.org/wiki/Calabi%E2%80%93Yau_manifold">Calabi-Yau manifold</a>. </p>
<p>So it seems that a great deal of theoretical physics is based in sophisticated mathematics. Using ideas from topology, algebraic geometry and abstract algebra, not to mention differential equations and probability, physicists attempt to make sense of our universe. While math may not have its own Nobel Prize, many of the significant advances in other disciplines would not be possible without the development of sophisticated mathematics to provide the proper language for stating the results (Heisenberg’s <a href="https://en.wikipedia.org/wiki/Uncertainty_principle">uncertainty principle</a>, for example).</p>
<p>This is all heady stuff. In the end, though, the discoveries made by Thouless, Haldane and Kosterlitz have led to practical devices currently in use in industry (for example, efficient hard drives in computers) and may lead to advances in <a href="https://en.wikipedia.org/wiki/Quantum_computing">quantum computing</a>. Understanding how electrons move in materials is crucial to building better computers and instruments, and it’s exciting for us mathematicians to know that topology can help get us there.</p><img src="https://counter.theconversation.com/content/66532/count.gif" alt="The Conversation" width="1" height="1" />
There’s no Nobel Prize in mathematics, but math undergirds much high-level science. The 2016 Nobel in Physics rewards work in topology, a branch of math with multiple real world applications.Kevin Knudson, Professor of Mathematics, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/585632016-06-15T09:48:02Z2016-06-15T09:48:02ZGraphene isn’t the only Lego in the materials-science toy box<figure><img src="https://images.theconversation.com/files/125607/original/image-20160607-15061-z3xkka.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Materials science has lots of options for building.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/dolske/5261409077/">dolske/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>You may have heard of graphene, a sheet of pure carbon, one atom thick, that’s all the rage in materials-science circles, and getting plenty of media hype as well. Reports have trumpeted graphene as an <a href="http://www.futuristspeaker.com/business-trends/extreme-graphene-and-the-coming-super-materials-gold-rush/">ultra-thin, super-strong</a>, <a href="http://www.techtimes.com/articles/107648/20151117/why-graphene-miracle-material.htm">super-conductive</a>, super-flexible material. You could be excused for thinking it might even <a href="http://www.cnn.com/2013/10/02/tech/innovation/graphene-quest-for-first-ever-2d-material/">save all of humanity</a> from certain doom.</p>
<p>Not exactly. In the current world of nano-electronics, there is a lot more going on than just graphene. One of the materials I work with, molybdenum disulphide (MoS₂), is a one-layer material with interesting properties beyond those of graphene. MoS₂ can absorb <a href="http://www.nature.com/news/the-super-materials-that-could-trump-graphene-1.17775">five times</a> as much visible light as graphene, making it useful in light detectors and solar cells. In addition, even newer materials like borophene (a one-layer material made of boron atoms <a href="http://gizmodo.com/move-over-graphene-the-latest-super-material-is-borop-1748663333">projected to be mechanically stronger than graphene</a>) are being proposed and synthesized every day.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/122790/original/image-20160517-15926-gim2ud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/122790/original/image-20160517-15926-gim2ud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122790/original/image-20160517-15926-gim2ud.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122790/original/image-20160517-15926-gim2ud.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122790/original/image-20160517-15926-gim2ud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122790/original/image-20160517-15926-gim2ud.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122790/original/image-20160517-15926-gim2ud.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Layering two-dimensional materials.</span>
<span class="attribution"><span class="source">Peter Byrley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>These and other materials yet to be discovered will be used like <a href="http://www.nature.com/nature/journal/v499/n7459/abs/nature12385.html">Lego pieces</a> to build the electronics of the future. By stacking multiple materials in different ways, we can take advantage of different properties in each of them. The new electronics built with these combined structures will be faster, smaller, more environmentally resistant and cheaper than what we have now.</p>
<h2>Looking for an energy gap</h2>
<p>There is a key reason that graphene will not be the versatile cure-all material that the hype might suggest. You can’t just stack graphene repeatedly to get what you want. The electronic property preventing this is the lack of what is called an “<a href="http://news.mit.edu/2010/explained-bandgap-0723">energy gap</a>.” (The more technical term is “band gap.”)</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/126208/original/image-20160610-29238-1g7htbr.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/126208/original/image-20160610-29238-1g7htbr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=648&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126208/original/image-20160610-29238-1g7htbr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=648&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126208/original/image-20160610-29238-1g7htbr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=648&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126208/original/image-20160610-29238-1g7htbr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=815&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126208/original/image-20160610-29238-1g7htbr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=815&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126208/original/image-20160610-29238-1g7htbr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=815&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">What the energy gap looks like.</span>
<span class="attribution"><span class="source">Peter Byrley</span></span>
</figcaption>
</figure>
<p>Metals will conduct electricity through them regardless of the environment. However, any other material that is not a metal needs a little boost of energy from the outside to get electrons to move through the band gap and into the conducting state. How much of a boost the material needs is called the energy gap. The energy gap is one of the <a href="http://www.wiley.com/WileyCDA/WileyTitle/productCd-0471143235.html">factors that determines how much total energy</a> needs to be put into your entire electrical device, from either heat or applied electrical voltage, to get it to conduct electricity. You essentially have to put in enough starting energy if you want your device to work.</p>
<p>Some materials have a gap so large that almost no amount of energy can get electrons flowing through them. These materials are called <a href="http://www.nia.org/">insulators</a> (think glass). Other materials have either an extremely small gap or no gap at all. These materials are called <a href="http://www.dummies.com/how-to/content/electronics-basics-direct-and-alternating-current.html">metals</a> (think copper). This is why we use copper (a metal with instant conductivity) for wiring, while we use plastics (an insulator that blocks electricity) as the protective outer coating. </p>
<p>Everything else, with gaps in between these two extremes, is called a <a href="http://www.dummies.com/how-to/content/electronics-basics-what-is-a-semiconductor.html">semiconductor</a> (think silicon). Semiconductors, at the theoretical temperature of absolute zero, <a href="http://www.pveducation.org/pvcdrom/pn-junction/conduction-in-semiconductors">behave as insulators</a> because they have no heat energy to get their electrons into the conducting state. At room temperature, however, heat from the surrounding environment provides just enough energy to get some electrons (hence the term, “semi”-conducting) over the small band gap and into the conducting state ready to conduct electricity.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/126209/original/image-20160610-29222-1wkgxb1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/126209/original/image-20160610-29222-1wkgxb1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126209/original/image-20160610-29222-1wkgxb1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126209/original/image-20160610-29222-1wkgxb1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126209/original/image-20160610-29222-1wkgxb1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=557&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126209/original/image-20160610-29222-1wkgxb1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=557&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126209/original/image-20160610-29222-1wkgxb1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=557&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Comparing the band gap in metals (left), semiconductors (center) and insulators (right).</span>
<span class="attribution"><span class="source">Peter Byrley</span></span>
</figcaption>
</figure>
<h2>Graphene’s energy gap</h2>
<p>Graphene is in fact a <a href="http://electroiq.com/blog/2011/07/graphene-semimetal-not-semiconductor-insulator-or-metal/">semi-metal</a>. It has no energy gap, which means it will always conduct electricity – you can’t turn off its conductivity. </p>
<p>This is a problem because electronic devices use electrical current to communicate. At their most fundamental level, computers communicate by sending 1’s and 0’s – on and off signals. If a computer’s components were made from graphene, the system would <a href="http://www.geek.com/chips/graphene-transistors-cant-be-turned-off-wont-replace-silicon-in-processors-1308056/">always be on, everywhere</a>. It would be unable to perform tasks because its lack of energy gap prevents graphene from ever becoming a zero; the computer would keep reading 1’s all the time. Semiconductors, by contrast, have an energy gap that is small enough to let some electrons conduct electricity but is <a href="http://www.rsc.org/chemistryworld/2015/09/graphene-band-gap-electronics-transistors-semiconductor">large enough to have a clear distinction between on and off states</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/125450/original/image-20160606-13091-19gke3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/125450/original/image-20160606-13091-19gke3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/125450/original/image-20160606-13091-19gke3b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/125450/original/image-20160606-13091-19gke3b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/125450/original/image-20160606-13091-19gke3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/125450/original/image-20160606-13091-19gke3b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/125450/original/image-20160606-13091-19gke3b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Imagining using a computer based on graphene.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-142158799/stock-photo-annoyed-designer-gesturing-in-front-of-her-laptop-in-her-office.html">Woman with computer via shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Finding the right materials</h2>
<p>Not all hope is lost, however. Researchers are looking at three main ways to tackle this:</p>
<ol>
<li>Using new materials similar to graphene that actually have a sufficient energy gap and finding ways to further improve their conductivity.</li>
<li>Altering graphene itself to create this energy gap.</li>
<li>Combining graphene with other materials to optimize their combined properties.</li>
</ol>
<p>There are many one-layer materials currently being looked at that actually have a sufficient energy gap. One such material, MoS₂, has been studied in recent years as a potential <a href="http://www.bbc.com/news/technology-16034693">replacement for traditional silicon</a> and also as a <a href="http://phys.org/news/2015-12-creativity-ultrafast-thin-photodetector.html">light detector</a> and <a href="http://dx.doi.org/10.1038/srep08052">gas sensor</a>.</p>
<p>The only drawback with these other materials is that so far, we have not found one that matches the <a href="http://www.newyorker.com/magazine/2014/12/22/material-question">excellent though always-on conductivity</a> of graphene. The other materials can be turned off, but when on, they are not as good as graphene. MoS₂ itself is estimated to have 1/15th to 1/10th the conductivity of graphene in small devices. Researchers, including me, are now looking at ways to alter these materials to increase their conductivity.</p>
<h2>Using graphene as an ingredient</h2>
<p>Strangely, an energy gap in graphene can actually be induced through modifications like <a href="http://dx.doi.org/10.1016/j.ssc.2015.10.020">bending it</a>, turning it into a <a href="http://dx.doi.org/10.1038/nnano.2014.307">nanoribbon</a>, <a href="http://dx.doi.org/10.1039/C2RA22664B">inserting foreign chemicals into it</a> or using <a href="https://www-als.lbl.gov/index.php/research-areas/spectroscopy/56-bilayer-graphene-gets-a-bandgap.html">two layers</a> of graphene. But each of these modifications can reduce the graphene’s conductivity or limit how it can be used.</p>
<p>To avoid specialized setups, we could just combine graphene with other materials. By doing this, we are also combining the properties of the materials in order to reap the best benefits. We could, for example, invent new electronic components that have a material allowing them to be shut off or on (like MoS₂) but have graphene’s great conductivity when turned on. New <a href="http://www.graphene-info.com/mits-graphene-and-molybdenum-disulfide-based-solar-cells-achieveultimate-power-conversion">solar cells</a> will work on this concept. </p>
<p>A combined structure could, for example, be a solar panel made for harsh environments: We could layer a thin, transparent protective material over the top of a very efficient solar-collecting material, which in turn could be on top of a material that is <a href="http://dx.doi.org/10.1021/nl401544y">excellent at conducting electricity</a> to a nearby battery. Other middle layers could include materials that are good at selectively detecting gases such as methane or carbon dioxide.</p>
<p>Researchers are now racing to figure out what the best combination is for different applications. Whoever finds the best combination will eventually win numerous rights to patents for improved electronic products.</p>
<p>The truth is, though, we don’t know what our future electronics will look like. New Lego pieces are being invented all the time; the ways we stack or rearrange them are changing constantly, too. All that’s certain is that the insides of electronic devices will look drastically different in the future than they do today.</p><img src="https://counter.theconversation.com/content/58563/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Byrley receives funding from U.S. Department of Education. </span></em></p>Molybdenum disulphide, hexagonal boron nitride and other materials yet to be discovered will be used to build the electronics of the future.Peter Byrley, Ph.D. Candidate in Chemical Engineering, University of California, RiversideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/445432016-01-25T17:00:10Z2016-01-25T17:00:10ZThe race to hypersonic speed: will air passengers feel the benefits?<figure><img src="https://images.theconversation.com/files/88544/original/image-20150715-26325-fo17wo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An impression of the X-51 Waverider, the US hypersonic aircraft programme.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:X-51A_Waverider.jpg">NASA</a></span></figcaption></figure><p>When Concorde entered service 40 years ago, it more than doubled the speed of air travel at a stroke. Following Concorde’s retirement, airliners today fly once more at subsonic speeds, but engineers worldwide are looking to a future in which high-speed flight is an everyday occurrence. Except they want to go one better: not at supersonic, but hypersonic speeds.</p>
<p>Aerospace giant Airbus was last year <a href="http://www.theguardian.com/business/2015/aug/05/airbus-patents-hypersonic-plane-paris-tokyo-three-hours">awarded a patent</a> that details how a future hypersonic aircraft, with delta wings reminiscent of Concorde, could travel at Mach 4.5 – fast enough to carry passengers between Paris and Tokyo in just three hours. </p>
<p>But inevitably, technology that has reached the commercial realm will already have been investigated by the military. The US, Russia and China have all carried out test flights of hypersonic vehicles – those which travel at around five times the speed of sound – with varying degrees of success. Each also has plans for weapons systems that could be developed from them.</p>
<p>Because while these are often referred to as “<a href="http://www.thetimes.co.uk/tto/technology/article4481252.ece">fighter jets</a>”, in truth the machines are more similar to missiles. Without pilots, they sit atop rockets which boost them to high supersonic speeds (Mach 4 and above), at which point they start up their own engines (if equipped) and accelerate to even faster cruise speeds - but not for long, as they usually run out of fuel quickly, and most of their flight time is spent in a glide, albeit an extremely fast one.</p>
<p>Current missiles have operated in this fashion for decades. Intercontinental ballistic missiles (ICBM) and some shorter-range versions use the same sort of flight path, with the missile formed of multiple rocket stages to provide enough power to arc high into the atmosphere, only flying faster and higher. The now retired US <a href="http://fas.org/man/dod-101/sys/missile/aim-54.htm">AIM-54 Phoenix air-to-air missile</a> had a top speed of Mach 5. What makes the current generation of hypersonic aircraft designs different is their capability to manoeuvre, making them harder to intercept.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/88543/original/image-20150715-26325-1kwmtmp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/88543/original/image-20150715-26325-1kwmtmp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/88543/original/image-20150715-26325-1kwmtmp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/88543/original/image-20150715-26325-1kwmtmp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/88543/original/image-20150715-26325-1kwmtmp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/88543/original/image-20150715-26325-1kwmtmp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/88543/original/image-20150715-26325-1kwmtmp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/88543/original/image-20150715-26325-1kwmtmp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">X-43 rocket plane dropped from a B-52, seconds before igniting its scramjet engines and reaching a world record-holding 10,000km/h (Mach 9.8).</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:B-52B_with_X43.jpg">NASA</a></span>
</figcaption>
</figure>
<h2>The need for speed</h2>
<p>Why bother? There are two main reasons for the fresh interest shown by the military in hypersonic aircraft. The first is that a very fast, highly manoeuvrable weapon is not easy to counter: it can be difficult to detect and its speed means that there is little time for defences to react, much less to actually take any action to stop it. This makes it a threat to supposedly heavily defended targets – and most discussion of the Chinese hypersonic craft, dubbed <a href="http://missilethreat.com/china-confirms-hypersonic-missile-test-2/">Wu-14</a>, and the Russian equivalent, the <a href="http://www.ibtimes.com/russias-secret-hypersonic-nuclear-missile-yu-71-can-breach-existing-missile-defense-1987590">Yu-71</a>, mention penetrating US missile defence systems as a primary aim.</p>
<p>The second relates to a requirement that has become more urgent in recent years, namely to shorten response time and to attack mobile targets. While drones, satellites and the like can locate them easily enough, highly mobile enemy units – anything from terrorist groups to Scud missile launchers – will not hang around waiting for the inevitable airstrike to be called in. A very fast weapons platform with the ability to manoeuvre means that once found, a target will have little time and less opportunity to escape.</p>
<h2>Material shortfall</h2>
<p>Of course, to create a workable hypersonic vehicle, engineers have to overcome, or at least cope with, the severe environment encountered by something moving that fast. The main problem (from which most if not all the others stem) is <em>heat</em> – heat from air friction and from the shock waves generated by moving faster than the speed of sound. </p>
<p>The temperatures a hypersonic vehicle encounters are so high that conventional materials can’t withstand them and maintain their strength. There are materials that can insulate a structure from the heat, but they tend not to be very strong in themselves, and so any breach of insulation can quickly lead to catastrophic failure – as demonstrated by the tragic <a href="http://www.bbc.com/future/story/20150130-what-caused-the-columbia-disaster">loss of the space shuttle Columbia</a> in 2003, and also of some <a href="http://www.thetimes.co.uk/tto/news/world/americas/article3122654.ece">current test vehicles</a>. Research into new heat-resistant materials and suitable manufacturing techniques is therefore a priority.</p>
<p>High air temperatures also reduce the thrust of an air-breathing jet engine, so new propulsion concepts are also needed – relying on rocket engines tends to lead to overly large and heavy aircraft. Among the companies leading the way on propulsion technology is British company Reaction Engines, which is testing the revolutionary <a href="http://www.reactionengines.co.uk/sabre_howworks.html">Sabre variable-cycle engine</a>.</p>
<p>Travelling at very high speeds will also require advanced sensors and controls. New materials will be needed again, as conventional radomes and antennae would never withstand the heat. Conformal antennae – where the craft’s fuselage skin is used as the transmitter and receiver – are a possibility, though this is not guaranteed to work. Depending on just how fast the vehicle is designed to travel, ionisation of the air around it could interfere with radio-frequency sensors and communications.</p>
<h2>Hypersonic flight for all?</h2>
<p>Whether it’s possible to create a crewed or passenger hypersonic aircraft is still up for debate. But producing any sort of hypersonic vehicle is a long-term project that will take a lot of time and effort – and a whole lot of money. Patents mark the ground as to where some may follow. But who out there has the will, the persistence and the funds to do so?</p><img src="https://counter.theconversation.com/content/44543/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Phillip Atcliffe does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The military is interested – but the rest of us could also get from Paris to Tokyo in three hours.Phillip Atcliffe, Senior Lecturer in Aeronautical Engineering, University of SalfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/460982015-11-04T13:06:56Z2015-11-04T13:06:56ZA new generation of weird-looking space suits will take us to Mars<figure><img src="https://images.theconversation.com/files/100628/original/image-20151103-16502-15pled7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">NASA</span></span></figcaption></figure><p>When Russian cosmonaut Alexei Leonov conducted the world’s first space walk in 1965, the mission nearly <a href="https://theconversation.com/the-first-space-walk-happened-50-years-ago-and-nearly-ended-in-disaster-38921">ended in catastrophe</a>. After 12 minutes outside the Voskhod spacecraft, the vacuum of space had caused Leonov’s suit to inflate so much he couldn’t get through the air lock. He was forced to manually vent oxygen from inside the suit to reduce its size and get back onto the ship before the effects of decompression sickness overcame him.</p>
<p>Amazingly, the design of many of the space suits in use today hasn’t changed that much. The Russians still use a variant of Leonov’s one-size-fits-all suit, the <a href="https://www.nasa.gov/externalflash/ISSRG/pdfs/orlan.pdf">Orlan M</a>, and the Chinese use the visibly <a href="http://www.spacesafetymagazine.com/aerospace-engineering/space-suit-design/space-wardrobe-design-chinese-spacesuit-analysis-inspiration/">similar Feitian</a>. And while NASA’s <a href="https://www.nasa.gov/pdf/188963main_Extravehicular_Mobility_Unit.pdf">Extravehicular Mobility Unit</a> (EMU) has been updated since its initial development in the 1980s, its primary life support system dates to the Apollo missions of the 1960s.</p>
<p>However, the advent of manned flights to Mars and advances in materials technology could change all this. For space tourism to take off and mankind to step on Mars, we need suits that may look very different to those used today. Engineers are now developing a new generation of space suits that could help astronauts withstand longer periods of time in space and deal with the hazards of exploring other planets.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/100629/original/image-20151103-16502-3ofjqr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/100629/original/image-20151103-16502-3ofjqr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/100629/original/image-20151103-16502-3ofjqr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/100629/original/image-20151103-16502-3ofjqr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/100629/original/image-20151103-16502-3ofjqr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/100629/original/image-20151103-16502-3ofjqr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/100629/original/image-20151103-16502-3ofjqr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Future template?</span>
<span class="attribution"><span class="source">20th Century Fox</span></span>
</figcaption>
</figure>
<h2>Mini spacecraft</h2>
<p>Most space suits are essentially mini spacecraft. Although typically just a few millimetres thick, the suits have to provide life support and protection against the vacuum, temperature extremes and micrometeorites of space. Without this protection, the drop in pressure <a href="http://www.scientificamerican.com/article/survival-in-space-unprotected-possible/">would cause</a> the body to swell up and lethal bubbles of nitrogen gas to form in the blood.</p>
<p>Suits that maintain a lower pressure, such as the 4.3 pounds per square inch (psi) of NASA’s EMU, make it much easier to move and so are less tiring. This makes a huge difference when spacewalks can last up to eight hours. The downside is this also increases the time an astronaut needs to spend breathing pure oxygen to reduce the risk of gas bubbles forming in the blood.</p>
<p>For its Mars suit, however, NASA is looking at much higher pressure designs such as the <a href="http://www.nasa.gov/content/nasa-s-next-prototype-spacesuit-has-a-brand-new-look-and-it-s-all-thanks-to-you">soft Z-2</a> and the hard-and-soft hybrid Mark III. These would effectively “dock” into the spacecraft or Mars base building, allowing the astronaut to enter but leaving the suits – and the irritating and potentially toxic Martian dust – outside.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_kL53wmKg9A?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>A completely different approach would be to replace suits that pressurise the gas around the body with tight-fitting, stretchy garments that provide mechanical counter-pressure. This idea was first proposed in the 1970s but has only recently become possible with the creation of suitable materials. One example is <a href="http://news.mit.edu/2014/second-skin-spacesuits-0918">the “BioSuit”</a> developed at the Massachussets Institute of Technology (MIT), which uses nickel-titanium shape-memory alloys to form a “second skin”.</p>
<p>Such a suit would also be much lighter than the 130kg of the EMU. It could also increase resilience, as minor rips or tears would be less likely to cause immediate fatal depressurisation. But this kind of suit will still need a space helmet to deliver breathable gas to the astronaut. Interestingly, the BioSuit <a href="http://www.bloomberg.com/news/articles/2015-01-08/spacex-space-suit-will-combine-function-with-design">is rumoured</a> to form the basis for the suit being developed by Elon Musk’s company <a href="http://www.spacex.com/">SpaceX</a> for its astronauts to wear inside its Dragon capsule.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/100626/original/image-20151103-16542-167lke0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/100626/original/image-20151103-16542-167lke0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/100626/original/image-20151103-16542-167lke0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/100626/original/image-20151103-16542-167lke0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/100626/original/image-20151103-16542-167lke0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/100626/original/image-20151103-16542-167lke0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/100626/original/image-20151103-16542-167lke0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In a spin: the SkinSuit.</span>
<span class="attribution"><span class="source">NASA–Waldie</span></span>
</figcaption>
</figure>
<h2>Under pressure</h2>
<p>Astronauts have always worn full-pressure suits during landing and takeoff and once they’re safely in space, for example on board the International Space Station, they can wear shorts and t-shirts. But since the 1970s, the Russians have recommended donning the <a href="https://books.google.co.uk/books?id=nuEYQB1ImPcC&pg=PA167&lpg=PA167&dq=russian+penguin+suit+research&source=bl&ots=YyoQbTwF0x&sig=pDhAl8wAo0OxT6AyPz-kXgkgN7g&hl=en&sa=X&ved=0CEoQ6AEwB2oVChMI46KKsZD0yAIVAQgaCh1_TwT3#v=onepage&q=russian%20penguin%20suit%20research&f=false">Pengvin (Penguin) suit</a> in an attempt to prevent the loss of muscle and bone and the spinal stretching that occur when astronauts spend a time in zero-gravity environments. This can <a href="http://www.scientificamerican.com/article/astronauts-get-taller-in-space/">increase their height</a> by as much as 7cm, preventing them from fitting into their space suits or moulded seats in the Soyuz transport vehicles that at the moment are the only way back to Earth.</p>
<p>The Pengvin suit comprises a belt with bungee cords wrapped around the shoulders and feet. This compresses the body in a way that loads it with the equivalent of 40kg of weight in order to simulate gravity. The problem is we do not experience gravity on Earth as a weight on our shoulders, and so astronauts usually choose not to wear the suit because it is very uncomfortable.</p>
<p>To overcome this, we have worked with the European Space Agency and international colleagues to create another <a href="http://blogs.esa.int/iriss/2015/08/12/revealing-the-identity-of-skinsuit-man">body-tight suit</a> that creates resistance at each point around the body that is proportional to that of real gravity. This means the full force of the combined “weight” is only felt at the feet, making the suit feel much more natural and comfortable to wear. Our research has shown that this “Gravity-Loading SkinSuit” can significantly reduce spine lengthening in a weightless environment, with a force less than 30% of Earth’s gravity.</p>
<p>ISS astronaut <a href="http://www.dailymail.co.uk/sciencetech/article-3272300/Astronaut-trials-gravity-mimicking-SkinSuit-ISS-generation-clothing-inspired-Olympics-prevent-backache-space.html">Andreas Mogensen</a> wore the SkinSuit during his mission to the International Space Station in September 2015 but we have yet to find out if he has found it tolerable and whether it reduced any back pain and spine lengthening. Ultimately though, we hope these suits will reduce the risk of back injury due to intervertebral disc prolapse (slipped disc) when the astronauts land – something that would be catastrophic for a mission to Mars.</p><img src="https://counter.theconversation.com/content/46098/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Andrew Green receives funding from the European Space Agency to develop a new kind of spacesuit.</span></em></p><p class="fine-print"><em><span>Matteo Stoppa does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New materials and new designs could help astronauts withstand longer periods of time in space and deal with the hazards of exploring other planets.David Andrew Green, Senior Lecturer of Human & Aerospace Physiology , King's College LondonMatteo Stoppa, PhD candidate in Electronic Devices, King's College LondonLicensed as Creative Commons – attribution, no derivatives.