tag:theconversation.com,2011:/id/topics/nature-communications-journal-10394/articlesNature Communications (journal) – The Conversation2016-10-06T16:54:53Ztag:theconversation.com,2011:article/666222016-10-06T16:54:53Z2016-10-06T16:54:53ZShape-shifting materials could be crucial in tight spaces – such as inside our bodies<figure><img src="https://images.theconversation.com/files/140738/original/image-20161006-14726-1uj9lcb.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">cybrain/shutterstock.com</span></span></figcaption></figure><p>The rise of 3D printing means it’s now easy to create objects to any design we like from scratch, something that’s already finding particular use in medicine, with 3D printed <a href="http://3dprint.nih.gov/collections/prosthetics">customised prosthetics</a> or even <a href="http://www.bbc.co.uk/news/uk-england-hampshire-27436039">replacement bones such as hip joints</a>. Going one step further is to create so-called “<a href="https://theconversation.com/explainer-what-is-4d-printing-35696">4D printed materials</a>” that once created can change their shape.</p>
<p>Following decades of research by chemists, engineers, physicists and biologists this promising field of “smart materials” includes polymer-based (plastic) materials that can drastically change their properties if <a href="http://www.nature.com/nmat/journal/v9/n2/abs/nmat2614.html">triggered by changing environmental factors</a> such as heat, moisture or pH. Now, in a recently published paper, US researchers have demonstrated novel smart materials that can be pre-programmed to shape-shift in specific ways, without the need for an external stimulus to trigger the change.</p>
<p>Smart polymers have been put to many uses. For example, as nanoparticles that only form when a <a href="http://pubs.rsc.org/en/Content/ArticleLanding/2014/CC/c4cc04139a#!divAbstract">solution is shaken</a>, or dissolve to release a pharmaceutical when the nanoparticle is taken up by a <a href="http://pubs.acs.org/doi/abs/10.1021/acs.chemrev.5b00346">living cell</a>. Or nanoparticles that shape-shift into a different type of nanoparticle when the temperature changes, and <a href="http://pubs.acs.org/doi/abs/10.1021/ja3024059">shape-shift back again</a> when the temperature change is reversed. On a much larger scale, smart materials have been used to create <a href="https://application.wiley-vch.de/books/sample/3527318291_c01.pdf">self-healing systems</a>, where the mechanical forces that cause breakages also initialise chemical reactions that glue two broken pieces back together. </p>
<p>What all these smart materials have in common is that they only react to external stimulation. Being able to “program” smart materials to shape-shift without a trigger, as demonstrated in the new paper, is a new achievement.</p>
<h2>Pitting physical against chemical</h2>
<p>Published in Nature Communications, the <a href="http://www.nature.com/articles/ncomms12919">study</a> focuses on the preparation of cylinder-shaped polymer hydrogels: soft pieces of plastic that contain water, similar to the material soft contact lenses are made from. </p>
<p>The usual mechanical behaviour of these plastic cylinders relies on its chemical structure, made up of two sets of bonds between individual chains of polymers. The first type of bonds that hold the cylinder material together are known as chemical crosslinks, which are permanent and do normally not break. The second are the many physical hydrogen bonds that hold the plastic cylinder together. Crucially, while initially stable, these hydrogen bonds can be broken under sufficient stress, becoming soft and then reforming in a different configuration.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/140723/original/image-20161006-14709-1isj1rh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/140723/original/image-20161006-14709-1isj1rh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/140723/original/image-20161006-14709-1isj1rh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=434&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140723/original/image-20161006-14709-1isj1rh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=434&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140723/original/image-20161006-14709-1isj1rh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=434&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140723/original/image-20161006-14709-1isj1rh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=545&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140723/original/image-20161006-14709-1isj1rh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=545&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140723/original/image-20161006-14709-1isj1rh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=545&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diagram showing how polymer chains (top) break and reform in new shapes as time progresses (bottom).</span>
<span class="attribution"><a class="source" href="http://www.naure.com/articles/ncomms12919#f1">Xiaobo Hu et al/Nature</a></span>
</figcaption>
</figure>
<p>Left for enough time – perhaps days – this material will eventually assume the shape in which the strong chemical crosslinks are least strained. This is just the same as how a rubber band returns to its original resting shape after having been stretched (only a rubber band moves much faster). </p>
<p>In the study, the researchers forced one of their smart material cylinders into a specific shape for a period of time. While deformed, the material’s chemical structure attempts to reform into its original shape, just as a rubber band does. However, depending on how long the cylinder is bent out of shape, the physical hydrogen bonds inside the material will break and reform in a way that actually favours the new, bent, shape. </p>
<p>When released, an internal struggle begins inside the cylinder during which its chemical structure attempts to revert to its original shape, but to do so requires the physical network of hydrogen bonds to revert to its original form, which can take some time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/140711/original/image-20161006-14719-ihf11k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/140711/original/image-20161006-14719-ihf11k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/140711/original/image-20161006-14719-ihf11k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=308&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140711/original/image-20161006-14719-ihf11k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=308&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140711/original/image-20161006-14719-ihf11k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=308&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140711/original/image-20161006-14719-ihf11k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=387&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140711/original/image-20161006-14719-ihf11k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=387&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140711/original/image-20161006-14719-ihf11k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=387&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Rose petals made from shape-shifting materials, programmed to open one after the other, with the bud opening into a flower.</span>
<span class="attribution"><a class="source" href="http://www.nature.com/articles/ncomms12919#f4">Xiaobo Hu et al/Nature</a></span>
</figcaption>
</figure>
<h2>Timing is crucial</h2>
<p>The authors demonstrated that the time the material requires to revert to its original shape depends on how long it is held bent out of shape. The longer it spends deformed, the more the physical connections become accustomed to the new change and the longer it takes for the cylinder to relax back. </p>
<p>Impressively, this means the researchers were able to show that one of their smart material cylinders could be programmed to perform a specific routine by applying several bends, each held for different lengths of time. They were also able to program a time lag, applying a thin water-soluble coating to the cylinder which prevents the cylinder from starting its shape-shifting until the coating becomes soft from immersion in water.</p>
<p>Given the large and growing interest in smart materials, this research offers an interesting new approach to their design and manipulation. Adding the element of timing and trigger-free activation into the design of smart materials offers all sorts of uses, for example home products that adapt to heat or moisture. And of course there’s enormous potential for biomedical treatments, such as minimally invasive surgical procedures, autonomous actuators, slow-release methods for drugs, or physical implants that respond to environmental changes, even within the body.</p><img src="https://counter.theconversation.com/content/66622/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Roth 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>Programmable materials that can change shape could have all manner of potential uses.Peter Roth, Lecturer in Applied Organic Chemistry, University of SurreyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/617732016-06-29T09:48:53Z2016-06-29T09:48:53ZTiny wings trapped in amber 99 million years ago reveal new secrets of earliest birds<figure><img src="https://images.theconversation.com/files/128559/original/image-20160628-7832-evjbo.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Royal Saskatchewan Museum/RC McKellar</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Fossilised amber is like a time capsule, a snapshot into a world millions of years old, and ancient creatures discovered in this amber give us fascinating insights into the past. </p>
<p>The amber deposits of north-east Myanmar (Burma) have become famous for thousands of fossils that preserve an astonishing array of plants, insects, spiders, scorpions and lizards from the Cretaceous period that were unfortunate enough to become trapped in the sticky sap of ancient trees – sap which over millions of years becomes amber. Rarely, collectors have found isolated feathers, and even more rarely parts of ancient birds. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/128555/original/image-20160628-7840-uahzv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/128555/original/image-20160628-7840-uahzv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/128555/original/image-20160628-7840-uahzv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/128555/original/image-20160628-7840-uahzv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/128555/original/image-20160628-7840-uahzv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/128555/original/image-20160628-7840-uahzv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/128555/original/image-20160628-7840-uahzv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/128555/original/image-20160628-7840-uahzv.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">Fossils of the early bird <em>Confuciusornis sanctus</em> from the Jehol group.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Confuciusornis_sanctus.jpg">Edward Sola</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Xing Lida from the China University of Geosciences in Beijing, together with a large team including myself, are among those to make such a rare discovery: two tiny fossil wings preserved complete with feathers, as detailed <a href="http://nature.com/articles/doi:10.1038/ncomms12089">in a paper</a> published in Nature Communications.</p>
<p>Unlike the even more famous <a href="http://palaeo.gly.bris.ac.uk/melanosomes/jehol.html">fossil birds from the Jehol Group</a> of north-east China that are preserved only as imprints in stone, these Burmese fossils are three-dimensional, the first ever discovery of not only the bony skeleton of the wing, but also the feathers in their original arrangement and even the underlying skin.</p>
<p>The two wing fragments from two juveniles of the earliest types of birds are each only around one centimetre long, but following CT scanning the bones are clearly visible. Attached to the back of the ulna and metacarpals – the bones that would in a human be the forearm and fingers – are nine primary and five secondary flight feathers, evenly spaced, and in their original positions. These feathers are asymmetrical, with a vane (the feather’s body) of unequal size to either side of the quill, the feather’s central shaft. This asymmetry is usually interpreted as evidence that the feathers were used in flight.</p>
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<a href="https://images.theconversation.com/files/128562/original/image-20160628-7825-s2wqdc.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/128562/original/image-20160628-7825-s2wqdc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/128562/original/image-20160628-7825-s2wqdc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/128562/original/image-20160628-7825-s2wqdc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/128562/original/image-20160628-7825-s2wqdc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/128562/original/image-20160628-7825-s2wqdc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/128562/original/image-20160628-7825-s2wqdc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/128562/original/image-20160628-7825-s2wqdc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Close-up of the wing showing the feathers’ barbs and barbules.</span>
<span class="attribution"><span class="source">Royal Saskatchewan Museum/RC McKellar</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Just as with feathers from modern birds, when examined in detail the feathers reveal barbs – the ridged formations on a bird’s feathers – and barbules – tiny hooks on the barbs – that allow the separate feathers to “zip” closely together to form a continuous flight surface so the bird can fly. It also enables ruffled feathers to be preened and smoothed back into shape. There are even visible traces of plumage colour – light and dark patches – but it’s impossible to explore the chemistry and potential original colours while the feathers are entirely encased in amber.</p>
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<img alt="" src="https://images.theconversation.com/files/128563/original/image-20160628-7851-dsttr5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/128563/original/image-20160628-7851-dsttr5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=469&fit=crop&dpr=1 600w, https://images.theconversation.com/files/128563/original/image-20160628-7851-dsttr5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=469&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/128563/original/image-20160628-7851-dsttr5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=469&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/128563/original/image-20160628-7851-dsttr5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=590&fit=crop&dpr=1 754w, https://images.theconversation.com/files/128563/original/image-20160628-7851-dsttr5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=590&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/128563/original/image-20160628-7851-dsttr5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=590&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ultraviolet light reveals the direction of flow of the amber.</span>
<span class="attribution"><span class="source">Royal Saskatchewan Museum/RC McKellar</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The anatomy of the bones shows that both specimens belong to enantiornithines, a group of birds that dominated the skies in the Cretaceous period, but died out during the same great mass extinction that killed off the dinosaurs 66m years ago. These are early birds, so they still had three fully-formed fingers with claws, like their dinosaurian ancestors, that could grasp branches in order to climb trees. In comparison, modern birds retain the three fingers, but they cannot grasp and have lost the claws.</p>
<p>The specimens also tell us something of the moment these birds met their fate: small scratch marks visible in the amber suggest one of the little birds was scrabbling to free itself. The fact that only one wing is preserved in each case perhaps tells us something too: we can assume these tiny birds, each with stumpy wings that are little larger than a man’s thumbnail, were clambering about on tree branches perhaps in search of insects or fruit to eat. They blundered into the tree sap and their feathers became entangled. The more they struggled, the more their feathers became stuck, and as the amber hardened they could not escape. The rest of their bodies decayed and fell away, leaving just two pristine little wings preserved forever.</p>
<p>Apart from this vivid vignette of life and death 99m years ago, these wings offer the hope of more such discoveries. When the Jehol birds were found in China in the 1990s, they revolutionised our understanding of the early history of birds. The chance of finding feathers and soft tissues from these times means palaeontologists can flesh out more details in their understanding of the earliest birds. This is important: birds today are one of the most successful groups of animals with 10,000 species. In terms of biodiversity and conservation of these species, we need to know why they are so successful.</p><img src="https://counter.theconversation.com/content/61773/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Benton receives funding from NERC and the Leverhulme Trust. </span></em></p>For the first time, feathers, bone and skin of the earliest birds have been found, trapped in amber.Michael J. Benton, Professor of Vertebrate Palaeontology, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/556192016-03-03T05:39:35Z2016-03-03T05:39:35ZChronic stress effects help cancer spread, researchers find<figure><img src="https://images.theconversation.com/files/113635/original/image-20160302-25879-17wt03c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Prolonged periods of stress can aid in the spread of cancer.</span> <span class="attribution"><span class="source">from shutterstock.com</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Chronic stress accelerates cancer growth in mice, according to a <a href="http://www.nature.com/ncomms/2016/160301/ncomms10634/full/ncomms10634.html">paper published in Nature Communications</a> this week. The finding points to potential treatment targets to slow the progression of cancer to other organs.</p>
<p>The paper revealed findings from several studies, mostly on mice, conducted by a team of researchers from Monash University.</p>
<p>Chronic stress refers to prolonged, repeated exposure to stressful situations, such as caring for a sick relative for a long period of time. To mimic the way people feel under significant stress, researchers restrained mice with breast cancer tumours, to make them feel like they couldn’t cope with their circumstances.</p>
<p>Over time, the mice developed an increase in the number and size of of their lymphatic vessels – a network of vessels that transports fluid around the body. This enhanced the spread of cancer cells to new sites, a process called cancer progression or metastasis.</p>
<p>By blocking the activity of proteins that detect stress, or those that enhance the formation of lymphatic vessels, researchers found they could reduce the spread of cancer cells in the mice. </p>
<h2>What stress does to the body</h2>
<p>The research focused on metastasis of breast cancer to other parts of the body, building on previous findings that neurological stress hinders our defence against disease.</p>
<p>Previous findings <a href="http://www.nature.com/nrclinonc/journal/v5/n8/full/ncponc1134.html">from human studies</a> have shown poorer cancer survival in people exposed to stressful life experiences and those more prone to stress. </p>
<p>Another <a href="http://onlinelibrary.wiley.com/doi/10.1002/cncr.23969/abstract;jsessionid=5F1E795CA48D6B71FC0A85B45799D348.f04t03">clinical trial</a> showed better survival rates for breast cancer patients in remission who participated in a 12-month intervention with strategies to reduce stress, improve mood and alter health behaviours.</p>
<p>Everyday stressful experiences pose a threat to the body’s natural balance. This is because stress activates the <a href="https://www.sciencedaily.com/terms/sympathetic_nervous_system.htm">sympathetic nervous system (SNS)</a>, which is responsible for what we know as the fight or flight response. </p>
<p>Under stress, the SNS releases higher levels of neurotransmitters. These hormones, such as epinephrine, signal to other cells to activate physiological flight or flight responses, such as a faster heart rate. This is important during times of threat because it makes us more alert and increases physiological functions needed for rapid reactions.</p>
<p>But as shown in the Nature Communications study, chronic periods of stress can lead to changes in the lymphatic system. These include an increase in the number of vessels in the tumours as well as the size of these vessels. These changes are associated with the spread of cancer cells to lymph nodes and distant organs, such as the lung. </p>
<p>Clinically, we know that when cancer cells have spread through blood vessels into the lymph vessels, that’s an important indicator of poorer prognosis. Preventing this could improve survival rates.</p>
<h2>It’s not so simple</h2>
<p>The latest findings have obvious treatment implications, which include using drugs to block stress responses that lead to changes in lymphatic vessels. But blocking any part of a natural pathway can promote a cascade of negative effects.</p>
<p>The study reported that a number of patients on drugs often used to treat anxiety and high blood pressure (beta blockers that block the actions of adrenaline) were less likely to have secondary cancer that had spread from its primary site. </p>
<p>This is good news, but more work is needed before such interventions can be further tested. </p>
<p>This is because the lymphatic system is important in our immune response and manipulating any of its mechanisms could carry potential harms. These include limiting the immune system’s ability to respond to the cancer in the first place. </p>
<p>It could also increase the risk of lymphedema – swelling in one or more extremities – that results from impaired flow of the lymphatic system.</p>
<p>Although the authors did show supportive data from human clinical subjects, the bulk of the work was done in mouse models. Results from mice experiments don’t always translate to human systems, so further clinical testing is an essential step in translating these findings.</p>
<p>Overall, though, the study points the way to potentially helping prevent cancer spreading so far from the original site that it’s too hard to treat.</p><img src="https://counter.theconversation.com/content/55619/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Chronic stress accelerates cancer growth in mice, according to a new study, pointing to potential treatment targets to slow the progression of cancer to other organs.Rik Thompson, Professor of Breast Cancer Research, Institute of Health and Biomedical Innovation and School of Biomedical Sciences,, Queensland University of TechnologySandra Hayes, Professor, School of Public Health and Social Work, Queensland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/403612015-04-22T10:04:08Z2015-04-22T10:04:08ZInvisible fluorescent ink opens new frontier in fight against counterfeiting<figure><img src="https://images.theconversation.com/files/78852/original/image-20150422-9051-mutnu2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fluorescent security ink produces multicolor barcode visible under UV light.</span> <span class="attribution"><span class="source">Stoddart Group</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Counterfeiting gives brand owners major headaches. Companies lose sales and governments lose tax income. Resulting costs to businesses of counterfeit and pirated products add up to as much as <a href="http://www.iccwbo.org/Data/Documents/Bascap/Global-Impacts-Study-Full-Report/">US$650 billion a year</a> worldwide, according to the International Chamber of Commerce.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/78843/original/image-20150421-9051-ognfxs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/78843/original/image-20150421-9051-ognfxs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/78843/original/image-20150421-9051-ognfxs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=330&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78843/original/image-20150421-9051-ognfxs.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=330&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78843/original/image-20150421-9051-ognfxs.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=330&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78843/original/image-20150421-9051-ognfxs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=414&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78843/original/image-20150421-9051-ognfxs.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=414&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78843/original/image-20150421-9051-ognfxs.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=414&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">100 Euro bill under UV light.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:100euro-uv.JPG">European Central Bank</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Scientists and engineers have developed many techniques in the fight against counterfeiters. You might have one example in your pocket right now – the banknotes we use almost every day are produced using special paper, with watermarks, holograms, glossy strips and many other security features. When we hand a large-denomination bill to a cashier, they usually look at it under an ultraviolet lamp to check whether it’s genuine or fake. Under this light, one can see a color image that’s not visible in plain sunlight. Lights that glow under a UV lamp are said to be fluorescent or luminescent. Similar fluorescent tags on our driver’s licenses and passports are also designed to glow under ultraviolet light.</p>
<p>Although these fluorescent materials have been implemented widely in order to protect high-value merchandise, government documents and banknotes, they have a weakness: once their recipes are familiar to counterfeiters, they can be mimicked rather easily.</p>
<p>Now <a href="http://dx.doi.org/10.1038/ncomms7884">we’ve invented next-generation fluorescent inks</a> that will present a formidable challenge to counterfeiters. Images printed from these new inks display colors that depend on a type of built-in “molecular encryption” and become visible only when viewed under ultraviolet light. Each user can select his own ink recipes, so even we the inventors will not be able to mimic the protected fluorescent tag. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/78828/original/image-20150421-9051-h3d6s0.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/78828/original/image-20150421-9051-h3d6s0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/78828/original/image-20150421-9051-h3d6s0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=126&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78828/original/image-20150421-9051-h3d6s0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=126&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78828/original/image-20150421-9051-h3d6s0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=126&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78828/original/image-20150421-9051-h3d6s0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=158&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78828/original/image-20150421-9051-h3d6s0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=158&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78828/original/image-20150421-9051-h3d6s0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=158&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Representation of a heterorotaxane.</span>
<span class="attribution"><span class="source">Stoddart Group</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Creating the ink</h2>
<p>This new ink has its roots in a serendipitous discovery we made when trying to make a fluorescent molecule that would contain some ring-shaped molecules. Unexpectedly, we isolated a compound – known as heterorotaxane – which has become our invisible ink’s active ingredient. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/78647/original/image-20150420-25694-1i84c3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/78647/original/image-20150420-25694-1i84c3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/78647/original/image-20150420-25694-1i84c3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=252&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78647/original/image-20150420-25694-1i84c3a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=252&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78647/original/image-20150420-25694-1i84c3a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=252&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78647/original/image-20150420-25694-1i84c3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=317&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78647/original/image-20150420-25694-1i84c3a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=317&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78647/original/image-20150420-25694-1i84c3a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=317&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) Van Gogh’s Sunflower printed using our b) fluorescent ink under ultraviolet light and c) sunlight.</span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>On its own, the heterorotaxane glows dark-red under ultraviolet light. But its unusual arrangement of molecules can be interrupted by adding a sugar, namely cyclodextrin, which is derived from cornstarch. Depending on how much cyclodextrin we add and how it interacts with the heterorotaxane, we can adjust our ink to give different fluorescent colors along a spectrum of red to yellow to green. </p>
<p>On a molecular level, the colorless heterorotaxane interacts with the other components of the ink. It selectively encapsulates some parts and prevents other molecules from sticking to one another – ultimately causing a change in color that is somewhat difficult to predict. This is a level of complexity not seen before in anti-counterfeiting tools.</p>
<p>Our inks are similar to the proprietary formulations of soft drinks. One could approximate their flavor using other ingredients, but it would be impossible to match the flavor exactly without a precise knowledge of the recipe.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/78641/original/image-20150420-25725-g3ummz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/78641/original/image-20150420-25725-g3ummz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/78641/original/image-20150420-25725-g3ummz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=311&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78641/original/image-20150420-25725-g3ummz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=311&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78641/original/image-20150420-25725-g3ummz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=311&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78641/original/image-20150420-25725-g3ummz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=391&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78641/original/image-20150420-25725-g3ummz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=391&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78641/original/image-20150420-25725-g3ummz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=391&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fluorescent inks change color under ultraviolet light when printed on different paperstocks.</span>
<span class="attribution"><span class="source">Stoddart Group</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Not only that, the fluorescent ink is also sensitive to the surface on which it’s applied. For example, an ink blend that appears orange on standard copy paper appears as green on newspaper. This phenomenon means that this new type of fluorescent ink can be used to identify different papers.</p>
<h2>Encrypting and authenticating</h2>
<p>Think about <a href="http://en.wikipedia.org/wiki/Encryption">encryption processes</a> in computer science. <a href="http://en.wikipedia.org/wiki/Cryptography">Cryptography algorithms</a> protect the original information and transform the data into a set of “random” information that gets decoded by a recipient.</p>
<p>Our fluorescent inks work in a similar way. The “molecular encryption” process involves picking a set of color-changing agents and playing around with their relative proportions. Users can set their parameters, thus generating thousands of color combinations via different settings. The individual secret ink recipe can be printed out via ordinary ink jet printer onto a label or other tag. It’s impossible to reverse engineer the process without comprehensive knowledge of the encryption settings. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/78644/original/image-20150420-25694-1cpqqlr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/78644/original/image-20150420-25694-1cpqqlr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/78644/original/image-20150420-25694-1cpqqlr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=373&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78644/original/image-20150420-25694-1cpqqlr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=373&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78644/original/image-20150420-25694-1cpqqlr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=373&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78644/original/image-20150420-25694-1cpqqlr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=469&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78644/original/image-20150420-25694-1cpqqlr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=469&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78644/original/image-20150420-25694-1cpqqlr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=469&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fluorescent security ink can have a specific – and unfakeable – fingerprint.</span>
<span class="attribution"><span class="source">Stoddart Group</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>That’s how the information is encoded in the fluorescent dye. But it also has to be verified in some way in order to validate an object as legitimate or counterfeit.</p>
<p>We’ve developed an authentication mechanism that can verify the information within a preexisting image printed using the fluorescent inks. One simply sprays or wipes an authentication indicator over the printed image. While inks with different formulations may appear to be the same color, they will respond very differently when an authentication indicator molecule, such as cyclodextrin, is applied. There’s a large library of authentication indicators that can result in different color changes. This authentication mechanism is a result of the complex molecular interactions among the ink ingredients, so that even if a counterfeiter is able to mimic the original fluorescent color, it will be nigh impossible to replicate the color change during the authentication process.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/78842/original/image-20150421-9038-1gd0rl6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/78842/original/image-20150421-9038-1gd0rl6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/78842/original/image-20150421-9038-1gd0rl6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78842/original/image-20150421-9038-1gd0rl6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78842/original/image-20150421-9038-1gd0rl6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78842/original/image-20150421-9038-1gd0rl6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78842/original/image-20150421-9038-1gd0rl6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78842/original/image-20150421-9038-1gd0rl6.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">Legit or phony? Get out your authenticating wipes and UV light.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/qiaomeng/597433766">Simon A</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>So here’s how it works from start to finish. A luxury manufacturer would pick a secret setting for its proprietary ink. The company would print out a tag for each handbag, for instance, using the ink invisible under normal light. Then each boutique owner or end consumer that buys the products can view the printed tag under UV light to make sure it matches up with the color they’re expecting. And they can also wipe an authentication swab over it to confirm that the changes that come from that particular combination of authenticating molecules and printed ink are identical to what the manufacturer has told them they should see. Counterfeiters will be out of luck since essentially this process can’t be mimicked.</p><img src="https://counter.theconversation.com/content/40361/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fraser Stoddart is affiliated with Northwestern University.</span></em></p><p class="fine-print"><em><span>Chenfeng Ke is affiliated with Northwestern University. </span></em></p><p class="fine-print"><em><span>Xisen Hou 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>Invisible under normal light but fluorescent under UV light, this ink can print out unique signatures that use ‘molecular encryption’ to authenticate anything they tag.Fraser Stoddart, Professor of Chemistry, Northwestern UniversityChenfeng Ke, Postdoctoral Fellow in Chemistry, Northwestern UniversityXisen Hou, PhD Student in Chemistry, Northwestern UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/308702014-08-26T20:47:41Z2014-08-26T20:47:41ZNew cancer-hunting ‘nano-robots’ to seek and destroy tumours<figure><img src="https://images.theconversation.com/files/57350/original/m6yc6b7r-1409021734.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">They have cancer in their sights.</span> <span class="attribution"><a class="source" href="http://www.flickr.com/photos/stephenliveshere/526355669">StephenMitchell/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>It sounds like a scene from a science fiction novel – an army of tiny weaponised robots travelling around a human body, hunting down malignant tumours and destroying them from within.</p>
<p>But research in <a href="http://dx.doi.org/10.1038/ncomms5712">Nature Communications today</a> from the University of California Davis Cancer Centre shows the prospect of that being a realistic scenario may not be far off. Promising progress is being made in the development of a multi-purpose anti-tumour nanoparticle called “nanoporphyrin” that can help diagnose <em>and</em> treat cancers.</p>
<p>Cancer is the <a href="https://theconversation.com/cancer-the-worlds-biggest-killer-22762">world’s biggest killer</a>. In 2012, an estimated 14.1 million new cancer cases were diagnosed and around <a href="http://www.who.int/mediacentre/factsheets/fs297/en/">8.2 million people</a> died from cancer worldwide. </p>
<p>This year, cancer <a href="http://www.abc.net.au/news/2014-02-04/cancer-now-biggest-killer-in-australia/5236148">surpassed cardiovascular diseases</a> to become the leading cause of death in Australia; 40,000 Australians died as a result of cancer last year. It’s no wonder that scientists explore every possible technology to efficiently and safely diagnose and treat the disease.</p>
<p>Nanotechnology is one such revolutionary cancer-fighting technology.</p>
<h2>Nanotech: a big deal</h2>
<p>A nanometre is a very small unit of length, just one billionth of a metre. Nanotechnology looks at building up incredibly tiny, nano-level structures for different functions and applications. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/38Vi8Dm0kdY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How small is a nanoparticle, really?</span></figcaption>
</figure>
<p>One such nanoparticle-based application is the development of precise cancer diagnostic technology and safe, efficient tumour treatment. The only problem is nanoparticles must be tailored to specific jobs. They can be time-consuming and expensive to research and build.</p>
<p>So how do nanoparticles work? They can be made using inorganic or organic components. Each has different properties:</p>
<ul>
<li>Inorganic nanoparticles often have unique properties that make them useful in applications such as fluorescence probes and magnetic resonance imaging tumour diagnoses;</li>
<li>“Soft” organic nanoparticles are the best drug-delivery carriers for tumour treatment, due to their biocompatibility, ability to be chemically modified and their drug-loading capacity. A few “soft” organic nanomedicines including Genexol-PM (paclitaxel-loaded polymeric micelles), Doxil (liposomal doxorubicin) and Abraxane (paclitaxel-loaded human serum albumin nanoaggregate) have been approved or are in clinical trials for the treatment of human cancers.</li>
</ul>
<p>The new organic nanoparticle – nanoporphyrin – can do all this.</p>
<h2>Ins and outs of nanoporphyrin</h2>
<p>Nanoporphyrin is only 20-30 nanometres in size. If you want to get technical, it’s a self-assembled micelle consisting of cross-linkable amphiphilic dendrimer molecules containing four <a href="http://www.britannica.com/EBchecked/topic/470697/porphyrin">porphyrins</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/57343/original/gy8m2wcv-1409020766.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/57343/original/gy8m2wcv-1409020766.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/57343/original/gy8m2wcv-1409020766.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=602&fit=crop&dpr=1 600w, https://images.theconversation.com/files/57343/original/gy8m2wcv-1409020766.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=602&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/57343/original/gy8m2wcv-1409020766.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=602&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/57343/original/gy8m2wcv-1409020766.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=756&fit=crop&dpr=1 754w, https://images.theconversation.com/files/57343/original/gy8m2wcv-1409020766.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=756&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/57343/original/gy8m2wcv-1409020766.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=756&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Structure of porphine, the simplest porphyrin.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>If you want to get less technical, it’s a loosely bound group of molecules (or “micelle”) with their hydrophilic (“water-loving”) heads pointing outwards and their hydrophobic (“water-hating”) tails pointing inwards. Each molecule contains organic compounds called porphyrins. Porphyrins can occur naturally, the best-known being heme, the pigment in red blood cells.</p>
<p>Nanoporphyrin’s small size gives it an intrinsic advantage as it can be engulfed by and accumulate in tumour cells, where it can act on two levels:</p>
<ol>
<li>On the molecule level, nanoporphyrin can aid diagnosis by enhancing the contrast of tumour tissue in magnetic resonance imaging (<a href="https://theconversation.com/the-science-of-medical-imaging-magnetic-resonance-imaging-mri-15030">MRI</a>), positron emission tomography (<a href="https://theconversation.com/the-science-of-medical-imaging-spect-and-pet-14086">PET</a>) and dual modal PET-MRI. (Again, this is a bit technical, but if you’re interested, porphyrin acts as a ligand, which chelates with imaging agent metal ions such as gadolinium (III) or ⁶⁴copper (II).)</li>
<li>on the micelle level, nanoporphyrin can be loaded with anti-tumour drugs to kill malignant tissue. When activated, for example, it can generate heat to “cook” the tumour tissue, and release lethal reactive oxygen species (ROS) at tumour sites. </li>
</ol>
<h2>Armed and dangerous (to tumours)</h2>
<p>Functional nanoparticle processes can be similar to those of an armed nano-robot. For example, when a tumour-recognition module is installed in a delivery nano-robot (organic particle), the armed drug-loaded nano-robot particles can target and deliver the drug into tumour tissue. They kill only those cells, while being harmless to surrounding healthy cells and tissues. </p>
<p>If a tumour-recognition module is installed in a probe nano-robot (inorganic particle), the armed nano-robot particles can get into tumour tissue and activate a measurable signal to help doctors better diagnose tumours.</p>
<p>It has been a huge challenge to integrate these functions on the one nanoparticle. It’s difficult to combine the imaging functions and light-absorbing ability for phototherapy in organic nanoparticles as drug carriers. This has, until now, hampered development of smart and versatile “all-in one” organic nanoparticles for tumour diagnosis and treatment.</p>
<p>The production of nanoporphyrin is an efficient strategy in the development of multifunctional, integrated nanoparticles. The same strategy could be used to guide further versatile nanoparticle platforms to reduce nanomedicine costs, develop personalised treatment plans and produce self-assessing nanomedicines.</p><img src="https://counter.theconversation.com/content/30870/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Liu 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>It sounds like a scene from a science fiction novel – an army of tiny weaponised robots travelling around a human body, hunting down malignant tumours and destroying them from within. But research in Nature…Jason Liu, Postdoctoral Researcher in Nanoparticles, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/295982014-07-24T05:09:32Z2014-07-24T05:09:32ZRevealed: bats use sunsets to reset their magnetic compasses and fly in the dark<figure><img src="https://images.theconversation.com/files/54685/original/c6jppwnk-1406129431.jpg?ixlib=rb-1.1.0&rect=572%2C502%2C1769%2C1009&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Holy sunsets, the bat knows where to go!</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/22032337@N02/5520347827">Steve Garner</a></span></figcaption></figure><p>“Blind as a bat” goes the saying – but that’s a myth. Small bats have perfectly good eyesight for their size, but they can also call upon “extra senses” which humans can only achieve with technology. These include the famous ability to navigate using echoes of sounds and the ability to track Earth’s magnetic field based on light from sunsets.</p>
<p>Bats use echoes to <a href="http://www.bats.org.uk/pages/echolocation.html">hunt and navigate around familiar areas</a>. However, studies from the late 1960s have shown that beyond a certain distance (about 10 miles), they need something else to navigate. </p>
<p>If a bat is to return home from an unfamiliar place, it needs something like a compass and a map to tell it where it is and where to fly. In other animals, such as birds, we have known how they do this for a long time.</p>
<p>But research on the flying mammals has for some reason lagged behind. In part, it may be because of the difficulty of studying small and highly mobile nocturnal animals. With the help of some colleagues, some eight years ago, I set out to discover the map and compass bats used to navigate. Our recent results have now been published in the journal <a href="http://dx.doi.org/10.1038/ncomms5488">Nature Communications</a>.</p>
<p>The first place to look was to find if bats have magnetic sense, which is <a href="http://www.economist.com/blogs/economist-explains/2013/07/economist-explains-11">what birds use</a> when faced with similar navigation challenges. To do that, we put bats that we had captured at a local barn in a box with an electromagnetic coil. When inside, the box changed the direction of the magnetic field of the surrounding area by 90 degrees. Once the sun had set, the pigeons were let out, after fitting a small radio transmitter to their backs and displacing them 20km north of the home roost. </p>
<p>The transmitter allowed us to track the paths the pigeons took. What we found was that bats that had been in the altered magnetic field flew off in a path that was deflected by 90 degrees compared to the bats that hadn’t been in an altered magnetic field. But this only happened when those bats in the altered magnetic field were released after the sun had set. If they were put in an altered magnetic field and release before sunset, they flew home without any deflection. </p>
<p>It seemed then that bats, like birds, calibrate their magnetic compasses based on cues observed at sunset. But what could these cues be? </p>
<p>The most obvious seems to be the sun’s position. Unlike the Earth’s magnetic field, which can be variable depending on location, the sun predictably sets in certain locations throughout the year. Thus, if the bats could learn that position, this would be a reliable cue on which to calibrate the magnetic compass. </p>
<p>To test this, instead of putting them in altered magnetic fields, the bats were shown a mirror at sunset. It was angled such that the sun appeared deflected by 90 degrees. Then, when released, we observed the bats’ flight path. But the mirror seemed to have had no effect on their orientation. Clearly, something else must be going on.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/54677/original/3h4rjbg7-1406125252.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/54677/original/3h4rjbg7-1406125252.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/54677/original/3h4rjbg7-1406125252.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/54677/original/3h4rjbg7-1406125252.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/54677/original/3h4rjbg7-1406125252.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/54677/original/3h4rjbg7-1406125252.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/54677/original/3h4rjbg7-1406125252.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/54677/original/3h4rjbg7-1406125252.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bats sit in a box with polarisation filters at sunset.</span>
<span class="attribution"><span class="source">Stefan Greif</span></span>
</figcaption>
</figure>
<p>Perhaps bats, like birds again, used the pattern of polarised light at sunset and sunrise to calibrate a magnetic compass. Polarisation measures the angle at which light waves move in relation to the direction in which they are travelling. Human eyes don’t have the ability to detect the differences in polarisation. </p>
<p>The polarisation cue appears as a dark band running across the sky from north to south as the sun sets in the west. To test our hypothesis, we put our bats into boxes with polarisation filters that changed this pattern so that it was rotated by 90 degrees. Then the birds were released from the boxes after sunset and 20km away from from home. </p>
<p>This time we found that their paths were indeed deflected by 90 degrees, compared to bats that had been in boxes that mimicked the natural polarisation pattern. This is exactly how they had reacted when their magnetic orientation was altered after sunset.</p>
<p>So it seems that bats use the Earth’s magnetic field as a compass, and that this is calibrated by the pattern of polarised light at sunset. This makes bats the first mammal we know to show the use of such cues for navigation. </p>
<p>Although this is an exciting result, it raises the question of how the light-sensitive cells in bat’s eyes have adapted to detect it. Also, it only provides the answer to how bats’ compasses help them set off in the right direction. We still need to find out how bats work out their position to navigate long distances in the dark.</p>
<hr>
<p><em>Next, read this: <a href="https://theconversation.com/explainer-how-do-homing-pigeons-navigate-25633">how do homing pigeons navigate?</a></em></p><img src="https://counter.theconversation.com/content/29598/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Holland receives funding from Marie Curie FP6, NERC</span></em></p>“Blind as a bat” goes the saying – but that’s a myth. Small bats have perfectly good eyesight for their size, but they can also call upon “extra senses” which humans can only achieve with technology. These…Richard Holland, Lecturer in Animal Cognition, Queen's University BelfastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/267692014-05-16T13:37:57Z2014-05-16T13:37:57ZDiscard ban can benefit fish and fishers, but sustainability must come first<p>It was hailed as a great victory for conservation, common sense and people power. Last year the European Commission finally <a href="http://www.theguardian.com/environment/2013/dec/13/eu-discards-ban-fish-seas">voted to phase out</a> the shameful practice of discarding hundreds of thousands of tonnes of perfectly good fish, either by-catch or target species caught over the allowable quota, as permitted by the EU <a href="http://ec.europa.eu/fisheries/cfp/index_en.htm">Common Fisheries Policy</a> (CFP). </p>
<p>Although hundreds of scientists, NGOs, politicians and legislators worked behind the scenes to make this happen, the issue really hit the public consciousness through the work of the mop-haired part-time celebrity chef/eco-warrior, Hugh Fearnley Whittingstall. His <a href="http://www.fishfight.net">Fish Fight</a> TV series exposed the images of tonnes of dead fish being dumped overboard to the public. In fact his campaign was so successful that over 870,000 people signed his petition to end discards, and he was granted personal meetings with <a href="http://ec.europa.eu/commission_2010-2014/damanaki/index_en.htm">Maria Damanaki</a>, the European Fisheries Commissioner.</p>
<p>So why are we now seeing headlines suggesting the <a href="http://www.bbc.co.uk/news/uk-scotland-glasgow-west-27391232">discard ban could actually harm wildlife</a>, and that <a href="http://www.thetimes.co.uk/tto/environment/article4088866.ece">Fish Fight’s campaign was misleading</a>? Hugh was even given the Paxman treatment in a <a href="https://www.youtube.com/watch?v=2x-leiuLTyY">debate on Newsnight</a>. </p>
<p>This renewed interest has been spurred by the <a href="http://www.nature.com/ncomms/2014/140513/ncomms4893/full/ncomms4893.html">publication of a paper</a> in the journal Nature Communications by Professor Mike Heath and colleagues at the University of Strathclyde that examines the knock-on effects of a discard ban. </p>
<p>Using an ecosystem model of the North Sea, the paper’s authors examined the effect of two different management approaches. The first simulated the fishers’ obligation to land all catch (the discard ban), including undersize (ie, juvenile) or unwanted (ie, by-catch) fish, by inflating the landing quotas accordingly. The second simulated the same landing obligation, but added an element which added fishers efforts to be more selective and avoid unwanted catch by maintaining lower quotas.</p>
<p>Not surprisingly, the first option had negative effects on marine ecosystems. Not only would it result in increased pressure on fish stocks – it removes more fish from the sea – but by removing the discards it would also remove a source of food scavenged upon by seabirds, marine mammals and seabed creatures. There might be some short-term economic benefits to fishers, but in the long term the catch rates are likely to be unsustainable, and the oceans in general will suffer.</p>
<p>This is the story that has been seized upon by the media and some sections of the fishing industry, because it is the option being considered by the European Commission. Surely no one is suggesting that we go back to the bad old days and try to maintain a marine ecosystem that relies on us throwing away 30-40% of the fish we catch each year? In the North Sea alone, this is can account for <a href="http://www.nature.com/ncomms/2014/140513/ncomms4893/full/ncomms4893.html">hundreds of thousands of tonnes</a> each year. And despite some <a href="http://www.nffo.org.uk/news/the_proof.html">counter-claims</a> this week, this rate of discarding has remained <a href="http://www.nature.com/ncomms/2014/140513/ncomms4893/full/ncomms4893.html">relatively constant</a> for several decades. </p>
<p>The second management scenario, which encourages more selective fishing, has to be the better way to go. That way catch rates are more sustainable, scientists gain better data on the fisheries, and the previously discarded material stays in the sea where it can be part of a more natural food chain.</p>
<p>What evidence is there that the discard ban, or to be more politically correct, landing obligation, will work? Discard bans have been <a href="http://www.sciencedirect.com/science/article/pii/S0308597X1300198X">successfully implemented elsewhere in the world</a>, including in the Alaskan and British Columbian groundfish trawl fisheries, and fisheries in New Zealand, Icelandic, Faroese and Norwegian waters. </p>
<p>A couple of years ago one of my MSc students, Ben Diamond, and I <a href="http://bit.ly/QQkKcz">examined the effectiveness</a> of the Norwegian discard ban and whether or not a similar policy should be introduced to the North Sea. Norway introduced a discard ban for cod and haddock in 1987, and has progressively applied it to more species since. Instead of increasing pressure on fish stocks, the discard ban, in combination with real-time closures of waters that contain high concentrations of juvenile fish, has encouraged fishermen to install fishing gear modifications that are more selective in the fish they catch. </p>
<p>As a result, improving data and understanding of fishing mortality has led to better management advice and more sensible fishing quotas. There were some short-term economic costs to the fishing industry, but today the Norwegian and Barents Sea fisheries are among the most prosperous in the world. It’s about time that a similar system is introduced in the North Sea, and in fact as widely as possible throughout European waters. </p>
<p>When the European Commission comes to decide on how to implement the CFP reform, we must hope it will ignore those lobbying for short-term interests, and instead take note of the long-term success of our northern neighbours.</p><img src="https://counter.theconversation.com/content/26769/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bryce Stewart 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>It was hailed as a great victory for conservation, common sense and people power. Last year the European Commission finally voted to phase out the shameful practice of discarding hundreds of thousands…Bryce Stewart, Lecturer in Marine Ecosystem Management, University of YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/266552014-05-13T15:40:43Z2014-05-13T15:40:43ZCoral reefs work as nature’s sea walls – it pays to look after them<p>Coral reefs: fragile, delicate, and in danger? Actually coral reefs can be the first line in defence against incoming storms, reducing the power of incoming waves by 97%, even during hurricane-force winds. Most (86%) of this wave energy reduction happens at the reef crest, a thin narrow band at the highest point of the reef where waves break first.</p>
<p>Our <a href="http://dx.doi.org/10.1038/ncomms4794">study</a> published in the journal Nature Communications found that the risk reduction provided by reefs is relevant to some 200m people worldwide, and it is these people that may have to bear the costs if reefs continue to be degraded. These are the people in the villages, towns, and cities in low-lying, risk-prone coastal areas below <a href="http://www.maps.coastalresilience.org/global">10 metres elevation and within 50km of coral reefs</a>, mostly in Indonesia, India, and the Philippines. You may be surprised to learn that the US is ranked seventh on this list of nations, due to the high density of cities living near the reefs around south-east Florida. We conducted a more conservative analysis, looking at only those living below 10 metres elevation and within just 10km of a reef, which still represents 100m people. </p>
<p>The risk these people face is growing because of the rate of coastal development and climate change, compounded by reef loss and degradation in tropical areas. Reef degradation, particularly the kind that we have seen <a href="http://www.theguardian.com/environment/2013/aug/01/caribbean-coral-reef-loss">across the Caribbean</a> has particularly devastating effects. Small reductions in the height of reefs, particularly at the reef crest, means substantially greater wave energy passes through the reef to strike the coastline. If you reduce the height of a breakwater that runs the length of your coast by 30cm (12 inches) – and the loss on coral reefs has sometimes measured much more – then you can expect to see a major impact on the coastlines.</p>
<p>But there is reason for optimism. At a time when towns, cities and countries are making major investments in climate and weather-related hazard protection, we found that coral reef protection makes economic, ecological and practical, risk-reduction sense. The average cost of building artificial breakwaters is US$19,791 per metre, compared to $1,290 per metre for projects focused on coral reef restoration. And of course healthy coral also provides a beautiful tourist attraction and has other benefits for fisheries.</p>
<p>But this restoration has to be done properly. Treating coral reef conservation as a joint exercise with storm risk reduction is a new field of science and practical application. It would pay to heed the lessons of past projects that have sought to use other habitats in this way. Tsunamis and storms across the Indian and Pacific oceans in recent years have spurred much interest in <a href="https://theconversation.com/mangroves-natures-shield-against-typhoons-and-tsunami-21051">restoring mangroves as a storm defence</a>, for example, but some of the mangrove restoration has been poorly conceived – for example, by planting mangroves as “bioshields” in places where they did not naturally occur. These projects are doomed to failure as the mangroves generally die.</p>
<p>On this basis, we don’t suggest creating new reefs in places they did not naturally occur. Reef restoration will almost certainly require adding to the height and complexity of existing reefs in order to enhance their wave-breaking power.</p>
<p>There will inevitably be trade-offs to make between the conservation and risk-reduction goals. Cautious conservation may favour using reef rubble or natural materials to grow the reef, but if these are unavailable, cement or rocks might have to do to. To deliver actual risk reduction means improving those reefs that will protect the most people – not necessarily the most remote and diverse reefs that have often been the focus of conservation.</p>
<p>We know that corals can recover. There has been significant recovery in many places around the world from the severe coral bleaching that occurred in the extremely warm <a href="http://www.coralwatch.org/web/guest/coral-bleaching">El Niño year of 1998</a>. Recovery was most sustained where other stresses on the reef, such as pollution, were managed well. Done well, restoring reefs can be money well spent with many benefits.</p>
<p>We shouldn’t be investing just in grey infrastructure like seawalls and breakwaters that will further degrade coastal habitats. Instead we have the opportunity to also invest cost effectively in “blue” ecological infrastructure – the sea wall nature has provided us.</p><img src="https://counter.theconversation.com/content/26655/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Beck 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>Coral reefs: fragile, delicate, and in danger? Actually coral reefs can be the first line in defence against incoming storms, reducing the power of incoming waves by 97%, even during hurricane-force winds…Michael Beck, Lead Marine Scientist, The Nature Conservancy, University of California, Santa CruzLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/226042014-02-12T14:37:19Z2014-02-12T14:37:19ZCarbon dioxide from exhaust fumes used to make new chemicals<figure><img src="https://images.theconversation.com/files/41369/original/jkk3jxr9-1392208628.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">New source of making chemicals.</span> <span class="attribution"><span class="source">fahrertuer</span></span></figcaption></figure><p>To stop global warming, most governments are advocating reducing the amount of carbon dioxide (CO₂), a greenhouse gas, put into the atmosphere. But some argue that such action <a href="http://www.theguardian.com/environment/2012/oct/11/carbon-capture-storage-climate-change">won’t be enough</a> – we will need to remove CO₂ already present.</p>
<p>The reduction of CO₂ is a big challenge, as it requires large amounts of renewable energy. Until then, short-term solutions to remove CO₂ from fossil fuel power plants is becoming necessary, including carbon capture and storage (CCS). The other option is to use the storage part, as <a href="http://onlinelibrary.wiley.com/doi/10.1002/anie.201308341/abstract">new research</a> from Korea shows, and to use CO₂ directly from exhaust gases to make new chemicals.</p>
<h2>Catch me if you can</h2>
<p>Carbon capture involves the “capture” of CO₂, either by a chemical or physical process. Often CO₂ from a exhaust gas stream is captured by nitrogen containing compounds called amines. The reaction results in the formation of solid chemicals. These can be heated, allowing the CO₂ to be released, which can then be compressed, transported and stored in geological features, such as depleted oil fields, or used as raw material in chemical factories.</p>
<p>Although trees and some microbes can capture CO₂ and use it as fuel, humans have struggled to replicate the process on a large scale. Most chemical reactions involving CO₂ require expensive catalysts, high temperatures, or high pressures to make it react. The most common use of CO₂ as a chemical feedstock is in the formation of urea, which is found in around 90% of the world’s fertilisers.</p>
<p>In the new research, published in the journal <a href="http://onlinelibrary.wiley.com/doi/10.1002/anie.201308341/abstract">Angewandte Chemie</a>, Soon Hong and colleagues from the Institute for Basic Science in South Korea have caught CO₂ from exhaust gas and used it for many reactions that make useful chemicals. One type is called alkynyl carboxylic acid, which has many uses such as making food additives. The other, cyclic carbonate, is used to make polymers for cars and electronics. Cyclic carbonates can also be used in place of phosgene, which is a very reactive and highly toxic chemical that is used as a starting material to make a wide variety of useful products.</p>
<p>Hong also used highly pure CO₂, which is sold at a high price and required lots of energy to make, in the same chemical reactions and found there was hardly any difference in the final yield (the amount of product formed minus wastage).</p>
<h2>Use me if you do</h2>
<p>Like CCS technologies, Hong passes exhaust fumes through a solution of amines, where CO₂ is captured and other gases pass unreacted. Then the resulting salt is heated to yield pure CO₂ for chemical reactions. Hong can recycle the amine solution at least 55 times without loss in yield.</p>
<p>In another research paper just published in <a href="http://dx.doi.org/10.1038/ncomms4091">Nature Communications</a>, Matthias Beller and colleagues at the University of Rostock in Germany show a new reaction that can use CO₂. The reaction is called alkene carbonylation, and it usually required the use of carbon monoxide (CO), which, as home detectors know well, is a highly toxic and flammable gas.</p>
<p>CO₂ has previously been used in the synthesis of carboxylic acids by using diethylzinc as one of the drivers of the reaction. But diethylzinc is flammable in air. Using the reaction Beller can make chemicals are found in varnishes and paints. The researchers carried out a number of reactions but most importantly confirmed that the source of the newly formed C-O bond was CO₂. This work shows CO₂ can be used as a viable alternative to carbon monoxide in carbonylation reactions and increasing the importance of CO₂ in the chemical industry.</p>
<p>While this is good news, these advances don’t offset the energy needed to trap and use CO₂. They will help increase the demand of CO₂ at industrial scale, and may then drive CCS and renewable energy technologies to become cheaper.</p>
<hr>
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<p class="fine-print"><em><span>Jessica Breen receives funding from the Technology Strategy Board.</span></em></p>To stop global warming, most governments are advocating reducing the amount of carbon dioxide (CO₂), a greenhouse gas, put into the atmosphere. But some argue that such action won’t be enough – we will…Jessica Breen, Postdoctoral researcher, University of LeedsLicensed as Creative Commons – attribution, no derivatives.