̽��ֱ�� of Cambridge - Paul Coxon

Next-generation smartphone battery inspired by the gut

sc604 — Wed, 26 Oct 2016 13:41:29 +0000

Researchers have developed a prototype of a next-generation lithium-sulphur battery which takes its inspiration in part from the cells lining the human intestine. ̽��ֱ��batteries, if commercially developed, would have five times the energy density of the lithium-ion batteries used in smartphones and other electronics.

̽��ֱ��new design, by researchers from the ̽��ֱ�� of Cambridge, overcomes one of the key technical problems hindering the commercial development of lithium-sulphur batteries, by preventing the degradation of the battery caused by the loss of material within it. ̽��ֱ��results are reported in the journal Advanced Functional Materials.

Working with collaborators at the Beijing Institute of Technology, the Cambridge researchers based in Dr Vasant Kumar’s team in the Department of Materials Science and Metallurgy developed and tested a lightweight nanostructured material which resembles villi, the finger-like protrusions which line the small intestine. In the human body, villi are used to absorb the products of digestion and increase the surface area over which this process can take place.

In the new lithium-sulphur battery, a layer of material with a villi-like structure, made from tiny zinc oxide wires, is placed on the surface of one of the battery’s electrodes. This can trap fragments of the active material when they break off, keeping them electrochemically accessible and allowing the material to be reused.

“It’s a tiny thing, this layer, but it’s important,” said study co-author Dr Paul Coxon from Cambridge’s Department of Materials Science and Metallurgy. “This gets us a long way through the bottleneck which is preventing the development of better batteries.”

A typical lithium-ion battery is made of three separate components: an anode (negative electrode), a cathode (positive electrode) and an electrolyte in the middle. ̽��ֱ��most common materials for the anode and cathode are graphite and lithium cobalt oxide respectively, which both have layered structures. Positively-charged lithium ions move back and forth from the cathode, through the electrolyte and into the anode.

̽��ֱ��crystal structure of the electrode materials determines how much energy can be squeezed into the battery. For example, due to the atomic structure of carbon, each carbon atom can take on six lithium ions, limiting the maximum capacity of the battery.

Sulphur and lithium react differently, via a multi-electron transfer mechanism meaning that elemental sulphur can offer a much higher theoretical capacity, resulting in a lithium-sulphur battery with much higher energy density. However, when the battery discharges, the lithium and sulphur interact and the ring-like sulphur molecules transform into chain-like structures, known as a poly-sulphides. As the battery undergoes several charge-discharge cycles, bits of the poly-sulphide can go into the electrolyte, so that over time the battery gradually loses active material.

̽��ֱ��Cambridge researchers have created a functional layer which lies on top of the cathode and fixes the active material to a conductive framework so the active material can be reused. ̽��ֱ��layer is made up of tiny, one-dimensional zinc oxide nanowires grown on a scaffold. ̽��ֱ��concept was trialled using commercially-available nickel foam for support. After successful results, the foam was replaced by a lightweight carbon fibre mat to reduce the battery’s overall weight.

“Changing from stiff nickel foam to flexible carbon fibre mat makes the layer mimic the way small intestine works even further,” said study co-author Dr Yingjun Liu.

This functional layer, like the intestinal villi it resembles, has a very high surface area. ̽��ֱ��material has a very strong chemical bond with the poly-sulphides, allowing the active material to be used for longer, greatly increasing the lifespan of the battery.

“This is the first time a chemically functional layer with a well-organised nano-architecture has been proposed to trap and reuse the dissolved active materials during battery charging and discharging,” said the study’s lead author Teng Zhao, a PhD student from the Department of Materials Science & Metallurgy. “By taking our inspiration from the natural world, we were able to come up with a solution that we hope will accelerate the development of next-generation batteries.”

For the time being, the device is a proof of principle, so commercially-available lithium-sulphur batteries are still some years away. Additionally, while the number of times the battery can be charged and discharged has been improved, it is still not able to go through as many charge cycles as a lithium-ion battery. However, since a lithium-sulphur battery does not need to be charged as often as a lithium-ion battery, it may be the case that the increase in energy density cancels out the lower total number of charge-discharge cycles.

“This is a way of getting around one of those awkward little problems that affects all of us,” said Coxon. “We’re all tied in to our electronic devices – ultimately, we’re just trying to make those devices work better, hopefully making our lives a little bit nicer.”

Reference:
Teng Zhao et al. ‘Advanced Lithium-Sulfur Batteries Enabled by a Bio-Inspired Polysulfide Adsorptive Brush.’ Advanced Functional Materials (2016). DOI: 10.1002/adfm.201604069

A new prototype of a lithium-sulphur battery – which could have five times the energy density of a typical lithium-ion battery – overcomes one of the key hurdles preventing their commercial development by mimicking the structure of the cells which allow us to absorb nutrients.

This gets us a long way through the bottleneck which is preventing the development of better batteries.

Paul Coxon

Teng Zhao

Computer visualisation of villi-like battery material

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Winners announced in the inaugural Vice-Chancellor’s Impact Awards and Public Engagement with Research Awards

jeh98 — Tue, 21 Jun 2016 09:58:54 +0000

On Monday 20 June, the Vice-Chancellor and Pro Vice-Chancellor for Research presented two sets of inaugural awards; the Impact Awards run by the Research Strategy Office, and the Public Engagement with Research Awards run by the Public Engagement team in the Office of External Affairs and Communications.

Research at the ̽��ֱ�� of Cambridge has had profound effects on society – it is a formal part of the ̽��ֱ��’s mission.

̽��ֱ��Vice-Chancellor’s Impact Awards have been established to recognise and reward those whose research has led to excellent impact beyond academia, whether on the economy, society, culture, public policy or services, health, the environment or quality of life.

In this, its inaugural year, there were 71 nominations across all Schools. Nominations were initially judged by School, with one overall best entry selected by external advisor Schlumberger. A prize of £1,000 was awarded to the best impact in each School, with the prize for the overall winner increased to £2,000.

̽��ֱ��winners were announced at an award ceremony on 20 June 2016, hosted by Professor Sir Leszek Borysiewicz. These winners, although very diverse, illustrate only a small part of the wide range of impact that Cambridge's research has had.

This year’s winners were:

Dr Mari Jones (Faculty of Modern and Medieval Languages)

Norman French has been spoken in Jersey for over 1,000 years. Today, however, this language (Jèrriais to its speakers) is obsolescent: spoken by some 1% of the population. ̽��ֱ��research of Mari Jones has sought to preserve Jèrriais and has helped raise the profile of the language within Jersey and beyond, with impacts on local and national media, language policy and education, and cultural identity and development.

Dr Gilly Carr (Department of Archaeology and Anthropology)

̽��ֱ��Channel Islands have long had great difficulty in coming to terms with the darker side of the German occupation. ̽��ֱ��aim of Gilly Carr’s research is to increase awareness of Channel Islander victims of Nazi persecution through creation of a plural ‘heritage landscape’ and via education. ̽��ֱ��creation of this heritage is a major achievement and will be of significant impact for the Channel Islands.

Professor Steve Jackson (Wellcome Trust/CRUK Gurdon Institute)

Olaparib is an innovative targeted therapy for cancer developed by Steve Jackson. In 2014 Olaparib was licensed for the treatment of advanced ovarian cancer by the US Food and Drug Administration and the European Medicines Agency. ̽��ֱ��following year, NICE made the drug available on the NHS in England for specific ovarian cancer patients. 2015 saw promising findings from a clinical trial in prostate cancer and Olaparib received Breakthrough Therapy Designation earlier this year. Olaparib is currently in clinical trials for a wide range of other cancer types.

Professor John Clarkson and Dr Nathan Crilly (Department of Engineering)

It is normal to be different. ̽��ֱ��demographics of the world are changing, with longer life expectancies and a reduced birth rate resulting in an increased proportion of older people. Yet with increasing age comes a general decline in capability, challenging the way people are able to interact with the ‘designed’ world around them. ̽��ֱ��Cambridge Engineering Design Centre has worked with the Royal College of Art to address this ‘design challenge’. They developed a design toolkit and realised what was by now obvious, that inclusive design was simply better design.

Dr Nita Forouhi and Dr Fumiaki Imamura (MRC Epidemiology Unit)

Identifying modifiable risk factors is an important step in helping reduce the health burden of poor diet. Forouhi and Imamura have advanced our understanding of the health impacts of sugars, fats and foods, through both scale and depth of investigation of self-reported information and nutritional biomarkers. They have engaged at an international level with policy and guidance bodies, and have used the media to improve public understanding with the potential for a direct impact on people’s health.

In 2015, the ̽��ֱ�� of Cambridge received a one-year £65k Catalyst Seed Fund grant from Research Councils UK to embed high quality public engagement with research and bring about culture change at an institutional level.

̽��ֱ��Public Engagement with Research Awards were set up to recognise and reward those who undertake quality engagement with research. 69 nominations were received from across all Schools.

This year’s winners were:

Dr Becky Inkster (Department of Psychiatry)

Dr Inkster’s work work explores the intersection of art and science through the prism of mental health research. Dr Inkster has successfully collaborated with ̽��ֱ��Scarabeus Theatre in a performance called Depths of My Mind and founded the website HipHopPsych, showcasing the latest psychiatry research through hip hop lyrics. Her approach has allowed her to engage with hard-to-reach teenage audiences, encouraging them to reflect on their own mental health. Beyond this work she has explored the use of social media to diagnose mental illness, and has gathered patient perspectives on ethics, privacy and data sharing in preparation for research publication.

Dr Paolo Bombelli (Department of Biochemistry)

Dr Bombelli’s research looks to utilise the photosynthetic chemistry of plants to create biophotovoltaic devices, a sustainable source of solar power. For over five years, he has been taking his research out of the lab to science festivals, schools and design fairs; tailoring his approach to a wider variety of audiences. Through his engagement, he has reached thousands of people, in multiple countries, and is currently developing an educational toolkit to further engage school students with advances in biophotovoltaic technology. Dr Bombelli’s public engagement work has also advanced his research, namely through a transition from using algae to moss in live demonstrations.

Dr Ruth Armstrong and Dr Amy Ludlow (Institute of Criminology and Faculty of Law)

Dr Armstrong and Dr Ludlow have collaborated on a research project addressing the delivery of education in the prison sector. Their project, Learning Together, pioneered a new approach to prison education where the end-users, the prisoners, are directly engaged with the design, delivery and evaluation of the research intervention. Adopting this shared dialogue approach has yielded positive results in terms of prisoners’ learning outcomes and has gathered praise from prison staff and government policy makers. Through continued engagement and partnership working, Armstrong and Ludlow have managed to expand their initiative across a broad range of sites and institutional contexts.

Dr Hazel Wilkinson (Department of English)

Dr Wilkinson is investigating the history of reading and writing habits in the eighteenth century. In collaboration with Dr Will Bowers at the ̽��ֱ�� of Oxford, she has developed an online public platform, journallists.org, which allows readers to engage with installments of periodicals, diaries, letters, and novels, on the anniversaries of the day on which they were originally published, written, or set. Her approach has allowed members of the public to actively participate in research. She has also inspired thousands of readers to engage with under-read eighteenth and nineteenth century texts, often for the very first time.

Dr Paul Coxon (Department of Materials Science and Metallurgy)

Over the last ten years Dr Coxon has endeavored to engage with audiences often overlooked by traditional public engagement channels. He has given talks in venues as varied as bingo halls, working men’s social clubs and steam fairs to showcase his passion for solar research, steering clear of the “flashes and bangs” approach often associated with Chemistry. He has also designed a Fruit Solar Cell Starter Kit, used in fifty low-income catchment schools across the UK.

Mr Ian Hosking and Mr Bill Nicholl (Department of Engineering and Faculty of Education)

Ian Hosking and Bill Nicholl are cofounders of Designing Our Tomorrow, a platform for transforming D&T education in schools. Their public engagement initiative began in 2009 and brought together research around inclusive design and creativity in education. Through production of their DOT box, Hosking and Nicholl have taken active research questions into the classroom and given students control of designing technological solutions. Engagement with teachers, students and policymakers is integral to the success of their initiative and has resulted in engineering design being included in the national curriculum and GCSE qualifications.

Researchers from across the ̽��ֱ�� have been recognised for the impact of their work on society, and engagement with research in the inaugural Vice-Chancellor’s Impact Awards and Public Engagement with Research Awards.

̽��ֱ�� of Cambridge

Dr Ruth Armstrong and Dr Amy Ludlow receive their award from the Vice-Chancellor, Professor Sir Leszek Borysiewicz

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Opinion: Harder than diamond: have scientists really found something tougher than nature’s invincible material?

Anonymous — Tue, 19 Jan 2016 14:00:25 +0000

Ask most people what the hardest material on Earth is and they will probably answer “diamond”. Its name comes from the Greek word ἀδάμας (adámas) meaning “unbreakable” or “invincible” and is from where we get the word “adamant”. Diamond’s hardness gives it incredible cutting abilities that – along with its beauty – have kept it in high demand for thousands of years.

Modern scientists have spent decades looking for cheaper, harder and more practical alternatives and every few years the news heralds the creation of a new “world’s hardest material”. But are any of these challengers really up to scratch?

Despite its unique allure, diamond is simply a special form, or “allotrope”, of carbon. There are several allotropes in the carbon family including carbon nanotubes, amorphous carbon, diamond and graphite. All are made up of carbon atoms, but the types of atomic bonds between them differ which gives rise to different material structures and properties.

̽��ֱ��outermost shell of each carbon atom has four electrons. In diamond, these electrons are shared with four other carbon atoms to form very strong chemical bonds resulting in an extremely rigid tetrahedral crystal. It is this simple, tightly-bonded arrangement that makes diamond one of the hardest substances on Earth.

How hard?

Vickers test anvil. R Tanaka, CC BY

Hardness is an important property of materials and often determines what they can be used for, but it is also quite difficult to define. For minerals, scratch hardness is a measure of how resistant it is to being scratched by another mineral.

There are several ways of measuring hardness but typically an instrument is used to make a dent in the material’s surface. ̽��ֱ��ratio between the surface area of the indentation and the force used to make it produces a hardness value. ̽��ֱ��harder the material, the larger the value. ̽��ֱ��Vickers hardness test uses a square-based pyramid diamond tip to make the indent.

Mild steel has a Vickers hardness value of around 9 GPa while diamond has a Vickers hardness value of around 70 – 100 GPa. Diamond’s resistance against wear is legendary and today 70% of the world’s natural diamonds are found in wear-resistant coatings for tools used in cutting, drilling and grinding, or as additives to abrasives.

̽��ֱ��problem with diamond is that, while it may be very hard, it is also surprisingly unstable. When diamond is heated above 800℃ in air its chemical properties change, affecting its strength and enabling it to react with iron, which makes it unsuitable for machining steel.

These limits on its use have led to a growing focus on developing new, chemically-stable, superhard materials as a replacement. Better wear-resistant coatings allow industrial tools to last longer between replacing worn parts and reduce the need for potentially environmentally-hazardous coolants. Scientists have so far managed to come up with several potential rivals to diamond.

Boron nitride

Microscopic BN crystal. NIMSoffice/Wikimedia Commons

̽��ֱ��synthetic material boron nitride, first produced in 1957, is similar to carbon in that it has several allotropes. In its cubic form (c-BN) it shares the same crystalline structure as diamond, but instead of carbon atoms is made up of alternately-bonded atoms of boron and nitrogen. c-BN is chemically and thermally stable, and is commonly used today as a superhard machine tool coating in the automotive and aerospace industries.

But cubic boron nitride is still, at best, just the world’s second hardest material with a Vickers hardness of around 50 GPa. Its hexagonal form (w-BN) was initially reported to be even harder but these results were based upon theoretical simulations that predicted an indentation strength 18% higher than diamond. Unfortunately w-BN is extremely rare in nature and difficult to produce in sufficient quantities to properly test this claim by experiment.

Synthetic diamond

Synthetic diamond closeup. Instytut Fizyki Uniwersytet Kazimierza Wielkiego, CC BY

Synthetic diamond has also been around since the 1950s and is often reported to be harder than natural diamond because of its different crystal structure. It can be produced by applying high pressure and temperature to graphite to force its structure to rearrange into the tetrahedral diamond, but this is slow and expensive. Another method is to effectively build it up with carbon atoms taken from heated hydrocarbon gases but the types of substrate material you can use are limited.

Producing diamonds synthetically creates stones that are polycrystalline and made up of aggregates of much smaller crystallites or “grains” ranging from a few microns down to several nanometers in size. This contrasts with the large monocrystals of most natural diamonds used for jewellery. ̽��ֱ��smaller the grain size, the more grain boundaries and the harder the material. Recent research on some synthetic diamond has shown it to have a Vickers hardness of up to 200 GPa.

Q-carbon

Q-Carbon closeup. North Carolina State ̽��ֱ��

More recently, researchers at North Carolina State ̽��ֱ�� created what they described as a new form of carbon, distinct from other allotropes, and reported to be harder than diamond. This new form was made by heating non-crystalline carbon with a high-powered fast laser pulse to 3,700 °C then quickly cooling or “quenching” it – hence the name “Q-carbon” – to form micron-sized diamonds.

̽��ֱ��scientists found Q-carbon to be 60% harder than diamond-like carbon (a type of amorphous carbon with similar properties to diamond). This has led them to expect Q-carbon to be harder than diamond itself, although this still remains to be proven experimentally. Q-carbon also has the unusual properties of being magnetic and glowing when exposed to light. But so far it’s main use has been as an intermediate step in producing tiny synthetic diamond particles at room temperature and pressure. These nanodiamonds are too small for jewellery but ideal as a cheap coating material for cutting and polishing tools.

Paul Coxon, Postdoctoral research associate, ̽��ֱ�� of Cambridge

This article was originally published on ̽��ֱ��Conversation. Read the original article.

̽��ֱ��opinions expressed in this article are those of the individual author(s) and do not represent the views of the ̽��ֱ�� of Cambridge.

Paul Coxon (Department of Materials Science and Metallurgy) discusses the materials that have each been heralded as the new “world’s hardest material”.

Judy van der Velden

Diamonds

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Novel Thoughts #1: Paul Coxon on Jan Wahl's SOS Bobomobile

lw355 — Mon, 08 Jun 2015 14:11:30 +0000

As a child, Dr Paul Coxon from Cambridge’s Department of Materials Science and Metallurgy, was fascinated by the madcap inventions of the boy hero in Jan Wahl’s SOS Bobomobile (illustrated by Fernando Krahn) – and he still likes to tinker with his own inventions in the lab today.

Here he talks about this favourite book as part of ‘Novel Thoughts’, a series exploring the literary reading habits of eight Cambridge scientists. From illustrated children’s books to Thomas Hardy, from Star Wars to Middlemarch, we find out what fiction has meant to each of the scientists and peek inside the covers of the books that have played a major role in their lives.

‘Novel Thoughts’ was inspired by research at the ̽��ֱ�� of St Andrews by Dr Sarah Dillon (now a lecturer in the Faculty of English at Cambridge) who interviewed 20 scientists for the ‘What Scientists Read’ project. She found that reading fiction can help scientists to see the bigger picture and be reminded of the complex richness of human experience. Novels can show the real stories behind the science, or trigger a desire in a young reader to change lives through scientific discovery. They can open up new worlds, or encourage a different approach to familiar tasks.

View the whole series: Novel Thoughts: What Cambridge scientists read.

Read about Novel Thoughts.

Is there a novel that has inspired you? Let us know! #novelthoughts

New film series Novel Thoughts reveals the reading habits of eight Cambridge scientists and peeks inside the covers of the books that have played a major role in their lives. In the first film, Dr Paul Coxon talks about how Jan Wahl’s SOS Bobomobile inspired his own inventions in the lab.

Novel Thoughts #1: Paul Coxon on Jan Wahl's SOS Bobmobile

̽��ֱ�� of Cambridge, Nick Saffell

Paul Coxon

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Novel Thoughts: what Cambridge scientists read

Anonymous — Mon, 08 Jun 2015 12:00:45 +0000

We may think that scientists inhabit a precisely focused world, far away from the messy realm of stories and the imagination, but a new film series, Novel Thoughts, from the ̽��ֱ�� of Cambridge shows that there is a bridge between the two.

Reading fiction helps scientists to see the bigger picture and be reminded of the complex richness of human experience. Novels can show the real human stories behind the science, or trigger a desire in a young reader to change lives through scientific discovery. They can open up new worlds, or encourage a different approach to familiar tasks.

For psychologist Dr Amy Milton, reading Requiem for a Dream by Hubert Selby during her PhD had a profound effect on her work. Its bleak portrayal of the downward spiral into addiction spurred her on to complete her thesis on cocaine addiction and to deepen her research into preventing relapse.

“ ̽��ֱ��book gave me a real insight into what it’s like for individuals living with addiction. It summed up how addiction, and the consequences of it, has not always been taken seriously as a disease by psychiatry,” she said.

As a teenager, Professor Carol Brayne’s love of Charles Dickens and George Eliot opened her eyes to a world in which social inequality had a powerful impact on people’s health and wellbeing. She vowed to become a doctor, and is now a leading figure in public health research at Cambridge. Her voracious reading as a young adult helped her understand the importance of seeing the bigger picture, and of finding health interventions that take account of the complexities of people’s lives.

For some, a book came along at just the right time. Professor Clare Bryant, of the Department of Zoology, read A S Byatt’s Possession at a crucial point in her early career. Its page-turning portrayal of two historians racing to uncover hidden truths reminded her of the excitement of scientific discovery, and persuaded her not to turn her back on her own research career.

Books can have a resonance throughout a scientific lifetime. Dr Juliet Foster can see that the themes explored in ̽��ֱ��Madness of a Seduced Woman by Susan Fromberg Schaeffer, which she read as a PhD student, still have echoes in her current social psychology research into public understandings of mental illness.

Dr Sarah Dillon, now in the Faculty of English at Cambridge, was the first to explore some of these ideas in a project she developed at the ̽��ֱ�� of St Andrews. Much has been written about science’s influence on literature – from Frankenstein to the futuristic worlds of science fiction – but she wanted to find out if the influence happened in the other direction. Did literature have an impact on the world of science?

Dillon joined forces with social scientist Christine Knight, and astronomer turned creative writer Pippa Goldschmidt to investigate What Scientists Read.

“What we found was that reading literature and ‘non-science’ books did have an influence on their work in quite surprising ways,” said Dillon. “There were lots of examples of scientists being more open to qualitative research methodologies because of valuing the knowledge that literature, even though it’s not ‘true’, gives you.”

̽��ֱ��Novel Thoughts film series begins on 8 June with physicist Dr Paul Coxon sharing his childhood reading about the quirky adventures of a boy inventor in the novel SOS Bobomobile. New films will be released every Monday and Friday until 3 July and scientists worldwide are being encouraged to tweet their own inspirational book using #novelthoughts.

Look out for:

Professor Clare Bryant from the Department of Veterinary Medicine discussing Possession by AS Byatt on 12 June.

Karen Yu from the Department of Engineering discussing Star Wars: From the Adventures of Luke Skywalker by George Lucas on 15 June.

Professor Simon Redfern from the Department of Earth Sciences discussing Jamila by Chinghiz Aitmatov on 19 June.

Dr Juliet Foster from the Department of Psychology discussing ̽��ֱ��Madness of a Seduced Woman by Susan Fromberg Schaeffer on 22 June.

Professor Carol Brayne, Director of the Cambridge Institute of Public Health, discussing Middlemarch by George Eliot on 29 June.

Dr Amy Milton from the Department of Psychology discussing Requiem for a Dream by Hubert Selby Junior on 3 July.

Literature and science may seem like opposite ends of the spectrum, but reading can have an impact on even the most scientific of brains. A new film series reveals the reading habits of seven Cambridge scientists and peeks inside the covers of the books that have played a major role in their lives.

̽��ֱ��book gave me a real insight into what it’s like for individuals living with addiction

Amy Milton

Novel Thoughts #1: Paul Coxon on Jan Wahl's SOS Bobmobile

̽��ֱ�� of Cambridge

Novel Thoughts

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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