Duke Research Blog

Following the people and events that make up the research community at Duke.

Category: Computers/Technology (Page 1 of 11)

Game-Changing App Explores Conservation’s Future

In the first week of February, students, experts and conservationists from across the country were brought together for the second annual Duke Blueprint symposium. Focused around the theme of “Nature and Progress,” this conference hoped to harness the power of diversity and interdisciplinary collaboration to develop solutions to some of the world’s most pressing environmental challenges.

Scott Loarie spoke at Duke’s Mary Duke Biddle Trent Semans Center.

One of the most exciting parts of this symposium’s first night was without a doubt its all-star cast of keynote speakers. The experiences and advice each of these researchers had to offer were far too diverse for any single blog post to capture, but one particularly interesting presentation (full video below) was that of National Geographic fellow Scott Loarie—co-director of the game-changing iNaturalist app.

iNat, as Loarie explained, is a collaborative citizen scientist network with aspirations of developing a comprehensive mapping of all terrestrial life. Any time they go outside, users of this app can photograph and upload pictures of any wildlife they encounter. A network of scientists and experts from around the world then helps the users identify their finds, generating data points on an interactive, user-generated map of various species’ ranges.

Simple, right? Multiply that by 500,000 users worldwide, though, and it’s easy to see why researchers like Loarie are excited by the possibilities an app like this can offer. The software first went live in 2008, and since then its user base has roughly doubled each year. This has meant the generation of over 8 million data points of 150,000 different species, including one-third of all known vertebrate species and 40% of all known species of mammal. Every day, the app catalogues around 15 new species.

“We’re slowly ticking away at the tree of life,” Loarie said.

Through iNaturalist, researchers are able to analyze and connect to data in ways never before thought possible. Changes to environments and species’ distributions can be observed or modeled in real time and with unheard-of collaborative opportunities.

To demonstrate the power of this connectedness, Loarie recalled one instance of a citizen scientist in Vietnam who took a picture of a snail. This species had never been captured, never been photographed, hadn’t been observed in over a century. One of iNat’s users recognized it anyway. How? He’d seen it in one of the journals from Captain James Cook’s 18th-century voyage to circumnavigate the globe.

It’s this kind of interconnectivity that demonstrates not just the potential of apps like iNaturalist, but also the power of collaboration and the possibilities symposia like Duke Blueprint offer. Bridging gaps, tearing down boundaries, building up bonds—these are the heart of conservationism’s future. Nature and Progress, working together, pulling us forward into a brighter world.

Post by Daniel Egitto

 

 

“I Heart Tech Fair” Showcases Cutting-Edge VR and More

Duke’s tech game is stronger than you might think.

OIT held an “I Love Tech Fair” in the Technology Engagement Center / Co-Lab on Feb. 6 that was open to anyone to come check out things like 3D printers and augmented reality, while munching on some Chick-fil-a and cookies. There was a raffle for some sweet prizes, too.

I got a full demonstration of the 3D printing process—it’s so easy! It requires some really expensive software called Fusion, but thankfully Duke is awesome and students can get it for free. You can make some killer stuff 3D printing, the technology is so advanced now. I’ve seen all kinds of things: models of my friend’s head, a doorstop made out of someone’s name … one guy even made a working ukulele apparently!

One of the cooler things at the fair was Augmented Reality books. These books look like ordinary picture books, but looking at a page through your phone’s camera, the image suddenly comes to life in 3D with tons of detail and color, seemingly floating above the book! All you have to do is download an app and get the right book. Augmented reality is only getting better as time goes on and will soon be a primary tool in education and gaming, which is why Duke Digital Initiative (DDI) wanted to show it off.

By far my favorite exhibit at the tech fair was  virtual reality. Throw on a headset and some bulky goggles, grab a controller in each hand, and suddenly you’re in another world. The guy running the station, Mark McGill, had actually hand-built the machine that ran it all. Very impressive guy. He told me the machine is the most expensive and important part, since it accounts for how smooth the immersion is. The smoother the immersion, the more realistic the experience. And boy, was it smooth. A couple years ago I experienced virtual reality at my high school and thought it was cool (I did get a little nauseous), but after Mark set me up with the “HTC Vive” connected to his sophisticated machine, it blew me away (with no nausea, too).

I smiled the whole time playing “Super Hot,” where I killed incoming waves of people in slow motion with ninja stars, guns, and rocks. Mark had tons of other games too, all downloaded from Steam, for both entertainment and educational purposes. One called “Organon” lets you examine human anatomy inside and out, and you can even upload your own MRIs. There’s an unbelievable amount of possibilities VR offers. You could conquer your fear of public speaking by being simulated in front of a crowd, or realistically tour “the VR Museum of Fine Art.” Games like these just aren’t the same were you to play them on, say, an Xbox, because it simply doesn’t have that key factor of feeling like you’re there. In Fallout 4, your heart pounds fast in your chest as you blast away Feral Ghouls and Super Mutants right in front of you. But in reality, you’re just standing in a green room with stupid looking goggles on. Awesome!

There’s another place on campus — the Bolt VR in Edens residence hall — that also has a cutting-edge VR setup going. Mark explained to me that Duke wants people to get experience with VR, as it will soon be a huge part of our lives. Having exposure now could give Duke graduates a very valuable head start in their career (while also making Duke look good). Plus, it’s nice to have on campus for offering students a fun break from all the hard work we put in.

If you’re bummed you missed out, or even if you don’t “love tech,” I recommend checking out the Tech Fair next time — February 13, from 6-8pm. See you there.

Post By Will Sheehan

Will Sheehan

Researchers Get Superman’s X-ray Vision

X-ray vision just got cooler. A technique developed in recent years boosts researchers’ ability to see through the body and capture high-resolution images of animals inside and out.

This special type of 3-D scanning reveals not only bones, teeth and other hard tissues, but also muscles, blood vessels and other soft structures that are difficult to see using conventional X-ray techniques.

Researchers have been using the method, called diceCT, to visualize the internal anatomy of dozens of different species at Duke’s Shared Materials Instrumentation Facility (SMIF).

There, the specimens are stained with an iodine solution that helps soft tissues absorb X-rays, then placed in a micro-CT scanner, which takes thousands of X-ray images from different angles while the specimen spins around. A computer then stitches the scans into digital cross sections and stacks them, like slices of bread, to create a virtual 3-D model that can be rotated, dissected and measured as if by hand.

Here’s a look at some of the images they’ve taken:

See-through shrimp

If you get flushed after a workout, you’re not alone — the Caribbean anemone shrimp does too.

Recent Duke Ph.D. Laura Bagge was scuba diving off the coast of Belize when she noticed the transparent shrimp Ancylomenes pedersoni turn from clear to cloudy after rapidly flipping its tail.

To find out why exercise changes the shrimp’s complexion, Bagge and Duke professor Sönke Johnsen and colleagues compared their internal anatomy before and after physical exertion using diceCT.

In the shrimp cross sections in this video, blood vessels are colored blue-green, and muscle is orange-red. The researchers found that more blood flowed to the tail after exercise, presumably to deliver more oxygen-rich blood to working muscles. The increased blood flow between muscle fibers causes light to scatter or bounce in different directions, which is why the normally see-through shrimp lose their transparency.

Peer inside the leg of a mouse

Duke cardiologist Christopher Kontos, M.D., and MD/PhD student Hasan Abbas have been using the technique to visualize the inside of a mouse’s leg.

The researchers hope the images will shed light on changes in blood vessels in people, particularly those with peripheral artery disease, in which plaque buildup in the arteries reduces blood flow to the extremities such as the legs and feet.

The micro-CT scanner at Duke’s Shared Materials Instrumentation Facility made it possible for Abbas and Kontos to see structures as small as 13 microns, or a fraction of the width of a human hair, including muscle fibers and even small arteries and veins in 3-D.

Take a tour through a tree shrew

DiceCT imaging allows Heather Kristjanson at the Johns Hopkins School of Medicine to digitally dissect the chewing muscles of animals such as this tree shrew, a small mammal from Southeast Asia that looks like a cross between a mouse and a squirrel. By virtually zooming in and measuring muscle volume and the length of muscle fibers, she hopes to see how strong they were. Studying such clues in modern mammals helps Kristjanson and colleagues reconstruct similar features in the earliest primates that lived millions of years ago.

Try it for yourself

Students and instructors who are interested in trying the technique in their research are eligible to apply for vouchers to cover SMIF fees. People at Duke University and elsewhere are encouraged to apply. For more information visit https://smif.pratt.duke.edu/Funding_Opportunities, or contact Dr. Mark Walters, Director of SMIF, via email at mark.walters@duke.edu.

Located on Duke’s West Campus in the Fitzpatrick Building, the SMIF is a shared use facility available to Duke researchers and educators as well as external users from other universities, government laboratories or industry through a partnership called the Research Triangle Nanotechnology Network. For more info visit http://smif.pratt.duke.edu/.

Post by Robin Smith, News and Communications

Post by Robin Smith, News and Communications

Farewell, Electrons: Future Electronics May Ride on New Three-in-One Particle

“Trion” may sound like the name of one of the theoretical particles blamed for mucking up operations aboard the Starship Enterprise.

But believe it or not, trions are real — and they may soon play a key role in electronic devices. Duke researchers have for the first time pinned down some of the behaviors of these one-of-a-kind particles, a first step towards putting them to work in electronics.

A carbon nanotube, shaped like a rod, is wrapped in a helical coating of polymer

Three-in-one particles called trions — carrying charge, energy and spin — zoom through special polymer-wrapped carbon nanotubes at room temperature. Credit: Yusong Bai.

Trions are what scientists call “quasiparticles,” bundles of energy, electric charge and spin that zoom around inside semiconductors.

“Trions display unique properties that you won’t be able to find in conventional particles like electrons, holes (positive charges) and excitons (electron-hole pairs that are formed when light interacts with certain materials),” said Yusong Bai, a postdoctoral scholar in the chemistry department at Duke. “Because of their unique properties, trions could be used in new electronics such as photovoltaics, photodetectors, or in spintronics.”

Usually these properties – energy, charge and spin – are carried by separate particles. For example, excitons carry the light energy that powers solar cells, and electrons or holes carry the electric charge that drives electronic devices. But trions are essentially three-in-one particles, combining these elements together into a single entity – hence the “tri” in trion.

A diagram of how a trion is formed in carbon nanotubes.

A trion is born when a particle called a polaron (top) marries an exciton (middle). Credit: Yusong Bai.

“A trion is this hybrid that involves a charge marrying an exciton to become a uniquely distinct particle,” said Michael Therien, the William R. Kenan, Jr. Professor of Chemistry at Duke. “And the reason why people are excited about trions is because they are a new way to manipulate spin, charge, and the energy of absorbed light, all simultaneously.”

Until recently, scientists hadn’t given trions much attention because they could only be found in semiconductors at extremely low temperatures – around 2 Kelvin, or -271 Celcius. A few years ago, researchers observed trions in carbon nanotubes at room temperature, opening up the potential to use them in real electronic devices.

Bai used a laser probing technique to study how trions behave in carefully engineered and highly uniform carbon nanotubes. He examined basic properties including how they are formed, how fast they move and how long they live.

He was surprised to find that under certain conditions, these unusual particles were actually quite easy to create and control.

“We found these particles are very stable in materials like carbon nanotubes, which can be used in a new generation of electronics,” Bai said. “This study is the first step in understanding how we might take advantage of their unique properties.”

The team published their results Jan. 8 in the Proceedings of the National Academy of Sciences.

Dynamics of charged excitons in electronically and morphologically homogeneous single-walled carbon nanotubes,” Yusong Bai, Jean-Hubert Olivier, George Bullard, Chaoren Liu and Michael J. Therien. Proceedings of the National Academy of Sciences, Jan. 8, 2018 (online) DOI: 10.1073/pnas.1712971115

Post by Kara Manke

David Carlson: Engineering and Machine Learning for Better Medicine

How can we even begin to understand the human brain?  Can we predict the way people will respond to stress by looking at their brains?  Is it possible, even, to predict depression based on observations of the brain?

These answers will have to come from sets of data, too big for human minds to work with on our own. We need mechanical minds for this task.

Machine learning algorithms can analyze this data much faster than a human could, finding patterns in the data that could take a team of researchers far longer to discover. It’s just like how we can travel so much faster by car or by plane than we could ever walk without the help of technology.

David Carlson Duke

David Carlson in his Duke office.

I had the opportunity to speak to David Carlson, an assistant professor of Civil and Environmental Engineering with a dual appointment at the Department of Biostatistics and Bioinformatics at Duke University.  Through machine learning algorithms, Carlson is connecting researchers across campus, from doctors to statisticians to engineers, creating a truly interdisciplinary research environment around these tools.

Carlson specializes in explainable machine learning: algorithms with inner workings comprehensible by humans. Most deep machine learning today exists in a “black box” — the decisions made by the algorithm are hidden behind layers of reasoning that give it incredible predictive power but make it hard for researchers to understand the “why” and the “how” behind the results. The transparent algorithms used by Carlson offer a way to capture some of the predictive power of machine learning without sacrificing our understanding of what they’re doing.

In his most recent research, Carlson collaborated with Dr. Kafui Dzirasa, associate professor of psychiatry and behavioral sciences and assistant professor in neurobiology and neurosurgery, on the effects of stress on the brains of mice, trying to understand the underlying causes of depression.

“What’s happening in neuroscience is the amount of data we’re sorting through is growing rapidly, and it’s really beginning to outstrip our ability to use classical tools,” Carlson says. “A lot of these classical tools made a lot more sense when you had these small data sets, but now we’re talking about this canonically overused word, Big Data”

With machine learning algorithms, it’s easier than ever to find trends in these huge sets of data.  In his most recent study, Carlson and his fellow researchers could find patterns tied to stress and even to how susceptible a mouse was to depression. By continuing this project and looking at new ways to investigate the brain and check their results, Carlson hopes to help improve treatments for depression in the future.

In addition to his ongoing research into depression, Carlson has brought machine learning to a number of other collaborations with the medical center, including research into autism and patient care for diabetes. When there’s too much data for the old ways of data analysis, machine learning can step in, and Carlson sees potential in harnessing this growing technology to improve health and care in the medical field.

“What’s incredibly exciting is the opportunities at the intersection of engineering and medicine,” he said. “I think there’s a lot of opportunities to combine what’s happening in the engineering school and also what’s happening at the medical center to try to create ways of better treating people and coming up with better ways for making people healthier.”

Guest Post by Thomas Yang, a junior at North Carolina School of Math and Science.

Martin Brooke: Mentoring Students Toward an X Prize for Ocean Robotics

We know less about the ocean floor than the surface of the moon. As one of the most unexplored areas of the world, multiple companies have begun to incentivize ingenuity towards exploring the oceans. Among these organizations are the Gates Foundation, the National Academy of Sciences, and X Prize.

XPrize team at Duke

Martin Brooke, second from left, and the student team with their giant drone.

Martin Brooke, an Associate Professor of Electrical and Computer Engineering at Duke, is presently leading a group of students who are working on mapping the ocean floor in an efficient way for the X Prize challenge.

Brooke said “open ended problems where you don’t know what to do” inspire him to do research about ocean engineering and design.

Martin Brooke

Martin Brooke

Collaborating with professors at the Duke Marine Lab that “strap marine sensors on whales” was a simple lead-in to starting a class about ocean engineering a few years ago. His teaching philosophy includes presenting the students with problems that make them think, “we want to do this, but we have no idea how.”

Before working on a drone that drops sensor pods down into the ocean to map the ocean floor, Brooke and his students built a sensor that could be in the ocean for a month or more and take pH readings every five seconds for a previous X Prize challenge.

Addressing the issues that many fisheries faced, he told me that he met an oyster farmer in Seattle who wished that there were pH sensors in the bay because sometimes tides bring in “waves of high pH water into the sound and kill all of the oysters without warning.” Citing climate change as the cause for this rise in pH, Brooke explained how increased carbon dioxide in the air dissolves into the water and raises the acidity. Emphasizing how “there’s not enough data on it,” it’s clear that knowing more about our oceans is beneficial economically and ecologically.

Guest Post by Sofia Sanchez, a senior at North Carolina School of Math and Science

Generating Winning Sports Headlines

What if there were a scientific way to come up with the most interesting sports headlines? With the development of computational journalism, this could be possible very soon.

Dr. Jun Yang is a database and data-intensive computing researcher and professor of Computer Science at Duke. One of his latest projects is computational journalism, in which he and other computer science researchers are considering how they can contribute to journalism with new technological advances and the ever-increasing availability of data.

An exciting and very relevant part of his project is based on raw data from Duke men’s basketball games. With computational journalism, Yang and his team of researchers have been able to generate diverse player or team factoids using the statistics of the games.

Grayson Allen headed for the hoop.

Grayson Allen headed for the hoop.

An example factoid might be that, in the first 8 games of this season, Duke has won 100% of its games when Grayson Allen has scored over 20 points. While this fact is obvious, since Duke is undefeated so far this season, Yang’s programs will also be able to generate very obscure factoids about each and every player that could lead to unique and unprecedented headlines.

While these statistics relating player and team success can only imply correlation, and not necessarily causation, they definitely have potential to be eye-catching sports headlines.

Extracting factoids hasn’t been a particularly challenging part of the project, but developing heuristics to choose which factoids are the most relevant and usable has been more difficult.

Developing these heuristics so far has involved developing scoring criteria based on what is intuitively impressive to the researcher. Another possible measure of evaluating the strength of a factoid is ranking the types of headlines that are most viewed. Using this method, heuristics could, in theory, be based on past successes and less on one researcher’s human intuition.

Something else to consider is which types of factoids are more powerful. For example, what’s better: a bolder claim in a shorter period of time, or a less bold claim but over many games or even seasons?

The ideal of this project is to continue to analyze data from the Duke men’s basketball team, generate interesting factoids, and put them on a public website about 10-15 minutes after the game.

Looking forward, computational journalism has huge potential for Duke men’s basketball, sports in general, and even for generating other news factoids. Even further, computational journalism and its scientific methodology might lead to the ability to quickly fact-check political claims.

Right now, however, it is fascinating to know that computer science has the potential to touch our lives in some pretty unexpected ways. As our current men’s basketball beginning-of-season winning streak continues, who knows what unprecedented factoids Jun Yang and his team are coming up with.

By Nina Cervantes

Opportunities at the Intersection of Technology and Healthcare

What’d you do this Halloween?

I attended a talk on the intersection of technology and healthcare by Dr. Erich Huang, who is an assistant professor of Biostatistics & Bioinformatics and Assistant Dean for Biomedical Informatics. He’s also the new co-director of Duke Forge, a health data science research group.

This was not a conventional Halloween activity by any means, but I felt lucky to be exposed to this impactful research surrounded by views of the Duke forest in fall in Penn Pavilion at IBM-Duke Day.

Erich Huang

Erich Huang, M.D., PhD. is the co-director of Duke Forge, our new health data effort.

Dr. Huang began his talk with a statistic: only six out of 53 landmark cancer biology research papers are reproducible. This fact was shocking (and maybe a little bit scary?), considering  that these papers serve as the foundation for saving cancer patients’ lives. Dr. Huang said that it’s time to raise standards for cancer research.

What is his proposed solution? Using data provenance, which is essentially a historical record of data and its origins, when dealing with important biomedical data.

He mentioned Duke Data Service (DukeDS), which is an information technology service that features data provenance for scientific workflows. With DukeDS, researchers are able to share data with approved team members across campus or across the world.

Next, Dr. Huang demonstrated the power of data science in healthcare by describing an example patient. Mr. Smith is 63 years old with a history of heart attacks and diabetes. He has been having trouble sleeping and his feet have been red and puffy. Mr. Smith meets the criteria for heart failure and appropriate interventions, such as a heart pump and blood thinners.

A problem that many patients at risk of heart failure face is forgetting to take their blood thinners. Using Pillsy, a company that makes smart pill bottles with automatic tracking, we could record Mr. Smith’s medication taking and record this information on the blockchain, or by storing blocks of information that are linked together so that each block points to an older version of that information. This type of technology might allow for the recalculation of dosage so that Mr. Smith could take the appropriate amount after a missed dose of a blood thinner.

These uses of data science, and specifically blockchain and data provenance, show great opportunity at the intersection of technology and healthcare. Having access to secure and traceable data can lead to research being more reproducible and therefore reliable.

At the end of his presentation, Dr. Huang suggested as much collaboration in research between IBM and Duke as possible, especially in his field. Seeing that the Research Triangle Park location of IBM is the largest IBM development site in the world and is conveniently located to one of the best research universities in the nation, his suggestion makes complete sense.

By Nina Cervantes        

Global Health Research from Zika to Economics

Brazil, Kenya and China: this week, the sixth annual Global Health Research Showcase proved that Global Health majors truly represent global interests.

This past summer, Duke PhD student Tulika Singh explored complementary diagnosis techniques for Zika virus pregnant women in Vitoria, Brazil. Zika is difficult to diagnose “because the PCR-based test can only tell if you’ve had Zika virus within about ten days of the infection,” Singh said. “That’s a big problem for enrolling pregnant women into our study on Zika transmission and maternal immunity.”

To combat this issue, Singh and her thesis advisor Sallie Permar trained collaborators to use the whole virion ELISA (WVE) laboratory technique which may reveal if an individual has been exposed to Zika. ELISA detects Zika through testing for the antibodies that most likely would have been produced during a Zika infection. Singh’s work allows the research team to better assess whether women have been exposed to Zika virus during pregnancy, and will ultimately guide Zika vaccine design. 

Master of Science in Global Health candidate Carissa Novak examined why some HPV positive women in Western Kenya are not seeking preventive measures against cervical cancer. All the women diagnosed with HPV were referred to the Country Hospital but only “33 to 42 percent actually sought treatment” leading to Novak’s main research question, “Why did so few women seek treatment?” To answer this question, she sent out quantitative questionnaires to 100 women and then followed up by interviewing 20 of them. She surveyed and interviewed both women who had and had not sought treatment. Her results showed that transportation and cost hinder treatment acquirement and that the women who did seek treatment were often directed to by a health worker or actively trying to prevent cervical cancer. Novak believes that increasing women’s trust and understanding of the health care system will assist in improving the percentage who seek treatment.

In Kunshan, China, Brian Grasso evaluated the development of Kunshan’s health system in relation to its economic development. “Kunshan is now China’s richest county-level city and it used to be a small farm town…My main take away was that economic growth has strengthened Kunshan’s health systems while also creating new health challenges,” Grasso said. What are some of these new health challenges? Some of them include air pollution, increased stress in manufacturing jobs and more car accidents. Grasso determines that other developing health systems should learn from Kunshan that without proper regulations poor health can result in the midst of progress.

Post by Lydia Goff

Cheating Time to Watch Liquids do the Slow Dance

Colorful spheres simulating liquid molecules shift around inside a cube shape

The team’s new algorithm is able to simulate molecular configurations of supercooled liquids below the glass transition. The properties of these configurations are helping to solve a 70-year paradox about the entropy of glasses. Credit: Misaki Ozawa and Andrea Ninarello, Université de Montpellier.

If you could put on a pair of swimming goggles, shrink yourself down like a character from The Magic School Bus and take a deep dive inside a liquid, you would see a crowd of molecules all partying like it’s 1999.

All this frenetic wiggling makes it easy for molecules to rearrange themselves and for the liquid as a whole to change shape. But for supercooled liquids — liquids like honey that are cooled below their freezing point without crystallizing – the lower temperature slows down the dancing like Etta James’ “At Last.” Lower the temperature enough, and the slow-down can be so dramatic that it takes centuries or even millennia for the molecules to rearrange and the liquid to move.

Scientists can’t study processes that last longer than their careers. But Duke chemists and their Simons Foundation collaborators have found a way to cheat time, simulating the slow dance of deeply supercooled liquids. Along the way, they have found new physical properties of “aged” supercooled liquids and glasses.

A droplet rises above a surface of water

Credit: Ruben Alexander via Flickr.

To understand just how slow deeply supercooled liquids move, consider the world’s longest-running experiment, the University of Queensland’s Pitch Drop Experiment. A single drop of pitch forms every eight to thirteen years — and this pitch is moving faster than deeply supercooled liquids.

“Experimentally there is a limit to what you can observe, because even if you managed to do it over your entire career, that is still a maximum of 50 years,” said Patrick Charbonneau, an associate professor of chemistry and physics at Duke. “For many people that was considered a hard glass ceiling, beyond which you couldn’t study the behavior of supercooled liquids.”

Charbonneau, who is an expert on numerical simulations, said that using computers to simulate the behavior of supercooled liquids has even steeper time limitations. He estimates that, given the current rate of computer advancement, it would take 50 to 100 years before computers would be powerful enough for simulations to exceed experimental capabilities – and even then the simulations would take months.

To break this glass ceiling, the Charbonneau group collaborated with Ludovic Berthier and his team, who were developing an algorithm to bypass these time constraints. Rather than taking months or years to simulate how each molecule in a supercooled liquids jiggles around until the molecules rearrange, the algorithm picks individual molecules to swap places with each other, creating new molecular configurations.

This allows the team to explore new configurations that could take millennia to form naturally. These “deeply supercooled liquids and ultra-aged glasses” liquids are at a lower energy, and more stable, than any observed before.

“We were cheating time in the sense that we didn’t have to follow the dynamics of the system,” Charbonneau said. “We were able to simulate deeply supercooled liquids well beyond is possible in experiments, and it opened up a lot of possibilities.”

Two columns of blue and red spheres represent simulations of vapor-deposited glasses.

Glasses that are grown one layer at a time have a much different structure than bulk glasses. The team used their new algorithm to study how molecules in these glasses rearrange, and found that at low temperatures (right), only the molecules at the surface are mobile. The results may be used to design better types of glass for drug delivery or protective coatings. Credit: Elijah Flenner.

Last summer, the team used this technique to discover a new phase transition in low-temperature glasses. They recently published two additional studies, one of which sheds light on the “Kauzmann paradox,” a 70-year question about the entropy of supercooled liquids below the glass transition. The second explores the formation of vapor-deposited glasses, which have applications in drug delivery and protective coatings.

“Nature has only one way to equilibrate, by just following the molecular dynamics,” said Sho Yaida, a postdoctoral fellow in Charbonneau’s lab. “But the great thing about numerical simulations is you can tweak the algorithm to accelerate your experiment.”

Configurational entropy measurements in extremely supercooled liquids that break the glass ceiling.” Ludovic Berthier, Patrick Charbonneau, Daniele Coslovich, Andrea Ninarello, Misaki Ozawa and Sho Yaida. PNAS, Oct. 24, 2017. DOI: 10.1073/pnas.1706860114

The origin of ultrastability in vapor-deposited glasses.” Ludovic Berthier, Patrick Charbonneau, Elijah Flenner and Francesco Zamponi. PRL, Nov. 1, 2017. DOI: 10.1103/PhysRevLett.119.188002

Post by Kara Manke

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