Duke Research Blog

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

Category: Nanotech (Page 2 of 2)

Duke Labs Produce 2 Intel Talent Search Finalists

By Karl Leif Bates

Two North Carolina high school seniors who worked on their research projects in Duke University labs are among 40 students recently named finalists of the Intel Science Talent Search 2014.

Alec Arshavsky is a senior at East Chapel Hill  High School

Alec Arshavsky is a senior at East Chapel Hill High School

Alec Arshavsky, 17, of East Chapel Hill High School is being recognized for his project “Automatic Characterization of Donor Tissue for Corneal Transplantation Surgery.”

Arshavsky worked in the Duke lab of assistant professor of ophthalmology and biomedical engineering Sina Farsiu, developing an algorithm that automates the process of making precise measurements of a donor cornea for transplant. These measurements are currently being done laboriously by hand, and they ensure that the donor eye is healthy and will be compatible with a recipient’s anatomy and not change their vision too much.

Arshavsky spent two years working on his project, first learning the mathematical framework of image processing and then applying it to automate the process of analyzing corneal images from optical coherence tomography. His algorithm is currently being used in clinical trials. Arshavsky said he will pursue engineering in college but hasn’t chosen his school yet. Alec’s dad, Vadim Arshavsky, is a professor of ophthalmology and pharmacology at Duke.

Parth Thakker recently displayed a poster of his Duke research.

Parth Thakker recently displayed a poster of his Duke research.

Parth Thakker, 17, of the North Carolina School of Science and Mathematics in Durham, did his work, “Design, Assembly, and Optimization of Novel ZnxSeAgy Biocompatible Quantum Dot Sensitized Solar Cells” in the lab of Nico Hotz, an assistant professor of Mechanical Engineering and Materials Science at Duke.

The Hotz group has been working on quantum dots for solar collection that don’t rely on toxic cadmium and lead, making them safe for skin contact. Thakker, who’s from Charlotte, said there might be an application for a wearable device like Google Glass that would benefit from a little safe solar power.

Thakker worked on his project over three months last summer, making some winning suggestions about counter-electrodes and new ways of depositing quantum dots on a substrate, “but it’s very much a group project,” he said. Thakker, who is also the student body president at NCSSM, will be headed to Harvard in the Fall, possibly to study chemistry. (He also gives a pretty good TV interview.)

March 6-12, Arshavsky, Thakker and the other 38 finalists will travel to Washington, D.C. for a week-long event to pick the Intel Science Talent Search winners. They’ll undergo a rigorous judging process not only on their own work, but also covering general problem-solving and scientific knowledge. “They want to see how you think,” Arshavsky said. The students will also get a chance to interact with leading scientists and national leaders and will display their research for the public at the National Geographic Society.

The top 10 winners will be announced at a black-tie, invite-only gala awards ceremony at the National Building Museum on March 11, 2014.

Alec presenting his work at the 2013 Annual meeting of the Association for Research in Vision and Ophthalmology in Seattle.

Alec presenting his work at the 2013 Annual meeting of the Association for Research in Vision and Ophthalmology in Seattle.

The prestigious contest awards $630,000 in prizes this year, with the first-place winner receiving $100,000 from the Intel Foundation. Many past winners have gone on to achieve great things, including eight Nobel Prizes, two Fields Medals, five National Medals of Science, 11 MacArthur Foundation Fellowships and an Academy Award for Best Actress (that would be Natalie Portman).

The following week, Arshavsky will be off to Beijing to present his work again, this time one of four students selected as winners of the North Carolina International Science Challenge.

Reading between the lines of light

By Ashley Yeager

Harry Potter's invisibility cloak is not exactly what scientists have in mind for their light tricks. Credit: Warner Brothers.

The way we understand light is largely based on how we see it. To our eyes, light is like a stream of particles.

Scientists usually study these particle streams by measuring their wavelengths and how they interact with objects. But over the last decade, researchers have begun to realize that light particles can interact with objects within wavelengths too.

Now, scientists are looking inside wavelengths to control and manipulate light, which is transforming the traditional field of optics, according to Duke engineer David Smith and his colleagues.

They describe the changes to the field of optics in a review article appearing online Aug. 2 in Science, and they describe how, at a tenth or even a hundredth of the wavelength of visible light, the classic picture of how we see breaks down.

In this regime, streams of light particles can bend away from an object, essentially tricking the eye into thinking the object is not there. As a result, scientists can no longer think of light in terms of particle streams. Instead, they must think of it as a manipulation of electric and magnetic field lines.

Thinking of light this way, Smith and other scientists are beginning to understand how they can hide one object within another and even harvest energy. The new understanding “will be the design tool of choice” as scientists continue to play with the forces between electrically charged particles, the authors argue.


“Transformation Optics and Subwavelength Control of Light.” Pendry, J., et. al. 2012. Science 337: 549-552.
DOI: 10.1126/science.1220600

April 17 — Goo, Goop, Gack (and Snot!)

Gooey, goopy materials and a lecture about the wonders of snot are the stars of a family-friendly, hands-on evening of science on the Duke University campus  from 5–8 p.m. on Tuesday, April 17.


A quivering mass of cornstarch "oobleck." Image by Collin Mel Cunningham via Flickr

The event will be in the Fitzpatrick CIEMAS building on Duke’s West Campus. Public parking is available in the Bryan Center structure on Research Drive, near the Duke Chapel.

Faculty and students will share experiences with oobleck cornstarch polymers, origami that folds itself magically, and  ‘soft matter,’ which is a polite term for other kinds of goopy stuff.

The evening also features tours of facilities including the DiVE virtual reality simulator, and a guest lecture, “The Science of Snot,” by Dr. Richard Superfine of UNC-Chapel Hill’s physics department.

All this edutaining fun is sponsored by The Materials Research Science and Engineering Center of the Research Triangle, a collaborative effort of Triangle universities funded by the National Science Foundation.  It’s also a part of the state wide North Carolina Science Festival being held April 13-29.

For more information on this event and the NC Science Festival, go to: http://www.ncsciencefestival.org/event/duke-goo/

Catching the Space Bug

Prachiti Dalvi

Robert Satcher, MD, PhD –the first orthopedic oncologist to orbit the Earth –discussed his interest in telemedicine and telesurgery during a school of medicine seminar last month.

Growing up not to far from Duke in Denmark, South Carolina, Dr. Satcher developed a profound interest in science and chose to pursue chemical engineering at MIT. After graduating at the top of his class, he entered the MD/PhD program just across the river at Harvard Medical School and returned to MIT to complete his PhD in chemical engineering.

Then, he followed the more conventional route of interning in general surgery and spending his time as a resident at UCLA. Deciding to further specialize, Dr. Satcher proceeded with an orthopedic oncology fellowship at the University of Florida. For a short time period, Dr. Satcher was an assistant professor at Northwestern before he caught the space bug. Satcher successfully completed a rigorous application and interview process and was elected to begin space training at NASA.

Although his interests span chemical engineering and orthopedic oncology, he is particularly interested in bone mineralization, nanomaterials, and bone metastasis in cancer. At the MD Anderson Cancer Center he is exploring telesurgery and telemedicine. In November 2009, Dr. Satcher went into space as a mission specialist on Atlantis, spending more than 200 hours in space and engaging in more than twelve hours of spacewalk.

“Medical knowledge comes into play when people are going through adaptation in aerospace,” Satcher said. While in space, Satcher performed maintenance and conducted research on how the human body reacts in space. His own research interests resonated through when he was able to study how bone density and skeletal muscles are affected by zero gravity. Dr. Satcher likened walking in space while inspecting the station’s outside equipment to surgery: attention to precision is vital. To complete this task, he was able to use his surgical skills to navigate a robotic arm to scan the shuttle for damage.

Although space exploration comes with some dangers and difficulties, Satcher believes space exploration is important because there is a lot we still do not know. According to Dr. Robert Satcher, the common thread of curiosity for the unknown ties space exploration and medicine.

Particles of light overcome their lack of attraction

By Ashley Yeager

This waveguide shows an electric field moving from right to left. Credit: Setreset, Wikimedia Commons.

Electrons typically repulse each other. But sometimes they can actually attract each other and pair up, which is why superconductors exist. The particles that make up light, on the other hand, have no charge and rarely appeal to or repel one other.

Now, Duke theoretical physicist Harold Baranger and his collaborators think it’s possible to get these particles, called photons, to pair up, and stay that way, as they travel through space.

The new idea could help with the development of quantum communications, and possibly quantum computing in the future, Baranger says.

Particles of light do not have electric charge so they’ve got no attraction to the particles around them. That lack of attraction gives photons the ability to travel long distances without losing information, a good trait for building quantum networks.

But, the photons’ reserve has a drawback. It makes it more difficult for scientists to control each particle and retrieve the information it carries. To rein in the seemingly aloof photons, physicists have designed cavities that trap them and boost their contact with individual atoms.

In these cavities, the particles pass one by one through an atom in a phenomenon called a photon blockade. But, the cavities trap the photons for a really long time, so they pass through the cavities really slowly, which isn’t good for networking — especially in this age of instant information.

Using pencil and paper, Baranger, his student Huaixiu Zheng and colleague Daniel Gauthier, figured out that they could avoid the problems with the cavities if the photons instead went into a one-dimensional structure, called a waveguide, which also channels the photons past an atom one by one.

In the waveguide, a control atom acts as an intermediary between the incoming particles. The first photon passes through the atom and changes its state.

This diagram shows a photon blockade in a waveguide. Multiple photons (left, yellow) pass by the control atom in a one-by-one manner, ending with a train of single-photon pulses and empty pulses (gray). Courtesy of Harold Baranger, Duke.

The atom then interacts differently with the next photons, which ultimately causes the two particles of light to interact. What’s surprising, Baranger says, is that the photons are still bound to each other for a long time, even as they move away from the atom that paired them.

These bound states also end up producing a photon blockade much like in a cavity, but through a completely different mechanism, and the photons move a lot faster, he says.

The work, which appears online in Physical Review Letters, “paves the way” for experimentalists who want to try to build quantum networks without using cavities, Baranger says. He says experiments in this area may be done at Duke in the next few years.

Right now, he plans to work out what happens to the photons if more than one atom sits in the waveguide. The photons will be interacting in a lot of different places, and “one can imagine that there could even be a quantum phase transition, giving rise to some new quantum state,” he says. “But, that’s just a hope at this point.”

CITATION: Cavity-Free Photon Blockade Induced by Many-Body Bound States. Zheng, H., Gauthier, D., and Baranger, H. Phys. Rev. Lett. 107, 223601 (2011).

DOI: 10.1103/PhysRevLett.107.223601

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