Isha Dube

Isha Dube attended the University of Lucknow, in India, where she received a B.S. and an M.S. in Physics. She was drawn to Georgetown by Professor Paranjape’s work with Micro Electro-Mechanical Systems, or MEMS.
“I was doing a study on this for my Master’s,” Isha explains. “I wanted to continue in the same field.”

The one-year industrial internship was also part of Georgetown’s appeal, and when Isha entered the Ph.D. program in the fall of 2007, she decided to pursue the Industrial Leadership in Physics track.

Isha chose an internship at Procter & Gamble, in Cincinnati. She worked in the Micro Fluidics group studying about detergents and how well they dissolved in water. Most of her work was focused on studying the phase transitions taking place during the dissolution process of surfactants, which are the raw materials for making soaps. Although the topic is completely unrelated to her thesis research work at Georgetown, the experience was more than valuable.

“I will definitely cherish the experience of working in an industrial research environment,” Isha says. “Industrial research is very eye-opening.”

Isha returned to Georgetown after finishing her apprenticeship at Procter & Gamble and began thesis research under the guidance of Professor Paranjape and Professor Barbara.

Her research involves fabricating individual carbon nanotube (CNT) based field effect transistors (FETs), and studying their response towards various environmental gases, such as nitrogen dioxide, ammonia, and hydrogen.

She comments that the existing research has focused on empirically determining the response of CNTFETs towards various gases through a modification of the configuration of the CNTFET, such as using individual CNTs or networks of CNTs, using different metals for electrodes, and depositing nanoparticles of metal or polymer or oxide layers on the nanotube.

However, the possible mechanism of gas detection has not been researched as extensively. The intuitive and widely accepted explanation is that molecules bind to the surface of the nanotube and charge transfer occurs between the nanotube and the molecules. A second possibility is a change in the Schottky barrier at the interface between the nanotube and metal.

Prior experimental work by Prof. Barbara’s group has confirmed that the change in the Schottky barrier is the basis for gas detection, but a greater understanding of how ambient gases modify the Schottky barrier is still needed. Isha’s thesis research revolves around performing a systematic study on the interplay between the metal-nanotube junction and gases to establish the underlying detection mechanism of gas sensing in the CNTFETs.

Isha has a few more years to complete her thesis, and she’s still contemplating whether to pursue academia or the industrial route at this point. Both options have their own merits and demerits.

“If I get an opportunity to work in an industrial set-up, I will definitely consider it,” Isha says. “Although, working in academia gives you freedom of thought.”

Isha is active in a charity to support impoverished girls in India. She recently ran in the Baltimore Marathon to raise money for the charity. Isha also sings and plays the guitar. She has performed at the Library of Congress and the Gandhi Memorial Center, in Northwest D.C.

Kai He

The figure illustrates the discovery of a new signature of the Anderson localization transition: the critical exponents of the finite-size scaling of quantum correlations. This was in Kai's most recent publication, “Noise correlation scalings: Revisiting the quantum phase transition in incommensurate lattices with hard-core bosons,” published in the January 2012 edition of Physical Review A.

Kai He arrived at Georgetown in the fall of 2008, after receiving a B.S. from Nanjing University. He entered the Industrial Leadership in Physics program, and eventually joined the research group of Marcos Rigol, which focuses on strongly correlated quantum many-body systems.

The ILP program was an important factor in influencing Kai’s decision to attend Georgetown.

“It was creative that at that moment there was a program that tried to relate more to industry rather than just academia,” Kai says. “It’s the nature of the practical and industry-oriented program that appealed to me.”

After finishing his coursework, Kai completed an apprenticeship at the National Institute of Standards and Technology, which is located in Gaithersburg, Maryland. He was able to work with collaborators of Dr. Rigol’s research group and to continue the same type of research he had been doing at Georgetown. Kai’s time at NIST gave him the opportunity to conduct interactive and collaborative research in an environment he would not have experienced through ordinary thesis research.

Kai returned to Georgetown and began work on his thesis, examining the equilibrium and non-equilibrium properties of ultra-cold atoms on optical lattice.

“So far I have two publications on one-dimensional quantum gas problems,” he says.

His most recent publication, “Noise correlation scalings: Revisiting the quantum phase transition in incommensurate lattices with hard-core bosons,” appeared in Physical Review A in January 2012.

After completing his degree, Kai plans to work in a field where he can put his quantitative reasoning skills to use.

“I will try to look for a place where I can apply my computational skills,” he says. “I’m interested in fields that need data analysis, although not necessarily in physics.”

In his free time, Kai enjoys watching soccer games, especially when Arsenal is playing.

Richard Arevalo

When Rich Arevalo graduated from Georgetown in 2005, he knew that he wanted to go to graduate school for physics. He first attended City College of New York, but in 2007 he returned to Georgetown and joined the research groups of Dr. Dan Blair and Dr. Jeff Urbach.

Rich has always been interested in the traditional physics curriculum, so he chose to follow the standard Ph.D. track, rather than the Industrial Leadership in Physics track. After completing his coursework, he began work on his thesis. He now conducts research on the properties of biopolymer networks.

“I am investigating how stress propagates through a branched biopolymer network,” Rich says. “Our research group uses novel dynamics imaging technology to directly visualize the microscopic behavior of soft materials under precisely controlled shear. Consequently, we gain the insight necessary to explain the interesting macroscopic mechanical behavior of our soft materials on a more fundamental and unique level.”

Rich recently had an article published in Chaos: An Interdisciplinary Journal of Nonlinear Science. The article, entitled “Four-dimensional structural dynamics of sheared collagen networks,” was co-authored by Dr. Urbach and Dr. Blair.

After completing his degree, Rich plans to stay in the Northeast. He hopes to work for a security agency, possibly a defense contractor.

In his free time, Rich enjoys playing tennis, going to concerts, and playing the guitar.

The image above is from Rich’s article in Chaos. His own explanation of the research is below:

Soft biopolymer networks undergo substantial bulk stiffening and contraction when subject to shear strain. These nonlinear rheological signatures have been well-documented for a wide range of semiflexible and stiff biopolymers, but the underlying geometric fiber rearrangements have not been measured and the resulting propagation of stress through the microscopic network has not been experimentally assessed.

We apply precisely controlled shear strain to collagen gels adhered to thin elastic polyacrylamide gel substrates embedded with fluorescent microspheres while simultaneously imaging the three-dimensional networks with a coupled confocal-rheometer. We observe dramatic network realignment in the direction of shear driven by the buckling, rotation, and stretching of undulated constituent fibers and simultaneously measure stress inhomogeneities at the collagen-polyacrylamide interface.

With the addition of fluorescent tracer particles in the collagen network, we observe nonaffine network deformations strongly correlated with the concurrently measured bulk stiffening. These observations elucidate the physical mechanisms governing contraction, strain-stiffening, and our recent observation of the system-size dependence of the stiffening effect.

Tony Boyd

Tony Boyd graduated from Georgetown in May 2005, and enrolled in the physics graduate program the following fall. As a student in the Industrial Leadership in Physics program, he completed three semesters of coursework, followed by an off-site apprenticeship.

Tony took advantage of one of many of the opportunities in physics in the D.C. area, and completed an apprenticeship at the Army Research Lab, which is located just outside of D.C in Adelphi, Maryland. During the apprenticeship, Tony met people working in industry in the D.C. area and learned new laboratory techniques.

“It exposed me to a lot of techniques that are certainly becoming more important now,” Tony says. “I did a lot of clean room work.”

Tony returned to Georgetown to work on his thesis in the research group of Dr. Paola Barbara. His research focuses on the change in the conductance of carbon nanotubes when they are exposed to gas. This is an extension of the research Tony did as an undergraduate at Georgetown.

“I’m moving from a single nanotube to multiple nanotubes to see if that changes the gas sensing mechanism,” he says.

Tony was drawn to Georgetown by the ILP program’s business focus. He knew that he did not want to work in academia, yet he was still interested in pursuing a graduate degree in physics. Georgetown proved to be the ideal fit.

“It’s one of the few business-related programs out there,” he says.

Another plus was Georgetown’s location—Washington, DC is the place to be for someone who, like Tony, hopes to work for a government contractor.

Yanfei Yang

Yanfei Yang earned a B.S. in Applied Optics in 1999 at Sichuan University, in Chengdu, China, and began graduate studies at Georgetown in the fall of 2002.

As part of the Industrial Leadership in Physics curriculum, Yanfei spent a year working under the direction of Dr. Mark Covington at the Seagate Technologies Research Center in Pittsburgh, where she characterized the dynamical behavior of magnetization in nanopillar giant magnetoresistance devices [1]. These types of devices are used in the sensors that read data stored on hard drives, and the project was aimed at elucidating noise mechanisms that can adversely impact the performance of a hard disk drive recording system.

“Through the apprenticeship I gained hands-on experience with magnetism measurements in nanoscale devices, which enriched my background and knowledge in physics,” Yanfei says. She also developed a better understanding of the applied nature of research in a high-tech company.

After returning to Georgetown, Yanfei joined the research group of Professor Paola Barbara, participating in a NSF-funded project to explore possible superconductivity in carbon nanotubes. While her coursework at Georgetown had given her a good foundation in condensed matter physics, once she chose her research topic, Yanfei took advantage of the Washington Consortium of Universities' cross registration program to take an advanced course on superconductivity at the University of Maryland in order to gain more specialized knowledge relevant to her research.

Carbon nanotubes (CNT) have many surprising properties, including very high electronic and thermal conductivity, superior strength, stiffness, and toughness along with elasticity. Moreover, due to their high aspect ratio (hundreds micrometers in length vs. few nanometers in diameter), they are nearly ideal 1D ballistic conductors. Yanfei's dissertation research involved fabricating CNT field effect transistors and measuring their electrical properties as a function of temperature and field-induced doping. She found that a single nanotube in contact with normal metal electrodes may become superconducting below about 30 K [2,3].

After completing her thesis, entitled “Quantum Transport and Field Induced Superconductivity in Carbon Nanotubes.” Yanfei stayed on as a postdoctoral fellow in the research group of Professor Barbara. She is now a postdoctoral researcher based at NIST, working on a collaborative project between NIST and Georgetown. Reflecting on her graduate experience, Yanfei says “I am very grateful for the years learning and working in Professor Barbara's research group.”

When she’s not doing physics, Yanfei enjoys all kinds of outdoor and indoor activities such as hiking, traveling, tennis, ice skating, reading, and drawing.

References:

[1] M. Covington, Y. Yang, T. M. Crawford, N. J. Gokemeijer, and M. A. Seigler. Magnetization dynamics driven by spin momentum transfer (Invited Paper). Proc. SPIE 5843, 11 (2005).

[2] J. Zhang, A. Tselev, Y. Yang, K. Hatton, S. E. Shafranjuk and P. Barbara. Zero-bias anomaly and possible superconductivity in single-walled carbon nanotube. Phys. Rev. B 74, 155414 (2006).

[3] Y. Yang, G. Fedorov, J. Zhang, A. Tselev, S. E. Shafranjuk and P. Barbara. Search for superconductivity at van Hove singularities in carbon nanotubes (Invited Paper). Manuscript submitted to Superconductor Science and Technology.