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Posted on Sep 22, 2014

This Is What Science Looks Like At NC State: Sasha Ishmael

Editor’s note: This post was written by Sasha Ishmael, a postdoctoral researcher in materials science and engineering at NC State. The post is an entry in an ongoing series that we hope will highlight the diversity of researchers in science, technology, engineering and mathematics. The series is inspired by the This Is What A Scientist Looks Like site.

My name is Sasha, and I’m quietly admitting that I am afraid of the dark…Please don’t tell anyone. One of my most dreaded early memories as a child was being without electrical power. I grew up on a small island in the Caribbean, Trinidad and Tobago. Okay, I lived on Trinidad, and it’s actually two islands forming one country, but that’s a history lesson for another time.

As you can probably imagine, the electrical power grid of a developing country was not very reliable at that time. Frequent power outages caused moments in my life when I felt unfairly taken away from the things I loved to do. Reading by candle light was no fun, and there was no internet, allowing the opportunity for watching reruns of my favorite shows. This dark time was lost time, utterly and completely lost, and I thought I would never regain the light I craved.

Skipping to a few of the brighter memories from my childhood: My mother was the earliest person I can remember, who introduced me to science. She is a former high school biology teacher who also taught physics. From an early age, while taking walks in our garden in Trinidad, she taught me about all types of plants and flowers. Soon I could identify different parts of the flowers and even describe their specific functions.

Sasha Ishmael and her mother. Photo courtesy of Sasha Ishmael.

Sasha Ishmael and her mother. Photo courtesy of Sasha Ishmael.

Also in my extended family, spanning several generations, the common theme was the pursuit of knowledge. My love for technology was triggered by a cousin, who introduced me to the wonders of computers and programming. The first time he showed me a game, where the computer spoke to me, I spoke back to it but waited in vain for a response. A bit too forward thinking, since at the time voice recognition and processing did not exist.

Around the age of 15 I had to make a decision on what field of study to pursue. I decided to concentrate on physics, mathematics and biology, core areas that would eventually lead me to where and who I am today. After graduating from high school I opted for a field that felt challenging and exciting to me, electrical and computer engineering. Out of the many diverse areas in this field of study, I fell in love with the theory of electromagnetics. Little did I know that this love would shine even brighter, when I was introduced to the field of superconductivity.

We all know that normally metals are very good at carrying an electrical current. Superconductors are materials that, when cooled to very low temperatures, are in fact SUPER at carrying electrical currents and can ideally do so with zero losses in energy. Applications that use superconducting devices are in the areas of medicine for internal imaging of the body (MRI), in high energy physics like particle accelerators (Large Hadron Collider) and electrical power and energy devices that can generate, use and transmit electrical power.

Wait a minute…devices made with superconducting materials can help transfer electrical power with zero losses??? The idea of lossless power transmission was, to me, like finding the Holy Grail!! If this was the case why was it not being done everywhere? I soon learned that there were a challenging set of complex issues that were preventing widespread application. Challenge accepted! If I could help bring superconducting devices like electrical generators and power transmission lines to reality, no one would ever have to miss out on doing the things they love; feeling connected to the world and keeping the light of hope shining. I became dedicated to help.

Needless to say, from that point on, I was naturally propelled into an academic career that led me to complete my Ph.D. in electrical engineering and to the research I do today.

Currently, I am a postdoctoral research scientist in the Materials Science and Engineering Department at NC State. I work on research related to superconductivity with my mentor, Justin Schwartz. I am doing research related to the integration of materials into superconducting devices to make them viable solutions for more applications. Two of the topics of my research are fiber optic sensors for monitoring the health of superconducting magnets and ceramic nano-powders that can be used as thermally conductive electrical insulation for superconducting wires. My wish is that my research and contributions will help illuminate the path that makes superconducting devices a commonplace reality.

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Posted on Sep 15, 2014

Researchers Control Surface Tension to Manipulate Liquid Metals

Researchers from North Carolina State University have developed a technique for controlling the surface tension of liquid metals by applying very low voltages, opening the door to a new generation of reconfigurable electronic circuits, antennas and other technologies. The technique hinges on the fact that the oxide “skin” of the metal – which can be deposited or removed – acts as a surfactant, lowering the surface tension between the metal and the surrounding fluid.

The researchers used a liquid metal alloy of gallium and indium. In base, the bare alloy has a remarkably high surface tension of about 500 millinewtons (mN)/meter, which causes the metal to bead up into a spherical blob.

Liquid metals normally form a spherical shape due to their large surface tension.  By applying a small voltage to the metal in water, a surface oxide forms on the surface of the metal and lowers the surface tension.  Reversing the bias can remove the oxide and return the metal to a large surface tension.  These phenomena can be utilized to control the shape of the metal and get it to flow in and out of capillaries. Click to enlarge. Image credit: Mohammad Khan.

Liquid metals normally form a spherical shape due to their large surface tension. By applying a small voltage to the metal in water, a surface oxide forms on the surface of the metal and lowers the surface tension. Reversing the bias can remove the oxide and return the metal to a large surface tension. These phenomena can be utilized to control the shape of the metal and get it to flow in and out of capillaries. Click to enlarge. Image credit: Mohammad Khan.

“But we discovered that applying a small, positive charge – less than 1 volt – causes an electrochemical reaction that creates an oxide layer on the surface of the metal, dramatically lowering the surface tension from 500 mN/meter to around 2 mN/meter,” says Dr. Michael Dickey, an associate professor of chemical and biomolecular engineering at NC State and senior author of a paper describing the work. “This change allows the liquid metal to spread out like a pancake, due to gravity.”

The researchers also showed that the change in surface tension is reversible. If researchers flip the polarity of the charge from positive to negative, the oxide is eliminated and high surface tension is restored.  The surface tension can be tuned between these two extremes by varying the voltage in small steps.

“The resulting changes in surface tension are among the largest ever reported, which is remarkable considering it can be manipulated by less than one volt,” Dickey says. “We can use this technique to control the movement of liquid metals, allowing us to change the shape of antennas and complete or break circuits. It could also be used in microfluidic channels, MEMS, or photonic and optical devices. Many materials form surface oxides, so the work could extend beyond the liquid metals studied here.”

Dickey’s lab had previously demonstrated a technique for “3-D printing” liquid metals, which used the oxide layer formed in air to help the liquid metal retain its shape – the exact opposite of what the oxide layer does to the alloy in a basic solution.

“We think the oxide’s mechanical properties are different in a basic environment than they are in ambient air,” Dickey says.

The paper, “Giant and Switchable Surface Activity of Liquid Metal via Surface Oxidation,” will be published online in the Proceedings of the National Academy of Sciences during the week of September 15. Lead authors of the paper are Mohammad Rashed Khan and Collin Eaker, Ph.D. students at NC State. The paper was co-authored by Dr. Edmond Bowden, a professor of chemistry at NC State.

The research was supported by National Science Foundation (NSF) CAREER grant number CMMI-0954321 and the Research Triangle NSF Materials Research Science and Engineering Center on Programmable Soft Matter grant number DMR-1121107.

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Note to Editors: The study abstract follows.

“Giant and Switchable Surface Activity of Liquid Metal via Surface Oxidation”

Authors: Mohammad Rashed Khan, Collin B. Eaker, Edmond Bowden, and Michael D. Dickey, North Carolina State University

Published: Online the week of Sept. 15 in Proceedings of the National Academy of Sciences

DOI: 10.1073/pnas.1412227111

Abstract: We present a new method to control the interfacial tension of a liquid alloy of gallium via electrochemical deposition (or removal) of the oxide layer on its surface. In sharp contrast with conventional surfactants, this method provides unprecedented lowering of surface tension (?500 mJ/m2 to near zero) using very low voltage and the change is completely reversible. This dramatic change in the interfacial tension enables a variety of new electrohydrodynamic phenomena. The ability to manipulate the interfacial properties of the metal promises rich opportunities in shape-reconfigurable metallic components in electronic, electromagnetic, and microfluidic devices without the use of toxic mercury. This work suggests that the wetting properties of surface oxides—which are ubiquitous on most metals and semiconductors—are intrinsic ‘surfactants’. The inherent asymmetric nature of the surface coupled with the ability to actively manipulate its energetics are expected to have important applications in electrohydrodynamics, composites, and melt processing of oxide-forming materials.

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Posted on Sep 15, 2014

This Is What Science Looks Like At NC State: De Anna Beasley

Editor’s note: This post was written by De Anna Beasley, a postdoctoral researcher at NC State. The post is an entry in an ongoing series that we hope will highlight the diversity of researchers in science, technology, engineering and mathematics. The series is inspired by the This Is What A Scientist Looks Like site.

My name is De Anna Beasley. I’m a postdoctoral research scholar with Rob Dunn in the Biological Sciences Department at NC State. As an insect ecologist, I am broadly interested in studying the effects of environmental stress on insect development and function.

My research has ranged from studying the impacts of radiation on wing asymmetry in grasshoppers (as part of the Chernobyl Research Initiative at the University of South Carolina) to habitat degradation on cicada egg-laying site selection.

De Anna Beasley, doing research in the field. (Photo credit: Lauren Nichols.)

De Anna Beasley, doing research in the field. (Photo credit: Lauren Nichols.)

My current focus at NC State is on understanding how immunity and host-microbial interactions in social populations, such as ants, respond to diet and temperature changes. This new direction has led me into exciting research and collaborations related to microbial ecology, social insects, nutritional ecology and urban ecology!

I never thought I would be a researcher, though I always enjoyed science and asking questions.

Growing up, my plans were to go to medical school and become an OB/GYN. However, I was pretty burned out with the pre-med track by my senior year of college. I took ecology and toxicology courses and really enjoyed them both! I liked the idea of exploring how organisms might respond to changing conditions and how the environment shaped populations.

I didn’t get into insects until after I started graduate school. Even then, appreciation developed slowly. I worked with cockroaches, grasshoppers and cicadas, asking questions related to how well they developed wings or how mounting an immune response impacted other physiological processes such as reproduction. My current project involves working with ants and I think they are pretty impressive and fun to study!

I’m truly excited to be working with the Dunn lab group because it gives me an opportunity to not only work with some amazing researchers and ask cool questions but also participate in public outreach events. I think it’s important for researchers to share their knowledge and enthusiasm for scientific research with the general public with the hope of encouraging young people to ask and pursue science questions on their own.

When I’m not in the lab or field, I enjoy Tai Chi, hang gliding and spending quality time with friends and family. These activities help balance and provide meaning to my life.

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