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Posted on Sep 16, 2014

NC State Receives Grant to Improve African Sweet Potatoes

North Carolina State University will receive $12.4 million over the next four years from the Bill & Melinda Gates Foundation to improve a crop that is an important food staple in sub-Saharan Africa – the sweet potato.

The grant will fund work to develop modern genomic, genetic and bioinformatics tools to improve the crop’s ability to resist diseases and insects and tolerate drought and heat. Sweet potatoes are an important food security and cash crop with potential to alleviate hunger, vitamin A deficiency and poverty in sub-Saharan Africa. More than 13.5 million metric tons are produced in sub-Saharan Africa annually; they are predominantly grown in small plot holdings by poor women farmers.

A priority crop for the Gates Foundation’s Agricultural Development Program, the sweet potato has a complex genetic blueprint. Lack of knowledge about the crop’s complex genome and lack of modern breeding tools for the crop currently hamper efforts to expand production.

Dr. Craig Yencho, an NC State professor of horticultural science who heads the university’s sweet potato breeding program in the College of Agriculture and Life Sciences, is the project director. He says that sweet potatoes have a number of valuable characteristics that make them an attractive African crop.

“Sweet potato is a hardy crop that can be planted in drought-prone and low-fertility soils,” Yencho said. “Orange-fleshed sweet potatoes, which are an excellent source of vitamin A, rank first in nutritional quality among root and tuber crops grown in sub-Saharan Africa, providing vitamins for millions of people.”

He adds that – besides the crop improvement work – it’s important to build a network of young scientists who can use the new breeding tools and techniques built in this golden era of genomics.

“NC State has a long history of commitment to developing Africa’s sweet potato breeding programs,” Yencho said. “We will work very closely with the sweet potato breeding community to identify young breeders for advanced training to build long-term capacity in use of genomic breeding. During the project term, we will make efforts in training to ensure that new researchers and partners are fully capable of employing newly developed tools.”

Chancellor Randy Woodson praised Yencho’s work on sweet potatoes in Africa and in North Carolina, which leads the United States in sweet potato production.

“Dr. Yencho’s work on this important crop has led to a number of new varieties and improvements in sweet potatoes grown across the world, and is an excellent example of NC State’s think-and-do mentality,” Woodson said. “The international collaboration he’ll head will use interdisciplinary teams to gain critical knowledge – and share that knowledge – to help feed a continent.”

Woodson added that the $12.4 million grant is the latest example of continually increasing private support for NC State as the university prepares to launch the most ambitious fundraising campaign in its history. “This type of generous support enables NC State to extend the impact of our life-changing work across the nation and throughout the world,” he said.

NC State co-primary investigators include Dr. Fred Wright, professor of statistics and director of the Bioinformatics Research Center; Dr. Dr. Zhao-Bang Zeng, William Neal Reynolds Professor of Statistics and Biological Sciences; Dr. Dahlia Nielsen, associate professor of biological sciences; Dr. Jennifer Schaff, director of NC State’s Genomics Research Laboratory; and Dr. Lina Quesada-Ocampo, assistant professor and extension specialist in plant pathology.

Partners on the grant include the International Potato Center; Michigan State University; the Boyce Thompson Institute at Cornell University; the University of Queensland; the National Crops Resources Research Institute in Uganda; and the Council for Scientific and Industrial Research in Ghana.

- kulikowski -

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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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