UC Davis researchers made a surprising discovery while exploring the unusual electronic properties of a multi-layered nanoscopic structure. Depending on which way its electrons move, the material either behaves like a typical semiconductor or exhibits peculiar features unique to a single-layer carbon material that is now touted for its promising potential in electronic applications.

At a subatomic level, the researchers found that electrons in a vanadium dioxide network act like particles with mass while traveling in one direction, and particles without mass while moving in the perpendicular direction. The vanadium is layered between insulating sheets of titanium dioxide so that movement of its electrons is restricted to two dimensions.

“It’s almost as if the laws of physics governing their dynamics are different along the forward direction and the sideways direction,” said Warren Pickett, professor and chair of the physics department at UC Davis.

Researchers once thought that mass-less particle behavior was limited to situations where particles travel near the speed of light such as in accelerators and outer space. This view changed five years ago when physicists at the University of Manchester isolated graphene, a one-atom-thick sheet of carbon arrayed in a honeycomb shaped lattice. The equivalent behavior of electrons in graphene was dubbed “Dirac-like” in honor of the physicist who coined an equation for mass-less particle behavior.

Unlike graphene, the three-tiered vanadium oxide lattice does not purely exhibit Dirac-like properties, so Pickett and his colleagues termed the phrase “semi-Dirac” to describe the distinctive dual behavior of its electrons moving in two dimensions.

The new nanostructure currently exists as a computational model, but Pickett is certain that its electrical transport properties – particularly conduction in a magnetic field – will be unlike anything seen before in real world materials.

In the past few years, researchers have discovered interesting yet poorly understood “conducting interfaces” located between the two insulating materials in similar oxide nanostructures, Pickett said.

“We think semi-Dirac and Dirac behavior may be much more widespread than initially thought, especially in nanoscale layered materials, in which case it should find its way into applications in electronic devices,” said Rajiv Singh, UC Davis physics professor, who was not involved in the study. “But we do not know yet how or where exactly it will happen.“

According to Pickett, new methods that harness the tiny scale and unusual properties of such materials have been proposed to surmount physical limitations in the development of smaller, more complex microchips.

Instead of growing nanostructures into active devices such as transistors in a computer chip, the nanomaterial itself could serve as the base on which circuits are designed and etched into using a very fine tip to “provide conducting strips in an otherwise insulating material,” Pickett said.

The multi-layer vanadium oxide lattice is more rigid than one-layer graphene, which makes it particularly well-suited for this purpose, he added.

Pickett and Rajiv recently devised a mathematical model to further examine and describe the material’s macroscopic properties such as how temperature and magnetic fields affect its ability to conduct an electric current.

Pablo Jarillo-Herrero, a physics professor at Massachusetts Institute of Technology, said he agrees that more theoretical and experimental work is needed to determine the material’s basic characteristics and to test predictions about electron dynamics before proposing real world applications.

“The theoretical results seem quite interesting … but the implications for electronic devices are not clear since transport in these systems occur often in a diffusive manner,” said Jarillo-Herrero, who was not involved in the study.

Details about the material and its properties were published in the Apr. 22 issue of Physical Review Letters.

ELAINE HSIA can be reached at features@theaggie.org.

Students might have more of an incentive to lower their carbon footprint if they were given cash prizes of $10,000. America’s Greenest Campus competition is doing just that.

America’s Greenest Campus is a nationwide competition sponsored by the organization Climate Change to get students, faculty and staff from universities across the U.S. to become more aware of their impact on the environment.

Total prize money will near $20,000. The first tier of the competition will end Friday online at americasgreenestcampus.com to see which university can get the most people to sign up throughout the week. The prize will be $500 to be used toward a party or festival to celebrate sustainability. ASUCD’s Campus Center for the Environment (CCE) is leading the competition for UC Davis.

“I’d like to think that UC Davis is a leader in environmental sustainability practices and awareness,” said Will Klein, current co-director for the CCE. “This is a good way to get our name out there and show that we are still leading the way.”

If students sign up between now and Friday, the process only taking roughly five minutes, they will also be entered into a random drawing for a cash prize, Klein said.

Other components of the competition include a $5,000 prize with the school that has the most people to sign up by Oct. 5. Another $5,000 prize will be awarded to the university with the most carbon reduction by Oct. 5. The third tier includes a video competition, with the reward totaling of $10,000.

“The idea [of the competition] is that if you see that your actions have an affect on the overall carbon level, you can then change that by changing your individual behavior,” said Klein, also next year’s unit director for CCE. “If you can see that other people are doing this with you, you can feel much more powered knowing that you’re not in it by yourself.”

This money could aid UCD’s environmental projects and bring awareness to the importance of maintaining a low carbon footprint.

“There are a lot of students that have a lot of great ideas, but not enough funding,” Klein said. “We would give [the prize money] all back to students who can implement these sustainable practices.”

Lauren Jabusch, a co-director for CCE, emphasized changing the little things for an overall larger impact.

“It’s good to know what everyone’s impact is and use that as a benchmark. Just look for little ways that you can cut back, not exactly big changes or steps – look to make conscious decisions instead of unconscious about the environment,” Jabusch said.

The website asks the participant questions regarding current factors that may contribute to your carbon footprint such as the size of one’s home, modes of transportation or computer usage. After signing up, participants can browse the site for other ways to reduce their carbon footprint.

“Carbon isn’t really a top factor in our daily decision making. We don’t think about the impact of emissions, or if we buy something it doesn’t directly need carbon, but the process to make it does,” Klein said.

Jessica Bray of CCE reduces her footprint by maintaining a vegetarian diet, shopping at local places with local produce, such as the Davis Food Co-op or Davis Farmers Market, and primarily using her bike or public transit.

“UC Davis can learn new practices to adopt to lower our carbon footprint. As learners of the world the competition should make students, faculty and staff more aware of sustainability on American college campuses,” Bray said in an e-mail.

CCE will be tabling on the Quad throughout this week till Friday, the end of the $500 prize portion of the competition. To sign up, visit for americasgreenestcampus.com.

ANGELA RUGGIERO can be reached at science@theaggie.org.

When Dr. Koen Van Rompay is not researching drugs for HIV and AIDS, he is actively participating in educating people in developing countries on HIV preventative measures.

What is your occupation?

I’m basically a scientist. My official title is associate researcher, but I’m being promoted to full-researcher in July.

What are you currently researching?

I do HIV and AIDS research on primate models. We are trying to get a better understanding on how HIV causes disease, and we are working on cure strategies for both prevention [of HIV] and to treat people who may already be HIV infected.

What projects are you currently working on?

We are drug testing; there are many drugs on the market that treat HIV, but we are trying to find out if it is possible to cure the infection. We are trying to eliminate the virus so that people can stop taking medication [for HIV]. We’re testing [the drugs] on monkeys, and we hope to develop them enough to begin human clinical trials.

Do you work with HIV infected people?

[At UCD] I only work at the primate center, but I also do nonprofit work that is separate from my work at the university. I work with HIV infected children and adults in developing countries, some of which is funded by the Elton John Foundation.

How is working with children infected with HIV different than working with HIV infected adults?

Many children who are HIV infected develop the disease faster. It’s more important for children to get an early diagnosis so that they can start HIV therapy sooner. The formula for medication for children is more difficult, for example, for HIV infected babies you have to be able to give them the medication in liquid form since they can’t swallow a pill. It’s difficult for many adults to get [HIV] drugs, but it’s even more difficult for children to get drugs.

How does HIV affect children differently than it does adults?

When adults get infected with HIV, their immune system can control the virus for many years before it becomes a full-blown disease. Whereas [with] children, their immune system isn’t as strong so the virus attacks their immune system. Especially with babies. One-third of babies who get HIV will develop AIDS within a year.

If a vaccination is produced for HIV infected children, would it help adults?

That’s possible, we are testing vaccines that would hopefully protect babies from getting infected. There are medications available in developing countries which, if you give them to the [HIV infected] pregnant mother, it can help the baby. Breast milk is the best solution. We’ve been testing some drugs on monkeys that are very promising. Babies would be vaccinated through the breast milk by a drug that the mother was taking. The monkey studies suggest that a child vaccination would work for adults, but we have to wait for human trials.

You founded the nonprofit organization Sahaya International. What does your organization do?

We have many different programs. We work with the student club on campus called Sahaya International [and have] programs in Kenya and in India. We build schools in small villages that don’t have schools.

We work with an orphanage in India; [the orphans] are typically children who are living with an uncle or aunt or grandparents. We help that family by providing one dollar per day. The people who sponsor the children get a few letters from the child every year and a photograph. Many sponsors have gone from Davis to India to meet their sponsor-child in person. We are sponsoring 152 children.

We also work with deaf/mutes to teach them about AIDS in India, [and with] self-help groups or women. We give them micro-loans to start businesses. We work on many different things and many different issues. AIDS isn’t just a medical issue, it’s a social and economic issue.

What inspired you to start Sahaya International?

I got invited to a conference in 1997 that was being held in India. I went there as a scientist, but before the conference I had two days to do some sight seeing. I got to see some temples, which was amazing, but I also saw the poverty. Seeing the children begging for food was very hard and I felt like I had to do something. You could give a child money for food but that only helps for so long.

At the AIDS conference, I met a social worker who was working at a small village helping the women. I offered to help with the cost of providing women with sewing materials. That’s how it got started and it’s just been building up for over the last 10 years. Through our network of friends, we have been able to accomplish a lot. For me, my goal is to combine both my research and Sahaya International.

Do you think that we will ever find a cure?

Do I hope so? Absolutely. If each of us makes the right decision at the right time, we are dependent on our scientists and the government to help us, but it’s down to us. We have to respect each other and take responsibility for our own actions. Even just talking to our friends about HIV and AIDS, that can make a difference. It’s dangerous to not be hearing about AIDS, children who are becoming sexually active must be aware of HIV and AIDS. We have to keep awareness high.

MEGAN ELLIS can be reached at features@theaggie.org.