By Ernestine Bousquet
Zhenhai Xia is working to perfect synthetic dry adhesives based on the Spiderman-like prowess of geckos. Jaehyung Ju has helped to reinvent the tire by taking out the air and is now studying ways to make airless tires safer, more fuel efficient and even greener.
Stevens Brumbley is engineering plants -- specifically sugarcane -- to produce a range of bioplastics, which will provide alternatives to petroleum-based plastics. Ruthanne Thompson is showing schools how using wind and solar power technology can save money. And while she's at it, she's analyzing what makes the best urban-scale wind and solar power system to help power neighborhoods.
Researchers at the University of North Texas are working to develop technologies and products designed by nature or designed with nature in mind. They work in many disciplines -- from engineering and plant science to environmental science and philosophy -- and together are distinguishing UNT as a premier place for green research.
The university's strong environmental legacy began in the 1930s with water research. Now, with solutions-based research clusters and innovative degree programs in areas such as mechanical and energy engineering, UNT is standing out in new ways.
If Spiderman were real, his hands and feet would work like gecko feet, says Xia, a member of the Materials Modeling research cluster and the Center for Advanced Scientific Computing and Modeling at UNT. Geckos can climb any vertical or horizontal surface, sticking to it and detaching easily while their feet stay clean.
The quick-release adhesion is attributed to the unique structure of the millions of microscopic hairs on their feet and van der Waals force, which allows them to generate a strong adhesion force to defy gravity but easily detach from a surface by peeling their feet away.
Xia was part of a team of researchers, led by Liming Dai of Case Western Reserve University, who made gecko-inspired dry adhesive that was 10 times stronger than gecko feet by mimicking gecko footpads using carbon nanotubes. The palm-sized adhesive was estimated to be strong enough to support a 200-pound man climbing a wall, but easy to remove and re-adhere upon many reapplications. Their research was published in Science magazine. Because of the tubes' strength and flexibility, they also could be used as structural material in such things as car parts and baseball bats.
Now, Xia, associate professor of materials science and engineering, is further exploring the hair of gecko feet. His team has discovered a self-cleaning mechanism in the feet and, based on the finding, will create artificial gecko feet for testing.
The research could be used to help create dry synthetic adhesives that would be strong and reusable, remaining sticky and clean after each application. The advanced adhesion technology could be used for applications such as bonding material in the biomedical field or electrical components. He is hoping the research also could lead to cheaper ways to fabricate the adhesive.
Xia focuses on biomimetic research, which looks to nature to design materials and devices. Nature has had millions of years to perfect the design of animals and plants, he says, and from it we can learn to create new, better and greener materials.
"As scientists, we need to solve big problems," Xia says. "If we solve big problems, we make life easier and help protect the environment."
Xia also has been researching how to improve clean-energy technology for cars and power plants. He was part of a team that had a breakthrough in fuel cell technology, discovering that nitrogen-doped carbon nanotubes are nearly four times better than platinum as a catalyst and could eventually replace it in fuel cells. These findings also were published in Science.
Xia says the high cost of platinum is one of the major barriers for fuel cell commercialization. Carbon is easy to find and cheap to mass produce, so it is a more renewable resource than platinum. Carbon nanomaterial also is a better catalyst for oxygen reduction -- a key chemical reaction that generates electricity in fuel cells -- so it can make a clean technology better and cheaper. Xia is now working to better understand the catalytic mechanisms in fuel cells.
In the mechanical and energy engineering department, tires are getting an overhaul too. Ju, an assistant professor and researcher in UNT's PACCAR Technology Institute, contributed to the development of the airless or non-pneumatic tire. On the market within perhaps a decade, the tires are made of polyurethane and rely on a structure of flexible spokes for stiffness instead of air. Because the tires won't go flat, they have a longer shelf life, meaning fewer would end up in the landfill compared to conventional rubber tires.
Ju has analyzed the airless tire's rolling resistance to see how it handles energy loss. He has found that airless tires have a 10 percent lower rolling resistance than traditional tires, which translates into better fuel efficiency and a safer road experience.
Now Ju is working to improve the design and safety of the airless tire. He is developing porous polyurethane composites that could lead to a 20 percent lower rolling resistance. He also is applying his research in cellular topology, the lattice geometries that control the stiffness and strength of cellular materials, to improve the design.
His research team members are using a multiscale modeling and design technique that covers the materials design and structural performance of a real tire model. He says they are close to matching the safety of the conventional tire.
Motivated by collaborations with faculty in UNT's Renewable Bioproducts research cluster -- including Nandika D'Souza, professor of mechanical and energy engineering and materials science, and Sheldon Shi, associate professor of mechanical and energy engineering -- Ju envisions creating an airless tire made of eco-friendly material such as nanowhisker-reinforced natural rubber. He also is looking at ways to use recycled rubber tires for creating other products such as building materials.
"UNT is focused on sustainable technology," Ju says. "It's great to collaborate with other researchers who have expertise in this area."
Brumbley, associate professor of biological sciences in the Renewable Bioproducts cluster, is working at the new Research Greenhouse Complex at Discovery Park, UNT's 300-acre research park. He is engineering C4 grasses such as sugarcane to create more environmentally friendly plastic.
Most of the plastic in our lives is made from petroleum-based resources, but that is starting to change as major manufacturers are driving demand for green plastics, Brumbley says. Bioplastics are made from renewable resources, have a lower carbon footprint and are, in some cases, biodegradable.
The C4 grasses are ideal crops for bioplastics because they efficiently use sunshine and carbon dioxide to produce biomass, are abundant and can easily be re-engineered, Brumbley says. Certain kinds of grasses also are drought tolerant and will grow on lands not suited for food crops.
Sugarcane is one of the more advantageous C4 grasses for bioplastics because it is already grown and produced for sucrose. Where there is sugarcane production, there is infrastructure to grow the cane, harvest the biomass, transport it to a central processing plant and crush it. Waste from the production helps provide the energy to run the mill.
To engineer the sugarcane, Brumbley isolates genes from various bacterial species that make the necessary chemicals and transforms the sugarcane so these genes become part of its genome. Bioplastics or precursors are then made in the cells of the sugarcane plants and accumulate there until harvested.
He says the field is in its infancy but growing rapidly, and bioplastics have huge potential for use in everything from packaging to electronics, automobiles and airplanes.
"In addition to reducing petroleum use, bioplastics could displace a large amount of plastic that is either going into landfills or showing up as part of an ongoing pollution problem," he says. "They also can be a key solution for corporations dealing with legislation on products that don't biodegrade and aren't being recycled."
As the demand for smaller, more energy-efficient electrical devices grows, electrical engineers must determine how to best fit all the electrical components into the devices. Gayatri Mehta, assistant professor of electrical engineering, and student researchers have turned the problem of efficiently mapping electrical components into a web-based computer game, Untangled, which could lead to new algorithms.
The game unlocks the secrets of human intuition by requiring players to arrange various series of blocks on a graph. By mathematically analyzing the graphs of the top-scoring players, the team hopes to develop new algorithms to help engineers develop the next generation of cell phones, medical devices and other electronics. Mehta's National Science Foundation-funded research could lead to smaller, more energy-efficient devices. The game has been named a finalist in the NSF-sponsored International Science and Engineering Visualization Challenge, one of the top 10 in the Games and Apps category.
Peter Collins, assistant professor of materials science and engineering, is focused on developing high-strength, lightweight alloys that might be used to create lighter vehicles that are more fuel efficient while still retaining their design strength levels. As director of the UNT site of the Center for Advanced Non-ferrous Structural Alloys -- an NSF-sponsored Industry/University Cooperative Research Center -- Collins is part of a team working to develop lightweight alloys used in airplanes and cars.
The work of Mehta and Collins could play an essential role in improving the efficiency and performance of everyday technology, leading to positive impacts on the environment.
At UNT's Environmental Education, Science and Technology Building, Thompson, an environmental scientist, can tell at any given moment how much energy the 3.5 kwh wind turbine and four-panel solar array are producing to help power the greenhouse there.
Both a practical energy source and a demonstration project, the system is Thompson's brainchild, part of her SMART Schools initiative funded by a grant from the State Energy Conservation Office. Through the initiative, Thompson, associate professor of biological sciences, used research and modeling to help eight Texas schools or school districts implement technologies to save energy and educate students about energy conservation. The grant also helped fund a wind and solar system at UNT's Zero Energy Laboratory, a unique facility to research renewable energy technologies.
Thompson's applied science is equal parts research and education. She creates math and science lessons based on the data from the two systems. And she is analyzing which system is better at producing energy and offsetting energy costs so that she has strong research to encourage the use of urban-scale systems. She also goes to local schools to teach students how to reduce water consumption. She's found they are taking the lessons to heart and back to their families.
"I try to make connections through real-world applications," Thompson says. "This not only helps students see the effects of their actions, it can help make future scientists."
As an environmental anthropologist, James Veteto, assistant professor of anthropology, also does outreach-based green research. He directs the Southern Seed Legacy program, working to collect and conserve Southern heirloom seeds and their histories with a particular focus on seeds threatened by genetic erosion or extinction. The program serves as a seed reserve for plant varieties in danger of becoming extinct and as a memory bank documenting the cultural history of Southern heirloom plants.
Veteto and other researchers help to identify at-risk crops important to regional biodiversity and sustainable agriculture, then work with farmers to preserve them and to promote local seed exchanges. They want to reverse further loss in the diversity of crops in the American South.
UNT's reach extends around the world. Through the Sub-Antarctic Ecosystems and Biocultural Conservation research cluster, UNT researchers are partnering with researchers in Chile to protect and support the ecologically fragile Cape Horn reserve -- one of the world's last remaining pristine wilderness areas.
The cluster includes researchers from UNT's nationally recognized programs in environmental philosophy, biological sciences and ecological sciences.
Co-directed by faculty members Ricardo Rozzi and Eugene Hargrove in philosophy and James Kennedy and Jaime Jiménez in biological sciences, the program combines cultural and philosophical perspectives with empirical scientific research. Through the UNT-Chile Field Research Station, students and faculty conduct hands-on research on climate change, habitat conservation and language loss.
These initiatives are helping UNT become known as a hub for green research in everything from renewable energy technologies to bioproducts and conservation, says Geoff Gamble, vice president for research and economic development.
"Many of the challenges of the 21st century have to do with minimizing human impacts on the environment, and UNT researchers are tackling these challenges through innovative, collaborative research and outreach," Gamble says.
"We are attracting researchers who are leading the way in these fields and students who want to learn from these innovators."
The university officially unveiled the UNT Zero Energy Laboratory at Discovery Park, its 300-acre research park, in 2012. The new state-of-the-art laboratory -- the only one of its kind at a U.S. academic institution -- will advance UNT's research capabilities, solidifying the university as a leader in zero-energy research and instruction.
"There are very few other places for students to get hands-on experience working with the green technologies that will power our future," says Yong Tao, chair of the Department of Mechanical and Energy Engineering and PACCAR Professor of Engineering, who spearheaded the design and creation of the lab. "This facility is a great resource for our students, researchers and industry partners."
The 1,200-square-foot space was designed, with input from industrial partners, to test energy technologies such as solar, geothermal and wind systems that produce enough energy to power a building, helping it achieve a net-zero consumption of energy. In many cases, the technologies even create excess energy to return to the power grid.
The lab includes solar panels, a building energy monitoring and control system and a rainwater collection system. Outside, the facility has a residential-scale wind turbine.
Tao oversaw a similar project at Florida International University, where he was associate dean of the College of Engineering and Computing. He also initiated and served as the director of the Future House USA project, an initiative that brought together academics, builders, industry sponsors and lobbyists to create a 3,200-square-foot net-zero energy house.
The American House was built in Beijing and displayed during the 2008 Olympic Games. UNT furthered its relationship with Chinese researchers by signing a memorandum of understanding with Future House Real Estate Co. Ltd., a research institution in Beijing, in 2011.
Last summer, Tao took a group of students to Beijing and Shanghai to study alternative energy. They studied renewable, solar, wind, geothermal, biomass and zero-energy buildings. They also visited the world's leading manufacturer of solar panels and lived in the Beijing American House for a week.
Rambod Rayegan, a visiting assistant professor in the Department of Mechanical and Energy Engineering, is overseeing the research in the Zero Energy Laboratory. Postdoctoral researchers and graduate students are studying areas such as whole-building energy performance model validation, the long-term impact of the interaction of soil and ground source heat exchangers, alternative HVAC systems for zero-energy buildings, innovative thermal storage for solar energy and the role of human behavior in energy usage.
The lab was designed so that structures such as doors, windows and supporting energy-efficient equipment can be expanded and exchanged to facilitate research. Nandika D'Souza, who has a joint appointment in the Department of Mechanical and Energy Engineering and the Department of Materials Science and Engineering, hopes to use the facility to test materials made out of the fibers of the kenaf plant in Texas and others from Qatar and Brazil.
The bio-based construction materials would be more environmentally friendly than traditional building materials and could reduce energy usage. D'Souza is working with Tao and other faculty on the project with a National Science Foundation Partnership for Innovation Grant. She and Tao are members of the Renewable Energy and Conservation research cluster, and she oversees the Renewable Bioproducts research cluster.
Both groups will take advantage of this unique facility to conduct cutting-edge sustainability and energy research.
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