RESEARCH
RESEARCH
Chemist discovers new molecular structure
When Virginia Tech chemistry Professor Harry Gibson came up with the idea of threading cyclic--also known as ring or closed-chain--molecules onto linear polymers, materials made up of two more smaller molecules, he created a new molecular structure called polyrotaxanes. Gibson and fellow researchers already have developed a water-soluble polyurethane as a result, and the discovery possibly could lead to work in molecular-level electronic devices.
According to Gibson, who is a researcher in the National Science Foundation and at Virginia Tech's Technology Center for High Performance Polymeric Adhesives and Composites, the cyclic molecules and linear polymers in polyrotaxanes are physically linked instead of chemically bonded, which allows the cyclic molecules to move along the linear ones. That mobility is not possible in chemical bonding, which drastically alters the solution, thermal, and mechanical properties of the polymers, Gibson says.
One of the main advantages of linking the cyclic material with the linear molecules is an increased solubility. The new water-soluble polyurethane already developed might be used to create a product that allows manufacturers to avoid the use of toxic or flammable organic solvents. For example, Kevlar, used to make bullet-proof vests and tire cord, can be processed only by using concentrated sulfuric acid, causing a problem with waste disposal. Polyrotaxanes might eliminate that processing problem, Gibson said.
Another more speculative use of the discovery is in making conducting or photo-conducting polymers. "If we had a situation in which we have an interaction between the rings that allowed them to transmit electrons from one to another, then we could begin to think about making conducting molecular devices--molecular diodes," Gibson says.
It also would allow for the development of molecular-level electronic devices, which exist only on the macroscopic scale now. "If we could get it on the molecular scale, we could operate on a 10,000-times-smaller scale," Gibson says. The problem then would become how to program a molecular-sized computer, he adds.
The National Science Foundation has funded Gibson's basic work and the Technology Center has given support.
Pharmaceuticals from toxic wastes?
Virginia Tech chemistry professor Tomas Hudlicky has developed the first step in a process that could help eliminate the need for additional toxic waste dumps, allow for more economically produced pharmaceuticals, and possibly could play a role in research on the virus that causes AIDS.
Hudlicky already has made more economical pharmaceuticals in his lab utilizing previously developed methods for using genetically altered bacteria to oxidize toxic materials. He now believes the process could be developed to alter chemicals that currently have to be stored in toxic dumps. He also found the method leads to good synthesis of nitrogen-contained sugars, which are seen as potentially important in studies of HIV.
Hudlicky first used the process in 1988 when he made a class of hormones from toluene, an aromatic solvent. "We made a drug that costs $130,000-$140,000 per gram in pharmaceutical markets by using microbiology and synthetic chemistry in tandem," Hudlicky said. "Our cost is about $200 per gram." He has since made simple sugars and artificial sweeteners, gotten two major pharmaceutical companies interested in his work, and made known drugs by using bacterial degradation.
Hudlicky now believes the process he developed could eliminate the need for dumps for toxic chemicals such as chlorinated aromatics, including PCBs, by turning those substances into sugar and other useful compounds. Chlorinated aromatics eventually could be turned into pure table sugar indistinguishable from sugar obtained from cane.
A major part of the process being used at Virginia Tech was developed by David Gibson of the University of Iowa, but Hudlicky's group was the first to realize the potential for turning toxic substances into useful ones. In the lab, Hudlicky exposes an aromatic compound to mutant bacteria, which oxidizes the compound into something normal bacteria would use as a source of energy. He then provides the mutant with an alternate energy source, and allows the resulting chemicals to accumulate. After he isolates and removes the oxidizing substance from the culture, a few short steps chemically modifies it into a sugar.
Hudlicky had once hoped the process could be used directly on existing toxic dumps, but he now says compounds will more likely be treated before they are dumped. Although much of the necessary technology still must be developed, "it should be cheaper than dealing with it as waste," he says.
Ancient plants tell story
A Virginia Tech scientist who helped uncover an unexpected diversity of ancient plants on an arctic tundra says the discovery could help answer some complex questions about one of the most critical periods in the evolution of life.
Stephen Scheckler, a specialist in the reconstruction of prehistoric plants, found the plant fossils on Ellesmere Island, the largest and most northerly island in the Canadian arctic, while working with James Basinger, a professor of geology and biology at the University of Saskatchewan. The two have discovered at least seven new plants dating from the Devonian period--345 million to 360 million years ago.
The discovery is potentially important because the scientists are examining the period when the earth's surface was starting to change from purely shrubby vegetation to forests, a time during which experts believe animals first started moving onto land. The fossil forests and shrub thickets Scheckler and Basinger discovered would seem to indicate Devonian plants grew in areas with more pronounced wet and dry seasons than previously thought. It also could challenge the theory that the late Devonian had uniform plant communities worldwide.
Scheckler says the discovery also might disprove the theory that a uniform mass extinction caused by an asteroid or something similar wiped out virtually all marine and plant life late in the Devonian. Scheckler says understanding how plants and animals adapt to major extinctions is important because ecosystems are bound to collapse occasionally during the life of the Earth. Scheckler believes deforestation and the possibility of global warming could be setting up conditions for the next mass extinction.
Ventilation system could provide breath of fresh air
Virginia Tech experts are testing whether a ventilation system that moves air through a perforated floor and then vents it through the ceiling could be a commercially sound method for improving indoor air quality.
The upflow displacement ventilation project, which is being funded by a $1.2-million grant from Philip Morris U.S.A., is being directed by James E. Woods, the William E. Jamerson Professor of Building Construction in the College of Architecture and Urban Studies. The system was developed by a team of Philip Morris engineers.
"There are two basic methods of controlling indoor air quality," Woods says. "One is to remove the source and one is to minimize exposure to contaminants caused by the source. This research...focuses on exposure-control technologies that augment source control as a means of removing contaminants from occupied spaces."
The system, known as Filtered Air Control Technology, takes clean air from a sub-floor space and pushes it through floor perforations below a modified commercial grade carpet, tile, or other material. The room air, which is exhausted through ceiling vents, filtered, and then returned, is replaced every two minutes. One potential benefit is that the air flow would keep contaminants--such as tobacco smoke--from reaching other people in a room. "The objective of the project is to determine if displacement ventilation is an economical and technically sound means of improving indoor air quality," Woods says.
The test will be conducted in two equal-sized office areas constructed at the college's Research and Demonstration Facility using volunteer office workers now employed by Virginia Tech. The project also will be reviewed by an outside advisory committee. Woods, who has testified before congressional committees about indoor air quality issues, is a technical advisor to the American Lung Association, and is a member of the Building Research Board of the National Research Council, the Science Advisory Board of the Environmental Protection Agency, and the American Society of Heating, Refrigerating, and Air Conditioning Engineers.
Praise pushes girls' success
Parental support and expectations--as well as a strife-free environment while growing up--have more to do with women's success in life than does socio-economic status, according to a study by Sigrid Gustafson, assistant professor of psychology and senior author of the book Female Life Careers: A Pattern Approach.
Status, concluded Gustafson and colleague David Magnusson of the University of Stockholm, really did not mean much as long as a girl's parents believed in and expected her success. "We found patterns where parents were very low in socio-economic status--in income and education--but were upwardly mobile in their expectations for their children. They wanted their children to go on and believed they could," Gustafson says. "The patterns set up early in a child's life cause them to have different life courses."
Gustafson and her colleagues looked at a large sample of Swedish families at all rungs of the socio-economic scale over 30 years. Gustafson paid particularly close attention to the parents' expectations about their daughter's continuing education and success, as well as their belief in her capability for continuing her education. They looked at the girls at ages 13, 16, and 26.
The highest achievers in all groups came from households where the parents believed the daughter would succeed. One group of 13-year-olds actually had higher abilities and achievements than the average at that age, but their perception of their ability and their family's encouragement was low. By age 16, they were underachieving significantly. By age 19, the same group had had more abortions than their counterparts. By age 26, they held only part-time jobs, had more children, reported fewer personal friends, and expressed less satisfaction with their use of leisure time. The same group of girls also had some strife in their families.
On the other hand, the 13-year-olds with high perceptions of their abilities and high adaptations to school came from families who "thought they were hot stuff." They went to college, established careers, married later, and had fewer children. "The whole environment--schools and families--rewarded their staying in that pattern," Gustafson says.
Gustafson says the study simply points out things parents can do to increase children's chances of success. "Parents can reinforce their childrens' abilities," Gustafson says. "The underachievers were not dumb. They were normal at 13. But by 16 they were lower. The overachievers had lower IQs, but their high achievement came from families going 'rah, rah, rah.'"
Virginia Tech Magazine Volume 14, Number 3 Spring 1992