MICROSCOPES
Geologists learning uranium containment from Nature
Three
decades ago, possibly one of the richest uranium deposits in the United
States was discovered at Coles Hill in rural south-central Virginia. Although
the deposit was considered for mining, it was never developed. Now, this
site may yield knowledge of great value as a natural laboratory or radioactive
waste containment.
“The
uranium has just been sitting there for hundreds of thousands of years,“ says A.K. Sinha, professor of geological sciences
at Virginia Tech. “Sitting there” are the operative words.
“There is a water table about 11 meters (36 feet) down, and the uranium-rich
bedrock about 20 meters (66 feet) down. The uranium should have migrated
to the next county, but it hasn’t.”
“You
would expect groundwater in this type of natural system to have carried
the uranium away from the site into the surrounding environment, but we
don’t see that,” says Virginia Tech Ph.D. student Jim Jerden
of Atlanta, Ga. “We think we can learn something from this site that
can be applied to existing contaminated sites and nuclear waste repositories.”
Sinha explains, “Uranium is toxic, particularly when it is concentrated, such as
in nuclear fuel, weapons, and radioactive wastes. In nature, there are
deposits that are extremely concentrated and they should be of great concern,
as uranium may be transported in solution through groundwater activity.
But, in nature, things have a way of reaching a ‘steady state’.
The Coles Hill deposit, for instance, shows no measurable evidence of
leakage into the surrounding soils and rocks. This ‘natural analog’
provides a scientific window where we can study what prevents uranium
from contaminating its surroundings.”
As geologists,
Sinha and Jerden are looking at the natural system that contains the Coles
Hill uranium deposit as a unique geologic analog for uranium-contaminated
sites and nuclear waste repositories. “Nature may present a model
for the scientifically sound management of nuclear wastes and contaminated
sites,” says Jerden.
Research funded to create stronger fuel cell materials
Chemistry professor James McGrath’s success in strengthening polymer materials for
use in fuel cells has garnered a lot of support.
McGrath’s team, which includes researchers at Los Alamos National Lab and Virginia Commonwealth University, as well as from chemical and materials engineering at Virginia Tech, received a $600,000 grant from the National Science Foundation, $2 million from the Department of Energy, and $500,000 from just one industry partnership alone — in addition to support for specific projects from such agencies as the Office of Naval Research and NASA.
McGrath and colleagues report promising advances in the the effort to make fuel cells affordable — using inexpensive polymers instead of the rare materials NASA has used. The group is doing research on the polymer electrolyte membranes (PEMs) within fuel cells, which filter hydrogen protons out of the fuel and pass the protons into the chamber where they merge with oxygen to produce energy. The researchers are developing polymers that can operate at higher temperatures than present day PEMs, and are more conductive. They reported several successful strategies for creating better PEM materials at the American Chemical Society (ACS) meeting in late August, 2001.
Find ACS news releases about McGrath's work at EurekAlert.org, for example:
Researchers
improve thermal stability of fuel cell materials
Chemists
increase conductivity of fuel cell materials
Evidence found of recognition between animate and inanimate objects
For decades,
people have been interested in how microbes attach and release from mineral
surfaces. The interaction is fundamental to the way microorganisms are
transported through water treatment facilities, the effective use of agrochemicals,
or the movement of toxic metals in groundwater. But the forces between
the molecules at the surfaces of microbes and minerals had never been
measured.
Now, a Virginia
Tech graduate student has invented a technique called biological force
microscopy and he and his major professor have used it to determine what
happens when Shewanella, a microorganism found in most soils, meets goethite,
the most important iron oxide in soils worldwide. The research provides
some of the first evidence of recognition between a living organism and
an inanimate object, such as a mineral.
The research
was featured in Science on May 18, 2001. Steven Lower, now an assistant
professor at the University of Maryland, College Park, invented the technique
while a Ph.D. student in geological
sciences at Virginia Tech. Michael
Hochella was his major professor.
Respiration
is the process by which living things, including humans, break down carbohydrates
to produce energy. Shewanella use oxygen to break down carbohydrates (breathe);
but, if there is no oxygen, the bacteria use iron3 (Fe III) to breathe.
This ability has a significant impact on the way minerals dissolve and
the movement of iron in the environment.
So the researchers
looked at Shewanella and goethite. “The bacteria transfer (carbohydrate)
electrons to the mineral. The addition of each electron breaks a bond
between atoms on the mineral’s surface and allows the goethite to
shed iron. The result can be iron shed into groundwater. Or, if a toxic
metal, such as lead or arsenic, is bound to the surface of the goethite,
these metals are also shed.”
Research to explain behavior in laboratory and field aided by wireless equipment, compatible programs
A $2.3-million
National Science Foundation grant to develop infrastructure in social
sciences will link research, software development, and web-based teaching
techniques developed by economists, anthropologists, political scientists,
and others working together on social science and management applications.
Virginia Tech is one of eight universities that will share the grant.
Catherine
Eckel, professor of economics at Virginia Tech, will develop a portable
wireless laboratory for conducting experiments in classrooms and at remote
sites. Such laboratories will allow for experiments at remote sites, such
as the Soviet Union or isolated cultures in Africa, and with populations
other than the usual college students. “We can expand the groups
we can study away from college students, which significantly enhances
the validity of our research,” Eckel said.
One part
of the grant proposal includes a library of programs for conducting interactive
decision-making exercises that people from different disciplines can run
on an Internet-based system. This will remedy the situation in which researchers
at different locations and from different disciplines have to “start
from scratch” because the software at each location does not cross
platforms.
Under this
grant, the researchers develop experiments to test the game theoretic
models. Game theory is applied in political science, management science,
and related fields, as well as in economics. Eckel and Rick Wilson of
Rice University, for example, are studying a single social signal —
facial expressions — to learn more about factors that influence interactions
between people in such situations as negotiations or financial transactions.
The researchers isolate facial features by showing stylized icons and
photographs so the participants have no other information. It is important
that the participants not know the people in the pictures, so a virtual
lab would allow use of facial expressions of people at another location.
A related
project will use the portable lab to implement decision-making exercises
designed to measure risk attitudes, time preferences, cooperation, and
other factors that may ultimately be useful in identifying at-risk children
in schools
Another project,
undertaken by Eckel and a team at Virginia Tech, is designed to extend
the educational use of these experiments to large classes. For example,
in a market game, students play the roles of buyers and sellers, and they
can watch the bids and offers prices converge to the price predicted by
supply and demand theory. By asking questions that highlight pressures
to raise or lower prices, the students can discover for themselves how
theoretical concepts, such as supply and demand, explain behavior.
Researchers are working to develop a plant-based diabetes treatment
Virginia
Tech biochemistry and biology researchers are exploring whether plants
can be engineered to produce a human enzyme to treat Type 2 diabetes.
If Glenda
Gillaspy’s research leads in the direction she expects, plants
will cheaply produce the human enzyme that is now painstakingly and expensively
synthesized to treat 16 million Americans suffering from Type 2 diabetes.
Gillaspy, assistant professor of biochemistry, and collaborator Cynthia
Gibas, assistant professor of biology, are laying the groundwork for what
is expected to be the creation of a transgenic plant that will produce
D-chiro inositol.
Gillaspy’s
previous work included manipulation of inositol synthesis genes in plants
to increase production of D-chiro inositol precursors. She will be using
information from the Arabidopsis plant, whose genome was totally decoded
last year.“This is the very beginning of a long process,” Gillaspy
said. “We’re looking into how plants and animals synthesize
this compound. Once we figure that out, we can look into how to make plants
produce it in large quantities.”
Tobacco is
likely to be the plant Gillaspy will try to manipulate to produce the
compound because its genes are relatively easy to work with and it produces
large amounts of material from which the compound can be extracted.
The lack
of D-chiro inositol causes Type 2 diabetes. The disease can be treated
by replacing the missing inositol through medication. “We are looking
to eventually generate this compound in large quantities,” Gillaspy
said. “We hope the compound produced by plants will have the same
properties as that produced in humans. At a deeper level, however, we
are seeking to understand why the synthesis of this compound changes the
signaling at the molecular level.”
The research
is being funded by a grant from Virginia’s Commonwealth Health Research
Board, whose funding is derived from stock and cash received by the state
from the conversion of Blue Cross and Blue Shield of Virginia from a mutual
insurance company to a stock corporation now known as Trigon.
Small streams important in controlling nitrogen
Streams are
not gutters that simply deliver nutrients to lakes, oceans and bays. Streams
are vibrant ecosystems, and the smallest streams remove as much as half
of the inorganic nitrogen that enters them, according to researchers from
more than a dozen institutions who studied streams from Puerto Rico to
Alaska over the course of two years.
The results
were reported in the April 6, 2001 issue of Science, in the article
“Control of Nitrogen Export from Watersheds by Headwater Streams”
by Bruce J. Peterson and W.M. Wollheim of the Marine Biological Laboratory
(MBL) in Woods Hole, Mass.; Patrick J. Mulholland of Oak Ridge National
Laboratory; Jack Webster and Maury Valett of Virginia Tech; Tech graduate
Jennifer Tank, now at the University of Notre Dame; and others.
Human activities,
such as fertilizer application and the burning of fossil fuels, result
in excess nitrogen entering streams, changing water quality downstream,
such as in the Chesapeake Bay or Gulf of Mexico. The approach to minimizing
nitrogen in these waterways has been mainly terrestrial, since the processes
responsible for nitrogen uptake and release in streams has been a black
box, says Webster, professor of biology at Virginia Tech. But an NSF-sponsored
workshop in 1995 identified models and a tracer that might be used to
develop a systematic approach.
A breakthrough
came when MBL chemists made it easier to measure the stable isotope N15
(nitrogen 15), making it a useful and economically feasible tracer. Meanwhile,
the scientists developed mathematical computer models of streams’
biological processes that made it possible to compare the nitrogen cycle
in different kinds of streams.
“The
bottom line is streams have an impact. They can remove as much as 50 percent
of the inorganic nitrogen. So anything we do to streams to modify them
will impact the nitrogen that reaches rivers, lakes, bays and oceans,”
says Webster. The finding could have important consequences for land-use
policies.
What happens
to the nitrogen that is removed from streams? The Science article reports
that some of the nitrogen is converted to nitrogen gas through denitrification
processes, and the rest becomes nutrition for algae, bacteria, and fungi,
which then become food for aquatic insects and fish. As the plant or organism
dies, the nitrogen can then end up as slowly decomposing materials that
settle in the stream or lake sediments, Webster says.
He explains
that plant life, particularly algae, is a very important nitrogen-user
in some streams — such as in Alaska and Arizona, where there are
few trees to block the sun. Alternatively, in forested streams, such as
those in Oregon and North Carolina, nitrogen is removed by fungi and bacteria,
which do not photosynthesize, but decompose dead organic material settled
on the stream bottom, also a food resource for some aquatic insects.
“The
smaller the stream, the more quickly nitrogen can be removed and the less
distance it will be transported down the stream,” Peterson says.
Thus, taking greater care to ensure that small streams can work effectively
to clean the water will reduce the overall nitrogen load that makes its
way into larger bodies of water. “It doesn’t mean that you can
ignore your sewage treatment plants, but if we can do better with our
small streams and do some restoration activities it’s going to have
some benefits,” he says. “What it means is that you have to
take care of the streams on the landscape.”
The research
was funded by the National Science Foundation with a $1.4 million grant,
plus the resources of each unit. “The collaboration was key,”
says Webster. “That was one of this project’s strengths.
Mullholland
is leading an effort to obtain funding for another large N15 tracer project
involving 72 streams. “The original streams were located in relatively
pristine areas — primarily national forests, some nature preserves,
and reservations. Next we would like to include streams in agricultural
and urban landscapes” Webster says.
