By Richard Acello
Small Times Correspondent
Feb. 8, 2002 — University of California, Davis nanoscientist Alexandra Navrotsky recalls watching the light under her grandfather’s door. He was a civil engineer and young Navrotsky wondered about the “curiosities that keep lights burning after midnight.”
Her own curiosities about the nature of the earth recently led the Philadelphia-based Franklin Institute to award Navrotsky the prestigious Benjamin Franklin Medal in Earth Science for her work on thermochemistry, high pressure materials and nanomaterials. The Franklin medals have been described as “American Nobels.” In fact, 98 Franklin laureates have gone on to capture Nobels, including Marie Curie and
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| Alexandra Navrotsky is studying Nanoparticles in the search for a “geoengineering solution” to global climate change. It’s theoretically possible, but “the stakes are very high,” says a fellow scientist. |
Navrotsky’s research focuses on nanomaterials composed of small particles a few atoms in diameter. Compared to so-called bulk materials, nanomaterials have a high surface area for their volume so that nearly all of the atoms are on the surface. Navrotsky studies how the chemical and electrical properties in nanomaterials differ from larger structures and is a pioneer in the developing field of nanogeoscience.
“In the geological realm, nanomaterials are important to understanding where all reaction happens in the earth,” she says.
For example, she explains, the behavior of nanosize dust may hold clues in understanding global climate change, the movement of pollutants in the atmosphere and the weathering of minerals.
At UC Davis, Navrotsky holds a chair in mathematical and physical science, but divides her time between four departments: chemistry; chemical engineering and materials science; geology; and land, air, and water resources. She heads the university’s initiative on Nanophases in the Environment, Agriculture and Technology (NEAT), which includes 20 UC Davis faculty from a variety of departments. NEAT is funded in part by a grant from the National Science Foundation (NSF).
“Alex is amazing. She’s a powerhouse. There’s a lot of uncharted area of discovery in nanoscience,” says Professor Tony Wexler, a NEAT colleague whose specialties include mechanical and aerospace engineering, civil and environmental engineering and land, air and water resources.
Wexler’s NEAT research centers on understanding the role of nanoparticles in global climate change and their effect on everything from agriculture to the quality of air in pharmaceutical factories.
Nanoparticles, also called aerosol particles, are suspended in the air in varying quantities around the globe and are generally thought to be a force for global cooling. Carbon dioxide, on the other hand, is generally thought to be a force toward global warming, and is distributed evenly over the globe. “The spatial distribution of the heating and cooling effects is different than they used to be,” Wexler says. “And our understanding of these effects is very crude.”
A so-called “geoengineering solution” to global climate change is theoretically possible, but “the stakes are very high,” Wexler says.
Devices that measure aerosol particles have been commercially developed by companies such as St. Paul, Minn.-based TSI Inc., and Rupprecht & Patashnick Co. Inc., based in Albany, N.Y.
But, Wexler says, “We (UC Davis) are the only people in the world who can give you the size and composition of nanoparticles down to 10 to 20 nanometers.” Wexler says he has been in contact with parties that want to commercialize the research, but can’t disclose them due to patent considerations.
NEAT’s studies into nanoparticles and their effect on global climate change has obvious implications for agriculture, but also for clean rooms, pharmaceutical factories producing aerosol powders — where workers could be exposed to the drugs they are producing — and in other occupational safety and health issues. NEAT’s work could also resonate in areas such as energy pricing and conservation.
The NSF is also funding Navrotsky’s work as a principal investigator for the Center for High Pressure Research, charged with studying the deep interior of the Earth and other planets.
Navrotsky has written more than 200 papers centered around the question, “Why does a given structure form for a specific composition, pressure and temperature?” The answer lies at the intersection of thermodynamic properties, material structure and chemical bonding.
Of her methodology, she says, “You start reading things, and your idea of what’s exciting keeps changing. It’s always evolutionary.”
Her laboratory is a 5,000-square-foot space equipped with high-temperature calorimeters that measure the thermodynamic reactions, or heat given off or absorbed, when a material is exposed to a catalyst. This is done by heating the material to its melting point and when it dissolves, or changes from solid to liquid, measuring the difference in temperature.
The lab is populated by a research group of 25 with an annual budget of about $1 million. Though many of her friends are scientists, in explaining her work to lay people she might say, “I study how atoms love each other and how it affects the universe,” or simply “I count calories for a living.”
“She’s driven, has a great sense of humor, and her enthusiasm is contagious,” says Susan Kauzlarich, a professor of chemistry at UC Davis and a colleague in the NEAT program. Because of the interdisciplinary nature of NEAT with about 20 faculty, meetings of the entire group are rare, Kauzlarich says, but the group stays in touch through seminars, and of course, by e-mail. “We’re very proud of her,” says Kauzlarich.
Navrotsky traces her passion for geology to a childhood fascination with nature. “If the weather was nice, we’d go to our summer place outside of New York City,” she recalls, “and in the winter, we’d go to museums. I don’t know when I knew I wanted to be a scientist, but by the time I formed the question, I already had the answer.”
While her research is necessarily abstract, it’s not unusual for a colleague to contact her looking for advice on how to build a better light bulb. In fact, she says, her thermodynamic calculations apply to thermal technologies used by NASA. “Materials compatibility is critical to the performance of just about anything,” she says. “You don’t want John Q. Public yelling at you because your device failed in a humid environment.”
Ultimately, she hopes the emerging field of nanogeoscience will shed light on the movement of air and water pollution. Beyond that, she believes that understanding of reactions at the nanoscale could unlock mysteries about the origin of life.
“From an atom to a galaxy,” she reflects. “That’s what makes it fun. I want to understand the universe: don’t we all?”
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