News from the Department of Energy's Oak Ridge National Laboratory, February 2008

Microbilogy - A gut feeling . . .

Bacteria cells outnumber human cells in the average healthy human body by a factor of almost ten. Now researchers are asking if those resident microorganisms play a larger role in who we are than previously thought. ORNL researchers are joining an international collaboration to learn more about the role microorganisms play in, for example, the digestive system and how disruptions in the symbiotic balance in "gut microflora" might control the transition from healthy to disease conditions. ORNL's capabilities in mass spectroscopy offers researchers new and powerful tools for probing the extremely complex relationships between the microbiome and their human hosts.

Ecology - Nature's way . . .

Small streams disrupted by military training activities or commercial development can be restored with simple and inexpensive measures, according to findings of a group headed by Pat Mulholland of Oak Ridge National Laboratory. Researchers from ORNL and Auburn University learned that streams can be adversely affected even if as little as 10 percent of the watershed is disturbed. In their study, conducted at Fort Benning, Ga., the researchers found that revegetating drainage ditches that carry water only during storms and adding dead trees and woody debris to stream channels helped trap smaller organic materials and improve the habitat for stream organisms, including fish. "This project has provided the military with an improved understanding of its effects on streams and a possible approach for mitigating some of those effects," Mulholland said. The project was named Sustainable Infrastructure Project of the Year by the Strategic Environmental Research and Development Program, which funded the work.

Nanoscience - Atom-scale switch . . .

ORNL researchers have discovered a carbon nanotube-based system that functions like an atom-scale switch. Their approach is to perform first-principles calculations on positioning a molecule inside a carbon nanotube to affect the electronic current flowing across it. The result is an electrical gate at the molecular level: In one position, the molecular gate is open, allowing current through; in another position, the gate is closed, blocking the current. In a silicon chip, the gate is a silicon oxide barrier within the structure of the chip. In the ORNL model, the gate is a short molecule - encapsulated inside the carbon nanotube - that is about one nanometer in size, or three orders of magnitude smaller than a silicon chip.

Fusion - Lassoing turbulence . . .

Fusion power is a holy grail of our energy future, promising eventually to provide cheap, plentiful electricity with a minimum of environmental concerns and no greenhouse gases.

Before it does, however, scientists must learn to control and contain an ionized gas hotter than the sun. Theoretical physicists from General Atomics are using ORNL's Phoenix supercomputer to understand turbulence that leaches energy from fusion reactors. In particular, they are focusing on the interaction between eddies created by gyrating electrons and much larger eddies created by gyrating ions. The answers they provide will be an important step toward an energy revolution.

Climate - Improving projections . . .

A new data mining tool developed by Forrest Hoffman and colleagues could lead to a better understanding of Earth's climate systems and to more accurate models. Using a novel cluster analysis technique to classify and group data, the researchers are able to take extract and compare relevant patterns from enormous datasets. For this study, researchers used data for the Southern Great Plains Atmospheric Radiation Measurement (ARM) site in Lamont, Okla., and projections from the National Center for Atmospheric Research's Community Climate System Model. One finding of note is that the model fails to capture an observed atmospheric state characterized by very low wind shear under high humidity and temperature conditions at the ARM site. Others involved in this project are Salil Mahajan of Texas A&M University, Sigurd Christensen and Richard Mills of ORNL and Bill Hargrove of the U.S. Department of Agriculture Forest Service. The research was funded by the Department of Energy's Office of Biological and Environmental Research, Climate Change Research Division.