Stanford Synchrotron Radiation Lightsource

As part of a larger, DOE-funded investigation into bioremediation of uranium in contaminated aquifers, a group of SSRL scientists made a surprising discovery about how uranium ions behave in the environment. In addition to overturning current scientific models, this research will lead to more efficient, less costly methods for uranium cleanup and mining.

Recent work at SSRL has helped reveal a previously unrecognized wealth of bromine chemistry in the environment, where bromine in seawater has long been thought to exist as inorganic bromide, while bromides in soil were considered so unreactive that they've routinely been used as a hydrological tracer.

The reality bromine chemistry in the environment is much more complex. X-ray absorption spectroscopic (XAS) studies conducted by Leri, et al. at SSRL Beam Lines 2-3 and 4-3, as well as at the ALS and NSLS, reveal a complicated association between bromine and organic carbon in both sea water and soil.

Scientists have discovered a gene for a protein that regulates the cellular response to copper in the bacterium that causes tuberculosis. These findings, reported in the January issue of Nature Chemical Biology, explain how a wide variety of bacteria control copper concentrations within their cells, and this understanding could lead to new treatments for tuberculosis.

The FeFe-hydrogenases are of great interest because they can catalyze both the forward and reversed dihydrogen uptake/evolution reactions. Under optimal conditions a single molecule of FeFe-hydrogenase can produce approximately 9000 molecules of hydrogen per second. This translates into a theoretical capacity for refueling the hydrogen tank of the Space Shuttle within 30 minutes. Thus, hydrogenases are considered as desirable biological targets for hydrogen-based energy production and utilization technologies.

SSRL and Stanford scientists, in collaboration with a team from UC Irvine, have gotten the first look into how the metal active center of an enzyme that is largely responsible for fertilizing plants is assembled. This enzyme, which is called nitrogenase, certain bacteria employ to turn nitrogen from the air into a form that plants can use for healthy growth. In contrast to the enzymatic reaction, manufacturing nitrogen fertilizer chemically requires extreme pressures and temperatures and thus huge amounts of energy.

Porous nanoscale materials often have useful properties because of their proportionally large surface areas. Now, UCLA scientists have devised a way to make porous germanium, a semiconductor used in fiber optics and electrical components. This discovery means that nanoporous materials could soon be used to develop new kinds of solar cells or highly sensitive electronic sensors.

The toxicity of arsenic is widely known, but perhaps less widely appreciated is that it's the level of toxicity critically depends on the chemical form. The fern Pteris vittata, is one of a small group of plants that actively accumulates to a startling degree - an arsenic hyperaccumuatlor. P. vittata absorbs arsenic from soil, typically present as the relatively benign arsenate, and changes its chemical form to arsenite, which is one of the more toxic kinds of arsenic. The plant thrives on this toxic regimen, and it most likely does this to defends itself from hungry herbivores. The ability of P. vittata to take up arsenic has generated much excitement because of potential applications for environmental cleanup of drinking water and of contaminated sites.

Fiber optic communication relies on the strength of a signal of light to deliver information, but over long distances that signal becomes dim and can lose its integrity. Amplifying the signal along the way can decrease signal loss, and scientists have been searching for new materials to build photonic signal amplifiers that are inexpensive and easily mass produced. Now, researchers from UCLA, working in part at the Stanford Synchrotron Radiation Laboratory Beam Line 11-2, have demonstrated how to deposit a special thin film with photoluminescent erbium (Er) onto silicon wafers. This technique could lead to the development of miniaturized optical amplifiers integrated with microchips for their incorporation into communications hardware.

Uranium contamination is a major concern at Department of Energy sites and decommissioned mining and ore processing facilities around the U.S. Migration of uranium has contaminated ground water in several locations, and the threat remains for further contamination unless costly measures are taken to isolate the contaminates and stop their spread.

Uranium (U) contamination of ground and surface water is a serious problem in many parts of the world. Agricultural practices, mining, and nuclear weapons production have resulted in elevated levels of this heavy metal at a variety of locations, which threatens human health by seeping into groundwater and dispersing over large areas.