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July/August 2002

The Laboratory
in the News

Commentary by
C. K. Chou

The Outlook Is for Warming, with Measurable Local Effects

How Metals Fail

Converting Data to Decisions

Knowing the Enemy, Knowing the Threat

Patents

Awards

 

The Laboratory
in the News

Interim measures to save the Salton Sea
California has long been using more than its allotment of Colorado River water and now is under mandate to reduce that usage. One way the state plans to achieve the reduction is to save on agricultural water usage.
In the Imperial Valley agricultural region of southern California where such saving is being proposed, one concern has to do with the effects of conservation on the aquatic ecosystem at the Salton Sea, which depends on agricultural runoff to keep its salt levels down. If runoff were decreased, dilution would decrease, the Salton Sea’s salt levels would rise, its fish would die, and the migratory birds—for which the sea is a key stop—would have no food.
At the request of California Representative Duncan L. Hunter, Livermore researchers conducted studies to come up with recommendations on how to stave off increased salinity in the Salton Sea. The researchers recommended that irrigation canal water that has seeped into the ground, on the order of some 145,000,000 cubic meters per year, be reclaimed and fed into the Salton Sea. They also proposed the construction of evaporation ponds to extract salt from the sea. And they are looking at ways to use geothermal energy to desalinate Salton Sea water and then pump it back in.
Dave Layton, division leader for the Laboratory’s Health and Ecological Assessment Division and one of the researchers on this project, said that the proposal requires more study and drilling of test wells to see if it is worthwhile to pump water into the Salton Sea. He added, “In any event, the use of groundwater would only constitute an interim measure and would have to be linked to management actions regarding other potential mitigation measures for the Salton Sea.”
Contact: David Layton (925) 422-0918 (layton1@llnl.gov).

Bioterrorism detectors also protect food supplies
Livermore biomedical scientist Paula McCready told her audience at a meeting of the American Society for Microbiology last May that “The tools we use to develop DNA signatures for the detection of bioterrorist agents could also be used to search out food-borne pathogens.”
DNA signatures, the regions of DNA unique to specific organisms, are being identified much more quickly as a result of advances in DNA sequencing. What used to take years to find has been condensed to a period of weeks or months. This is important because now DNA signatures can be quickly developed for new strains of pathogens.
And using those signatures in another application—to find the bacteria that cause food poisoning—allows laboratories to more rapidly identify their presence in food and in the environment. The diagnostic tests to identify such food bacteria have been lessened from hours and days to under one hour because scientists no longer need to culture and prepare samples before analysis.
“We can tailor our tests to distinguish harmful forms of different organisms from the benign forms,” says McCready. Among the bacteria that could be identified, according to her, are Camphylobacter, a bacterium present in undercooked chicken, or Salmonella, a bacterium that can be found in eggs, juice, fruit, or vegetables.
Livermore researchers and other biomedical scientists have developed highly accurate DNA signatures for the bacteria that cause plague and anthrax as well as for other organisms. This work has been performed in collaboration with Los Alamos National Laboratory researchers and the Bioterrorism Rapid Response and Advanced Technology Laboratory of the Centers for Disease Control and Prevention in Atlanta.
Contact: Paula McCready (925) 422-5721 (mccready2@llnl.gov).

Osmium has it over diamonds in stiffness
Stiffness is the measure of a material’s compressibility. The stiffest materials also tend to be the hardest ones. But in the case of diamonds and osmium, the former is still the hardest, even though the latter is stiffer. This surprising information was discovered by Laboratory physicist Hyunchae Cynn, who decided to look at osmium because its stiffness had never been accurately measured. “It caught my eye,” he said.
When the bulk modulus—resistance to compression—of osmium turned out to be higher than that of diamond, no one really believed it. So Cynn crushed the osmium under 60 gigapascals of pressure in a diamond-anvil device and looked at the resulting x-ray diffraction patterns to determine the spacing between crushed osmium atoms. The data gave osmium a bulk modulus of 462 gigapascals compared with the 443 gigapascals for diamond.
Because osmium is so different from other materials with high bulk modulus, Cynn says that researchers should take a closer look at metals and other materials to see if they might have missed discovering any properties simply because the properties were unexpected.
Contact: Hyunchae Cynn (952) 422-3432 (cynn1@llnl.gov).


 


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UCRL-52000-02-7/8 | July 12, 2002