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Safer Plutonium Storage
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This issue...
News in Brief
View from the Inside
Safer Plutonium Storage
Crazy Physics
Working
Science
People
About
Subscribe Free
This issue...
News in Brief
View from the Inside
Safer Plutonium Storage
Crazy Physics
Working Science
People
About
Subscribe Free
This issue...
News in Brief
View from the Inside
Safer Plutonium Storage
Crazy Physics
Working Science
People
About
Subscribe Free
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News in Brief
Nanotechnology: Information by the Molecule
By altering a thin film, it may soon be possible to store a million times more electronic information in the same amount of space. Researchers Hongjun Gao, Karl Sohlberg, and Stephen Pennycook of Oak Ridge National Laboratory and collaborators from the Beijing Laboratory for Vacuum Physics concluded that this was possible after disordering and re-ordering tiny regions of an organic and graphite film so thin that 40,000 layers would be only as thick as a sheet of paper. The researchers exposed the film to voltage pulses with a scanning tunneling microscope, which changed the nanometer-sized regions from crystalline to disordered and increased their electrical conductivity by 10,000 times. As a result, each bit of information is not much bigger than a single molecule of the film. For the first time, the researchers have demonstrated that information can be written and erased in a film at or near the single molecule limit.
This research is supported by the Division of Materials Sciences and Engineering in the Office of Basic Energy Sciences. For more information, see the researchers' recent paper published in the Physical Review Letters, Vol 84, Issue 8, pg. 1780.
Contact: Hongjun Gao, hjgao@solid.ssd.ornl.gov , (865) 574-5507; Karl W. Sohlberg, sohlbergk@ornl.gov, (865) 574-7032; Stephen J. Pennycook, pennycooksj@ornl.gov, (865) 574-5504.
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A Job-Sharing Enzyme
When the entire genome sequences were deduced for two methane-producing bacteria, Methanococcus jannaschii and Methanobacterium thermoautotrophicum, scientists were puzzled to find no genes that encoded the transfer RNA (tRNA) synthetase (enzyme) responsible for adding the amino acid cysteine, which is essential for protein synthesis. Their puzzlement arose because all living organisms use this common mechanism for translating genetic instructions from DNA blueprints into the proteins that carry out the biochemical functions within a cell. These proteins are synthesized from 20 different amino acid building blocks, each having a different and specific tRNA enzyme to catalyze its addition to the growing protein.
Dieter Söll and colleagues at Yale University recently presented an answer to this biological conundrum in the January 21 issue of the Science. They demonstrated that the enzymatic activity for synthesizing cysteine does exist in these bacterial species, but the gene actually encoded a tRNA enzyme that synthesizes the amino acids, proline and cysteine. This represents a unique biological circumstance in which a single tRNA enzyme catalyzes the attachment of two different amino acids. This job-sharing aminoacyl-tRNA enzyme may turn out to be a "missing link" in the evidence of the evolution of these enzymes. This research is supported by the Office of Basic Energy Sciences/Energy Biosciences program.
Contact: Dieter Söll, Yale University, soll@trna.chem.yale.edu
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Faster-Than-Ever DNA Sequencing
Capillary electrophoresis for sequencing DNA is one of the new technologies that have greatly accelerated the progress of the Human Genome Project. This technology has been able to determine 500 to 800 bases in a running time of a few hours, or extended sequences of 1000 or more bases with running times of 10 to 12 hours. However, Barry Karger and his research group at Northeastern University in Boston have found a way to sequence up to 1300 bases in two hours. (Click on graphic to enlarge.)
Karger and his research group demonstrated that they could combine long read lengths with short run times that would simultaneously reduce the cost and improve the reliability of determining the sequence of long strands of DNA. This was accomplished by optimizing the electric field strength and temperature, changing the composition of the linear polyacrylamide solution used to fill the capillary, and adding specific rules for low peak resolutions to the expert system software for base calling. The research was done in collaboration with Annelise Barron and her research group at Northwestern University in Evanston, Illinois. Details of their research were published in Analytical Chemistry 2000, 72, 1045-1052. Both groups were funded by the Biological and Environmental Research Genome Instrumentation Research Program of the Office of Biological and Environmental Research.
Related technical advances were presented at the February, 2000 DOE Human Genome Program Workshop with abstracts online at http://www.ornl.gov/hgmis/publicat/00santa/
Contact: Barry Karger, Northeastern University, barry.karger@neu.edu.
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NERSC Takes First Step Toward 3 Teraflop Computing
The DOE's National Energy Research Scientific Computing Center (NERSC) has completed Phase I of a two-phase plan to provide computing capability of 3 trillion calculations per second. The new IBM RS/6000 SP system is now ready for full use by researchers across the nation.
Phase I consisted of the installation and testing of the RS/6000 SP. The system has a peak performance of 410 gigaflops, or 410 billion calculations per second.
The Phase II system will be installed by December 2000 in Berkeley Lab's new scientific facility, which is currently under construction in Oakland, California. It will have a peak performance capability of more than 3 teraflops, or 3 trillion calculations per second.
While the theoretical peak performance of supercomputers can be amazingly fast, that capability does not always represent real-world computing. NERSC is working with IBM to develop and implement ways to make large-scale systems effective platforms for scientific discovery. To ensure that the new IBM RS/6000 SP system is well suited to the scientific workaday world, NERSC and IBM developed an Effective System Performance (ESP) benchmark for the new computer. This set of tests will measure how well it delivers scientific work under a realistic workload.
This program is supported by the Office of Advanced Scientific Computing. For more information about the IBM RS/6000, see Berkeley Lab Research News. For information about NERSC, visit the NERSC website.
Contact: Bill Kramer, NERSC, wtkramer@lbl.gov
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National Medal of Science Winner
Professor Emeritus James Cronin, University of Chicago, is one of 12 researchers named by President Clinton to receive the 1999 National Medal of Science. The medal is presented yearly to honor the discoveries and lifetime achievements of the Nation's top scientists. Cronin received the award for fundamental contributions to the fields of elementary particle physics and astrophysics, and as a leader in creating an international effort to determine the unknown origins of very high energy cosmic rays. The medal was presented on March 14 at the White House. Cronin's research is supported by SC's Office of High Energy Physics.
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More Science News
The Office of Science (SC) website has recently had a complete makeover. The front page includes late-breaking science news and feature stories about research supported by SC. The news and features link to the source of the information on the website of the lab or university where the research originated. News and features are updated on a regular basis.
Icons across the top of the page represent links to useful science information resources. For example, the camera takes you on a photo tour of any national laboratory you choose, and the book takes you to PubScience, a new database you can use to search scientific literature.
The U.S. map icon opens an interactive, color-coded map showing names and locations of all the DOE national laboratories, as well as other DOE facilities and university-affiliated programs supported by the Office of Science, all of which are linked directly to their websites.
Improved mouseover-style navigation allows you to access specific departments and programs within the SC divisions. See the new Office of Science website at http://www.science.doe.gov.
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