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In this issue:
Dino Team Returns to SSRL
Science Today: The Structure of a Coated Gold Nanoparticle
NASA Recognizes SLAC's Gunther Haller and Martin Nordby

SLAC Today

Thursday - January 10, 2008

Paleontologist Peter Larson with the 72-million-year-old forearm of a duck-billed dinosaur named "Leonardo." Traces of the scales that covered the skin are still visible.

Dino Team Returns to SSRL

The experimental hutches at the Stanford Synchrotron Radiation Laboratory are well familiar with a macabre tide of materials brought in for close investigation. A recent tally includes ancient parchment texts, human brain tissue, fly heads and fish embryos, to name only a few.

Last April, a team of researchers arrived with a menagerie of fossilized dinosaur parts for a pioneering first-go at using x-rays to reveal traces of soft tissue embedded in the stone fragments. In December, just before the holiday break, the dino crew returned to SLAC with an expanded team for another round of investigations. What they're learning is revolutionizing the science of paleontology.

"This is a whole new area of our science that no one has ever done before," said Peter Larson, a paleontologist from the Black Hills Institute and one of the team leaders. "It's sort of like what Columbus and the earlier explorers learned to do… we're testing the waters to find out how we can improve our methods." Read more...

(Daily Column - Science Today)

The Structure of a Coated Gold Nanoparticle

(Picture - crystal structure)
X-ray crystal structure determination of Au102(p-MBA)44 nanoparticle. (Click on image for larger version.)

A team of scientists, working in part at the Stanford Synchrotron Radiation Laboratory's crystallography beam lines and led by Stanford Professor Roger Kornberg, has determined for the first time the atomic structure (at 1.1 Å resolution) of a thiol-covered gold nanoparticle, a discovery with potential for a range of applications from biosensors to nanotransistors. The results were published in the October 19 issue of Science.

Gold is an appealing metal for many uses because of its softness, optical and electrical properties, and because it does not oxidize. However, a plain gold surface may not be compatible with certain applications, so scientists are experimenting with gold clusters and surfaces coated with organic molecules, such as thiols. The organic layer, which self-assembles in a geometric array on the gold surface, changes the gold's chemistry. For example, coating gold can make it biocompatible for implantation into living organisms. Another possible application is to make self-lubricating materials.

Synthesizing well-defined thiol-coated gold nanoclusters is a challenging process. This thiol-coated structure, confirmed from the screening of 15 separate crystals derived from multiple preparations, shows homogeneous clusters of 102 gold atoms surrounded by 44 molecules of p-mercaptobenzoic acid. The central gold atoms are packed with decahedral symmetry, with additional layers of gold atoms in unexpected geometries. The cluster is coated by a thiol monolayer, with each sulfur bridging between two gold atoms, and with stabilization of the coat provided through several types of interactions between the thiol molecules. This structure will assist in the understanding of principles of nano-core assembly and the theoretical basis of gold-thiol interactions.

Read the full scientific highlight...

NASA Recognizes SLAC's Gunther Haller and Martin Nordby

(Photo - Gunther Haller and Martin Nordby)
Goddard Space Flight Center Director Edward J. Weiler presents the award to Gunther Haller and Martin Nordby. (Click on image for larger version.)

The Gamma-ray Large Area Space Telescope (GLAST) Observatory is scheduled to launch in May of this year, but the design of the Large Array Telescope (LAT) instrument has already earned NASA recognition awards for SLAC's Gunther Haller and Martin Nordby for their contributions to the program. Haller and Nordby were presented with the Goddard Space Flight Center Engineering Achievement Awards at a ceremony on December 11, 2007. Of the nine recipients for this year’s awards, Haller and Nordby were the only two not employed by NASA.

The Engineering Achievement Award recognizes excellence in engineering support of science as demonstrated by innovative engineering solutions to technological problems.

"These awards from NASA to recognize Martin and Gunther for outstanding leadership and engineering achievement represent significant accomplishment," said Project Manager Ken Fouts, who pointed out that GLAST is the first large-scale joint project between NASA and the Department Of Energy.

Nordby said the award was an honor, and emphasized that the recognition is indicative of the commitment of everyone involved in the project.

"This is a sign of SLAC's expertise and achievement," Haller agreed. "This isn't just the two of us."

GLAST will observe physical processes far beyond the capabilities of earthbound laboratories. GLAST's main instrument, the LAT—which was designed and integrated at SLAC—operates like a particle detector rather than a conventional telescope. It is 30 times more sensitive (and even more so at higher energies) than previous missions, enabling it to detect thousands of new gamma-ray sources while extending knowledge of previously unidentified sources.

Haller sustained management and technical leadership for all the electronics, data-acquisition and flight software systems, while Nordby's responsibility has been the management and technical leadership for the mechanical systems.


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