SSRL Science Highlights Archive

Approximately 1,700 scientists visit SSRL annually to conduct experiments in broad disciplines including life sciences, materials, environmental science, and accelerator physics. Science highlights featured here and in our monthly newsletter, Headlines, increase the visibility of user science as well as the important contribution of SSRL in facilitating basic and applied scientific research. Many of these scientific highlights have been included in reports to funding agencies and have been picked up by other media. Users are strongly encouraged to contact us when exciting results are about to be published. We can work with users and the SLAC Office of Communication to develop the story and to communicate user research findings to a much broader audience. Visit SSRL Publications for a list of the hundreds of SSRL-related scientific papers published annually. Contact us to add your most recent publications to this collection.

SCIENCE HIGHLIGHT BANNER IMAGES

July 2004
Anneli Munkholm (Lumileds Lighting), Sean Brennan (SSRL)
Figure 1.

New evidence is overturning the assumption that the thermal oxide grown on single crystal silicon is completely amorphous. SSRL researchers Anneli Munkholm (now at Lumileds Lighting) and Sean Brennan recently published work in Physical Review Letters showing that there is residual order within the oxide. The thermal oxide film on silicon has been studied extensively for decades because these oxides form the basis of most of the integrated circuits used in modern electronics. The new results have implications for theoretical models of the oxidation process.

X-ray scattering
June 2004
Thiang Yian Wong, Robert Schwarzenbacher, Robert C. Liddington
Figure 1.

Anthrax makes a deadly cocktail of three toxin proteins that flood the bloodstream, leading to rapid death if the infection is not diagnosed and treated in its early stages. Even antibiotic treatments can fail when the Anthrax bacterium, Bacillus anthracis, has already produced lethal levels of toxins. The poisonous protein called Lethal Factor (LF) rapidly blocks signals to recruit immune cells to fight the infection. Another enzyme Edema Factor (EF) causes the release of fluid into the lungs and is deadly on its own. 

Macromolecular Crystallography
BL7-1, BL9-1
May 2004
I. Tudosa, H. C. Siegmann, J. Stöhr
Figure 1.

Two important goals of technology are: smaller and faster. In line with this goal the 50 billion dollar per year magnetic recording industry has long wondered where it would run into obstacles set by fundamental physical principles. The basic questions concern the lateral sizes at which the magnetic domains that define the "1" and "0" bits become unstable and whether there is a speed limit for the writing process of the bits.

April 2004
Nathaniel J. Cosper, David L. Bienvenue, Jacob E. Shokes, Danuta M. Gilner, Takashi Tsukamoto, Robert A. Scott, Richard C. Holz
Figure 1.

Antibiotics and the bacteria they attack are engaged in a constant race to out-evolve one another. An antibiotic is effective against specific bacteria only so long before the random mutations that all bacteria undergo make them resistant to that particular drug. Recently, scientists from the University of Georgia, Utah State University, and Guilford Pharmaceuticals carried out studies at SSRL that could enable drug designers to pull ahead, at least for a while, by developing a new class of antibiotics.

BL9-3
April 2004
Figure 1.

In ice, each water molecule is surrounding by 4 other molecules in a tetrahedral arrangement (left). The new result on liquid water shows that the molecules are connected only with 2 others. This implies that most molecules are arranged in strongly hydrogen bonded rings (middle) or chains (right) embedded in a disordered clusternetwork connected mainly by weak hydrogen bonds. The oxygen atoms are red and the hydrogen atoms grey in the water (H2O) molecules.

X-ray Absorption Spectroscopy, X-ray RAMAN spectroscopy
March 2004
John M. Zachara, Calvin C. Ainsworth, Gordon E. Brown, Jr., Jeffrey G. Catalano
Table 1.

Toxic and carcinogenic chromate (hexavalent chromium as CrO42-) has contaminated the groundwater in Hanford, Washington. At Hanford, hexavalent chromium was used in the industrial process to recover plutonium from irradiated nuclear fuels. The resulting high-level waste corroded its storage tanks and leaked into the desert subsoils. Plumes of contaminated groundwater reaching the Columbia River pose a risk to spawning salmon.

BL4-3, BL11-2
February 2004
David A. Bushnell, Kenneth D. Westover, Ralph E. Davis, Roger D. Kornberg
Figure 1.

Professor Roger D. Kornberg and his group in the Stanford University School of Medicine have devoted more than 20 years to the study of the process by which genetic information encoded in all living things by DNA is processed into a message (a process called transcription that produces messenger RNA) that then directs the synthesis of proteins. A breakthrough paper detailing the structures of the core RNA Polymerase II protein was published in Science in April 2000 and followed by two more papers in Science a year later.

Macromolecular Crystallography
BL9-2, BL11-1
February 2004
P. Emma, K. Bane, M. Cornacchia, Z. Huang, H. Schlarb, D. Walz
Figure 1.

Computer simulations have shown that by using a cleverly placed piece of slotted foil, the Linac Coherent Light Source (LCLS) will be able to produce brilliant x-ray pulses that are extremely short, a few femtoseconds (a femtosecond is a quadrillionth of a second), in duration. This pulse length, which is a factor of more than 200 times shorter than the LCLS baseline design, will dramatically increase LCLS' x-ray time resolution, giving scientists the ability to study the movement of matter at atomic scales and accessing the structural changes occurring in the making or breaking of chemical bonds.

January 2004
Kottayil I. Varughese, Zaverio M. Ruggeri, Reha Celikel
Figure 1.

When a blood vessel is cut, the body activates a repair mechanism that eventually seals the cut and prevents further blood loss. This life saving process becomes life threatening when clots form inside a functional blood vessel. Arrest of bleeding works through platelet adhesion and thrombin-induced fibrin formation at the site of injury. In order for the platelets to stick to the injured tissues and to each other, they need to be activated. Thrombin is an essential protease (a type of enzyme) that activates platelets and forms blood clots in response to vascular injury.

Macromolecular Crystallography
BL9-2
December 2003
Olivier Pelletier, Elena Pokidysheva, Linda S. Hirst, Nate Bouxsein, Youli Li, Cyrus R. Safinya
Figure 1.

With the completion of the Human Genome Project and the emerging proteomics era, the biosciences community is beginning the daunting task of understanding the structures and the structure-function relations of collections of interacting proteins. Cellular activity, which is tightly regulated, often results from protein-protein and protein-nucleic acid interactions, leading to the formation of large assemblies of biomolecules for distinct functions. Examples include DNA condensation during the cell cycle, and bundle and network formation of filamentous actin proteins in cell attachment, motility, and cytokinesis.

BL4-2, BL10-2

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