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

November 2006
H. Chapman, J. Hajdu
Figure 1.

Scientists have for the first time used an extremely short and intense coherent soft x-ray laser pulse to successfully obtain a high-resolution image of a nano-scale object before the sample was destroyed by the energy impact of the pulse. The experiment, conducted at Deutsches Elektronen-Synchrotron (DESY) in Hamburg by a collaboration that included researchers from the Photon Science Directorate at SLAC, also set a speed record of 25 femtoseconds for the duration of the x-ray pulse used to acquire the image. The results are published in the November 12 online edition and the December printed edition of Nature Physics.

X-ray diffraction
November 2006
J. Yano, V. Yachandra
Figure 1.

Billions of years ago, primitive bacteria developed a way to harness sunlight to split water molecules into protons, electrons and oxygen-the cornerstone of photosynthesis. Now, a team of scientists has taken a major step toward understanding this process by deriving the precise structure of the catalytic metal-cluster center containing four manganese atoms and one calcium atom (Mn4Ca) that drives this water-splitting reaction. This catalytic center resides in a large protein complex, called photosystem II, found in plants, green algae, and cyanobacteria. The international team was led by scientists from LBNL, and includes scientists from Germany's Technical and Free Universities in Berlin, the Max Planck Institute in Mülheim, and from SSRL.

X-ray Absorption Spectroscopy
BL9-3
October 2006
Samuel M. Webb, Bradley M. Tebo, John Bargar
Figure 1.

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.

X-ray Absorption Spectroscopy
October 2006
Matthew Ginder-Vogel, Wei-Min Wu, Jack Carley, Phillip Jardine, Scott Fendorf, Craig Criddle
Figure 1.

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.

BL11-2
September 2006
Figure 1.

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.

BL11-2
September 2006
Ingrid Pickering
Figure 1.

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.

X-ray Absorption Spectroscopy
BL9-3
August 2006
Monika Martick, William G. Scott
Figure 1.

Genes, which are made of nucleic acids (DNA or RNA) contain the instructions for how to make proteins, but still enzymes made of proteins are needed to replGenes, which are made of nucleic acids (DNA or RNA) contain the instructions for how to make proteins, but still enzymes made of proteins are needed to replicate the genes. This paradox was addressed ~20 years ago with the realization that some kinds of RNA can act as enzymes. These RNA enzymes, or ribozymes, are accordingly made of the genetic RNA material, but they act as chemical catalysts. This means that ribozymes would have enabled the first self-replicating molecules, also made of RNA, to copy themselves.

Macromolecular Crystallography
BL1-5
July 2006
Serena DeBeer George, John F. Berry, Eckhard Bill, Eberhard Bothe, Bernd Mienert, Frank Neese, Frank Neese
Figure 1.

Chemists have synthesized and characterized a new, highly reactive form of iron that promises to deepen our understanding of this important element. Iron is found in abundance in the natural world, and in its ionized form plays a crucial role in virtually all living processes.

X-ray Absorption Spectroscopy
BL9-3
July 2006
Figure 1.

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.

X-ray Absorption Spectroscopy
BL4-1, BL6-2
June 2006
Figure 1.

After years of wondering how organisms managed to create medically valuable natural products, like antibiotics and anti-fungal agents, chemists have discovered the surprisingly simple secret by shining x-ray light on the problem. MIT and Harvard researchers used crystallography beam lines at the Stanford Synchrotron Radiation Laboratory and the Advanced Light Source in Berkeley for their research.

Macromolecular Crystallography
BL9-2

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