SSRL Science Highlights Archive

Approximately 1,600 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.

August 2013
Jennifer Wilcox, Stanford University

The primary anthropogenic source of mercury (Hg) emissions into the atmosphere is coal-fired power utilities. This work explores materials designed for Hg capture to be applied in the ductwork of a power plant to prevent Hg release into the atmosphere. Bench-scale combustion experiments have been carried out, in which sorbent materials were placed in a simulated flue gas stream doped with ppb levels of Hg. The sorbent surfaces were probed using x-ray absorption spectroscopy to determine the mechanism of Hg binding and to ultimately improve solvent design. The spectroscopy data was analyzed alongside results from density functional theory (DFT) for benchmarking so that DFT can be used as a screening tool for material improvement and new design.

BL7-3
August 2013
Yuqiang Bi, University of Michigan, Kim Hayes, University of Michigan

Uranium (U) is one of the most prevalent radionuclide contaminants in soils and groundwater across the world as a result of nuclear fuel production, weapons manufacturing, and research activities. The environmental risks posed by U are determined largely by the degree of its mobility, which strongly depends on redox conditions.  Under oxic conditions, U(VI) is soluble and forms stable complexes with carbonate and calcium in groundwater. In contrast, reduced U(IV) species are often immobilized as sparingly soluble U(IV) solid phases such as uraninite (UO2) by biotic or abiotic redox processes.

X-ray Absorption Spectroscopy
BL4-3, BL11-2
July 2013
Nicole T. Schirle, The Scripps Research Institute, Ian J. MacRae, The Scripps Research Institute

Argonaute proteins play an important role in the biological process of RNA interference (RNAi).  Scientists have now determined the crystal structure of human Argonaute2, thereby making progress toward a detailed understanding of Ago2 interactions with target RNA which may benefit the design of novel RNAi therapeutics. 

Macromolecular Crystallography
BL11-1
July 2013
Jena E. Johnson, California Institute of Technology (jena@caltech.edu)

For most modern-day terrestrial life, oxygen has become indispensable. At the heart of oxygenic photosynthesis is the production of oxygen from water – a process mediated by the water-splitting manganese cluster of Photosystem II. Little is known about how oxygenic photosynthesis originally evolved, although some have hypothesized a manganese-oxidizing photosystem as a precursor step.

BL2-3, BL4-1, BL10-2
July 2013
Debanu Das, JCSG, SSRL Structural Genomics
UCE figure

UCE plays a key role in the functioning of lysosomes, cellular sacs full of digestive enzymes that break down bacteria, viruses and worn-out cell parts for recycling. When this recycling process goes awry, it can cause rare metabolic diseases such as Tay-Sachs and Gaucher, which often cause death in affected children by their early teens. Three years ago, researchers discovered that three mutations in UCE itself were linked to persistent stuttering that is passed down in families.

Macromolecular Crystallography
BL9-2
July 2013
Xiang-Lei Yang, The Scripps Research Institute (La Jolla, California)
SerRs Image

During evolution, organisms added new domains to tRNA synthetases, which are believed to enable additional functions beyond protein synthesis. For the very first time researchers have established an essential role for an appended domain of tRNA synthetase in organisms.

Macromolecular Crystallography
BL7-1
June 2013
Tina Izard, The Scripps Research Institute Florida
a-catenin figure

Cells bind each other using specialized cell surface adhesion complexes called adherens junctions. These complexes direct the formation of tight, Velcro-like contacts that are essential for the development, architecture, maintenance, and function of tissues in all higher organisms. Exactly how this cell to cell binding is accomplished has not been fully understood.  Researchers from the Florida campus of The Scripps Research Institute (TSRI) have now solved a piece of this puzzle by determining the structure of α-catenin using SSRL’s Beam Line 11-1.

Macromolecular Crystallography
BL11-1
June 2013
Lisa E. Mayhew, University of Colorado - Boulder, Alexis Templeton, University of Colorado - Boulder
water-rock image

Hydrogen gas is produced in chemical reactions between anoxic water and iron-rich rocks at temperatures above 200°C – conditions too hot to support life. However, at hydrothermal vents or hot springs, where hydrogen-rich fluids mix with cooler waters and temperatures have dropped sufficiently, hydrogen-consuming organisms can survive. Less is known about the amount and mechanism of hydrogen production from water-rock reactions occurring at temperatures within the temperature limits of life (≤122°C) and the potential for these reactions to support in situ microbial life. Given the large expanse of the Earth’s crust that likely interacts with water under these cooler conditions, it is possible that these low-temperature reactions could sustain extensive subsurface microbial communities away from Earth’s hot spots.

Researchers have used SSRL’s BL2-3 microXAS imaging instrument to study what happens in detail as hydrogen is produced at low temperatures when powdered rocks and minerals are submerged in anoxic water at 55°C and 100°C for a period of 100 days.  They found that spinels are key in hydrogen production, acting as mediators in the electron transfer between Fe2+ and water and thus play an important role in hydrogen production during low-temperature reactions.

BL2-3
May 2013
Jordi Cabana, Lawrence Berkeley National Laboratory
Chemical phase map and stem image

Li-ion batteries are key devices in the effort to develop efficient chemical energy storage from sustainable energy sources. However, any effort to optimize battery performance requires a deeper understanding of the fundamental mechanisms of diffusion and phase transformation in battery electrodes.

BL6-2
May 2013
Edward Snell, SUNY Buffalo / Hauptman-Woodward Medical Research Institute
Full-length Gln4 shown bound to tRNAgln

Aminoacyl-tRNA synthetases are required in all three domains of life to add the correct amino acid to its cognate tRNA, an essential step in protein synthesis. Despite their importance, no structure had been reported for any full-length eukaryotic, glutaminyl-tRNA synthetase (GlnRS), although structural data for two prokaryotic GlnRS species exists.

Macromolecular Crystallography, Biological Small-angle X-ray Scattering (BioSAXS)
BL4-2, BL11-1

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