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 and to add your most recent publications to this collection.

While we continue to refine our science highlights content you may access older science summaries that date between 04/2001 to 06/2010 by visiting http://www-ssrl.slac.stanford.edu/science/sciencehighlights.html. We will be offering science summaries that date from 06/2012 to the present soon.

July 2014
Daniel Friebel, SUNCAT, Ifan Stephens, Technical University of Denmark, Ib Chorkendorff, Technical University of Denmark
Figure

A team of researchers from the Technical University of Denmark and  the SUNCAT Institute at the SLAC National Accelerator Laboratory and Stanford University has demonstrated the superior performance of nanoparticles of platinum-yttrium (PtxY) as catalysts for oxygen electroreduction.

Polymer electrolyte membrane fuel cells (PEMFCs) hold the promise to potentially become zero-emission alternative power sources for automotive vehicles.  Moreover, in comparison to batteries, they provide much longer driving ranges and faster refueling times.  Even so, the widespread use of PEMFCs has been hampered by the need for a large amount of platinum catalyst at the cathode, where oxygen reduction takes place.  Even with current state-of-the-art technology, it is too expensive to scale up PEMFC production to make a global impact.

X-ray Absorption Spectroscopy
BL11-2
July 2014
Andrea Edwards, Stanford University, Thomas Weiss, Stanford Synchrotron Radiation Lightsource

Many organisms produce chemicals known as secondary metabolites that are not directly vital for survival but often play important roles in the organisms’ defense against other species. Due to their wide range of medically relevant properties, these compounds are also of great interest to humankind. The secondary metabolite erythromycin, for instance, is an important antibiotic of bacterial origin. Recently, researchers have shed light on the structural architecture of 6-deoxyerythronolide B synthase (DEBS) – a large multi-protein complex that acts as an assembly line for one of erythromycin’s precursors.

Biological Small-angle X-ray Scattering (BioSAXS)
BL4-2
June 2014
Hirohito Ogasawara, SSRL, May Ling Ng, SUNCAT, Sarp Kaya, JCAP (currently Koç University (Turkey))

Photosynthesis, i.e. the conversion of sun light into stored chemical energy by plants and other organisms, is one of the most important global biological processes. In light of increasing energy prices, limited fossil fuel resources and rising environmental concerns, researchers have long dreamed of reproducing this natural process in order to address the challenge of sustainable and eco-friendly energy production. A particularly difficult photosynthetic step to replicate is the oxidation of water and concomitant production of oxygen, which, in artificial systems, require the use of catalysts that are both reactive and stable. In a recent study researchers probed changes in an iridium oxide catalyst during water oxidation, providing crucial insights into the catalytic performance of this material.

BL13-2
June 2014
Christopher Kim, Chapman University, Samuel Webb, SSRL

The toxic element arsenic occurs naturally in the Earth’s crust and is enriched in precious metal deposits. Due to mining activities, its concentration in the air, water and soil may dramatically increase and pose significant health risks. Therefore, a proper risk assessment is required as part of planned residential developments near former mining sites. However, not all arsenic species are equally toxic and researchers must consequently not only determine how arsenic is distributed in the region but also in which chemical forms it is present.

BL2-3, BL11-2
May 2014
Michael E. Birnbaum, Stanford University, K. Christopher Garcia, Stanford University
T Cell Figure

As a crucial part of an organism’s immune system, T cells detect and fight infection and cellular dysfunction. Each T cell has a unique T-cell receptor (TCR) on its surface that recognizes and binds peptide antigens, triggering an immune response. The peptide antigens themselves, often stemming from intruding organisms such as bacteria, are bound to molecules known as major histocompatibility complexes, or MHCs. TCRs show a great deal of diversity in order to ensure that the large number of potential antigens can be detected. Although of great medical interest, predicting what peptides a given TCR recognizes has been challenging. A team led by researchers has now found a way to increase the success of such predictions from 30 to up to 90 percent.

Macromolecular Crystallography
BL11-1, BL12-2
May 2014
Aaron Lindenberg, Stanford University/SLAC, Michael Kozina, Stanford University/SLAC, Apurva Mehta, SSRL
Figure 1

Optical pump/x-ray probe experiments are key for studies of ultrafast processes in a wide range of materials. In these experiments, an optical pump laser pulse excites a sample and is followed by an x-ray probe pulse that determines the sample’s response. Such studies have been primarily focused on non-equilibrium situations, in which the pump pulse causes strong perturbations, and typically probe pulses with rather low repetition rates. A team of researchers has recently put a complementary approach to the test, exploring weak perturbations and high repetition rates.

BL10-2
May 2014
Sunita P. Ho, University of California San Francis,, Joy C. Andrews, SSRL, Piero Pianetta, SSRL
Figure

Local changes of the periodontal ligament (PDL), i.e. the connective tissue fibers attaching teeth to the jaw bone, can cause abnormal dental conditions such as ankylosis, which affects growth and development of the jaw and potentially leads to jaw distortions. In a recent study researchers conducted an in-depth study of bony protrusions within the PDL space – changes that occur due to age and other factors.

BL2-3, BL6-2
May 2014
Courtney M. Roach (Krest), SSRL, Michael T. Green, Pennsylvania State University
Figure 1

Cytochrome P450s make up a large family of iron-containing enzymes that catalyze the oxidation of organic substances. As nature’s detoxifiers, they are responsible for 75 percent of the phase one metabolism of pharmaceuticals. A long-standing mystery of P450s is how they can perform these rather aggressive reactions without damaging their own protein structures in auto-oxidation reactions. With a recent study  researchers have made a large step forward in understanding this enigmatic chemistry, opening up new possibilities for biological, medical and synthetic P450 research.

BL7-3
April 2014
Feng Lin, Lawrence Berkeley National Laboratory , Marca Doeff, Lawrence Berkeley National Laboratory, Dennis Nordlund, Stanford Synchrotron Radiation Lightsource, Tsu-Chien Weng, Stanford Synchrotron Radiation Lightsource
NiO overview figure

Rechargeable lithium-ion batteries are widely used in applications ranging from consumer electronics to electric vehicles. An important feature of a high-quality battery is a long lifetime, i.e. a large number of possible charge-discharge cycles. However, every cycle introduces changes in the battery’s electrode material, limiting its cyclability. A research collaboration has recently examined the occurring structural and chemical changes in the electrode material during cycling and linked them to the performance of lithium-ion batteries.

 

X-ray Absorption Spectroscopy
BL10-1
April 2014
Donghui Lu, Stanford Synchrotron Radiation Lightsource
HTSC Figure 1

High-temperature superconductors are materials whose electrical resistance vanishes below critical temperatures that are much higher than for conventional superconductors. As potential energy-saving electrical conductor materials, they are of immense interest for a wide range of industrial applications. Despite extensive research, the exact mechanism behind high-temperature superconductivity has remained an unsolved mystery. Now, an international team of researchers has solved an important piece of the puzzle.  Read more...

Angle-resolved photoelectron spectroscopy
BL5-4

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