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.

March 2014

Fatty acids are key components of a variety of biological functions ranging from cellular membranes to energy storage. In addition, they are of great interest as potential “green” biofuels and targets in the development of novel antibiotics. In order to fully exploit their potential, researchers must first understand in detail how organisms synthesize fatty acids. However, due to the dynamic nature of the process, structural and functional studies of fatty acid biosynthesis are very challenging. A team of scientists has recently made a giant leap forward by determining the structure of a protein–protein complex that represents a snapshot of fatty acid biosynthesis in action.

Macromolecular Crystallography
BL12-2
March 2014

Proteins are molecules with a wide range of functions in all living organisms. As potential drug targets, they are of great interest for pharmaceutical and medical research. Proteins are built from long amino acid chains that fold up into three-dimensional structures, which determine the proteins’ functions. In most cases, proteins fold into only one specific, albeit, dynamic structure. Now, scientists have determined that the protein VP40 of the Ebola virus assumes three completely different structures with three very different biological functions.

Macromolecular Crystallography
BL11-1, BL12-2
February 2014
Yijin Liu, SSRL, Wenge Yang, Carnegie Institution of Washington / Center of High Pressure Science and Technology Advanced Research (China)
Illustration

It is common knowledge that materials expand when heated. However, a chemical compound known as BiNiO3 proves to be quite extraordinary in that it contracts with rising temperature. By mixing BiNiO3 with “conventionally” expanding materials, it becomes possible to produce composite materials with zero or other desired thermal expansion values – a possibility with great potential for engineering and other applications. The same transition from a low-density to a high-density phase of BiNiO3 observed for increasing temperatures can also be induced by applying high pressure.

BL6-2, BL6-2c
February 2014
Samaresh Guchhait, University of Texas at Austin, Hendrik Ohldag, SSRL
Figure 1

Carbon-based materials are extremely lightweight and have thermal, mechanical and electrical properties that are of great interest for use in functional devices. Carbon materials can be manufactured in virtually any shape and even with dimensions on the micro- and nanoscales. Recent research is now aimed at exploiting the spin and magnetism of carbon-based materials for data storage devices – a field called spintronics.

X-ray diffraction
BL11-3, BL13-1
February 2014
Sarp Kaya, SUNCAT, Frank Abild-Pedersen, SUNCAT
Figure 1

Graphite and diamond are two distinct forms of the same element, carbon. Nevertheless, their properties could not be any more different. For instance, diamond is extremely hard and can be used in cutting tools. Graphite, on the other hand, is soft and used in pencils. Graphite can be converted into diamond in a process that usually requires very high pressure. However, scientists have recently suggested an alternative route to obtain diamond-like structures from graphite – at least on the nanoscale.

X-ray Absorption Spectroscopy, Photoemission spectroscopy
BL13-2
January 2014
Yulin Chen, Stanford University, Oxford University, Zhi-Xun Shen, Stanford University
figure

Topological insulators comprise a new state of quantum matter that has been predicted theoretically and realized experimentally in the past few years. Strong inversion asymmetry in topological insulators could lead to many interesting phenomena, such as pyroelectricity, intrinsic topological p-n junctions and topological magneto-electric effects.

Researchers using Beam Line 5-4 at SSRL and Beam Line 10.0.1 at the ALS have shown the compound BiTeCl to be the first topological insulator with a strong inversion asymmetric crystal structure.

Angle-resolved photoelectron spectroscopy
BL5-4
December 2013
Hirohito Ogaswara, SSRL
Fuel Cell Figure 1

Polymer-electrolyte-membrane (PEM) fuel cells are potential candidates for the environmentally friendly and cost-efficient production of renewable energy from hydrogen and oxygen. At the fuel cell’s anode, hydrogen gas is split into protons, which subsequently combine with oxygen gas at the cathode to produce water. However, current PEM fuel cells are limited in their efficiency by the occurrence of several competing oxygenated intermediates at the cathode. A research team has now shed light on the interplay between different oxygenated species and fuel-cell performance.

BL13-2
November 2013
Wendy Mao, Stanford University
Figure 1

Earth’s inner structure is organized into layers. The outermost crust overlays the mantle, which, in turn, surrounds our planet’s core. The crust and mantle are mainly composed of silicate rocks. In contrast, Earth’s core is metallic, containing predominantly iron. But how did iron separate from the silicates in order to form the metallic core during Earth’s evolution? Researchers have recently provided evidence that the percolation of liquid iron alloys through a solid silicate matrix can explain the formation of Earth’s core.

BL6-2
November 2013
Frank Bridges, University of California Santa Cruz
PbTe figure

Lead telluride, PbTe, is a well-known material used for its thermoelectric characteristics. In 2010, a research study suggested a new property: At temperatures above 100 K, the Pb atoms may become displaced from their usual locations in the crystal lattice (0.2 Å at 300 K), inducing Pb-Te electric dipoles in the material. The proposal came as a surprise because temperature-induced electric dipoles, which may cause ferroelectricity in materials, are known to only form at low temperatures but not upon heating. Researchers have now set the record straight. In a recent x-ray study they found no evidence of high-temperature-induced dipoles, challenging earlier suggestions.

BL4-1
October 2013
Delia Milliron, LBNL
Nanocrystal in glass composites

Amorphous materials such as glasses have optical, electrochemical and transport characteristics that are closely linked to their inner structures. Modifying the structure of an amorphous material can create new properties that may be of interest for industrial applications. Recently, researchers have altered niobium oxide glass by inserting tin-doped indium oxide nanocrystals into its structure.

X-ray diffraction
BL11-3

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