Stanford Synchrotron Radiation Lightsource

An international collaboration that included researchers at SSRL has used x-ray scanning microprobe fluorescence techniques at BL6-2 to characterize the elemental chemistry of samples from comet 81P/Wild-2 brought back aboard the Stardust spacecraft last January. Twenty-three aerogel samples containing cometary particles were analyzed by the 175-member Preliminary Examination Team, and five of those samples were studied at SSRL. This collaboration provided the first look at the Stardust samples after the return, and results are presented in several publications in the December 15 issue of Science.

Research performed at SSRL has provided insight into why lead is so damaging to the healthy development of young children. Scientists from the University of Michigan and Northwestern University used x-ray absorption spectroscopy at SSRL to understand how lead can interfere with proteins that help transform DNA blueprints into working proteins that run the body.

Henry VIII's warship, the Mary Rose, wreaked havoc on the French navy for 34 years until she was wrecked in 1545. Salvaged from the sea in 1982, she now rests in the Mary Rose Museum in Portsmouth, England. Pieces of her helm recently traveled to SSRL and the ESRF in Grenoble, France, where intense x-rays pierced the wood to analyze the sulfur and iron within. Led by University of Stockholm Professor Magnus Sandström, researchers had studied another historical treasure, the Swedish warship Vasa, at SSRL in a similar way in 2001.

X-rays intended to elucidate the structure of biomolecules may actually damage and alter key parts of the molecules. A research team led by a group from Lawrence Berkeley National Laboratory (in collaboration with researchers from Max-Planck-Institut Mülheim, ESRF, SSRL, and TU Berlin and Freie Universität, Berlin) discovered this while investigating the Mn₄Ca complex, a site crucial for splitting water into oxygen during photosynthesis.

Iron metals oxidize to rust, losing electrons and gaining positive charge. Iron metals typically exist in an oxidation state of +2 or +3 (2 or 3 electrons less than a neutral iron atom). However, chemists have long thought that iron compounds with even higher oxidation states play important roles in enabling chemical reactions in metal-containing proteins.

Cadmium is known to be extremely toxic to mammals, and is generally viewed alongside mercury as an environmental problem and toxic element that is not used by nature in any way. A Brief Communication in the May 5 issue of the journal Nature shows that we need to revise our opinion of cadmium. The paper reports the purification and characterization of a previously unknown metalloenzyme from the marine diatom Thalassiosira weissflogii that specifically uses cadmium to achieve its biological function. This is the first cadmium enzyme that has been discovered.

Changing the electronic structure of a metal in order to “tune” its affinity to catalytic reaction intermediates is a key element in catalyst design. Tailor-made catalysts with a carefully adjusted ratio of two or more different alloy components are particularly needed in fuel cells, which could efficiently power electric vehicles – without the range limitations of current batteries.

The Hanford nuclear waste site in southeastern Washington State is one of the most contaminated sites in the DOE complex. It stores millions of gallons of radioactive waste from the nation's nuclear weapons programs. High-level radioactive waste is leaking from about a third of Hanford's underground tanks.

Chloroperoxidase is one of a large class of heme proteins that play important roles in a number of physiological processes, including xenobiotic metabolism, neurological development, blood pressure control, and immune defense. These heme protein systems all have the ability to oxygenate saturated hydrocarbons under ambient conditions, a process which is chemically quite challenging, and hence is also of industrial importance.

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.