Stanford Synchrotron Radiation Lightsource

In solids, Fermi surfaces are the boundaries between occupied and unoccupied electron levels, as defined in momentum space. Their properties dictate that each Fermi surface should form a single unbroken loop. To the surprise of physicists, disconnected segments of the Fermi surface – Fermi arcs – were discovered in cuprate superconductors in 1998.

In a study recently published in Nature Physics, researchers from the University of Colorado have used angle-resolved photoemission spectroscopy (ARPES) at SSRL Beam Line 5-4 to determine the origin of these Fermi arcs in the cuprates.

Olefins are the basic building blocks for many products from the petrochemical industry and are currently produced by steam cracking of naphtha or ethane, but increasing oil and gas prices are driving the industry toward producing olefins from syngas derived from cheaper feedstocks via the Fischer-Tropsch process instead. A team of scientists used full-field Transmission hard X-ray Microscopy (TXM) and a special reactor designed and built at SSRL and installed on SSRL Beam Line 6-2 to learn more about the catalyst at the heart of the Fischer-Tropsch-to-Olefins (FTO) process.

The structural, electronic, and magnetic properties of U and Pu elements and intermetallics remain poorly understood despite decades of effort, and currently represent an important scientific frontier toward understanding matter. The last decade has seen great progress both due to the discovery of superconductivity in PuCoGa₅ and advances in theory that finally can explain fundamental ground state properties in elemental plutonium, such as the phonon dispersion curve, the non-magnetic ground state, and the volume difference between different phases of the pure element.

Flavin-dependant thymidylate synthases (FDTSs) are a class of recently identified family of thymidylate synthases that employ novel mechanism for the thymidylate synthase reaction. Thymidylate synthases use N⁵,N¹⁰-methylene-5,6,7,8-tetrahydrofolate (CH₂H₄folate) to reductively methylate 2’-deoxyuridine-5’-monophosphate (dUMP) producing 2’-deoxythymine-5’-monophosphate (dTMP). dTMP is one of the four DNA building blocks and is crucial for survival of all organisms. Unlike other deoxynucleotides, dTMP cannot be directly synthesized by a ribonucleotide reductase, and its de novo biosynthesis requires the enzyme thymidylate synthase. Therefore, inhibition of thymidylate synthesis stops DNA production, arresting cell cycle and eventually leading to “thymineless” cell death. The human enzyme has long been recognized as a target for anticancer drugs.

Since FDTS enzymes are mainly found in very pathogenic microbes including the pathogens causing leprosy, botulism, diarrhea, anthrax, pneumonia, syphilis, etc., the FDTS enzyme is an attractive target for antibiotic drugs.