Vol. 12, No. 12 - June 2012
|From Director Chi-Chang Kao|
The SSRL Scientific Advisory Committee met on June 8 and 9. The meeting covered several important issues. First, the demand for beam time at SSRL continues to grow, and we are working with the SAC to evaluate the proposal review process to see if we could improve the current system with the aim to optimize scientific impact. Second, SAC reviewed and approved the first batch of Collaborative Access Proposals. We will use the terms and conditions developed for these CAP proposals as a general guideline for the development of future partnership between SSRL and user community. Third, we presented to SAC new scientific opportunities in molecular environmental & interface science, and high magnetic fields.
On June 26, SSRL staff, working in collaboration with representatives of the
SLAC Radiation Protection Division, successfully completed high current
radiological characterization of the last two SSRL beam lines in preparation
for operating with up to 500 mA stored current in SPEAR3. These carefully
planned studies, which have been conducted over the course of seven Accelerator
Physics shifts during the FY2012 user run, represented the last major
qualification effort necessary before the anticipated release to operate SSRL
beam lines at the full SPEAR3 design current of 500 mA. In parallel with these
radiological studies, SSRL staff have characterized beam line performance at
elevated current with particular attention paid to the high power insertion
device beam lines.
To honor Herman Winick's 80th birthday (which happened on June 27), Herman's colleagues both within and outside of SLAC are planning a one-day symposium on October 2, 2012 on the day before the LCLS/SSRL Users' Meeting. Herman, who is Deputy Director Emeritus of SSRL, has been a strong proponent of synchrotron radiation since he came to Stanford in the 1970's to lead the technical design of SSRP (the Stanford Synchrotron Radiation Project) at the time. He is best known for his leadership role, starting in the mid-1970's, in the development of wiggler and undulator insertion devices as advanced synchrotron radiation sources. He pushed to operate PEP at reduced energy in the late 1980's as the lowest emittance light source to date, and participated in the study with Claudio Pellegrini (UCLA) and others to implement a soft X-ray FEL in a switched bypass in PEP, a concept that is now being considered for PEP-X. In 1992, he and Pellegrini initiated studies of the Linac Coherent Light Source (LCLS) Project to construct an x-ray laser using the SLAC linac which became the LCLS. He has also been active internationally to promote the development of facilities in many countries, the latest being his efforts in the initiation of SESAME (www.sesame.org.jo), a UNESCO-sponsored project which is now constructing a synchrotron radiation laboratory in Jordan, with nine countries in the Middle East participating.
We anticipate an exciting symposium to celebrate Herman's significant accomplishments and more information will become available on the LCLS/SSRL Users' Meeting website as the program develops.
SSRL Data Directs Prostate Cancer Drug Design
Prostate cancer, the most common cancer in men, is often a localized, slow-growing cancer, which aids treatment and improves survival rates. However, highly aggressive, metastatic forms of the cancer occur frequently enough to make it the No. 2 cause of death in U.S. men, and there is a lack of effective drugs to fight these more aggressive cancers. Since prostate cancer cells proliferate in the presence of androgen steroid hormones such as dihydrotestosterone, blocking the synthesis of such hormones is an obvious strategy for treating prostate cancer. A promising target is cytochrome P450 17A1 (CYP17A1), a heme-containing monooxygenase that produces androgens via a two-step process. However developing drugs targeted to CYP17A1 has proven challenging because of a lack of information about the enzyme's structure. CYP17A1 is partially embedded in membranes and the technical difficulties of generating, stabilizing, and forming crystals of this protein had long frustrated attempts to determine the enzyme's structure.
Dr. Emily Scott and Natasha DeVore from the University of Kansas overcame this challenge, and used SSRL macromolecular crystallography BL9-2 to solve the structure of CYP17A1 in the presence of two promising drugs, abiraterone, which was recently approved by the FDA, and TOK-001, which is in early clinical trials. The structural information revealed how the drugs bind, which is different from what had been predicted by other methods, and immediately provides insights on how to improve these drugs or design new drugs. Read more...
Learn more at this University of Kansas news release
X-ray Characterization of Lithium-Sulfur
Batteries in Action
Dramatic improvements in energy storage devices are essential to meet the increasing need to move away from fossil fuels and toward clean, renewable energy. Rechargeable lithium-sulfur (Li-S) batteries hold great potential for high-performance energy storage systems because they have a high theoretical specific energy, low cost, and are eco-friendly; but a better understanding of how the battery functions is required to design improvements for higher efficiency and capacity.
Scientists from SSRL and Stanford University have used a two-pronged approach to characterize Li-S batteries during normal battery operation, a process dubbed in operando. In operando x-ray diffraction (XRD) at SSRL tracked real-time changes in the active battery material's crystal structure, while in operando x-ray imaging revealed nanometer-sized changes in the material's morphology, showing that during the battery discharge cycle crystalline sulfur interacted with lithium to form amorphous polysulfides. However, that process was not followed by the complete loss of the polysulfides into the electrolyte and the formation of crystalline Li2S, as reported in ex situ XRD studies, confirming that ex situ studies can lead to false conclusions about battery mechanisms. These results will guide future electrode designs in order to increase capacity in subsequent cycles and prolong battery life, such as encapsulating the sulfur to increase the Li-S lifetime. Read more...
Catalyst Design Parameters Revealed
Changing the electronic structure of a catalytic metal in order to "tune" its performance is a key element in the design of new, more efficient catalysts. Tailor-made catalysts are particularly needed in fuel cells, which could efficiently power electric vehicles without the range limitations of current batteries. However, two requirements of such a catalyst require an extremely careful design to provide high catalytic activity (to minimize the need for costly materials) and high stability (to prevent degradation during long-term operation in a corrosive environment). Recently, SIMES and SUNCAT researchers joined efforts at SSRL to examine the "tuning" of a bimetallic fuel cell catalyst consisting of ultrathin platinum layers grown on a single-crystal rhodium substrate. They discovered that both activity and stability of the platinum-rhodium catalyst could be optimized if, in addition to its elemental composition, its nanostructure is made a design criterion.
The SIMES team, led by Associate Staff Scientist Daniel Friebel, used grazing incidence x-ray absorption fine structure techniques at SSRL Beam Line 11-2, and found two very different nanostructures: one in which the platinum was deposited in the rhodium substrate in a single, atom-thick layer, and one in which the same amount of platinum formed thicker islands with voids in between. The team then used high-energy resolution x-ray absorption spectroscopy at Beam Line 6-2 to examine the electronic structure of both nanostructures in an electrolyte solution. The studies showed a markedly different behavior: the platinum islands exhibited a much greater affinity to adsorbed oxygen species than the single platinum monolayer, with adsorbed oxygen almost completely absent on the latter. Density functional theory established a simple correlation between oxygen chemisorption energy and the local metallic coordination environment. Researchers were also able to predict which platinum sites would be most active, and that an optimized platinum-rhodium nanostructure could be up to five times more active than pure platinum. Moreover, such a structure is expected to be much more stable against catalyst degradation than platinum-nickel or platinum-cobalt catalysts with comparable activity, thus fulfilling both requirements of high activity and stability. Read more...
Users and administrators met in Santa Fe June 18-20 for the annual meeting of the National User Facilities Organization (NUFO). The meeting included discussions related to strengthening relationships with scientists from academia and industry as well as leveraging resources to better communicate the importance of scientific work conducted at national user facilities. The results of the recent NUFO Steering Committee elections were also announced, acknowledging retiring members Cathy Knotts (SLAC), Al Ekkebus (ORNL), Mike Crawford (DuPont), and welcoming new members Susan Bailey (LBNL), Yves Idzerda (Montana State University, ALS UEC), Steve Wasserman (Eli Lilly), Beth Wurzburg (SSRL UEC) and welcoming Katherine Kantardjieff (CSU San Marcos, SSRL UEC) who rotates from the Vice-Chair to the NUFO Chair position.
On June 21, NUFO Chair Tony Lanzirotti spoke before the subcommittee of the House Committee on Science, Space and Technology, for a session devoted to Department of Energy (DOE) user facilities. Other speakers included SLAC Director Persis Drell (https://news.slac.stanford.edu/features/director-testimony-house), Suzy Tichenor from Oak Ridge National Laboratory, Steve Wasserman from Eli Lilly, and Ernest Hall from GE Global Research. A press release and webcast of the session can be viewed on the committee's Web site.
Please see the NUFO website, NUFO on Facebook (National User Facility Organization), Twitter (@NUFO_users), Linkedin (NUFO), and YouTube (NatlUserFacOrg) or subscribe to our RSS feed at nufonuggets.blogspot.com.
Dr. Sharlene Weatherwax, the Associate Director of Science for Biological and Environmental Research (BER) within the Department of Energy's Office of Science, visited SLAC on Thursday, June 21. The visit included a SLAC science program overview by Acting SLAC Director Norbert Holtkamp, a tour of SSRL's Structural Molecular Biology and Molecular Environmental Science beam lines including interactions with SSRL staff scientists, and a visit to the LCLS CXI station and description of ongoing nanocrystallography activities.
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