Electronic Structure of Cobalt Nanocrystals Suspended in Liquid
Advances in the synthesis of crystals of nanometer dimensions, narrow size distribution, and controlled shape have generated interest because of the potential to create novel materials with tailored physical and chemical properties. New properties arise from quantum confinement effects and from the increasing fraction of surface atoms with unique bonding and geometrical configurations. At the ALS, an international team of scientists has performed an electronic structure study of colloidal nanocrystals—nanocrystals suspended in the liquid solvent in which they were grown. A range of photon-in/photon-out spectroscopies, including x-ray absorption spectroscopy (XAS), was applied. These techniques are element-selective, as they involve core atomic levels and can thus probe the local electronic structure of selected species in complex systems. Read more…
Publication about this research: H. Liu, J. Guo, Y. Yin, A. Augustsson, C. Dong, J. Nordgren, C. Chang, P. Alivisatos, G. Thornton, D.F. Ogletree, F.G. Requejo, F. de Groot, and M. Salmeron, “Electronic structure of cobalt nanocrystals suspended in liquid,” Nano Lett. 7, 1919 (2007).
The Iron Spin Transition in the Earth’s Lower Mantle
It is now known that the iron present in minerals of the lower mantle of the Earth undergoes a pressure-induced transition with pairing of the spins of its 3d electrons. A team from the University of California, Berkeley, Tel Aviv University, and Lawrence Livermore National Laboratory has used x-ray diffraction at very high pressure to investigate the effects of this transition on the elastic properties of magnesiowüstite (Mg1–xFex)O, the second most abundant mineral in the Earth’s lower mantle. The new results suggest that the effect of the spin-pairing transition on magnesiowüstite can be large enough to require a partial revision of the most accepted model of the lower mantle composition. Read more…
Structure of Synaptic Connectors Solved
Establishment of neural connections at specialized intercellular junctions called synapses is critical for proper brain function, and errors in the process are thought to be associated with autism and other disorders. Researchers from Stanford University and the University of Texas Southwestern Medical Center have reported high-resolution, three-dimensional structures of the proteins, called neuroligin-1 and neurexin-1β, that form this connection. Because mutations in the neurexin and neuroligin genes are among the multiple genetic causes of autism, understanding the molecular mechanism of these proteins in synapse development is a first step towards development of novel therapeutics directed to treat and possibly cure autism. Read more…
Publication about this research: D. Araç, A.A. Boucard, E. Özkan, P. Strop, E. Newell, T.C. Südhof, and A.T. Brunger, “Structures of Neuroligin-1 and the Neuroligin-1/Neurexin-1β complex reveal specific protein-protein and protein-Ca2+ interactions,” Neuron 56, 992 (2007).
Status of the User Support Building and Berkeley Lab Guest House Projects
User Support Building. The project team has been working to minimize the impacts of the directed funding change for the project this fiscal year (17M). We are moving forward with a phased-construction model and plan to break ground this summer to install the foundations and underground utilities. Work on this phase should be completed around the end of the calendar year. The next phase will begin in spring/summer 2009 and will include the structural steel and exterior skins of the building. This phase be will completed around the end of calendar year 2009. The final project phase will begin in spring/summer 2010 and include the entire interior of the building. Depending on how early the funding for the 2010 fiscal year arrives, the project will be completed in either late 2010 or early 2011. We have scheduled a six-week shutdown this fall, beginning on September 2nd, to accommodate construction work that is not compatible with ALS user operations due to vibrations. This plan coincides well with other shutdown needs at this time. We are thrilled that we are moving moving forward on this critical facility, which will improve our support for our users.
Berkeley Lab Guest House. Design work on the 57-room Guest House has been moving rapidly. Trees were removed earlier this month, allowing construction to begin this week. We anticipate construction of the relatively simple wood-framed structure to be completed in April 2009 and the Guest House to be open for guests shortly thereafter. We are also looking for an operator for the Guest House. The selection of an operator will allow us to determine room rates and better define services. We hope to receive a proposal in the coming few weeks that will conclude this effort.
UEC Corner: Users’ Meeting Update
The preparations for the 2008 ALS Users’ Meeting (beginning October 13) are well underway. Apart from talks highlighting the outstanding science that has been performed by ALS users over the past year, the meeting program will feature presentations by Berkeley Lab Director Steve Chu addressing the future of the laboratory and the role of the ALS. ALS management will report on the current status of the ALS, and representatives from the Office of Basic Energy Sciences, Department of Energy (DOE), will provide insight into the current funding situation and its future. We will also hold a special session in memory of Daniel Chemla, former director of the Advanced Light Source, who recently passed away. During this session, Patricia Dehmer (Office of Science, DOE) and Charles Shank (University of California, Berkeley) will share their memories of Daniel with us, and Paul Alivisatos (Berkeley Lab Deputy Director) will give a special scientific talk. We hope you can all attend this very special session to remember Daniel.
In addition, the meeting will feature a Town Hall meeting, a poster session held in collaboration with the Molecular Foundry, and presentations by the winners of the Halbach, Shirley, and poster awards. The program committee is currently assembling a list of workshops that will take place on October 14 and continue on through the morning of the 15. Anyone who is interested in holding a workshop should immediately contact Phil Heimann or Wayne Stolte.
New Pressure Record Set at the ALS
The highest pressure achieved on Beamline 12.2.2 , the extreme conditions beamline at the Advanced Light Source, was surpassed on Saturday, April 26, by Kirill Zhuravlev from the Geological and Planetary Science department of CalTech. He set the new record of 1.12 million bar using a symmetric diamond anvil cell while measuring the equation of state of an iron rich ferropericlase sample. This pressure is equivalent to that which exists at the boundary of the Earth’s mantle and core. This work is aimed at helping us to understand the structure of the inner most Earth and will feed into improving our current models of planetary evolution.
Memorial Service for Daniel Chemla. A memorial for Daniel Chemla will be held on Saturday, May 10, from 10 a.m. to 12 noon at UCB Pimentel Hall (directions and map) followed by a reception from 12 noon to 2 p.m. at the Men’s Faculty Club (directions and map).
ALS Video Tour Makes It to YouTube. Among the highlights of a UC Berkeley class offered last spring, “Synchrotron Radiation for Materials Science Applications,” was a tour of the ALS, which was videotaped and recently posted on YouTube. The class took students to the light source for a crash course on the early development of cyclotrons, the inner workings of the ALS, recent equipment updates, and its service as a national user facility. The tour overview was provided by ALS scientist Tony Warwick.
Updated Operating Schedule. The long-term operating schedule has been revised in order to increase the 2-bunch time in the next cycle (July–December 2008). In addition, the number of multibunch (MB) shifts has been revised to 275. Click here to view the latest schedule.
For the user runs from March 18 to April 20: Beam reliability*: 91.9%; Completion**: 87.8%.
This period included the second week of 2-bunch user operations. Failure of a cable in the storage-ring series QFA power supply on March 25 resulted in the loss of over 9 hours of scheduled beam time.
Questions about beam reliability should be sent to David Richardson.
Requests for special operations use of the “scrubbing” shift should be sent to Rick Bloemhard (ALS-CR@lbl.gov, x4738) by 1:00 p.m. Friday.
*Time delivered/time scheduled