Previous Editions____________________________________________________________________________SSRL Headlines Vol. 11, No. 5 November, 2010____________________________________________________________________________
Contents of this Issue:
1. Science Highlight —
Iron a Limited Barrier to Arsenic Contamination in Rice
The team, which included Stanford post doctoral researcher Angelia Seyfferth,
SSRL staff scientists Samuel Webb and Joy Andrews, and Stanford Professor Scott
Fendorf, used SSRL Beam Lines 10-2 and 6-2 to view the distribution of iron and
arsenic on rice roots, revealing that the iron coating varies across roots,
affecting arsenic's entry into the plant. The researchers also found that many
young roots and younger portions of mature roots are not yet naturally coated
with iron and so allow arsenic to enter the root's cellular structure. This
suggests that overall, iron coatings may not be an effective barrier to arsenic
uptake by rice roots.
This work was published in the October issue of Environmental Science and
Technology.
To learn more about this research see the full scientific highlight
Using intense x-rays from SSRL's Beam Line 9-2 at the Department of Energy's
SLAC National Accelerator Laboratory, researchers have determined the detailed
structure of a key part of the ryanodine receptor, a protein associated with
calcium-related disease. Their results, which combine data from SSRL and the
Canadian Light Source, pinpoint the locations of more than 50 mutations that
cluster in disease "hotspots" along the receptor.
The ryanodine receptor controls the release of calcium ions from a storehouse
within skeletal-muscle and heart-muscle cells as needed to perform critical
functions. Previous studies at lower resolution indicated that mutations
cluster in three regions along the receptor, but without more detailed
information it remained unclear exactly how they contributed to disease.
In a study recently published in Nature, Van Petegem and his group
describe the structure of one of these hotspots in extremely fine detail and
predict how the mutations might cause the receptor to malfunction and release
calcium too soon. Read more at: http://home.slac.stanford.edu/pressreleases/2010/20101104.htm
To learn more about this research see the full scientific highlight
SSRL's 2010-2011 user run started the week of November 15. The run is scheduled
to last until July 25, 2011, with an estimated 1500 users coming to SLAC over
the course of the run to perform research using SSRL's x-ray beam lines.
The original plan was to begin the run at an operating current of 350 mA,
however, SPEAR3 vacuum problems resulting in frequent beam dumps have
necessitated scaling back to 300 mA. The accelerator physics period this week
has been used to troubleshoot the vacuum problems. Specifically, a new pump on
a RGA near the rf cavities has been installed and the RGA vacuum system is
being baked out. This will allow use of the RGA during the regularly scheduled
maintenance day on Monday December 6. In addition a vacuum leak check was
performed near the BL13 ID and a small leak found and hopefully repaired. The
vacuum pressure in this region will be monitored frequently over the next few
days to determine if the repair was successful and if additional repairs are
necessary. Additional AP time was used to minimize the possibility of the
vacuum leak causing SPEAR3 beam losses and making recovery even quicker. The
SPEAR3 current will remain at 300 mA while we evaluate the effectiveness of the
vacuum repair and other mitigations.
Work at the SPEAR3 storage ring during the annual downtime involved projects
both large and small to support the continued use of frequent-injection mode.
Frequent injection is necessary to support SPEAR3's goal of reaching its full
design current of 500 mA-and improved data collection for researchers using
SSRL's bright x-rays. But frequent injection has challenges of its own. Read
more at: http://today.slac.stanford.edu/feature/2010/ssrl-spear-upgrade.asp
A multi-year project to reorganize the computer network for the SPEAR3
accelerator and beam lines is bearing fruit, according to Clemens
Wermelskirchen, manager of the SPEAR3 control system and network, and his
counterpart for the SPEAR3 beam lines, Martin George. The goal is to improve
network performance and reliability-as vital to the performance of the
accelerator and beam lines as mechanical upgrades and maintenance,
Wermelskirchen said. "The SPEAR3 control system can never go down," he stated.
"If we lose a significant network component, we lose the accelerator." However,
the previous organization of the network coupled with the growth of SSRL made
the network increasingly difficult to support. Read more at: http://today.slac.stanford.edu/feature/2010/ssrl-networking.asp
We are gathering data to compile for our 2008-2010 upcoming February 2011
review by the U.S. Department of Energy's Office of Basic Energy Sciences.
Metrics of productivity and peer recognition resulting from work done at SSRL
are crucial components of the review. Please take a few minutes now to send us
your updated list of SSRL related publications, awards and invited talks. Thank
you in advance for your assistance with collecting this important information.
SSRL Publications: http://www-ssrl.slac.stanford.edu/publications/
The inaugural USA Science & Engineering Festival was held recently in
Washington and included participation from many DOE laboratories, including
LCLS Deputy Director Uwe Bergmann who gave a presentation on 'X-ray Vision:
Revealing Ancient Secrets with New Technology' in one of the AAAS Meet the
Scientists sessions. The National User Facility Organization (NUFO) also
conducted hands-on demonstrations at their exhibit booth to stimulate interest
and make science fun for the 5,000 students, parents and teachers who
participated in this festival. Read more about this most recent outreach and
education event and other NUFO news at http://www.nufo.org/news.aspx and
http://www.aps.anl.gov/Users/Communications/User_News/2010/user_news_65.html#03
X-ray/VUV Beam Time Requests for February through May 2011 beam time are due
Wednesday, December 1. Please submit your requests via our user portal:
December 1 is also the next deadline for submitting new X-ray, VUV and
Macromolecular Crystallography proposals. New proposals should be submitted
through our user portal as well.
Researchers are invited to submit scientific proposals for soft and hard x-rays
at the LCLS AMO, SXR, XPP, CXI, XCS, and MEC (with limited capability)
instruments. Proposals submitted by January 11 will be eligible for beam time
~October 2011-February 2012. Learn more about the latest developments by
contacting LCLS staff scientists and reviewing detailed instrument descriptions
available on the LCLS web site at: http://lcls.slac.stanford.edu/Instruments.aspx
New capabilities available to users for this call include a ~100 nm focus in
CXI and the first time availability of the XCS and MEC instruments. LCLS has
demonstrated FEL operations over the energy range 480 eV to 10 keV using the
fundamental with pulse energies of 1-3 mJ depending on the pulse duration.
Further, LCLS will deliver photons up to 20 keV from a second harmonic
afterburner with a flux reduced by roughly an order of magnitude. The pulse
length can be varied over 70-300 fs for hard x-rays, while for soft x-rays, the
range is extended to 70-500 fs. Shorter pulses (<10 fs) with reduced pulse
energy (number of photons per pulse) can also be provided by returning the
injector to run at lower charge. The maximum repetition rate of the LCLS is
expected to be 120 Hz during this run. http://lcls.slac.stanford.edu/Article.aspx?article_id=235
Submit proposals at: https://www-ssrl.slac.stanford.edu/URAWI/Login.html
(note: spokespersons must be registered and approved as users
to submit a proposal)
We have SSRL/LCLS long sleeve & short sleeve t-shirts for sale. Please stop
by User Research Administration, SSRL Bldg. 120, if you are interested. Sizes
available include M, L, XL, XXL & XXXL in the short sleeve and L, XL, XXL &
XXXL in the long sleeve version. These t-shirts make great gifts!
http://www-conf.slac.stanford.edu/ssrl-lcls/2010/pdfs/tshirt.pdf
__________________________________________________________________________
SSRL Headlines is published electronically monthly to inform SSRL users,
sponsors and other interested people about happenings at SSRL. SSRL is a
national synchrotron user facility operated by Stanford University for the
U.S. Department of Energy Office of Basic Energy
Sciences. Additional support for
the structural biology program is provided by
the DOE
Office of Biological and Environmental Research, the NIH
National Center for Research Resources and the NIH Institute for General Medical
Sciences. Additional information about
SSRL and its operation and schedules is available from the SSRL WWW
site.
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