Previous Editions__________________________________________________________________________SSRL Headlines Vol. 11, No. 8 February, 2011__________________________________________________________________________
Contents of this Issue:
The DOE review went very well based on what we heard from the reviewers both
during the review and at the closeout, although the final report will not be
available for another two to three months. The reviewers were uniform in their
very positive comments on the scientific productivity, legendary user support
and technical developments of SSRL, as well as the major steps taken by SLAC
over the last three years. In fact, one reviewer stated that, among DOE
laboratories that he is aware of, SLAC is the best in making science the
highest priority. This is a clear validation of the success of SSRL as a major
user facility.
I would like to take this opportunity to acknowledge the effort and teamwork of
the SSRL staff, as well as the assistance we received from many in the
laboratory, over the last few months. It's been a whirlwind, but a very
productive and useful one.
As we continue forward, I again ask for you to share your viewpoint and
suggestions for the SSRL strategic plan. Where should we be heading in the
coming decade? And what scientific areas are most important for us to consider
in our plans? I look forward to hearing from you.
—Chi-Chang Kao
Solar power is an important component of our society's future energy portfolio,
and organic materials may be the technology that makes solar cells cheap enough
for wide-spread implementation.
Currently, organic or plastic solar cells are relatively inexpensive to make,
yet they are also relatively inefficient. Researchers from Princeton University
and SSRL recently studied the structure of solar cells that were manufactured
and processed in different ways to better understand the causes of the
inefficiencies.
The experiments, conducted at SSRL Beam Line 11-3, showed a complex
relationship between the crystallinity of an organic solar cell's active layer
and the cell's output current. Output currents were not directly tied with the
crystallinity of the polymer (P3HT) in the active layer, as was expected.
Instead, the researchers found that the output currents were correlated with
the polymer crystallinity only in solar cells in which the fullerene derivative
(PCBM), also contained in the active layer, was locally well organized. These
results show that the structure of both components is very important, and
should both be considered to increase organic solar cell performance. This work
was published in the January 7, 2011 issue of Chemical Communications.
To learn more about this research see the full scientific highlight
Messenger RNA, responsible for relaying information from the DNA to the
ribosomes, is given a 5' cap and a 3' tail. The 3'-end cleavage and
polyadenylation are performed by a large protein complex that includes a
scaffolding protein called symplekin.
A research team led by Liang Tong of Columbia University used SSRL Beam Line
9-2 to solve the crystal structure of the N-terminal domain of human symplekin
at 1.9 Å resolution as well as the crystal structures of symplekin in
complex with other components of the system. The basis of symplekin's structure
is seven pairs of anti-parallel a helices, similar to the structures of other
scaffolding proteins. The group also discovered how the protein Ssu72 binds to
symplekin and that this interaction stimulates Ssu72's phosphatase activity.
They noted that Ssu72 prefers an unusual substrate: it binds pSer-Pro peptides
in a cis configuration, whereas most proline-directed serine
phosphatases act on the trans configuration.
The researchers suggest that Ssu72's trans configuration preference is
important for 3'-end processing coordination and transcription regulation. This
work was published in the October 7, 2010 issue of Nature.
To learn more about this research see the full scientific highlight
"This will open up the science to a whole new set of users," said SSRL Staff
Scientist Dennis Nordlund, who is part of the team building the instrument.
According to Nordlund, the higher intensity and better resolution offered by
the x-ray Raman instrument make it a very competitive alternative to soft x-ray
spectroscopy. What's more, he says, it overcomes many technical limitations
that come with soft x-ray studies, such as the need to operate under a vacuum.
Read more at: http://today.slac.stanford.edu/feature/2011/ssrl-beamline6-2.asp
Ensuring the safety of SSRL users and staff has been a guiding principle in the
ongoing effort to bring the SPEAR3 accelerator up to its design capacity of 500
mA of current. This principle has never been more evident than during the shift
to top-off injection last year. This operating mode permits the addition of
electrons to the SPEAR3 storage ring while the x-ray beam line injection
stoppers remain open-a radical change from past procedure.
"Before top-off, the injection stoppers had to be inserted for all injections,"
said James Liu, a radiation physicist with SLAC's Radiation Protection
Department, which is charged with providing support and oversight for the
radiological safety of accelerators, beam lines and experiments. The electrons
circulating around the SPEAR3 storage ring, emitting the x-rays needed by SSRL
users, require a periodic boost in the form of more electrons, which are
"injected" into the ring. More-frequent injections support a higher beam
current-more x-rays for user experiments. Read more at: http://today.slac.stanford.edu/feature/2011/safe2011-topoff.asp
On Tuesday, March 22, SSRL Staff Scientist Sam Webb and NASA Astrobiologist
Felisa Wolfe-Simon will present the public lecture "Life Redefined: Microbes
Built with Arsenic" at 7:30 p.m. in SLAC's Panofsky Auditorium. The lecture
will describe the team's research into the first known living organism that
appears to incorporate arsenic into the working parts of its cells, replacing
phosphorus, an element long thought essential for life. This work challenges
the notion that however diverse organisms may be, they are all made of the same
elements: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. More
information on attending the public lecture can be found at:
http://www2.slac.stanford.edu/lectures/default.asp?id=home
In addition, former SSRL Staff Scientist Uwe Bergmann presented the public
lecture "Archaeopteryx: Bringing the Dino-Bird to Life" at SLAC on January 25.
For those who could not attend, the lecture is now available
online. Additional information about this work can also be found in a
January 21 New Scientist article, "Reanimators: Waking the Dino Dead."
The article can be accessed at: http://dx.doi.org/doi:10.1016/S0262-4079(11)60161-9 (subscription required).
The management board of lightsources.org, the international group of
synchrotron/free electron laser communications and public affairs officers, met
last week during the AAAS meeting in Washington, D.C., to discuss new ways to
better serve the light source user communities and promote their scientific
successes to the media, educators, students and the general public. To better
serve its audiences, lightsources.org will be
sending out a brief survey at the beginning of May to assess the usage of the
site and the digital and media needs of the user community. Visit
lightsources.org and give your
feedback!
The February edition of the National User Facility Organization's NUFO News is
now available online. The
edition features a report on NUFO's educational outreach and a description of
an upcoming Capitol Hill user science exhibition.
__________________________________________________________________________
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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