Contents of this Issue:
1. Science Highlight —
Mapping Cellular Nutrient Highways
(contacts: H.W. Pinkett, hpinkett@caltech.edu; D.C. Rees,
dcrees@caltech.edu)
| Structure of ABC transporter HI1470/1: HI1471. |
Though the findings are not immediately applicable, they may prove important in future medicinal uses. For instance, some members of the ABC transporter family are involved in multi-drug resistance. Understanding the mechanism through which substances are transported across cell membranes may be the first step in developing inhibitors to keep medicines inside cells, which would increase a drug's effectiveness. Also, antibiotics could be developed that inhibit the transporters in infectious bacteria, starving them of essential nutrients.
To learn more about this research see the full scientific highlight at:
http://www-ssrl.slac.stanford.edu/research/highlights_archive/abc_rees07.html
2. Science Highlight —
How to Turn Carbon into a Magnet? X-rays and Protons
Give the Answer!
(contact:
H. Ohldag, hohldag@stanford.edu)
The exclusive club of magnetic elements officially has a new member - carbon. Using a proton beam and advanced x-ray techniques, SLAC researchers in collaboration with colleagues from LBNL and the University of Leipzig in Germany have finally put to rest doubts about carbon's ability to be made magnetic.
 | |
| A carbon film is hit by a high-energy proton beam, causing the magnetic moments of the atoms to align around the beam impact area and creating a ring-shaped magnetic pattern that can be imaged with a magnetic-force microscope (left). The x-ray microscope can then be used to "scan" the sample for magnetism associated with other elements. The absence of a ring pattern in scans for cobalt, nickel and iron prove that the sample contains only carbon (right) | |
The results appeared in the May 4 edition of Physical Review Letters.
To learn more about this research see the full scientific highlight at:
http://www-ssrl.slac.stanford.edu/research/highlights_archive/c_ferromagnetism.html
3.
Atoms Fly Apart in Direct Crystal Melting
(contacts:
K. Gaffney, kgaffney@slac.stanford.edu; P. Hillyard, phillyar@slac.stanford.edu)
 |
Short bursts of x-rays provided by the SPPS measured the atomic positions of
the atoms in a semiconductor material. The data, published recently in
Physical Review Letters, revealed that when their bonds destabilized, the atoms
moved apart from each other quickly, as if repelling each other. The
semiconductor material had visible melting damage after being struck by the
laser. "This research provides verification that intense ultra-fast x-ray
sources like the upcoming Linac Coherent Light Source (LCLS) will make possible
the study of previously inaccessible material properties," said SSRL researcher
Patrick Hillyard.
—SLAC Today article by
Heather Rock Woods
4.
New X-ray Photon Correlation Spectroscopy and Lensless Imaging Capabilities
In April scientists began utilizing BL5-2, one of SSRL's newest experimental
stations. This unique facility offers users a range of experimental
capabilities for probing the structure and dynamics of materials at the
nanoscale. Two principal techniques available at this new beam line that take
advantage of SPEAR3's exceptional brightness are x-ray photon correlation
spectroscopy and "lensless imaging." Neither would have been possible with the
earlier generation SPEAR2. BL5-2 uses a special magnet - an elliptically
polarizing undulator - to convert the stored electrons to soft x-rays. Special
properties of the magnetic optics downstream of the undulator cause these soft
x-rays to become "coherent." Coherence is a property of electromagnetic
radiation (of which light or soft x-rays are two examples) which implies an
orderliness of the parameters of the soft x-rays, rather than a randomness.
This orderliness, much like that exhibited by laser light, distinguishes the
soft x-rays produced at this new experimental station from other experimental
stations at SPEAR3 in powerful ways. This opens up investigations into
fluctuating, dynamic states of matter such as magnetism and electrical
properties that are otherwise not possible at SPEAR3.
In many instances, the samples placed in the x-ray beams at SPEAR3 are
crystallized. This has the advantage of presenting a regular, periodic pattern
of molecules to the incoming beam, but the disadvantage that motion of the
molecules is frozen in place. Coherent x-rays, however, enable researchers to
probe samples that do not have regularly arranged, periodic structures-such as
molecules that resist crystallization-and can identify individual elements and
their dynamic states within a single sample.
During the upcoming annual shutdown later this summer (August-October), the
experimental stations at BL5-2 as well as BL5-1 will be relocated to a
permanent home on the new beam line 13. A new undulator on BL13 will offer an
even brighter source of coherent x-rays, and new control systems will provide
an operational platform especially optimized to take full advantage of the
potential of SPEAR3. And once SPEAR3 begins operating at the design current of
500 mA (as is planned to begin partially during the next year's run),
experiments at this station will take one-fifth the time as with the 100 mA in
use today.
This new suite of tools also shares many similarities with the LCLS. The
overlap is such that much work has been accomplished toward understanding how
to best capitalize on the unique imaging capabilities of the LCLS. SPEAR3's
continuing evolution is opening new doors at SSRL in the type of science
available to our users now and in the future.
At SSRL, Jim was most often found at the x-ray scattering beam lines 2-1, 7-2,
and 11-3. He used these beam lines to look at the damage induced in silicon
crystals during ion-implantation doping. This doping technology is a critical
component of modern semiconductor manufacturing, but the electrical properties
of the doped material, and the diffusion of the dopants within the silicon,
depend sensitively on the nature of the damaged lattice. Jim used his
connections at Intel to obtain a variety of excellent samples, and used
grazing-incidence diffuse x-ray scattering, along with high-resolution x-ray
diffraction, Hall-effect measurements, and transmission electron microscopy to
gain insight into the damage caused by implantation, its response to laser
annealing, and the final distribution of dopants in the silicon lattice.
According to SSRL colleague Apurva Mehta, "When we had beam time Jim would be
at the beam line every morning until early evening and then often come back for
a couple of hours after dinner to pour over data and guide the next set of
experiments. And often he would take some of the data "home" - i.e., get it
transferred to his home directories and often come next morning with some
preliminary analysis". Not surprisingly, this work led to nearly a dozen
scientific papers.
In addition to being a tireless and creative scientist, Jim was an
exceptionally warm and friendly colleague. He served as mentor to a number of
postdocs and graduate students during his time at SSRL, and collaborated with
several other SSRL staff members. In 2005, his colleagues from around the
world gathered to celebrate his 80th birthday with a workshop on x-ray
microdiffraction. He leaves behind a formidable scientific legacy, a wide
circle of friends, and an extensive family.
A memorial service will be held for Jim on Saturday, June 9, at 3:00 p.m., at
Saint Raymond's Catholic Church, located at 1100 Santa Cruz Avenue, Menlo Park,
CA. All who wish to remember Jim are welcome to attend.
Based on the comments received, the workshop was a big success. All the
attendees came away with new knowledge about how to efficiently collect data at
SSRL's scattering beam lines. Copies of all the talks have been posted at:
—At SSRL
Submit new macromolecular crystallography proposals by July 1, 2007. For beam
time before fall 2007, users can submit a Rapid Access proposal or contact L.
Dunn (lisa@slac.stanford.edu) for more information.
Rapid access proposals for structural molecular biology x-ray absorption
spectroscopy experiments on BL7-3 can be submitted at any time. Periodic
blocks are 6 shifts of beam time are set aside to allow new and current
biological XAS users to perform feasibility tests. For questions, please
contact Serena DeBeer George (serena@slac.stanford.edu).
Rapid access proposals for structural molecular biology small angle x-ray
scattering experiments on BL4-2 can also be submitted at any time.
5.
June 9 Memorial Service for Jim Patel
On March 3, SSRL lost an esteemed colleague with the death of Jamshed (Jim) R.
Patel at the age of 81. Born and educated in India, Jim spent most of his
career at Bell Laboratories, during that institution's years as a dominant
scientific force. After retiring from Bell Labs, Jim moved to California in
1994, consulted at Intel Corporation, and took a joint position at SSRL and at
the Advanced Light Source in Berkeley.
Jim's scientific interest throughout his career focused on defects in crystals.
X-ray diffraction was the primary tool that he used. Starting with laboratory
x-ray sources, Jim progressed to using 2nd and eventually 3rd generation
synchrotron sources. Most recently, Jim was closely involved with creating and
using the x-ray microdiffraction beam line 7.3.3 at ALS, studying
electromigration-induced plasticity in interconnects on microchips, and strain
associated with grain and domain boundaries in superconductors.
6.
Wrap-up on Second Annual SSRL School on Synchrotron X-ray Scattering
Techniques in Materials and Environmental Sciences
(contacts:
S. Webb, samwebb@slac.stanford.edu;
C. Condron, condron@slac.stanford.edu;
M. Toney, mftoney@slac.stanford.edu;
J. Bargar, bargar@slac.stanford.edu)
The second annual SSRL School on Synchrotron X-ray Scattering Techniques in
Materials and Environmental Sciences was held at SSRL on May 15-17, 2007. The
aim of this workshop was for students, postdocs and researchers to gain
practical knowledge in x-ray scattering methods with an emphasis on information
that cannot be found in text books. More than 45 researchers, mostly graduate
students and postdocs, attended the workshop. The first day consisted of
introductory lectures on x-ray diffraction, how to get the most data out of
your beam time, and how to apply various techniques. The second and third days
involved "on-the-experiment" training at four of SSRL's beam lines (1-4, 2-1,
11-3, and 7-2), followed by data analysis demonstrations and Q&A sessions. The
practical sessions were well attended, and all those that attended benefited
greatly from these demonstrations.
http://www-ssrl.slac.stanford.edu/conferences/workshops/scatter2007/talks.php
7.
Upcoming Schools, Users' Meetings and Workshops
http://photonscience.slac.stanford.edu/pulse/uxss2007/index.php—At Other DOE Light Sources
http://www.nsls.bnl.gov/users/meeting/2007/
8.
User Award Nominations due in August
http://www-ssrl.slac.stanford.edu/kleinaward.html
http://www-ssrl.slac.stanford.edu/spiceraward.html
http://www-ssrl.slac.stanford.edu/lytleaward.html
9.
User Administration Update
(contact: C. Knotts,
knotts@slac.stanford.edu)
http://www-ssrl.slac.stanford.edu/users/user_admin/px_proposal_guide.html
http://www-ssrl.slac.stanford.edu/users/user_admin/bio_xas_rapidaccess.html
http://www-ssrl.slac.stanford.edu/users/user_admin/bio_saxs_rapidaccess.html
10.
Photon Science Job Opportunities
A number of positions are currently available at SSRL and LUSI.
Please refer to the Photon Science Job Openings page for more information about
these job opportunities.
http://photonscience.slac.stanford.edu/jobs.php
__________________________________________________________________________
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.
__________________________________________________________________________
To leave the SSRL-HEADLINES distribution, send email as shown below:
To: LISTSERV@SSRL.SLAC.STANFORD.EDU Subject: (blank, or anything you like)
The message body should read
SIGNOFF SSRL-HEADLINES
That's all it takes. (If we have an old email address for you that is forwarded to your current address, the system may not recognize who should be unsubscribed. In that case please write to ssrl-headlines-request@ssrl.slac.stanford.edu and we'll try to figure out who you are so that you can be unsubscribed.)
If a colleague would like to subscribe to the list, he or she should send To: LISTSERV@SSRL.SLAC.STANFORD.EDU and use the message body
SUBSCRIBE SSRL-HEADLINES
|
SSRL Welcome
Page | Research
Highlights | Beam Lines | Accel
Physics
User Admin | News & Events | Safety Office |
