| Vacancy-induced
nanoscale wire structure
in gallium selenide layers
Low-dimensional materials have gained
much attention not only because of the nonstop march toward
miniaturization in the electronics industry but also for the
exotic properties that are inherent in their small size. One
approach for creating low-dimensional structures is to exploit
the nanoscale or atomic-scale features that exist naturally
in the three-dimensional (bulk) form of materials. By this
means, a group from the University of Washington has demonstrated
a new way of creating one-dimensional nanoscale structures
(nanowires) in the compound gallium selenide. In short, ordered
lines of structural vacancies in the material stimulate the
growth of "one-dimensional" structures less than
1 nanometer in width. Full
story.
T. Ohta, D.A.Schmidt, S. Meng, A. Klust,
A. Bostwick, Q. Yu, M.A. Olmstead, and F.S.Ohuchi, "Intrinsic
vacancy-induced nanoscale wire structure in heteroepitaxial
Ga2Se3/Si(001)," Phys. Rev.
Lett. 94, 116102 (2005).
Contact: Taisuke Ohta, TOhta@lbl.gov
Assembly of a
molecular needle,
from the bottom up
Many pathogenic bacteria use a specialized
secretion system to inject virulence proteins directly into
the cells they infect. The injected proteins, by mimicking
host-cell mechanisms, can then subvert normal cellular function,
resulting in diseases ranging from bubonic plague to traveler's
diarrhea. The type III secretion system (TTSS) is a sophisticated
protein complex with an overall shape similar to a hypodermic
needle. More than twenty unique types of proteins are required
for its assembly, most of which are found among a wide variety
of animal as well as plant pathogens. Electron microscopy
(EM) has provided the broad outlines of TTSS structure, but
does not have sufficient resolution to reveal the details
required to understand, and eventually inhibit, the needle's
function. At the ALS, researchers from Canada and the U.S.
performed crystallographic studies of EscJ, the protein that
makes up the needle's ring-shaped base. Their analysis of
the EscJ ring not only presents an atomic snapshot of one
of the earliest structures generated in the TTSS assembly
process, but also reveals features indicative of a role as
the molecular platform for subsequent construction of the
secretion apparatus. Full
story.
Publication about this research: C.K.
Yip, T.G. Kimbrough, H.B. Felise, M. Vuckovic, N.A. Thomas,
R.A. Pfuetzner, E.A. Frey, B.B. Finlay, S.I. Miller, and N.C.J.
Strynadka, "Structural characterization of the molecular
platform for type III secretion system assembly," Nature
435, 702 (2005).
Contact: Natalie Strynadka, natalie@byron.biochem.ubc.ca
Shielding control
process
to undergo reviews
 The
ALS employs redundant layers of protection to shield personnel
from x rays, including engineered controls (e.g., concrete
shielding, hutches, interlocks) as well as administrative
controls (e.g., safety training, procedures, signage). Recently,
the ALS has experienced several incidents in which proper
administrative control procedures for removing shielding were
not followed. Although in each case there was no radiation
in the beamlines and no personnel exposure was possible, the
pattern of the incidents has created a great deal of concern.
Immediate corrective actions were taken to resolve each incident,
but it is apparent that outside reviews are needed to reevaluate
the entire ALS shielding control process.
The first review is already underway:
the Berkeley Lab Radiation Safety Committee has formed a
subcommittee to review and investigate the recent incidents.
The charge of the subcommittee is to "assess the effectiveness
of current shielding control procedures, engineering controls,
training, EH&S staff support, and management oversight
as needed to develop proposed corrective actions to prevent
the likelihood of recurrence." That review began on
December 2, and a draft report is to be completed by early
January. The ALS has also requested that the Laboratory
Director initiate an external review, bringing in safety
experts from other synchrotrons to review the radiation
protection program at the ALS, with particular attention
to the shielding control policies, procedures, and practices.
This review is expected to take place in January.
Contact: Ben Feinberg, B_Feinberg@lbl.gov
SAC surveys progress
and considers future
 Members
of the ALS Scientific Advisory Committee (SAC) met at Berkeley
Lab on December 12 and 13 to hear about the latest ALS initiatives
and advise management on a range of issues, from recommendations
on approved programs to long-range strategic planning for
"ALS II." In welcoming the attendees, Berkeley
Lab Director Steve Chu and Deputy Director Graham Fleming
reiterated their support for future waves of ALS development
and reported that progress was being made in the search for
a new director and on plans for a guest house at Berkeley
Lab. Acting ALS Director Janos Kirz then brought the committee
up to date on recent developments, reporting on, among other
things, the Users' Meeting/workshops, safety issues, and
progress toward facility improvements and beamline development.
ALS Scientific Director Neville Smith then gave a short talk
on
a proposed new metric for assessing Department of Energy light sources. Progress
reports on the PEEM3 and slicing source beamlines were given
by Howard Padmore (Experimental Systems Group Leader), Andreas
Scholl (ALS), and Bob Schoenlein (Materials Sciences Division).
The first afternoon session was devoted
to presentations on "Wave 1" initiatives from the
ALS Strategic Plan: Eli Rotenberg (ALS) described plans for
a nanoARPES beamline and Jeffrey Kortright (Materials Sciences
Division) presented the case for a soft x-ray scattering capability.
The second afternoon session focused on protein crystallography,
with Paul Adams (Berkeley Center for Structural Biology) on
the future of protein crystallography at the ALS and John
Spence (University of Arizona) introducing "serial crystallography,"
a complementary approach that diffracts x rays from beams
of droplets containing the macromolecules under study. Proposal
Study Panel (PSP) chair Yves Idzerda (Montana State University)
rounded out the first day's agenda with the PSP's recommendations
on several candidates for approved-program status. The meeting
continued the second day with talks on theory at the ALS by
Zahid Hussain (Scientific Support Group Leader) and on interactions
between the Center for X-Ray Optics (CXRO) and the ALS by
David Attwood (CXRO). Howard Padmore rounded out the open-session
agenda with a thought-provoking exploration of options for
"ALS II," with improvements in brightness, pulse
length, and beyond. Current
SAC members are listed online.
Contact: Neville Smith, NVSmith@lbl.gov
UEC Corner: Notes
from the Users'
Executive Committee
 The
UEC is here to represent you, so please take the time to
look over
the candidate bios and place
your vote for the next three
UEC members. Voting will be open until December 31st.
Thank you for giving me this opportunity
to represent your interests as
chair of the ALS Users' Executive Committee. My term expires
soon, but
next year, you'll be well represented by the new Chair, Clemens
Heske(Heske@unlv.nevada.edu)
and new Vice-Chair, Tony van Buuren
(vanbuuren1@llnl.gov).
Since budget issues in Washington are
likely to become more important in
the future, the Users' Associations at the light sources
across the
country have formed a group to work on outreach and education
to help
ensure that people understand the importance of the science
that happens
within these facilities. Corie Ralston has agreed to represent
the ALS
UEC in this activity. Please contact her at cyralston@sff.net if you have any questions or
suggestions.
Contact: Greg Denbeaux, GDenbeaux@uamail.albany.edu
Reminder: General-user
proposals
due January 4
 The
User Services Office is still accepting general user proposals
from scientists who wish to conduct research in the general
sciences at the ALS during the running period from July through
December 2006. The deadline for submissions is Wednesday,
January 4, 2006. (This deadline does not apply to protein
crystallography proposals, which have a separate process
and schedule.) Users with existing proposals who wish to
receive beam time during the July through
December 2006 cycle must submit a Proposal Renewal Form.
Scientists with existing proposals that are eligible for
renewal have been sent instructions on how to request a login
and password to access their proposal information and forms.
Proposals can be renewed for up to three six-month cycles
following their initial submission. After three cycles, a
new proposal must be submitted. The following resources are
available for further information:
ALS
User Services Administrator
General-user
proposal process (new proposals)
ALS online forms
ALS
Experiment Report and Request for Beamtime (renewals)
Beamline
information
Proposal
Study Panel (PSP) scores
Contact: alsproposals@lbl.gov
Latest Activity
Report
now posted online
 A
PDF version of the 2004
ALS Activity Report has been posted online. The Activity
Report is published annually and illustrates the depth and
breadth of the ALS scientific program with a selection of
research results. The 2004 edition contains a feature science
article on ultrafast x-ray science at the ALS and a facilities
feature outlining the ALS strategic plan. The report also
summarizes operations, ongoing R&D, educational outreach
efforts, and special events. Printed copies are being mailed
to staff and active users in the ALS database. Others can
request a copy by sending email to alsuser@lbl.gov. Be sure
to include your name, complete mailing address, and the name
of the publication being requested.
Contact: Lori Tamura, LSTamura@lbl.gov
Holiday closure
schedule
 Berkeley
Lab will close on the evening of December 22 and reopen on
the morning of January 2. During the closure, the Lab will
shut down as much heating and ventilating equipment as possible
to reduce costs. (The ALS experiment floor will remain at
normal temperature to prevent damage to sensitive equipment.)
The first user run of 2004 will be January 6–9. The
next issue of ALSNews will be published on January 25. From
all of us at the ALS, have a safe and happy holiday season,
and we'll see you next year!
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