Transcript Document 7142573

Materials
Fast but smooth - Cornell group discovers new
growth method for smoother organic films
at CHESS
DMR-0225180
Aram Amassian, James Engstrom, Todd W. Schroeder, Aravind S. Killampalli,
George Malliaras, Joel D. Brock, Arthur Woll and Detlef Smilgies, Cornell
The Materials Research Society (MRS) awarded a
“best poster prize” to four collaborative groups at
Cornell for their work “In-situ Real-Time
Synchrotron Study of Small Molecule Organic Thin
Film Growth from Hyperthermal Molecular
Beams.” The poster presented some of the firstever results the team obtained using a new
supersonic molecular beam growth chamber in the
G3 X-ray station at CHESS. Pentacene thin films
are currently the organic semiconductors with the
highest field effect mobility measured – even
exceeding that of amorphous silicon. Growing
high quality organic thin films, however, presents
new challenges quite different from those found
(and overcome) in the highly mature field of silicon
device manufacture.
“These findings raise the distinct possibility
that some pentacene polymorphs may be
synthesized with ultra-flat surface
morphology…”
2007_1
Pentacene film “terrain”
viewed by atomic-force
microscope (AFM).
Shown is a fairly rough
film deposited under 3D
growth conditions –
smooth films resulted
from faster deposition
rates. (Below) The
research group receives
the first place poster
award from the MRS
selection committee.
Biophysics
X-ray Study Reveals How HIV Infiltrates
Cell Membranes
at CHESS
DMR-0225180
Stephanie Tristram-Nagle and John F. Nagle (Carnegie Mellon)
Researchers have used small-angle x-ray scattering at
CHESS to uncover details about HIV infection.
Carnegie Mellon University scientists have made an
important discovery that aids the understanding of why
HIV enters immune cells with ease. The researchers
found that after HIV docks onto a host cell, it
dramatically lowers the energy required for a cell
membrane to bend, making it easier for the virus to
infect immune cells.
“These findings provide vital data to conduct
future computer simulations of HIV dynamics
to help further drug discovery and prevent
deadly infections.”
“HIV fusion peptide dramatically decreases the
amount of energy needed to bend a cell membrane.
This helps membranes curve, a necessary step for HIV
to fuse with an immune cell as it infects it,” explained
Tristram-Nagle. The work was supported by the
General Medicine Institute of the NIH (GM 44976)
and CHESS. [Parts from CMU Press Release]
2007_2
Hypothetical fusion
intermediates showing how
a pore can be opened in a
cellular membrane. Lipid
bilayer surfaces are
indicated by solid lines.
Dotted lines in the
hydrocarbon interior divide
the bilayers into monolayers.
A) Contact of the virus and
target membranes B) Stalk
that allows lipid mixing C)
Hemifusion diaphragm (HD)
and D) Pore opened.
Published in Biophysical
Journal, BioFAST: First
Published May 25, 2007,
doi:10.1529/biophysj.107.10
9181;
Amorphous Organic Films Show Medium-range Order
that Bodes Well for Future Organic Devices
Chemistry
at CHESS
DMR-0225180
Daniel R. Blasini, Jonathan Rivnay, Detlef-M. Smilgies, Jason D. Slinker,
Samuel Flores-Torres, Héctor D. Abruña and George G. Malliaras, Cornell
The performance of devices such as organic light
emitting diodes (OLEDs) that depend on thin films are
strongly correlated with the film's microstructure. While
single crystal films generally exhibit the highest
transport rates and quantum efficiencies, there are no
cost effective methods to deposit such films over large
areas. The use of polycrystalline films presents great
challenges due to their high surface roughness and the
fact that grain boundaries serve as efficient trapping and
recombination sites resulting in dramatic degradation of
performance. Results from CHESS provide a first
characterization of a nominally amorphous molecular
semiconductor thin film, and indicate that ordering
actually occurs on an intermediate range, with crystalline
domains in the range of a few nanometers.
“…film morphology affects device performance.
Such intermediate range order [discovered here] has
been a hot topic in the community studying glassy
materials in recent years.”
2007_3
The grazing-incidence x-ray scattering from films of
[Ru(bpy)3]2+ (PF6–)2. Data were collected at an
incident angle = 0.13° to enhance the weak thin
film scattering signal over the diffuse scattering
from the substrate.
[From Journal of Materials Chemistry Advance
Articles DOI: 10.1039/b700505a, 2007].
Man-made Proteins Could Be More
Useful than Real Ones
Biology
at CHESS
DMR-0225180
Douglas S. Daniels, E. James Petersson, Jade X. Qiu, and Alanna Schepartz,
Yale University
Howard Hughes investigators and CHESS researchers
have constructed a protein out of amino acids not found
in natural proteins, discovering that they can form a
complex, stable structure that closely resembles a natural
protein. "The fundamental insight from this study is that
β-peptides can assemble into structures that generally
resemble natural proteins in shape and stability,"
Schepartz said. She added that their findings about the
structure of the molecule that she and her colleagues
synthesized will help scientists construct more elaborate
β-peptide assemblies and ones that possess true biologic
function. Such β-peptides could also be designed as
pharmaceuticals that would be more effective than
natural protein drugs, because the enzymes that degrade
natural proteins would not affect them. [From: ACS
Chemical & Engineering News, February 5, 2007
volume 85]
“Their findings could help scientists
design drugs that look and act like real
proteins but won't be degraded by
enzymes or be targeted by the immune
system, as natural proteins are.”
(At right) Structure of the Zwit-1F beta-peptide bundle as
determined by x-ray crystallography. The bundle contains eight
copies of the beta-peptide Zwit-1F with parallel and antiparallel
helices in like and unlike colors, respectively. [Image: Douglas S.
Daniels] From: J. Am. Chem. Soc., 129 (6), 1532 -1533, 2007
2007_4
X-ray Mapping of Heterogeneous
Copper Distribution in Vineyard Soils
Astrid R. Jacobson, Sylvie Dousset, Francis Andreux, and
Philippe C. Baveye, Cornell and Universite´ de Bourgogne, France
Surprisingly, microorganisms with a high sensitivity to toxic
heavy metals are routinely found in highly contaminated
soils. Also puzzling are observations that the response of
microorganisms to metal contamination of soils varies
significantly from one investigation to another. One
explanation could be that metals are heterogeneously
distributed at spatial scales relevant to microbes and that
microorganisms are able to avoid zones of intense
contamination. This work aimed to assess the microscale
distribution of Cu in a vineyard soil using electron
microprobe and synchrotron X-ray microfluorescence
spectroscopy. The results show that the Cu distribution is
strongly heterogeneous at all scales of observation. It also
suggests that current soil sampling protocols, typically
leading to bulk contaminant concentrations in the whole
root zone, may be largely misleading in terms of the
ecotoxicology of metal contaminants in soils.
(Right) Scanned image of a 1-mm
thick thin section of the VR-450 soil
(left) showing Cu and O content (EM
micrographs shown). [From: Env.
Sci. & Tech., 41 (18) 2007]
2007_5
Environmental
Science
at CHESS
DMR-0225180
“Until just a few years ago, no
available experimental technique
allowed the mapping of elemental
distribution in geological samples or
soil thin sections at micron-scale
resolution over even millimetric, let
alone centrimetric, areas. Fortunately,
the advent of microfocused
synchrotron-based X-ray fluorescence
spectroscopy has since made this type
of measurement feasible…”
Materials
Smaller is More Bizarre in the Nanoworld of Ceria
Zhongwu Wang, Sudipta Seal, Swanand Patil, Chang-Sheng Zha, Qing Xue
(CHESS, U. Central Florida, CIW and Intel Corp.)
at CHESS
DMR-0225180
Homogeneous Stress field
Across entire single particle
As we learn more and more about the small,
nanoscale world around us, scientists and
engineers are proposing and building new devices
O2
COMPRESSION
and components from nanoscale materials
daily. Before we start building nano-houses and
superfluid
nano-robots, though, lots of challenges and
+
hurdles stand in our way. Foremost among them
oxygen
is a common observation that many materials
O2
Oxygen
vacancies
behave in unpredictable and bizarre ways when
Producing quasi-hydrostatic state
they get very small. One such material is cerium
High-pressure causes 3 nanometer ceria (cerium oxide)
oxide, or ceria (CeO2), now widely investigated
particles to release oxygen. The oxygen forms a gaseous
for future energy applications as either a catalyst
medium surrounding the nanoparticles and the vacancyor as a storage medium in solid oxide fuel
filled surface layer behaves like a superfluid.
cells. Using data from CHESS, these researchers
[From “Anomalous Quasihydrostaticity and Enhanced
show that very different phenomena are observed
Structural Stability in 3 nm Nanoceria,” web published in
when 3 (versus 10) nanometer crystals of ceria are
Journal of Physical Chemistry C Letters (7/21/2007 10.1021/jp074909g).]
loaded into the diamond cell.
Ceria is also promising for new biomedical applications such as defending cells from reactive
oxygen species or protecting normal cells during radiation treatments that destroy tumor cells.
2007_6
New X-ray Microscope Uncovers Mysteries in
Famous Wyeth Painting
Art History
at CHESS
DMR-0225180
Arthur Woll, Sol M. Gruner, Don Bilderback, Jennifer Mass, Noelle Ocon,
Christina Bisulca, Matt Cushman (CHESS, Cornell, Winterthur Museum, U.
Delaware, North Carolina Museum of Art)
Famous or not, many artists put several paintings on a
single canvas – sometimes strictly for convenience,
but occasionally also to conceal previous
work. Curious art historians want to dig out all
possible details about paintings and their
producers. Historians cannot afford, though, to risk
damaging precious works of art. To aide their efforts a
new instrument has been developed at Cornell, called a
“Confocal X-ray fluorescence (CXRF) microscope,”
which lets art historians uncover minute details about
buried features without inflicting any damage onto
precious works of art. This device focuses an X-ray
beam onto a painting and then collects the fluorescent
X-rays given off by the chemicals in the various paint
layers. Each color of paint will produce a
characteristic fluorescence spectrum, a unique
“chemical fingerprint.”
“The Confocal XRF microscope at CHESS is
the first of its kind at a powerful synchrotron
source in the United States…”
2007_7
1918 illustration for the story, "Mildest Mannered Man" by
Ben Ames Williams (Everybody's Magazine) hidden beneath
the 1924 N.C. Wyeth painting "Family Portrait" (Brandywine
River Museum). Inset shows preliminary x-ray data imaging
Cadmium (found in yellow paint) in the face of the villain,
Slag Harshmeyer.
(Right) Detail of face
revealed by zinc
fluorescence signal.
Researchers Unlock Key Information about
Cystic Fibrosis and Tuberculosis
Biology
at CHESS
DMR-0225180
Eric J. Drake, Jin Cao, Jun Qu, Manish B. Shah,Robert M. Straubinger, and
Andrew M. Gulick, Hautpman-Woodward Medical Research Institute
The structure of a novel protein in the bacterium that is
the most persistent pathogen in cystic fibrosis (CF)
patients has been solved. Hauptman-Woodward Institute
scientists Dr. Andrew Gulick, Eric Drake and Dr. Manish
Shah, in collaboration with researchers at SUNY Buffalo
and the New York State Center of Excellence in
Bioinformatics and Life Sciences have made this
significant discovery, which was published in the current
issue of the Journal of Biological Chemistry. The study
is the first structural characterization of the PA2412
protein, which is needed for the bacterium to obtain iron
from its environment. Equivalent proteins are present,
and required, in many bacteria including the pathogen
that causes tuberculosis. Gulick's work is funded by the
National Institutes of Health and by a grant from the
Dreamcatcher Foundation in Buffalo, NY.
Crystallographic data were collected at the Cornell High
Energy Synchrotron Source (CHESS), which is
supported by the National Science Foundation and the
National Institutes of Health. (Parts excerpted from
Hauptman-Woodward Medical Research Institute news.)
2007_8
Sequence conservation of the MbtH-like family. An
amino acid sequence alignment of several family
members is shown. Those residues conserved in
>95% of the family members are shown.
[From: Journal of Biological Chemistry, Jul 2007; 282:
20425 – 20434]
“[This research] unlocks key information that
may help lead to designs for antibiotic to help
prevent infection in Cystic Fibrosis and
Tuberculosis patients…”
New Method from CHESS to Record
Thermal Distortions of X-ray Optics
Engineering
at CHESS
DMR-0225180
Peter Revesz, Alexander Kazimirov
and Ivan Bazarov, CHESS
Not a single biologist, chemists or physicist would use synchrotron radiation
sources if not for high-quality optical elements that select, shape, and focus highpower, high-intensity x-ray beams onto their specimens. Modern insertion devices
driven produce x-ray broadband power densities equal to those produced by arc
welders! While it has long been possible to use Infra-Red cameras to record the
elevated temperatures of crystals and mirrors being hit by synchrotron beams, it
has not yet been possible to image the actual physical distortions of the mirror
surfaces or diffraction planes. Heated surfaces expand and the so-called “thermal
bumps” cause x-ray beam divergences to grow and peak photon intensities to
drop, and contribute in general to degrading of the longevity and performance of
optical elements and beamlines. Recently, three scientists at CHESS devised a
new method to view surface distortions under direct synchrotron heating.
“…first ever in-situ
three-dimensional
topographs of the
synchrotron x-ray
beam footprint.”
2007_9
(Left) When a high-power
synchrotron x-ray beam hits the
optic, the surface develops a
“thermal bump” and the video
image of the dots becomes
distorted. The displacements of
the dots from their “cold” positions
can be used to build a gradient
vector map of the heated surface
– somewhat similar to distorting a
pin cushion. Mathematical
inversion lead to displacement
images (below). [From Nuclear
Instruments and Methods in
Physics Research A 576 (2007)
422–429.]
Adeno-associated virus (AAV) is a potentially useful
DNA carrier to correct genetic defects
Biology
at CHESS
DMR-0225180
L. Govindasamy, W. Padron, R. McKenna, N. Muzyczka, N. Kaludov, J. A.
Chiorini, and M. Agbandje-McKenna, U. Florida
The adeno-associated viruses (AAVs) can package and
deliver foreign DNA into cells for corrective gene
delivery applications. The AAV serotypes have distinct
cell binding, transduction, and antigenic characteristics
that have been shown to be dictated by the capsid viral
protein (VP) sequence. To understand the contribution of
capsid structure to these properties, the AgbandjeMcKenna group determined the crystal structure of AAV
serotype 4 (AAV4 using the CHESS F1 station. AAV4
shares similarities with AAV2 (first determined the
Chapman group at CHESS,) such as core regions of the
viral capsid proteins (VPs), and the packing of VPs on
the viral surface, while the shapes, and charges, of
surface features differ substantially. Specific amino
acids involved in receptor recognition have been
identified, as well as locations in which loops could be
inserted or deleted without affecting VP packing.
“…this information will be very helpful in
guiding genetic engineering of AAVs and
potential corrective gene delivery strategies…”
2007_10
Depth-cued surface representation of the AAV4 capsid
crystal structure viewed down the icosahedral twofold
axis. A viral asymmetric unit is depicted by a triangle
(in white).
[From: J. Virology (2006), 80, 11556-11570]
Second CHESS Ph. D. Thesis Prize to
Chemist Daniel Blasini
“Fuel cells as energy sources” and “organic light-emitting
diodes” are keen interests of one of Cornell’s newlyminted physical chemists, Daniel Blasini. His graduate
work at Cornell won the second annual Ph. D. Thesis Prize
by the Cornell High Energy Synchrotron Source
(CHESS). His graduate thesis, “Characterization of thin
films and thin film phenomena in electrochemically active
systems via x-ray methods,” documented five years of
work focused on detailed surface structure and function of
materials used in the high technology world of fuel cells,
batteries and displays. During this time, Daniel developed
methods and instruments to probe the physical chemistry
of newly synthesized materials using powerful synchrotron
x-ray beams. His work on organic light-emitting diode
materials was recently published and highlighted in the
Journal of Materials Chemistry (17 (15):1458-61, 2007).
“Blasini… is the first Puerto Rican graduate from
among the initial few dozen G-line graduate
students studying at CHESS.”
2007_11
Outreach &
Education
at CHESS
DMR-0225180
REU Undergraduates Innovate for Future
Accelerator-based Light Sources
Outreach &
Education
at CHESS
DMR-0225180
“Like the 150 students over the decade before
them, this year’s applicants found no time for a
leisurely pace on the job…”
It was certainly no vacation for 14 undergraduates who
chose to spend their summer working on a wide variety of
projects covering areas of particle physics, accelerator
design and ways to improve x-ray optics for synchrotron
research. The students were quickly integrated into real
research and development on forward looking projects
such as the International Linear Collider and the Energy
Recovery Linac (ERL), a new super-brilliant x-ray source
being developed at Cornell. Topics of projects included
“Laser Shaping for High-Brightness Photoelectron
Sources,” “Development of Control System and
Applications for Modern Accelerators,” “Outgassing Of
Stainless Steel Vacuum Chambers And The Vacuum
Pumping Speed And Capacity Evaluation Of A Titanium
Sublimation Pump,” and ”Heat Bump Modeling in High
Heat-Load X-Ray Optics.” The last, by Emmett Windisch,
a rising senior at Wayne State University, tied in nicely
with engineering work on high-heat load x-ray optics by
CHESS scientists (lower image at right).
2007_12
(Top) REU students and RET teacher (bottom,
left) in group photo. (Bottom) Model of heat
deposition in a water-cooled x-ray optics crystal,
by Emmett Windisch (top right in photo).
As RET, high-school teacher sees the
world through glass capillaries
Outreach &
Education.
at CHESS
DMR-0225180
“She developed new analytical tools for
capillary fabrication that will prove useful
for years to come to help achieve even
smaller x-ray microbeams.”
“Working on glass” is what high school teacher
Courtney Couvreur, mathematics major in college,
decided to do with the first summer after a master’s
degree program in secondary education from the
University of Michigan. For years the CHESS
capillary optics group has pioneered the process of
heating and tapering hollow glass tubes to create a
sort-of “funnel” for focusing x-ray beams down to
micron-sized spots. X-ray microbeams have
numerous applications such as studying buried layers
of paint for art historians, uncovering air pollution by
studying tree rings in old timbers, and focusing x-ray
beams onto tiny micron-sized protein crystals to help
solve puzzles in membrane biology. Achieving
perfect elliptical capillary shapes are needed for
efficient focusing. Courtney developed a way to
analyze downstream x-ray images to determine how
the capillary shapes are not perfect.
2007_13
Courtney Couvreur, above right and below center, shows farfield x-ray images from a glass capillary (black and white
Polaroid photo) and compares them to color images generated
from here modeling program. The audience was a group of
RET teachers who were hosted for the summer by the Cornell
Center for Materials Research.