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Newsletter December 2024 | Menu of
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Supporting
Sub-Angstrom Materials Research at
Oak Ridge National Laboratory
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ORNL’s Center for
Nanophase Materials Sciences utilizes Scanning Transmission Electron Microscopy
to analyze atoms in individual nanostructures, permitting the atomic structure
of materials to be seen more clearly at atomic dimensions of smaller than one
ten-billionth of a meter. Critical to this sub-angstrom research is
Negative-Stiffness vibration isolation. |
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Advancements in nanofabrication,
pharmaceuticals, energy and aerospace follow breakthroughs in the understanding
of materials. These breakthroughs unlock unique functionalities that create new
pathways to design future devices.
The Center for Nanophase Materials
Sciences (CNMS) at Oak Ridge National Laboratory (ORNL) is at the forefront of
one of the most powerful capabilities for exploring the nature of materials and
energy. CNMS emphasizes discovery of new materials, and the understanding of
underlying physical and chemical interactions that enable the creation of
nanomaterials.
The center is unique in that it provides a platform for
a vibrant national and international research community that brings together
ORNL research staff, technical support staff, students, postdoctoral fellows
and collaborating guest scientists, accommodating both short-term and long-term
collaborative research projects.
To support this impressive research
capability, CNMS researchers have access to state-of-the-art microscopy
instruments in its Advanced Microscopy Laboratory (AML) for a broad range of
nanoscience research, including nanomaterials synthesis, nanofabrication,
imaging/microscopy/characterization, and theory/modeling/simulation.
Amongst the instruments used for materials research in the ALM are some of
the most advanced Transmission Electron Microscopes (TEM) and Scanning
Transmission Electron Microscopes (STEM)..
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Transmission Electron
Microscopy
TEMs utilize a technique in which a beam of electrons is
transmitted through an ultra-thin specimen, interacting with the specimen as it
passes through. An image is formed from the interaction of the electrons
transmitted through the specimen. The image is magnified and focused onto an
imaging device, such as a fluorescent screen, a layer of photographic film, or
to be detected by a sensor such as a CCD camera. TEMs use phase-contrast, and
therefore, produce results which need interpretation by simulation.
The
ability of electron microscopes to analyze atoms in individual nanostructures
has been limited by lens aberrations, but advances in aberration-correcting
optics have led to greatly enhanced instrument performance and enabled new
techniques in electron microscopy.
Correction of spherical aberration in
the Transmission Electron Microscope, for example, has allowed routine
sub-angstrom resolution imaging. Higher resolution greatly improves sensitivity
to single atoms either lying on a materials surface or inside the bulk
permitting the atomic structure of materials to be seen more clearly, and
allowing light elements to be seen in the presence of heavy atoms. Aberration
correctors have enabled electron probes with sub-angstrom diameters to be used,
making it possible to identify individual atom columns with unprecedented
clarity.
Sensitivity
to Vibration full article... |
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Featured
Product: BM-6 Bench Top Vibration Isolation Platform
- Vertical and horizontal frequencies are weight
dependent.
- The vertical frequency of 2.5 Hz and horizontal
frequency of 1.5 Hz are achieved at the upper limit of the payload range.
- At the lower limits of the payload range, the vertical
frequency is approximately 3.4 Hz and the horizontal frequency is approximately
2.5 Hz.
 The bench top platform offers better performance than a
full size air table in a package only 4.6 inches tall, and without
air!
This vibration isolation platform reaches a new price point and is
extremely easy to use. It offers a 1.5 Hz horizontal natural frequency and a
2.5 Hz vertical natural frequency. There is only one adjustment. There is no
need for air or electricity.
This is the thinnest, most portable, and
most user-friendly isolator ever offered at this level of performance per
dollar.perfect for new generations of small SPM's that require the highest
performance in a very compact system.
Pricing &
Specifications
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DNA, or deoxyribonucleic acid, is the
hereditary material in humans and almost all other organisms. Nearly every cell
in a person's bodpersony has the same DNA, most of which is located in the cell
nucleus. The DNA molecule is packaged into thread-like structures called
chromosomes. Each chromosome is made up of DNA tightly coiled many times around
proteins that support its structure. The information in DNA is stored as a code
made up of four chemical bases: adenine, guanine, cytosine and thymine, which
are present in pairs. Human DNA (i.e., the human genome) consists of about 3
billion DNA base pairs, and more than 99 percent of these base pairs are the
same in all humans. The order, or sequence, of these DNA base pairs determines
the information available for building and maintaining an organism.
DNA Superstructure Research at the University of Texas, Dallas
Research into the functions of DNA has had a significant impact on the
fields of medicine, biotechnology, and the life sciences. One such group that
has been conducting research into DNA is the Physical Genomics Laboratory in
theDepartment of Bioengineering, University of Texas at Dallas. Under the
direction of Dr. Stephen Levene, Professor of Bioengineering, research into the
characterization of biological macromolecules of protein-DNA complexes (DNA
superstructures) has been ongoing for a number of years. Levenes research on
the flexibility and folding of DNA, mediated by protein-DNA interactions, has
led to valuable insights into the physics and organizations of genomes, as well
as gene regulation and genetic recombination. His work has been supported by
the American Cancer Society, Department of Defense, National Institutes of
Health, National Science Foundation and the Texas Higher Education Coordinating
Board.
"I've been working on problems having to do with the
interactions of proteins that organize DNA into tertiary structures that are
biologically important, said Dr. Levene. We are interested in questions that
have to do with DNA superstructures, higher-order structures that organize the
human genome."
"It is not unusual in the genome of many organisms for
genes to be regulated by sequences of DNA that are many thousands of base pairs
away, continued Dr. Levene. In fact, chromosomes are probably organized into
functional units where regulatory elements occupy the same domain and genes
that they regulate. By regulatory elements, I mean sequences of DNA where
proteins bind, and turn on or turn off the genes that are under the control of
those sequences."
"So to that end, for most of my career I have been
interested in what governs those interactions in physical terms, and more
recently, how we can harness our understanding of those interactions to effect
regulation of certain genes and to develop new strategies for diagnostics and
therapeutics, added Dr. Levene." Dr. Levene's team performs experiments in both
ensemble or bulk measurements (making measurements on huge numbers of
molecules), as well as in living cells and on single molecules. Their group can
thus infer the properties of these molecular species either indirectly or more
directly visualize them using tools that resolve optical images of
fluorescently labeled DNA molecules or visualize DNA structures by using
atomic-force microscopy. There are advantages and disadvantages to both
methodologies, so they pursue both of these scales
simultaneously."
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A unique aspect of Dr. Levene's
research is that it combines its experimental research results with advanced
computer models and other types of calculations to address very challenging
physics issues.
"We study very complex problems - such as how DNA
organizes under the constraints of environmental factors - requiring that we
collect data on three-dimensional structure-dependent parameters," explained
Dr. Levene. "For example, with coiling of DNA, which occurs spontaneously,
called supercoiling - to interpret this, good theory is needed, which involves
quite sophisticated physics, and requires using computer-simulation-based tools
and or other computational-modeling approaches. Our group is probably regarded
as one of the leading labs in terms of DNA tertiary structure. But this is
largely because of a strong computational component through our research, which
I think is unique."
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Physical Genomics Laboratory's Leica Thunder fluorescence microscope
system on Minus K MK26 vibration isolation workstation
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| Vibration
problems & negative-stiffness isolation solutions article
continued... |
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