From ORNL: “ORNL microscopy uncovers “dancing” silicon atoms in graphene”

April 3, 2013
Morgan McCorkle

“Jumping silicon atoms are the stars of an atomic scale ballet featured in a new Nature Communications study from the Department of Energy’s Oak Ridge National Laboratory.

Oak Ridge National Laboratory researchers used electron microscopy to document the ‘dancing’ motions of silicon atoms, pictured in white, in a graphene sheet.

The ORNL research team documented the atoms’ unique behavior by first trapping groups of silicon atoms, known as clusters, in a single-atom-thick sheet of carbon called graphene. The silicon clusters, composed of six atoms, were pinned in place by pores in the graphene sheet, allowing the team to directly image the material with a scanning transmission electron microscope.

The ‘dancing’ movement of the silicon atoms was caused by the energy transferred to the material from the electron beam of the team’s microscope.

‘It’s not the first time people have seen clusters of silicon,’ said coauthor Juan Carlos Idrobo. ‘The problem is when you put an electron beam on them, you insert energy into the cluster and make the atoms move around. The difference with these results is that the change that we observed was reversible. We were able to see how the silicon cluster changes its structure back and forth by having one of its atoms ‘dancing’ between two different positions.’”

See the full article here.

ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.

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From ORNL: “ORNL begins implementation of new californium-252 production contract”

Oak Ridge National Laboratory

Feb. 28, 2013
Bill Cabage

The Department of Energy’s Oak Ridge National Laboratory – home of one of only two reactor facilities in the world capable of producing californium-252 (Cf-252) – has begun implementing a new six-year contract between the DOE Isotope Program and industry to make this unique and versatile radioisotope.

The new contract follows the successful completion of a four-year Cf-252 program under an agreement with a consortium of industries that use the neutron emitting radioisotope for a number of applications that focus mostly on analysis, detection and nuclear energy.

‘Californium-252 serves as a unique, portable neutron source,’ said Julie Ezold, who manages ORNL’s Cf-252 production program. ‘A cross-cut of industries including coal, oil and mineral companies rely on it for critical applications, and it is used in defense and national security applications.’”

See the full article here.

ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science.

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From Oak Ridge Lab: “ORNL scientists solve mercury mystery, Science reports”

Oak Ridge National Laboratory

Saturday, February 9, 2013
Ron Walli

“By identifying two genes required for transforming inorganic into organic mercury, which is far more toxic, scientists today have taken a significant step toward protecting human health.

Image by Thomas Splettstoesser

The question of how methylmercury, an organic form of mercury, is produced by natural processes in the environment has stumped scientists for decades, but a team led by researchers at Oak Ridge National Laboratory has solved the puzzle. Results of the study, published in the journal Science, provide the genetic basis for this process, known as microbial mercury methylation, and have far-reaching implications.

‘Until now, we did not know how the bacteria convert mercury from natural and industrial processes into methylmercury,’ said ORNL’s Liyuan Liang, a co-author and leader of a large Department of Energy-funded mercury research program that includes researchers from the University of Missouri-Columbia and University of Tennessee.

Ultimately, by combining chemical principles and genome sequences, the team identified two genes, which they named hgcA and hgcB. Researchers experimentally deleted these genes one at a time from two strains of bacteria, which caused the resulting mutants to lose the ability to produce methylmercury. Reinserting these genes restored that capability, thus verifying the discovery.

‘This newly gained knowledge will allow scientists to study proteins responsible for the conversion process and learn what controls the activity,’ said Liang, adding that it may lead to ways of limiting methylmercury production in the environment.”

See the full article here.

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From ORNL: ” ‘Zoomable’ map of poplar proteins offers new view of bioenergy crop”

Oak Ridge National Laboratory

Tuesday, January 29, 2013
Morgan McCorkle

“Researchers seeking to improve production of ethanol from woody crops have a new resource in the form of an extensive molecular map of poplar tree proteins, published by a team from the Department of Energy’s Oak Ridge National Laboratory.

An extensive molecular map of poplar tree proteins from Oak Ridge National Laboratory offers new insight into the plant’s biological processes. Knowing how poplar trees alter their proteins to change and adapt to environmental surroundings could help bioenergy researchers develop plants better suited to biofuel production. The study is featured on the cover of January’s Molecular and Cellular Proteomics. No image credit.

Populus, a fast-growing perennial tree, holds potential as a bioenergy crop due to its ability to produce large amounts of biomass on non-agricultural land. Now, a study by ORNL scientists with the Department of Energy’s BioEnergy Science Center has provided the most comprehensive look to date at poplar’s proteome, the suite of proteins produced by a plant’s cells. The study is featured on the cover of January’s Molecular and Cellular Proteomics.

‘The ability to comprehensively measure genes and proteins helps us understand the range of molecular machinery that a plant uses to do its life functions,’ said ORNL’s Robert Hettich. ‘This can provide the information necessary to modify a metabolic process to do something specific, such as altering the lignin content of a tree to make it better suited for biofuel production.’”

See the full article here.

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From ORNL Lab: “ORNL research paves way for larger, safer lithium ion batteries”

Friday, January 25, 2013
Morgan McCorkle

“Looking toward improved batteries for charging electric cars and storing energy from renewable but intermittent solar and wind, scientists at Oak Ridge National Laboratory have developed the first high-performance, nanostructured solid electrolyte for more energy-dense lithium ion batteries.

ORNL researchers developed a nanoporous solid electrolyte (bottom left and in detail on right) from a solvated precursor (top left). The material conducts ions 1,000 times faster than its natural bulk form and enables more energy-dense lithium ion batteries.

Today’s lithium-ion batteries rely on a liquid electrolyte, the material that conducts ions between the negatively charged anode and positive cathode. But liquid electrolytes often entail safety issues because of their flammability, [read this, Boeing] especially as researchers try to pack more energy in a smaller battery volume. Building batteries with a solid electrolyte, as ORNL researchers have demonstrated, could overcome these safety concerns and size constraints.

‘To make a safer, lightweight battery, we need the design at the beginning to have safety in mind, said ORNL’s Chengdu Liang, who led the newly published study in the Journal of the American Chemical Society.”

See the full article here.

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From ORNL: “ORNL pushes the boundaries of electron microscopy to unlock the potential of graphene”

Nov. 15, 2012
Jennifer Brouner

“Electron microscopy at the Department of Energy’s Oak Ridge National Laboratory is providing unprecedented views of the individual atoms in graphene, offering scientists a chance to unlock the material’s full potential for uses from engine combustion to consumer electronics.

Graphene is an atomic-scale honeycomb lattice made of carbon atoms. Wikipedia

Graphene crystals were first isolated in 2004. They are two-dimensional (one-atom in thickness), harder than diamonds and far stronger than steel, providing unprecedented stiffness, electrical and thermal properties. By viewing the atomic and bonding configurations of individual graphene atoms, scientists are able to suggest ways to optimize materials so they are better suited for specific applications.

In a paper published in Physical Review Letters, a team of researchers from Oak Ridge National Laboratory and Vanderbilt University used aberration-corrected scanning transmission electron microscopy to study the atomic and electronic structure of silicon impurities in graphene.

‘We have used new experimental and computational tools to reveal the bonding characteristics of individual impurities in graphene. For instance, we can now differentiate between a non-carbon atom that is two-dimensionally or three-dimensionally bonded in graphene. In fact, we were finally able to directly visualize a bonding configuration that was predicted in the 1930s but has never been observed experimentally,’ said ORNL researcher Juan-Carlos Idrobo. Electrons in orbit around an atom fall into four broad categories – s, p, d and f – based on factors including symmetry and energy levels.

‘We observed that silicon d-states participate in the bonding only when the silicon is two-dimensionally coordinated,’ Idrobo said. ‘There are many elements such as chromium, iron, and copper where the d-states or d-electrons play a dominant role in determining how the element bonds in a material.”

See the full article here.

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From Oak Ridge Lab: “Where atoms are, and what they do”

Neutron Scattering for Novices workshop fascinates scientists with a newfound analytical tool

May 23, 2012
Agatha Bardoel

“A 100-million-year old fossil from Antarctica’s tropical age, revealed by neutron imaging, fascinated participants at the Neutron Scattering for Novices workshop at Oak Ridge National Laboratory’s Spallation Neutron Source (SNS), held May 16.

Spallation Neutron Source. Aerial view of SNS

The TOPAZ detector array tank shown in 2009, before its installation in the Spallation Neutron Source’s target building. TOPAZ is one of the SNS instruments under the Office of Science’s just completed SING project.

Robert McGreevy, ORNL’s deputy associate lab director for Neutron Sciences showed the geological sample as an example of what advanced neutron techniques can do — in this case, nondestructively see what’s inside an ancient fossil.

The workshop, organized by the University of Tennessee-ORNL Joint Institute for Neutron Sciences (JINS), introduced neutron scattering techniques to scientists who have little or no experience with neutrons in research. Kelly Beierschmitt, associate laboratory director for Neutron Sciences at Oak Ridge National Laboratory, invited faculty members, research scientists, and postdocs, as well as senior Ph.D. students, to become neutron users at facilities such as the SNS and the High Flux Isotope Reactor (HFIR) at ORNL.

Scientists from across the United States and one Chinese university attended the one-day intensive event.

See the full article here.

ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science.

From ORNL: “ORNL microscopy yields first proof of ferroelectricity in simplest amino acid “

Oak Ridge National laboratory

Morgan McCorkle
Thursday, April 19, 2012

“The boundary between electronics and biology is blurring with the first detection by researchers at Department of Energy’s Oak Ridge National Laboratory of ferroelectric properties in an amino acid called glycine.

A multi-institutional research team led by Andrei Kholkin of the University of Aveiro, Portugal, used a combination of experiments and modeling to identify and explain the presence of ferroelectricity, a property where materials switch their polarization when an electric field is applied, in the simplest known amino acid—glycine.

ORNL researchers detected for the first time ferroelectric domains (seen as red stripes) in the simplest known amino acid – glycine.

‘The discovery of ferroelectricity opens new pathways to novel classes of bioelectronic logic and memory devices, where polarization switching is used to record and retrieve information in the form of ferroelectric domains,’ said coauthor and senior scientist at ORNL’s Center for Nanophase Materials Sciences (CNMS) Sergei Kalinin.”

See the full post here.

From Oak Ridge Lab: “Computer Scientists Collect Computing Tools for Next-Generation Machines”

Oak Ridge National laboratory

Tools developers attempt to make change to hybrid architectures a smooth transition

“Researchers using the OLCF‘s [Oak Ridge Leadership Computing Facility] resources can foresee substantial changes in their scientific application code development in the near future.

The OLCF’s new supercomputer, a Cray XK6 named Titan with an expected peak speed of 10-20 petaflops (10-20 thousand trillion calculations per second), will use a hybrid architecture of conventional, multipurpose central processing units (CPUs) and highperformance graphics processing units (GPUs) which, until recently, primarily drove modern video game graphics. Titan is set to be operational by early 2013. The machine will supplant the OLCF’s current fastest supercomputer, Jaguar, a Cray XT5 using an entirely CPU-based platform.

With Titan’s arrival, fundamental changes to computer architectures will challenge researchers from every scientific discipline. Members of the OLCF’s Application Performance Tools (APT) group understand the challenge. Their goal is to make the transition as smooth as possible.

‘The effort necessary to glean insight from large-scale computation is already considerable for scientists,’ computational astrophysicist Bronson Messer said. ‘Anything that tool developers can do to reduce the burden of porting codes to new architectures, while ensuring performance and correctness, allows us to spend more time obtaining scientific results from simulations.’”

See the full article here.

From Oak Ridge Lab: “ORNL microscopy explores nanowires’ weakest link”

“Individual atoms can make or break electronic properties in one of the world’s smallest known conductors—quantum nanowires. Microscopic analysis at the Department of Energy’s Oak Ridge National Laboratory is delivering a rare glimpse into how the atomic structure of the conducting nanowires affects their electronic behavior.

The ORNL team’s microscopy confirmed that deliberately introduced defects, which are only the size of a single atom, could turn a conducting nanowire into an insulator by shutting down the path of electrons. Led by ORNL’s An-Ping Li, the research team used multiple-probe scanning tunneling microscopy to analyze nanowires made of a material called gadolinium silicide. ‘This type of one-dimensional conductor is expected to be a fundamental component in all quantum electronic architectures,’ said Li, a research scientist at ORNL’s Center for Nanophase Materials Science. ‘One advantage of GdSi2 nanowires is they are compatible with conventional silicon technology and are thus easier to implement in nanoelectronic devices.’”

A one-dimensional quantum nanowire (seen in yellow on left) can turn from a conductor to an insulator with the addition of a single atomic defect, according to microscopic analysis from Oak Ridge National Laboratory. Bundles of nanowires (right) are generally more stable, leading to better conductance. Image credit: An-Ping Li and Shengyong Qin

See the full post here.

ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.