High-performance simulation, neutrons uncover three classes of protein motion

ScienceDaily (Oct. 2, 2011) — Molecular motion in proteins comes in three distinct classes, according to a collaboration by researchers at the Department of Energy's Oak Ridge National Laboratory and the University of Tennessee, in research reported in Physical Review Letters.

The research team, directed by ORNL-UT Governor's Chairs Jeremy Smith and Alexei Sokolov, combined high-performance computer simulation with neutron scattering experiments to understand atomic-level motions that underpin the operations of proteins.

"The analysis and interpretation of neutron scattering spectra are always difficult for complex molecules such as proteins," said Smith, who directs ORNL's Center for Molecular Biophysics. "We've performed experiments and then shown that simulation can provide a clear view of them. It allows us to see through the complexity and find out what motions are going on."

Defining the motions present -- localized diffusion, methyl group rotations and jumps -- is important as it allows scientists to think about how the motions determine the functions of proteins that are critical to all life.

"First, we found that experiment and simulation agreed perfectly with each other, which is remarkable," Smith said. "Second, the simulations told us that this type of neutron scattering can be interpreted in a very simple way."

Although the team performed its research on a particular protein called lysozyme, a natural antibacterial enzyme found in tears, saliva and egg whites, the researchers anticipate the technique will have a much broader impact in the neutron scattering community, aiding research in areas such as biofuel design or environmental remediation.

The combined simulation and neutron scattering approach should also be of use in the characterization of non-biological materials such as polymers. Smith notes that approximately half the neutron scattering experiments at ORNL's Spallation Neutron Source involve the study of motions in materials.

"These methods are of general applicability," Smith said. "Many experimentalists can now come to the ORNL's Spallation Neutron Source, measure a spectrum of whatever sample they have, and then apply this analysis in terms of three classes of motion to interpret their results."

The research was primarily conducted by ORNL's Liang Hong, with the support of Benjamin Lindner and Nikolai Smolin from ORNL. They performed neutron scattering experiments at ORNL's Spallation Neutron Source on the BASIS instrument and at the National Institute of Standards and Technology Center for Neutron Research.

The simulation component of the work was supported by ORNL's Laboratory Directed Research and Development program, while the neutron scattering component was supported by an Experimental Program to Stimulate Competitive Research (EPSCOR) grant to the University of Tennessee from the DOE Office of Science.

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

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by DOE/Oak Ridge National Laboratory.

Journal Reference:

Liang Hong, Nikolai Smolin, Benjamin Lindner, Alexei P. Sokolov, Jeremy C. Smith. Three classes of motion in the dynamic neutron-scattering susceptibility of a globular protein. Physical Review Letters, 2011; (accepted)

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

High-performance simulation, neutrons uncover three classes of protein motion

ScienceDaily (Oct. 2, 2011) — Molecular motion in proteins comes in three distinct classes, according to a collaboration by researchers at the Department of Energy's Oak Ridge National Laboratory and the University of Tennessee, in research reported in Physical Review Letters.

The research team, directed by ORNL-UT Governor's Chairs Jeremy Smith and Alexei Sokolov, combined high-performance computer simulation with neutron scattering experiments to understand atomic-level motions that underpin the operations of proteins.

"The analysis and interpretation of neutron scattering spectra are always difficult for complex molecules such as proteins," said Smith, who directs ORNL's Center for Molecular Biophysics. "We've performed experiments and then shown that simulation can provide a clear view of them. It allows us to see through the complexity and find out what motions are going on."

Defining the motions present -- localized diffusion, methyl group rotations and jumps -- is important as it allows scientists to think about how the motions determine the functions of proteins that are critical to all life.

"First, we found that experiment and simulation agreed perfectly with each other, which is remarkable," Smith said. "Second, the simulations told us that this type of neutron scattering can be interpreted in a very simple way."

Although the team performed its research on a particular protein called lysozyme, a natural antibacterial enzyme found in tears, saliva and egg whites, the researchers anticipate the technique will have a much broader impact in the neutron scattering community, aiding research in areas such as biofuel design or environmental remediation.

The combined simulation and neutron scattering approach should also be of use in the characterization of non-biological materials such as polymers. Smith notes that approximately half the neutron scattering experiments at ORNL's Spallation Neutron Source involve the study of motions in materials.

"These methods are of general applicability," Smith said. "Many experimentalists can now come to the ORNL's Spallation Neutron Source, measure a spectrum of whatever sample they have, and then apply this analysis in terms of three classes of motion to interpret their results."

The research was primarily conducted by ORNL's Liang Hong, with the support of Benjamin Lindner and Nikolai Smolin from ORNL. They performed neutron scattering experiments at ORNL's Spallation Neutron Source on the BASIS instrument and at the National Institute of Standards and Technology Center for Neutron Research.

The simulation component of the work was supported by ORNL's Laboratory Directed Research and Development program, while the neutron scattering component was supported by an Experimental Program to Stimulate Competitive Research (EPSCOR) grant to the University of Tennessee from the DOE Office of Science.

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

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by DOE/Oak Ridge National Laboratory.

Journal Reference:

Liang Hong, Nikolai Smolin, Benjamin Lindner, Alexei P. Sokolov, Jeremy C. Smith. Three classes of motion in the dynamic neutron-scattering susceptibility of a globular protein. Physical Review Letters, 2011; (accepted)

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Single-crystal arrays of graphene: Advance in efforts to develop a replacement for silicon in high-performance electronics

ScienceDaily (June 2, 2011) — University of Houston researchers have developed a method for creating single-crystal arrays of the material graphene, an advance that opens the possibility of a replacement for silicon in high-performance computers and electronics.

The work by UH researchers and their collaborators is featured on the cover of the June issue of Nature Materials.

Graphene is a one-atom-thick layer of carbon that was first fabricated in 2004. Single-crystal arrays of the material could be used to create a new class of high-speed transistors and integrated circuits that use less energy than silicon electronics because graphene conducts electricity with little resistance or heat generation.

But the industry needs a reliable and defect-free method for manufacturing large quantities of single crystals of graphene. The development reported in Nature Materials marks a step towards perfecting such a method.

"Using these seeds, we can grow an ordered array of thousands or millions of single crystals of graphene," said Qingkai Yu, the paper's first author. Yu developed the single-crystal growth process at the UH Center for Advanced Materials (CAM), where he was a research assistant professor of electrical and computer engineering.

"We hope the industry will look at these findings and consider the ordered arrays as a possible means of fabricating electronic devices," said Yu, who is now an assistant professor at Texas State University in San Marcos and remains a project leader at CAM.

Yu and Steven Pei, UH professor of electrical and computer engineering and CAM's deputy director, invented the graphene seeded-growth technique that UH patented in 2010.

"There is still a long way to go. However, this development makes the fabrication of integrated circuits with graphene transistors possible. This may actually be the first viable integrated circuit technology based on nano-electronics," Pei said.

Yong P. Chen, an assistant professor of nanoscience and physics at Purdue University, was the paper's co-corresponding author.

At CAM, single-crystal graphene arrays were grown on top of a copper foil inside a chamber containing methane gas using a process called chemical vapor deposition. This process was pioneered by Yu at CAM in 2008 and is now widely accepted as the standard method to create large-area graphene films for potential applications in touch-screen displays, e-books and solar cells.

"Graphene isn't there yet, in terms of high quality mass production like silicon, but this is a very important step in that direction," said Chen, who led the graphene characterization efforts at Purdue.

In addition to Yu and Pei, UH graduate students Wei Wu and Zhihua Su, postdoctoral researchers Zhihong Liu and Peng Peng and assistant professor Jiming Bao along with Chen and nine other researchers from Purdue University, Brookhaven National Laboratory, Argonne National Laboratories and Carl Zeiss SMT Inc. co-authored the paper.

Last year, two scientists received the Nobel Prize in physics for discovering graphene. At that time, Yu was working at CAM to develop ways to produce mass quantities of high-quality graphene.

The findings reported in Nature Materials demonstrated that researchers could control the growth of the ordered arrays. The researchers also were the first to demonstrate the electronic properties of individual grain boundaries.

The research was supported through a variety of funding sources, including the National Science Foundation, the U.S. Department of Energy, the Department of Homeland Security, the Defense Threat Reduction Agency, IBM Inc., the Welch Foundation, the Miller Family Endowment and Midwest Institute for Nanoelectronics Discovery.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Houston.

Journal Reference:

Qingkai Yu, Luis A. Jauregui, Wei Wu, Robert Colby, Jifa Tian, Zhihua Su, Helin Cao, Zhihong Liu, Deepak Pandey, Dongguang Wei, Ting Fung Chung, Peng Peng, Nathan P. Guisinger, Eric A. Stach, Jiming Bao, Shin-Shem Pei, Yong P. Chen. Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition. Nature Materials, 2011; 10 (6): 443 DOI: 10.1038/nmat3010

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Single-crystal arrays of graphene: Advance in efforts to develop a replacement for silicon in high-performance electronics

ScienceDaily (June 2, 2011) — University of Houston researchers have developed a method for creating single-crystal arrays of the material graphene, an advance that opens the possibility of a replacement for silicon in high-performance computers and electronics.

The work by UH researchers and their collaborators is featured on the cover of the June issue of Nature Materials.

Graphene is a one-atom-thick layer of carbon that was first fabricated in 2004. Single-crystal arrays of the material could be used to create a new class of high-speed transistors and integrated circuits that use less energy than silicon electronics because graphene conducts electricity with little resistance or heat generation.

But the industry needs a reliable and defect-free method for manufacturing large quantities of single crystals of graphene. The development reported in Nature Materials marks a step towards perfecting such a method.

"Using these seeds, we can grow an ordered array of thousands or millions of single crystals of graphene," said Qingkai Yu, the paper's first author. Yu developed the single-crystal growth process at the UH Center for Advanced Materials (CAM), where he was a research assistant professor of electrical and computer engineering.

"We hope the industry will look at these findings and consider the ordered arrays as a possible means of fabricating electronic devices," said Yu, who is now an assistant professor at Texas State University in San Marcos and remains a project leader at CAM.

Yu and Steven Pei, UH professor of electrical and computer engineering and CAM's deputy director, invented the graphene seeded-growth technique that UH patented in 2010.

"There is still a long way to go. However, this development makes the fabrication of integrated circuits with graphene transistors possible. This may actually be the first viable integrated circuit technology based on nano-electronics," Pei said.

Yong P. Chen, an assistant professor of nanoscience and physics at Purdue University, was the paper's co-corresponding author.

At CAM, single-crystal graphene arrays were grown on top of a copper foil inside a chamber containing methane gas using a process called chemical vapor deposition. This process was pioneered by Yu at CAM in 2008 and is now widely accepted as the standard method to create large-area graphene films for potential applications in touch-screen displays, e-books and solar cells.

"Graphene isn't there yet, in terms of high quality mass production like silicon, but this is a very important step in that direction," said Chen, who led the graphene characterization efforts at Purdue.

In addition to Yu and Pei, UH graduate students Wei Wu and Zhihua Su, postdoctoral researchers Zhihong Liu and Peng Peng and assistant professor Jiming Bao along with Chen and nine other researchers from Purdue University, Brookhaven National Laboratory, Argonne National Laboratories and Carl Zeiss SMT Inc. co-authored the paper.

Last year, two scientists received the Nobel Prize in physics for discovering graphene. At that time, Yu was working at CAM to develop ways to produce mass quantities of high-quality graphene.

The findings reported in Nature Materials demonstrated that researchers could control the growth of the ordered arrays. The researchers also were the first to demonstrate the electronic properties of individual grain boundaries.

The research was supported through a variety of funding sources, including the National Science Foundation, the U.S. Department of Energy, the Department of Homeland Security, the Defense Threat Reduction Agency, IBM Inc., the Welch Foundation, the Miller Family Endowment and Midwest Institute for Nanoelectronics Discovery.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Houston.

Journal Reference:

Qingkai Yu, Luis A. Jauregui, Wei Wu, Robert Colby, Jifa Tian, Zhihua Su, Helin Cao, Zhihong Liu, Deepak Pandey, Dongguang Wei, Ting Fung Chung, Peng Peng, Nathan P. Guisinger, Eric A. Stach, Jiming Bao, Shin-Shem Pei, Yong P. Chen. Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition. Nature Materials, 2011; 10 (6): 443 DOI: 10.1038/nmat3010

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here