MATERIALS -- Next-generation electronics . . .
Changing the behavior of a material isn't big magic – it's nanoscale chemistry. Alejandro Lopez-Bezanilla used the computing power of Oak Ridge National Laboratory's Jaguar supercomputer, America's fastest, to study the effects of adding oxygen, sulfur and hydrogen to nanoribbons made of boron nitride. The added elements changed the behavior of boron nitride – a good insulator – into that of a metal. That makes the material promising for faster computer chips and smarter cell phones. Stable, inexpensive boron nitride can serve as a substrate to support blazing-fast graphene, a material being studied for next-generation electronics. Graphene and boron nitride can be created in 1-atom-thick sheets and cut into ribbons to carry electrons and their on/off electronic messages. [Written by Sandra Allen McLean; media contact: Ron Walli, (865) 576-0226; wallira@ornl.gov]
SUPERCOMPUTING -- Optimization tools . . .
An upgrade is transforming Oak Ridge National Laboratory's Jaguar supercomputer, America's fastest, into Titan, a next-generation supercomputer that will employ the latest AMD Opteron central processing units as well as NVIDIA Tesla graphics processing units — energy-efficient processors that accelerate specific types of calculations in scientific application codes. Titan's hybrid architecture will bring fundamental changes for researchers from academia, industry and government that employ computing resources. Members of the Oak Ridge Leadership Computing Facility's Application Performance Tools group are collaborating with Allinea, CAPS Enterprise, and the Technical University of Dresden to develop software tools to help with new challenges presented by Titan's design. [Written by Eric Gedenk; media contact: Ron Walli, (865) 576-0226; wallira@ornl.gov]
BIOFUELS -- Mega biomass . . .
Molecular-level studies of tension wood formation in poplars could ultimately fuel the discovery of biomass crops with thicker cell walls, less lignin and more cellulose that can be converted into ethanol. While typical poplar woody biomass is composed of about 45 percent cellulose, tension wood cell walls are composed of more than 90 percent cellulose. "If you increase the cellulose in your feedstock material, then you can potentially extract more sugars," said Udaya Kalluri of ORNL's Biosciences Division. From a functional perspective, tension wood enables trees to flex in the wind, but that secondary cell wall layer could also end up powering more flex fuel vehicles. Partners in this BioEnergy Science Center project are Georgia Tech and National Renewable Energy Laboratory. [Contact: Ron Walli, (865) 576-0226; wallira@ornl.gov]
BIOLOGY -- Tailoring toxicity of nanoparticles . . .
By selectively applying different coatings, scientists have discovered they can influence the toxicity of particles on mouse cell lines from the lung and immune system. These findings, published in Langmuir, build on previous work that showed surface coatings can influence toxicity to bacteria. "The coating can cause relatively higher toxicity or no toxicity to the strains of bacteria that were evaluated," said corresponding author Mitch Doktycz of Oak Ridge National Laboratory's Biosciences Division. This work is significant because it may be possible to tailor nanoparticle toxicity with simple coatings, and this may prove useful for treating infectious diseases. The paper also underscores the need for an improved fundamental understanding of nanoparticle characteristics and transformations that may occur in real environments. The paper is titled "Cytotoxicity Induced by Engineering Silver Nanocrystallites is Dependent on Surface Coatings and Cell Types." [Contact: Ron Walli, (865) 576-0226; wallira@ornl.gov]
NEUTRONS -- Analyzing the antibacterial assault . . .
A combination of advanced techniques at Oak Ridge National Laboratory helped researchers gain a better understanding of how some proteins attack bacteria. Colicins, a family of protein toxins, kill E. coli by crossing the bacterial membrane to exert their toxic effects. One family member, Colicin N, utilizes outer membrane protein F, or OmpF, to penetrate the bacterial membrane. Since neutron scattering alone cannot differentiate between the complex formed between Colicin N and OmpF in membranes, University of Newcastle scientists collaborated with Kevin Weiss in the Center for Structural Molecular Biology's Bio-Deuteration Laboratory to label OmpF with deuterium. This allowed the individual proteins to be selectively highlighted in neutron scattering experiments, a critical step in determining how colicins cross the membrane barrier. Results from these experiments support the hypothesis that Colicin N penetrates the E. coli membrane at the perimeter of OmpF and reveal possible new routes for antibiotics to enter bacteria. [Written by Emma Macmillan; media contact: Ron Walli, (865) 576-0226; wallira@ornl.gov]