From the Department of Energy’s Oak Ridge National Laboratory
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Ecology—Better mercury predictions
Analyses of creek algae informed a new model that can more accurately predict the presence of the neurotoxin methylmercury in small headwater ecosystems. For about two years, Oak Ridge National Laboratory scientists studied biofilms collected during different seasons and from various locations along an East Tennessee creek bed and discovered methylmercury in tiny oxygen-deficient pockets within the biofilms’ complex ecosystem. “For methylmercury to be produced, the samples had to be grown and incubated in the light to actively photosynthesize, which means oxygen is present,” said ORNL’s Scott Brooks. “However, methylmercury only forms in anaerobic, or oxygen-free, zones, which means there are optimal conditions for methylmercury production at small scales within the biofilms.” The team also found that simply shaking the samples disrupted the biofilms’ delicate ecosystem and reduced methylmercury levels. Their newly developed model, described in Environmental Science & Technology, could be applied to other water systems to predict methylmercury production. [Contact: Sara Shoemaker, (865) 576-9219; firstname.lastname@example.org]
Caption: Over time, algae biofilms accumulated on glass washers affixed to a plastic pegboard submerged in East Fork Poplar Creek in Oak Ridge, Tenn. ORNL researchers further analyzed the samples in the laboratory to determine the production of methylmercury. Credit: Todd Olsen and Scott Brooks/Oak Ridge National Laboratory, U.S. Dept. of Energy
Gasoline-powered automobiles could achieve an 8 percent or greater fuel efficiency gain through a new combustion strategy developed at Oak Ridge National Laboratory. Scientists have demonstrated a new method for reforming fuel over a catalyst, a process that chemically converts fuel into a hydrogen-rich blend. This blend allows more work to be extracted from the engine cylinders, increasing efficiency and saving fuel. “Typically, you incur a fuel penalty when reforming fuel,” said ORNL’s Jim Szybist. “We’ve created a systematic approach that addresses that issue and can be used with conventional fuels and conventional emissions controls.” The team published the method in Energy & Fuels and is working at ORNL’s National Transportation Research Center to demonstrate similar fuel savings at a wider range of engine operation. [Contact: Kim Askey, (865) 576-2841; email@example.com]
Caption: ORNL’s Jim Szybist works with a multi-cylinder engine at the lab’s National Transportation Research Center. Credit: Jason Richards/Oak Ridge National Laboratory, U.S. Dept. of Energy
Oak Ridge National Laboratory researchers have directly written high-purity metallic structures narrower than a cold virus—which could open nanofabrication opportunities in electronics, drug delivery, catalysis and chemical separations. At ORNL’s Center for Nanophase Materials Sciences, the team rastered a beam from a helium-ion microscope through a solution to locally deposit platinum, forming a ribbon only 15 nanometers in diameter. “This is the first occurrence of direct-write nanofabrication from a liquid-phase precursor using an ion microscope,” said ORNL’s Olga Ovchinnokova. “With full understanding from experiment and theory, we direct-wrote precise structures with highly pure material using unique tools.” The team ran calculations on ORNL’s Titan supercomputer and analyzed data from experiments and simulations to understand the dynamic interactions among ions, solids and liquids essential for optimizing the process. Their results were published in the journal Nanoscale. [Contact: Dawn Levy, (865) 576-6448; firstname.lastname@example.org]
Caption #1: ORNL researchers married helium-ion microscopy with a liquid cell from North Carolina-based Protochips Inc., to fabricate exceedingly pure, precise platinum structures. Credit: Stephen Jesse/Oak Ridge National Laboratory, U.S. Dept. of Energy
Caption #2: These structures can be made less than 15 nanometers wide (the white scale bar is 50 nanometers) and are more precise than any produced by direct-write technology. Credit: Stephen Jesse/Oak Ridge National Laboratory, U.S. Dept. of Energy
New insights into certain catalytic enzymes formed by bacteria to break down antibiotics may lead to the design of drugs better equipped to combat resistant bacteria. Scientists at Oak Ridge National Laboratory used neutron crystallography at the lab’s Spallation Neutron Source to study the interaction between one of these enzymes, called a beta-lactamase, and an antibiotic, building on data collected with x-ray crystallography. “Antibiotics destroy bacteria by preventing cell walls from forming, but beta-lactamases bind to the drugs to stop this attack,” said ORNL’s Patricia Langan, coauthor of a study published in ACS Catalysis. The binding of the antibiotic subtly altered the protein structure in the beta-lactamase and helped transfer a proton from one part of the enzyme to another, the first step toward blocking the drug’s effects. “With neutrons, we can gain a much deeper understanding of the mechanisms that break down antibiotics,” Langan added. [Contact: Kelley Smith, (865) 576-5668; email@example.com]
Caption: Using neutrons, an ORNL research team studied the protein structure of bacteria-produced enzymes called beta-lactamases by examining one of them to better understand how resistant bacteria behave. This research could help inform the development of more effective antibiotics. Credit: Leighton Coates/Oak Ridge National Laboratory, U.S. Dept. of Energy.
Nuclear scientists at Oak Ridge National Laboratory are retooling existing software used to simulate radiation transport in small modular reactors, or SMRs, to run more efficiently on next-generation supercomputers. ORNL is working on various aspects of advanced SMR designs through simulations currently performed on the lab’s Titan supercomputer. “The next generation of supercomputers will run on more sophisticated architectures based predominately on graphics processing units, or GPUs,” ORNL’s Steven Hamilton said. “For the radiation transport algorithms to be compatible, we are preparing now so that we can take advantage of the full capability of GPU-based systems and run simulations as efficiently as possible.” The ORNL team leveraged Titan’s hybrid platform system that includes GPUs to develop and test the radiation transport codes. The newly developed method, described in Annals of Nuclear Energy, will be further scaled up to run larger simulations efficiently when future machines come online. [Contact: Sara Shoemaker, (865) 576-9219; firstname.lastname@example.org]
Caption: ORNL uses supercomputers to simulate radiation transport in small modular reactors using Monte Carlo codes. Credit: Steven Hamilton/Oak Ridge National Laboratory, U.S. Dept. of Energy