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From the Department of Energy’s Oak Ridge National Laboratory

September 2018

 

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Buildings—Inside out

 

Vacuum insulation technology called modified atmosphere insulation, or MAI, could be a viable solution for improving the energy performance of buildings, based on a study by Oak Ridge National Laboratory and industry partners. ORNL researchers used a specialized environmental chamber to characterize panels containing foam-encapsulated MAI cores and exposed them to outdoor weatherization tests via real building applications. Laboratory experiments verified the panels’ thermal resistance to heat flow to be at least twice that of current building insulation materials made of plastic foams, cellulose or fiberglass. “Buildings consume 40 percent of the nation’s energy and about 20 percent of the buildings’ portion is due to heat gains or losses through the building enclosure,” said ORNL’s Kaushik Biswas, lead coauthor of the study. “We’ve proven that MAI-based composites are technically viable options for buildings providing higher performance than current insulations.” The team’s results were published in the journal Applied Energy. [Contact: Jennifer Burke, (865) 576-3212; burkejj@ornl.gov]

 

Image 1: https://www.ornl.gov/sites/default/files/Buildings-Inside_out2.jpg

 

Caption: ORNL researcher Kaushik Biswas analyzes the thermal performance of a two-by-two foot composite panel covered with smaller MAI panels separated by foam insulation. Credit: Jason Richards/Oak Ridge National Laboratory, U.S. Dept. of Energy

 

Image 2: https://www.ornl.gov/sites/default/files/Buildings-Inside_out.jpg

 

Caption: An infrared image shows polysio foam only and foam-encapsulated MAI core sections, in yellow and orange respectively. The orange areas indicate lower heat transfer because of the higher thermal resistance of the MAI sections. Credit: Oak Ridge National Laboratory, U.S. Dept. of Energy

 

Computing—Quantum in any language

 

Computer scientists at Oak Ridge National Laboratory have developed an open source software platform that allows quantum programs to run on multiple quantum computers regardless of their unique architecture. Quantum computers promise to revolutionize modern computing. Their systems are based on quantum physics, where each quantum bit, or qubit, represents both a 1 and a 0 at the same time. “Several companies have developed quantum computers, and each has associated software that users must learn in order to execute programs,” said Alex McCaskey of ORNL’s Quantum Computing Institute. “To enable application portability, we have created a heterogeneous programming model called XACC that allows quantum acceleration within standard or high-performance computing software workflows in a quantum language and hardware independent manner.” ORNL scientists leveraged XACC as part of the first successful simulation of an atomic nucleus using a quantum computer. Details of the XACC programming model were published in SoftwareX. [Contact: Sara Shoemaker, (865) 576-9219; shoemakerms@ornl.gov]

Image: https://www.ornl.gov/sites/default/files/deuteron.jpg

 

Caption: ORNL scientists leveraged XACC software as part of the first successful simulation of an atomic nucleus using a quantum computer. Credit: Andy Sproles/Oak Ridge National Laboratory, U.S. Dept. of Energy

 

Nanoscience—Directing atoms

 

An Oak Ridge National Laboratory-led team used a scanning transmission electron microscope to selectively position single atoms below a crystal’s surface for the first time. “We’re moving individual dopants where we want them to go,” said Bethany Hudak of ORNL. “Direct atom positioning represents one step toward realizing the single-atom devices potentially needed to build future quantum computers.” The researchers grew a crystal consisting of silicon atoms but containing a few bismuth atoms. The bismuth atoms’ larger size caused strain on the lattice framework of the crystal. Then, they developed a method to employ the microscope’s electron beam to selectively hit a column of silicon atoms with enough energy to eject one from its lattice position, enabling a bismuth atom to slide into the vacant spot. Next steps for the work, which was published in ACS Nano, include controlling atom placement at different crystal depths and programming the electron microscope to create specific shapes. [Contact: Dawn Levy, (865) 576-6448; levyd@ornl.gov]

 

Image 1: https://www.ornl.gov/sites/default/files/B_Hudak_ORNL.jpg

 

Caption: ORNL’s Bethany Hudak places a crystal sample in an aberration-corrected scanning transmission electron microscope. Her team was able to selectively position bismuth atoms in the bulk of a crystal  below its surface—a feat that has implications for constructing future quantum computers. Credit: Genevieve Martin/Oak Ridge National Laboratory, U.S. Dept. of Energy

 

Image 2: https://www.ornl.gov/sites/default/files/atoms_red_Hudak_ORNL.jpg

 

Caption: In this electron microscope image of bismuth atoms (circled) in a silicon crystal, white dotted circles indicate bismuth atoms that have been moved into positions to form an ordered array while green dotted circles show bismuth atoms that have yet to be moved to complete the array. The scale bar is one nanometer, or a billionth of a meter. Credit: Bethany Hudak/Oak Ridge National Laboratory, U.S. Dept. of Energy

 

Ecology—Unmasking mercury

 

Biologists from Oak Ridge National Laboratory and the Smithsonian Environmental Research Center have confirmed that microorganisms called methanogens, which are found in anaerobic environments such as soil, water and sewage, can transform mercury into the neurotoxin methylmercury with varying efficiency across species. Methylmercury can accumulate in fish, crops and water and potentially impact human health. Previously, bacteria that thrive on iron and sulfate were proven as producers of methylmercury along with a single methanogen. “With this confirmation that methylation is widespread in the methanogen community, we have shed light on the possible source of methylmercury in low-iron, low-sulfate ecosystems like rice paddies and permafrost landscapes,” said ORNL’s Dwayne Elias. “This is a critical step toward our larger goal of determining the factors that promote methylmercury production and finding ways to prevent or lessen its production in the environment.” The findings were published in mBio. [Contact: Kim Askey, (865) 576-2841; askeyka@ornl.gov]

 

Image 1: https://www.ornl.gov/sites/default/files/Methanogen_mercury_study3.jpg

 

Caption: Scientists examine methane gas bubbles produced by microbes living in the soil and groundwater in thawing permafrost landscapes. Credit: David Graham/Oak Ridge National Laboratory, U.S. Dept. of Energy

 

Image 2: https://www.ornl.gov/sites/default/files/Methanogen_mercury_study4.jpg

 

Caption: Methanogens could be a key source of methylmercury in permafrost landscapes such as this area under study through the DOE Next Generation Ecosystem Experiments-Arctic, or NGEE-Arctic, project. Credit: David Graham/Oak Ridge National Laboratory, U.S. Dept. of Energy

 

Nuclear—Advancing molten salt reactors

 

Experts focused on the future of nuclear technology will gather at Oak Ridge National Laboratory for the fourth annual Molten Salt Reactor Workshop on October 3–4. Stakeholders from all areas of the MSR community, including industry, academia, the Department of Energy and the Nuclear Regulatory Commission, will discuss topics around this year’s theme: Creating a Self-Sustaining Environment for MSR Success. “It is exciting to see how momentum is building,” said ORNL’s Lou Qualls, who expects more than 200 participants at this year’s event. “We view this workshop as a springboard for action, and this year is an opportunity to begin the steps needed to move MSRs to the grid.” The workshop is part of the first Nuclear Opportunities Week, which will include the Nuclear Suppliers Workshop at ORNL, the Millennial Nuclear Caucus at the Y-12 National Security Complex and a 75th anniversary of nuclear energy celebration. [Contact: Jason Ellis, (865) 241-5819; ellisjk@ornl.gov]

 

Image: https://www.ornl.gov/sites/default/files/MSR_design_legacy.jpg

 

Caption: ORNL’s legacy of nuclear innovation includes the 1960s Molten Salt Reactor Experiment, a project that continues to offer valuable insights to scientists studying the potential of molten salt reactor designs. Workers assemble the MSRE reactor core, which included 69 cubic feet of graphite formed into 513 graphite core blocks. Credit: U.S. Dept. of Energy