Entries with tag sandia national laboratories.

Study: Mechanical Force Is More Effective than Chemicals in Fabricating Nanostructures

Simple pressure is more effective than existing chemical approaches in precisely forming nanoparticle arrays, according to new research headed by scientists from the US Department of Energy’s Sandia National Laboratories. “This is a foundational method that should enable [use of the arrays in the development of] a variety of devices, including flexible electronics such as antennas, chemical sensors and strain detectors,” said Sandia researcher Paul Clem, who helped lead the study. He said the approach could also help create transparent electrodes for solar cells or organic LEDs, which are frequently used in device displays. The newly patented technique uses two diamond plates to apply pressure, much like embossing, on a substrate. The researchers used nanoparticulate thin films with silver nanospheres but say the method would work with other gold, platinum, and other metal nanoparticles. They say their approach could easily be added to existing manufacturing processes. It also eliminates the waste-disposal and other challenges associated with using chemicals in forming nanoparticle arrays. The researchers published their work in the journal Nature Communications. (EurekAlert)(DOE/Sandia National Laboratories)(Nature Communications)

New Supercomputing Benchmark Planned

The benchmark used to test and rank supercomputer performance is outdated, prompting the creation of a new metric that will be used starting in November. Jack Dongarra, distinguished professor of computer science at the University of Tennessee and one of the compilers of the Top500 list of the world’s fastest supercomputers, says the Linpack benchmark, used for the past 20 years, is no longer a useful measurement of application performance. It measures linear equation calculations, while calculations with more complexity are now common. The latest iteration of the test was developed in 2008. It also means that those vendors constructing systems are building them to perform well on an outdated test rather than to perform current applications well. The new test, the High Performance Conjugate Gradient, uses complex calculations found in contemporary applications that require high bandwidth and low latency and that access data using irregular patterns. Dongarra developed the new test with Michael Heroux from Sandia National Laboratories at the request of the US Department of Energy, which was concerned about applying Linpack to exascale computer systems. The new test will be gradually adopted and will initially be used with Linpack. The new test will be introduced at the SC13 supercomputing conference in Denver this November, which is also when the next The Top500 list will be released. Tianhe-2, China’s National University of Defense Technology supercomputer, is currently the top-ranked system. (Computerworld)(ZDNet)(Inside HPC)(“Toward a New Metric for Ranking High Performance Computing Systems,” @ Sandia National Laboratories)

Fluidic Movement on Nanowires Trumps Tubes

The possibility that nanowires could naturally draw a liquid up their length has been theorized. Now, though, a team of researchers has shown that nanometer wires inserted into a pool of liquid naturally move the fluid along their surface. By contrast, tubes need suction to begin transporting fluids. The findings “might pave the way for new kinds of microelectromechanical systems to carry out research on materials at a molecular level.” Too, such small-scale fluid transport technology could benefit microfluidic devices such as a lab on a chip, biomedical research, or inkjet printers. The researchers, led by MIT scientists, used a special liquid and an electron microscope to observe the phenomenon. They say that the gravity-defying effect works with most liquids, including water, and could also be enhanced by applying an electric current to the wire to increase the force. The experiments were conducted with nanowires made of silicon, zinc oxide, tin oxide, and 2D graphene. They will also be using this research to further study different solid-liquid interactions, such as those that occur in electrodeposition and in the operation of batteries. Researchers from the US Sandia National Laboratories, the University of Pennsylvania, the University of Pittsburgh, and Zhejiang University contributed to the work, which appeared in the journal Nature Nanotechnology. (EurekAlert)(MIT News Office)

US National Lab Models Rocket Propellant Fires

A new US presidential directive has required Sandia National Laboratories researchers to use computer modeling to conduct a predictive, public-risk analysis of accidental fires that might occur during the launch of NASA space missions carrying radioactive materials. They say they analysis will combine experimental test data with multiphysics, high-fidelity models, an approach not previously attempted. The researchers are building an interface that will let them update, add different predictive features to, and validate their overall model. They are now evaluating the Rocstar software code that University of Illinois scientists developed and that may help with the modeling. (PhysOrg)(Sandia National Laboratories)

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