Published on March 11th, 2014 | By: Eileen De Guire0
Other materials stories that may be of interestPublished on March 11th, 2014 | By: Eileen De Guire
Sandia National Laboratory researchers harness magnetic fields for challenging heat transfer problems. Credit: Sandia; YouTube.
Sandia National Laboratories researchers Jim Martin and Kyle Solis have discovered how to harness magnetic fields to create vigorous, organized fluid flows in particle suspensions. The magnetically stimulated flows offer an alternative when heat transfer is difficult because they overcome natural convection limits. Martin and Solis even demonstrated a heat transfer valve that could potentially control the temperature of computer processors. The pair’s research, funded by the Department of Energy’s Office of Science, is concentrating on extending fundamental understanding of novel heat transport in liquids, evaluating the effectiveness of various flows and exploring what happens when researchers modify experimental parameters. Martin and Solis found the patterns occur only for magnetic particles shaped like plates, essentially magnetic confetti. Spherical and rod-like particles do not produce the effects.
University of Washington scientists have built the thinnest-known LED that can be used as a source of light energy in electronics. The LED is based off of two-dimensional, flexible semiconductors, making it possible to stack or use in much smaller and more diverse applications than current technology allows. The UW’s LED is made from flat sheets of the molecular semiconductor tungsten diselenide, a member of a group of two-dimensional materials that have been recently identified as the thinnest-known semiconductors. Researchers used regular adhesive tape to extract single sheets of the material from thick, layered pieces. In addition to light-emitting applications, this technology could open doors for using light as interconnects to run nanoscale computer chips instead of standard devices that operate off the movement of electrons, or electricity.
Using an artificial protein that contains metal, researchers were able to inhibit the growth of a pathogenic bacterium prevalent in hospitals which cause diseases to humans and has a high resistance to antibiotics. The inhibition of growth has been achieved through the deprivation of iron uptake using an artificial metalloprotein. P. aeruginosa bacteria exists in many aquatic areas and is prevalent in hospitals. Although they do not usually affect healthy people, they increase the risk for infection of patients with low immunity. Their high resistance towards many antibiotics makes complete elimination of them extremely difficult. Like humans, bacteria require the uptake of heme iron for their survival, and a protein (HasA) is secreted from bacteria to capture heme from its host. The heme-bound HasA protein transfers heme via receptor proteins on the cell surface of the bacterium, P. aeruginosa.
(Materials Views) Two important processing steps for numerous biotechnological and chemical process routes are filtration and extraction. Both require adsorbents with well-defined properties. Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. They feature high specific surface areas, but the pore sizes are just a few nanometers. Thus, their application in filtration is limited to gases and small molecules. Ceramic foams on the other hand show high open porosity with tunable pore sizes. However, they exhibit often low specific surface areas, which are disadvantageous for the adsorbents’ efficiency. Uniform particles so called microbeads and microbead-derived monolithic adsorbents (MAds) combine both advantages of zeolites and ceramic foams. A group of scientists at the University Bremen, Germany successfully prepared silica/alumina microbeads with good specific surface area and porosity. In a new study, they applied an easy, inexpensive, and versatile rapid sintering technique using a tube furnace.
A team of researchers working at the University of Notre Dame has discovered a whole new group of quasicrystals. In their paper published in the journal Nature, the team describes how they accidently created a new kind of quasicrystal as part of a series of experiments designed to learn more about electron distribution in ferrocenecarboxylic acids. In this latest discovery, the quasicrystals self-formed after the researchers placed a layer of iron containing molecules of ferrocenecarboxylic acid on top of a gold surface. The team was expecting to see a linear group of stable molecules pairing up as dimers, but instead were surprised to find that they had formed into five sided rosettes—it was the rosettes that pushed other molecules into bonding forming crystalline shapes, resulting in the formation of 2D quasicrystals that took the form of several different shapes: stars, boats, pentagons, rhombi, etc., all repeated in haphazard fashion. In studying the quasicrystals using scanning tunnelling microscopy, the researchers found that they were held together by weak hydrogen bonds rather that the strong ionic bonds found in other such molecules.
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