Science

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From hot to cold: How to move objects at the nanoscale: Moving a single gold nanocluster on a graphene membrane, thanks to a thermal gradient applied to the borders: a new study sheds light on the physical mechanisms driving this phenomenon

To move a nanoparticle on the surface of a graphene sheet, you won't need a "nano-arm": by applying a temperature difference at the ends of the membrane, the nanocluster laying on it will drift from the hot region to the cold one. In addition, contrary to the laws ruling the world at the macroscale, the force acting on the particle -- the so-called thermophoretic force -- should not decrease as the sheet length rises, sporting a so-called ballistic behavior, same as a bullet in a gun barrel. In fact, simulations show that vertical thermal oscillations of the graphene membrane flow ballistically from hot to cold, providing a push to the object. Yet, these vertical waves, known as flexural phonons, should not be able to impress any lateral shift to an object. Nevertheless, computer simulations show that they do push the nanocluster in the same way a surfboard is taken to shore by ocean waves. And, of course within limits, no matter how far away the wave came from. These theoretical predictions could be of great interest in the frame of manipulating materials at the nanoscale, in view of potential technological applications.

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The theoretical predictions of these study could be of great interest in the frame of manipulating materials at the nanoscale for technological applications.

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2-faced 2-D material is a first at Rice: Rice University materials scientists create flat sandwich of sulfur, molybdenum and selenium

Like a sandwich with wheat on the bottom and rye on the top, Rice University scientists have cooked up a tasty new twist on two-dimensional materials.

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Rice University materials scientists replace all the atoms on top of a three-layer, two-dimensional crystal to make a transition-metal dichalcogenide with sulfur, molybdenum and selenium.

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Five Berkeley Lab Researchers Receive DOE Early Career Research Awards

Five scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) have been selected by the U.S. Department of Energy’s (DOE’s) Office of Science to receive significant funding for research through its Early Career Research Program.

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NASA's Voyager Spacecraft Still Reaching for the Stars After 40 Years

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An artist concept depicting one of the twin Voyager spacecraft. Humanity's farthest and longest-lived spacecraft are celebrating 40 years in August and September 2017.

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High-speed FM-AFM and simulation reveal atomistic dissolution processes of calcite in water

Calcite is one of the most abundant components of the Earth crust, the outer-most layer of the Earth, constituting as the largest carbon reservoir in the global carbon cycle in nature. Thus, large-scale dissolution of calcite would give an enormous impact on the weather, geography, aquatic environment and so on; more specifically, for example, changes in the carbon dioxide concentration of the air and the acidity of the ocean. Recently, the dissolution mechamism of calcite attracts much attention because of its importance in geologic carbon sequestration (GCS) technology to capture carbon dioxide from the air and to store it underground. In order to precisely predict such a large-scale and long-term phenomenon, the dissolution mechanism of calcite should be understood at an atomic level in a precise manner.

(a) Atomistic model of calcite surface. (b) The dissolution processes of calcite surface in water observed with high-speed FM-AFM. It is observed that the step is moving from lower-right to upper-left. Along the step is also seen the transition region. (c) Averaged height profile measured along the line PQ indicated in (b). The height of a monolayer step is ~0.3 nm, but that of the transition region is smaller. A terrace described in the Figure indicates a flat area at the atomic level on the crystal surface. The upper terrace is higher by one monolayer of CaCO3 than the lower terrace.

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Scientists discover new magnet with nearly massless charge carriers

Advances in modern electronics has demanded the requisite hardware, transistors, to be smaller in each new iteration. Recent progress in nanotechnology has reduced the size of silicon transistors down to the order of 10 nanometers. However, for such small transistors, other physical effects set in, which limit their functionality. For example, the power consumption and heat production in these devices is creating significant problems for device design. Therefore, novel quantum materials and device concepts are required to develop a new generation of energy-saving information technology. The recent discoveries of topological materials -- a new class of relativistic quantum materials -- hold great promise for use in energy saving electronics.

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The magnetic and electronic states of newly discovered Sr1-yMn1-zSb2 are depicted by spheres representing the positions of the atoms in the crystal structure of this material with strontium (Sr) depicted by the small violet spheres; antimony (Sb) by the large blue spheres; and manganese (Mn) by the purple spheres. The arrows attached to the Mn atoms represent the magnetic moments of these atoms which align in the orientation shown to give the magnetic properties of Sr1-yMn1-zSb2. Also depicted are the energy and momentum states of the conducting electrons, or charge carriers, which have a Dirac-like dispersion relation shown in gold.

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NASA Solves a Drizzle Riddle

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Drizzle over land.

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Eclipse Balloons to Study Effect of Mars-Like Environment on Life

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This picture of Montana was taken from the stratosphere (84,000 feet or 25,000 meters) during one of Montana Space Grant Consortium's high-altitude balloon tests on April 19, 2014.

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Physicists gain new insights into nanosystems with spherical confinement: Enormous potential for the targeted delivery of pharmaceutical agents and the creation of tailored nanoparticles

Theoretical physicists led by Professor Kurt Binder and Dr. Arash Nikoubashman at Johannes Gutenberg University Mainz (JGU) in Germany have used computer simulations to study the arrangement of stiff polymers in spherical cavities. These confined systems play an important role for a wide range of applications, such as the fabrication of nanoparticles for targeted drug delivery and for tailored nanomaterials. Furthermore, the investigated systems can give crucial insights into the inner workings of biological problems where confinement effects are crucial, such as the packaging of double-stranded DNA in bacteriophage capsids and the self-assembly of actin filaments in cells.

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Bipolar structure assembled of stiff polymers at low densities.

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Rice U. scientists map ways forward for lithium-ion batteries for extreme environments: Paper details developments toward high-temperature batteries

Lithium-ion batteries are popular power sources for cellphones and other electronics, but problematic in extreme heat or cold. A Rice University laboratory has suggested ways to extend their range.

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A map created by materials scientists at Rice University will help labs develop lithium-ion batteries for extreme environments.