Science

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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.

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From Mars Rover: Panorama Above 'Perseverance Valley'

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This June 2017 view from the Pancam on NASA's Opportunity Mars rover shows the area just above "Perseverance Valley" on a large crater's rim. A broad notch in the crest of the rim, at right, might have been a spillway for a fluid that carved the valley, out of sight on the other side of the rim.

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The first light atomic nucleus with a second face

To some degree of approximation, atomic nuclei look like spheres which in most cases are distorted to a greater or lesser extent. When the nucleus is excited, its shape may change, but only for an extremely brief moment, after which it returns to its original state. A relatively permanent 'second faceâ' of atomic nuclei has so far only been observed in the most massive elements. In a spectacular experiment, physicists from Poland, Italy, Japan, Belgium and Romania have for the first time succeeded in registering it in a nucleus recognized as being light.

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In an experiment performed at the Romanian accelerator centre IFIN-HH, an international team of physicists observed a 'second face' of the nickel-66 nuclei: a relatively stable excited state in which the shape of nucleus is changed.

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Here's a tip: Indented cement shows unique properties: Rice University models reveal nanoindentation can benefit crystals in concrete

Rice University scientists have determined that no matter how large or small a piece of tobermorite is, it will respond to loading forces in precisely the same way. But poking it with a sharp point will change its strength.

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Indented tobermorite, a natural analog to the calcium-silicate-hydrate mix in cement, responds differently than bulk tobermorite, depending on the size of the indentation and the force. Layers that bond through indentation remain that way after the force is removed, according to Rice University engineers.

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Semiliquid chains pulled out of a sea of microparticles

An electrode brought to the surface of a liquid that contains microparticles can be used to pull out surprisingly long chains of particles. Curiously enough, the particles in the chains are held together by a thin layer of liquid that covers them.

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This is a chain of microparticles pulled out of the liquid by an electrode.