Hot and Cold Water Seen Through a Thermal Im…

Hot and Cold Water Seen Through a Thermal Imaging Camera. Via FLIR Systems @flir 

Hydrogen made from seawater

materialsworld:

University of Houston Texas Center for Superconductivity Director, Zhifeng Ren. Image credit: University of Houston. 

A new catalyst has enabled hydrogen to be made from seawater. 

University of Houston, USA, researchers found combining an oxygen and a hydrogen evolution reaction catalyst together achieved current densities capable of supporting industrial demands while requiring relatively low voltage to start seawater electrolysis.

The researchers said the device, made with non-noble metal nitrides, avoids obstacles that have made it difficult to make hydrogen or safe drinking water from seawater. 

University of Houston Texas Center for Superconductivity Director, Zhifeng Ren, said a major issue had been that there wasn’t a catalyst that could split seawater to produce hydrogen without also setting free ions of sodium, chlorine, calcium and other components of seawater, which once freed can settle on the catalyst and render it inactive. Chlorine ions are especially challenging, in part because chlorine requires only a slightly higher voltage to free than is needed to free hydrogen.

The researchers designed and synthesised a 3D core-shell oxygen evolution reaction catalyst using transition metal-nitride, with nanoparticles made of a nickle-iron-nitride compound and nickle-molybdenum-nitride nanorods on porous nickle foam.

University of Houston Postdoctoral Researcher and first paper author, Luo Yu, said the new oxygen evolution reaction catalyst was paired with a hydrogen one of nickle-molybdenum-nitride nanorods.

The catalysts were integrated into a two-electrode alkaline electrolyser, which can be powered by waste heat via a thermoelectric device or by an AA battery.

Cell voltages required to produce a current density of 100 milliamperes per square centimetre (a measure of current density, or mA cm-2) ranged from 1.564V to 1.581V.

The voltage is significant, Yu said, because while a voltage of at least 1.23V is required to produce hydrogen, chlorine is produced at a voltage of 1.73V, meaning the device had to be able to produce meaningful levels of current density with a voltage between the two levels.

The researchers tested the catalysts with seawater drawn from Galveston Bay, off the Texas coast. Ren said it also would work with wastewater.

The work is described in Nature Communications.

Magnets sustainably separate mixtures of rare …

Magnets sustainably separate mixtures of rare earth metals

Seventy-five of the periodic table’s 118 elements are carried in the pockets and purses of more than 100 million U.S. iPhone users every day. Some of these elements are abundant, like silicon in computer chips or aluminum for cases, but certain metals that are required for crisp displays and clear sounds are difficult to obtain. Seventeen elements known as rare earth metals are crucial components of many technologies but are not found in concentrated deposits, and, because they are more dispersed, require toxic and environmentally-damaging procedures to extract.

[…]

With the goal of developing better ways to recycle these metals, new research from the lab of Eric Schelter describes a new approach for separating mixtures of rare earth metals with the help of a magnetic field. The approach, published in Angewandte Chemie International Edition, saw a doubling in separation performance and is a starting point towards a cleaner and more circular rare earth metals economy.

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Light-based ‘tractor beam’ assembles materials…

scifigeneration:

Modern construction is a precision endeavor. Builders must use components manufactured to meet specific standards – such as beams of a desired composition or rivets of a specific size. The building industry relies on manufacturers to create these components reliably and reproducibly in order to construct secure bridges and sound skyscrapers.

Now imagine construction at a smaller scale – less than 1/100th the thickness of a piece of paper. This is the nanoscale. It is the scale at which scientists are working to develop potentially groundbreaking technologies in fields like quantum computing. It is also a scale where traditional fabrication methods simply will not work. Our standard tools, even miniaturized, are too bulky and too corrosive to reproducibly manufacture components at the nanoscale.

Keep reading

Determining the shapes of atomic clusters

Determining the shapes of atomic clusters

Too large to be classed as molecules, but too small to be bulk solids, atomic clusters can range in size from a few dozen to several hundred atoms. The structures can be used for a diverse range of applications, which requires a detailed knowledge of their shapes. These are easy to describe using mathematics in some cases; while in others, their morphologies are far more irregular. However, current models typically ignore this level of detail; often defining clusters as simple ball-shaped structures.

In research published in The European Physical Journal B, José M. Cabrera-Trujillo and colleagues at the Autonomous University of San Luis Potosí in Mexico propose a new method of identifying the morphologies of atomic clusters. They have now confirmed that the distinctive geometric shapes of some clusters, as well as the irregularity of amorphous structures, can be fully identified mathematically.

The insights gathered by Cabrera-Trujillo’s team could make it easier for researchers to engineer atomic clusters for specific applications. These could include nanoparticles containing two different metals, which are highly effective in catalysing chemical reactions. Their updated methods provided new ways to determine the structural properties of clusters, the ways in which they convert energy to different forms, and the potential forces between atoms. The technique was also able to distinguish the surrounding environments of atoms in the cores of clusters, and on their surfaces. Ultimately, this allowed the researchers to distinguish between distinctive shapes, including icosahedrons, octahedrons, and simple pancakes. They were also able to identify amorphous shapes, which contain no discernible mathematical order.

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Monitoring the corrosion of bioresorbable magn…

Monitoring the corrosion of bioresorbable magnesium

Magnesium and its alloys are increasingly being deployed in bone surgery, in particular as osteosynthesis implants such as screws or plates, and as cardiovascular stents to expand narrowed coronary blood vessels.

[…]

This light metal has the great advantage of being bioresorbable – in contrast to the behavior of conventional implant materials such as stainless steel, titanium or polymers. This renders a second surgery to remove an implant from the body unnecessary. Additionally attractive is the fact that magnesium promotes bone growth and therefore actively supports the healing of fractures.

Pure magnesium as such, however, is too soft for deployment in surgical applications, and alloying elements must be added to strengthen it. These are generally rare-?earth elements such as yttrium or neodymium. However, these elements are foreign to the human body and can accumulate in organs during implant degradation, with so far unknown consequences. They are thus particularly inadequate for applications in pediatric surgery.

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Rapid laser solver for the phase retrieval p…

Rapid laser solver for the phase retrieval problem

Physicists can explore tailored physical systems to rapidly solve challenging computational tasks by developing spin simulators, combinatorial optimization and focusing light through scattering media. In a new report on Science Advances, C. Tradonsky and a group of researchers in the Departments of Physics in Israel and India addressed the phase retrieval problem by reconstructing an object from its scattered intensity distribution. The experimental process addressed an existing problem in disciplines ranging from X-ray imaging to astrophysics that lack techniques to reconstruct an object of interest, where scientists typically use indirect iterative algorithms that are inherently slow.

In the new optical approach, Tradonsky et al conversely used a digital degenerate cavity laser (DDCL) mode to rapidly and efficiently reconstruct the object of interest. The experimental results suggested that the gain competition between the many lasing modes acted as a highly parallel computer to rapidly dissolve the phase retrieval problem. The approach applies to two-dimensional (2-D) objects with known compact support and complex-valued objects, to generalize imaging through scattering media, while accomplishing other challenging computational tasks.

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Insulating antiferromagnetic materials for f…

Insulating antiferromagnetic materials for future computers

Future computer technology based on insulating antiferromagnets is progressing. Electrically insulating antiferromagnets such as iron oxide and nickel oxide consist of microscopic magnets with opposite orientations. Researchers see them as promising materials replacing current silicon components in computers. Physicists at Johannes Gutenberg University Mainz (JGU) in collaboration with Tohoku University in Sendai in Japan, the synchrotron sources BESSY-II at Helmholtz-Zentrum Berlin (HZB), and Diamond Light Source, the UK’s national synchrotron, have demonstrated how information can be written and read electrically in insulating antiferromagnetic materials.

By correlating the change in the magnetic structure, observed with synchrotron based imaging, to the electrical measurements performed at JGU, it was possible to identify the writing mechanisms. This discovery opens the way toward applications ranging from ultra-fast logic to credit cards that cannot be erased by external magnetic fields—thanks to the superior properties of antiferromagnets over ferromagnets. The research has been published in Physical Review Letters.

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