Materials

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The chemistry of hafnium dioxide (known as hafina) is rather boring. Yet, the behavior of ultrathin layers that are based on this material is very interesting: they can be used as non-volatile computer memory through the switching of dipoles with an electric field. And as the dipole strength depends on the history of the electric field, it is suitable for the construction of memristors for 'brain-like' computer architectures. Beatriz Noheda, Professor of Functional Nanomaterials at the University of Groningen, has studied the material and recently wrote a Perspective article on its properties for the journal Nature Materials. "It is already used in devices, even though we do not understand all of the physics." To create more efficient computers, fast non-volatile random-access memory (RAM) is required. Ferroelectric materials appeared to be good candidates. These materials are made up of units with dipoles that will switch collectively using an electric field. However, their properties break down if the number of units is too small; spontaneous depolarization occurs below approximately 90 nanometers.

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Many researchers dream of deciphering the amazing ability of spiders to create super strong, super light, and super flexible silk threads—but so far, no one has been able to replicate the spiders' work. Should it one day become possible to produce a synthetic material with the same properties, a whole new world of possibilities may open: Artificial spider silk could replace materials like Kevlar, polyester, and carbon fiber in industries and be used, for example, to make lightweight and flexible bulletproof vests. Postdoc and biophysicist Irina Iachina from the Department of Biochemistry and Molecular Biology, University of Southern Denmark (SDU), is involved in this race to uncover the recipe for super silk. She has been fascinated by spider silk since her time as a master's student at SDU, and currently, she is researching the topic at the Massachusetts Institute of Technology in Boston with support from the Villum Foundation. As part of her research, she is collaborating with associate professor and biophysicist Jonathan Brewer at SDU, who is an expert in using various types of microscopes to peer into biological structures.

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Targeted alpha therapy can destroy cancerous cells without harming healthy cells. It's especially useful for treating metastasized cancers. The Department of Energy (DOE) Office of Science's Isotope Program is developing and marketing novel radioactive isotopes for targeted alpha therapy. One method of making one isotope, actinium-225, involves bombarding radium targets with neutrons. This method poses a challenge: how to chemically separate the radium from the actinium. This can destroy typical separation equipment due to a radioactive process called alpha decay. Now, researchers have investigated the use of radiation-resistant inorganic resin scaffolds as platforms for separating radium, actinium, and lead. Demand and production of actinium-225 (Ac-225) and other alpha-emitting radioisotopes are increasing. These new types of resins will support the purification and distribution of these lifesaving isotopes. As production increases, radiation levels will also increase. Chemical processes need to be robust in these hazardous environments. These new resins and this recent research will help producers save time, effort, and costs while reducing the risks of manufacturing alpha-emitting radioisotopes.

Cleaner air with a cold catalytic converter: A new catalyst can purify exhaust gases at room temperature

Although passenger vehicle catalytic converters have been mandatory for over 30 years, there is still plenty of room for improvement. For in

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Although passenger vehicle catalytic converters have been mandatory for over 30 years, there is still plenty of room for improvement. For instance, they only work correctly when the engine is sufficiently hot, which is not always the case, especially with hybrid vehicles. Researchers from Eindhoven University of Technology (TU/e), together with colleagues from the University of Antwerp, have developed an improved catalyst that can properly purify exhaust gases even at room temperature. Their work is published in the journal Science on June 16th. The so-called three-way catalytic converter in the exhaust system of a car consists of expensive materials and only works correctly when the exhaust gases have a temperature that is several hundred degrees Celsius. As a result, when you start your car, or when you drive a hybrid car in which the petrol engine and electric motor alternate between driving the powertrain, the gases leaving the exhaust still contain toxic carbon monoxide. In a new Science article, scientists led by Emiel Hensen now show that by modifying the carrier material of the catalyst, it is possible to almost completely convert toxic carbon monoxide into carbon dioxide gas even at room temperature.

This amorphous metal has a coefficient or restitution or 0.99 when paired with a ball bearing. It's like watching a glitch in the matrix! Thanks to Grand Illusions for lending me the atomic trampoline: https://www.grand-illusions.com

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An advance in a topological insulator material—whose interior behaves like an electrical insulator but whose surface behaves like a conductor—could revolutionize the fields of next-generation electronics and quantum computing, according to scientists at Oak Ridge National Laboratory. Discovered in the 1980s, a topological material is a new phase of material whose discoverers received a Nobel Prize in 2016. Using only an electric field, ORNL researchers have transformed a normal insulator into a magnetic topological insulator. This exotic material allows electricity to flow across its surface and edges with no energy dissipation. The electric field induces a change in the state of matter. The ORNL scientists have published their findings in 2D Materials.

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Twistronics isn't a new dance move, exercise equipment, or new music fad. No, it's much cooler than any of that. It is an exciting new development in quantum physics and material science where van der Waals materials are stacked on top of each other in layers, like sheets of paper in a ream that can easily twist and rotate while remaining flat, and quantum physicists have used these stacks to discover intriguing quantum phenomena. Adding the concept of quantum spin with twisted double bilayers (tDB) of an antiferromagnet, it is possible to have tunable moiré magnetism. This suggests a new class of material platform for the next step in twistronics: spintronics. This new science could lead to promising memory and spin-logic devices, opening the world of physics up to a whole new avenue with spintronic applications. Now, a team of quantum physics and materials researchers has introduced the twist to control the spin degree of freedom, using CrI3, an interlayer-antiferromagnetic-coupled vdW material, as their medium. Their findings were published in Nature Electronics on June 19, 2023.

Treatment creates steel alloys with superior strength and plasticity

A new treatment for high-quality steel alloys appears to confer super-plasticity in a manner researchers cannot fully explain.

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A new treatment tested on a high-quality steel alloy produces extraordinary strength and plasticity, two traits that must typically be balanced rather than combined. Ultra-fine metal grains that the treatment produced in the outermost layer of steel appear to stretch, rotate and then elongate under strain, conferring super-plasticity in a way that Purdue University researchers cannot fully explain. The researchers treated T-91, a modified steel alloy that is used in nuclear and petrochemical applications, but said the treatment could be used in other places where strong, ductile steel would be beneficial, such as cars axles, suspension cables and other structural components. The research, which was conducted in collaboration with Sandia National Laboratories and has been patented, appeared Wednesday, May 31 in Science Advances. More intriguing even than the immediate result of a stronger, more plastic variant of T-91 are observations made at Sandia showing characteristics of what the team is calling a "nanolaminate" of ultra-fine metal grains the treatment created in a region extending from the surface to a depth of about 200 microns. Microscopy images show an unexpected deformation of the treated steel -dubbed G-T91 (or gradient T91) -- as it is subjected to increasing stress, said Xinghang Zhang, lead author and a professor in the School of Materials Engineering at Purdue.

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Nuclear power is typically considered a cleaner way of generating power compared to fossil fuels. It does not release air pollutants and greenhouse gasses like carbon dioxide as by-products. However, it creates radiotoxic waste that needs proper treatment to prevent adverse environmental and health conditions. One of the major by-products of the nuclear fission process used for power generation is 137Cs (an isotope of cesium), a radioactive element that has a half-life of 30 years and is often removed from nuclear powerplant (NPP) wastewater via selective adsorption using ion exchangers. However, this process is severely hindered in acidic wastewater where excess protons (H+) impair the adsorption ability and damage the lattice structure of the adsorbent. Recently, a team of researchers led by Prof. Kuk Cho from Pusan National University, Korea, found a way to turn this adversity into an advantage. In their breakthrough work in Journal of Hazardous Materials they have presented potassium calcium thiostannate (KCaSnS), a new layered calcium (Ca2+)-doped chalcogenide ion exchanger. It utilizes the typically problematic H+ ions in acidic wastewater to enhance the cesium ion (Cs+) adsorption process. Essentially, the Ca2+ ions from KCaSnS are leached out by H+ and Cs+, making way for Cs+.

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A quartet of chemists at the University of Oxford has, for the first time, found a way to get two beryllium atoms to bond with one another. In their paper published in the journal Science, Josef Boronski, Agamemnon Crumpton, Lewis Wales and Simon Aldridge, describe their process and how they managed to do it in a safe way—and at room temperature. Jason Dutton with La Trobe University, has published a Perspective piece in the same journal issue, outlining the work done by the team in England. Beryllium is a strong but lightweight, alkaline earth metal. It is also brittle. Beryllium only ever occurs naturally when mixed with other elements, forming minerals. It is often found in gemstones such as emeralds. And it is used in a variety of applications, from telecommunications equipment to computers and cell phones. It is also mixed with other metals to create alloys used in applications such as gyroscopes and electrical contacts. For many years, scientists have thought that the element could be even more useful if a way could be found to force beryllium atoms to bond with one another. But until now, it was not possible.

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It is hard to imagine our daily lives without plastics made out of polyolefins. Unfortunately, practical methods for recycling of polyolefins are lacking. In the journal Angewandte Chemie, a research team has now introduced a new approach for making novel polyolefins that can be chemically deconstructed and re-polymerized without a loss of quality. The secret to the method is masked double bonds introduced to the polymer chain by means of a so-called "Trojan horse" functional group in the polymer chain. Polyolefins are stable, light, versatile, and inexpensive plastics made of very long hydrocarbon chains. However, their high stability and durability come with a drawback: after use, polyolefins are extremely persistent in the environment. Mechanical recycling forms products with inferior properties. The high chemical stability of polyolefins also inhibits chemical depolymerization to get back the monomers. It would be more sustainable to have a circular economy based on alternative, chemically recyclable polyolefins that could be disassembled into smaller fragments, purified, and polymerized again. These smaller fragments are also more likely to be biodegradable if they accidentally enter into the environment.

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Extremely intense X-ray pulses can determine the positions of some hydrogen atoms in organic molecules that form small crystals, an all-RIKEN team has shown. Many areas, including drug discovery and materials research, stand to benefit from this demonstration. Ever since William Lawrence Bragg and his father William Henry Bragg demonstrated that X-rays scattered from crystals produce distinctive patterns 110 years ago, X-ray diffraction has been the technique of choice for determining the structure of crystalline materials. However, many materials form crystals that are too small to be analyzed by X-ray diffraction. "Because many compounds cannot be obtained in large crystals, the ability to analyze the structures of small crystals is important in fields such as synthetic organic chemistry, pharmaceutical science and materials science," says Koji Yonekura of the RIKEN SPring-8 Center. Switching from X-rays to electrons can allow the structures of smaller crystals to be determined, but it has the downside that it requires very thin samples.

Megawatt electrical motor designed by engineers could help electrify aviation: Technology demonstrations show the machine's major components

Aerospace engineers designed a 1-megawatt electrical motor that is a stepping stone toward electrifying the largest aircraft.

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Aviation's huge carbon footprint could shrink significantly with electrification. To date, however, only small all-electric planes have gotten off the ground. Their electric motors generate hundreds of kilowatts of power. To electrify larger, heavier jets, such as commercial airliners, megawatt-scale motors are required. These would be propelled by hybrid or turbo-electric propulsion systems where an electrical machine is coupled with a gas turbine aero-engine. To meet this need, a team of MIT engineers is now creating a 1-megawatt motor that could be a key stepping stone toward electrifying larger aircraft. The team has designed and tested the major components of the motor, and shown through detailed computations that the coupled components can work as a whole to generate one megawatt of power, at a weight and size competitive with current small aero-engines. For all-electric applications, the team envisions the motor could be paired with a source of electricity such as a battery or a fuel cell. The motor could then turn the electrical energy into mechanical work to power a plane's propellers. The electrical machine could also be paired with a traditional turbofan jet engine to run as a hybrid propulsion system, providing electric propulsion during certain phases of a flight.

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Massachusetts Institute of Technology engineers have synthesized a superabsorbent material that can soak up a record amount of moisture from the air, even in desert-like conditions. As the material absorbs water vapor, it can swell to make room for more moisture. Even in very dry conditions, with 30% relative humidity, the material can pull vapor from the air and hold in the moisture without leaking. The water could then be heated and condensed, then collected as ultra-pure water. The transparent, rubbery material is made from hydrogel, a naturally absorbent material that is also used in disposable diapers. The team enhanced the hydrogel's absorbency by infusing it with lithium chloride—a type of salt that is known to be a powerful dessicant. The researchers found they could infuse the hydrogel with more salt than was possible in previous studies. As a result, they observed that the salt-loaded gel absorbed and retained an unprecedented amount of moisture, across a range of humidity levels, including very dry conditions that have limited other material designs.

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A team of chemists and engineers affiliated with a large number of institutions in China has found that using liquid metal to synthesize high-entropy alloy nanoparticles (HEA-NPs) is a viable alternative to conventional methods. In their study, reported in the journal Nature, the group attempted to create a variety of HEA-NPs using liquid metals. The editors at Nature have published a Research Briefing in the same journal issue outlining the work. High-entropy alloys are materials that contain at least five kinds of metals that exhibit useful qualities unobtainable in individual metals. Similarly, HEA-NPs are tiny particles containing a host of metals that have useful properties in combination. However, synthesizing HEA-NPs has proven to be a challenge, particularly getting them to mix evenly. Current methods typically involve heating mixtures to temperatures as high as 2,000 Kelvin, which is dangerous and expensive. In this new effort, the team in China is claiming to have found a much better way.

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Do an image search for "electronic implants," and you'll draw up a wide assortment of devices, from traditional pacemakers and cochlear implants to more futuristic brain and retinal microchips aimed at augmenting vision, treating depression, and restoring mobility. Some implants are hard and bulky, while others are flexible and thin. But no matter their form and function, nearly all implants incorporate electrodes—small conductive elements that attach directly to target tissues to electrically stimulate muscles and nerves. Implantable electrodes are predominantly made from rigid metals that are electrically conductive by nature. But over time, metals can aggravate tissues, causing scarring and inflammation that in turn can degrade an implant's performance.