fuckyeahfluiddynamics:

fuckyeahfluiddynamics:

Defrosting and deicing surfaces is an energy-intensive affair, with lots of heat lost to warming up system components rather than the ice itself. In a new study, researchers explore a faster and more efficient method that focuses on heating just the interface. They coated their working surface in a thin layer of iridium tin oxide, a conductive film used in defrosting. Then, once the surface was iced over, they applied a 100 ms pulse of heating to the film. That localized heat melted the interface, and gravity pulled away the detached ice. Compared to conventional defrosting methods, this technique requires only 1% of the energy and 0.01% of the time. If the method scales reliably to applications like airplane deicing, it would provide enormous savings in time and energy. (Image and research credit: S. Chavan et al.)

Oxide scale in X45NiCrMo4 steel Inclusion nam…

Oxide scale in X45NiCrMo4 steel

Inclusion name: Iron oxide
Record No.: 1490
Inclusion formula: No data
Inclusion type (Macro/Micro/Nano): Macro
Inclusion type (Exogenous/Indigenous): Exogenous
Inclusion classification: Oxide
Inclusion composition in weight %: No data
Sample: X45NiCrMo4 steel
Steel composition in weight %: 0.45% C, 0.24% Si, 0.27% Mn, 0.011% P, 0.005% S, 1.31% Cr, 4.00% Ni, 0.18% Mo, 0.11% Cu, 0.008% Al.
Note: Nickel cold work tool steel
Reference: Not shown in this demo version.

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Zinc oxide nanowires: Novel solution for che…

Zinc oxide nanowires: Novel solution for cheaper, cleaner production of electronic components

Although nanowires are answering the demands of the market for innovative, smaller, flexible electronic devices by enabling electronic circuits on the molecular scale, assembly of nanowires into functional materials remains a problem. Group of researchers from Kaunas University of Technology (KTU), Lithuania are offering a novel solution for high-yield nanowire production from zinc oxide—cheaper and environmentally friendlier material, compared to the rare earth elements such as indium, arsenic or gallium often used in electronics production.

According to scientists, nanowires’ synthesis is mostly limited by the surface of growth, hindering their wide application. Also, many applications require properties, which are contradictive and therefore cannot be effectively realised in a single material. The new method for zinc oxide nanowires production, created by the group of scientists from KTU Institute of Materials Science, tackles these problems. Thus the wider application of nanowires in innovative electronic devices, which are increasingly smaller, flexible and involving different surface materials is becoming possible.

“The new method was created while I was researching simple ways to grow metal oxide nanostructures. The method, which we now call combustion synthesis, allows producing high levels of a controlled nanostructure. Nanowires are being grown in the gas phase, the final product collected as powder and then dispersed in various solutions. Simple coating methods such as spraying allow placing zinc oxide nanowires on various surfaces”, says Dr. Simas Račkauskas, a researcher at the KTU Institute of Materials Science.

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A novel graphene-matrix-assisted stabilizati…

A novel graphene-matrix-assisted stabilization method will help 2-D materials become a part of quantum computers

Scientists from Russia and Japan found a way of stabilizing two-dimensional copper oxide (CuO) materials by using graphene. Along with being the main candidates for spintronics applications, these materials may be used in forthcoming quantum computers. The results of the study were published in The Journal of Physical Chemistry C.

The family of 2-D materials has recently been joined by a new class, the monolayers of oxides and carbides of transition metals, which have been the subject of extensive theoretical and experimental research. These new materials are of great interest to scientists due to their unusual rectangular atomic structure and chemical and physical properties, and in particular, a unique 2-D rectangular copper oxide cell which does not exist in crystalline (3-D) form, as opposed to most of the 2-D materials, whether well-known or discovered lately, which have a lattice similar to that of their crystalline (3-D) counterparts. The main hindrance for practical use of monolayers is their low stability.

A group of scientists from MISiS, the Institute of Biochemical Physics of RAS (IBCP), Skoltech, and the National Institute for Materials Science in Japan (NIMS) discovered 2-D copper oxide materials with an unusual crystal structure inside the two-layer graphene matrix using experimental methods.

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Ultra-thin layers of rust generate electricity from flowing water

There are many ways to generate electricity – batteries, solar panels, wind turbines, and hydroelectric dams, to name a few examples. …. And now there’s rust.

New research conducted by scientists at Caltech and Northwestern University shows that thin films of rust – iron oxide – can generate electricity when saltwater flows over them. These films represent an entirely new way of generating electricity and could be used to develop new forms of sustainable power production.

Interactions between metal compounds and saltwater often generate electricity, but this is usually the result of a chemical reaction in which one or more compounds are converted to new compounds. Reactions like these are what is at work inside batteries.

In contrast, the phenomenon discovered by Tom Miller, Caltech professor of chemistry, and Franz Geiger, Dow Professor of Chemistry at Northwestern, does not involve chemical reactions, but rather converts the kinetic energy of flowing saltwater into electricity.

The phenomenon, the electrokinetic effect, has been observed before in thin films of graphene – sheets of carbon atoms arranged in a hexagonal lattice – and it is remarkably efficient. The effect is around 30 percent efficient at converting kinetic energy into electricity. For reference, the best solar panels are only about 20 percent efficient.

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A catalyst for sustainable methanol

The global economy still relies on the fossil carbon sources of petroleum, natural gas and coal, not just to produce fuel, but also as a raw material used by the chemical industry to manufacture plastics and countless other chemical compounds. Although efforts have been made for some time to find ways of manufacturing liquid fuels and chemical products from alternative, sustainable resources, these have not yet progressed beyond niche applications.

Scientists at ETH Zurich have now teamed up with the French oil and gas company Total to develop a new technology that efficiently converts CO2 and hydrogen directly into methanol. Methanol is regarded as a commodity or bulk chemical. It is possible to convert it into fuels and a wide variety of chemical products, including those that today are mainly based on fossil resources. Moreover, methanol itself has the potential to be utilised as a propellant, in methanol fuel cells, for example.

Nanotechnology

The core of the new approach is a chemical catalyst based on indium oxide, which was developed by Javier Pérez-Ramírez, Professor of Catalysis Engineering at ETH Zurich, and his team. Just a few years ago, the team successfully demonstrated in experiments that indium oxide was capable of catalysing the necessary chemical reaction. Even at the time, it was encouraging that doing so generated virtually only methanol and almost no by-products other than water. The catalyst also proved to be highly stable. However, indium oxide was not sufficiently active as a catalyst; the large quantities needed prevent it from being a commercially viable option.

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Search for new semiconductors heats up with gallium oxide

University of Illinois electrical engineers have cleared another hurdle in high-power semiconductor fabrication by adding the field’s hottest material – beta-gallium oxide – to their arsenal. Beta-gallium oxide is readily available and promises to convert power faster and more efficiently than today’s leading semiconductor materials – gallium nitride and silicon, the researchers said.

Their findings are published in the journal ACS Nano.

Flat transistors have become about as small as is physically possible, but researchers addressed this problem by going vertical. With a technique called metal-assisted chemical etching – or MacEtch – U. of I. engineers used a chemical solution to etch semiconductor into 3D fin structures. The fins increase the surface area on a chip, allowing for more transistors or current, and can therefore handle more power while keeping the chip’s footprint the same size.

Developed at the U. of I., the MacEtch method is superior to traditional “dry” etching techniques because it is far less damaging to delicate semiconductor surfaces, such as beta-gallium oxide, researchers said.

“Gallium oxide has a wider energy gap in which electrons can move freely,” said the study’s lead author Xiuling Li, a professor of electrical and computer engineering. “This energy gap needs to be large for electronics with higher voltages and even low-voltage ones with fast switching frequencies, so we are very interested in this type of material for use in modern devices. However, it has a more complex crystal structure than pure silicon, making it difficult to control during the etching process.”

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Eco-friendly composite catalyst and ultrasound removes pollutants from water

The research team of Dr. Jae-woo Choi and Dr. Kyung-won Jung of the Korea Institute of Science and Technology’s (KIST, president: Byung-gwon Lee) Water Cycle Research Center announced that it has developed a wastewater treatment process that uses a common agricultural byproduct to effectively remove pollutants and environmental hormones, which are known to be endocrine disruptors.

The sewage and wastewater that are inevitably produced at any industrial worksite often contain large quantities of pollutants and environmental hormones (endocrine disruptors). Because environmental hormones do not break down easily, they can have a significant negative effect on not only the environment but also the human body. To prevent this, a means of removing environmental hormones is required.

The performance of the catalyst that is currently being used to process sewage and wastewater drops significantly with time. Because high efficiency is difficult to achieve given the conditions, the biggest disadvantage of the existing process is the high cost involved. Furthermore, the research done thus far has mostly focused on the development of single-substance catalysts and the enhancement of their performance. Little research has been done on the development of eco-friendly nanocomposite catalysts that are capable of removing environmental hormones from sewage and wastewater.

The KIST research team, led by Dr. Jae-woo Choi and Dr. Kyung-won Jung, utilized biochar, which is eco-friendly and made from agricultural byproducts, to develop a wastewater treatment process that effectively removes pollutants and environmental hormones. The team used rice hulls, which are discarded during rice harvesting, to create a biochar** that is both eco-friendly and economical. The surface of the biochar was coated with nano-sized manganese dioxide to create a nanocomposite. The high efficiency and low cost of the biochar-nanocomposite catalyst is based on the combination of the advantages of the biochar and manganese dioxide.

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Magnetite nanowires with sharp insulating tr…

Magnetite nanowires with sharp insulating transition

Magnetite (Fe3O4) is best known as a magnetic iron ore, and is the source of lodestone. It also has potential as a high-temperature resistor in electronics. In new research led by Osaka University, published in Nano Letters, ultra-thin nanowires made from Fe3O4 reveal insights into an intriguing property of this mineral.

When cooled to around 120 K (−150°C), magnetite suddenly shifts from a cubic to a monoclinic crystal structure. At the same time, its conductivity sharply drops—it is no longer a metal but an insulator. The exact temperature of this unique “Verwey transition,” which can be used for switching in electronic devices, depends on the sample’s properties, like grain size and particle shape.

Magnetite can be made into thin films, but below a certain thickness—around 100 nm—the Verwey transition weakens and needs lower temperatures. Thus, for electronics at the nano-scale, preserving this key feature of Fe3O4 is a major challenge. The Osaka study used an original technique to produce magnetite nanowires of just 10 nanometer length, which had exquisite Verwey behavior.

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A device emerges from the fusion of IGZO and…

A device emerges from the fusion of IGZO and ferroelectric-HfO2

As a part of JST PRESTO program, Associate professor Masaharu Kobayashi, Institute of Industrial Science, the University of Tokyo, has developed a ferroelectric FET (FeFET) with ferroelectric-HfO2 and ultrathin IGZO channel. Nearly ideal subthreshold swing (SS) and mobility higher than poly-silicon channel have been demonstrated.

FeFET is a promising memory device because of its low-power, high-speed and high-capacity. After the discovery of CMOS-compatible ferroelectric-HfO2 material, FeFET has been attracting more attention. For even higher memory capacity, 3-D vertical stack structure has been proposed as shown in Fig. 1(a).

For 3-D vertical stack structure, poly-silicon is typically used as a channel material. However, poly-silicon has very low mobility in nanometer thickness region due to grain boundaries and extrinsic defects. Moreover, poly-silicon forms a low-k interfacial layer with ferroelectric-HfO2 gate insulator. This results in voltage loss and charge trapping which prevents low voltage operation and degrades reliability, respectively as shown in Fig. 1(b).

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