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Category: materials – Page 210

For decades, there has been a trend in microelectronics towards ever smaller and more compact transistors. 2D materials such as graphene are seen as a beacon of hope here: they are the thinnest material layers that can possibly exist, consisting of only one or a few atomic layers. Nevertheless, they can conduct electrical currents—conventional silicon technology, on the other hand, no longer works properly if the layers become too thin.

However, such materials are not used in a vacuum; they have to be combined with suitable insulators—in order to seal them off from unwanted environmental influences, and also in order to control the flow of current via the so-called field effect. Until now, hexagonal boron nitride (hBN) has frequently been used for this purpose as it forms an excellent environment for 2D materials. However, studies conducted by TU Wien, in cooperation with ETH Zurich, the Russian Ioffe Institute and researchers from Saudi Arabia and Japan, now show that, contrary to previous assumptions, thin hBN layers are not suitable as insulators for future miniaturized field-effect transistors, as exorbitant leakage currents occur. So if 2D materials are really to revolutionize the , one has to start looking for other insulator materials. The study has now been published in the scientific journal Nature Electronics.

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‘A class of subluminal, spherically symmetric warp drive spacetimes, at least in principle, can be constructed based on the physical principles known to humanity today,’ the scientists say.

“Conceptually, we demonstrate that any warp drive, including the Alcubierre drive, is a shell of regular or exotic material moving inertially with a certain velocity. Therefore, any warp drive requires propulsion. We show that a class of subluminal, spherically symmetric warp drive spacetimes, at least in principle, can be constructed based on the physical principles known to humanity today.”

The scientists’ theories are based on the Alcubierre warp drive, named after theoretical physicist Miguel Alcubierre. In his paper’s abstract, published in 2000, he wrote that the drive world work by modifying spacetime.

“By a purely local expansion of spacetime behind the spaceship and an opposite contraction in front of it, motion faster than the speed of light as seen by observers outside the disturbed region is possible,” Alcubierre wrote.

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Study describes passive cooling system that aims to help impoverished communities, reduce cooling and heating costs, lower CO2 emissions.

Passive cooling, like the shade a tree provides, has been around forever.

Recently, researchers have been exploring how to turbo charge a passive cooling technique — known as radiative or sky cooling — with sun-blocking, nanomaterials that emit heat away from building rooftops. While progress has been made, this eco-friendly technology isn’t commonplace because researchers have struggled to maximize the materials’ cooling capabilities.

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Advertisement The device for sweeping mines is built using low-cost material available in abundance, hence easily replaceable too. The new mine killer device known as Mine Kafon, developed by an Afghan designer, is an expertly designed device that uses cheap materials that are easily replaceable, hence giving tremendous results.

The device is wind-powered and seems like a Hoberman sphere. The device’s weight and height match that of an average-sized man, hence replicating the effect of a man stepping on a mine.

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A large international team of scientists from various research organizations, including the U.S. Department of Energy’s (DOE) Argonne National Laboratory, has developed a method that dramatically improves the already ultrafast time resolution achievable with X-ray free-electron lasers (XFELs). It could lead to breakthroughs on how to design new materials and more efficient chemical processes.

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Scientists based at the University of Oxford as part of the Faraday Institution CATMAT project researching next-generation cathode materials have made a significant advance in understanding oxygen-redox processes involved in lithium-rich cathode materials. The paper, published in Nature Energy, proposes strategies that offer potential routes to increase the energy density of lithium-ion batteries.

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Surprise in solid-state physics: The Hall effect, which normally requires magnetic fields, can also be generated in a completely different way – with extreme strength.

Electric current is deflected by a magnetic field – in conducting materials this leads to the so-called Hall effect. This effect is often used to measure magnetic fields. A surprising discovery has now been made at TU Wien, in collaboration with scientists from the Paul Scherrer Institute (Switzerland), McMater University (Canada), and Rice University (USA): an exotic metal made of cerium, bismuth, and palladium was examined and a giant Hall effect was found to be produced by the material, in the total absence of any magnetic field. The reason for this unexpected result lies in the unusual properties of the electrons: They behave as if magnetic monopoles were present in the material. These discoveries have now been published in the scientific magazine PNAS.

A voltage perpendicular to the current.

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