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Category: materials – Page 252

Radiative Cooling and Solar Heating From One System – No Electricity Needed

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.

This Afghan-Developed ‘Mine Kafon’ Ball Detonates Landmines At A Cheaper Cost

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.

Breakthrough greatly enhances ultrafast resolution achievable with X-ray free-electron lasers

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.

Furthering mechanistic understanding of oxygen-redox processes in lithium-rich battery cathodes

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.

Surprise in Solid-State Physics: Magnetic Effect Without a Magnet

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.

Increasing optical data transmission speed

Pulsed lasers repeatedly emit light for a short period of time as if blinking. They have the advantage of focusing more energy than a continuous wave laser, whose intensity is kept unchanged over time. If digital signals are loaded in a pulsed laser, each pulse can encode one bit of data. In this respect, the higher the repetition rate, the more the amount of data that can be transmitted. However, conventional optical-fiber-based pulsed lasers have typically had a limitation in increasing the number of pulses per second above the MHz level.

The Korea Institute of Science and Technology (KIST) announced that the research team led by Senior Researcher Dr. Yong-Won Song at the Center for Opto-Electronic Materials and Devices was able to generate at a rate at least 10000 times higher than the state of the art. This achievement was accomplished by inserting an additional resonator containing graphene into a fiber-optic pulsed– oscillator that operates in the domain of femtoseconds (10-15 seconds). The data transmission and processing speeds are expected to increase significantly by applying this method to data communications.

The KIST research team noted that the characteristics of the wavelength and intensity of laser light that change over time are correlated (Fourier transform). If a resonator is inserted into the laser oscillator, the wavelength of the pulsed laser is periodically filtered, thereby modifying the pattern of laser intensity change. Based on this background research, Principal Researcher Song synthesized graphene, which has the characteristics of absorbing and eliminating weak light and amplifying the intensity by passing only strong light into the resonator. This allows the laser intensity change to be accurately controlled at a high rate, and thus the repetition rate of pulses could be increased to a higher level.

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