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Category: materials – Page 3

Physically Intuitive Anisotropic Model of Hardness https://arxiv.org/abs/2412.

Skoltech researchers have presented a new simple physical model for predicting the hardness of materials based on information about the shear modulus and equations of the state of crystal structures. The model is useful for a wide range of practical applications—all parameters in it can be determined through basic calculations or measured experimentally.

The results of the study are presented in the Physical Review Materials journal.

Hardness is an important property of materials that determines their ability to resist deformations and other damage (dents, scratches) due to external forces. It is typically determined by pressing the indenter into the test sample, and the indenter must be made of a harder material, usually diamond.

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The night sky has always played a crucial role in navigation, from early ocean crossings to modern GPS. Besides stars, the United States Navy uses quasars as beacons. Quasars are distant galaxies with supermassive black holes, surrounded by brilliantly hot disks of swirling gas that can blast off jets of material.

Following up on the groundbreaking 2020 discovery of newborn jets in a number of quasars, aspiring naval officer Olivia Achenbach of the United States Naval Academy has used NASA’s Hubble Space Telescope to reveal surprising properties of one of them, quasar J0742+2704.

“The biggest surprise was seeing the distinct spiral shape in the Hubble Space Telescope images. At first I was worried I had made an error,” said Achenbach, who made the discovery during the course of a four-week internship.

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Once upon a time, the core of a massive star collapsed, creating a shockwave that blasted outward, ripping the star apart as it went. When the shockwave reached the star’s surface, it punched through, generating a brief, intense pulse of X-rays and ultraviolet light that traveled outward into the surrounding space. About 350 years later, that pulse of light has reached interstellar material, illuminating it, warming it, and causing it to glow in infrared light.

NASA’s James Webb Space Telescope has observed that infrared glow, revealing fine details resembling the knots and whorls of wood grain. These observations are allowing astronomers to map the true 3D structure of this interstellar dust and gas (known as the interstellar medium) for the first time.

“We were pretty shocked to see this level of detail,” said Jacob Jencson of Caltech/IPAC in Pasadena, principal investigator of the science program.

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UCLA materials scientists have developed a compact cooling technology that can pump away heat continuously using layers of flexing thin films. The design is based on the electrocaloric effect, in which an electric field causes a temporary change in a material’s temperature.

In lab experiments, the researchers found that the prototype could lower ambient temperatures of its immediate surroundings by 16 degrees Fahrenheit continuously and up to 25 degrees at the source of the heat after about 30 seconds.

Detailed in a paper published in the journal Science, the approach could be incorporated into wearable technology or portable cooling devices.

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GE Aerospace is advancing hypersonic flight with plans to scale up its dual-mode ramjet technology in 2025.

To create a full propulsion system, engineers will improve sophisticated controls and use state-of-the-art materials from jet engine advancements in the upcoming months. This will be a crucial step in reaching flying capabilities.

An sophisticated hypersonic dual-mode ramjet that can handle high-speed, long-range flying across a variety of multi-mission aircraft was unveiled by GE Aerospace in July 2024.

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Stanford researchers have uncovered a new material, niobium phosphide, that surpasses copper in electrical conductivity when fashioned into ultrathin films.

This breakthrough could revolutionize the efficiency and performance of future electronics by alleviating the limitations posed by traditional metal wires in nanoscale circuits.

Nanoscale Electronics Challenges

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