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Category: materials – Page 246

Graphene is an allotropic form of carbon and posses some of the unique properties that are making this compound stand out of all other allotropic compounds of carbon. The compound was discovered in modern ages by two scientists Andre Geim and Konstantin Novoselov from the University of Manchester, UK. After its initial discovery the compound soon began to make impact on every field of life and in recognition to their work they were awarded a physics noble prize in 2010. Graphene has unique physical and chemical properties and is much lighter, flexible and strong than many previously existing compounds.

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A team of researchers at the French National Institute of Health and Medical Research in Bordeaux have grown yarn from human skin cells that they call a “human textile” — and they say it could be used by surgeons to close wounds or assemble implantable skin grafts.

“These human textiles offer a unique level of biocompatibility and represent a new generation of completely biological tissue-engineered products,” the researchers wrote in a paper published in the journal Acta Biomaterialia.

The key advantage of the gruesome yarn is that unlike conventional synthetic surgical materials, the material doesn’t trigger an immune response that can complicate the healing process, according to New Scientist.

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Researchers have created a unique device which will unlock the elusive terahertz wavelengths and make revolutionary new technologies possible.

Terahertz waves (THz) sit between microwaves and infrared in the light frequency spectrum, but due to their low-energy scientists have been unable to harness their potential.

The conundrum is known in scientific circles as the terahertz gap.

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A team of researchers, two with the French Atomic Energy Commission (AEC) and a third with the Soleil synchrotron, have found evidence of a phase change for hydrogen at a pressure of 425 gigapascals. In their paper published in the journal Nature, Paul Loubeyre, Florent Occelli and Paul Dumas describe testing hydrogen at such a high pressure and what they learned from it.

Researchers long ago theorized that if gas were exposed to enough pressure, it would transition into a metal. But the theories were not able to derive how much pressure is required. Doubts about the theories began to arise when scientists developed tools capable of exerting the high pressures that were believed necessary to squeeze hydrogen into a metal. Theorists simply moved the number higher.

In the past several years, however, theorists have come to a consensus—their math showed that hydrogen should transition at approximately 425 gigapascals—but a way to generate that much pressure did not exist. Then, last year, a team at the AEC improved on the diamond anvil cell, which for years has been used to create intense pressure in experiments. In a diamond anvil cell, two opposing diamonds are used to compress a sample between highly polished tips—the pressure generated is typically measured using a reference material. With the new design, called a toroidal diamond anvil cell, the tip was made into a donut shape with a grooved dome. When in use, the dome deforms but does not break at high pressures. With the new design, the researchers were able to exert pressures up to 600 GPa. That still left the problem of how to test a sample of hydrogen as it was being squeezed.

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An unusual chunk in a meteorite may contain a surprising bit of space history, based on new research from Washington University in St. Louis.

Presolar —tiny bits of solid interstellar material formed before the sun was born—are sometimes found in primitive meteorites. But a new analysis reveals evidence of presolar grains in part of a where they are not expected to be found.

“What is surprising is the fact that presolar grains are present,” said Olga Pravdivtseva, research associate professor of physics in Arts & Sciences and lead author of a new paper in Nature Astronomy. “Following our current understanding of solar system formation, presolar grains could not survive in the environment where these inclusions are formed.”

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Here on Earth, we pay quite a lot of attention to the sun. It’s visible to us, after all, and central to our lives. But it is only one of the billions of stars in our galaxy, the Milky Way. It’s also quite small compared to other stars – most are at least eight times more massive.

These massive stars influence the structure, shape and chemical content of a galaxy. And when they have exhausted their hydrogen gas fuel and die, they do so in an explosive event called a supernova. This explosion is sometimes so strong that it triggers the formation of new stars out of materials in the dead star’s surroundings.

But there’s an important gap in our knowledge: astronomers don’t yet fully understand how those original massive stars themselves are initially formed. So far, observations have only yielded some pieces of the puzzle.

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To further shrink electronic devices and to lower energy consumption, the semiconductor industry is interested in using 2-D materials, but manufacturers need a quick and accurate method for detecting defects in these materials to determine if the material is suitable for device manufacture. Now a team of researchers has developed a technique to quickly and sensitively characterize defects in 2-D materials.

Two-dimensional materials are atomically thin, the most well-known being graphene, a single-atom-thick layer of carbon atoms.

“People have struggled to make these 2-D materials without defects,” said Mauricio Terrones, Verne M. Willaman Professor of Physics, Penn State. “That’s the ultimate goal. We want to have a 2-D material on a four-inch wafer with at least an acceptable number of defects, but you want to evaluate it in a quick way.”

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