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Category: materials

O, o.

In the world of materials science, many have heard of crystals—highly ordered structures in which atoms are arranged in a tight and periodic manner (in which the atomic arrangement is repeated). But, not many people know about quasicrystals, which are unique structures with strange atomic arrangements. Like crystals, quasicrystals are also tightly arranged, but what’s different about them is the fact that they possess an unprecedented pentagonal symmetry, such that the atomic arrangement is highly ordered but not periodic.

This distinctive feature gives them , like high stability, resistance to heat, and low friction. Since their discovery only about 30 years ago, scientists globally have been trying to understand the properties of quasicrystals, in an effort to make more advancements in materials research. But, this is not easy, as quasicrystals are not prevalent in nature. Luckily, they have been able to make use of structures similar to quasicrystals, called “Tsai-type approximants.” Understanding these structures in detail could give insights into the many properties of quasicrystals. One such property is antiferromagnetism, in which are aligned in a quasiperiodic order, strikingly distinguished from conventional antiferromagnets. This property has never been observed in quasicrystals so far, but the possibility was exciting for materials scientists, as it could be a gateway to a plethora of new applications.

In a new study published in Physical Review B: Rapid Communications, a team of scientists at Tokyo University of Science, led by Prof Ryuji Tamura, found for the first time that a type of Tsai-type approximant exhibits an antiferromagnetic transition. This was an exciting finding, as it suggested that even quasicrystals could show such a transition. The scientists already knew that Tsai-type approximants have two different variants: 1/1 and 2/1 approximants.

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Supermassive black holes are true monsters of the Universe. From millions to even billions of times the mass of the Sun, there’s one in the very center of every big galaxy in the cosmos, and in fact each galaxy itself formed and grew along with its black hole; they affect each other profoundly. As matter falls onto the black hole it falls into an accretion disk, heats up, and emits huge amounts of energy and can also blow a fierce wind of material back into the galaxy (we call such galaxies with actively feeding supermassive black holes active galaxies). This wind can push away gas and dust that would otherwise fall onto the black hole, regulating its growth.

Under some conditions this wind can also compress the gas in the galaxy, which can increase the number of stars forming in the galaxy. But too much wind and the gas is blown right out of the galaxy. Even at some levels in between, it can heat the gas up enough that star formation is much harder. It’s like a pressure valve in the galaxy.

This is how it usually works, at least. Astronomers have found a compact group of galaxies clustered around an active galaxy, and that central galaxy’s black hole is so powerful it’s blowing a wind that’s causing star formation in the galaxies around it!

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Cornell researchers have made a new discovery about how seemingly minor aspects of the internal structure of bone can be strengthened to withstand repeated wear and tear, a finding that could help treat patients suffering from osteoporosis. It could also lead to the creation of more durable, lightweight materials for the aerospace industry.

The team’s paper, “Bone-Inspired Microarchitectures Achieve Enhanced Fatigue Life,” was published Nov. 18 in the Proceedings of the National Academy of Sciences. Co-authors include Cornell doctoral students Cameron Aubin and Marysol Luna; postdoctoral researcher Floor Lambers; Pablo Zavattieri and Adwait Trikanad at Purdue University; and Clare Rimnac at Case Western Reserve University.

For decades, scientists studying osteoporosis have used X-ray imaging to analyze the structure of bones and pinpoint strong and weak spots. Density is the main factor that is usually linked to strength, and in assessing that strength, most researchers look at how much load a bone can handle all at once.

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Regrowing bones is no easy task, but the world’s lightest solid might make it easier to achieve. Researchers have figured out a way to use hybrid aerogels, strong but ultralight materials, to prompt new bone tissue to grow and replace lost or damaged tissue.

Although bone cancer is a relatively rare disease (it accounts for less than 1% of all cancers), people who suffer from it often end up losing a lot of bone tissue and, in extreme cases, undergo amputation. The cancerous tissue has to be cut out, taking with it a large chunk of nearby healthy tissue to make sure that the cancer does not spread. This effectively removes the cancer, but also leaves the patient with a lot less bone than they started out with.

A recent study has used hybrid aerogels to restore the lost tissue by prompting bone regeneration. Aerogels are basically a combination of solid and gas. Think Jell-O, but one where the water has been slowly dried out and replaced completely by air. This slow and careful removing of liquid is what allows the gel to retain its shape instead of shriveling into a hard lump. The pairing of solid and gas makes aerogels extremely light and very porous. These two qualities make them exceptionally suitable to use as scaffolds, which can be used as physical roadmaps for the developing bone to follow as it grows.

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Scientists have long theorized that the energy stored in the atomic bonds of nitrogen could one day be a source of clean energy. But coaxing the nitrogen atoms into linking up has been a daunting task. Researchers at Drexel University’s C&J Nyheim Plasma Institute have finally proven that it’s experimentally possible—with some encouragement from a liquid plasma spark.

Reported in the Journal of Physics D: Applied Physics, the production of pure polymeric nitrogen—polynitrogen—is possible by zapping a compound called sodium azide with a jet of plasma in the middle of a super-cooling cloud of liquid nitrogen. The result is six nitrogen atoms bonded together—a compound called ionic, or neutral, nitrogen-six—that is predicted to be an extremely energy-dense material.

“Polynitrogen is being explored for use as a ‘green’ fuel source, for energy storage, or as an explosive,” said Danil Dobrynin, Ph.D., an associated research professor at the Nyheim Institute and lead author of the paper. “Versions of it have been experimentally synthesized—though never in a way that was stable enough to recover to ambient conditions or in pure nitrogen-six form. Our discovery using liquid plasma opens a new avenue for this research that could lead to a stable polynitrogen.”

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Peak phosphorus is a concept to describe the point in time when humanity reaches the maximum global production rate of phosphorus as an industrial and commercial raw material. The term is used in an equivalent way to the better-known term peak oil.[2] The issue was raised as a debate on whether a “peak phosphorus” was imminent or not around 2010, but was largely dismissed after USGS and other organizations increased the world estimates on available phosphorus resources.[3]

Phosphorus is a finite (limited) resource that is widespread in the Earth’s crust and in living organisms but is relatively scarce in concentrated forms, which are not evenly distributed across the Earth. The only cost-effective production method to date is the mining of phosphate rock, but only a few countries have significant reserves of it. The top four are Morocco, China, Algeria and Syria. Estimates for future production vary significantly depending on modelling and assumptions on extractable volumes, but it is inescapable that future production of phosphate rock will be heavily influenced by Morocco in the foreseeable future.[4]

Means of commercial phosphorus production besides mining are few because the phosphorus cycle does not include significant gas-phase transport.[5] The predominant source of phosphorus in modern times is phosphate rock (as opposed to the guano that preceded it). According to some researchers, Earth’s commercial and affordable phosphorus reserves are expected to be depleted in 50–100 years and peak phosphorus to be reached in approximately 2030.[2][6] Others suggest that supplies will last for several hundreds of years.[7] As with the timing of peak oil, the question is not settled, and researchers in different fields regularly publish different estimates of the rock phosphate reserves.[8].

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For years, physicists have assumed that Cooper pairs, the electron duos that enable superconductors to conduct electricity without resistance, were two-trick ponies. The pairs either glide freely, creating a superconducting state, or create an insulating state by jamming up within a material, unable to move at all.

But in a new paper published in Science, a team of researchers has shown that Cooper pairs can also conduct electricity with some amount of resistance, like regular metals do. The findings describe an entirely new state of matter, the researchers say, that will require a new theoretical explanation.

“There had been evidence that this would arise in thin film superconductors as they were cooled down toward their , but whether or not that state involved Cooper pairs was an open question,” said Jim Valles, a professor of physics at Brown University and the study’s corresponding author. “We’ve developed a technique that enables us to test that question and we showed that, indeed, Cooper pairs are responsible for transporting charge in this metallic state. What’s interesting is that no one is quite sure at a fundamental level how they do that, so this finding will require some more theoretical and to understand exactly what’s happening.”

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