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Category: materials – Page 174

We all know that light and sound are wave phenomena, but of very different kinds. Light is electromechanical in nature, while sound is mechanical. Light can travel through a vacuum, while sound needs some sort of medium to transmit it. So it would seem that it might be difficult to use sound to modify light, but with the right equipment, it’s actually pretty easy.

Easy, perhaps, if you’re used to slinging lasers around and terms like “acousto-optic tunable filter” fall trippingly from your tongue, as is the case for [Les Wright]. An AOTF is a device that takes a radio frequency input and applies it to a piezoelectric transducer that’s bonded to a crystal of tellurium oxide. The RF signal excites the transducer, which vibrates the TeO2 crystal and sets up a standing wave within it. The alternating bands of compressed and expanded material within the crystal act like a diffraction grating. Change the excitation frequency, and the filter’s frequency changes too.

To explore the way sound can bend light, [Les] picked up a commercial AOTF from the surplus market. Sadly, it didn’t come with the RF driver, but no matter — a few quick eBay purchases put the needed RF generator and power amplifier on his bench. The modules went into an enclosure to make the driver more of an instrument and less of a one-off, with a nice multi-turn pot and vernier knob for precise filter adjustment. It’s really kind of cool to watch the output beam change colors at the twist of a knob, and cooler still to realize how it all works.

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Most integrated circuits (ICs) and electronic components developed to date are based on silicon metal-oxide-semiconductor (CMOS) technology. As silicon (Si) is known to have a narrow bandgap, however, in recent years engineers have been trying to develop ICs using other materials with a wider bandgap, such as gallium nitrite (GaN).

ICs made of GaN could have notable advantages over conventional ICs based on silicon, particularly for the development of power electronics, radiofrequency power amplifiers and devices designed to operate in harsh environments. However, so far developing GaN CMOS has proved to be highly challenging, due to the intrinsically low mobility of holes in the material and the lack of a suitable strategy for integrating n-channel and p-channel field-effect transistors (n-FETs and p-FETs) on a single substrate.

Researchers at the Hong Kong University of Science and Technology (HKUST) have recently realized a series of GaN-based complementary logic ICs. Their paper, published in Nature Electronics, could have important implications for the development of new types of electronics.

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Mott Insulator Exhibits a Sharp Response to Electron Injection In a finding that will give theorists plenty to ponder, an all-RIKEN team has observed an unexpected response in an exotic material known as a Mott insulator when they injected electrons into it. This observation promises to give physicists new insights into such materials, which are closely related to high-temperature superconductors.

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Astronomers may have captured the best view yet of matter colliding with the surface of a young star, findings that may shed light on what the sun looked like in its youth.

Newborn stars are surrounded by a disk of gas and dust from which planets, asteroids, comets and moons are born. The star’s magnetic field connects the star with this protoplanetary disk, “funneling material from the disk onto the star,” study lead author Catherine Espaillat, an astrophysicist at Boston University, told Space.com.

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The Research Brief is a short take about interesting academic work.

The big idea

Many small animals grow their teeth, claws and other “tools” out of materials that are filled with zinc, bromine and manganese, reaching up to 20% of the material’s weight. My colleagues and I call these “heavy element biomaterials,” and in a new paper, we suggest that these materials make it possible for animals to grow scalpel-sharp and precisely shaped tools that are resistant to breaking, deformation and wear.

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New material maintains borophene ’s electronic properties, offers new advantages.

For the first time, Northwestern University engineers have created a double layer of atomically flat borophene, a feat that defies the natural tendency of boron to form non-planar clusters beyond the single-atomic-layer limit.

Although known for its promising electronic properties, borophene — a single-atom.

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Baricitinib is an oral selective Janus kinase 1/2 inhibitor with known anti-inflammatory properties. This study evaluates the efficacy and safety of baricitinib in combination with standard of care for the treatment of hospitalised adults with COVID-19.

In this phase 3 double-blind, randomised, placebo-controlled trial, participants were enrolled from 101 centres across 12 countries in Asia, Europe, North America, and South America. Hospitalised adults with COVID-19 receiving standard of care were randomly assigned (1:1) to receive once-daily baricitinib (4 mg) or matched placebo for up to 14 days. Standard of care included systemic corticosteroids, such as dexamethasone, and antivirals, including remdesivir. The composite primary endpoint was the proportion who progressed to high-flow oxygen, non-invasive ventilation, invasive mechanical ventilation, or death by day 28 assessed in the intention-to-treat population. All-cause mortality by day 28 was a key secondary endpoint, and all-cause mortality by day 60 was an exploratory endpoint; both were assessed in the intention-to-treat population. Safety analyses were done in the safety population defined as all randomly allocated participants who received at least one dose of study drug and who were not lost to follow-up before the first post-baseline visit. This study is registered with ClinicalTrials-gov, NCT04421027.

Although there was no significant reduction in the frequency of disease progression overall, treatment with baricitinib in addition to standard of care (including dexamethasone) had a similar safety profile to that of standard of care alone, and was associated with reduced mortality in hospitalised adults with COVID-19.

Eli Lilly and Company.

Continue reading “Efficacy and safety of baricitinib for the treatment of hospitalised adults with COVID-19 (COV-BARRIER): a randomised, double-blind, parallel-group, placebo-controlled phase 3 trial” | >

I believe the transduction theory has a great deal to offer in our scientific study of the mind–brain relationship. It is, of course, a dualist theory. It provides a framework for understanding the close link between brain states and mental states, yet at the same time, it explains mental states in a way that does not invoke nonsensical materialist metaphysics.

A successful understanding of the mind–brain relationship will necessarily involve understanding the brain as a transduction device in one way or another. Such an understanding could prove enormously fruitful and can help us move beyond the current materialist framework in which neuroscience is practiced, which has has held us so far back in our understanding of the mind and the brain. The brain is obviously material but it is just as obvious that the mind has immaterial abilities.

We accept that the ear is a transducer for sound to hearing and the eye is a transducer for light to vision. It is reasonable to infer that the brain is a transducer for thought to body. Transduction theory is a plausible approach to understanding the connection between the mind and the brain. It should be taken seriously by neuroscientists and philosophers of the mind.

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A team of researchers from Australia, Canada and the U.S. has found that female octopuses sometimes throw silt at males who are attempting to mate with them. The group has written a paper describing their observations and has posted it on the bioRxiv preprint server.

Back in 2,015 members of the research team recorded instances of octopuses throwing things at other octopuses. At the time, it was not clear if the other octopuses were being intentionally targeted or if it was accidental. To find out, they went back to the same site in Jervis Bay, off the coast of Australia, a site where large numbers of Sydney octopuses live.

In making more and studying them carefully, the researchers were able to see that the female octopuses engaged in multiple types of object-throwing. In most instances, throwing material such as silt or even shells was simply a means of moving material that was in the way or when building a nest. Less often, they saw what were clearly attempts by to hurl material at a nearby male—usually, one trying to mate with her.

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