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Comment by Dr. Krishna Kumari Challa on October 27, 2022 at 9:13am

Scientists discover exotic quantum state at room temperature

For the first time, physicists have observed novel quantum effects in a topological insulator at room temperature. This breakthrough, published as the cover article of the October issue of Nature Materials, came when  scientists explored a topological material based on the element bismuth.

The scientists have used topological insulators to demonstrate quantum effects for more than a decade, but this experiment is the first time these effects have been observed at room temperature. Typically, inducing and observing quantum states in topological insulators requires temperatures around absolute zero, which is equal to -459 degrees Fahrenheit (or -273 degrees Celsius).

This finding opens up a new range of possibilities for the development of efficient quantum technologies, such as spin-based electronics, which may potentially replace many current electronic systems for higher energy efficiency.

Nana Shumiya et al, Evidence of a room-temperature quantum spin Hall edge state in a higher-order topological insulator, Nature Materials (2022). DOI: 10.1038/s41563-022-01304-3

Comment by Dr. Krishna Kumari Challa on October 27, 2022 at 9:10am

Scientists discover material that can be made like a plastic but conducts like a metal

Scientists have discovered a way to create a material that can be made like a plastic, but conducts electricity more like a metal.

The research, published Oct. 26 in Nature, shows how to make a kind of material in which the molecular fragments are jumbled and disordered, but can still conduct electricity extremely well.

This goes against all of the rules we know about for conductivity. In principle, this opens up the design of a whole new class of materials that conduct electricity, are easy to shape, and are very robust in everyday conditions. 

Conductive materials are absolutely essential if you're making any kind of electronic device, whether it be an iPhone, a solar panel, or a television. By far the oldest and largest group of conductors is the metals: copper, gold, aluminum. Then, about 50 years ago, scientists were able to create conductors made out of organic materials, using a chemical treatment known as "doping," which sprinkles in different atoms or electrons through the material.

This is advantageous because these materials are more flexible and easier to process than traditional metals, but the trouble is they aren't very stable; they can lose their conductivity if exposed to moisture or if the temperature gets too high.

But fundamentally, both of these organic and traditional metallic conductors share a common characteristic. They are made up of straight, closely packed rows of atoms or molecules. This means that electrons can easily flow through the material, much like cars on a highway. In fact, scientists till now thought a material had to have these straight, orderly rows in order to conduct electricity efficiently.

Then some researchers began experimenting with some materials discovered years ago, but largely ignored. They strung nickel atoms like pearls into a string of of molecular beads made of carbon and sulfur, and began testing.

To the scientists' astonishment, the material easily and strongly conducted electricity. What's more, it was very stable. When they heated it, chilled it, exposed it to air and humidity, and even dripped acid and base on it, and nothing happened. That is enormously helpful for a device that has to function in the real world.

But the most striking thing was that the molecular structure of the material was disordered.

They tried to understand how the material can conduct electricity. After tests, simulations, and theoretical work, they think that the material forms layers, like sheets in a lasagna. Even if the sheets rotate sideways, no longer forming a neat lasagna stack, electrons can still move horizontally or vertically—as long as the pieces touch.

The end result is unprecedented for a conductive material.

The discovery suggests a fundamentally new design principle for electronics technology.

John Anderson, Intrinsic glassy-metallic transport in an amorphous coordination polymer, Nature (2022). DOI: 10.1038/s41586-022-05261-4. www.nature.com/articles/s41586-022-05261-4

Comment by Dr. Krishna Kumari Challa on October 26, 2022 at 11:26am

Even better, the treatment did not trigger any abdominal discomfort or changes to bowel habits, which can't be said of current medicines for weight gain like Orlistat.

The current research elaborates on these promising findings by comparing an array of 13 porous silica samples of various widths, absorption potentials, shapes, sizes, and surface chemistries.

These samples were each introduced to a human gastrointestinal model that simulated a fed state after a high-carbohydrate, high-fat meal. The model allowed for half an hour of gastric digestion and an hour of intestinal digestion and absorption.

Fat digestion was monitored by titrating fatty acids from what was absorbed, while starch digestion was monitored by measuring the concentration of sugars absorbed.

The authors say the ideal silica samples were silica microparticles with pore widths between 6 and 10 nanometers. These sizes seemed to inhibit the enzymes examined best.

The pores don't just appear to trap enzymes, either. It's more complicated than that, researchers think.

Some pores which were the optimal size for inhibiting starch digestion, for instance, were too large to optimally trap enzymes associated with fat digestion.

The porous sand particles also seemed to absorb digested and undigested nutrients from the gastrointestinal tract before they could pass into the system's bloodstream.

This could be another way in which the particles counter the input of calories.

Those particles with greater surface areas but smaller pores unable to impact digestive enzymes actually absorbed the most organic matter in models.

Further research on animal models will be needed to replicate these results.

https://www.mdpi.com/1999-4923/14/9/1813/htm

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Comment by Dr. Krishna Kumari Challa on October 26, 2022 at 11:25am

Purified Sand Particles Have Anti-Obesity Effects, Scientists Confirm

Porous particles of silica made from purified sand could one day play a role in attempts to lose weight.

Past clinical trials have already produced promising results, but the actual weight-lowering mechanism behind the potential treatment has been poorly understood.

To sift out the key variables, researchers have now tested a range of silica sizes and shapes in a simulation of the human gut after a heavy meal.

The results support the idea that porous silica can "impede the digestive processes" that are usually triggered by enzymes breaking down fat, cholesterol, starches, and sugars in the stomach and intestines.

What's more, the size of administered nanoparticles seems to determine how much digestive activity is inhibited.

The authors acknowledge that their model is much too simple to perfectly mimic the complexity of the human gut during digestion, but given the ethics surrounding human clinical trials, gut simulations and animal models are closer than researchers might otherwise get.

Unlike other human gut models, this new one accounts for both fat digestion and carbohydrate digestion. The authors also analyzed the degree to which organic matter might be absorbed within the gastrointestinal tract.

It's possible that porous silica triggers a reduction of weight gain in other ways, too, but the new findings provide additional research with a more solid place to start.

In 2014, researchers found mice on high fat diets put on significantly less weight when fed nanoparticles of porous silica (MSPs). Their total body fat percentage was also reduced. Still, that effect seemed to be based on the relative size of the silica particles used. Larger particles were ultimately more effective.

Follow-up studies on mice supported these results. The right size and shape of porous silica particles seemed to determine the power of mouse digestion in the small intestine.

In 2020, the first clinical data on 10 healthy humans with obesity demonstrated that MSPs can reduce blood glucose levels and blood cholesterol levels, both of which are known risk factors for metabolic and cardiovascular complications.

Part 1

Comment by Dr. Krishna Kumari Challa on October 26, 2022 at 9:39am

Hidden 'Oasis of Life' Discovered Deep Under The Ocean in The Maldives

Comment by Dr. Krishna Kumari Challa on October 26, 2022 at 9:19am

Climate change is closing daily temperature gap: Clouds could be th...

Climate change is shrinking the difference between the daily high temperature and the daily low in many parts of the world. The gap between the two, known as the diurnal temperature range (DTR), has a significant effect on growing seasons, crop yields, residential energy consumption and human health issues related to heat stress. But why and where the DTR shrinks with climate change has been something of a mystery.

Comment by Dr. Krishna Kumari Challa on October 26, 2022 at 9:04am

Because hemispherectomies are relatively rare, scientists seldom have access to more than a handful of patients at a time. But the Pitt team found an unexpected silver lining of the COVID-19 pandemic: the normalization of telemedicine services, which made it possible to enroll 40 hemispherectomy patients, an unprecedented number for studies of this kind.

To assess word recognition capacity, researchers presented their participants pairs of words, each differing by only one letter, such as "soap" and "soup" or "tank" and "tack." To test how well the children recognized different faces, scientists showed them pairs of photos of people. Either stimulus appeared on the screen for only a fraction of a second, and the participants had to decide whether the pair of words or the pair of faces were the same or different.

Astoundingly, the single remaining hemisphere supported both of those functions. The capacity for word and face recognition between control subjects and people with hemispherectomies differed, but the differences were less than 10%, and the average accuracy exceeded 80%. In direct comparisons between matching hemispheres in patients and controls, patients' accuracy on both face and word recognition was comparable regardless of the hemisphere removed.

This study showed that  losing half of the brain does not equate to losing half of its functionality. While we can't definitively predict how any given child might be affected by a hemispherectomy, the performance that we see in these patients is encouraging. 

Michael C. Granovetter et al, With childhood hemispherectomy, one hemisphere can support—but is suboptimal for—word and face recognition, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2212936119

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Comment by Dr. Krishna Kumari Challa on October 26, 2022 at 9:03am

Word and face recognition can be adequately supported with half a brain, study finds

A study of brain plasticity and visual perception has found that people who, as children, had undergone surgery removing half of their brain, correctly recognized differences between pairs of words or faces more than 80% of the time. Considering the volume of removed brain tissue, the surprising accuracy highlights the brain's capacity—and its limitations—to rewire itself and adapt to dramatic surgery or traumatic injury.

The findings, published recently in the Proceedings of the National Academy of Sciences (PNAS), is the first-ever attempt to characterize neuroplasticity in humans and understand whether a single brain hemisphere can perform functions typically split between the two sides of the brain.

Neuroplasticity is a process that allows the brain to change its activity and rewire itself, either structurally or functionally, in response to changes in the environment. And even though brain plasticity peaks early in development, our brains continue to change well into adulthood.

As humans age, the two halves of our brains, called hemispheres, become increasingly specialized. Even though this division of labor is not absolute, the two hemispheres adopt distinct chief responsibilities: The left hemisphere matures into the primary place for reading printed words, and the right hemisphere matures into the primary place for recognizing faces.

But neuroplasticity has limitations, and this hemispheric preference becomes more rigid over time. In some cases, adults who develop a brain lesion because of stroke or a tumor might experience a reading impairment or become face blind, depending on whether the left or right hemisphere of the brain is affected.

But what happens when the brain is forced to change and adapt while it is still highly plastic? To answer this question, researchers looked at a special group of patients who had undergone a complete hemispherectomy—or a surgical removal of one hemisphere to control epileptic seizures—during childhood.

Part 1

Comment by Dr. Krishna Kumari Challa on October 26, 2022 at 8:41am

Combined, this electron-hole pair is an electrically neutral quasiparticle called an exciton. A quasiparticle is a particle-like entity that does not count as one of the 17 elementary particles of the standard model of particle physics, but that can still have elementary-particle properties like charge and spin. The exciton quasiparticle can also be described as an exotic atom because it is in effect a hydrogen atom that has had its single positive proton replaced by a single positive hole.

Electron-hole systems have been used to create other phases of matter such as electron-hole plasma and even exciton liquid droplets. The researchers wanted to see if they could make a BEC out of excitons.

Direct observation of an exciton condensate in a three-dimensional semiconductor has been highly sought after since it was first theoretically proposed in 1962. Nobody knew whether quasiparticles could undergo Bose-Einstein condensation in the same way as real particles

 Yusuke Morita et al, Observation of Bose-Einstein condensates of excitons in a bulk semiconductor, Nature Communications (2022). DOI: 10.1038/s41467-022-33103-4

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Comment by Dr. Krishna Kumari Challa on October 26, 2022 at 8:39am

Researchers create first quasiparticle Bose-Einstein condensate

Physicists have created the first Bose-Einstein condensate—the mysterious fifth state of matter—made from quasiparticles, entities that do not count as elementary particles but that can still have elementary-particle properties like charge and spin. For decades, it was unknown whether they could undergo Bose-Einstein condensation in the same way as real particles, and it now appears that they can. The finding is set to have a significant impact on the development of quantum technologies including quantum computing.

Bose-Einstein condensates are sometimes described as the fifth state of matter, alongside solids, liquids, gases and plasmas. Theoretically predicted in the early 20th century, Bose-Einstein condensates, or BECs, were only created in a lab as recently as 1995. They are also perhaps the oddest state of matter, with a great deal about them remaining unknown to science.

BECs occur when a group of atoms is cooled to within billionths of a degree above absolute zero. Researchers commonly use lasers and magnet traps to steadily reduce the temperature of a gas, typically composed of rubidium atoms. At this ultracool temperature, the atoms barely move and begin to exhibit very strange behaviour.

They experience the same quantum state—almost like coherent photons in a laser—and start to clump together, occupying the same volume as one indistinguishable super atom. The collection of atoms essentially behaves as a single particle.

Most BECs are fabricated from dilute gases of ordinary atoms. But until now, a BEC made out of exotic atoms has never been achieved. Exotic atoms are atoms in which one subatomic particle, such as an electron or a proton, is replaced by another subatomic particle that has the same charge. Positronium, for example, is an exotic atom made of an electron and its positively charged anti-particle, a positron. An exciton is another such example. When light hits a semiconductor, the energy is sufficient to excite electrons to jump up from the valence level of an atom to its conduction level. These excited electrons then flow freely in an electric current—in essence transforming light energy into electrical energy. When the negatively charged electron performs this jump, the space left behind, or hole, can be treated as if it were a positively charged particle. The negative electron and positive hole are attracted and thus bound together.

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