Source: Global Science, Science and Technology Daily, China Science News, Xinhua News Agency, etc
A versatile technique for fabricating two-dimensional topological superconductors
Source: Y. Jia/Princeton University topological superconductors are considered promising for low-error-rate quantum computing, but progress in fabricating such materials has been slow. In a recent study published in Physical Review X, researchers have achieved a highly controllable and homogeneous on-chip 2D metallization process that converts a class of atomically thin transition metal dichalcogenides (TMDs) into superconductors, which, combined with topological insulators, has the potential to become a versatile technique for fabricating 2D topological superconductors. The research team had developed technology last year to penetrate metal atoms into thin insulating materials in hopes of fabricating two-dimensional topological superconductors. However, the distance of atomic diffusion is usually only at the nanometer scale, and the diffusion pattern is not uniform. But the researchers found that when a small piece of palladium metal was placed on a single-layer topological insulator material, tungsten telluride, and heated to 200 degrees Celsius, the atoms could move farther distances like a liquid diffusing across a film, and the final penetrating atoms formed a new crystal structure, Pd7WTe2. Researchers have confirmed that the new material is superconductive. From this, they developed a technique that can be highly controlled, and by controlling atomic diffusion, superconductivity can be introduced into two-dimensional topological materials and a superconducting disk or ring of a specific size can be fabricated. The results of this study are highly compatible with existing nanofabrication technologies and provide an avenue for the design and manipulation of superconductivity and topological phases in a class of two-dimensional materials. https://journals.aps.org/prx/abstract/10.1103/PhysRevX.14.021051
Semaglutide, the "miracle drug for weight loss", how to create a feeling of satiety to help lose weight
Glucagon-like peptide-1 (GLP-1) is a hormone responsible for signaling fullness after eating. Recently, there are some new weight loss drugs that belong to GLP-1 analogues, GLP-1 receptor agonists (GLP-1 RAs), such as semaglutide, the "miracle drug for weight loss". Moreover, there is recent evidence that such drugs can affect the user's perception of food and reduce the hypothalamus response to food, thereby effectively treating obesity, but the core mechanism is not clear. Recently, a study published in the journal Science showed that GLP-1 RA acts on neurons in the dorsomedial nucleus of the hypothalamus, thereby triggering a feeling of fullness before eating and preventing overeating. The researchers surveyed the satiety of obese people (with or without GLP-1 RA) at three stages: baseline, before eating, and at the time of eating. The results showed that GLP-1 RA significantly improved satiety at each stage, while the control group experienced a decrease in satiety only before eating. By analyzing human and mouse brains, the researchers discovered neural pathways in the dorsomedial nucleus of the hypothalamus, which interacts with GLP-1 RA to suppress appetite. Calcium imaging results showed that optogenetic regulation of these neurons could induce satiety. This study provides a new idea for the use of GLP-1 RA in the treatment of obesity.
https://www.eurekalert.org/news-releases/1049199
A new way to fight measles
Measles is a highly contagious disease caused by a virus. When the virus encounters a human cell, the virus shows itself as a key part of the fusion with the host cell membrane, and once the fusion process is complete, the host cell dies. In a recent study published in Science, scientists at the Vaccine Innovation Center at the La Jolla Institute of Immunology developed a method for measles that could stop the fusion process, and used cryo-electron microscopy to show in unprecedented detail how it prevented the virus from fusing with cell membranes.
Current vaccines often contain inactivated or pathogenicly weakened measles viruses that primarily produce antibodies against hemagglutinin, a protein that helps the virus attach to cells. However, the team at the Center for Vaccine Innovation wanted to find antibodies against the fusion protein in order to successfully stop the fusion of the virus with the cell membrane. Eventually, they set their sights on an antibody called mAb77, which targets a fusion protein of the measles virus, and designed a fusion protein using a variant of the measles virus found in the brains of people with measles encephalitis. Next, they used a cryo-electron microscope to capture images of the fusion protein binding to the antibody and see how the antibody interacted with the virus. They found that after the antibody binds to the fusion protein, the protein can still be converted to an intermediate state, initiating the fusion reaction, but the antibody is able to prevent the fusion process from complete, thus blocking the viral infection. At present, people with weakened immunity are unable to receive existing vaccines, and the researchers will test the effectiveness and safety of the new method in these patients.
https://www.eurekalert.org/news-releases/1049786
The researchers mapped the neural circuits of Drosophila movement
Source: Tyler Sloan/Quorometrix Studio One of the main functions of the nervous system is to coordinate the movement of the body. To understand how the brain controls adaptive motor behavior, scientists have long tried to decipher the neural circuit maps that control muscle movement. In two recent studies published in Nature, researchers mapped the neural circuits that control muscle movement in fruit flies. One study used automated tools, machine learning, cell type annotation and electron microscopy to identify 14,600 neuronal cell bodies and 46 million synapses in the ventral nerve cord (similar to the spinal cord of a vertebrate) in a female Drosophila. Subsequently, the researchers used deep learning to automatically reconstruct the neuronal anatomy and connections of the entire female Drosophila. Another study mapped the muscles targeted by the motor neurons of the legs and wings of Drosophila. They determined which motor neurons in this female Drosophila nerve cord group were connected to which muscles of the forelegs and wings. Based on this, they mapped a map of the neural circuits that coordinate the movement of the legs and wings of Drosophila during take-off and flight movement initiation. These two studies were the first to map synapses-level neural circuits in arthropods, allowing researchers to propose new theories about the function of neural circuits and disprove some erroneous theories. The researchers hope that future studies can compare more connectomes between different Drosophila individuals.
https://www.nature.com/articles/s41586-024-07389-x
Plants store more carbon than expected, but for a shorter period than expected
Plants are able to absorb carbon dioxide through photosynthesis and convert it into organic matter for storage in the body. However, according to a recent study published in Science, scientists at Imperial College London in the United Kingdom have found that plants, while able to absorb carbon dioxide quickly, may release it back into the atmosphere more quickly and store carbon for less than expected.
Nuclear bomb experiments in the 60s produced large amounts of radioactive carbon (¹⁴C) and entered the carbon cycle of vegetation. Scientists substituting radiocarbon storage data into carbon cycle calculation models found that existing models underestimated radiocarbon accumulation (i.e., net primary productivity, NPP) in vegetation. In comparison, the new estimate is 80 gigagrams per year, while the previous model predicted only 43~76 gigagrams. At the same time, existing models overestimate the storage time of carbon in vegetation, which may be due to underestimating carbon storage in short-lived non-wood tissues. This study suggests that improving theories about how plants grow and interact with ecosystems, and adapting global climate models accordingly, will contribute to a better understanding of how the biosphere mitigates climate change and estimates progress towards the greenhouse effect.
https://phys.org/news/2024-06-carbon-shorter-periods-thought.html
Occupational diseases of senior white-collar workers in ancient Egypt
The dwarf planet Tronis has rare rings
Source: Original paper
The ancient Egyptian scribe was a high-ranking man who was able to write and was engaged in administrative work in ancient Egypt. The wall decorations of ancient Egyptian statues and tombs record the sitting and standing postures of their work. Some of them sit cross-legged for a long time, some prefer to squat or squat, and some stay standing. A recent paper published in Scientific Reports suggests that the repetitive work of ancient Egyptian scribes and the way they sat while working may have contributed to degenerative bone lesions. The researchers analyzed the remains of 69 adult males, 30 of whom were scribes, who were buried between 2700 and 2180 BC at the tomb of Abusir in Egypt. They found that scribes had degenerative joint lesions more often than men in other occupations. The authors believe that the degenerative lesions of the scribes' spine and shoulders may have been due to their long sitting cross-legged, with their heads bent forward, their spine bent, and their arms unsupported; Changes in the knees, hips, and ankles suggest that the scribe may have preferred to sit on his knees or cross-legged with his right leg bent and his knee facing up. Both of these sitting postures correspond to the wall decorations of the statues and tombs. The deterioration of the jaw joint may be due to the scribe chewing on the end of the corduroy stem to form a brush-like head to write, and the degeneration of the thumb may be caused by repeated pinching of the pen. These discoveries provide a deeper understanding of the life of Egyptian scribes in the third millennium BC.
https://www.nature.com/articles/s41598-024-63549-z
Let the robot have special skins
Previously, attaching artificial skin tissue to solid surfaces often required structures such as mini-anchors or hooks, which limited the types of solid surfaces that could be combined with artificial skin and could cause damage to the artificial skin during movement. In a recent paper published in the journal Cell Reports Physical Science, researchers have developed a technology that can attach artificial skin tissue to the complex structure of humanoid robots. The research team mimics the structure of human skin ligaments, using special V-shaped holes on the humanoid robot's face to help the skin adhere better, while using a naturally sticky collagen gel for bonding. Using plasma treatment, the researchers successfully guided the collagen into the robot's delicate pore structure to fit the skin to the surface in question. This design improves the compatibility of the robot's skin with mechanical components while avoiding tearing or peeling. In addition, this biological skin could bring a new set of abilities to the robot, even the ability to repair itself, allowing it to repair minor cuts just like our skin. This technology can even be extended to the cosmetics industry and plastic surgery, where it will be of high value.
https://www.cell.com/cell-reports-physical-science/fulltext/S2666-3864(24)00335-7?
For many city dwellers, the real temperature in the city exceeds the weather forecast
The heaviest wild feed on Earth
Source: Duke University The urban heat island effect refers to the phenomenon of higher temperatures in an area than the surrounding areas due to more buildings, less vegetation and higher population density. Poor areas of American cities tend to be warmer than wealthier areas. Previously, weather information in many parts of the U.S. came from private weather stations set up by citizen scientists, which were taken by the weather stations and shared on a website called Weather Underground. However, a recent study published in Environmental Science and Technology Letters suggests that the heat island effect is likely underestimated by citizen science tools used to measure temperature in these urban areas. The researchers mapped four years of temperature data in North Carolina from the Weather Subsurface website and mapped the distribution of weather stations, and compared them with the median income of each region, they found that there were more weather stations in areas with higher median incomes. And in the poorest and hottest areas of the city, there are very few individual weather stations. Based on this correlation, the researchers validated their method by adjusting the data and comparing it with temperature data from the National Thermal Health Information System (NIHHIS). Adjusted data shows that the average evening temperature estimate for July 2021 was nearly 1°C higher than previously reported in areas with fewer weather stations in Durham, North Carolina. This study provides a statistical method to more accurately estimate and correct for the heat island effect in cities.
https://pubs.acs.org/doi/10.1021/acs.estlett.4c00296
Extreme wildfires have doubled in the last 20 years
In recent years, major wildfire incidents have continued to break historical records and attract global attention. These wildfires have claimed human lives, property, livestock, wildlife and habitats, causing billions of dollars in damage. The corresponding air pollution is thought to have caused thousands of additional deaths. The frequency and intensity of extreme wildfires appear to have doubled in the last 20 years, and six of the most extreme years have occurred since 2017.
To understand whether wildfires are increasing in frequency and/or intensity, the researchers used satellite data from 2003 to 2023 to identify active hotspots and calculated the total intensity of a single fire event, rather than just targeting a single time and place. They found that extremely violent wildfires have more than doubled in frequency and intensity over the past 20 years, and that the six most extreme years have occurred since 2017. They also found that the New Northern Territory and the New Zealand/Oceania were most affected by these extreme events, with the increase in extreme events mainly due to more intense fires in temperate coniferous and boreal coniferous forests, including in North America and Russia, which may be related to the increase in drought in these forests due to climate change in recent years. The findings were published June 24 in Nature Ecology & Evolution.
https://www.nature.com/articles/s41559-024-02452-2
Submarine observatories have discovered the highest-energy neutrinos ever detected
Ultra-high-energy neutrinos (tiny subatomic particles traveling at nearly the speed of light) are only a decade old and are seen as messengers for some high-energy events in the universe, such as the explosion of supermassive black holes in distant galaxies. According to Nature news, on June 18, local time, at the 2024 Neutrino Conference (Neutrino 2024) held in Milan, Italy, researchers said that they detected the most energetic neutrino so far with the help of the Astroparticle Research with Cosmics in the Abyss (ARCA) observatory.
ARCA is a neutrino observatory under construction located on the bottom of the Mediterranean Sea and a larger component of the Cubic Kilometer Neutrino Telescope (KM3NeT). ARCA currently consists of 28 ropes, each 800 meters long, strung with 18 plexiglass sphere detector units that can be used to sense faint photons. The research team hopes to expand the total number of ropes to 230 by 2028. Most of the light sources detected by ARCA are high-energy particles produced by high-energy cosmic ray particles hitting the Earth's atmosphere, as well as high-energy charged particles μ mesons produced by high-energy neutrinos passing through the Earth. More than one-third of the ARCA sensors recorded flashes consistent with the μ passing horizontally through the observatory, which were generated by neutrinos arriving about 1 degree below the horizon. This means that the energy of these neutrinos could be as high as tens of petaelectron volts, making them the highest-energy neutrinos ever detected, the researchers said. The researchers did not disclose the exact direction of the neutrino source and the timing of the observations at the conference, but plan to present these details in a follow-up paper.
https://www.nature.com/articles/d41586-024-02074-5
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