Culture

Lithium-ion batteries have made possible the lightweight electronic devices whose portability we now take for granted, as well as the rapid expansion of electric vehicle production. But researchers around the world are continuing to push limits to achieve ever-greater energy densities -- the amount of energy that can be stored in a given mass of material -- in order to improve the performance of existing devices and potentially enable new applications such as long-range drones and robots.

One promising approach is the use of metal electrodes in place of the conventional graphite, with a higher charging voltage in the cathode. Those efforts have been hampered, however, by a variety of unwanted chemical reactions that take place with the electrolyte that separates the electrodes. Now, a team of researchers at MIT and elsewhere has found a novel electrolyte that overcomes these problems and could enable a significant leap in the power-per-weight of next-generation batteries, without sacrificing the cycle life.

The research is reported in the journal Nature Energy in a paper by MIT professors Ju Li, Yang Shao-Horn, and Jeremiah Johnson, postdoc Weijiang Xue, and 19 others at MIT, two national laboratories, and elsewhere. The researchers say the finding could make it possible for lithium-ion batteries, which now typically can store about 260 watt-hours per kilogram, to store about 420 watt-hours per kilogram. That would translate into longer ranges for electric cars and longer-lasting changes on portable devices.

The basic raw materials for this electrolyte are inexpensive (though one of the intermediate compounds is still costly because it's in limited use), and the process to make it is simple. So, this advance could be implemented relatively quickly, the researchers say.

The electrolyte itself is not new, explains Johnson, a professor of chemistry. It was developed a few years ago by some members of this research team, but for a different application. It was part of an effort to develop lithium-air batteries, which are seen as the ultimate long-term solution for maximizing battery energy density. But there are many obstacles still facing the development of such batteries, and that technology may still be years away. In the meantime, applying that electrolyte to lithium-ion batteries with metal electrodes turns out to be something that can be achieved much more quickly.

The new application of this electrode material was found "somewhat serendipitously," after it had initially been developed a few years ago by Shao-Horn, Johnson, and others, in a collaborative venture aimed at lithium-air battery development.

"There's still really nothing that allows a good rechargeable lithium-air battery," Johnson says. However, "we designed these organic molecules that we hoped might confer stability, compared to the existing liquid electrolytes that are used." They developed three different sulfonamide-based formulations, which they found were quite resistant to oxidation and other degradation effects. Then, working with Li's group, postdoc Xue decided to try this material with more standard cathodes instead.

The type of battery electrode they have now used with this electrolyte, a nickel oxide containing some cobalt and manganese, "is the workhorse of today's electric vehicle industry," says Li, who is a professor of nuclear science and engineering and materials science and engineering.

Because the electrode material expands and contracts anisotropically as it gets charged and discharged, this can lead to cracking and a breakdown in performance when used with conventional electrolytes. But in experiments in collaboration with Brookhaven National Laboratory, the researchers found that using the new electrolyte drastically reduced these stress-corrosion cracking degradations.

The problem was that the metal atoms in the alloy tended to dissolve into the liquid electrolyte, losing mass and leading to cracking of the metal. By contrast, the new electrolyte is extremely resistant to such dissolution. Looking at the data from the Brookhaven tests, Li says, it was "sort of shocking to see that, if you just change the electrolyte, then all these cracks are gone." They found that the morphology of the electrolyte material is much more robust, and the transition metals "just don't have as much solubility" in these new electrolytes.

That was a surprising combination, he says, because the material still readily allows lithium ions to pass through -- the essential mechanism by which batteries get charged and discharged -- while blocking the other cations, known as transition metals, from entering. The accumulation of unwanted compounds on the electrode surface after many charging-discharging cycles was reduced more than tenfold compared to the standard electrolyte.

"The electrolyte is chemically resistant against oxidation of high-energy nickel-rich materials, preventing particle fracture and stabilizing the positive electrode during cycling," says Shao-Horn, a professor of mechanical engineering and materials science and engineering. "The electrolyte also enables stable and reversible stripping and plating of lithium metal, an important step toward enabling rechargeable lithium-metal batteries with energy two times that of the state-the-art lithium-ion batteries. This finding will catalyze further electrolyte search and designs of liquid electrolytes for lithium-metal batteries rivaling those with solid state electrolytes."

The next step is to scale the production to make it affordable. "We make it in one very easy reaction from readily available commercial starting materials," Johnson says. Right now, the precursor compound used to synthesize the electrolyte is expensive, but he says, "I think if we can show the world that this is a great electrolyte for consumer electronics, the motivation to further scale up will help to drive the price down."

Because this is essentially a "drop in" replacement for an existing electrolyte and doesn't require redesign of the entire battery system, Li says, it could be implemented quickly and could be commercialized within a couple of years. "There's no expensive elements, it's just carbon and fluorine. So it's not limited by resources, it's just the process," he says.

Researchers from Queen Mary University of London have developed a machine learning algorithm that ranks drugs based on their efficacy in reducing cancer cell growth. The approach may have the potential to advance personalised therapies in the future by allowing oncologists to select the best drugs to treat individual cancer patients.

The method, named Drug Ranking Using Machine Learning (DRUML), was published today in Nature Communications and is based on machine learning analysis of data derived from the study of proteins expressed in cancer cells. Having been trained on the responses of these cells to over 400 drugs, DRUML predicts the best drug to treat a given cancer model.

Speaking of the new method, Professor Pedro Cutillas from Queen Mary University of London, who led the study, said: "DRUML predicted drug efficacy in several cancer models and from data obtained from different laboratories and in a clinical dataset. These are exciting results because previous machine learning methods have failed to accurately predict drug responses in verification datasets, and they demonstrate the robustness and wide applicability of our method."

The research was funded by The Alan Turing Institute, Medical Research Council, Barts Charity and Cancer Research UK.

How does DRUML work?

The team used datasets derived from proteomics (the study of proteins within cells) and phosphoproteomics (the study of how these proteins are modified) analyses of 48 leukaemia, oesophagus and liver cancer cell lines as the input for DRUML to build models that may be applied to leukaemia and solid tumours.

By training the models using the responses of these cells to 412 cancer drugs listed in drug response repositories, DRUML was able to produce ordered lists based on the effectiveness of the drugs to reduce cancer cell growth. The team then verified the predictive accuracy of the models using data obtained from 12 other laboratories and a clinical dataset of 36 primary acute myeloid leukaemia samples.

Importantly, as new drugs are developed moving forwards, DRUML could be retrained to capture all clinically relevant cancer drugs.

Machine learning and personalised medicine

Cancers of the same type exhibit great variation in their genetic makeup and characteristics from patient to patient. In the clinic, this variation translates to patients having different responses to therapy. To address this issue, the field of personalised medicine aims to combine genetic insights with other clinical and diagnostic information to identify patterns that can allow clinicians to predict patient responses to therapies and select the most effective interventions.

The application of artificial intelligence and machine learning to biomedicine promises to aid personalised medicine and transform how cancers are diagnosed and treated in the future. This study represents a significant advancement in artificial intelligence in biomedical research, and demonstrates that machine learning using proteomics and phosphoproteomics data may be an effective way of selecting the best drug to treat different cancer models.

Many psychiatric disorders have genetic causes, but the exact mechanism of how genes influence higher brain function remains a mystery. A new study provides a map linking the genetic signature of functions across the human brain, a tool that may provide new targets for future treatments.

Led by Bratislav Misic, a researcher at The Neuro (Montreal Neurological Institute-Hospital) of McGill University, a group of scientists performed machine learning analysis of two Open Science datasets: the gene expression atlas from the Allen Human Brain Atlas and the functional association map from Neurosynth. This allowed them to find associations between gene expression patterns and functional brain tasks such as memory, attention, and mood.

Interestingly, the team found a clear genetic signal that separated cognitive processes, like attention, from more affective processes, like fear. This separation can be traced to gene expression in specific cell types and molecular pathways, offering key insights for future research into psychiatric disorders. Cognition, for example, was linked more to the gene signatures of inhibitory or excitatory neurons. Affective processes, however, were linked to support cells such as microglia and astrocytes, supporting a theory that inflammation of these cells is a risk factor in mental illness. The genetic signature related to affect was centred on a brain region called the anterior cingulate cortex, which has been shown to be vulnerable in mental illness.

Published in the journal Nature Human Behaviour on March 25, 2021, this study draws a direct link between gene expression and higher brain function, by mapping gene signatures to functional processes across the human brain.

"In this work we found molecular signatures of different psychological processes," says Misic. "This is exciting because it provides a first step to understand how human thoughts and emotions arise from specific genes, biological pathways and cell types."

Pregnant women who consumed the caffeine equivalent of as little as half a cup of coffee a day on average had slightly smaller babies than pregnant women who did not consume caffeinated beverages, according to a study by researchers at the National Institutes of Health. The researchers found corresponding reductions in size and lean body mass for infants whose mothers consumed below the 200 milligrams of caffeine per day--about two cups of coffee--believed to increase risks to the fetus. Smaller birth size can place infants at higher risk of obesity, heart disease and diabetes later in life.

The researchers were led by Katherine L. Grantz, M.D., M.S., of the Division of Intramural Population Health Research at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development. The study appears in JAMA Network Open.

"Until we learn more, our results suggest it might be prudent to limit or forego caffeine-containing beverages during pregnancy," Dr. Grantz said. "It's also a good idea for women to consult their physicians about caffeine consumption during pregnancy."

Previous studies have linked high caffeine consumption (more than 200 milligrams of caffeine per day) during pregnancy to infants being small for their gestational age (stage of pregnancy) or at risk for intrauterine growth restriction--being in the lowest 10th percentile for infants of the same gestational age. However, studies on moderate daily caffeine consumption (200 milligrams or less) during pregnancy have produced mixed results. Some have found similar elevated risks for low birth weight and other poor birth outcomes, while others have found no such links. The current study authors noted that many of the earlier studies did not account for other factors that could influence infant birth size, such as variation in caffeine content of different beverages and maternal smoking during pregnancy.

For their study, the authors analyzed data on more than 2,000 racially and ethnically diverse women at 12 clinical sites who were enrolled from 8 to 13 weeks of pregnancy. The women were non-smokers and did not have any health problems before pregnancy. From weeks 10 to 13 of pregnancy, the women provided a blood sample that was later analyzed for caffeine and paraxanthine, a compound produced when caffeine is broken down in the body. The women also reported their daily consumption of caffeinated beverages (coffee, tea, soda and energy drinks) for the past week--once when they enrolled and periodically throughout their pregnancies.

Compared to infants born to women with no or minimal blood levels of caffeine, infants born to women who had the highest blood levels of caffeine at enrollment were an average of 84 grams lighter at birth (about 3 ounces), were .44 centimeters shorter (about .17 inches), and had head circumferences .28 centimeters smaller (about .11 inches).

Based on the women's own estimates of the beverages they drank, women who consumed about 50 milligrams of caffeine a day (equivalent to a half cup of coffee) had infants 66 grams (about 2.3 ounces) lighter than infants born to non-caffeine consumers. Similarly, infants born to the caffeine consumers also had thigh circumferences .32 centimeters smaller (about .13 inches).

The researchers noted that caffeine is believed to cause blood vessels in the uterus and placenta to constrict, which could reduce the blood supply to the fetus and inhibit growth. Similarly, researchers believe caffeine could potentially disrupt fetal stress hormones, putting infants at risk for rapid weight gain after birth and for later life obesity, heart disease and diabetes.

The authors concluded that their findings suggest that even moderate caffeine consumption may be associated with decreased growth of the fetus.

An international team of scientists has found evidence that SARS-CoV-2, the virus that causes COVID-19, infects cells in the mouth. While it's well known that the upper airways and lungs are primary sites of SARS-CoV-2 infection, there are clues the virus can infect cells in other parts of the body, such as the digestive system, blood vessels, kidneys and, as this new study shows, the mouth. The potential of the virus to infect multiple areas of the body might help explain the wide-ranging symptoms experienced by COVID-19 patients, including oral symptoms such as taste loss, dry mouth and blistering. Moreover, the findings point to the possibility that the mouth plays a role in transmitting SARS-CoV-2 to the lungs or digestive system via saliva laden with virus from infected oral cells. A better understanding of the mouth's involvement could inform strategies to reduce viral transmission within and outside the body. The team was led by researchers at the National Institutes of Health and the University of North Carolina at Chapel Hill.

"Due to NIH's all-hands-on-deck response to the pandemic, researchers at the National Institute of Dental and Craniofacial Research were able to quickly pivot and apply their expertise in oral biology and medicine to answering key questions about COVID-19," said NIDCR Director Rena D'Souza, D.D.S., M.S., Ph.D. "The power of this approach is exemplified by the efforts of this scientific team, who identified a likely role for the mouth in SARS-CoV-2 infection and transmission, a finding that adds to knowledge critical for combatting this disease."

The study, published online March, 25, 2021 in Nature Medicine, was led by Blake M. Warner, D.D.S., Ph.D., M.P.H., assistant clinical investigator and chief of NIDCR's Salivary Disorders Unit, and Kevin M. Byrd, D.D.S., Ph.D., at the time an assistant professor in the Adams School of Dentistry at the University of North Carolina at Chapel Hill. Byrd is now an Anthony R. Volpe Research Scholar at the American Dental Association Science and Research Institute. Ni Huang, Ph.D., of the Wellcome Sanger Institute in Cambridge, U.K., and Paola Perez, Ph.D., of NIDCR, were co-first authors.

Researchers already know that the saliva of people with COVID-19 can contain high levels of SARS-CoV-2, and studies suggest that saliva testing is nearly as reliable as deep nasal swabbing for diagnosing COVID-19. What scientists don't entirely know, however, is where SARS-CoV-2 in the saliva comes from. In people with COVID-19 who have respiratory symptoms, virus in saliva possibly comes in part from nasal drainage or sputum coughed up from the lungs. But according to Warner, that may not explain how the virus gets into the saliva of people who lack those respiratory symptoms.

"Based on data from our laboratories, we suspected at least some of the virus in saliva could be coming from infected tissues in the mouth itself," Warner said.

To explore this possibility, the researchers surveyed oral tissues from healthy people to identify mouth regions susceptible to SARS-CoV-2 infection. Vulnerable cells contain RNA instructions for making "entry proteins" that the virus needs to get into cells. RNA for two key entry proteins--known as the ACE2 receptor and the TMPRSS2 enzyme--was found in certain cells of the salivary glands and tissues lining the oral cavity. In a small portion of salivary gland and gingival (gum) cells, RNA for both ACE2 and TMPRSS2 was expressed in the same cells. This indicated increased vulnerability because the virus is thought to need both entry proteins to gain access to cells.

"The expression levels of the entry factors are similar to those in regions known to be susceptible to SARS-CoV-2 infection, such as the tissue lining the nasal passages of the upper airway," Warner said.

Once the researchers had confirmed that parts of the mouth are susceptible to SARS-CoV-2, they looked for evidence of infection in oral tissue samples from people with COVID-19. In samples collected at NIH from COVID-19 patients who had died, SARS-CoV-2 RNA was present in just over half of the salivary glands examined. In salivary gland tissue from one of the people who had died, as well as from a living person with acute COVID-19, the scientists detected specific sequences of viral RNA that indicated cells were actively making new copies of the virus--further bolstering the evidence for infection.

Once the team had found evidence of oral tissue infection, they wondered whether those tissues could be a source of the virus in saliva. This appeared to be the case. In people with mild or asymptomatic COVID-19, cells shed from the mouth into saliva were found to contain SARS-CoV-2 RNA, as well as RNA for the entry proteins.

To determine if virus in saliva is infectious, the researchers exposed saliva from eight people with asymptomatic COVID-19 to healthy cells grown in a dish. Saliva from two of the volunteers led to infection of the healthy cells, raising the possibility that even people without symptoms might transmit infectious SARS-CoV-2 to others through saliva.

Finally, to explore the relationship between oral symptoms and virus in saliva, the team collected saliva from a separate group of 35 NIH volunteers with mild or asymptomatic COVID-19. Of the 27 people who experienced symptoms, those with virus in their saliva were more likely to report loss of taste and smell, suggesting that oral infection might underlie oral symptoms of COVID-19.

Taken together, the researchers said, the study's findings suggest that the mouth, via infected oral cells, plays a bigger role in SARS-CoV-2 infection than previously thought.

"When infected saliva is swallowed or tiny particles of it are inhaled, we think it can potentially transmit SARS-CoV-2 further into our throats, our lungs, or even our guts," said Byrd.

More research will be needed to confirm the findings in a larger group of people and to determine the exact nature of the mouth's involvement in SARS-CoV-2 infection and transmission within and outside the body.

"By revealing a potentially underappreciated role for the oral cavity in SARS-CoV-2 infection, our study could open up new investigative avenues leading to a better understanding of the course of infection and disease. Such information could also inform interventions to combat the virus and alleviate oral symptoms of COVID-19," Warner said.

Smoking cigarettes causes 480,000 premature deaths each year in the United States, due mainly to a two-fold risk of cardiovascular disease and a 20-fold risk of lung cancer. Although smoking rates have declined dramatically, there are currently 35 million smokers in the U.S.

In a commentary published in the Ochsner Medical Journal, Charles H. Hennekens, M.D., Dr.PH, senior author, the First Sir Richard Doll Professor, and senior academic advisor in the Schmidt College of Medicine at Florida Atlantic University, and colleagues, highlight how failure to institute smoking cessation in hospitalized patients is a missed opportunity to avoid many premature deaths.

Each year in the U.S., approximately 30 million hospitalizations occur in individuals 18 and older. Of these, more than 7 million are current cigarette smokers whose average hospital stay is several days. The authors comment that starting smoking cessation therapy during hospitalization and maintaining high adherence post-discharge can markedly improve permanent quit rates in these patients with minimal to no side effects. Smoking cessation therapy also should include long-term counseling and at least 90 days of a prescription drug, in particular, varenicline, which works by blocking the pleasurable sensations of nicotine on the brain.

"Providing multifactorial intensive counseling interventions during and after hospitalization and initiating and maintaining adherence to drug therapy are all independent predictors of permanent smoking cessation rates," said Hennekens. "All of these efforts have the potential to reduce many premature deaths from cigarette smoking, which remain alarmingly and unnecessarily high in the U.S. and has already become so worldwide."

Quitting smoking reduces the risk of dying from cardiovascular disease beginning with a matter of months reaching that of lifelong non-smokers within a few years, even among older adults. In contrast, reductions in mortality risk from lung cancer only begin to appear several years after quitting, and even by 10 years, the risk is reduced to only approximately midway between continuing smokers and lifelong smokers. This is because the risks of cardiovascular disease relate to the numbers of cigarettes currently smoked and the risks of cancer to the duration of the habit.

The authors dedicated this manuscript to the memory of the late Edward D. Frohlich, M.D., Ph.D., who was the Alton Ochsner Distinguished Scientist at the Ochsner Clinic Foundation and a staff member of the Ochsner Clinic. The authors refer to Frohlich as a "great man and a good man" who was a valued mentor, colleague and friend. As a member of the Ochsner family for more than 40 years, Frohlich's outstanding contributions helped to propel the Ochsner Clinic to a premier national and international research institution.

In recognition of his seminal discovery research on the hazards of cigarette smoking, Hennekens was the 29th recipient of the prestigious Alton Ochsner Award. Ochsner, a thoracic surgeon, and Michael DeBakey M.D., a future world-renowned cardiovascular surgeon, were early recipients of the award for their case series on smoking and lung cancer in the 1930s. Doll, a British physician, became the foremost epidemiologist of 20th century for pioneering epidemiologic studies, first with Sir Austin Bradford Hill and later with Sir Richard Peto - all who received the Alton Ochsner Award for their contributions to the enormous hazards of cigarette smoking.

From 1995 to 2005, Science Watch ranked Hennekens as the third most widely cited medical researcher in the world and five of the top 20 were his former trainees and/or fellows. In 2012, Science Heroes ranked Hennekens No. 81 in the history of the world for having saved more than 1.1 million lives. In 2016, he was ranked the No. 14 "Top Living Medical Scientist in the World."

Based in part on Hennekens' seminal work on the large clinical and public health hazards of smoking cigarettes, FAU President John Kelly adopted a university-wide tobacco free policy.

An international team led by scientists at the National Institutes of Health and the University of North Carolina at Chapel Hill, has found evidence that SARS-CoV-2, the virus that causes COVID-19, infects cells in the mouth.

While it's well known that the upper airways and lungs are primary sites of SARS-CoV-2 infection, there are clues the virus can infect cells in other parts of the body, such as the digestive system, blood vessels, kidneys and, as this new study shows, the mouth. The potential of the virus to infect multiple areas of the body might help explain the wide-ranging symptoms experienced by COVID-19 patients, including oral symptoms such as taste loss, dry mouth and blistering.

Moreover, the findings point to the possibility that the mouth plays a role in transmitting SARS-CoV-2 to the lungs or digestive system via saliva laden with virus from infected oral cells. A better understanding of the mouth's involvement could inform strategies to reduce viral transmission within and outside the body.

"Due to NIH's all-hands-on-deck response to the pandemic, researchers at the National Institute of Dental and Craniofacial Research were able to quickly pivot and apply their expertise in oral biology and medicine to answering key questions about COVID-19," said NIDCR Director Rena D'Souza, D.D.S., M.S., Ph.D. "The power of this approach is exemplified by the efforts of this scientific team, who identified a likely role for the mouth in SARS-CoV-2 infection and transmission, a finding that adds to knowledge critical for combatting this disease."

The study, published online March 25 in Nature Medicine, was led by Blake M. Warner, D.D.S., Ph.D., M.P.H., assistant clinical investigator and chief of NIDCR's Salivary Disorders Unit, and Kevin M. Byrd, D.D.S., Ph.D., at the time an assistant professor in the Adams School of Dentistry at the University of North Carolina at Chapel Hill. Byrd is now an Anthony R. Volpe Research Scholar at the American Dental Association Science and Research Institute. Ni Huang, Ph.D., of the Wellcome Sanger Institute in Cambridge, U.K., and Paola Perez, Ph.D., of NIDCR, were co-first authors.

Researchers already know that the saliva of people with COVID-19 can contain high levels of SARS-CoV-2, and studies suggest that saliva testing is nearly as reliable as deep nasal swabbing for diagnosing COVID-19. What scientists don't entirely know, however, is where SARS-CoV-2 in the saliva comes from. In people with COVID-19 who have respiratory symptoms, virus in saliva possibly comes in part from nasal drainage or sputum coughed up from the lungs. But according to Warner, that may not explain how the virus gets into the saliva of people who lack those respiratory symptoms. "Based on data from our laboratories, we suspected at least some of the virus in saliva could be coming from infected tissues in the mouth itself," he said.

To explore this possibility, the researchers surveyed oral tissues from healthy people to identify mouth regions susceptible to SARS-CoV-2 infection. Vulnerable cells contain RNA instructions for making "entry proteins" that the virus needs to get into cells. RNA for two key entry proteins--known as the ACE2 receptor and the TMPRSS2 enzyme--was found in certain cells of the salivary glands and tissues lining the oral cavity. In a small portion of salivary gland and gingival (gum) cells, RNA for both ACE2 and TMPRSS2 was expressed in the same cells. This indicated increased vulnerability because the virus is thought to need both entry proteins to gain access to cells.

"The expression levels of the entry factors in are similar to those in regions known to be susceptible to SARS-CoV-2 infection, such as the tissue lining the nasal passages of the upper airway," Warner said.

Once the researchers had confirmed that parts of the mouth are susceptible to SARS-CoV-2, they looked for evidence of infection in oral tissue samples from people with COVID-19. In samples collected at NIH from COVID-19 patients who had died, SARS-CoV-2 RNA was present in just over half of the salivary glands examined. In salivary gland tissue from one of the people who had died, as well as from a living person with acute COVID-19, the scientists detected specific sequences of viral RNA that indicated cells were actively making new copies of the virus--further bolstering the evidence for infection.

Once the team had found evidence of oral tissue infection, they wondered whether those tissues could be a source of the virus in saliva. This appeared to be the case. In people with mild or asymptomatic COVID-19, cells shed from the mouth into saliva were found to contain SARS-CoV-2 RNA, as well as RNA for the entry proteins.

To determine if virus in saliva is infectious, the researchers exposed saliva from eight people with asymptomatic COVID-19 to healthy cells grown in a dish. Saliva from two of the volunteers led to infection of the healthy cells, raising the possibility that even people without symptoms might transmit infectious SARS-CoV-2 to others through saliva.

Finally, to explore the relationship between oral symptoms and virus in saliva, the team collected saliva from a separate group of 35 NIH volunteers with mild or asymptomatic COVID-19. Of the 27 people who experienced symptoms, those with virus in their saliva were more likely to report loss of taste and smell, suggesting that oral infection might underlie oral symptoms of COVID-19.

Taken together, the researchers said, the study's findings suggest that the mouth, via infected oral cells, plays a bigger role in SARS-CoV-2 infection than previously thought. "When infected saliva is swallowed or tiny particles of it are inhaled, we think it can potentially transmit SARS-CoV-2 further into our throats, our lungs, or even our guts," said Byrd.

More research will be needed to confirm the findings in a larger group of people and to determine the exact nature of the mouth's involvement in SARS-CoV-2 infection and transmission within and outside the body.

"By revealing a potentially underappreciated role for the oral cavity in SARS-CoV-2 infection, our study could open up new investigative avenues leading to a better understanding of the course of infection and disease. Such information could also inform interventions to combat the virus and alleviate oral symptoms of COVID-19," Warner said.

LA JOLLA--(March 25, 2021) The brush of an insect's wing is enough to trigger a Venus flytrap to snap shut, but the biology of how these plants sense and respond to touch is still poorly understood, especially at the molecular level. Now, a new study by Salk and Scripps Research scientists identifies what appears to be a key protein involved in touch sensitivity for flytraps and other carnivorous plants.

The findings, published March 16, 2021, in the journal eLife, help explain a critical process that has long puzzled botanists. This could help scientists better understand how plants of all kinds sense and respond to mechanical stimulation, and could also have a potential application in medical therapies that mechanically stimulate human cells such as neurons.

"We know that plants sense touch," says co-corresponding author Joanne Chory, director of Salk's Plant Molecular and Cellular Biology Laboratory and holder of the Howard H. and Maryam R. Newman Chair in Plant Biology. "The Venus flytrap, which has a very fast response to touch, provides an opportunity to study a sensory modality that historically has been poorly understood."

Scientists have long been fascinated by Venus flytraps and carnivorous plants; Charles Darwin devoted an entire book to them. But while previous studies have looked at the structural mechanism of their bizarre leaves, not much is known about how they work at the cellular level. That's partly because flytraps are challenging to study. They're extremely slow to grow, and the flytrap genome had not been sequenced until recently, opening the door for deeper genetic research.

"Because they're so unusual, people have been interested in these plants for hundreds of years, so there's quite a bit known about them at the gross, macroscopic level, but the molecular details have been hard to tease out," says Carl Procko, a staff scientist in Salk's Plant Molecular and Cellular Biology Laboratory.

In the new study, the authors grew cloned flytraps from cuttings to get plants that were genetically identical. Then they carefully cut thousands of microscopic, touch-sensitive trigger hairs from these plants and used sequencing technology to identify which proteins were most abundant in the hairs.

Based on previous research, they knew that the proteins involved in sensing touch were likely to have the capability of moving an electrical current across the cell. Sure enough, this type of protein was the second most common type found in the hairs. The scientists named the new protein FLYCATCHER1. To test the protein, colleagues at Scripps Research put it into mammalian cells. The cells responded by producing an electrical current when touched, proving that the protein is sensitive to mechanical stimuli.

The team found the same protein in the tentacles of the sundew, a carnivorous plant that's a close relative of the Venus flytrap. In the sundew, these sticky tentacles sense the movement of a struggling insect, stimulating the leaf to curl up and trap its prey.

"These findings are further evidence that the FLYCATCHER1 protein plays a critical role in the trigger hairs of the Venus flytrap and the mechanisms of the plant that sense and respond to touch," says Chory.

As a next step, the study authors want to do a "knockout" test and grow genetically modified flytraps with the protein missing. If these flytraps are unable to sense touch, it will prove conclusively that the FLYCATCHER1 protein is responsible.

A multi-institutional collaboration has revealed that α-solanine, a toxic compound found in potato plants, is a divergent of the bitter-tasting α-tomatine, which is found in tomato plants. The research group included Associate Professor MIZUTANI Masaharu and Researcher AKIYAMA Ryota et al. of Kobe University's Graduate School of Agricultural Science, Assistant Professor WATANABE Bunta of Kyoto University's Institute for Chemical Research, Senior Research Scientist UMEMOTO Naoyuki of the RIKEN Center for Sustainable Resource Science, and Professor MURANAKA Toshiya of Osaka University's Graduate School of Engineering.

It is hoped that these research results can be used in potato breeding as a basis for suppressing the synthetization of poisonous compounds.

These research results were published in the international academic journal 'Nature Communications' on February 26.

Main Points

α-solanine is a toxic steroidal glycoalkaloid (SGA) (*1) found in potatoes.

Tomato's α-tomatine is astringent-tasting SGA that accumulates inside unripe fruits.

Based on their chemical structures, SGAs can be divided into two general classes, solanidanes (*2, e.g.α-solanine) and spirosolanes (*3, e.g. α-tomatine).

The research group revealed that the toxic α-solanine in potatoes is biosynthesized from spirosolane.

They discovered that the dioxygenase DPS (*4) is the key enzyme for this catalytic conversion.

It was also revealed that the α-solanine biosynthesis pathway in potatoes diverged from the spirosolane biosynthesis pathway due to the evolution of DPS.

Research Background

α-solanine is a type of toxic steroidal glycoalkaloid (SGA), which accumulates in the green skin on potato tubers (*5) and in tuber sprouts. SGA is not only found in potatoes but also in other plants of the Solanaceae family, including crops like tomatoes and eggplants. These substances are poisonous to many living things and serve as one of the plants' natural defenses. Low concentrations of SGA in potatoes cause a bitter taste and larger amounts can cause food poisoning. For this reason, biosynthesis research has been conducted with the aim of controlling the accumulation of SGA in potatoes.

Based on their skeletal chemical structures, SGAs can be divided into two general classes, solanidanes and spirosolanes (Figure 1). The potato toxinα-solanine is an example of a solanidane, whereas α-tomatine, which accumulates inside unripe tomatoes, is a spirosolane. It is known that both classes of SGA are biosynthesized from cholesterol. Up until now, several genes that encode the catalytic enzymes in SGA biosynthesis have been discovered and potato and tomato plants share these enzymes in the common pathway of SGA biosynthesis. However, the steps and enzymes involved in the metabolic branch point between solanidane- skeleton and spirosolane-skeleton formation remains an unsolved mystery.

This research group showed that the potato toxinα-solanine is biosynthesized from spirosolane. In a world first, they discovered that the dioxygenase DPS is the key to this conversion.

Research Findings

Potatoes contain the toxic solanidanes α-solanine and α-chaconine. The research group investigated theα-solanine biosynthesis pathway in potato plants. Using genome editing, they disrupted the biosynthetic enzyme gene in potato so that it was unable to produceα-solanine. Feeding α-tomatine (a spirosolane found in tomatoes) to the disruptant resulted in a metabolic conversion to the corresponding solanidane compound. In addition, it was found that this metabolic alteration could be suppressed with a 2-oxoglutarate dependent dioxygenase inhibitor, revealing that a dioxygenase is responsible for the oxidation reaction that synthesizes solanidanes from spirosolanes.

The researchers singled out a 2-oxoglutarate dependent dioxygenase (DPS) gene that was expressed in potato during α-solanine synthesis. To investigate this further, the researchers generated modified plants in which DPS gene expression was suppressed via RNA interference (*7). The solanidane concentrations in these modified potato plants were far lower than in the unmodified group, and spirosolanes accumulated inside the plants in place of solanidanes. Next, the researchers measured the enzymatic activity of DPS by recombining the proteins and expressing them in E. coli. The results revealed the unique catalytic role of DPS in spirosolane's conversion into solanidane (Figure 2). This proved that DPS is the key enzyme responsible for this conversion.

This research revealed that the potato's ability to produce α-solanine came about due to the evolution of DPS, which is responsible for metabolically converting spirosolanes (e.g. α-tomatine) into solanidanes. It is known that tomatoes also have an enzyme for metabolizing spirosolanes. The bitter-tasting α-tomatine is found in unripe tomatoes but is metabolized into the tasteless, non-toxic esculeoside A as the fruits ripen. The catalyst for this reaction is 23DOX (*8), which is also a dioxygenase.

From the relationship between their chromosomal positions and phylogenetic analysis, it was revealed that the α-solanine biosynthase DPS has evolved from the same precursor gene as the non-toxic α-tomatine's catalytic enzyme 23DOX. Thus, it is believed that the evolution of the dioxygenase gene that metabolizes spirosolanes is one of the main drivers of the development of structural and functional variation in SGAs.

Further Developments

Potatoes have been termed a potentially dangerous food because large concentrations of toxic α-solanine can cause food poisoning. It is hoped that these research results can provide a basis for future potato varieties in which the biosynthesis of toxic compounds is suppressed by targeting the DPS gene.

As shown in this research, the evolutionary origins of the structural diversity of SGAs provide clues towards discovering unknown SGA synthesis enzymes involved in biological functions in various plants. Illuminating these functions could pave the way for the molecular breeding of plant varieties that are able to adapt to different stressful environments.

CORVALLIS, Ore. - A novel analysis of encounters between albatross and commercial fishing vessels across the North Pacific Ocean is giving researchers important new understanding about seabird-vessel interactions that could help reduce harmful encounters.

The new research method, which combines location data from GPS-tagged albatross and commercial fishing vessels, allows researchers to accurately identify bird-vessel encounters and better understand bird behavior, environmental conditions and the characteristics that influence these encounters.

"It is hard to conceptualize how often birds encounter vessels in the open ocean, but with this new data, it becomes really apparent," said Rachael Orben, an assistant professor in the Department of Fisheries and Wildlife in Oregon State University's College of Agricultural Sciences and the study's lead author. "Some of these birds are in an environment where they see vessels all the time, while others are in an environment where they rarely encounter vessels."

The findings were just published in the Journal of Applied Ecology. Co-authors include Leigh Torres, an associate professor at OSU's Marine Mammal Institute, and David Kroodsma, director of research and innovation for Global Fishing Watch, a not-for-profit organization dedicated to advancing ocean governance through increased transparency of human activity at sea.

Albatross are large, long-lived seabirds that roam widely over the open ocean. Three albatross species are found in the North Pacific: the black-footed albatross, the Laysan albatross and the short-tailed albatross. All three species are of high conservation concern and the short-tailed albatross is listed as endangered under the Endangered Species Act.

Fishing activity can offer the birds opportunities for foraging, but not without risks, including threat of bycatch. Bycatch is the term for fish, birds or other animals caught unintentionally and includes interactions with fishing vessels and fishing gear.

Researchers have been using biologging, the practice of attaching data recording devices to animals, to track individual bird movements at sea for more than 20 years. But they have not had much access to information about the location of vessels, which is a critical piece to understanding the seabird-fishery interaction puzzle, Torres said.

Torres learned that Global Fishing Watch was processing and making available data from the Automatic Identification System, or AIS, an automatic tracking system that uses transceivers on ships. The data includes information about vessel size, movement, fishing method and more. Access to the data was a "game-changer," she said.

"With their data, you can track individual vessels," Torres said. "You can get precise information about a vessel's location, its size, the type of fishing gear it is using and the flag nation of the ship."

Global Fishing Watch's goals include making commercial fishing on the high seas more transparent to the public, improving fisheries regulation and ensuring sustainability of ocean resources.

"This study represents a new frontier in our ability to understand how fisheries impact marine life," said David Kroodsma, director of research and innovation at Global Fishing Watch. "Vessel tracking data, collected by satellites and processed with machine learning, can be a powerful tool to analyze how biodiversity and fishing vessels interact at sea."

Members of the research team had previously collected albatross tracking data from adult black-footed albatross and Laysan albatross breeding in the Papahānaumokuākea Marine National Monument in the Northwest Hawaiian Islands; Laysan albatross nesting on Oahu, Hawaii; and juvenile short-tailed albatross originating from their colonies in Japan.

The researchers were able to marry data on fishing vessels with tracking data from the GPS-tagged albatross during the same periods to identify and locate where bird-vessel interactions occur throughout the North Pacific Ocean.

When birds are within 30 kilometers of a vessel, the researchers assumed the albatross was aware of the vessel's presence, Orben said. When the bird was within 3 kilometers of the vessel, researchers assumed a close encounter between the two. The research team then modeled the drivers of these close encounters.

"With these models, we can start to understand why birds sometimes do and sometimes don't interact with a fishing vessel," Torres said. "This information can help identify how and when efforts should be made to make sure these interactions don't go wrong for the bird. As we start to identify patterns, we can potentially help mitigate these bycatch events."

Among the researchers' findings:

When birds are in a transit state - where they are traveling directly from one location to another - they are not likely to stop and engage with a vessel. But when they are in a foraging state, they are more likely to stop.

Vessel characteristics, including fishing method and the nation of flag on the vessel did not seem to be factors in whether a bird interacted with a vessel.

In areas where there is a lot of fishing, short-tailed and Laysan albatross associated with fishing vessels more frequently.

Short-tailed albatross were more likely to stay with a vessel for a longer period of time in lighter wind conditions.

"These results indicate that it may be more important to use bycatch mitigation methods from a fishing vessel in low wind conditions," Torres said. "Things like that can help guide efforts to reduce bycatch of seabirds. The best regulations are those that are the least burdensome to fishermen and the most effective."

The analysis framework developed by the researchers could be used to study encounters between fishing vessels and other seabirds or marine mammals. Information gathered through the study of these interactions could help inform fisheries management decisions, as well, the researchers said.

"Our study is really one of the first to look at the fine-scale overlap between fishing vessels and marine animals on the high seas, in international waters," Torres said. "It opens a whole new understanding of the dynamics between animals and vessels. This work can help the fishing community fish better and help these seabirds survive and thrive."

Microswimmers are artificial, self-propelled, microscopic particles. They are capable of directional motion in a solution. The Molecular Nanophotonics Group at Leipzig University has developed special particles that are smaller than one-thirtieth of the diameter of a hair. They can change their direction of motion by heating tiny gold particles on their surface and converting this energy into motion. "However, these miniaturised machines cannot take in and learn information like their living counterparts. To achieve this, we control the microswimmers externally so that they learn to navigate in a virtual environment through what is known as reinforcement learning," said Cichos.

With the help of virtual rewards, the microswimmers find their way through the liquid while repeatedly being thrown off of their path, mainly by Brownian motion. "Our results show that the best swimmer is not the one that is fastest, but rather that there is an optimal speed," said Viktor Holubec, who worked on the project as a fellow of the Alexander von Humboldt Foundation and has now returned to the university in Prague. According to the scientists, linking artificial intelligence and active systems like in these microswimmers is a first small step towards new intelligent microscopic materials that can autonomously perform tasks while also adapting to their new environment. At the same time, they hope that the combination of artificial microswimmers and machine learning methods will provide new insights into the emergence of collective behaviour in biological systems. "Our goal is to develop artificial, smart building blocks that can perceive their environmental influences and actively react to them," said the physicist. Once this method is fully developed and has been applied to other material systems, including biological ones, it could be used, for example, in the development of smart drugs or microscopic robot swarms.

Food scientists from Nanyang Technological University, Singapore (NTU Singapore) have made an antibacterial gel bandage using the discarded husks of the popular tropical fruit, durian.

Known as the "King of Fruits" in Southeast Asia, the durian has a thick husk with spiky thorns which is discarded, while the sweet flesh surrounding the seeds on the inside is considered a delicacy.

By extracting high-quality cellulose from the durian husks and combining it with glycerol - a waste by-product from the biodiesel and soap industry - NTU scientists created a soft gel, similar to silicon sheets, which can be cut into bandages of various shapes and sizes.

They then added the organic molecules produced from baker's yeast known as natural yeast phenolics, making the bandage deadly to bacteria.

Developed by Professor William Chen, the Director of NTU's Food Science and Technology Programme, the innovation was published recently in ACS Sustainable Chemistry & Engineering, a peer-reviewed journal of the American Chemistry Society.

Conventional hydrogel patches are commonly available at pharmacies, usually used to cover wounds from surgery to minimise the formation of excessive scar tissue, resulting in a softer and flatter scar. The patch keeps the skin hydrated instead of drying up when conventional band-aid or gauze bandages are used.

Prof Chen said conventional hydrogel patches on the market are made from synthetic materials such as polymers like polymethacrylate and polyvinylpyrrolidine. Those with antimicrobial properties also use metallic compounds such as silver or copper ions. Such synthetic materials approved for use in biomedical applications are more costly as compared to the new hydrogel made from natural waste materials.

"With the growing threat of antibiotic-resistant superbugs, the world will need multiple alternative ways to prevent infections. An effective way to protect open wounds is with antimicrobial bandages that are biocompatible and safe for prolonged use by humans. This is especially important for diabetic patients suffering from chronic wounds," explained Prof Chen, the Michael Fam Chair Professor in Food Science and Technology at the School of Chemical and Biomedical Engineering.

"By using waste products which are currently discarded in large quantities - durian husks and glycerol - we could turn waste into a valuable biomedical resource that can enhance the speedy recovery of wounds and to reduce chances of infections.

With the husk comprising 60 per cent of the durian it is usually discarded and incinerated, posing an environmental issue. In Singapore, it was reported by Straits Times that 14,300 tonnes[1] of durian (estimated 10 million durians) were imported and consumed in 2017.

Being non-toxic and biodegradable, the organic gel bandage is also expected to have a smaller environmental footprint than conventional synthetic bandages.

Giving an independent comment on this innovation, Associate Professor Andrew Tan, Vice Dean (Faculty) from NTU's Lee Kong Chian School of Medicine, who is an expert in metabolic disorders, said there are existing natural and synthetic hydrogels on the market now, where their usefulness in the healing of some types of wounds are well recognised.

"Hydrogel bandages are known for their non-toxicity, ability to rehydrate the wound bed, and can facilitate autolytic debridement (where the body enzymes and natural fluids act to soften bad tissue and remove it). The innovative and unique part of Prof Chen's current work is the upcycling of the durian rind to obtain cellulose. It's also quite unique given that the thorns of the durian can hurt, but the materials from the rind can heal," Assoc Prof Tan said.

Why antimicrobial wound dressings are needed

Wounds linked to chronic diseases are expected to become a more common health burden, where bacterial infection of skin wounds is a serious risk. The market for wound dressing is estimated to be worth $11.4 billion annually, according to a paper published in the European Polymer Journal (A. Gupta et al, 2019).

The clinical advantage of the new hydrogel bandage is that the natural yeast phenolics embedded will help to prevent the growth of bacteria such as Gram-negative E. coli and Gram-positive S. aureus. and the subsequent formation of biofilms (a layer of slime that can lead to antimicrobial resistance within a bacteria colony).

As a proof of concept, the antimicrobial hydrogels were tested as a wound dressing on animal skin and showed good antimicrobial effects for up to 48 hours.

The new proof-of-concept hydrogel bandage is applied by simply laying it across the wound, just as with existing commercially available silicone gel sheets for wound dressing, the current gold-standard used following cosmetic surgeries to reduce scarring.

Other applications of hydrogels

Organic hydrogels are also useful for wearable, flexible and stretchable electronics, which Prof Chen had demonstrated in a 2019 paper published in Scientific Reports.

Wearable electronics can consist of small sensors that can detect heart rate and physical activities, much like current smart bands. They could aid healthcare workers in monitoring the health of the elderly in remote communities.

To demonstrate the use of organic hydrogels in flexible electronics, a prototype hydrogel that could conduct electrical signals was made with cellulose obtained from Okara - the waste leftover from soybean pulp during the making of soy milk.

"As shown in many of our research papers, fundamental research in food science and technology carries far more interdisciplinary applications in other industries, such as healthcare, biomedical applications and speciality chemicals," Prof Chen added.

"Our innovation is in line with the NTU 2025 strategic plan, where research and innovation are key pillars of focus in tackling some of humanity's greatest challenges. By adopting a waste-to-resource approach and the use of green manufacturing techniques, we have shown that it is possible to reduce consumption of Earth's natural resources, reuse what was thought of as rubbish, and recycle them into valuable products that are useful for mankind."

The team of four NTU researchers took two years to research and publish their findings and is now looking for industry partners who may be keen to take their antibacterial gel bandage to market.

European listed companies in the energy and mining sector provide, to say the least, sparse information on future environmental costs in their annual reports. Researchers believe that stricter guidelines are required as the lack of information may lead to underestimation of environmental liabilities, resulting in that future generations may have to bear the burden of cleanup costs.

"I believe that the future environmental liabilities such as decommissioning costs are often underestimated and few understand the burden these costs might impose on future generations. If, for example, an oil & gas company fails, it costs an incredible amount to clean up after old oil wells and the risk is great that the taxpayers will have to pay the bill. Therefore, it is important that environmental obligations are made visible to investors, lenders and the public so that we can discuss the problem," says Mari Paananen, associate professor of business administration at the School of Business, Economics and Law at the University of Gothenburg.

In fact, as there is no clear claimant for this type of future obligations, there is little demand for information either.

"The International Accounting Standards Board* needs to provide clearer requirements about what information should be included in the annual reports in order to make it possible to assess environmental liabilities. I think that such guidelines would make companies inclined to disclose more information and would also provide, for example, auditors a mandate to demand specific information," says Mari Paananen.

Using a sample of 164 European listed companies active in oil, gas, energy (nuclear power) and mining, Mari Paananen and her research colleagues have analyzed environmental disclosures in annual reports over a twelve-year period. Specifically, the researchers use computerized text analysis, to examine information on environment-related restoration costs in the notes to annual reports. Among other things, they searched for information about the discount rate and estimated time horizon for payments - key information needed to assess the size of environmental liabilities.

"Even though we could see that the disclosure of environmental information in the annual reports has increased over time, companies are, are on average, not very forthcoming with information. Approximately 60 percent of the companies provided information about discount rates and 65 percent disclosed the time horizon for the expected future cash outflow. On the other hand, only just over a third provided information about both," says Mari Paananen.

The researchers also investigated whether the level of disclosure increased when companies faced media exposure focusing on environmental issues or how companies' take responsibility for the environment.

"We clearly saw that if companies were exposed in the media, the environmental information increased and the companies provided more specific disclosure on environmental liabilities in the following annual report. Above all, there was more information if the media used an uncertain or litigious tone," says Mari Paananen.

Bright but disadvantaged students from urban areas are more likely to enter elite UK universities than similar peers from rural communities due to an urban 'escalator effect', according to a new study.

Researchers from the University of Bath analysed data from 800,000 English students commencing university in the years 2008, 2010, 2012, 2014 and 2016.

They found that while in general rural areas had higher overall progression to university than city centres and surrounding areas, when controlling for factors including socio-economic status, age, ethnicity and sex, disadvantaged pupils from rural areas were less likely to progress to one of 27 'top' UK universities.

The authors suggest the difference is due to a 'vortex of influences' including 'social mix effects' in more diverse urban settings, successive urban-centred policy interventions and the targeting of university and third-sector outreach activities to urban areas.

Although the results reaffirmed that social class remains the biggest predictor of progression to a top university, the researchers say the results highlight drawbacks of existing geographic measures used to identify disadvantage, as they do not account for the diverse nature of deprived areas, and therefore universities risk missing disadvantaged students. Instead the use of more sophisticated measures could help universities target under-represented and disadvantaged students more effectively, and the authors call for a co-ordinated strategic approach to ensure that no areas are missed by universities' widening participation programmes.

The paper is published in the British Educational Research Journal.

Jo Davies, who led the research as part of her PhD studies in the Department of Education, said: "There has been a lot of interest and concern about geographic inequalities in education. Our paper shows that whilst social background is still the most important predictor for progressing to an elite university, there may also be further geographic factors compounding access. We believe that the use of Geographic Information System (GIS) mapping methods, as used within our own research, could enable elite universities to target under?represented students more effectively, especially disadvantaged students living in rural areas with otherwise good progression rates."

The research team, from the Department of Education, used data from the Higher Education Statistics Agency (HESA) of 800,000 English students beginning university in the academic years 2008/09, 2010/11, 2012/ 13, 2014/15 and 2016/17.

They were interested in progression to 27 'top' UK universities, comprising the Russell Group plus the Universities of St Andrews, Bath and Strathclyde, comparing rates from each Middle Super Output Area (MSOA) in England. Each MSOA, of which there are 6,791 across England, has a population between 5,000 and 15,000, with a minimum of 2,000 and a maximum of 6,000 households.

By analysing progression to these elite institutions after controlling for a factors including education (state/private school education, tariff point score, number of facilitating subjects studied), socio-economic status, age, ethnicity, sex, distance travelled and academic year, the urban escalator effect emerged.

The research was funded by a University of Bath Research Studentship Award. The University currently funds seven PhD students as part of its programme of research aiming to uncover ways in which participation in higher education can be widened and to ensure that no student who has the ability and desire to go to onto higher education is prevented from doing so because of their background.

Dr Matt Dickson, who leads the overall programme for the University's Institute for Policy Research, said: "This research is a great example of the importance of analysis that goes beyond a descriptive picture to understand the key factors that perpetuate inequalities in higher education access. Rather than a simple rural-urban divide, the reality is much more complex and this has important implications for higher education policy."

These lessons are already being implemented at the University of Bath. For example, alongside its existing programme of Widening Participation initiatives the University recently entered into a partnership with Villiers Park Educational Trust to support students from neglected rural and coastal communities to access top universities, such as Bath, through activities including coaching and mentoring for students.

Prof. ZHAO Jin's research team from University of Science and Technology of China (USTC) has made important progress in the development of Spin-Valley exciton dynamics. The research developed an ab initio nonadiabatic molecular dynamics (NAMD) method based on for the spin-resolved exciton dynamics. The team gained the first clear and complete physical picture of valley exciton dynamics in MoS2 from the perspective of first-principles calculations based on GW plus real-time Bethe-Salpeter equation (GW + rtBSE-NAMD).

It can accurately include many-body effects at the level of first principles and break through the bottleneck of GW+BSE method in time-dependent dynamics. The research results were published in Science Advances.

From investigations on MoS2, the research provides a comprehensive picture of spin-valley exciton dynamics where the electron-phonon (e-ph) scattering, spin-orbit interaction (SOI), and electron-hole (e-h) interactions come into play collectively.

In this work, the team develop an ab initio NAMD method based on GW plus real-time propagation of BSE (GW + rtBSE-NAMD). The SOI is included by using the spinor basis sets, and the e-ph coupling is simulated by combining ab initio MD (AIMD) with real-time BSE. The team used the rigid dielectric function approximation and used GW + rtBSE-NAMD to investigate the spin-valley exciton dynamics in monolayer MoS2.

It is found that the intervalley bright exciton transition induces fast valley depolarization within a few picoseconds, which provide a direct evidence that e-h exchange interaction plays an essential role in the intervalley bright exciton transitions in TMD systems.

The newly developed GW + rtBSE-NAMD method provides a powerful tool to investigate the time- and spin-resolved exciton dynamics.

This method can also be widely applied to other material systems to study important physical problems such as exciton relaxation, lifetime, dissociation, and interaction with defects, opening the door to the field of exciton dynamics in solid materials based on first principles.