Second Central Asian Dust Conference

German-Uzbek cooperation brings researchers together

LEIBNIZ INSTITUTE FOR TROPOSPHERIC RESEARCH (TROPOS)

 

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VIEW FROM THE STEEP BANK OF THE FORMER ARAL SEA DOWN TO A SHIP GRAVEYARD IN MUYNAK.

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CREDIT: DIETRICH ALTHAUSEN, TROPOS

Nukus/Leipzig. Researchers from 14 countries will meet in Nukus, Uzbekistan, from April 15-22, 2024 for the second Central Asian Dust Conference. The conference is organized in a hybrid format: Of the more than 80 researchers, around 30 will participate online and discuss more than 50 submitted papers. Nukus is the capital of the Autonomous Republic of Karakalpakstan in Uzbekistan, lies south of the former Aral Sea and is frequently affected by intense dust events. The "Central Asian DUst Conference (CADUC-2)" is organized by the Karakalpak State University Nukus, the Hydrometeorology Scientific Research Institute (HMRI) Uzbekistan, the Leibniz Institute for Tropospheric Research (TROPOS) and the Philipps University Marburg. Five years ago, more than 80 researchers also met in the Tajik capital Dushanbe for the first Central Asian Dust Conference CADUC. CADUC-2 continues this tradition. The arid regions in the desert belt of the northern hemisphere extend from the Sahara in western Africa to the Middle East and the deserts of China. Millions of people in these regions suffer from the effects of dust on their health, flora, economy and climate. Nevertheless, for a long time Central Asia was almost a blank spot in global dust research using active remote sensing until the first TROPOS laser measurements began ten years ago in the Central Asian republic of Tajikistan. Since then, the cooperation with Germany has developed very successfully and inspired many researchers.

  

The former port city of Muynak was once located on a peninsula at the southern end of the Aral Sea. Today, the shore is around 80 kilometers away.

In total, dust particles with a mass of around 1500 megatons are released into the atmosphere every year. The Sahara is thought to be the main source with around 1000 megatons. So far, it can only be speculated how much the deserts and steppes of Central Asia contribute to the total amount of mineral dust in the atmosphere, because for a long time there was a lack of measurements in this important region of the dust belt. How long dust remains suspended in the air varies and depends on regional weather conditions and particle size. Large particles have a shorter residence time than small and therefore lighter particles, which can quickly reach high altitudes in the updraft. On average, dust particles remain in the atmosphere for one to two weeks and disperse with the wind.

  

Muynak was once known for its fishing.

Mineral dust plays a major role in the global climate because the dust particles floating in the atmosphere reflect sunlight and dim the sun's rays reaching the ground. In addition to this direct effect, there is also a so-called indirect aerosol effect: the particles act as cloud nuclei and influence cloud formation, which also has an impact on the Earth's radiation budget and can cool or warm depending on the type and height of the clouds. In addition, there are many other effects whose significance has only been slowly understood in recent years: Chemical reactions can take place on the surface of the dust. Trace metals in mineral dust fertilize the ocean and thus drive many biogeochemical processes in the sea. Large dust outbreaks can affect local infrastructure such as photovoltaic systems. Added to this are the effects on people's health, some of whom suffer from severe dust storms: Dust has a negative impact on the respiratory tract and can also transport bacteria and thus diseases.

The silting up of the Aral Sea and the desertification there is considered one of the biggest environmental disasters on the territory of the former Soviet Union.

The content and origin of the contributions at the Central Asian DUst Conference (CADUC-2) in Nukus are as complex as the impact of dust on climate, infrastructure and health. The capital of the Autonomous Republic of Karakalpakstan in Uzbekistan is located on the Amudarya River and is closely linked to the development of the Aral Sea. As more and more water was taken from the tributaries to irrigate the cotton fields from the 1960s onwards, the lake largely dried up. The silting up and desertification is considered one of the biggest environmental disasters in the territory of the former Soviet Union. Dust days are now recorded in Nukus on around 270 days per year. One session is therefore dedicated to research into dust on the Aral Sea. Other topics at the conference include the effects of the dust stirred up in the desert and arid regions, the changes in properties during dust transport in the atmosphere, the consequences for the regions where the dust falls, approaches for early warning systems and success stories in combating sand and dust storms. Tilo Arnhold

More than 80 researchers from 14 countries will meet in April for the second Central Asian Dust Conference in Nukus, Uzbekistan, on the edge of the former Aral Sea.

CREDIT

Dietrich Althausen, TROPOS

 

People who use willpower alone to achieve goals, resist temptation, deemed more trustworthy

Why people are reluctant to use incentives, deterrents, even when they know they work

Peer-Reviewed Publication

AMERICAN PSYCHOLOGICAL ASSOCIATION

People who use willpower to overcome temptations and achieve their goals are perceived as more trustworthy than those who use strategies that involve external incentives or deterrents – such as swear jars or internet-blocking apps – according to research published by the American Psychological Association.

“The knowledge that people can use external commitment strategies to overcome self-control problems has existed in some form for thousands of years. Since at least the time of Homer and Odysseus, the focus has primarily been on the efficacy of these strategies for the person choosing to engage in them,” said lead author Ariella Kristal, PhD, of Columbia University. “This prior work has demonstrated, for example, that Odysseus made the right decision to tie himself to the mast rather than attempting to use willpower to resist the sirens in the moment.”

Known as commitment strategies, these approaches have been shown to improve success for a variety of goals, including smoking cessation, weight loss, academic achievement and saving money, according to Kristal. Despite the benefits of commitment strategies, though, little research has been done on how they affect others’ perceptions of people using them. 

To better understand how people’s use of commitment strategies over willpower affects others’ perceptions of them, Kristal and her co-author, Julian Zlatev, PhD, of Harvard Business School, conducted a series of online experiments involving more than 2,800 participants from the United States.

The research was published in the Journal of Personality and Social Psychology.

In most of the experiments, participants were presented with a hypothetical situation involving individuals who attempted to achieve a goal using willpower or a commitment strategy. In one experiment, they were asked to rate the integrity of hypothetical individuals who used willpower to avoid an unwanted behavior (e.g., eating junk food or drinking alcohol) versus paying $5 every time they engaged in the unwanted behavior. In another scenario, hypothetical individuals either used willpower or an app to avoid distracting websites like Facebook or Instagram.

Overall, individuals who were described as using commitment strategies to achieve their goals were judged to be less trustworthy than those who used willpower alone. 

In two experiments, researchers found that participants were more likely to rate hypothetical users of commitment strategies as less trustworthy, even though the participants recognized the strategies were more effective than willpower alone. In another, participants were less likely to choose an external commitment strategy if they thought others might find out.

“People appear particularly hesitant to adopt commitment strategies when their use will be made public and, while not as high, people’s resistance continues to remain elevated even when the use of strategies will be kept private,” said Kristal. “This occurs despite the fact that people do recognize and acknowledge the benefits of these commitment strategies.”

The researchers believe that the choice to use a commitment strategy signals to others a deficiency in an individual’s character. That is, people believe those who require external aid (as opposed to using just willpower) are more likely to have failed in the past and therefore are less capable of overcoming self-control problems on their own.

“Past failures of self-control can be seen by others as moral failures. Because morality is an important component of integrity in particular, and trustworthiness more broadly, people who rely on commitment strategies may be viewed as less trustworthy than those who simply use willpower,” said Kristal.

These findings have important implications for developing programs and initiatives that rely on external strategies to help people achieve their goals, according to Kristal. By examining the role of interpersonal judgments in self-control strategy choice, we can begin to understand why people may fail to adopt these beneficial strategies and how to better promote effective strategy use.

ARTICLE: “Going beyond the self in self-control: Interpersonal consequences of commitment strategies,” by Ariella Kristal, PhD, Columbia University Business School, and Julian Zlatev, PhD, Harvard Business School. Journal of Personality and Social Psychology, published online April 11, 2024.

CONTACT: Ariella Kristal can be contacted at ask2304@columbia.edu and Julian Zlatev can be contacted at jzlatev@hbs.edu.

The American Psychological Association, in Washington, D.C., is the largest scientific and professional organization representing psychology in the United States. APA’s membership includes over 157,000 researchers, educators, clinicians, consultants and students. Through its divisions in 54 subfields of psychology and affiliations with 60 state, territorial and Canadian provincial associations, APA works to advance the creation, communication and application of psychological knowledge to benefit society and improve people’s lives.

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JOURNAL

Journal of Personality and Social Psychology

DOI

10.1037/pspa0000385 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Going Beyond the “Self” in Self-Control: Interpersonal Consequences of Commitment Strategies

ARTICLE PUBLICATION DATE

11-Apr-2024

 

New study shows effect of socio-economic factors—housing, food, neighborhood—to predict diabetic patients’ risk of heart failure

CASE WESTERN RESERVE UNIVERSITY

 

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SALIL DEO

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CREDIT: CASE WESTERN RESERVE UNIVERSITY

CLEVELAND—A recent study by Case Western Reserve University used national data from U.S. military veterans with diabetes to validate and modify a widely accepted model used to predict the risk of heart failure in diabetic patients.

The model, called the WATCH-DM score, is used to predict the likelihood of heart failure in diabetes patients within five years.

But because it overlooks the influence of social determinants of health‚ such as housing, food and a patient’s neighborhood, the researchers used a social deprivation index (SDI), a multi-component summary score, to adjust the WATCH-DM score. 

The SDI, introduced by the Robert Graham Center, a group of clinical researchers, can quantify the level of disadvantage in particular areas using food, housing, transportation and community conditions. Prior research demonstrated this score is directly proportional to the level of health disparities observed in communities.

The study identified about 1 million U.S. veterans with type 2 diabetes without heart failure treated as outpatients at Veterans Affairs medical sites nationally in 2010.

Researchers used patient zip codes to obtain their SDI, which was then entered into the risk calculator to determine how likely they would be hospitalized for heart failure within five years.   

While the hospitalization rate for heart failure for the whole cohort of more than 1 million patients was 5.39%, this incidence varied from 3% (in the least socially deprived) to 11% (in the most deprived). 

Researchers found that, depending on the patients’ other clinical information, adding the SDI into the risk-prediction model could even double the probability of that patient developing heart failure in the next five years.

The team of investigators then optimized the WATCH-DM score for each SDI group using a statistical correction factor and improved its predictive accuracy across the whole range of the social determinants of health. 

“We found that adding the SDI enhanced the WATCH-DM score’s ability to forecast risk,” said Salil Deo, an associate professor in the Department of Surgery at the Case Western Reserve School of Medicine, who led the study. “These results highlight the necessity of including social determinants of health in any future clinical risk prediction algorithms. This will increase their accuracy, which will benefit patients by improving their health outcomes.”

This calculator is available to the public from their device for free here. 

“We hope our study encourages healthcare providers to adopt a wholistic approach when treating patients in the future,” Deo said. “Understanding and quantifying social inequity is likely the first step we can take toward trying to ensure that it does not affect the health of our patients.” 

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Case Western Reserve University is one of the country's leading private research institutions. Located in Cleveland, we offer a unique combination of forward-thinking educational opportunities in an inspiring cultural setting. Our leading-edge faculty engage in teaching and research in a collaborative, hands-on environment. Our nationally recognized programs include arts and sciences, dental medicine, engineering, law, management, medicine, nursing and social work. About 6,000 undergraduate and 6,300 graduate students comprise our student body. Visit case.edu to see how Case Western Reserve thinks beyond the possible.

 

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METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

 

Genetic underpinnings of environmental stress identified in model plant

HIROSHIMA UNIVERSITY

 

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TRANSCRIPTOME DATA UNDER ABA-RELATED STRESSES WAS ANALYZED USING 216 PAIRS OF ARABIDOPSIS GENE EXPRESSION DATA ACCUMULATED IN PUBLIC DATABASES. GENES WITH VARIABLE EXPRESSION LEVELS COMMON TO FIVE STRESS TREATMENTS (ABA, SALT, DROUGHT, OSMOTIC PRESSURE, AND COLD) WERE IDENTIFIED. 14 GENES WERE UPREGULATED IN ALL STRESS TREATMENTS, AND 8 GENES WERE DOWNREGULATED IN ALL TREATMENTS.

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CREDIT: MITSUO SHINTANI/HIROSHIMA UNIVERSITY

Plants can be temperamental. Even weeds along the side of highways or pushing their way up in the cracks of concrete sidewalks can get stressed out by dehydration, cold, excess salt and more. Researchers at Hiroshima University have identified 14 genes that thale cress — a plant commonly used in genetic investigations since its genome is well documented — express more when responding to five specific stressors, as well as eight genes that the plant suppresses.

They published their results on March 22 in Frontiers in Plant Science. 

“Abiotic stresses — as opposed to biotic stresses like pests or disease — such as drought, salinity and cold negatively affect plant growth and crop productivity. Understanding the molecular mechanisms underlying plant responses to these stressors is essential for stress tolerance in crops,” said corresponding author Hidemasa Bono, professor in the Laboratory of Genome Informatics at Hiroshima University’s Graduate School of Integrated Sciences for Life. Bono is also affiliated with the Laboratory of Bio-DX in the university’s Genome Editing Innovation Center. 

“The plant hormone abscisic acid (ABA) is significantly increased upon abiotic stressors, inducing physiological responses to adapt to stress and regulate gene expression. Although many studies have examined the components of established stress signaling pathways, few have explored other unknown elements.”

To better understand the molecular pathways that allow ABA to increase, the research team analyzed public RNA sequencing data on thale cress, or Arabidopsis thaliana. RNA sequencing is a technique that enables scientists to identify and quantify specific sequences of genetic instructions programmed in an organism’s RNA. This data can reveal how different variables may increase or decrease the expression of certain genes.

Bono and his team specifically focused on five ABA-related stress conditions: ABA, when the hormone is applied directly to the plant; salt, which changes how the plant can use water; dehydration, or how much water the plant has; osmotic, when plant cells swell or shrink inappropriately; and cold.

“The data-driven studies have the advantage of analyzing large and independent datasets, which can lead to the identification of novel targets, distinct from the extensively studied established factors and accelerate the development of stress-tolerant crops,” Bono said.

The researchers performed a meta-analysis of 216 paired datasets, combining those research results and reanalyzing them to identify where data might overlap or reveal previously unknown connections.

The meta-analysis revealed that 14 genes were commonly up-regulated and eight genes were commonly down-regulated across all five ABA-related stress responses investigated. Bono noted that some genes regulated by salt, dehydration and osmotic treatments were not regulated by ABA or cold stress, suggesting that they may be involved in the plant response through a different signaling pathway.

“Our meta-analysis revealed a list of candidate genes with unknown molecular mechanisms in ABA-dependent and ABA-independent stress responses,” Bono said.

“These genes could be valuable resources for selecting genome editing targets and potentially contribute to the discovery of novel stress tolerance mechanisms and pathways in plants. We will continue to develop methods and utilize data from public databases and conduct comparative analysis from various angles to unravel the unknown mechanisms of stress response in plants.”

Co-authors of the study are Mitsuo Shintani with the Graduate School of Integrated Sciences for Life at Hiroshima University and Keita Tamura with the university’s Genome Editing Innovation Center.

The Center of Innovation for Bio-Digital Transformation (BioDX) and the Japan Science and Technology Agency supported this research.

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About Hiroshima University

Since its foundation in 1949, Hiroshima University has striven to become one of the most prominent and comprehensive universities in Japan for the promotion and development of scholarship and education. Consisting of 12 schools for undergraduate level and 4 graduate schools, ranging from natural sciences to humanities and social sciences, the university has grown into one of the most distinguished comprehensive research universities in Japan. English website: https://www.hiroshima-u.ac.jp/en

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JOURNAL

Frontiers in Plant Science

DOI

10.3389/fpls.2024.1343787 

METHOD OF RESEARCH

Meta-analysis

ARTICLE TITLE

Meta-analysis of public RNA sequencing data of abscisic acid-related abiotic stresses in Arabidopsis thaliana

 

Geobiology: new placozoan habitat discovered

LUDWIG-MAXIMILIANS-UNIVERSITÄT MÜNCHEN

Traces of DNA in the stomachs of predatory snails give a team led by LMU geobiologist Gert Wörheide new insights into the ecology of placozoans.

Placozoans are among the simplest animals and occur worldwide in coastal waters. It was previously assumed that the tiny creatures, which measure just a few millimeters, live either on hard surfaces – such as rocks, corals, and mangrove roots – or float in open coastal waters as so-called “swarmer” stages. Through analysis of DNA traces in the stomachs of predatory sea slugs, a team led by LMU geobiologist Professor Gert Wörheide has demonstrated that the animals also live in the seabed sediment, a habitat they were previously thought not to colonize. In addition, they are more genetically diverse than had been known, as the researchers report in the journal Ecology and Evolution.

With their flat, disk-shaped bodies, all placozoans worldwide look strikingly similar. Nevertheless, Wörheide and his team were already able to demonstrate in previous studies that there are huge genetic differences between them. “These differences are comparable with those between humans and mice,” emphasizes the geobiologist.

Due to their diminutive size and inconspicuousness, placozoans are challenging to study in their natural environments. To gain a better insight into the ecology of the animals, the researchers exploited the fact that small shell-less sea slugs from the Rhodopidae family feed on placozoans.

 

Among the undigested meals of sea snails

 “We hoped we could find undigested remains of placozoans in the stomach contents of the snails, which we could then perform molecular analyses on,” recounts Dr. Michael Eitel, lead author of the study. “To this end, we bioinformatically investigated publicly accessible genetic data for the snails for traces of placozoan DNA.”

To the researchers’ surprise, they also identified the DNA of placozoans in the stomachs of snails that live exclusively in seabed sediments – a habitat that all experts had previously ruled out for the very fragile placozoans. “Clearly, however, their presence in sediments is a normal occurrence and could even play a key role in their biology, particularly in their sexual reproduction, about which we have only rudimentary knowledge,” says Eitel.

Furthermore, the scientists discovered an unexpectedly large genetic diversity. In the stomach contents of just two snails, they found five genetically different lineages, of which three had never been described before. In the view of the researchers, this indicates that the diversity of placozoans is much greater than previously assumed. “Our results will have a big impact on our picture of the developmental history of one of the oldest phyla on Earth,” says Wörheide. “At the same time, the major new habitat discovery literally adds another dimension to the ecology of placozoans.”

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JOURNAL

Ecology and Evolution

DOI

10.1002/ece3.11220 

ARTICLE TITLE

Beauty in the beast – Placozoan biodiversity explored through molluscan predator genomics

ARTICLE PUBLICATION DATE

11-Apr-2024

 

UMSOM researchers identify safety of a potential new treatment to manage complications from sickle cell disease

Treatment for lung condition could help patients with sickle cell disease control complications from hypertension and kidney damage

UNIVERSITY OF MARYLAND SCHOOL OF MEDICINE

 

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CREDIT: UNIVERSITY OF MARYLAND SCHOOL OF MEDICINE

A drug approved to treat pulmonary arterial hypertension may be effective at managing hypertension and end-organ damage in patients with sickle cell disease, according to a new study published in Lancet Haematology. An early phase randomized clinical trial involving 130 patients with sickle cell disease found that the drug, called riociguat, was found to be safe to use and well tolerated in these patients and significantly improved their blood pressure. Preliminary efficacy data suggested the medication might improve heart function.

An estimated 100,000 Americans have sickle cell disease, and the disease occurs in about 1 out of every 365 Black or African-American births, according to the Centers for Disease Control and Prevention. People with sickle cell disease are at high risk for vascular complications that can lead to pulmonary hypertension, stroke, and kidney failure as well as severe pain when red blood cells block blood flow through tiny blood vessels in the chest, abdomen, and joints. These complications can be worsened by hypertension.

Unfortunately, previous research found that sildenafil, an effective treatment for pulmonary hypertension, caused unacceptable side effects in patients with sickle cell disease. It found that those who took this drug experienced high levels of pain that caused increased admissions to the hospital compared to those who took a placebo treatment.

This new study was designed to test the safety of riociguat and how well it works in preventing or reducing the clinical complications for patients with sickle cell disease.

In the study, patients with sickle cell disease and mild hypertension or protein in their urine (an early sign of kidney disease) were randomly assigned to receive either riociguat or a placebo in a double-blind clinical trial. Both groups received the study drug at a starting dose of 1 milligram, which was gradually increased up to 2.5 milligram, taken three times a day for 12 weeks. The researchers found that among the participants who took riociguat, 22.7 percent experienced at least one serious adverse event related to the treatment. In comparison, in the group that received the placebo, 31.3 percent of participants had at least one serious adverse event during the study.

The differences were not statistically significant. There were no differences between the two groups in the rates of pain severity, pain interference in their daily lives, and in vascular events related to their sickle cell disease. When it comes to the effectiveness of the drug treatment, participants who took riociguat had their blood pressure drop by 8.20 mmHg, while those who took a placebo only saw a decrease of about 1.24 mmHg. The result was highly statistically significant, meaning riociguat was much more effective at lowering blood pressure compared to the placebo, with a difference of approximately 6.96 mmHg. In summary, riociguat was found to be safe and led to a significant improvement of blood pressure over the duration of the study.

“Our results are encouraging and open the door to larger clinical trials involving this class of drugs in patients with sickle cell disease who have pulmonary hypertension or kidney disease. Having a drug that’s easy to tolerate can help them better manage their blood pressure and help prevent serious complications down the road,” said study leader Mark T. Gladwin, MD,  who is the John Z. and Akiko K. Bowers Distinguished Professor and Dean of UMSOM, and Vice President for Medical Affairs at University of Maryland, Baltimore.

Bayer Pharmaceuticals, manufacturer of riociguat, provided funding (as well as the drug and placebo) for the study.

The study was led by the clinical and data coordinating centers at the University of Pittsburgh. Study co-authors included faculty from the University of Illinois at Chicago, Albert Einstein College of Medicine, University of Pittsburgh, Emory University, Duke University, Johns Hopkins School of Medicine, and other institutions.

About the University of Maryland School of Medicine

Now in its third century, the University of Maryland School of Medicine was chartered in 1807 as the first public medical school in the United States. It continues today as one of the fastest growing, top-tier biomedical research enterprises in the world -- with 46 academic departments, centers, institutes, and programs, and a faculty of more than 3,000 physicians, scientists, and allied health professionals, including members of the National Academy of Medicine and the National Academy of Sciences, and a distinguished two-time winner of the Albert E. Lasker Award in Medical Research. With an operating budget of more than $1.2 billion, the School of Medicine works closely in partnership with the University of Maryland Medical Center and Medical System to provide research-intensive, academic and clinically based care for nearly 2 million patients each year. The School of Medicine has nearly $600 million in extramural funding, with most of its academic departments highly ranked among all medical schools in the nation in research funding. As one of the seven professional schools that make up the University of Maryland, Baltimore campus, the School of Medicine has a total population of nearly 9,000 faculty and staff, including 2,500 students, trainees, residents, and fellows. The combined School of Medicine and Medical System ("University of Maryland Medicine") has an annual budget of over $6 billion and an economic impact of nearly $20 billion on the state and local community. The School of Medicine, which ranks as the 8th highest among public medical schools in research productivity (according to the Association of American Medical Colleges profile) is an innovator in translational  medicine, with 606 active patents and 52 start-up companies. In the latest U.S. News & World Report ranking of the Best Medical Schools, published in 2021, the UM School of Medicine is ranked #9 among the 92 public medical schools in the U.S., and in the top 15 percent (#27) of all 192 public and private U.S. medical schools. The School of Medicine works locally, nationally, and globally, with research and treatment facilities in 36 countries around the world. Visit medschool.umaryland.edu.

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JOURNAL

The Lancet Haematology

DOI

10.1016/S2352-3026(24)00045-0 

METHOD OF RESEARCH

Randomized controlled/clinical trial

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Riociguat in patients with sickle cell disease and hypertension or proteinuria (STERIO-SCD): a randomised, double-blind, placebo controlled, phase 1–2 trial

 

‘Surprising’ hidden activity of semiconductor material spotted by researchers

PENN STATE

 

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VENKATRAMAN GOPALAN, PROFESSOR OF MATERIALS SCIENCE AND ENGINEERING AND OF PHYSICS, IN HIS OPTICAL LAB.  

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CREDIT: SEANA WOOD/PENN STATE MATERIALS RESEARCH INSTITUTE

UNIVERSITY PARK, Pa. — New research suggests that materials commonly overlooked in computer chip design actually play an important role in information processing, a discovery which could lead to faster and more efficient electronics. Using advanced imaging techniques, an international team led by Penn State researchers found that the material that a semiconductor chip device is built on, called the substrate, responds to changes in electricity much like the semiconductor on top of it. 

The researchers worked with the semiconductor material, vanadium dioxide, which they said shows great potential as an electronic switch. They also studied how vanadium dioxide interacts with the substrate material titanium dioxide and said they were surprised to discover that there seems to be an active layer in the substrate that behaves similarly to the semiconductor material on top of it when the semiconductor switches between an insulator — not letting electricity flow — and a metal — letting electricity flow. The revelation that substrates can play an active role in semiconductor processes is significant for designing future materials and devices, said study lead Venkatraman Gopalan, professor of materials science and engineering and of physics at Penn State. 

“New ideas are needed for smaller and faster electronics in order to keep up with Moore’s law,” said Gopalan, the corresponding author of the study in Advanced Materials. “One idea being pursued is materials, such as vanadium dioxide, that can switch between metal — the one state — and insulator — the zero state — states in a trillionth of a second. This is known as undergoing metal-insulator transitions.” 

The potential of vanadium dioxide as a metal-to-insulator transistor is well-documented and the material is considered promising for semiconductor technology due to its low energy consumption, Gopalan said. However, the material’s properties are still not fully understood, and until now, it has usually been observed in isolation rather than while functioning in a real device. 

Vanadium dioxide has strongly correlated electronic effects, meaning the repulsion between electrons interferes with the device, so cannot be ignored as is currently done in silicon-based electronics. This characteristic can result in materials with novel functionalities such as high-temperature superconductivity and enhanced magnetic properties.  

"The underlying physics of this material is less understood, and its performance in a device geometry is even lesser understood,” Gopalan said. “If we can make them work, there will be a renaissance in electronics. In particular, neuromorphic computing — where computer systems that take inspiration from the brains of living systems with neurons — could seriously benefit by using such devices.” 

The team investigated vanadium dioxide in a device rather than in isolation, applying a voltage to it to make it switch from an insulating to a conducting state. They used the Advanced Photon Source (APS) at Argonne National Laboratory, which uses powerful X-ray beams to study the behavior and structure of materials on the atomic level. When mapping the spatial and temporal response of the material to the switching event, the researchers observed unexpected changes to the structure of the material and substrate.  

“What we found was that as the vanadium dioxide film changes to a metal, the whole film channel bulges, which is very surprising,” Gopalan said. “Normally it is supposed to shrink. So clearly something else was going on in the film geometry that was missed before.” 

The APS X-ray penetrated through the vanadium dioxide film and into the titanium dioxide (TiO2) substrate — which is normally considered an electrically and mechanically passive material — that the thin film was grown on.  

"We found to our great surprise that this substrate is very much active, jiving and responding in completely surprising ways as the film switches from an insulator to a metal and back, when the electrical pulses arrive,” Gopalan said. “This is like watching the tail wagging the dog, which stumped us for a long while. This surprising and previously overlooked observation completely changes how we need to view this technology.” 

To understand these findings, the theory and simulation effort — led by Long-Qing Chen, Hamer Professor of Materials Science and Engineering, professor of engineering science and mechanics and of mathematics at Penn State — developed a theoretical framework to explain the entire process of the film and the substrate bulging instead of shrinking. When their model incorporated naturally occurring missing oxygen atoms in this material of two types, charged and uncharged, the experimental results could be satisfactorily explained. 

“These neutral oxygen vacancies hold a charge of two electrons, which they can release when the material switches from an insulator to a metal,” Gopalan said. “The oxygen vacancy left behind is now charged and swells up, leading to the observed surprising swelling in the device. This can also happen in the substrate. All of these physical processes are beautifully captured in the phase-field theory and modelling performed in this work for the first time by the postdoc Yin Shi in Professor Chen’s group.” 

Gopalan credited the multidisciplinary team’s combined expertise in material growth, synthesis, structure analysis and synchrotron beamline operation with the new understanding. Using a collaborative approach led by Greg Stone, a physical scientist with the U.S. Army and the lead experimental author, and Yin Chi, postdoctoral scholar at Penn State and the lead theory author, the researchers disentangled the material’s responses and observed them individually using phase field simulations, a simulation that helps scientists understand material changes over time by depicting various states of matter in a virtual setting. 

“By bringing these experts together and pooling our understanding of the problem, we were able to go far beyond our individual scope of expertise and discover something new,” said Roman Engel-Herbert, director of the Paul Drude Institute of Solid State Electronics in Berlin, Germany, and co-author of the study whose group grew these films along with Darrell Schlom’s group at Cornell University. “Recognizing the potential of functional materials necessitates an appreciation of their broader context, just as complex scientific challenges can only be solved through widening our individual perspectives.” 

The collaboration enabled both a significant amount of progress to happen in a short period of time and work to be done in a shorter period of time, and brought in a variety of perspectives from multiple disciplines. 

The responses themselves require further investigation, researchers said, but they believe that understanding them will assist in identifying previously unknown capabilities of vanadium dioxide, including potential yet-to-be discovered phenomena in the TiO2 substrate that was considered passive before this study. The study itself unfolded over 10 years, Gopalan noted, including validating the results. 

“This is what it takes to go from interesting science to a working device you can hold in the palm of your hand,” Gopalan said. “Experiments and theory are complex and require large-scale collaborative teams working closely together over an extended period of time to solve difficult problems that could have a large impact. We hope and expect that this will accelerate the progress towards a new generation of electronic devices.” 

Prior to his current position, Stone completed a postdoctoral fellowship at Penn State. Along with Gopalan, Engel-Herbert, Chen, Schlom, Stone and Chi, other authors of the paper include Matthew Jerry, graduate student, and Vladimir Stoica, research associate professor, both from Penn State; Hanjong Paik from Cornell University; Zhonghou Cai and Haidan Wen from Argonne National Laboratory, and Suman Datta from the Georgia Institute of Technology. The Department of Energy primarily supported this work. The U.S. National Science Foundation supported the film growth for this study. 

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JOURNAL

Advanced Materials

DOI

10.1002/adma.202312673 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

In-Operando Spatiotemporal Imaging of Coupled Film-Substrate Elastodynamics During an Insulator-to-Metal Transition