Tech

Swansea University researchers from the College of Engineering have captured the moments a fluid reacts like a solid through a new method of fluid observation under pressurised conditions.

The research comes from the Complex Flow Lab, based within the Institute for Innovative Materials, Processing and Numerical Technologies (IMPACT). The lab studies the intricate flow patterns that often develop in granular materials, porous media, and complex fluids such as foams, gels and pastes.

This latest study looks at fluids that have a solid-like response to stress, a phenomenon called Discontinuous Shear Thickening (DST). This is when liquid (in this case, a corn starch mixture) abruptly thickens and becomes solid when disturbed.

The tests involved a new method of observation involving a high-speed camera with results offering an innovative approach to future engineering practices.

Research author Dr Deren Ozturk, who recently completed his PhD in this area, comments:

"Our findings are of particular interest to the burgeoning DST field of research as it is a novel visual indication of DST behaviour that could be used to calibrate future theoretical models. The DST phenomenon is being researched for unique engineering applications such as soft body armour, "smart" speed bumps, and food production.

The research team used regular kitchen corn starch mixed with water. This is then placed in a narrow cell; pressurised air is released into the corn starch-water fluid and forces its way through.

How the air escapes is filmed using a high-speed camera to visualise invasion patterns - which either present as fluid-like fingers or solid-like fractures depending on the concentration of corn starch and the pressure in the air."

Dr Ozturk continues:

"We used corn starch (as a model system for the wider class of shear thickening materials) as it is convenient, widely available and shows a dramatic shear thickening response. As this kind of invasion experiment (which we have a lot of experience with) had not been previously performed on a DST fluid, our main objective was to just try them in the hopes of seeing something interesting.

Our main hypothesis was that the fluid would "fracture" like a solid if given enough stress. This would be a great thing to see since a fluid ought to exhibit wide finger patterns. We were, therefore, delighted to see a narrow fracturing response as this meant we had developed a new kind of experiment to probe the conditions for which DST is observed."

Co-author Dr Bjornar Sandnes, head of the Complex Flow Lab, comments:

"What is particularly interesting about the corn starch studied here is that friction can be turned on or off like a switch.

When only gently disturbed, the grains repel each other and since they are not in contact there is no friction and the material flows like a liquid.

Disturb it more forcefully however, and the grains are pushed into contact such that friction stops the grains freely sliding. The material then behaves more like a solid, and that is when we observe fracturing in our experiments."

In the spring of 2020, as Massachusetts experienced a surge in COVID-19 cases in the Boston area, four area hospitals conducted universal testing among all pregnant patients at the time of admission for SARS-CoV-2, the virus that causes COVID-19. At the time, Massachusetts had the third highest rate of infection in the country. In an analysis of the data collected during that time, a team of investigators from Brigham and Women's Hospital found no association between the number of in-person health care visits and risk of infection with SARS-CoV-2. Results are published in JAMA.

"One major concern in obstetrics, but also in general medicine, is that patients are avoiding necessary medical care because of fear of contracting COVID-19 in a health care setting, but there was no indication that in-person health care affects risk of infection," said corresponding author Sharon Reale, MD, an attending anesthesiologist in the Department of Anesthesiology, Perioperative and Pain Medicine. "Our study provides important evidence that we can do in-person visits safely. Our findings should be reassuring for our obstetrical patients that when they come to the hospital for appointments, they are not increasing their risk of infection."

While some patients could benefit from virtual visits via telemedicine during the spring, pregnant patients are a unique population. Many require multiple, in-person visits for measurements, exams and lab tests to ensure the health of both mother and baby or babies. Since April 19 and continuing through today, four Mass General Brigham hospitals -- Brigham and Women's Hospital, Massachusetts General Hospital, Newton-Wellesley Hospital and North Shore Medical Center -- test all obstetrical patients for COVID-19 when they are admitted. In the study, Reale and colleagues looked at patients delivering between April 19 and June 27, 2020.

To conduct their study, Reale and colleagues used a case-control approach in which patients who tested positive (cases) were matched to those who tested negative (controls) based on gestational age, race/ethnicity, insurance type and the rate of COVID-19 in the patients' zip code. The team also adjusted for age, body mass index and essential worker occupation.

Of close to 3,000 women who delivered during the study period, 111 patients tested positive. On average, patients who tested positive attended 3.1 visits in person (with a range of 0 to 10 visits); patients who tested negative attended an average of 3.3 visits in person (with a range of 0 to 16 visits). The authors conclude that there was no meaningful association between in-person visits and infection among the patients studied.

The authors note that their patient population included obstetrical patients only -- future studies will be needed to confirm if the findings extend to other patients. Reale also notes that Mass General Brigham adopted universal masking early on to help reduce transmission.

"Results will need to be replicated outside of obstetrics, but this should be reassuring and indicate that necessary and important care should be done and can be done safely," said Reale.

There was no funding organization for this study.

EUGENE, Ore. - Aug. 14, 2020 - Volcanic eruptions in the Cascade Range of the Pacific Northwest over the last 2.6 million years are more numerous and closely connected to subsurface signatures of currently active magma than commonly thought, according to newly published research.

A synthesis of volcanic vents on the surface and data that probes the structure and composition of the crust to a depth of 20 kilometers (12.4 miles) makes clear new connections between surface and subsurface evidence of past volcanic eruptions. The activity has stretched far beyond the 11 well known stratovolcanoes lining the Cascade Arc between northern California and northern Washington.

The study, led by University of Oregon scientists, catalogued almost 3,000 volcanoes associated with the mountain range. It was published July 13 in the journal Geology.

The research reveals new details about the complex and time-evolving patterns of rising magma in the region, said study co-author Leif Karlstrom, a professor in the UO Department of Earth Sciences and Oregon Center for Volcanology.

"Anyone who has ever flown between San Francisco and Seattle has probably marveled at the massive stratovolcanoes lined up between northern California and southern British Columbia," he said. "Remarkably, these landforms represent less than 1 percent of the volcanoes in the Cascades that have erupted in the geologically recent past."

The three-member research team examined 2,835 vents. They used freely available satellite-derived 3D digital terrain models to update estimates of eruption rates and synthesize subsurface observations over recent decades to map where signs of active magma in the crust correlates with edifices on the surfaces around the region's volcanos.

Edifices refer to the main portion of volcanoes built by erupted lava, rock projectiles, mud and debris flows, and mixture of rock fragments, gas and ash.

The 3D models allowed the research team to associate volcanic edifices with underlying seismic velocities, heat flow, gravity and deformation that are sensitive to the presence of magma, Karlstrom said. The work, he added, showed where surface vents seem to overlay currently active magma transport structures in the crust.

"Previous studies have analyzed single volcanoes or volcanic clusters with satellite data, but this is the first study to constrain volcano geometries over an entire arc in a self-consistent manner," said the study's lead author, Daniel O'Hara, a UO doctoral student. "We estimate that volcanic edifices represent about 50 percent of total volcanic output during the time-period we examined."

The research, he added, indicated a systematic decrease in the strength of these relationships, suggesting that eruptions as well as their underlying plumbing systems have migrated during the past 2.6 million years.

The National Science Foundation-funded research can help guide more in-depth studies of distributed volcanic vents and in assessing hazards and risks to people and infrastructure, said co-author David W. Ramsey of the U.S. Geological Survey's Cascades Volcano Observatory in Vancouver, Washington.

Distributed volcanic vents are associated with small cinder cones that cover much of the central Oregon Cascades, and area such as the Boring Lava Field in the city of Portland and the Medicine Lake volcano in California.

"This research used a consistent methodology to analyze volcanic vents spanning the entire U.S. Cascade Range over the last 2.6 million years," Ramsay said. "It helps to highlight recently active volcanic vents, particularly in central Oregon and northern California, and shows that the locations of potential future eruptions are not limited to the snow-capped stratovolcanoes on the horizon."

The region's major stratovolcanoes stretch along the junction of the Juan de Fuca and North American plates. From north to south, they are Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, Mount Adams, Mount Hood, Mount Jefferson, Three Sisters, Crater Lake/Mount Mazama, Mount Shasta and Lassen Peak.

First appearing in late 2019 in Wuhan City, China, the SARS-CoV-2 virus continues to cause sickness and death across the globe. Researchers and scientists have been looking at multiple solutions to treat COVID-19, including repurposing approved pharmaceutical drugs. This research points to very promising treatment options.

A team of researchers at the Pritzker School of Molecular Engineering (PME) at the University of Chicago used state-of-the-art computer simulations to identify a preexisting drug that could fast-track a solution to this worldwide pandemic.

Their findings appear in the paper, "Molecular Characterization of Ebselen Binding Activity to SARS CoV 2 Main 4 Protease," which was published on August 14 in the journal Science Advances.

Mpro Versus Ebselen

Early in February, concerned by the rapid progress of the pandemic, Professor Juan de Pablo and his students used their molecular modeling expertise to help find a treatment against the disease. They were not the only ones. Other groups around the world were beginning to use supercomputers to rapidly screen thousands of existing compounds for potential use against the SARS-CoV-2 virus.

"By virtue of the large number of compounds considered in high throughput screens, those calculations must necessarily involve a number of simplifications, and the results must then be evaluated using experiments and more refined calculations," de Pablo explained.

Researchers first focused on finding a weakness in the virus to target. They chose its main protease: Mpro. Mpro is a key coronavirus enzyme that plays a central role in the virus' life cycle. It facilitates the virus' ability to transcribe its RNA and replicate its genome within the host cell.

A pharmaceutical drug that shows promise as a weapon against Mpro is Ebselen. Ebselen is a chemical compound with anti-viral, anti-inflammatory, anti-oxidative, bactericidal, and cell-protective properties. Ebselen is used to treat multiple diseases, including bipolar disorders and hearing loss. In combination with silver, Ebselen treats five clinically difficult-to-manage antibiotic-resistant Gram-negative bacteria. Several clinical trials have proven its safety for use in humans.

How It Works

de Pablo and his students set out to develop detailed models of the enzyme and the drug. Using those models and sophisticated supercomputer simulations, they discovered that the small Ebselen molecule is able to decrease Mpro's activity in two different ways.

"In addition to binding at the catalytic site of the enzyme, Ebselen also binds strongly to a distant site, which interferes with the enzyme's catalytic function by relying on a mechanism in which information is carried from one region of a large molecule to another region far away from it through subtle structural reorganizations," de Pablo says.

That finding was particularly important because it helped explain Ebselen's potential efficacy as a repurposed drug, and it revealed a new vulnerability in the virus that was previously not known and that could be use useful in developing new therapeutic strategies against COVID-19.

By working around the clock, the team completed their work in just over two months and submitted their manuscript to public research archives in April for others to consider.

Drug Development Potential

The research team's discovery of two binding sites looks promising for Ebselen to be a new drug lead for the design and development of new Mpro inhibitors and COVID-19 treatment. Motivated by their findings, de Pablo and his student are quick to point out that much work is yet to be done.

"The main protease is one of many proteins in the virus that could be targeted with existing, repurposed drugs, and there are thousands of compounds to be considered," de Pablo says. "We are systematically investigating each of the proteins involved in the virus function and investigating their vulnerabilities and their responses to a wide range of drugs."

de Pablo and his team will soon release a comprehensive study of the RBD/ACE2 complex from the virus and another drug that offers promise to interfere with the binding of the virus to cells.

NASA-NOAA's Suomi NPP satellite provided forecasters with a visible image of Tropical Storm Josephine east of the Lesser Antilles island chain. Suomi NPP revealed that Josephine was being affected by wind shear.

The Lesser Antilles is a group of islands that form the boundary of the western Atlantic Ocean and the Caribbean Sea (to the west). They are a long, partly volcanic island arc stretching between the Greater Antilles to the north-west and South America.

On Aug. 13, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP revealed southwesterly wind shear was pushing the bulk of clouds and precipitation to the northeast of the center, giving the storm an elongated appearance.

Vertical wind shear, that is, winds outside of a tropical cyclone at different heights in the atmosphere (the troposphere), pushes against a tropical cyclone and tears it apart.

On Aug. 14, National Hurricane Center hurricane forecaster Jack Beven noted that wind shear was continuing. Beven said, "Morning visible satellite imagery indicates that the center of Josephine is located to the south or southwest of the strongest area of convection, likely due to the onset of southwesterly vertical wind shear."

Tropical Storm Josephine on Aug. 14

At 11 a.m. EDT (1500 UTC) on Aug. 14, the center of Tropical Storm Josephine was located near latitude 16.1 degrees north and longitude 54.7 degrees west. The storm was centered 575 miles (920 km) east-southeast of the southern Leeward Islands.

Josephine is moving toward the west-northwest near 16 mph (26 kph), and this general motion is expected to continue for the next couple of days. The estimated minimum central pressure was 1006 millibars. Maximum sustained winds were near 40 mph (65 km/h) with higher gusts. Some strengthening is possible during the next 24 hours. After that time, Josephine is expected to encounter upper-level winds that will not be conducive for strengthening.

Josephine is expected to turn toward the northwest late this weekend or early next week. On the forecast track, the center of Josephine is expected to pass to the northeast of the Leeward Islands over the weekend.

NASA Researches Tropical Cyclones

Hurricanes/tropical cyclones are the most powerful weather events on Earth. NASA's expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

For more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America's leadership in space and scientific exploration.

NASA-NOAA's Suomi NPP satellite provided forecasters with a visible image of a struggling Tropical Depression 10E in the Eastern Pacific Ocean. Wind shear is preventing the storm from intensifying into a tropical storm.

On Aug. 13, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP revealed northeasterly wind shear had exposed the center of circulation and pushed the bulk of clouds and precipitation to the southwest of the center. The depression has maintained a small ragged band of convection in its southwest quadrant.

Vertical wind shear, that is, winds outside of a tropical cyclone at different heights in the atmosphere (the troposphere), pushes against a tropical cyclone and tears it apart.

National Hurricane Center forecaster David Zelinsky noted, "Strong northeasterly shear should continue to limit the development potential of the cyclone, but upper-level winds could become less hostile in a few days."

Tropical Depression 10E on Aug. 14

At 11 a.m. EDT (1500 UTC) on Aug. 14, the center of Tropical Depression 10E was located near latitude 13.6 degrees north and longitude 131.9 degrees west. 10E is centered about 1,575 miles (2,535 km) west-southwest of the southern tip of Baja California, Mexico.

The depression is moving toward the west-southwest near 6 mph (9 kph). A slow drift toward the west-southwest is expected today, followed by a turn toward the northwest over the weekend. The estimated minimum central pressure is 1004 millibars. Maximum sustained winds are near 35 mph (55 kph) with higher gusts. Little change in strength is forecast during the next few days.

Almost all life on Earth, in particular our food and our health, depend on metabolism in plants. In order to understand how these metabolic processes function, researchers at the Institute of the Biology and Biotechnology of Plants at the University of Münster with the participation of the University of Bonn are studying key mechanisms in the regulation of energy metabolism. Now, for the first time, a new method of in vivo biosensor technology has enabled them to monitor in real time what effects environmental changes - for example, light, temperature, aridity, flooding or pest infestation - have on the central metabolism of the model plant Arabidopsis thaliana (thale cress). The study has appeared as an advance publication in the journal "The Plant Cell".

Background and methodology

The team of researchers expressed a genetically coded sensor inside the plants in order to make central metabolic process literally 'visible'. "Because plants appear from the outside to be very static, they have to be superfast masters of flexibility and adaptation within their cells," says Dr. Janina Steinbeck, lead author of the study. "We're now able to observe those dynamics live in the living plant." In order to measure the metabolic process in the plant and produce images of it, the researchers used in vivo biosensoring, a method for studying living organisms, tissue or cells in real time. The biosensor consists of a biological recognition element, a protein which specifically binds a molecule to be detected, and a read-out element, a protein which translates the binding to the recognition element into a light signal. The biosensor now being used was originally developed for use in nerve cells. The researchers refined this sensor and developed it so that it could be used in plants.

The sensor can directly bind and then release the molecules NAD+ and NADH. The so-called NAD redox system is of paramount importance for electron transfer during metabolism in almost all living things. The sensor consists of a fluorescent blue-green protein and a red one, both of which change their brightness depending on the NAD status in the cell. The sensor read-out in living cells is carried out with a modern confocal laser scanning microscope. The possibility of using NAD in vivo sensing in plants opens up new options for plant researchers. "For us, this new method is an achievement regarding the methodology because now we can gain a direct understanding of metabolic processes precisely where they occur in the plant," explains Prof. Markus Schwarzländer, who heads the Plant Energy Biology working group at the University of Münster. "For example, it was a complete surprise for us to observe that such a key process as NAD metabolism changes so fundamentally during an immune reaction," he adds.

Up to now, it had only been possible for the researchers to study this type of metabolic processes by obtaining extracts from the plants and analysing them with biochemical methods. In this approach, however, cells and tissue are destroyed, and it is no longer possible to trace where exactly the metabolic changes occurred. Now, the researchers can track dynamic changes in the redox metabolism - which, among other functions, serves to provide energy in the cells - from specific cell compartments, here in the cytosol, in the individual cells, up to complete organs in intact living plants. This approach makes it possible to create a first NAD redox map of the whole plant and to observe redox dynamics in transitions from light to dark as well as changes in the sugar status, cell respiration and oxygen supply. "As a result, it becomes apparent just how directly metabolism and environment are linked," says Markus Schwarzländer. "What was especially exciting was the new connection to the immune response, which we previously had practically no idea about, and which now needs to be studied in more depth."

At almost the same time as the publication in The Plant Cell, a study by researchers in Hong Kong was published in Nature Communications. In this study, a different sensor for NAD was expressed inside plants and used to study photosynthesis. The results of both studies support each other. "The information gained through the new method can play a key role in future in cultivating plants which make our food production more sustainable and contribute to alleviating the effects of climate change. A direct early recognition of stress in agricultural crops might also be possible," says Schwarzländer, with a view to the future.

HOUSTON -- Two different types of detectable antibody responses in SARS-CoV-2 (COVID-19) tell very different stories and may indicate ways to enhance public health efforts against the disease, according to researchers at The University of Texas MD Anderson Cancer Center. Antibodies to the SARS-CoV-2 spike protein receptor binding domain (S-RBD) are speculated to neutralize virus infection, while the SARS-CoV-2 nucleocapsid protein (N-protein) antibody may often only indicate exposure to the virus, not protections against reinfection.

The results, published today in JCI Insight, highlight findings from a quantitative serological enzyme-linked immunosorbent assay (ELISA) using SARS-CoV-2 S-RBD and N-protein for the detection of circulating antibodies in 138 serial serum samples from confirmed COVID-19 hospitalized patients and 464 healthy and non-COVID-19 serum samples that were collected between June 2017 and June 2020.

Results showed that 3% of healthy and non-COVID-19 samples collected during the pandemic in Houston were positive for the N-protein antibody, but only 1.6% of those had the S-RBD antibody. Of samples with the S-RBD antibody, 86% had neutralizing capacity - meaning they could prevent reinfection of COVID-19, but only 74% of samples with N-protein had neutralizing capacity. When positive for both, 96.5% exhibited neutralizing capacity.

"These findings suggest that detection of N-protein binding antibodies does not always correlate with presence of S-RBD neutralizing antibodies, and that the presence of the S-RBD antibody is the best indicator of any potential protection against reinfection," said senior author Raghu Kalluri, M.D., Ph.D., professor and chair of Cancer Biology. "We caution against the extensive use of N-protein based serology testing for determination of potential COVID-19 immunity, and we believe that accurate and reliable S-RBD serological testing is needed to carefully identify individuals with neutralizing antibodies in order to help advance recovery efforts around the globe."

At present, some commercially available serological tests confirm only the presence antibodies to the N-protein, with over 200 commercial and hospital laboratory testing facilities currently using these tests. While these tests indicate exposure to the virus, they do not seem to suggest immunity to reinfection. These findings reiterate the need to educate on what an antibody test result mean for each patient, and that public health efforts should focus on ways to encourage patients to continue vigilant safety precautions even with the presence of N-protein antibodies.

"In addition to serological assessment of the general population, we are hopeful these results will aid in rapid assessment of the efficacy of vaccine candidates as they are translated into the broader population," said lead author Kathleen McAndrews, Ph.D., postdoctoral fellow in Cancer Biology.

Two UCLA computer scientists have shown that existing compilers, which tell quantum computers how to use their circuits to execute quantum programs, inhibit the computers' ability to achieve optimal performance. Specifically, their research has revealed that improving quantum compilation design could help achieve computation speeds up to 45 times faster than currently demonstrated.

The computer scientists created a family of benchmark quantum circuits with known optimal depths or sizes. In computer design, the smaller the circuit depth, the faster a computation can be completed. Smaller circuits also imply more computation can be packed into the existing quantum computer. Quantum computer designers could use these benchmarks to improve design tools that could then find the best circuit design.

"We believe in the 'measure, then improve' methodology," said lead researcher Jason Cong, a Distinguished Chancellor's Professor of Computer Science at UCLA Samueli School of Engineering. "Now that we have revealed the large optimality gap, we are on the way to develop better quantum compilation tools, and we hope the entire quantum research community will as well."

Cong and graduate student Daniel (Bochen) Tan tested their benchmarks in four of the most used quantum compilation tools. A study detailing their research was published in IEEE Transactions on Computers, a peer-reviewed journal.

Tan and Cong have made the benchmarks, named QUEKO, open source and available on the software repository GitHub.

Quantum computers utilize quantum mechanics to perform a great deal of computations simultaneously, which has the potential to make them exponentially faster and more powerful than today's best supercomputers. But many issues need to be addressed before these devices can move out of the research lab.

For example, due to the sensitive nature of how quantum circuits work, tiny environmental changes, such as small temperature fluctuations, can interfere with quantum computation. When that happens, the quantum circuits are called decoherent -- which is to say they have lost the information once encoded in them.

"If we can consistently halve the circuit depth by better layout synthesis, we effectively double the time it takes for a quantum device to become decoherent," Cong said.

"This compilation research could effectively extend that time, and it would be the equivalent to a huge advancement in experimental physics and electrical engineering," Cong added. "So we expect these benchmarks to motivate both academia and the industry to develop better layout synthesis tools, which in turn will help drive advances in quantum computing."

Cong and his colleagues led a similar effort in the early 2000s to optimize integrated circuit design in classical computers. That research effectively pushed two generations of advances in computer processing speeds, using only optimized layout design, which shortened the distance between the transistors that comprise the circuit. This cost-efficient improvement was achieved without any other major investments in technological advances, such as physically shrinking the circuits themselves.

"Quantum processors in existence today are extremely limited by environmental interference, which puts severe restrictions on the length of computations that can be performed," said Mark Gyure, executive director of the UCLA Center for Quantum Science and Engineering, who was not involved in this study. "That's why the recent research results from Professor Cong's group are so important because they have shown that most implementations of quantum circuits to date are likely extremely inefficient and more optimally compiled circuits could enable much longer algorithms to be executed. This could result in today's processors solving much more interesting problems than previously thought. That's an extremely important advance for the field and incredibly exciting."

Nature's blueprint for the human limb is a carefully layered structure with stiff bone wrapped in layers of different soft tissue, like muscle and skin, all bound to each other perfectly. Achieving this kind of sophistication using synthetic materials to build biologically inspired robotic parts or multicomponent, complex machines has been an engineering challenge.

By tweaking the chemistry of a single polymer, researchers at Texas A&M University and the U.S. Army Combat Capabilities Development Command Army Research Laboratory have created a whole family of synthetic materials that range in texture from ultra-soft to extremely rigid. The researchers said their materials are 3D printable, self-healing, recyclable and they naturally adhere to each other in air or underwater.

Their findings are detailed in the May issue of the journal Advanced Functional Materials.

"We have made an exciting group of materials whose properties can be fine-tuned to get either the softness of rubber or the strength of load-bearing plastics," said Dr. Svetlana Sukhishvili, professor in the Department of Materials Science and Engineering and a corresponding author on the study. "Their other desirable characteristics, like 3D printability and the ability to self-heal within seconds, make them suited for not just more realistic prosthetics and soft robotics, but also ideal for broad military applications such as agile platforms for air vehicles and futuristic self-healing aircraft wings."

Synthetic polymers are made up of long strings of repeating molecular motifs, like beads on a chain. In elastomeric polymers, or elastomers, these long chains are lightly crosslinked, giving the materials a rubbery quality. However, these crosslinks can also be used to make the elastomers more rigid by increasing the number of crosslinks.

Although previous studies have manipulated the density of crosslinks to make elastomers stiffer, the resulting change in mechanical strength was generally permanent.

"Crosslinks are like stitches in a piece of cloth, the more stitches you have, the stiffer the material gets and vice versa," said Sukhishvili. "But instead of having these 'stitches' be permanent, we wanted to achieve dynamic and reversible crosslinking so that we can create materials that are recyclable."

So, the researchers focused their attention on the molecules involved in the crosslinking. First, they chose a parent polymer, called prepolymer, and then chemically studded these prepolymer chains with two types of small crosslinking molecules -- furan and maleimide. By increasing the number of these molecules in the prepolymer, they found that they could create materials stiffer. In this way, the hardest material they created was 1,000 times stronger than the softest.

However, these crosslinks are also reversible. Furan and maleimide participate in a type of reversible chemical bonding. Put simply, in this reaction, furan and maleimide pairs can "click" and "unclick" depending on temperature. When the temperature is high enough, these molecules come apart from the polymer chains and the materials soften. At room temperature, the materials harden since the molecules quickly click back together, once again forming crosslinks. Thus, if there is any tear in these materials at ambient temperatures, the researchers showed that furan and maleimide automatically re-click, healing the gap within a few seconds.

The researchers noted that the temperatures at which the crosslinkers dissociate or unclick from the prepolymer chains are relatively the same for different stiffness levels. This property is useful for 3D printing with these materials. Regardless of whether they are soft or hard, the materials can be melted at the same temperature and then used as printing ink.

"By modifying the hardware and processing parameters in a standard 3D printer, we were able to use our materials to print complex 3D objects layer by layer," said Dr. Frank Gardea, research engineer in the United States Army Research Laboratory and a corresponding author on the study. "The unique advantage of our materials is that the layers that make up the 3D part can be of vastly different stiffness."

As the 3D part cools to room temperature, he added that the different layers join seamlessly, precluding the need for curing or any other chemical processing. Consequently, the 3D-printed parts can easily be melted using high heat and then recycled as printing ink. The researchers also noted that their materials are reprogrammable. In other words, after being set into one shape, they can be made to change into a different shape using just heat.

In the future, the researchers plan to increase the functionality of their new materials by amplifying its multifaceted properties outlined in the current study.

"Right now, we can easily achieve around 80% self-healing at room temperature, but we would like to reach 100%. Also, we want to make our materials responsive to other stimuli other than temperature, like light," said Gardea. "Further down the road, we'd like to explore introducing some low-level intelligence so that these materials know to autonomously adapt without needing a user to initiate the process."

A new study from the Beckman Institute for Advanced Science and Technology describes how existing infrared technology can be adapted to measure recognition memory and other cognitive outcomes in infants.

The study demonstrated that the eye tracking technology and computer-controlled stimulus presentation can be successfully used to automate assessments of infant looking behaviors to measure specific cognitive functions. The outcomes were similar to those found in previous studies using nonautomated techniques. The results also support the hypothesis that infants have side and stimulus preferences that affect their performance on specific cognitive outcomes.

The study "Characterization of performance on an automated visual recognition memory task in 7.5-month-old infants" was published in Neurotoxicology and Teratology.

"Traditionally, eye-tracking studies require you to keep your head still and avoid any movement so that the eye tracker can work properly," said Andrea Aguiar, a research assistant professor of comparative biosciences at the University of Illinois at Urbana-Champaign. "This is not a feasible method when you study infants. Additionally, we needed an automated approach that was not subjected to individual examiners' biases."

Typically, behavior studies on infants are carried out in the presence of trained examiners who need to decide where the babies are looking. Unfortunately, this approach is problematic because there is a lot of variation across examiners. Using the infrared eye tracker eliminates that variation.

"We have the infants sit on their mom's lap and ask the mom to look down at the baby's head and remain neutral. We then display pictures of faces and shapes on a big screen and calibrate the eye tracker," said Francheska M. Merced-Nieves, a former graduate student in the Children's Environmental Health Research Center. "The babies wear a target sticker in the middle of their forehead and the eye tracker measures the distance between the sticker and their cornea."

The goals of the study were to characterize infant looking behavior measures including side preference, fixation duration, and novelty preference using eye tracking and an automated version of an established technique that includes both human faces and geometric figures as stimuli. More than 300 infants, which are part of the ongoing Illinois Kids Development Study, were assessed using the automated technique.

In accordance with prior studies, the researchers saw that the infants spent a longer time looking at novel stimuli, indicating that they prefer those images. "We also confirmed the idea that most babies have a natural tendency to look toward their right side. Interestingly, when they were looking at the faces, they preferred looking at the eyes compared to the rest of the face," said Susan Schantz, a professor emeritus of comparative biosciences and the director of the center.

The researchers hope to use this technique to look at the impact of various prenatal exposures on cognitive development in babies. Currently, they are interested in measuring how maternal stress impacts early cognition.

"We show the babies images and see how long they focus on them before looking away," Merced-Nieves said. "We saw that higher maternal stress was associated with lower focus, which would indicate problems with attention."

Unfortunately the system is expensive, but the researchers hope that the convenience and versatility afforded by a mobile eye-tracking test unit that they have designed will encourage other epidemiological research groups to adopt their method and paradigm. The mobile test unit, which can be set up in less than 30 minutes, replicates the setting in the researchers' Beckman infant lab; thus allowing researchers in very different settings to test infants under similar conditions.

Influenza-specific bone marrow plasma cells - responsible for maintaining the level of protective antibodies following a flu shot - are short-lived, and decline to their pre-vaccination levels within a year, researchers report. While the findings help explain the lackluster persistence of the antibody response often observed from the annual influenza vaccination, the new study offers insight into how the longevity of the next generation of vaccines could be enhanced. Ideally, a successful vaccine stimulates the body's adaptive immunity to produce pathogen-specific antibodies, which imbues an individual with long-lasting protection against future infection. For many vaccines, the levels of a new antibody peak in the months following vaccination and decline to a "plateau level" that can be maintained for decades. However, this is not the case for common influenza vaccines; antibody levels and protective immunity decline rapidly after each seasonal vaccination. In a novel clinical study that spanned eight flu seasons and 53 participants, Carl Davis and colleagues tracked the production and maintenance of influenza-specific bone marrow plasma cells (BMPCs) following flu vaccination. Davis et al. collected bone marrow samples pre-vaccination, one month post-vaccination and one year post-vaccination, which allowed the authors to assess the long-term vaccine response and antibody maintenance. For some individuals, they assessed this for several seasonal vaccination cycles. The results showed that vaccination did spur the generation of influenza-specific BMPC, which were present in increased numbers a month following immunization. However, most of the newly formed BMPC were quickly lost, returning to pre-vaccination levels within a year. Despite this, Davis et al. show that a small number did persist more than a year, suggesting that the longevity of flu vaccines can be improved.

Since the late 1990s, immunotherapy has been the frontline treatment against lymphomas where synthetic antibodies are used to stop the proliferation of cancerous white blood cells. However, in the more than 20 years since their use began, the molecular mechanisms that underlie this therapy are still little understood. For the first time, scientists from the CNRS, Institut Pasteur and Université de Bordeaux have observed the interaction between therapeutic antibodies and their target protein. The research, published in Science on 14 August 2020, describes these molecular mechanisms and opens the way to the development of new treatments.

Non-Hodgkin lymphomas are among the most common cancers affecting almost 1.5 million people globally. They cause uncontrolled proliferation of B lymphocytes, a type of white blood cell, to the detriment of healthy cells. Since the end of the 1990s, immunotherapy had been a frontline treatment using synthetic antibodies to target a protein on the surface of B lymphocytes called CD20. The body's defences then identify these cells covered in antibodies as pathogens and destroy them.

Presently, the types of therapeutic antibodies used are classified into two groups according to how many CD20 molecules they bind to and the immunity response they trigger. Antibodies from the first group have the ability to interact with twice as many CD20 molecules than antibodies from the second group and can set off a cascading immune response called a "complement pathway". Until now, the molecular mechanisms at the root of underlying the differences between these two groups were unknown.

By using cryogenic electron microscopy, scientists from the CNRS, Institut Pasteur, and Université de Bordeaux1 were able, for the first time, to observe on an atomic level the interaction between the representatives of both groups of antibodies and their target molecules. They have shown that because of the availability of space, CD20 proteins can bind to two type 1 antibodies but to only one type 2 antibody. Due to their larger numbers on the surface of B lymphocytes, type 1 antibodies can form clusters. The team demonstrates that these clusters trigger the complement pathway which leads to the destruction of the target B lymphocytes. Type 2 antibodies, on the other hand, are thinly dispersed on the cell surface and therefore do not trigger a cascading response. Other independent immune responses are still able to destroy the cells.

Never before has the mechanism of action of therapeutic antibodies been described with such precision. This research could lead to new synthetic antibodies able to control a patient's immune response. In addition, this description of the mechanism activating the complement pathway opens the way to new research possibilities aiming at an understanding of how immune defences work.

Key knowledge gaps exist in our understanding of how ocean microplastics transport bacteria and viruses - and whether this affects the health of humans and animals, researchers say.

With millions of tons of plastic reaching the world's oceans every year - and trillions of particles floating on the surface - the potential impacts of plastic pollution are vast.

Plastic particles are known to carry specific combinations of metals, pollutants and pathogens (bacteria, viruses and other microorganisms that can cause disease).

But the new study, by the University of Exeter and the Centre for Environment, Fisheries and Aquaculture Science (Cefas), says critical questions remain about the role of microplastics in carrying pathogens, and possible threats to food production and safety.

The paper focusses on aquaculture (seafood farming), which is expected to play a vital role in feeding the world's growing population, and already faces challenges due to diseases.

"Microplastic fragments differ markedly from natural floating particles, and there is growing evidence that they represent a potential reservoir of pathogens," said Dr Ceri Lewis, of Exeter's Global Systems Institute.

"Of particular concern are the increasing reports of the presence of numerous pathogens on plastic surfaces in oceans around the world.

"One study found antimicrobial-resistant bacteria at concentrations 100-5,000 times higher on microplastic surfaces than in surrounding seawater.

"However, the effects of all this on marine animals, aquaculture and ultimately human health are really unknown at this point."

Many studies have suggested that disease transfer from plastic to ingesting organisms may occur, but this has not been demonstrated experimentally.

Seafood fears

Aquaculture is now the fastest-growing food sector, and bivalves (such as mussels and oysters) arguably offer the best route to increase production globally.

However, bivalves are filter-feeders and are known to take in microplastic particles from seawater.

"Understanding any risk of pathogen transport associated with microplastic is important for the aquaculture industry," said lead author Jake Bowley, of the University of Exeter.

"Disease is one of the biggest issues faced by the industry.

"We mapped the abundance of sea-surface plastics against areas of intensive aquaculture, and the results show a number of areas of high aquaculture production in microplastic hotspots where pathogen transfer could theoretically occur.

"One such hotspot is in China, where 57 microplastic particles per individual have been reported in the commercially important Yesso clam."

Dr Craig Baker-Austin, of Cefas, added: "Bacteria from a genus called vibrio - a globally important group of human and animal pathogens that are increasing in incidence - have been found in high levels on microplastics.

"Some vibrio bacteria are known to contribute to disease in bivalves, often causing mass mortality among larvae and in some cases mortality within adult bivalve populations."

This research is funded by insurer AXA XL through their Ocean Risk Scholarships Programme.

The programme funds PhD research that examines how the ocean is changing and how that will impact the current and future risk landscape.

Geir Myre, AXA XL's Global Head of Aquaculture, serves as a risk supervisor to Jake Bowley, providing advice on how this research is relevant to AXA XL and the wider aquaculture insurance industry.

Myre said: "Understanding the link between microplastics and the risk of transferring pathogens through shellfish is critical to our work to manage and transfer risk for the aquaculture industry.

"It's one of many emerging risks we must consider as a result of human impact on the ocean and highlights the connection between ocean risks and public health and safety."

Dr Lewis added: "There is a lot we still need to know about the impact of plastic pollution.

"Shining a light on this pressing environmental, food safety and microbiological issue is really important.

"However, it's likely that any negative impacts will get worse if we continue to dump plastic into the oceans at the current rate.

"We urgently need to move to more sustainable and circular economy approaches to our use of plastic materials to drastically reduce the input of plastics into the environment."

What The Article Says: Researchers report the clinicopathologic and autopsy findings observed in the olfactory system of two patients with SARS-CoV-2-positive nasal swabs.

Authors: Patrizia Morbini M.D., Ph.D., of the University of Pavia in Pavia, Italy, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamaoto.2020.2366)

Editor's Note: The article includes conflict of interest disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflicts of interest and financial disclosures, and funding and support.