The Science Thinkers

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Strontium Isotope Ratios in Fish Otoliths as Biogenic Tracers of Coal Combustion Residual Inputs to Freshwater Ecosystems

A Duke University study shows that trace elements in a fish's ear bones can be used to identify and track coal ash contamination in the waters where it lived.

"Calcified structures—or otoliths—found in a fish's inner ear are known to store a lot of life history information, including chemical and physical records of the fish's age, natal habitat and migration patterns," said Jessica Brandt, lead author of the paper and a 2018 Ph.D. graduate of Duke's Nicholas School of the Environment. "We've shown that otoliths also capture the signatures of contaminants that have affected the fish's ecosystems."


Brant and her team found that strontium isotope ratios in the otoliths of fish from two North Carolina lakes—both of which had received effluents from coal ash ponds at nearby power plants—matched the strontium isotope ratios in samples collected from sediment at the bottom of the lakes.

"This shows otoliths can be used as biogenic tracers to assess the potential for ecological impacts of coal ash waste streams in affected waters," said Brandt, who is now a postdoctoral researcher with the U.S. Geological Survey. "While strontium behaves differently than the toxic elements in coal ash effluents, it helps us connect high levels of those elements back to the contamination source."


Strontium is a naturally occurring trace element in coal that retains unique isotopic ratios even after the coal is burned and coal ash comes into contact with an aquatic environment.

Past studies have used strontium isotope ratios to track coal ash's impacts on water quality, "but this is the first time we've been able to prove they can also be used as fingerprints to track coal ash's impacts in living organisms," said Avner Vengosh, professor of geochemistry and water quality at Duke's Nicholas School, who coauthored the study.

"This definitely shows the strontium in the fish must be from coal ash contamination," Vengosh said. The Duke team published its peer-reviewed findings Nov. 21 in the journal Environmental Science & Technology Letters.


The researchers collected surface water and sediment-based pore water samples from two North Carolina lakes—Mayo Lake and Sutton Lake—that were historically impounded to provide cooling water for nearby power plants and to receive their effluents. Sutton Lake was the site of a large coal ash leak into the adjacent Cape Fear River after Hurricane Florence caused flooding this fall.

The researchers also collected surface and pore water samples from two sites located upstream from the lakes, and from two other lakes—Lake Tillery and Lake Waccamaw—that are not associated with coal ash waste streams. The samples were then analyzed in the laboratory, along with the otoliths of largemouth bass from each of the lakes.


"Strontium isotope ratios in the largemouth bass otoliths overlapped with ratios in corresponding sediment pore waters at all lakes and reservoirs, which is compelling evidence that otoliths can serve as biogenic tracers of coal ash effluents," said Richard Di Giulio, the Sally Kleberg Professor of Environmental Toxicology at Duke, who co-authored the study.

Strontium isotope ratios in surface water samples from the lakes didn't always match those in the fish otoliths and pore water samples, Di Giulio explained, but this could be because surface water ratios are more variable over time.


"This study's finding demonstrate that otolith studies can add to our existing research efforts," said Brandt. "Water-based strontium isotope tracers only give us information about coal ash impacts at a particular point in time, but because otoliths continuously grow over a fish's lifetime, we could use time-series analyses of otoliths to determine the timing of waste stream discharges or spills going back several years. This represents an emerging and important new direction in environmental toxicology and water-quality research."



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Designing Bioinspired Surfaces For Water Collection From Fog

Humans can get by in the most basic of shelters, can scratch together a meal from the most humble of ingredients. But we can't survive without clean water. And in places where water is scarce—the world's deserts, for example—getting water to people requires feats of engineering and irrigation that can be cumbersome and expensive. A pair of new studies from researchers at The Ohio State University offers a possible solution, inspired by nature.

"We thought: 'How can we gather water from the ambient air around us?'" said Bharat Bhushan, Ohio Eminent Scholar and Howard D. Winbigler Professor of mechanical engineering at Ohio State. "And so, we looked to the things in nature that already do that: the cactus, the beetle, desert grasses."


Their findings were published Dec. 24 in the journal Philosophical Transactions of the Royal Society. The works were co-authored with Ohio State Ph.D. student Dev Gurera and with Ohio State engineering researcher Dong Song.

Bhushan's work focuses on finding nature-inspired solutions to societal problems. In this case, his research team looked to the desert to find life that survives despite limited access to water.

The cactus, beetle and desert grasses all collect water condensed from night time fog, gathering droplets from the air and filtering them to roots or reservoirs, providing enough hydration to survive.


The cactus, beetle and desert grasses all collect water condensed from nighttime fog, gathering droplets from the air and filtering them to roots or reservoirs, providing enough hydration to survive.

Bhushan's team studied each of these living things and realized they could build a similar—albeit larger—system to allow humans to pull water from nighttime fog or condensation.

They started studying the ways by which different surfaces might collect water, and which surfaces might be the most efficient. Using 3-D printers, they built surfaces with bumps and barbs, then created enclosed, foggy environments using a commercial humidifier to see which system gathered the most water.


They learned that conical shapes gather more water than do cylindrical shapes—"which made sense, given what we know about the cactus," Bhushan said. The reason that happens, he said, is because of a physics phenomenon called the Laplace pressure gradient. Water gathers at the tip of the cone, then flows down the cone's slope to the bottom, where a reservoir is waiting.

Grooved surfaces moved water more quickly than ungrooved surfaces—"which seems obvious in retrospect, because of what we know about grass," Bhushan said. In the research team's experiments, grooved surfaces gathered about twice as much water as ungrooved surfaces.


The materials the cones were made out of mattered, too. Hydrophobic surfaces—those that allowed water to bead up rather than absorbing it—gathered the most water.

"The beetle's surface material is heterogeneous, with hydrophilic spots surrounded by hydrophobic regions, which allows water to flow more easily to the beetle's mouth," Bhushan explained.

The research team also experimented on a structure that included multiple cones, and learned that more water accumulated when water droplets could coalesce between cones that were one or two millimeters apart. The team is continuing those experiments, Bhushan said.


The work so far has been done on a laboratory-only level, but Bhushan envisions the work scaled up, with structures in the desert that could gather water from fog or condensation. That water, he thinks, could supplement water from public systems or wells, either on a house-by-house basis, or on a community-wide basis.

There is precedent for the idea: In areas around the world, including the Atacama Desert in Chile, large nets capture water from fog and collect it in reservoirs for farmers and others to use. Those nets might not be the most efficient way of harnessing water from the air, Bhushan believes.


"Water supply is a critically important issue, especially for people of the most arid parts of the world," Bhushan said. "By using bio-inspired technologies, we can help address the challenge of providing clean water to people around the globe, in as efficient a way as possible."



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Human ESC-Derived Chimeric Mouse Models of Huntington's Disease Reveal Cell-Intrinsic Defects in Glial Progenitor Cell Differentiation

The neurological disorder Huntington's disease causes behavioural and motor changes, which among other things are a result of dysfunctional maturation or formation of glial cells, the brain's support cells, researchers from the University of Copenhagen demonstrate in a new study based on mouse trials. The researchers' long-term goal is to be able to use the research results to develop a treatment for Huntington's disease using glial cells.

The brain's support cells, the so-called glial cells, play a main role in the development of the genetic brain disorder Huntington's disease, for which there is currently no treatment. In a new study, an international group of researchers from the Faculty of Health and Medical Sciences at the University of Copenhagen, among others, has now mapped important, hitherto unknown mechanisms in glial cells in a brain suffering from Huntington's disease. The new research results have been published in the prestigious journal Cell Stem Cell.


"In the study we show that glial cell maturation is severely impaired in patients with Huntington's disease, and this is a major contributor to the abnormalities we see in the brain. This leads to behavioural changes as well as to changes in motor function. The failure of glial maturation causes many of these symptoms, because diseased glial cells cannot support normal neuronal and synaptic function; this means that the communication between neurons is impaired," says the last author of the study, Professor Steve Goldman from the Center for Neuroscience at the University of Copenhagen and the Center for Translational Neuromedicine at University of Rochester.

Huntington's disease is the result of a mutation in a gene—the Huntingtin gene—which codes for a protein that, when mutated, causes the disease. Among other things, Huntington's disease leads to personality changes and a loss in motor coordination. There is currently no treatment that can cure or even slow the disease; at best, physicians can only offer medicines that can alleviate some of its symptoms. The overall goal of Steve Goldman and his research group is to find a meaningful, disease-modifying treatment for the disease.


They have been researching glial cells and degenerative diseases in the brain, including Huntington's disease, for a number of years, and in this study they set out to determine what happens to glial cells at the molecular level in the Huntington's disease brain. To do so the researchers studied mice into which they had transplanted human glial progenitor cells containing the Huntington gene. These glial progenitor cells are precursors to mature glial cells, and were derived from pluripotent stem cells, using methods that the researchers developed for producing glial cells from stem cells.

These mice with human glia enabled the researchers to study the development of Huntington disease-derived glial cells. The researchers learned that the maturation of the glia was delayed and imperfect. Among other things, this led to dysfunctional astrocytes, the most common type of glia in the brain, which among other things regulate the communication between neurons. This poor glial maturation also led to a lack of myelin, the insulating fat that surround the nerve pathways in the brain, and which normally allows and speeds neural communication. The result was a failure of the brain's white matter in these humanized mouse models of Huntington disease, with its consequent effects on behaviour and motor skills. Goldman argues that glial cells are not only important in connection with Huntington's disease, but also appear to play a main role in several other neurodegenerative and neuropsychiatric diseases, such as schizophrenia.


"This failure of glial cell maturation appears to be a common element of diseases that involve behavioural abnormalities and psychotic thinking. The unsuccessful glial cell maturation we saw in Huntington's disease is very similar to what we saw in one of our previous studies, where we studied the role of glial cells in schizophrenia. At the same time, our study stresses the potential of glial cell therapy as a possible treatment for Huntington's disease and other similar neurodegenerative diseases," Goldman explains.

Goldman and his colleagues have previously worked with glial cell transplantation, as described in a study from 2016. Here the researchers had transplanted healthy glial cells to mice suffering from Huntington's disease. This prolonged the life expectancy of the mice and alleviated the symptoms of the disease. And one of the next steps for Goldman and his research group is to conduct clinical trials involving transplantation of healthy glial cells to patients with Huntington's disease. They hope to be able to launch these trials within the next couple of years.




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Decline In Climate Resilience Of European Wheat

The climate is not only warming, it is also becoming more variable and extreme. Such unpredictable weather can weaken global food security if major crops such as wheat are not sufficiently resilient—and if we are not properly prepared.

A group of European researchers, including Professor Jørgen E. Olesen from the Department of Agroecology at Aarhus University, has found that current breeding programmes and cultivar selection practices do not provide the needed resilience to climate change.


Current breeding programmes and cultivar selection practices do not sufficiently prepare for climatic uncertainty and variability, the authors state in a paper recently published in PNAS (Proceedings of the National Academy of Sciences). Not only that, the response diversity of wheat on farmers' fields in most European countries has worsened in the past five to fifteen years, depending on country.

Researchers predict that greater variability and extremeness of local weather conditions will lead to reduced yields in wheat and increased yield variability.

"Needless to say, decreased yields are not conducive to food security, but higher yield variability also poses problems. It can lead to a market with greater speculation and price volatility. This may threaten stable access to food by the poor, which in turn can enhance political instability and migration," Jørgen E. Olesen points out.


The researchers base their assessments on thousands of yield observations of wheat cultivars in nine European countries for qualifying how different cultivars respond to weather. They identified the variation of wheat response diversity on farmers' fields and demonstrated the relation to climate resilience.

The yield responses of all cultivars to different weather events were relatively similar within northern and central Europe, and within southern European countries—the latter particularly with regard to durum wheat. There were serious gaps in wheat resilience across all Europe, especially with regard to yield performance under abundant rain.


"The lack of response diversity can pose serious problems with regard to food security. Therefore, farmers, breeders, and dealers in seeds and grain need to pay more attention to the diversity of cultivars grown," warns Professor Olesen.

Wheat is an important staple food crop in Europe and is the leading source of plant protein in our diet globally, so it is important to ensure that we have climate-resilient wheat cultivars on hand.


Rain, drought, heat or cold at vulnerable times during the growing season can seriously damage yields. Wheat yield is generally sensitive to even a few days of exposure to waterlogging and to wet weather that favours disease. In addition, heat stress rather than drought sensitivity appears to be a limiting factor for adaptation of wheat to climate change in Europe.

The dominant approach of adapting crops to climate change by tailoring genotypes to the most likely long-term change is likely insufficient. The capacity of a single crop variety to maintain good yield performance under climatic variability and extremes is limited, but diversity in responses to critical weather events can effectively enhance climate resilience. Therefore, a set of cultivars with diverse responses to critical weather conditions is prerequisite to promoting crop climate resilience.


The authors stress that the need for climate resilience of staple food crops such as wheat must be better articulated. Increased awareness could foster governance of resilience through research and breeding programmes, incentives and regulation.



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Exposure To Secondhand Smoke And Arrhythmogenic Cardiac Alternans In A Mouse Model

Continuous indoor exposure to second-hand tobacco smoke triggers changes in the heart's electrical activity, known as cardiac alternans, that can predict cardiac arrhythmia and sudden cardiac death, a new study from UC Davis Health researchers shows.

The authors believe the study, conducted in mice, suggests that second-hand smoke exposure alters cells that regulate how the heart beats. Their work also expands overall knowledge of the effects of tobacco smoke on cardiac function in nonsmokers, something that receives more limited attention in research.


"As tobacco use continues to decrease, research on its effects among nonusers also is declining," said lead author Crystal Ripplinger, associate professor of pharmacology at UC Davis Health.

"Smoking is still a leading cause of preventable illness in the U.S., and bystanders are still exposed to smoking in cars, homes, casinos and when they travel to places with fewer tobacco-smoke protections," Ripplinger added. "It's important to continually define the health effects of those unintended exposures."


Unlike previous research, the study is the first to examine cellular changes in heart tissue in response to ambient tobacco smoke, Ripplinger said. Another distinction is that it focused on a heart condition other than coronary artery disease (CAD), or plaque buildup and vessel hardening associated with lifestyle and age.

"The link between second-hand tobacco smoke and CAD is well established, however there is little-to-no research on how it influences cellular changes associated with arrhythmia, which may affect individuals with or without CAD," Ripplinger said.


The study was a collaboration between Ripplinger and UC Davis Health investigators Chao-Yin Chen, professor of pharmacology, and Kent Pinkerton, professor of pediatrics and director of the Center for Health and the Environment. Mice were exposed to secondhand tobacco smoke in a chamber specifically designed to test health effects associated with inhaled toxins. The smoke levels were set to be similar to those found in public areas where smokers are present.

Following four, eight and 12 weeks of exposure for six hours a day, five days a week, the animals' hearts were tested using high-speed imaging and electrocardiograms for changes in electrical activity. To test susceptibility to arrhythmias, hearts were paced at fast heart rates. They also were tested for levels of calcium, which regulates heart contraction and contributes to abnormal rhythms. The results were compared to hearts of mice exposed only to filtered air.


The researchers found that hearts from mice exposed to filtered air responded normally, but the hearts from mice exposed to secondhand smoke could not tolerate fast rates, especially at 12 weeks of exposure. They also found that calcium levels in these hearts did not respond quickly enough, causing beat-to-beat instability, or cardiac alternans.

"The high incidence of cardiac alternans is particularly concerning because we know that patients with this condition are at significantly higher risk for arrhythmias and sudden cardiac death," Ripplinger said. "Better understanding of this underlying pathology and determining whether these changes are reversible if exposure stops are important areas for future study."




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A Dendritic Substrate For The Cholinergic Control Of Neocortical Output Neurons

University of Queensland researchers have discovered a key mechanism in the brain that may underlie our ability to rapidly focus attention.

Our brains are continuously bombarded with information from the senses, yet our level of vigilance to such input varies, allowing us to selectively focus on one conversation and not another.


Professor Stephen Williams of the Queensland Brain Institute at UQ explains, "If we want to give our full concentration, something happens in the brain to enable us to focus and filter out distractions."

"There must be a mechanism that signals the thing we want to focus on." However, this mechanism is not well understood, he says.

Research has shown that the electrical activity of the neocortex of the brain changes when we focus our attention. Neurons stop signalling in sync with one another and start firing out of sync.


This is helpful, says Williams, because it allows individual neurons to respond to sensory information in different ways. Thus, you can focus on a car speeding down the road or on what a friend is saying in a crowded room.

It's known that the cholinergic system in the brain plays an important role in triggering this desynchronization.

The cholinergic system consists of clusters of special neurons that synthesise and release a signalling molecule called acetylcholine, he explains, and these clusters make far-reaching connections throughout the brain.


Not only does this cholinergic system act like a master switch, but mounting evidence suggests it also enables the brain to identify which sensory input is the most salient—i.e. worthy of attention—at any given moment and then shine a spotlight on that input.

"The cholinergic system broadcasts to the brain, 'this thing is really important to be vigilant to'," says Williams. He adds that the cholinergic system has been proposed to have a far-reaching impact on our cognitive abilities. "Destruction of the cholinergic system in animals profoundly degrades cognition, and the formation of memory," he says.


"Importantly, in humans, progressive degeneration of the cholinergic system occurs in devastating diseases that blunt cognition and memory, such as Alzheimer's disease."

But precisely which neurons in the cortex are being targeted by this master switch and how it's able to influence their function was unknown. 

Williams and QBI researcher Lee Fletcher wondered if layer 5 B-pyramidal neurons, the 'output' neurons of the neocortex, might be involved because they are intimately involved in how we perceive the world.


"The output neurons of the neocortex perform computations that are thought to underlie our perception of the world," says Williams. Williams and Fletcher wanted to know if the cholinergic system is able to influence the activity of these output neurons.

Using a technique called optogenetics, they modified neurons in the cholinergic system in the brains of mice so that they could be activated with a flash of blue light, triggering a sudden release of acetylcholine.


This allowed the researchers to closely monitor the interaction between the cholinergic system and the output neurons.They discovered that if the output neurons were not currently active, not much happened.

But when those neurons received excitatory input to their dendrites, the cholinergic system was able to massively increase their activity. "It's as if the cholinergic system has given a 'go' signal," says Fletcher, enabling the output neurons of the neocortex to powerfully respond.


Importantly, this change was selective, and only apparent when excitatory input was being processed in the dendrites of the 'output' neurons. "We have known for some time that the dendrites of the output neurons of the neocortex only become active when animals are actively performing a behaviour and that this activity is correlated with perception and task performance," says Williams.

This new work demonstrates that the cholinergic system is critical to this transition in mice and rats, allowing the output neurons to perform computations in a state-dependent manner.

"We suggest that this switch also occurs in the human neocortex, allowing us to rapidly switch our state of vigilance and attention," says Williams.


"Our work, therefore, provides important insight into how the progressive degeneration of the cholinergic system in disease blunts human cognition."



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Exercise-Induced Changes In Visceral Adipose Tissue Mass Are Regulated By IL-6 Signaling: A Randomized Controlled Trial

Some of you may have made a New Year's resolution to hit the gym to tackle that annoying belly fat. But have you ever wondered how physical activity produces this desired effect? A signaling molecule called interleukin-6 plays a critical role in this process, researchers report December 27 in the journal Cell Metabolism.

As expected, a 12-week intervention consisting of bicycle exercise decreased visceral abdominal fat in obese adults. But remarkably, this effect was abolished in participants who were also treated with tocilizumab, a drug that blocks interleukin-6 signaling and is currently approved for the treatment of rheumatoid arthritis. Moreover, tocilizumab treatment increased cholesterol levels regardless of physical activity.


"The take home for the general audience is 'do exercise,'" says first author Anne-Sophie Wedell-Neergaard of the University of Copenhagen. "We all know that exercise promotes better health, and now we also know that regular exercise training reduces abdominal fat mass and thereby potentially also the risk of developing cardio-metabolic diseases."

Abdominal fat is associated with an increased risk of not only cardio-metabolic disease, but also cancer, dementia, and all-cause mortality. Physical activity reduces visceral fat tissue, which surrounds internal organs in the abdominal cavity, but the underlying mechanisms have not been clear. Some researchers have proposed that a "fight-or-flight" hormone called epinephrine mediates this effect. But Wedell-Neergaard and co-senior study author Helga Ellingsgaard of the University of Copenhagen suspected that interleukin-6 could also play an important role because it regulates energy metabolism, stimulates the breakdown of fats in healthy people, and is released from skeletal muscle during exercise.


To test this idea, the researchers carried out a 12-week, single-center trial in which they randomly assigned abdominally obese adults to four groups. A total of 53 participants received intravenous infusions of either tocilizumab or saline as a placebo every four weeks, combined with no exercise or a bicycle routine consisting of several 45-minute sessions each week. The researchers used magnetic resonance imaging to assess visceral fat tissue mass at the beginning and end of the study.

In the placebo groups, exercise reduced visceral fat tissue mass by an average of 225 grams, or 8 percent, compared with no exercise. But tocilizumab treatment eliminated this effect. In the exercise groups, tocilizumab also increased visceral fat tissue mass by approximately 278 grams compared with placebo. In addition, tocilizumab increased total cholesterol and "bad" low-density-lipoprotein (LDL) cholesterol compared with placebo, in both the exercise and no-exercise groups. "To our knowledge, this is the first study to show that interleukin-6 has a physiological role in regulating visceral fat mass in humans," Wedell-Neergaard says.


The authors note that the study was exploratory and not intended to evaluate a given treatment in a clinical setting. To complicate matters, interleukin-6 can have seemingly opposite effects on inflammation, depending on the context. For example, chronic low-grade elevations of interleukin-6 are seen in patients with severe obesity, type 2 diabetes, and cardiovascular disease. "The signaling pathways in immune cells versus muscle cells differ substantially, resulting in pro-inflammatory and anti-inflammatory actions, so interleukin-6 may act differently in healthy and diseased people," Wedell-Neergaard explains.

In future studies, the researchers will test the possibility that interleukin-6 affects whether fats or carbohydrates are used to generate energy under various conditions. They will also investigate whether more interleukin-6, potentially given as an injection, reduces visceral fat mass on its own. "We need a more in-depth understanding of this role of interleukin-6 in order to discuss its implications," Wedell-Neergaard says.


In the meantime, the authors have some practical holiday exercise tips. "It is important to stress that when you start exercising, you may increase body weight due to increased muscle mass," Wedell-Neergaard says. "So, in addition to measuring your overall body weight, it would be useful, and maybe more importantly, to measure waist circumference to keep track of the loss of visceral fat mass and to stay motivated."



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Discovery Of TeV γ-ray Emission From The Neighbourhood Of The Supernova Remnant G24.7+0.6 By MAGIC

Using MAGIC telescopes and NASA's Fermi spacecraft, an international team of astronomers has discovered a new source of very high energy gamma-ray emission around the supernova remnant (SNR) G24.7+0.6. The detection of the new source, designated MAGIC J1835–069, is detailed in a paper published December 12 on the arXiv pre-print server.

Supernova remnants are basically leftovers of massive stars that ended their lives in huge explosions called supernovae. Astronomers generally distinguish three types of SNRs, one of which is the composite SNR—these having rapidly expanding shells from the supernova blast wave accompanied by wind nebulae powered by young pulsars formed in the explosions.


Observations show that composite SNRs are known to accelerate particles to very high energies (VHE), up to hundreds of TeV or beyond, in their expanding shocks or the relativistic wind surrounding the energetic pulsar. Therefore, such objects are excellent targets for observations focused on finding new sources of VHE emission.

Located about 16,300 light years away, SNR G24.7+0.6 is an example of a middle-aged (around 9,500 years old) radio and gamma-ray composite SNR. A group of astronomers have carried out a study of this remnant using the MAGIC (Major Atmospheric Gamma Imaging Cherenkov Telescopes) system at the Roque de los Muchachos Observatory in the Canary Islands and the Large Area Telescope (LAT) onboard NASA's Fermi Gamma-ray Space Telescope.


Data provided by these telescopes allowed the team to identify a VHE emission from an extended source located 0.34 degrees away from the centre of G24.7+0.6, which received designation MAGIC J1835–069.

"In this paper, we study the interesting region centred around SNR G24.7+0.6 with Fermi-LAT in the energy range between 60 MeV and 500 GeV. We also explore with the MAGIC telescopes the region around it to investigate the spectral behaviour above 150 GeV in order to constrain the emission region observed by Fermi-LAT around the SNR," the researchers wrote in the paper.


The emission from MAGIC J1835–069 was found at energies above 150 GeV and has been detected up to 5 TeV. The spectrum of this source is well-represented by a power-law function with a spectral index of 2.74.

The emission from MAGIC J1835–069 also has a projected size of approximately 98 light years and showcases an extended morphology. The newly found source lies between two known extended sources detected above 10 GeV by Fermi-LAT, namely FGES J1836.5–0652 and the FGES J1834.1– 0706.


The origin of VHE gamma-ray emission from MAGIC J1835–069 remains uncertain due to the complexity of the neighbouring region of G24.7+0.6. However, the authors of the paper suggest that it could be explained by cosmic rays accelerated within the remnant interacting via proton-proton collisions with the carbon monoxide-rich surrounding medium.

"The detected gamma-ray emission can be interpreted as the results of proton-proton interaction between the supernova and the CO-rich surrounding," the researchers concluded.




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Beyond The Molecular movie: Dynamics of bands and bonds during a photoinduced phase transition

In a recent publication in Science, researchers at the University of Paderborn and the Fritz Haber Institute Berlin demonstrated their ability to observe electrons' movements during a chemical reaction. Researchers have long studied the atomic-scale processes that govern chemical reactions, but were never before able to observe electron motions as they happened.

Electrons exist on the smallest scales, being less than one quadrillionth of a meter in diameter and orbiting an atom at femtosecond speeds (one quadrillionth of a second). Experimenters interested in observing electron behaviour use laser pulses to interact with the electrons. They can calculate the energy and momentum of the electrons by analysing the properties of the electrons kicked out of the probe by the laser light.

The challenge for researchers is recording events that are taking place on a femtosecond scale—they must first excite a system with a laser pulse, then watch the next few femtoseconds. Then, they send a second laser pulse with a short time delay of a few femtoseconds. Achieving this level of resolution is difficult, as femtoseconds are extremely short—light can travel 300,000 kilometers in one second, but just 300 nanometers in one femtosecond.

After being excited with the first laser pulse, the atoms' valence electrons—electrons on the outside of an atom that are candidates for helping form chemical bonds—may re-arrange to form new chemical bonds, resulting in new molecules. Because of the speed and scale of these interactions, though, researchers have only hypothesized how this re-arrangement takes place.

In addition to experimental methods, high-performance computing (HPC) has become an increasingly important tool for understanding these atomic-level interactions, verifying experimental observations, and studying electron behaviour during a chemical reaction in more detail. A University of Paderborn group led by Prof. Dr. Wolf Gero Schmidt has been collaborating with physicists and chemists to complement experiments with computational models.

In order to better understand electrons' behaviour during a chemical reaction, Schmidt and his collaborators have been using supercomputing resources at the High-Performance Computing Center Stuttgart (HLRS) to model this phenomenon. "The experimental group at the Fritz Haber Institute came to us about this research, and we had actually already done the simulation," Schmidt said. "In this case, theory was ahead of experiment, as we had made a prediction and the experiment confirmed it."

Last year, Schmidt's group partnered with experimentalists from the University of Duisburg-Essen to excite an atomic-scale system and observe photo-induced phase transitions (PIPTs) in real time. Phase transitions—when a substance changes from one physical state to another, such as water changing to ice—are important in studying and designing materials, as a substance's properties may change wildly depending on the state it is in.

For example, the team found that when excited with a laser pulse, indium-based nanoscale wires would essentially change from an insulator into an electrical conductor. These indium wires, while not necessarily of immediate technological interest for electronic applications, serve as a good test case and a solid basis for verifying simulations with experiments.

This year, the team wanted to take what it had learned about the indium wires previously and study chemical reactions on an even more fundamental level—it wanted to track how the constituent electrons behave after being excited by a laser pulse. "Last year, we published a Nature article that demonstrated the measurement of the atomic movement on this scale," Schmidt said. "We could show how the atoms moved during the chemical reaction. This year, we were even able to monitor the electrons while the reaction took place."

Figuratively speaking, electrons serve as the glue that chemically binds atoms together. However, a laser pulse can kick out an electron, creating what researchers call a "photohole." These photoholes only last for several femtoseconds, but may lead to the breaking of chemical bonds and the formation of new bonds. When the indium nanowire is hit with a laser pulse, the system forms a metallic bond, which explains its phase change into an electrical conductor.

Supercomputing simulations allow researchers to put the electrons' paths in motion, ultimately helping them study the full reaction "pathway." Researchers run first principles simulations, meaning that they start with no assumptions about how an atomic system works, then computationally model atoms and their electrons under the experimental conditions. These types of intensive, first principles calculations require leading-edge supercomputing resources, such as those provided through the Gauss Centre for Supercomputing at HLRS.

Between its former work and its current project, the team now better understands the important role that photoholes play in shaping how energy is distributed across a system, ultimately giving the researchers a reliable computational method with which to simulate extremely fast phase transitions.

The team's current simulations consist of around 1,000 atoms, which, while small, allows them to get a representative sample of how a system's atoms and their constituent electrons interact. The Paderborn group got help from the HLRS team in optimizing its code, allowing it to run efficiently on up to 10,000 cores in parallel. Schmidt explained that while the overall research would benefit from growing the system size to the order of 10,000 atoms, the next phase of the team's work is to work on more complex systems.

"The current research is a complex calculation, but a simple system," he said. "Our next step is to develop this research as it relates to photocatalysts or systems that are relevant for large-scale energy production—we want to apply this to a real system." By better understanding electrons' behaviours at the atomic level, researchers aim to design better materials for converting, transporting, and storing energy.

Source: Science Nature
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A Novel Alkaliphilic Streptomyces Inhibits ESKAPE Pathogens

Researchers analysing soil from Ireland long thought to have medicinal properties have discovered that it contains a previously unknown strain of bacteria which is effective against four of the top six superbugs that are resistant to antibiotics, including MRSA.

Antibiotic-resistant superbugs could kill up to 1.3 million people in Europe by 2050, according to recent research.


The World Health Organisation (WHO) describes the problem as "one of the biggest threats to global health, food security, and development today".

The new strain of bacteria was discovered by a team based in Swansea University Medical School, made up of researchers from Wales, Brazil, Iraq and Northern Ireland.

They have named the new strain Streptomyces sp. myrophorea. The soil they analysed originated from an area of Fermanagh, Northern Ireland, which is known as the Boho Highlands. It is an area of alkaline grassland and the soil is reputed to have healing properties.


The search for replacement antibiotics to combat multi-resistance has prompted researchers to explore new sources, including folk medicines: a field of study known as ethnopharmacology. They are also focusing on environments where well-known antibiotic producers like Streptomyces can be found.

One of the research team, Dr. Gerry Quinn, a previous resident of Boho, County Fermanagh, had been aware of the healing traditions of the area for many years.

Traditionally a small amount of soil was wrapped up in cotton cloth and used to heal many ailments including toothache, throat and neck infections. Interestingly, this area was previously occupied by the Druids, around 1500 years ago, and Neolithic people 4000 years ago.


The main findings of the research were that the newly-identified strain of Streptomyces:


  • Inhibited the growth of four of the top six multi-resistant pathogens identified by the WHO as being responsible for healthcare-associated infections: Vancomycin resistant Enterococcus faecium (VRE), methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumonia, and Carbenepenem-resistant Acinetobacter baumanii




  • Inhibited both gram positive and gram negative bacteria, which differ in the structure of their cell wall; usually gram negative bacteria are more resistant to antibiotics




    • It is not yet clear which component of the new strain prevents the growth of the pathogens, but the team are already investigating this.

    Professor Paul Dyson of Swansea University Medical School said: "This new strain of bacteria is effective against 4 of the top 6 pathogens that are resistant to antibiotics, including MRSA. Our discovery is an important step forward in the fight against antibiotic resistance.


    Our results show that folklore and traditional medicines are worth investigating in the search for new antibiotics. Scientists, historians and archaeologists can all have something to contribute to this task. It seems that part of the answer to this very modern problem might lie in the wisdom of the past."

    Dr. Gerry Quinn from the research team said: "The discovery of antimicrobial substances from Streptomyces sp.myrophorea will help in our search for new drugs to treat multi-resistant bacteria, the cause of many dangerous and lethal infections.


    We will now concentrate on the purification and identification of these antibiotics. We have also discovered additional antibacterial organisms from the same soil cure which may cover a broader spectrum of multi-resistant pathogens."



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    Whale Rover Moving Along The Surface Of Sperm Whale

    A team of researchers at Yamagata University and Teikyo University of Science, in Japan, have recently developed a new roving biologger, or whale rover, which can travel along a sperm whale's body surface and collect valuable behavioural data. Biologging entails the biological tracking of individual animals, typically by attaching small dataloggers directly to their bodies. It can be a very effective way of unfolding the mysteries of animal life, by collecting data and observations related to an animal's behaviour, motion, and biology.

    "Our project started in 2012. In the previous year, a marine zoologist, Prof. Kyoichi Mori, had consulted with me on how we could tackle a current problem," Prof. Yuichi Tsumaki, one of the researchers who carried out the study, told TechXplore. "We were eager to capture video data of preying sperm whales, because no one knows what happens when a sperm whale eats a giant squid."


    Traditionally, animals are studied by visually observing their behaviour, habits and biology. However, these visual observation methods are difficult to implement when it comes to researching the ecology of marine animals, particularly those inhabiting the depths of the sea or ocean.

    Biologging techniques have significantly improved the ability of researchers to study these animals in their natural habitat. In recent years, advancements in electronic technology have led to the development of a wide range of biologgers of different sizes and weights.


    Biologgers allow researchers to collect key information about marine animals, including their 3-D motion trajectory, diving depth, and swimming speed, as well as physiological data such as body temperature and electrocardiogram readings. Some of these biologgers are also equipped with cameras and can thus collect unprecedented images or videos that depict an animal's predatory or social behaviour.

    "We wanted to attach a camera logger around the mouth area, with the main objective of shooting footage of a sperm whale eating a giant squid," Tsumaki explained. "To achieve this, we developed a whale rover that has potential to reach the animal's mouth area. The whale rover is based on the 'environment driven concept' proposed in our previous work, in the context of asteroid exploration. To locomote in harsh environments with minimum mechanisms, the energy of the environment is utilized for locomotion. This system should ideally achieve both compactness and mobility at a depth of over 1000 m."


    The whale rover developed by Tsumaki and his colleagues improves the visibility of a sperm whale's mouth area as it moves across the deep sea, travelling along the animal's body surface using robotic technology. An environmentally driven concept devised by the researchers allows the biologger to achieve adsorption motion, using the water current generated by a swimming whale as a power source, without relying on a distinct central processing unit (CPU) and battery.

    "We reduced the size by concentrating the valve system, and increased the adsorption force by increasing the suction cup size and flexibility," Kosuke Tsuchiya, another researcher involved in the study, told TechXplore. "We have achieved adsorption walking motion at a depth of 500 m using only the water flow as the power source. Our technology has the potential to be used in the area of not only biologging but also underwater robot applications, such as inspection of submarine cable systems or inspection of the bottom of large vessels."


    The researchers tested their innovative and environmentally driven whale rover in several field and laboratory experiments. They found that it could successfully travel across a flat acrylic surface at a depth of almost 500 m, which confirms its applicability in deep-sea environments.

    In water tank lab experiments, the biologger could travel across a 1.5 m radius curved acrylic surface, with a 46% success rate. These preliminary findings suggest that the technology might not yet be applied in real-world scenarios, where it would need to travel longer distances. However, overall the biologger yielded highly promising results, showing great potential for a variety of underwater applications.


    "Currently, we are designing a new prototype with new suction cup arrangement, measuring equipment and float," Tsumaki said. "These features should allow us to attach the prototype to a sperm whale's body surface for the first time. In the near future, we will conduct experiments in the ocean around the Ogasawara islands."



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