Brain

New research suggests that graphene - made in a specific way- could be used to make more durable hydrogen fuel cells for cars.

In the study, published today in the journal Nanoscale, scientists produced graphene via a special, scalable technique and used it to develop hydrogen fuel cell catalysts. The research team, involving scientists from Queen Mary University of London and University College London (UCL), showed that this new type of graphene-based catalyst was more durable than commercially available catalysts and matched their performance.

Hydrogen fuel cells convert chemical energy into electrical power by combining hydrogen and oxygen with the aid of catalysts. As the only by-product of the reaction is water, they provide an efficient and environmentally friendly power source.

Platinum is the most widely used catalyst for these fuel cells, but its high cost is a big problem for the commercialisation of hydrogen fuel cells. To address this issue, commercial catalysts are typically made by decorating tiny nanoparticles of platinum onto a cheaper carbon support, however the poor durability of the material greatly reduces the lifetime of current fuel cells.

Previous research has suggested graphene could be an ideal support material for fuel cells due to its corrosion resistance, high surface area and high conductivity. However, the graphene used in the majority of experiments to-date contains many defects, meaning that the predicted improved resistance has not yet been achieved.

The technique described in the study produces high-quality graphene decorated with platinum nanoparticles in a one-pot synthesis. This process could be scaled up for mass production, opening up the use of graphene-based catalysts for widespread energy applications.

Professor Dan Brett, Professor of Electrochemical Engineering at UCL, said: "Satisfying global energy demands without damaging the environment is one of the great modern challenges. Hydrogen fuel cells can provide cleaner energy and are already used in some cars as an alternative to petrol or diesel. However, a big barrier to their widespread commercialisation is the ability for catalysts to withstand extensive cycling required for their use in energy applications. We've shown that by using graphene instead of the typical amorphous carbon as a support material we can create ultra-durable catalysts."

The researchers confirmed the durability of the graphene-based catalyst using a type of test based on those recommended by the US Department of Energy (DoE), known as accelerated stress tests. Accelerated stress tests deliberately stress the catalyst rapidly over many cycles in a short space of time, allowing scientists to assess the stability of new materials without having to use them in an operational fuel cell over a period of months or years.

Using these tests, the scientists showed that loss in activity over the same testing period was around 30 per cent lower in the newly developed graphene-based catalyst, compared with commercial catalysts.

Gyen Ming Angel, PhD student and lead author of the study, from UCL, said: "The DoE sets tests and targets for fuel cell durability, with one accelerated stress test to simulate normal operating conditions and one to simulate the high voltages experienced when starting up and shutting down the fuel cell. Most research studies in the graphene space only evaluate using one of the recommended tests. However, since we have high-quality graphene in our material, we have managed to achieve high durability in both tests and under long testing periods, which is important for the future commercialisation of these materials. We look forward to incorporating our new catalyst into commercial technology and realising the advantages of longer-life fuel cells."

Graphene is made from a single layer of carbon atoms arranged in a hexagonal lattice. Despite its relatively simple structure, graphene is thought to have remarkable properties including high electrical conductivity, high transparency and high flexibility.

Dr. Patrick Cullen, Lecturer in Renewable Energy from Queen Mary University of London, said: "Over the years, there's been a lot of hype around graphene and the vast number of promising applications for this material. However, the research community is still waiting for its full potential to be realised, and this has led to some negativity around this proposed 'wonder material'. This view isn't helped by the fact that many research studies on graphene use defective versions of graphene. We hope that this paper can restore faith in graphene and show that this material holds great potential for improving technology, like fuel cells, now and in the future."

Crown-of-thorns starfish are renowned for eating coral and destroying coral reefs--but when juvenile crown-of-thorns first settle in reef environments they start out by eating rock-hard coralline algae. In a new study, Jennifer Wilmes and her colleagues compared the growth between juvenile crown-of-thorns starfish that switch diets early after settlement (within six months) versus those that continue to feed on coralline algae for up to a year.

The authors found that juveniles that start eating corals earlier exhibit enhanced growth rates for longer and will ultimately get much bigger. Larger crown-of-thorns starfish have much greater reproductive capacity and consume coral at higher rates. The variation in early development can have important consequences not only for crown-of-thorns starfish population dynamics, but for their impacts on coral reef ecosystems.

The study concludes: "Understanding the mechanisms that determine population replenishment is essential to develop effective early management intervention strategies. Failing to develop well-informed decision tools risks to produce counterproductive management outcomes and could in the worst case contribute to the collapse of the system itself, with potentially devastating and irreversible impacts on reef ecosystems."

WASHINGTON, July 21, 2020 -- The production of biodiesel from vegetable oil has been around for more than 150 years, and the approach significantly reduces several pollutants associated with burning fossil fuels. Vegetable oils, however, can be notoriously difficult to use in an engine, providing low power output and release of unique toxic byproducts.

Brazilian researchers demonstrated a new chemical approach for producing biodiesel from domestic cooking oil waste by using hydroxide lithium mixed with either sodium hydroxides or potassium hydroxides as catalysts. Their work, published in the Journal of Renewable and Sustainable Energy, by AIP Publishing, could enable future studies related to the use of lithium from waste lithium ion batteries.

The work marks one of the first times lithium has been used for such purposes. Author Gilberto Maia de Brito said green engineering can yield solutions for a variety of problems at the same time.

"The results achieved in this work will make it possible to expand the use of new types of metallic catalysts to a higher level, such as lithium, applied to the production of biodiesel," he said. "Before, in practice, these were just restricted to sodium hydroxide and potassium hydroxide."

The group's technique draws on one proposed solution for creating biodiesel, called transesterification, which can yield fuel in a matter of minutes at room temperature.

The researchers collected waste cooking oil samples from fast food restaurants and homes, some of the biggest sources of waste disposed of inappropriately, and lithium hydroxide from lithium ion battery waste.

When catalyzed by the mixture of metal hydroxides, the transesterification reaction split the cooking oil into a biodiesel layer and a layer of glycerol, which itself can be used in a variety of ways such as producing food sweeteners, alleviating certain skin conditions and acting as a main reactant in making antifreeze.

With the right proportions of catalysts, the group was able to produce biodiesel with an average yield of 90%. They analyzed the biodiesel, using techniques ranging from infrared spectroscopy to chromatography to nuclear magnetic resonance studies, to assess the purity of their fuel.

"We were surprised that what came out was not only some results, but actually very good results related to the yield production," Maia de Brito said. "The fast phase separation and the main chemistry and physics properties of that biodiesel produced from lithium were also surprising."

Maia de Brito hopes to continue finding new ways to recover lithium from waste and use it to facilitate biofuel production even further.

Topological insulators have been an exciting field of research with fundamental interest as well as practical applications such as robust transport of electrons and light, and topological quantum computing. The hallmark of such conventional topological insulators is the presence of conducting boundary modes which have one dimension lower than the insulating bulk system that hosts them - for example a one-dimensional edge mode at the boundary of a two-dimensional system, or a two-dimensional surface state at the boundary of a three-dimensional system. In 2017, scientists generalized this concept to predict a new phase of matter called higher-order topological insulators (HOTIs), which support "corner modes" - e.g. a zero-dimensional mode in a two-dimensional system. Since then, there have been several experimental demonstrations of this new HOTI phase, most of which involve complicated geometries. Moreover, these previous systems are fixed - i.e. one cannot dynamically switch or tune their higher-order topological behavior once they are fabricated.

In a new paper published in Light Science & Application, a team of scientists, led by Professor Shanhui Fan from Stanford University, USA, and co-workers have proposed a way to realize such higher-order topology and corner states using an emerging concept called "synthetic dimensions", in simpler structures and in a dynamically tunable way. Usually, particles like photons and electrons are assumed to move along the three directions - x, y and z, or length, width and depth. What if one could imagine the motion of photons beyond these three "real" directions? The team calls these extra directions of motion as synthetic dimensions.

To make this conceptual leap from the three "real" dimensions to synthetic dimensions, they harnessed internal properties inherent to all photons - the frequency or color of light, which determines how much energy a photon carries. Previous work from the Stanford team and other groups have demonstrated conventional (first-order) topological phases using this concept of synthetic dimensions, including intriguing physical phenomena such as the quantum Hall effect. However, higher-order topology had remained beyond the reach of synthetic dimensions till now, although the high-dimensional nature of HOTIs is very well suited to the idea of synthetic dimensions.

To construct the higher-order topological insulator, the researchers propose using a set of ring resonators which are coupled to each other in a specific arrangement Each ring resonator is essentially a thin wire of a transparent material looped on itself, such that a photon can go around the loop many times. A pair of two identical ring resonators together forms a 'photonic molecule', just like two hydrogen atoms form a diatomic molecule. By arranging multiple such photonic molecules along a line, a second-order topological insulator for photons can be formed. Just like in real dimensions one can control whether a photon moves to the right or the left (say in the x direction), the ring resonator can control in synthetic dimensions whether a photon moves up or down in frequency. Such movement in frequency is achieved with another photonic component called a modulator - a device that can change the material's refractive index at high speeds, making them essential to today's optical telecommunications networks.

Next, the team predicts how the hallmark of higher-order topology - the corner modes - can be seen in this system by sending specific frequencies of laser light into the set of photonic molecules. For these corner modes, light is confined to the corner of the two-dimensional structure consisting of one real dimension and one synthetic frequency dimension, and there is almost no light in the rest of the structure.

"A big advantage of synthetic dimensions is the flexibility with which various knobs can be controlled to tune system parameters. By controlling the strength and timing of the electronic signal applied to the modulators in the photonic molecules, we showed how these corner modes could be turned on and off. In other words, you can switch the system from having higher-order topology to having no topology, dynamically. This capability is unmatched in typical electronic or photonic systems," the authors say.

With synthetic dimensions, one can think of building very high-dimensional topological insulators, which are difficult to build or even imagine in real space because we live in a three-dimensional world. As an example, the team constructs a fourth-order topological insulator in a four-dimensional system, which has not been predicted before since it is beyond the purview of three-dimensional real space.

"Our recipes lay out how to use synthetic dimensions to implement very complicated high-dimensional phenomena, including extremely-high-order topological insulators and other exotic phases of light and matter, in much simpler systems, and dynamically control their properties almost at will. Experimental realizations of this concept are well within the reach of current state-of-the-art photonic technology," the scientists add.

Topological insulators are a new phase of matter featured by their insulating bulk and perfectly conducting edges. They have been at the forefront of condensed matter physics for the past decade and more recently inspired the emergence of topological phases in many classical-wave systems, such as photonics and acoustics. Up to date, all studies of topological insulators have explored systems in integer dimensions (physically, 2D or 3D) with a well-defined bulk and edges. However, the physical dimensions do not always define the dimensions in which a system evolves: some structures have a noninteger (fractal) dimension, despite being in a 2D or 3D realm.

In a new paper published in Light Science & Application, a team of scientists, led by Professor Mordechai Segev from Physics Department and Solid State Institute, Technion-Israel Institute of Technology, Israel, and co-workers have developed the photonic Floquet topological insulator in a periodically driven fractal lattice. This lattice relies on a fractal photonic crystal [the Sierpinski gasket (SG)] consisting of evanescently coupled helical waveguides, which can be realized by femtosecond-laser-writing technology. They calculate the topological Floquet spectrum and show the existence of topological edge states corresponding to real-space Chern number 1. The simulations of the edge states show that wavepackets made up of topological edge states can propagate along the outer and inner edges without penetration into the 'bulk' and without backscattering even in the presence of disorder and sharp corners.

"Our results suggest a wealth of new kinds of topological systems and new applications, such as using topological robustness combined with the enhanced sensitivity of fractal systems for sensing and, in non-Hermitian settings, topological insulator lasers in fractal dimensions." the scientists forecast.

The unusual dark greenish and glistening "gel-like" substance in a crater on the far side of the moon has attracted widespread interest following its discovery by the Chang'e-4 rover in July 2019.

A research team led by Prof. DI Kaichang from the Aerospace Information Research Institute (AIR) of the Chinese Academy of Sciences and their collaborators analyzed the substance in detail by using multiple datasets from the rover's panoramic camera (Pancam), hazard avoidance camera (Hazcam), and the visible and near-infrared spectrometer (VNIS).

The researchers found that the unusual substance is actually an impact melt breccia, and the provenance of the rover measured surrounding regolith might originate from a differentiated melt pool or from a suite of igneous rocks. Their findings were published in Earth and Planetary Science Letters.

China's Chang'e-4 probe, including a lander and a rover, successfully touched down within the 185-km-wide Von Kármán crater inside the South Pole-Aitken (SPA) basin on January 3, 2019, making the first-ever soft landing on the lunar far side.

The gel-like substance was discovered in a crater (Fig. 1) during the eighth lunar day of the rover's mission. Detailed measurements on the breccia and surrounding regolith were conducted during the ninth lunar day.

The discovered breccia, measuring 52 by 16 centimeters, resembles the lunar impact melt breccia samples 15466 and 70019 (Fig. 2) returned by the Apollo missions. It was formed by impact-generated welding, cementing and agglutinating of lunar regolith and breccia.

Clods surrounding the breccia-hosting crater were crushed into regolith powders by the rover's wheels (Fig. 3), indicating the regolith may be compacted slightly and becomes blocky and friable.
Hapke model-based spectral unmixing results showed that plagioclase was abundant, and pyroxene and olivine had almost equal fractions, indicating the regolith was likely the weathering products of noritic rocks.

The regolith measured by Chang'e-4 rover was actually a mixture of multiple sources, with ejecta from Finsen crater being primary and possible contributions from Alder crater. Finsen and Alder craters are on the margin of the proposed impact melt pool produced by the SPA basin-forming event. Therefore, the provenance of the regolith might originate from a differentiated melt pool or from a suite of igneous rocks.

Scientists studying brown-throated three-toed sloths, where predators are extinct and food is more accessible, have found that the animals adapt to have a primarily diurnal, or daytime, schedule.

The study was conducted in a highly disturbed section of the Atlantic forest, in Northeastern Brazil. Researchers recorded the sloths' behaviors and circadian rhythm during the course of 29 days. The results, published in the journal Mammalian Biology, present a unique take on the impact of human activity in the area. While deforestation, development, intentional fire setting and nighttime hunting have been detrimental to various tree and animal species, brown-throated three-toed sloths may benefit in shifting from nocturnal tendencies to becoming primarily daytime active.

"These environmental disturbances are in no way an ideal scenario from a conservation perspective but the results -- fewer predators, easier access to primary food sources -- clearly had a positive impact based on our observations," said Giles Duffield, associate professor in the Department of Biological Sciences at the University of Notre Dame, and a co-author of the study. "With less competition for food and fewer predators these animals developed a more synchronous pattern of activity."

Previous studies have focused sloth activity in undisturbed forests. The research, led by Antonio Rossano Mendes Pontes at the National Institute of Amazonian Research, is unique in that researchers not only monitored sloths in a highly disturbed setting but their behavior -- rest, travel, movement, feeding and grooming -- was observed over a complete 24-hour cycle.

"In all other studies, sloths have been found to be nocturnal or cathemeral," Duffield said. "We did not expect to see such clear and distinct diurnal behavior."

Sloths spend a majority of their time at rest -- up to 90 percent in some cases. A number of factors can influence a sloth's tendency toward diurnal or nocturnal activity, including temperature, competition and the threat of predators. Rest was still the dominant activity, even in a highly disturbed environment. The sloths spent an average of 75 percent of their time resting. Females rested significantly more than the males and infants rested 79 percent of the time on average. Peak activity took place in the early morning and late afternoon hours.

There is no preserved land left within the Atlantic forest, according to the study. An estimated 98 percent of its woodland has been lost, so researchers can't compare activity between highly disturbed and undisturbed sections of the forest. For the same reason, the study asserts the assumption that the daytime activity observed by this group of sloths is an adaptive response to changes in their environment.

While found in a few unique cases in nature, "it's generally rare to observe such flexibility in an organism that allows it to switch from predominately nocturnal to daytime active," Duffield said. "These results highlight that a more variable or nocturnal activity pattern might be a strategy that improves chances of survival in a more challenging environment, one with predators such as eagles and large snakes, heavier competition for food sources produced by other herbivores, and where the sloth has to move around more to find its preferred food. It's ironic, but these results suggest that when conditions are 'easier' for the iconic slow-moving sloth, as we find in this disturbed forest habitat, it reverses the time of its preferred activity within the 24-hour day.

Researchers from Kazan Federal University, Texas A&M University and Institute of Applied Physics (Russian Academy of Sciences) found ways to direct high frequency gamma radiation by means of acoustics.

The paper describes an optical "switch" - a device able to let through or stop gamma quanta by switching the acoustic field. Basically, the mechanism makes iron "transparent" for gamma rays when needed.

Mossbauer Spectroscopy Lab of Kazan Federal University showed acoustically induced transparency of a resonant medium for gamma radiation in an experiment. The essence of this phenomenon lies in the transformation of the spectrum of the absorption line into a comb structure consisting of satellite lines spaced from the main line by the frequency of the acoustic field. For the experiment, gamma quanta with an energy of 14.4 keV were used, which are emitted during the decay of the excited state of the iron-57 nucleus.

"By acting on the absorber containing the Fe-57 nuclei with the help of a piezoelectric transducer, it was possible to achieve for the optically dense absorber to become transparent to resonant gamma rays. The absorber was attached to a piezoelectric transducer, which vibrated at a certain frequency and amplitude. At an oscillation amplitude corresponding to a modulation index of 2.4, the absorption of photons with an energy of 14.4 keV was suppressed 148 times," explains Mossbauer Spectroscopy Lab Head Farit Vagizov. "This effect is analogous to the effect of electromagnetically induced transparency in optics, when radiation in one frequency range is used to control electronic transitions of atoms in another frequency range. As you know, the effect of electromagnetically induced transparency in atomic media has a fairly wide area of potential applications: the creation of controlled delay lines, devices for recording and reproducing quantum information, frequency standards in atomic clocks, and much more."

This effect showed that with the help of low-frequency (~10-40 MHz) acoustic excitation, it is possible to control the process of transmission of high-frequency electromagnetic radiation with a frequency of more than 1013 MHz through the resonant medium. This effect may turn out to be useful for controlling the generated radiation on modern synchrotron sources and X-ray lasers, as well as for creating promising quantum devices.

Researchers at Vanderbilt University Medical Center (VUMC) have shown for the first time that when one optic nerve in the eye is damaged, as in glaucoma, the opposite optic nerve comes to the rescue by sharing its metabolic energy.

In doing so, however, the undamaged optic nerve becomes vulnerable to further metabolic stress, which could explain why the neurodegeneration observed in this and other diseases spreads between brain regions.

"This is the first demonstration of metabolic resources being shared between the two eyes and optic nerves," said David Calkins, PhD, Vice Chair of the Department of Ophthalmology and Visual Sciences at VUMC and Director of the Vanderbilt Vision Research Center.

The report by Calkins and colleagues, published Monday in the Proceedings of the National Academy of Sciences, suggests a potential new approach to treating neurodegenerative diseases like glaucoma and Alzheimer's disease by beefing up the metabolic resources of the involved neurons.

Glaucoma, a leading cause of blindness, is caused by sensitivity to ocular pressure, which leads to degeneration of the eye's neural projection to the brain.

Crucial to neuronal health are astrocytes, the star-shaped glial cells that store glycogen and release it as glucose, the fuel that neurons need to function since they do not store their own energy source.

Using positron emission tomography (PET) imaging, which can map the metabolic activity of cells in different tissues, the researchers showed that when one optic nerve was stressed by a rise in intraocular pressure, metabolites including glycogen were transferred from the healthy optic nerve via their crossover point in the brain.

"The energy is transferred up one optic nerve, across the optic chiasm (an X-shaped structure formed by the crossing of the optic nerves) in the brain and back down to the other eye, which is a tremendous distance for metabolites to travel," Calkins said.

"We don't know exactly how it's done," he said.

However, the transfer is dependent on connexin 43 (Cx43), the protein that makes up the gap junctions in astrocytes. Gap junctions are intracellular channels that connect adjacent cells and which permit the exchange of small molecules between them.

When Cx43 was genetically "knocked out" in a mouse model, the energy transfer didn't happen within the astrocyte networks between the two optic nerves.

The transfer phenomenon helps explain the bilateral effects seen in neurodegenerative diseases. Alzheimer's disease, for example, can start in one hemisphere of the brain and travel to the next.

While sharing energy helps the diseased tissue, the tissue that's donating its energy stores becomes more susceptible to subsequent injury. "There's a price to be paid," Calkins said.

"This implies that a way to slow neurodegeneration generally would be to boost metabolic resources in the brain," he said. "One way that can be done is by targeting astrocytes to reprogram them to create and store more metabolites to share with neurons.

Using gene therapy to reprogram neurons in certain diseases of the visual system has been shown to be effective. "What I'm trying to do now is through gene therapy to reprogram astrocytes by using viruses to insert genes into their DNA," he said.

A study by Natalia Maloshonok and Irina Shcheglova, research fellows of the HSE University, examines how and why gender stereotypes can disempower female students, leading to poor academic performance and high dropout rates. According to the study, more than one in three (35%) young women have been led to believe in men's superior mathematical ability.

Women's Share

Gender imbalance starts in secondary school, continues through high school and further increases in university, with few female undergraduates choosing science and engineering as majors. The final stage of this negative selection occurs in the workplace.

In Russia, the proportion of female students in STEM-related undergraduate and specialty courses varies from one-quarter to one-third, depending on the area of study. In 2018, according to the Ministry of Education and Science data, women accounted for just 26% of students in Engineering, Technology and Technical Sciences undergraduate courses, 27% in Computer and Information Sciences courses, almost a third (31%) in Mathematics and Mechanics, and 32% in Physics and Astronomy. This data is consistent with the Organization for Economic Cooperation and Development (OECD) indicators for Russia: at bachelor's level, just 35% of graduates in STEM are women.

Maloshonok and Shcheglova suggest that this imbalance could largely be due to gender stereotypes. In order to test their hypothesis, the researchers analysed data from the Study of Undergraduate Performance (SUPER-test) , an international comparative study of engineering students' educational achievement carried out by HSE in cooperation with Stanford University and others.

More than 2,600 first-year undergraduates were surveyed in the autumn of 2015. In the spring of 2017, dropout data was collected on the same students. The researchers examined data on undergraduates in 17 engineering and computer science majors, including fundamental informatics, applied informatics, mathematics, information systems, software engineering, radio engineering, electronics, laser technology, photonics, and others.

Dropout Paradox

Although some internationally published papers suggest that women are less likely to persist in STEM field majors, while male gender is a predictor of students' intention to persist in the computer science major beyond the introductory course, HSE researchers found the opposite to be true, namely that young men were more likely than young women to drop out from STEM majors, e.g. by 7% (19% versus 12% for women) for engineering and by 5% (22% versus 17%) for computer science.

This may reflect an important distinction between universities in Russia and other countries in terms of their tuition fee systems. In Russia, most students' tuition fees are subsidised by the state, and the most common reason for student dropout is involuntary expulsion for academic failure. In contrast, many students in the U.S. pay for their own tuition, and a significant proportion of those who drop out do so voluntarily.

'The fact that their tuition is subsidised can be a strong incentive for young women to complete their major even if they are dissatisfied with their training and experience as students,' the researchers conclude.

Risk propensity--believed to be higher in young men--may be another factor explaining the gender-based differences in student dropout rates. It has been shown that risk-prone students are more likely to drop out.

It follows from the above that on average, female undergraduates in STEM majors perform better academically than their male counterparts and are more likely to complete their studies. But is it possible to reduce the dropout rates of female students even further? What is the main reason behind their choice to leave: being overwhelmed by the curriculum or something else?

Sadly, gender stereotypes seem to be at play here as well. Not only do they affect young women's interest in exact sciences and the choice of career in STEM, but even more importantly, they can undermine female students' confidence in their ability to compete successfully with men.

Passing through Filters

Many female undergraduates have heard time and again that their mathematical ability is less than that of their male counterparts, often undermining the women's motivation to persist towards a degree in related fields. 'For some young women, this can lead to dropout or to giving up on their chosen career following graduation,' according to the researchers.

'Dropout risks increase for girls who believe that boys have better mathematical ability, and 35% of female students in our sample share this belief,' Shcheglova comments. Her co-author Maloshonok confirms that 'this group of female undergraduates are 57% more likely to drop out than male students.'

Despite research findings which indicate women's better performance in STEM, 'These arguments are usually ignored,' according to the engineer Anna S. 'Even when you are good academically, others may be able to convince you before your final year in university that succeeding in "men's domain" is beyond your ability. Over time, many women decide that they are likely to hit the glass ceiling there anyway, and may be better off elsewhere.'

But where does this 'women cannot succeed at STEM' stereotype come from? In fact, no gender difference in the quality of publications has been found in existing scientific papers authored by men and women worldwide. 'However, for some reason, it is widely believed that ladies do not have a brain for mathematics,' says the physicist Natalya. 'I remember a male fellow-student saying that women were not able to think rationally and did not have the "mathematical clarity of mind." It was the perfect demotivator.' Natalya admits having doubts about her own abilities after hearing that.

The researchers compare these gender stereotypes to a tough filter that far from all women are able to pass. Needless to say, any stereotypes about women's lack of ability in mathematics are totally untrue.

KANSAS CITY, MO--Cavefish may not seem like a big deal. They're small, they live in tucked away places humans rarely go, and they're common enough that you can find them on every continent except Antarctica. But researchers from the Stowers Institute for Medical Research see them as a potential way to understand more about the rise in autoimmune diseases in humans.

"Cavefish present us with an opportunity to ask, 'How does an immune system evolve when there are no parasites?' " explains Robert Peuss, PhD, postdoctoral research associate in the laboratory of Nicolas Rohner, PhD, at the Stowers Institute.

That's because, like cavefish, most humans are now living in environments that are relatively free from parasites. And like cavefish, humans have an innate and an adaptive immune system that protect them from potential parasites. But unlike cavefish, the human immune system sometimes looks for something to attack even when parasites aren't there, while the cavefish have evolved an immune system that seems to act normally even in the absence of parasites.

"One hypothesis is that certain parasites help to balance our immune system responses. In the absence of these parasites, this balance can be disturbed and as a consequence the immune system attacks our own cells in the body," says Peuss. The question of why one person's immune system is affected while another is not is still a question that puzzles many scientists around the world. And we need answers soon! Autoimmune diseases, such as Type 1 diabetes, now affect up to 23.5 million Americans according to the National Institutes of Health, and those numbers are rising.

Advances in modern hygiene and medical treatments have improved health and increased life expectancy, but "it's a relatively new situation for us, so evolutionary processes haven't had time to provide a way to deal with it," says Rohner, assistant investigator at Stowers. "But cavefish have been in these parasite-free caves for 150,000 years," which is a much longer time for evolution to come into play, and why the research team decided to take a closer look at cavefish.

In this study, published online July 20, 2020, in Nature Ecology & Evolution, Stowers researchers evaluated the environments of the Pachón cavefish and the closely-related Río Choy river (or surface) fish in Mexico. The fish look vastly different. For example, cavefish have much more fatty tissue, which helps them survive in a nutrient-scarce environment with infrequent feeding opportunities. But they are very close members of the same species, which make them suitable candidates for comparison. Also, surface fish live in parasite-rich environments, making them a natural type of control group for cavefish.

"We found an incredible number of parasites in surface fish - in the gut, skin, liver, gall bladder - everywhere. But we didn't find any parasites in the cavefish," says Peuss. "It's not too surprising because caves are a biodiversity-deprived environment. There are very few animals there, so there's less of a chance for parasites to find the hosts they need to survive."

Then, in the lab, the researchers looked at the innate and adaptive immune system of both types of fish. The innate immune system is the first line of defense against parasites and triggers an unspecific inflammatory response as a broad defense strategy, while the adaptive immune system is usually slower in mounting an immune response but this response is highly specifc. The first observation the team made was that, compared to surface fish, the cavefish innate immune system is much more sensitive when confronted with a potential threat, resulting in a stronger inflammatory response.

Interestingly, the team found that cavefish produce fewer cells that make up the innate immune system. This reduction in innate immune cells could potentially compensate for the increased sensitivity. But is the decreased number of innate immune cells in cavefish purely a consequence of fewer parasites in the cave, or are there other benefits from producing fewer of these cells that drive inflammation?

To answer this question, Rohner and his team looked at the body fat levels of the cavefish. Increased fatty tissue would normally increase inflammation as well - it's true in humans. But when the researchers examined the cavefish, that wasn't the case. Cavefish, which have much higher body fat levels than surface fish, did not show higher levels of inflammation.

"The reduction of innate immune cells in cavefish compared to surface fish is probably the cause for the lack of the inflammatory response," Peuss says. "This is particularly interesting since we know that in humans, higher levels of fatty tissue often mean a higher degree of inflammation, which can lead to secondary diseases such as type 2 diabetes."

Peuss points out that these findings bring about further questions to explore. For instance, they don't know the genetic factors that lead to the reduced production of innate immune cells in cavefish. The next step in this research is to try to identify those factors, and see if there might be similar factors in humans.

"It's really interesting that there are parallels with human health in terms of being hypersensitive in an environment where there are hardly any parasites, but that's already been shown in other vertebrates in labs since labs are parasite-free by design," Peuss says. "With the cavefish, we have an example to study how it developed in an environmental setting, and to look for a genetic basis of these traits."

Other coauthors include Andrew C. Box, Shiyuan Chen, Yongfu Wang, PhD, Dai Tsuchiya, Jenna L. Persons, PhD, Alexander Kenzior, Jaya Krishnan, PhD, and Brian D. Slaughter, PhD, from the Stowers Institute; Ernesto Maldonado, PhD, from Universidad Nacional Autonoma de Mexico, Puerto Morelos, Quintana Roo; and Jörn P. Scharsack from the University of Münster, Germany.

This work was funded by the Stowers Institute for Medical Research, grants from the Edward Mallinckrodt Jr. Foundation and JDRF (to NR), and a grant from the Deutsche Forschungsgemeinschaft (award PE 2807/1-1 to RP).

Lay Summary of Findings

Similar to people, cavefish live in an environment with a reduced number of parasites. Unlike people, however, cavefish have had much more time - about 150,000 years - to adapt to these conditions. To learn more about how a low-parasite environment may shape the evolution of a host's immune system, researchers from the laboratory of Nicolas Rohner, PhD, at the Stowers Institute for Medical Research examined the impact of decreased parasite abundance and infection on the evolution of the cavefish immune system.

In the study, the Stowers scientists and their collaborators characterized the cavefish immune system and how it responds to threats, compared to that of closely-related river fish from a parasite-rich environment. Their findings, published online July 20, 2020, in Nature Ecology & Evolution, show that cavefish differ in their sensitivity toward immune stimulants and have a different composition of immune cells, including a reduction of the immune cells that play a role in inflammation. In future studies, the scientists hope to identify genetic factors involved in cavefish immune system evolution. This research could provide clues about the development of immune system disorders and potentially human autoimmune diseases, where the immune system attacks its own body.

Seniors who can identify smells like roses, turpentine, paint-thinner and lemons, and have retained their senses of hearing, vision and touch, may have half the risk of developing dementia as their peers with marked sensory decline.

In a study by UC San Francisco, researchers tracked close to 1,800 participants in their seventies for a period of up to 10 years to see if their sensory functioning correlated with the development of dementia. At the time of enrollment, all participants were dementia-free, but 328 participants (18 percent) developed the condition over the course of the study.

Among those whose sensory levels ranked in the middle range, 141 of the 328 (19 percent) developed dementia. This compares with 83 in the good range (12 percent) and 104 (27 percent) in the poor range, according to the study, which publishes in Alzheimer's and Dementia: The Journal of the Alzheimer's Association on July 20, 2020.

Previous research has centered on the link between dementia and individual senses, but the UCSF researchers' focus was on the additive effects of multiple impairments in sensory function, which emerging evidence shows are a stronger indicator of declining cognition.

"Sensory impairments could be due to underlying neurodegeneration or the same disease processes as those affecting cognition, such as stroke," said first author Willa Brenowitz, PhD, of the UCSF Department of Psychiatry and Behavioral Sciences, and the Weill Institute for Neurosciences. "Alternatively, sensory impairments, particularly hearing and vision, may accelerate cognitive decline, either directly impacting cognition or indirectly by increasing social isolation, poor mobility and adverse mental health."

While multiple impairments were key to the researchers work, the authors acknowledged that a keen sense of smell, or olfaction, has a stronger association against dementia than touch, hearing or vision. Participants whose smell declined by 10 percent had a 19 percent higher chance of dementia, versus a 1-to-3-percent increased risk for corresponding declines in vision, hearing and touch.

"The olfactory bulb, which is critical for smell, is affected fairly early on in the course of the disease," said Brenowitz. "It's thought that smell may be a preclinical indicator of dementia, while hearing and vision may have more of a role in promoting dementia."

The 1,794 participants were recruited from a random sample of Medicare-eligible adults in the Health, Aging and Body Composition study. Cognitive testing was done at the beginning of the study and repeated every other year. Dementia was defined by testing that showed a significant drop from baseline scores, documented use of a dementia medication or hospitalization for dementia as a primary or secondary diagnosis.

Multisensory testing was done in the third-to-fifth year and included hearing (hearing aids were not allowed), contrast-sensitivity tests for vision (glasses were permitted), touch testing in which vibrations were measured in the big toe, and smell, involving identifying distinctive odors like paint-thinner, roses, lemons, onions and turpentine.

The researchers found that participants who remained dementia-free generally had higher cognition at enrollment and tended to have no sensory impairments. Those in the middle range tended to have multiple mild impairments or a single moderate-to-severe impairment. Participants at higher risk had multiple moderate-to-severe impairments.

"We found that with deteriorating multisensory functioning, the risk of cognitive decline increased in a dose-response manner," said senior author Kristine Yaffe, MD, of the UCSF departments of Psychiatry and Behavioral Sciences, Epidemiology and Biostatistics, and Neurology, as well as the San Francisco VA Health Care System. "Even mild or moderate sensory impairments across multiple domains were associated with an increased risk of dementia, indicating that people with poor multisensory function are a high-risk population that could be targeted prior to dementia onset for intervention."

The 780 participants with good multisensory function were more likely to be healthier than the 499 participants with poor multisensory function, suggesting that some lifestyle habits may play a role in reducing risks for dementia. The former group was more likely to have completed high school (85 percent versus 72.1 percent), had less diabetes (16.9 percent versus 27.9 percent) and were marginally less likely to have cardiovascular disease, high-blood pressure and stroke.

FRANKFURT/JENA. An interdisciplinary team from Frankfurt and Jena has developed a kind of bait with which to fish protein complexes out of mixtures. Thanks to this "bait", the desired protein is available much faster for further examination in the electron microscope. The research team has christened this innovative layer of ultrathin molecular carbon the "smart nanosheet". With the help of this new development, diseases and their treatment with drugs can be better understood, for example.

"With our process, new types of proteins can be isolated from mixtures and characterized within a week," explains Daniel Rhinow from the Max Planck Institute of Biophysics in Frankfurt. "To date, just the isolation of the proteins was often part of a doctorate lasting several years." Together with Andreas Terfort (Goethe University) and Andrey Turchanin (Friedrich Schiller University Jena), the idea evolved a few years ago of fishing the desired proteins directly out of mixtures by equipping a nanosheet with recognition sites onto which the target protein bonds. The researchers have now succeeded in making proteins directly available for examination using electron cryo-microscopy through a "smart nanosheet".

Electron cryo-microscopy is based on the shock-freezing of a sample at temperatures under -150 °C. In this process, the protein maintains its structure, no interfering fixing and coloring agents are needed, and the electrons can easily irradiate the frozen object. The result is high-resolution, three-dimensional images of the tiniest structures - for example of viruses and DNA, almost down to the scale of a hydrogen atom.

In preparation, the proteins are shock-frozen in an extremely thin layer of water on a minute metal grid. Previously, samples had to be cleaned in a complex procedure - often involving an extensive loss of material - prior to their examination in an electron microscope. The electron microscopy procedure is only successful if just one type of protein is bound in the water layer.

The research group led by Turchanin is now using nanosheets that are merely one nanometer thick and composed of a cross-linked molecular self-assembled monolayer. Terfort's group coats this nanosheet with a gelling agent as the basis for the thin film of water needed for freezing. The researchers then attach recognition sites (a special nitrilotriacetic acid group with nickel ions) to it. The team led by Rhinow uses the "smart nanosheets" treated in this way to fish proteins out of a mixture. These were marked beforehand with a histidine chain with which they bond to the recognition sites; all other interfering particles can be rinsed off. The nanosheet with the bound protein can then be examined directly with the electron microscope.

"Our smart nanosheets are particularly efficient because the hydrogel layer stabilizes the thin film of water required and at the same time suppresses the non-specific binding of interfering particles," explains Julian Scherr of Goethe University. "In this way, molecular structural biology can now examine protein structures and functions much faster." The knowledge gained from this can be used, for example, to better understand diseases and their treatment with drugs.

The team has patented the new nanosheets and additionally already found a manufacturer who will bring this useful tool onto the market.

ST. LOUIS, MO, July 20, 2020 - Fungal diseases cause substantial losses of agricultural harvests each year. The fungus Botrytis cinerea causing gray mold disease is a major problem for farmers growing strawberries, grapes, raspberries, tomatoes and lettuce. To mitigate the problem, they often resort to applying chemical fungicides which can lose their effectiveness over time. Danforth Center scientists, Dilip Shah, PhD, research associate member, Siva Velivelli, PhD, postdoctoral associate, Kirk Czymmek, PhD, principal investigator and director, Advanced Bioimaging Laboratory and their collaborators at the Pacific Northwest National Laboratory have identified a sub class of peptides in the nodules of the legume, Medicago truncatula that proved effective in inhibiting growth of the fungus causing gray mold. The results of their research, Antifungal symbiotic peptide NCR044 exhibits unique structure and multifaceted mechanisms of action that confer plant protection, were recently published in the journal, Proceedings of the National Academy of Sciences.

"We are excited about the possibility of developing this class of peptides as a spray-on fungicide that would provide farmers with an environmentally friendly alternative to chemical fungicides for pre- and post-harvest management of fungal diseases," said Dilip Shah. "When applied to crops, the peptides will eventually break down to amino acids in the soil and be used by beneficial microbes as an energy source."

Medicago truncatula is a relative of alfalfa. Shah and his team produced recombinantly large quantities of the highly charged NCR044 peptide that is expressed in the nodules of this legume. They then applied the peptide in low concentrations to tobacco and tomato plants in the lab and challenged the plants with the gray mold fungus. The plants showed significant protection from this fungal disease.

To understand the antimicrobial mechanism within the cell, they collaborated with Czymmek, who is also a mycologist and has studied fungal cell biology for many years. Using time-lapse confocal and super resolution microscopy, the team was able to observe dynamically how the peptide binds to fungal spores and germlings, how it is internalized and where it goes inside the fungal cell. One key finding here was the confirmation that the peptide concentrated in the nucleolus, the organelle where ribosomal assembly takes place.

"It was a pleasure to work with Dilip and his team. As a young scientist, Siva, was able to move diligently across a very diverse set of platforms and techniques, following-up on leads from the scientific data. Ultimately, he was able to apply these corroborating techniques and uncover significant new information to create robust conclusions about the research project," said Czymmek, "It was really great science."

The unique team of scientists with expertise in fungal and plant cell biology combined with advanced imaging capabilities allowed them to make critical interpretations and confirm their hypotheses. Their collaborator and co-author on the paper, Garry Buchko, PhD at the Pacific Northwest National Laboratory solved the first three-dimensional structure of a nodule-specific peptide revealing a largely disordered, and highly dynamic, peptide structure containing a short anti-parallel β-sheet, tiny α-helix, and when oxidized, two stabilizing disulfide bonds.

A portion of the project was funded by TechAccel. Shah and Czymmek will continue their research and have applied to the National Science Foundation for a grant to further explore how antifungal nodule-specific peptides kill harmful fungal pathogens in vitro and in planta.

Images are available upon request.

In a famous parable, three blind men encounter an elephant for the first time. Each touches a part--the trunk, ear, or side--and concludes the creature is a thick snake, fan, or wall. This elephant, said Kang-Kuen Ni, is like the quantum world. Scientists can only explore a cell of this vast, unknown creature at a time. Now, Ni has revealed a few more to explore.

It all started last December, when she and her team completed a new apparatus that could achieve the lowest temperature chemical reactions of any currently available technology and then broke and formed the coldest bonds in the history of molecular coupling. But their ultracold reactions also unexpectedly slowed the reaction to a sluggish speed, gifting the researchers with a real-time glimpse of what happens during a chemical transformation. Now, though reactions are considered too fast to measure, Ni not only determined the lifetime of that reaction, she solved an ultracold mystery in the process.

With ultracold chemistry, Ni, the Morris Kahn associate professor of chemistry and chemical biology and of physics, and her team cooled two potassium-rubidium molecules to just above absolute zero and found the "intermediate," the space where reactants transform into products, lived for about 360 nanoseconds (still billionths of a second, but long enough). "It's not the reactant. It's not the product. It's something in-between," Ni said. Watching that transformation, like touching the side of an elephant, can tell her something new about how molecules, the foundation of everything, work.

But they didn't just watch.

"This thing lives so long that now we can actually mess around with it... with light," said Yu Liu, a graduate student in the Graduate School of Arts and Sciences and first author on their study published in Nature Physics. "Typical complexes, like those in a room-temperature reaction, you wouldn't be able to do much with because they dissociate into products so quickly."

Like Star Trek tractor beams, lasers can trap and manipulate molecules. In ultracold physics, this is the go-to method to capture and control atoms, observe them in their quantum ground state or force them to react. But when scientists moved from manipulating atoms to messing with molecules, something strange happened: molecules started to disappear from view.

"They prepared these molecules, hoping to realize many of the applications that they promise--building quantum computers, for example--but instead what they see is loss," Liu said.

Alkali atoms, like the potassium and rubidium Ni and her team study, are easy to cool down in the ultracold realm. In 1997, scientists won a Nobel Prize in Physics for cooling and trapping alkali atoms in laser light. But molecules are wonkier than atoms: They aren't just a spherical thing sitting there, said Liu, they can rotate and vibrate. When trapped together in the laser light, the gas molecules bumped against each other as expected, but some simply disappeared.

Scientists speculated that the molecular loss resulted from reactions--two molecules bumped together and, instead of heading off in different directions, they transformed into new species. But how?

"What we found in this paper answers that question," Liu said. "The very thing that you use to confine the molecule is killing the molecule." In other words, it's the light's fault.

When Liu and Ni used lasers to manipulate that intermediate complex--the middle of their chemical reaction--they discovered the light forced the molecules off their typical reaction path and into a new one. A pair of molecules, stuck together as an intermediate complex, can get "photo-excited" instead of following their traditional path, Liu said. Alkali molecules are particularly susceptible because of how long they live in their intermediate complex.

"Basically, if you want to eliminate loss," Liu said, "you've got to turn off the light. You've got to find another way to trap these things." Magnets, for example, or electric fields can trap molecules, too. "But these are all technically demanding," said Liu. Light is just simpler.

Next, Ni wants to see where these complexes go when they disappear. Certain wavelengths of light (like the infrared the team used to excite their potassium-rubidium molecules) can create different reaction paths--but no one knows which wavelengths send molecules into which new formations.

They also plan to explore what the complex looks like at various stages of transformation. "To probe its structure," Liu said, "we can vary the frequency of the light and see how the degree of excitation varies. From there, we can figure out where the energy levels of this thing are, which informs on its quantum mechanical construct."

"We hope this will serve as a model system," Ni said, an example for how researchers can explore other low temperature reactions that don't involve potassium and rubidium.

"This reaction is, like many other chemical reactions, sort of a universe in its own," said Liu. With each new observation, the team reveals a tiny piece of the giant quantum elephant. Since there are an infinite number of chemical reactions in the known universe, there's still a long, long way to go.