Brain

With brilliant colors and picturesque shapes, many crystals are wonders of nature. Some crystals are also wonders of science, with transformative applications in electronics and optics. Understanding how best to grow such crystals is key to further advances.

Scientists from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, along with three universities, have revealed new insights into the mechanism behind how gallium nitride crystals grow at the atomic scale.

Gallium nitride crystals are already in wide use in light-emitting diodes, better known as LEDs. They might also be applied to form transistors for high-power switching electronics to make electric grids more energy efficient and smarter. The use of such “smart grids,” which could better balance high power within the overall system, might prevent people from losing power in severe storms.

“This work is a great example of the importance and power of probing a material while a process is underway. Quite often when we use such probes to study processes like synthesis, we find the story to be more complex than we originally thought and counter to conventional wisdom.” — Matt Highland, X-ray Sciences division, Argonne National Laboratory

The same technology could also make individual homes more energy efficient. And it could find use in optical communications, where lasers transmit information. Such information transfer can be more precise, faster and more secure than current capabilities.

Because of these diverse applications, scientists worldwide have been working to improve the process for growing gallium nitride crystals.

“Gallium nitride has a more complicated crystal structure than silicon, the typical crystalline material in electronics,” said G. Brian Stephenson, an Argonne distinguished fellow in the Materials Science division. “When you grow this crystal, you thus get more fascinating behavior at the surface.”

At the atomic scale, a growing gallium nitride crystal surface typically looks like a staircase of steps, where every stair is a layer of the crystal structure. Atoms are added to a growing crystal surface by attachment at the edges of the steps. Because of the gallium nitride crystal structure, the steps have alternating edge structures, labeled A and B. The different atomic structures lead to different growth behaviors of the A and B steps. Most theoretical models indicate that atoms accumulate faster on a B-type step, but experimental confirmation has been lacking.

“Because of the high temperatures and chemical atmosphere involved, it is not possible to examine the growth of gallium nitride with a standard electron microscope and test the model prediction,” Stephenson said. For that, the team called upon the Advanced Photon Source (APS), a DOE Office of Science User Facility at Argonne.

The very high energy of the X-rays available at the APS with a beam only a few micrometers wide (beamline 12-ID-D) allowed the team to monitor the rate of gallium nitride growth on the crystal surface steps. These X-rays are an ideal probe since they are sensitive to atomic-scale structure and can penetrate the environment of the crystal at the high temperatures involved, over 1400 degrees Fahrenheit, while it is growing.

“Based on modeling, many had assumed that atoms probably build up faster on the type-B step,” Stephenson said. “Imagine our surprise when it turned out to be step A. This suggests the chemistry of the growth process may be more complicated than previously thought.”

“This work is a great example of the importance and power of probing a material while a process is underway,” added Matt Highland, physicist in the X-ray Sciences division. “Quite often when we use such probes to study processes like synthesis, we find the story to be more complex than we originally thought and counter to conventional wisdom.”

The results have obvious implications for refining the current understanding of the atomic-scale mechanisms of gallium nitride growth. This understanding has important practical implications for design of advanced gallium nitride devices by allowing better control of growth and incorporation of additional elements for improved performance. The findings can also be applied to growth of related crystals, including host semiconductor materials for quantum information science.

This research was supported by the DOE Office of Basic Energy Sciences. It was reported in Nature Communications, in a paper titled “In situ microbeam surface X-ray scattering reveals alternating step kinetics during crystal growth.” In addition to Stephenson and Highland, other Argonne authors include Guangxu Ju, Dongwei Xu (now at Huazhong University of Science and Technology), Eastman and Peter Zapol. University participants include Carol Thompson (Northern Illinois University) and Weronika Walkosz (Lake Forest College).

The multifunctional porous solids with diverse functionalized linkers have been utilized as promising materials for various applications in energy, environmental and biomedical areas. Although their emerging properties are ascribed to varying pore types resulting from combinations of functional groups, the chemical environment of the pores remains an open question. A new synthetic platform where the population of pores can be identified and further controlled is of great interest in materials science.

A research team, led by Professor Wonyoung Choe and Professor Tae-Hyuk Kwon in Department of Chemistry at Ulsan National Institute of Science and Technology (UNIST), South Korea, has recently unveiled a new synthetic approach for controlling functional group assemblies in porous solids by using a cage-based framework, also known as metal-organic polyhedra (MOPs). Their findings are expected to have attracted attention as a useful synthetic strategy for catalysis, gas storage, and molecular separation.

MOPs are the three-dimensional assembly of discrete cages. While MOPs share compositional similarities (i.e., metal clusters and organic linkers) with their solid-state counterparts, metal-organic frameworks (MOFs), the discrete and soluble nature of MOPs provides a unique advantage. In their study, the research team developed two-step self-assembly where functionalized cages are mixed. The authors call the new synthetic strategy as 'mixed-cage', which is drastically different from the conventional mixing strategy, so-called 'mixed-linker'. While mixed-linker strategy results in a random distribution of functionalized organic linkers over the framework, mixed-cage strategy yields identical functional groups on each cage unit.

Moreover, the research team demonstrated distinct solvatochromic behavior between two multifunctional solids produced by mixed-linker and mixed-cage strategies. They investigated the color changes of fluorescence emissions depending on the solvent polarity. While mixed-linker sample showed pronounced color changes, mixed-cage sample was only slightly affected by the solvent types. The authors further uncovered the detailed photophysical properties using films. Attributed to radiative decay kinetics of mixed-cage sample, greater than that of mixed-linker sample, higher emission intensity was observed for mixed-cage sample.

"Structure determines function and solids are not the exceptions," said Professor Wonyoung Choe. "Yet, what is more interesting here is that we find a new way to control the assembly of packing, using metal-organic polyhedra." He adds, "Such advance can alter the way of controlling the molecule-based solids."

What explains how often people travel to a particular place? Your intuition might suggest that distance is a key factor, but empirical evidence can help urban studies researchers answer the question more definitively.

A new paper by an MIT team, drawing on global data, finds that people visit places more frequently when they have to travel shorter distances to get there.

"What we have found is that there is a very clear inverse relationship between how far you go and how frequently you go there," says Paolo Santi, a research scientist at the Senseable City Lab at MIT and a co-author of the new paper. "You only seldom go to faraway places, and usually you tend to visit places close to you more often. It tells us how we organize our lives."

By examining cellphone data on four continents, the researchers were able to arrive at a distinctive new finding in the urban studies literature.

"We might shop every day at a bakery a few hundred meters away, but we'll only go once a month to the fancy boutique miles away from our neighborhood. This kind of intuitive notion had never been empirically tested. When we did it we found an incredibly regular and robust law -- which we have called the visitation law," says Carlo Ratti, a co-author of the paper and director of the Senseable City Lab, which led the research project.

The paper, "The universal visitation law of human mobility," is published today in Nature.

The paper is co-authored by Markus Schläpfer, a scholar in the Urban Complexity Project at the ETH Future Cities Lab in Singapore; Lei Dong, a researcher at Peking University in Beijing; Kevin O'Keeffe, a postdoc at the MIT Senseable City Lab; Santi, a research director at Istituto di Informatica e Telematica, CNR (the National Research Council of Italy); Michael Szell, an associate professor in Data Science at IT University of Copenhagen; Hadrien Salat of the Future Cities Laboratory, Singapore-ETH Centre; Samuel Anklesaria, a researcher at the MIT Senseable City Lab; Mohammad Vazifeh, a senior postdoc at the MIT Senseable City Lab; Ratti; and Geoffrey West, a professor at and former president of the Santa Fe Institute. Schläpfer, Dong, Santi, and Szell are also former members of the Senseable City Lab.

To conduct the study, the researchers used anonymized cellphone data from large communications providers to track the movement of people in the metro areas of Abidjan, Ivory Coast; Boston; Braga, Lisbon, and Porto, Portugal; Dakar, Senegal; and Singapore.

Cellphone data are ideal for this kind of study because they establish both the residence area of people and the destinations they travel to. In some cases, the researchers defined areas visited by using grid spaces as small as 500 square meters. Overall, the researchers charted over 8 billion location-indicating pieces of data generated by over 4 million people, charting movement for a period of months in each location.

And, in each case, from city to city, the same "inverse law" of visitation held up, with the charted data following a similar pattern: The frequency of visits declined over longer distances, and higher-density areas were filled with people who had, on aggregate, taken shorter trips. To the extent that there was some variation from this pattern, the largest deviations involved sites with atypical functions, such as ports and theme parks.

The paper itself both measures the data and presents a model of movement, in which people seek out the closest locations that offer particular kinds of activity. Both of those buttress "central place theory," an idea developed in the 1930s by German scholar Walter Christaller, which seeks to describe the location of cities and towns in terms of the functions they offer to people in a region.

The scholars note that the similarity in movement observed in very different urban areas helps reinforce the overall finding.

"This generalized behavior is not just something you observe in Boston," Santi says. "From a scientific viewpoint, we are adding evidence about a generalized pattern of behavior."

The researchers also hope the finding, and the methods behind it, can be usefully applied to urban planning. Santi suggests this type of study can help predict how substantial changes in the physical layout of a city will affect movement within it. The method also makes it possible to examine how changes in urban geography affect human movement over time.

"The visitation law could have many practical applications -- from the design of new infrastructure to urban planning," adds Ratti. "For instance, it could help implement the concept of the 'Fifteen-Minute City,' which aims to reorganize physical space around walkable neighborhoods and which has become very popular during the Covid-19 pandemic. Our law suggests that we can indeed capture a large fraction of all urban trips within a fifteen-minute radius, while leaving the rest -- perhaps 10 percent -- further away."

Children of Latinx immigrants who take on adult responsibilities exhibit higher levels of political activity compared with those who do not, according to University of Georgia researcher Roberto Carlos.

Immigrant communities often display low levels of political engagement, but a new study by Carlos indicates that when children of Latinx immigrants take on adult roles because of parents' long work hours, immigrant status or language deficiencies, they develop noncognitive skills associated with higher rates of political participation.

"There is thriving in spaces that we wouldn't necessarily expect because of the hardship related to these environments," said Carlos, assistant professor of political science in the School of Public and International Affairs. "Instead of dismissing groups as inactive or disengaged, we just need to figure out where to look--sometimes in places we haven't typically examined--to see how they participate in the political process."

Previous research has described the noncognitive skills developed during adolescence that are positively associated with voter turnout. Some of these skills include general self-efficacy, even-temperedness, hard work, patience, altruism and follow-through.

Language brokering affects behavior

In the paper, published in American Political Science Review, Carlos posits that taking on adult responsibilities--language brokering, specifically--helps the children of Latinx immigrants develop the noncognitive skills associated with higher rates of political participation. Language brokering, when children translate or interpret for parents or other family members, runs the gamut from everyday interactions like a trip to the grocery store to high-stakes situations like hospital visits or interactions concerning immigration status.

"Young people are providing these services roughly from the time they're 6 or 7, and my argument is that if they can prevail in these spaces, they're going to be able to overcome the obstacles typically associated with political participation," he said. "And it's clear that they do."

Carlos combined three studies -- a survey of Latinx college students, a survey of young adults known as GenForward, and a 10-year longitudinal study -- to examine how mundane household experiences translate to political engagement.

The survey of Latinx college students indicated that respondents on the high end of the language brokering scale are substantially more likely to report political activity: 19% more likely to rally, 12% more likely to attend political meetings, and 20% more likely to sign petitions, compared with the average college student in the sample who does not serve as a language broker.

The GenForward survey, taken just after the 2016 presidential election, examined the effect of language brokering in the Latinx community and other ethnic groups including Asian and Black respondents. In the survey, 33% reported that both parents are immigrants, and of those 33%, more than half (59%) reported having served as a language broker for their parents. The results revealed that responders who acted as language brokers were 11% more likely to talk politics with their parents, 12% more likely to suggest a political party or candidate to their parents, and 7% more likely to start political conversations at home with their parents, compared to nonbrokers.

The impact of household chores

The Educational Longitudinal Study, conducted with high school sophomores starting in 2002 through 2012, examined the frequency of household responsibilities. Results revealed that children who were assigned household chores were 5%-6% more likely to vote in the 2004 and 2008 presidential elections and 8% more likely to vote in local and midterm elections than children who did not take on any chores.

Previous research on the effect of household chore assignment suggests that it is likely weighted along racial and social class lines because children of color and children in low socioeconomic environments are more likely to have to step up to help parents. Results of the ELS indicated that nonwhite students frequently assigned household chores were
8% more likely to vote in the 2004 presidential election and 9% more likely to vote in off-year elections, compared with other nonwhite students who did not take on any chores.

The largest differences were revealed in household chore assignments' effect by class. Household chore assignment had no influence on those who had at least one parent with a college degree. But for those whose parents had not earned a college degree, taking on household chores meant they were 6%-8% more likely to vote in local or midterm elections as well as the 2004 and 2008 presidential elections, compared with those who did not take on any chores.

"The frequency of chore assignments actually has a pretty big impact on turnout compared to traditional influences we think about, like parents' education or a young person's own educational status, income, even access to newspapers as a kid," Carlos said. "Sometimes those effects wash away, but this chore assignment variable is persistent even in midterm elections that typically have low-level turnout."

These findings provide new insights into how the cycle of generational political inequality is overcome in unexpected ways and places. If these kids can be relied on at a young age to contribute, we shouldn't be surprised that they contribute to society through these participatory avenues when they're adults, Carlos said.

The prevalent views on political socialization and the ways people participate took a foothold in the 1960s, when immigration flows were at their lowest levels and immigrant communities weren't really being examined, according to Carlos. That led to a mainstream narrative that tends to be largely white and heteronormative--it's not wrong, but it's incomplete, he said.

"My question was: What about immigrant communities? There's no top-down political socialization, necessarily. Values are, of course, being transmitted from immigrant parents to their children, but there's not always a clear indication that those values neatly map on to the American two-party system, especially if you're a new immigrant," he said.

"This paper highlights that we should consider looking at other political behaviors beyond voting. People who do this type of language brokering may be unable to vote, but that doesn't mean that they're not involved in the political process."

The goal of Kaare Hartvig Jensen, Associate Professor at DTU Physics, was to reduce the need for harvesting, transporting, and processing crops for the production of biofuels, pharmaceuticals, and other products. The new method of extracting the necessary substances, which are called plant metabolites, also eliminates the need for chemical and mechanical processes.

Plant metabolites consist of a wide range of extremely important chemicals. Many, such as the malaria drug artemisinin, have remarkable therapeutic properties, while others, like natural rubber or biofuel from tree sap, have mechanical properties.

Harvesting cell by cell

Because most plant metabolites are isolated in individual cells, the method of extracting the metabolites is also important, since the procedure affects both product purity and yield.

Usually the extraction involves grinding, centrifugation, and chemical treatment using solvents. This results in considerable pollution, which contributes to the high financial and environmental processing costs.

"All the substances are produced and stored inside individual cells in the plant. That's where you have to go in if you want the pure material. When you harvest the whole plant or separate the fruit from the branches, you also harvest a whole lot of tissue that doesn't contain the substance you're interested in," explains Kaare Hartvig Jensen.

"So there are two perspectives to it. If you want to extract the pure substances, you need to do it cell by cell. And when you can do that, as we've shown, you don't have to harvest the plant. Then you can put the little robot on and it can work without damaging the plant," says Kaare.

The team is currently working with plants and leaves, but in the future this type of harvester may be used on a slightly larger scale.

The hope is that this unique approach can create a new source of biomass and spark research into a new area of sustainable energy production.

One thing the technology might be used for in the future is tapping energy from trees, which contain a lot of biofuel.

"In the forests of northern Canada and Russia, there are spruce forests with around 740 billion trees that are completely untouched. That's about 25% of the total number of trees on the planet. By developing this technology, we can tap trees for sugar and make biofuel without chopping down or damaging the trees," explains Kaare.

Artificial intelligence at a microscopic level

The cells in the fruit and leaves that the harvester looks for are 100 microns in diameter, and the tip of the needle is around 10 microns in diameter. The harvest is therefore happening on the scale of the width of a hair.

Magnus Valdemar Paludan, the PhD student at DTU Physics who created the system of image analysis, image recognition, and robot control, explains.

"It's all done with a microscope camera. To begin with, I manually marked pixels on the microscopy images showing the cells that the robot will harvest. That information can be used to train a computer to find similar cells in new images."

Machine learning and a pre-existing neural network, GoogLeNet, are the building blocks of the technology. The network can already recognize macroscopic structures and can sift through an image and tell you if, for example, there's an elephant or a red pepper hiding in the photo.

"We used a technique called transfer learning, where you use the existing neural network's ability to recognize different objects in an image. By showing the computer a number of new images with the manually marked cells, we succeeded in adjusting the network's parameters so it recognizes the microscopic metabolite-rich cells," says Magnus.

"The harvester can then go in and take a picture of the leaf with the microscope camera, run it through the software, and recognize the cells it needs to harvest. Next, it can extract the chemicals automatically using a microrobot, while the rest of the plant remains undisturbed," explains Magnus.

A novel compound similar in structure to the psychedelic drug ibogaine, but lacking its toxic and hallucinogenic effects, has been found to rapidly reverse the effects of stress in mice.

Researchers found that a single dose of tabernanthalog (TBG) can correct stress-induced behavioral deficits, including anxiety and cognitive inflexibility, and also promotes the regrowth of neuronal connections and restores neural circuits in the brain that are disrupted by stress. The study was published May 25 in Molecular Psychiatry.

"It was very surprising that a single treatment with a low dose had such dramatic effects within a day," said corresponding author Yi Zuo, professor of molecular, cell, and developmental biology at UC Santa Cruz. "I had a hard time believing it even when I saw the initial data."

TBG was developed in the lab of coauthor David Olson at UC Davis. Zuo's lab worked with Olson on the initial studies of TBG, reported in Nature in 2020. The new study focused on the deleterious effects of stress using a protocol in which mice are subjected to mild, unpredictable stressors over a period of several days.

On the behavioral level, stress causes increased anxiety, deficits in sensory processing, and reduced flexibility in decision-making. In the brain, stress disrupts the connections between neurons and alters the neuronal circuitry, resulting in an imbalance between excitation and inhibition.

"Amazingly, TBG reversed all of the effects of stress," Zuo said. "This study provides significant insights into neural mechanisms underlying the therapeutic effects of psychedelic analogs on mental illnesses and paves the way for future investigations to understand their cellular and circuit mechanisms."

In recent years, there has been renewed interest in the use of psychedelic substances for treating illnesses such as addiction, depression, anxiety, and posttraumatic stress disorder. The hallucinogenic effects of these drugs remain a concern, however, and scientists have been unsure whether the hallucinations are therapeutically important or just a side effect.

Ibogaine has shown promise for treating addiction, but it causes dangerous heart arrhythmias in addition to being a powerful hallucinogen. TBG has not yet been tested in humans, but it lacks ibogaine's toxicity in animal tests, and it doesn't induce the head-twitch behavior in mice caused by known hallucinogens.

Initial studies of TBG found that it had antidepressant effects and reduced addictive behaviors in rodents. The new study was initiated by co-first author Michelle Tjia, then a graduate student in Zuo's lab studying the effects of stress. After Tjia left for a postdoctoral position, co-first author Ju Lu, a project scientist in the lab, led additional studies. The researchers conducted a range of tests to evaluate behavioral responses to stress and the effects of treatment with TBG. They also performed imaging studies to assess changes in the brains of the mice at the neuronal level.

Studies using animal models--conducted in accordance with NIH regulations and reviewed and approved by Institutional Animal Care and Use Committees--remain vital to investigating complex psychiatric disorders.

Reno, Nev. (May 25, 2021) - After a wildfire, soils in burned areas often become water repellent, leading to increased erosion and flooding after rainfall events - a phenomenon that many scientists have attributed to smoke and heat-induced changes in soil chemistry. But this post-fire water repellency may also be caused by wildfire smoke in the absence of heat, according to a new paper from the Desert Research Institute (DRI) in Nevada.

In this pilot study (exploratory research that takes place before a larger-scale study), an interdisciplinary team of scientists led by DRI Associate Research Professor of Atmospheric Science Vera Samburova, Ph.D., exposed samples of clean sand to smoke from burning Jeffrey pine needles and branches in DRI's combustion chamber, then analyzed the time it took for water droplets placed on the sand surface to be absorbed - a measure of water repellency.

The pilot study investigated the effects of smoke and heat on water repellency of the sand, and was the first study to also incorporate an analysis of cold smoke. In the experiments, sand was used in place of soil because it could be cleaned thoroughly and analyzed accurately, and Jeffrey pine for a fuel source because it represents a common wildland fire fuel in the Western U.S.

Before exposure to Jeffrey pine smoke, water droplets placed on the surface of the sand samples were quickly absorbed. But after exposure to smoke, the sand samples showed severe-to-extreme water repellency, in some cases retaining water droplets on the soil surface for more than 50 minutes without soaking in. It made little difference whether or not samples had been exposed to heat and smoke, or just cold smoke.

"The classic explanation for fire-induced water repellency is that it is caused as smoke diffuses under rather hot conditions and settles down into the soils, but our work shows that the smoke does not have to be hot to turn the sand hydrophobic -- simply the presence of the chemical substances in the smoke is enough," Samburova said. "This is something we really need to look deeper into, because soil water repellency leads to increases in flooding, erosion, and surface runoff."

This study built on previously published work by former DRI postdoctoral researcher Rose Shillito, Ph.D., (currently with the U.S. Army Corps of Engineers), Markus Berli, Ph.D., of DRI, and Teamrat Ghezzehei, Ph.D., of University of California, Merced, in which the researchers developed an analytical model for relating soil water repellency to infiltration of water.

"Our earlier paper focused on how fire changes the properties of soils, from a hydrology perspective," Berli said. "In our current study, we were interested in learning more about the chemistry behind the process of how soils come to be hydrophobic. We're bringing together geochemistry and organic geochemistry with soil physics and hydrology to understand the impact of fire-induced water repellency on hydrology."

The project team is now working on a larger proposal to further investigate questions touched on by this study about the roles of heat and smoke in fire-induced water repellency. Among other things, they would like to know how long soil water repellency lasts after a fire, and gain a better understanding of the detailed processes and mechanisms through which cold smoke affects the soil.

Gaining a thorough understanding of the process that leads to fire-induced soil water repellency is important," because and managers need this information in order to accurately predict where soils are likely to be hydrophobic after a fire, Berli explained.

"We still don't really understand the processes that lead to this fire-induced soil water repellency," Berli said. "Depending on what we find, the measures to predict fire-induced water repellency might be different, and this can have a significant impact on how we can predict and prevent flooding or debris flows that happen after a fire."

"This study was one big step forward, but it highlights the importance of future research on how fires affect soil, because wildfires are affecting thousands and thousands of square kilometers of land each year in the Western U.S.," Samburova added. "Some of our future goals are to find out how exactly this soil water repellency happens, where it happens, and how long it lasts."

A new study finds that fly ash--particles left over from burning coal--make up between 37 and 72 percent of all particulate organic carbon carried by the Yangtze River in China, or around 200,000 to 400,000 tons of carbon per year.

The study, which is the first of its kind, shows just how big an impact fossil fuel consumption has on Earth. Beyond pumping carbon dioxide into the atmosphere, coal burning dumps about as much particulate carbon into the Yangtze River as natural processes do.

The findings were published in the Proceedings of the National Academy of Sciences (PNAS) on May 17.

"About one-fifth of the world's coal consumption occurs along this river," says Gen Li, postdoctoral scholar research associate at Caltech and lead author of the PNAS paper. "We knew that would have an impact on the river; we just had no idea how big an impact it would be."

The Yangtze River is the third largest river in the world, cutting east across central China from the Tibetan plateau to the sea at Shanghai. China is the world's largest consumer of coal today, burning 2,500 megatons of coal in 2008, when the samples for this study were collected, and over 4,000 megatons of coal in 2020. (Although the total amount of coal burned in China increased from 2008 to 2020, the country also improved its regulation, recollection, and storage of fly ash over that period; now, approximately 80 percent is immediately retrieved.)

Coal fly ash is the unreactive particulate byproduct of burning coal--the fine grains that do not burn but rather become sooty smoke. Those particles, composed of minerals and fossilized particulate organic carbon on the same scale as silt or clay particles, are dangerous when inhaled but are also heavy and settle out of the air.

Most of it is captured for use in industry as an additive to cements and concretes, in which it improves workability as well as overall strength. It is also used in agriculture as a fertilizer. However, a portion of it escapes capture, ultimately collecting in rivers and washing downstream with the normal sediment that erodes out of riverbeds.

"This is a new angle for carbon emissions that we haven't tracked before," says Woodward Fischer, professor of geobiology and co-author of the PNAS paper. "The fact that human processes are producing about as much as natural processes in this region shows just how much of a problem this is."

Next, the team plans to continue to examine the role of coal fly ash in other large river basins near dense populations--for example, the Mississippi River. Meanwhile, the researchers will study sediment cores taken offshore from the Yangtze River outflow to see if they can identify coal fly ash there.

"We're just beginning to appreciate how rivers are massive conduits for carbon at the earth surface," Fischer says. "By studying them further, we can quantify, evaluate, and, with future planning, potentially mitigate inimical human impacts on the carbon cycle."

Using intermittent electric energy to convert excessive CO2 into C2 products, such as ethylene and ethanol, is an effective strategy to mitigate the greenhouse effect. Copper (Cu) is the only single metal catalyst which can converts CO2 into C2 products by electrochemical method, but with undesirable selectivity of C2 product. Therefore, how to improve the conversion efficiency of Cu-based catalysts for reducing CO2 to C2 product has attracted great attention.

Recently, a research team led by Prof. Min Liu from Central South University, China designed a Cu-Pd bimetallic electrocatalyst possessing CuPd(100) interface which can lower the energy barrier of C2 product generation. The electrocatalyst was obtained through using an in-situ growth method based on thermal reduction to afford Pd nanoparticles as nucleated seeds. The results were published in Chinese Journal of Catalysis.

Generally, there are two limiting factors for achieving the electroreduction of CO2 to C2 products, namely the amount of CO* intermediate (* indicates the intermediate is adsorbed on the surface of the catalyst) and the C-C coupling step (generally two CO* coupling). For Cu catalysts, the energy barrier of the C-C coupling step is relatively low. However, the CO2 adsorption and CO2* hydrogenation ability of Cu are unfavorable, resulting in insufficient amount of CO* involved in subsequent C-C coupling step. Palladium (Pd) is an efficient catalyst that exhibited strong CO2 adsorption and ultrafast reaction kinetics for CO* formation. However, CO* poisoning on the Pd surface makes it unsuitable for generating C2 products. To take full advantage of both Cu (low energy barrier of C-C coupling) and Pd (ultrafast kinetics for CO* formation), the assembly of a CuPd bimetallic catalyst was envisaged as a potential method for optimizing the efficiency of C2 product formation.

The density functional theory (DFT) calculation shows that the CuPd (100) interface enhanced the adsorption of CO2 and reduced the energy barrier of CO2* hydrogenation step, thus sufficient CO* participated in the C-C coupling reaction. In addition, the energy barrier of rate-determining step for C2 product generation on CuPd (100) interface is 0.61 eV, which is lower than that on Cu(100) surface (0.72 eV).

Then the target CuPd (100) interface catalyst was prepared by a simple wet chemical method and proved by different characterization methods. The temperature programmed desorption and gas sensor experiment results proved the enhanced CO2 adsorption and CO2* hydrogenation ability on CuPd(100) interface, respectively. As a result, the CuPd(100) interface catalyst exhibited a C2 Faradaic efficiency of 50.3%, which was 2.1 times higher than that of Cu catalyst (23.6%) at -1.4 VRHE in 0.1 M KHCO3. This work provides a reference for the rational design of Cu-based electrocatalyst for CO2 electroreduction by adjusting the intermediate reaction energy barrier.

Newly published papers further elucidate the mechanisms underlying pridopidine’s neuroprotective properties through activation of the Sigma-1 Receptor (S1R).

Pridopidine enhances mitochondrial function and reduces mHTT-induced ER stress, which are impaired in HD, mediated by the S1R.

Three new peer-reviewed publications highlight pridopidine’s therapeutic potential and provide data supporting the role of the S1R in neurodegenerative diseases

Prilenia Therapeutics B.V., a clinical stage biotech company focused on developing novel treatments for neurodegenerative and neurodevelopmental disorders, today announces the publication of three peer-reviewed journal articles, highlighting key aspects of the mechanism of action of its lead asset, pridopidine, and the importance of S1R activation as a mechanism to attenuate biological features of neurodegenerative diseases.

S1R is a protein highly expressed in the brain where it regulates several cellular mechanisms common to neurodegenerative diseases. Activation of the S1R improves energy production, reduces cellular stress, enhances clearance of toxic proteins and mitigates inflammation, thus supporting the continued function and survival of neurons.

These latest publications are the result of long-term collaborations with researchers from leading institutions across the globe and provide novel insights into the mechanisms driving pridopidine neuroprotective effects.

Highlights from the published articles include the following:

1. The Sigma-1 Receptor Mediates Pridopidine Rescue of Mitochondrial Function in Huntington Disease Models - Naia et al., Neurotherapeutics, 2021

* This article describes how pridopidine enhances mitochondrial functions by activation of the S1R, contributing to its neuroprotective effects and supporting its therapeutic potential in HD

2. Pridopidine reduces mutant huntingtin-induced endoplasmic reticulum stress by modulation of the Sigma-1 receptor - Shenkman et al., Journal of Neurochemistry, 2021

* This article demonstrates the effect of pridopidine on reducing mutant HTT-induced ER stress via activation of the S1R, providing additional evidence of its therapeutic potential as a selective and potent S1R agonist

3. Sigma-1 Receptor (S1R) Interaction with Cholesterol: Mechanisms of S1R Activation and Its Role in Neurodegenerative Diseases - Zhemkov et al., International Journal of Molecular Sciences, 2021

* This review article investigates the biological interactions between the S1R and cholesterol and looks into the therapeutic benefit of pridopidine as a selective and potent S1R agonist in neurodegenerative diseases.

Pridopidine is a first-in-class small molecule in clinical development for the treatment of HD and Amyotrophic Lateral Sclerosis (ALS). It is a highly selective and potent S1R agonist in clinical development for both indications. Pridopidine demonstrates neuroprotective effects in preclinical models of HD, ALS and other neurodegenerative diseases.

Michael R. Hayden, MD, PhD, CEO of Prilenia and world-renowned expert in Huntington's Disease research, commented:

" These new insights on pridopidine and how it affects S1R continues to advance our knowledge on its mechanism of action, which supports the development of this drug for HD and ALS."

Pridopidine is a safe and well tolerated orally administered drug currently being assessed in a Global Phase 3 study (PROOF-HD), evaluating the effect of pridopidine 45 mg bid on Total Functional Capacity (TFC) in patients with early-stage HD. The study is being conducted in collaboration with the Huntington Study Group (HSG). Pridopidine is also being assessed in the first platform trial for ALS in collaboration with the Healey Center for ALS at Mass General Hospital.

Staying up all night, working nonstop, eating on the run and skipping meals are often telltale signs of starting a new business. But research shows this constant hustle - which is often glorified as the key to success - can have a negative impact not only on an entrepreneur's health and well-being but also his or her business.

New research led by UCF assistant professor of management Jeff Gish suggests that engaging in recovery may help entrepreneurs reduce the negative impact of stress.

"Entrepreneurs who work really hard and grind on their business and who most need to recover, don't take a break," says Gish, who also has studied how lack of sleep impacted entrepreneurs' decision-making ability. "That incessant grind, fueled by the autonomy that accompanies self-employment, hinders or hampers them from taking time to recover. This creates a tension between the good and bad associated with entrepreneurial careers, which leads to strange well-being outcomes. We're trying to fix that."

Gish builds on his previous research that documented the link between entrepreneurial well-being and the stressors that affect it. In this study, which was recently published in the scholarly journal Entrepreneurship Theory and Practice, Gish proposes recovery interventions to enhance entrepreneurial well-being.

To help entrepreneurs recover, Gish and his co-authors recommend three recovery-intervention categories they've dubbed the 3 Rs: Respite, Reappraisal and Regimen.

"Respite is just taking a break or pushing 'pause' on work. Reappraisal is changing how you think about stress," says Gish, noting that writing in a journal can help someone understand how they look at stress or failure and then reframe it. "And the last one is regimen, just adding structure to respite and reappraisal."

Gish recommends setting work aside, even for just a few minutes, to take a walk, listen to music or engage in other non-work-related activities. The study notes that even micro-breaks, which may span just 5-10 minutes, can provide physical and mental relief from stress, aid in recovery and boost productivity.

"If you're always working and always on, that can impair recovery and eventually harm a host of well-being outcomes," he says.

The study, a comprehensive review of the literature around entrepreneur well-being, stressors and their effects, also offers guidance on how entrepreneurs can reframe how they look at self-care and recovery, and then how to build it into their routines.

Gish joined UCF's College of Business in 2019. Co-authors for the research are Amanda Jasmine Williamson, lecturer in Innovation and Strategy at University of Waikato in New Zealand; and Ute Stephan, professor of entrepreneurship, King's College London, and Technische Universität Dresden.

MAY 24, 2021, NEW YORK - A Ludwig Cancer Research study has discovered how to revive a powerful but functionally inert subset of anti-cancer immune cells that are often found within tumors for cancer therapy.

Led by Ludwig Lausanne's Ping-Chih Ho and Li Tang of the École Polytechnique Fédérale de Lausanne, the study describes how an immune factor known as interleukin-10 orchestrates the functional revival of "terminally exhausted" tumor-infiltrating T lymphocytes (TILs), which have so far proved impervious to stimulation by immunotherapies. It also demonstrates that the factor, when applied in combination with cell therapies, can eliminate tumors in mouse models of melanoma and colon cancer. The findings are reported in the current issue of Nature Immunology.

"We've found, for the first time, that terminally exhausted TILs can be directly rejuvenated so that their potent anti-cancer activity is restored, and that this rejuvenation is accomplished through the metabolic reprogramming of the cells induced by interleukin-10," said Ho, associate member of the Ludwig Institute for Cancer Research, Lausanne.

Deprived of oxygen and vital nutrients within tumors, the TILs most capable of killing cancer cells are typically pushed into a stubbornly sluggish state known as exhaustion. Recent research has identified two distinct types of exhausted TILs. One, known as "progenitor exhausted" TILs, can recognize cancer cells with nominal efficiency and proliferate in response to the immunotherapy PD-1 blockade. But it is their descendants, "terminally exhausted" TILs, that are best equipped to detect and destroy cancer cells. They are, however, functionally disabled, prone to self-destruction and utterly incapable of proliferation.

"Even PD-1 blockade cannot restore the function of these terminally exhausted TILs," said Ho. "In fact, many patients do not respond to PD-1 blockade because their tumors lack progenitor exhausted TILs and have only terminally exhausted TILs. This is why researchers are looking for ways to revive terminally exhausted T cells for cancer therapy."

Three lines of evidence prompted the current study. First, Ho and his team recently showed that terminally exhausted TILs could be functionally revived by restoring the health of their mitochondria--the bean-shaped organelles in cells that generate energy and help regulate metabolism. Second, IL-10 is known to stimulate anti-cancer immune responses and has been tested as a therapy for lung cancer in an early phase clinical trial, albeit with mixed results. Finally, IL-10 was recently found to restore mitochondrial fitness and reprogram the metabolism of immune cells known as macrophages.

Ho and his colleagues wondered whether IL-10 might similarly influence terminally exhausted TILs.

To find out, they added an engineered, long-lived version of IL-10 (IL-10/Fc) to adoptive cell therapy (ACT)--the infusion of tumor-targeting T cells to treat cancer--and tested the combination in a mouse model of melanoma. The treatment boosted the number and functionality of terminally exhausted TILs and led to tumor regression and cures in 90% of treated mice, compared to limited regressions with IL-10/Fc alone and none with ACT alone. Notably, 80% of surviving mice developed an immune memory for the cancer, spontaneously rejecting the same tumors implanted two months after therapy.

"This suggests that if IL-10 is added to ACT, it could confer long-term protection from cancer growth," said Ho.

The researchers also tested IL-10/Fc on CAR-T cells, which are engineered to target cancer cells bearing specific molecular markers. IL-10/Fc treated CAR-T cells induced complete cures of roughly 90% of mice implanted with colon cancer tumors.

Ho, Tang and colleagues found that IL-10/Fc specifically acts on terminally exhausted TILs, not on progenitor exhausted TILs. They also showed it reprograms the metabolism of terminally exhausted TILs--beginning with the process they employ to extract energy from nutrients. That, in turn, leads to sweeping changes in their gene expression programs, which drives their functional re-activation and proliferation. IL-10/Fc had the same effect on human TILs, and on CAR-T cells as well.

"With IL-10, we reset the energy-generation program of the most exhausted soldiers of the anti-cancer immune response and revived their ability to kill tumor cells," said Ho.

The researchers are now investigating the precise mechanisms by which metabolic reprogramming alters gene expression patterns in the terminally exhausted TILs. They are also conducting preclinical studies to advance the application of their discoveries to human cancer therapy.

An international research group involving the Institute of Molecular and Cellular Biology of Plants (IBMCP), a joint centre of the Universitat Politècnica de València (UPV) and the Spanish National Research Council (CSIC), has discovered that a genetic mechanism, called CHLORAD, which is involved in the ageing of plant leaves, also plays a decisive role in the tomato ripening process. Thus, tomatoes with an activated CHLORAD system turn red more quickly, and accumulate more lycopene, a compound beneficial to health. The results, which have been published in the latest issue of the journal Nature Plants, will lead to better quality tomatoes.

The ripening of most fleshy fruits gives them attractive colours and smells, which is a trick of the plant to spread its seeds more widely and colonise new territories. In tomatoes, ripening changes their colour from green to orange and red. The green is due to the presence of chlorophyll (the photosynthesis pigment) in the chloroplasts of the immature fruits. When they ripen, the chloroplasts (the organs in charge of photosynthesis) lose that chlorophyll and produce large quantities of other pigments, called carotenoids.

Tomato carotenoids are orange (due to beta-carotene) and red (due to lycopene), which causes the fruit to change colour when ripe. In addition, these carotenoids form aromas that contribute to the characteristic smell of ripe tomatoes. For all this to happen, the chloroplasts need to be transformed into a new type of carotenoid storage compartment, called a chromoplast.

Until recently, it was not known how the tomato plant controls the transformation of chloroplasts into chromoplasts. Now, a research group from the University of Oxford (UK) in collaboration with the Valencian Institute of Molecular and Cell Biology of Plants (IBMCP) has unravelled part of this mystery, in an article published in the journal Nature Plants.

The key to this work comes from Arabidopsis, a plant used as a study model that does not develop chromoplasts naturally, but does transform its chloroplasts during a process -known as leaf senescence- in which the leaves age, lose their chlorophyll and stop photosynthesising. During this process, a molecular mechanism called CHLORAD removes complexes in the outer layer of chloroplasts that import proteins needed for photosynthesis.

Tomatoes that turn red sooner

Researchers have found that the CHLORAD system also works during tomato ripening. When activated, it prevents the import of photosynthetic proteins, but promotes the incorporation of other proteins necessary for the production and storage of carotenoids during the transformation of chloroplasts into chromoplasts. Thus, fruits with an activated CHLORAD system turn red sooner and accumulate more of the health-promoting carotenoid lycopene, while fruits with a deficient CHLORAD system take longer to ripen.

"In addition to better understanding how chloroplasts are transformed into chromoplasts, we now know that this process not only regulates fruit pigmentation, but also affects many other aspects linked to ripening that influence the firmness or the aroma of tomatoes," says Manuel Rodríguez Concepción, a CSIC researcher at the IBMCP who is participating in this study. The challenge now is to understand the connections between these mechanisms in order to produce tomatoes of a higher commercial and nutritional quality without sacrificing their characteristic colour, aroma and flavour.

A new study shows that the current rate of biodiversity decline in freshwater ecosystems outcompetes that at the end-Cretaceous extinction that killed the dinosaurs: damage now being done in decades to centuries may take millions of years to undo.

The current biodiversity crisis, often called the 6th mass extinction, is one of the critical challenges we face in the 21st century. Numerous species are threatened with extinction, mostly as a direct or indirect consequence of human impact. Habitat destruction, climate change, overexploitation, pollution and invasive species are among the main causes for Earth's biota to decline rapidly.

To investigate the tempo of extinction and predict recovery times, an international team of evolutionary biologists, paleontologists, geologists and modelers led by the Justus Liebig University Giessen compared today's crisis with the previous, 5th mass extinction event. That event was the result of an asteroid impact 66 million years ago, eradicating about 76% of all species on the planet, including entire animal groups such as the dinosaurs. Focusing on freshwater biota, which are among the World's most threatened, the research team gathered a large dataset containing 3,387 fossil and living snail species of Europe covering the past 200 million years. The scientists estimated rates of speciation and extinction to assess the speed at which species come and go and predict recovery times.

The results of the study, which are recently published in the journal Communications Earth & Environment, are alarming. While already the extinction rate during the 5th mass extinction was considerably higher than previously believed for freshwater biota, it is drastically overshadowed by the predicted future extinction rate of the current 6th mass extinction event. On average the predicted rate was three orders of magnitudes higher than during the time the dinosaurs went extinct. Already by 2120 a third of the living freshwater species may have vanished.

The pace at which we lose species today is unprecedented and has not even been reached during major extinction crises in the past. "Losing species entails changes in species communities and, in the long run, this affects entire ecosystems. We rely on functioning freshwater environments to sustain human health, nutrition and fresh water supply", says the lead author of the study, Dr. Thomas A. Neubauer.

The trend the scientists revealed for the 5th mass extinction event has another, potentially even more dire prospect for the future. Although the cause for the rising extinction - an asteroid impact on the Yucatán Peninsula in Mexico - was a short event in geological time scales, the extinction rate remained high for approximately five million years. Afterwards followed an even longer period of recovery. It took altogether nearly 12 million years until the balance was restored between species originating and going extinct.

"Even if our impact on the world's biota stops today, the extinction rate will likely stay high for an extended period of time. Considering that the current biodiversity crisis advances much faster than the mass extinction event 66 million years ago, the recovery period may be even longer", says Neubauer. "Despite our short existence on Earth, we have assured that the effects of our actions will outlast us by millions of years."

[Highlights]

- Integrated cyber attack analysis platform "NIRVANA Kai" newly supports IPv6 and enhances its functions.

- Observation of IPv6 communications, collection of IPv6-related alerts, and real-time visualization of IPv6 networks.

- Expected to simplify security operations in IPv6 networks.

[Abstract]

The Cybersecurity Laboratory of the National Institute of Information and Communications Technology (NICT, President: TOKUDA Hideyuki, Ph.D.) has enhanced its cyber attack integrated analysis platform "NIRVANA Kai" to support the Internet Protocol version 6 (IPv6), the successor to IPv4. NIRVANA Kai has succeeded in real-time visualization of packets flowing in the vast address space of IPv6 for the first time in the world. Until now, NIRVANA Kai has only been able to observe and analyze IPv4 communications, however, with the new support for IPv6 communications, it is expected to be useful for security measures for more diverse and extensive networks.

[Achievements]

NIRVANA revision has been enhanced to support IPv6 in all parts of the system (communication observation, alert collection, visualization, etc.). In particular, the visualization section has succeeded in efficiently visualizing the vast IPv6 address space by dynamically adding active IP address blocks where communication has been observed (see Figures 1 to 3). In addition, an indicator has been newly implemented to improve the visibility of the current position in the hierarchical structure of the IPv6 address space (see the rightmost part of Figure 2). Furthermore, IPv6-related alert information issued by security appliances is also supported, and filtering by IPv6 address is now possible (see Figure 2).

[Future Prospects]

With NIRVANA revision supporting IPv6 communication, the application range of the system will be significantly expanded, and security operations in IPv6 networks will be simplified.