Category: Science

A compound found in many plants inhibits the growth of drug-resistant Candida fungi, including its most virulent species, Candida auris, in the lab, a study finds.

The journal ACS Infectious Diseases has published a paper on the discovery.

Laboratory-dish experiments showed that the natural compound, a water-soluble tannin known as PGG, blocks 90% of the growth in four different species of Candida fungi. The researchers also discovered how PGG inhibits the growth: It grabs up iron molecules, essentially starving the fungi of an essential nutrient.

By starving the fungi rather than attacking it, the PGG mechanism does not promote the development of further drug resistance, unlike existing antifungal medications. Laboratory-dish experiments also showed minimal toxicity of PGG to human cells.

“Drug-resistant fungal infections are a growing health care problem but there are few new antifungals in the drug-development pipeline,” says Cassandra Quave, senior author of the study and associate professor in Emory School of Medicine’s department of dermatology and the Center for the Study of Human Health. “Our findings open a new potential approach to deal with these infections, including those caused by deadly Candida auris.”

C. auris is often multidrug-resistant and has a high mortality rate, leading the Centers for Disease Control and Prevention (CDC) to label it a serious global health threat.

“It’s a really bad bug,” says Lewis Marquez, first author of the study and a graduate student in the molecular systems and pharmacology program. “Between 30 to 60% of the people who get infected with C. auris end up dying.”

Candida is a yeast often found on the skin and in the digestive tract of healthy people. Some species, such as Candida albicans, occasionally grow out of control and cause mild infections in people.

In more serious cases, Candida can invade deep into the body and cause infections in the bloodstream or organs such as the kidney, heart, or brain. Immunocompromised people, including many hospital patients, are most at risk for invasive Candida infections, which are rapidly evolving drug resistance.

In 2007, the new Candida species, C. auris, emerged in a hospital patient in Japan. Since then, C. auris has caused health care-associated outbreaks in more than a dozen countries around the world with more than 3,000 clinical cases reported in the United States alone.

An ethnobotany approach

Quave is an ethnobotanist, studying how traditional people have used plants for medicine to search for promising new candidates for modern-day drugs. Her lab curates the Quave Natural Product Library, which contains 2,500 botanical and fungal natural products extracted from 750 species collected at sites around the world.

“We’re not taking a random approach to identify potential new antimicrobials,” Quave says. “Focusing on plants used in traditional medicines allows us to hone in quickly on bioactive molecules.”

Previously, the Quave lab had found that the berries of the Brazilian peppertree, a plant used by traditional healers in the Amazon for centuries to treat skin infections and some other ailments, contains a flavone-rich compound that disarms drug-resistant staph bacteria.

Screens by the Quave lab had also found that the leaves of the Brazilian peppertree contain PGG, a compound that has shown antibacterial, anticancer, and antiviral activities in previous research.

PPG vs. pathogens

A 2020 study by the Quave lab, for instance, found that PGG inhibited growth of Carbapenem-resistant Acinetobacter baumannii, a bacterium that infects humans and is categorized as one of five urgent threats by the CDC.

The Brazilian peppertree, an invasive weed in Florida, is a member of the poison ivy family.

“PGG has popped up repeatedly in our laboratory screens of plant compounds from members of this plant family,” Quave says. “It makes sense that these plants, which thrive in really wet environments, would contain molecules to fight a range of pathogens.”

The Quave lab decided to test whether PGG would show antifungal activity against Candida.

Laboratory-dish experiments demonstrated that PGG blocked around 90% of the growth in 12 strains from four species of Candida: C. albicans, multidrug-resistant C. auris, and two other multidrug-resistant non-albicans Candida species.

PGG is a large molecule known for its iron-binding properties. The researchers tested the role of this characteristic in the antifungal activity.

“Each PGG molecule can bind up to five iron molecules,” Marquez explains. “When we added more iron to a dish, beyond the sequestering capacity of the PGG molecules, the fungi once again grew normally.”

Dish experiments also showed that PGG was well-tolerated by human kidney, liver, and epithelial cells.

“Iron in human cells is generally not free iron,” Marquez says. “It is usually bound to a protein or is sequestered inside enzymes.”

Next steps

Previous animal studies on PGG have found that the molecule is metabolized quickly and removed from the body. Instead of an internal therapy, the researchers are investigating its potential efficacy as a topical antifungal.

“If a Candida infection breaks out on the skin of a patient where a catheter or other medical instrument is implanted, a topical antifungal might prevent the infection from spreading and entering into the body,” Marquez says.

As a next step, the researchers will test PGG as a topical treatment for fungal skin infections in mice.

Meanwhile, Quave and Marquez have applied for a provisional patent for the use of PGG for the mitigation of fungal infections.

“These are still early days in the research, but another idea that we’re interested in pursuing is the potential use of PGG as a broad-spectrum microbial,” Quave says. “Many infections from acute injuries, such as battlefield wounds, tend to be polymicrobial so PGG could perhaps make a useful topical treatment in these cases.”

Scientists from the University of Toronto are coauthors of the paper, including Yunjin Lee, Dustin Duncan, Luke Whitesell, and Leah Cowen. Whitesell and Cowen are co-founders and shareholders in Bright Angel Therapeutics, a platform company for development of antifungal therapeutics, and Cowen is a science advisor for Kapoose Creek, a company that harnesses the therapeutic potential of fungi.

The work had support from the National Institutes of Health; National Center for Complementary and Integrative Health; the Jones Center at Ichauway; the CIHR Frederick Banting and Charles Best Canada Graduate Scholarship; and the Canadian Institutes of Health Research Foundation.

Source: Emory University

The rate at which large cosmic structures grow is slower than Einstein’s Theory of General Relativity predicts, report researchers.

They also show that as dark energy accelerates the universe’s global expansion, the suppression of the cosmic structure growth that the researchers see in their data is even more prominent than what the theory predicts. Their results appear in Physical Review Letters.

As the universe evolves, scientists expect large cosmic structures to grow at a certain rate: dense regions such as galaxy clusters would grow denser, while the void of space would grow emptier.

Galaxies are threaded throughout our universe like a giant cosmic spider web. Their distribution is not random. Instead, they tend to cluster together. In fact, the whole cosmic web started out as tiny clumps of matter in the early universe, which gradually grew into individual galaxies, and eventually galaxy clusters and filaments.

“Throughout the cosmic time, an initially small clump of mass attracts and accumulates more and more matter from its local region through gravitational interaction. As the region becomes denser and denser, it eventually collapses under its own gravity,” says Minh Nguyen, lead author of the study and postdoctoral research fellow in the University of Michigan department of physics.

“So as they collapse, the clumps grow denser. That is what we mean by growth. It’s like a fabric loom where one-, two-, and three-dimensional collapses look like a sheet, a filament, and a node. The reality is a mixture of all three cases, and you have galaxies living along the filaments while galaxy clusters—groups of thousands of galaxies, the most massive objects in our universe bounded by gravity—sit at the nodes.”

The universe is not only made of matter. It also likely contains a mysterious component called dark energy. Dark energy accelerates the expansion of the universe on a global scale. As dark energy accelerates the expansion of the universe, it has the opposite effect on large structures.

“If gravity acts like an amplifier enhancing matter perturbations to grow into large-scale structure, then dark energy acts like an attenuator damping these perturbations and slowing the growth of structure,” Nguyen says. “By examining how cosmic structure has been clustering and growing, we can try to understand the nature of gravity and dark energy.”

Nguyen, physics professor Dragan Huterer, and graduate student Yuewei Wen examined the temporal growth of large-scale structure throughout cosmic time using several cosmological probes.

First, the team used what’s called the cosmic microwave background. The cosmic microwave background, or CMB, is composed of photons emitted just after the Big Bang. These photons provide a snapshot of the very early universe. As the photons travel to our telescopes, their path can become distorted, or gravitationally lensed, by large-scale structure along the way. Examining them, the researchers can infer how structure and matter between us and the cosmic microwave background are distributed.

Nguyen and colleagues took advantage of a similar phenomenon with weak gravitational lensing of galaxy shapes. Light from background galaxies is distorted through gravitational interactions with foreground matter and galaxies. The cosmologists then decode these distortions to determine how the intervening matter is distributed.

“Crucially, as the CMB and background galaxies are located at different distances from us and our telescopes, galaxy weak gravitational lensing typically probes matter distributions at a later time compared to what is probed by CMB weak gravitational lensing,” Nguyen says.

To track the growth of structure to an even later time, the researchers further used motions of galaxies in the local universe. As galaxies fall into the gravity wells of the underlying cosmic structures, their motions directly track structure growth.

“The difference in these growth rates that we have potentially discovered becomes more prominent as we approach the present day,” Nguyen says. “These different probes individually and collectively indicate a growth suppression. Either we are missing some systematic errors in each of these probes, or we are missing some new, late-time physics in our standard model.”

The findings potentially address the so-called S8 tension in cosmology. S8 is a parameter that describes the growth of structure. The tension arises when scientists use two different methods to determine the value of S8, and they do not agree. The first method, using photons from the cosmic microwave background, indicates a higher S8 value than the value inferred from galaxy weak gravitational lensing and galaxy clustering measurements.

Neither of these probes measures the growth of structure today. Instead, they probe structure at earlier times, then extrapolate those measurements to present time, assuming the standard model. Cosmic microwave background probes structure in the early universe, while galaxy weak gravitational lensing and clustering probe structure in the late universe.

The researchers’ findings of a late-time suppression of growth would bring the two S8 values into perfect agreement, according to Nguyen.

“We were surprised with the high statistical significance of the anomalous growth suppression,” Huterer says. “Honestly, I feel like the universe is trying to tell us something. It is now the job of us cosmologists to interpret these findings.

“We would like to further strengthen the statistical evidence for the growth suppression. We would also like to understand the answer to the more difficult question of why structures grow slower than expected in the standard model with dark matter and dark energy. The cause of this effect may be due to novel properties of dark energy and dark matter, or some other extension of General Relativity and the standard model that we have not yet thought of.”

Source: University of Michigan

New findings underscore the ways that being a Black mother in the United States involves navigating aspects of parenthood that are explicitly tied to dealing with anti-Black racism.

“All mothers experience stress; but Black mothers in the US experience additional stresses specifically related to parenting and racism,” says Mia Brantley, author of the study and an assistant professor of sociology at North Carolina State University. “That has consequences for the health and well-being of Black mothers. If we want to develop ways to support Black moms and Black families, we need to have a deeper understanding of the challenges facing Black mothers—and how Black mothers respond to those challenges.”

For this qualitative study, Brantley conducted in-depth interviews with 35 Black mothers from across the US. All of the study participants had at least one child between the ages of 10 and 24. The interviews were designed to collect information about how Black women think about motherhood and mothering, as well as how Black mothers feel race and racism influences both their parenting and the lives of their children.

“There is a broad understanding that motherhood is, while rewarding, also a demanding responsibility,” Brantley says. “This study found that, while Black mothers share many of the same concerns as other mothers, Black motherhood is distinct. That’s because—in addition to wanting their children to succeed—Black mothers also take steps to both protect their children from racism and help their children learn to navigate a society where they will experience anti-Black racism.”

Brantley categorizes the ways racism affects Black motherhood into three areas: protective mothering, resistance mothering, and encumbered mothering.

Protective mothering refers to practices designed to help Black children avoid racism. Specifically, Black mothers will often restrict children’s activities or behaviors in an attempt to reduce the likelihood that that their children—particularly sons—will face racist comments or actions. Black mothers also take steps to encourage agency—particularly for daughters—so that their children feel able to stand up for themselves.

• Resistance mothering refers to efforts to promote positive self-image, with the goal of combatting racist stereotypes their children encounter outside of the home. These activities might include educating children about Black artists, leaders, and accomplishments.
• “Resistance mothering is really about empowering Black children and parents, so that they take pride in themselves and their culture,” Brantley says.
• Encumbered mothering refers to the fact that Black mothers feel the need to be constantly hyperaware of the risks that racism poses to their children.

“Black mothers report that they are unable to fully enjoy and celebrate the accomplishments of their children, because they can’t ‘turn off’ their fears about how racist behavior may affect their kids,” Brantley says. “Black mothers feel that they always have to deal with preconceived notions about Black mothers and children, and that society essentially gives Black women no room for error.

“We talk about motherhood as universal, but all mothers do not experience motherhood in the same way,” Brantley says. “Black women face stresses that are unique to their experiences as mothers—stresses that continue into their children’s adulthood. While Black mothers are taking steps to protect their children, the stress of doing so may carry costs for the health and well-being of Black women.

“This study gives us a framework for understanding, studying, and talking about Black motherhood. And, hopefully, that gives us a starting point for a more in-depth analysis of the toll that motherhood takes on Black women, and how we—as a society—can do more to support these women.”

The study appears in the journal Social Problems. The work took place support from the National Institute on Aging, the Ohio State University Institute for Population Research, and a University of South Carolina SPARC grant.

Source: NC State

A new review paper suggests that scrambler therapy, a noninvasive pain treatment, can yield significant relief for approximately 80–90% of patients with chronic pain.

The paper also indicates that scrambler therapy may be more effective than another noninvasive therapy, transcutaneous electrical nerve stimulation, or TENS.

“It’s like pressing Control-Alt-Delete about a billion times.”

The researchers’ write-up appears in the New England Journal of Medicine.

Scrambler therapy, approved by the United States Food and Drug Administration in 2009, administers electrical stimulation through the skin via electrodes placed in areas of the body above and below where chronic pain is felt.

The goal is to capture the nerve endings and replace signals from the area experiencing pain with signals coming from adjacent areas experiencing no pain, thereby “scrambling” the pain signals sent to the brain, explains primary study author Thomas Smith, professor of palliative medicine at the Johns Hopkins Kimmel Cancer Center and a professor of oncology and medicine at the Johns Hopkins University School of Medicine.

All chronic pain and almost all nerve and neuropathic pain result from two things, says Smith, who also is the director of palliative medicine for Johns Hopkins Medicine:

• Pain impulses coming from damaged nerves that send a constant barrage up to pain centers in the brain.
• The failure of inhibitory cells to block those impulses and prevent them from becoming chronic.

“If you can block the ascending pain impulses and enhance the inhibitory system, you can potentially reset the brain so it doesn’t feel chronic pain nearly as badly,” Smith says. “It’s like pressing Control-Alt-Delete about a billion times.”

Many patients “get really substantial relief that can often be permanent,” he says. Treatment consists between three and 12 half-hour sessions.

As a physician who treats chronic pain, Smith says, “scrambler therapy is the most exciting development I have seen in years—it’s effective, it’s noninvasive, it reduces opioid use substantially, and it can be permanent.”

TENS therapy also administers low-intensity electrical signals through the skin, but it uses a pair of electrodes at the sites of pain. Pain relief often disappears when or soon after the electrical impulses are turned off, Smith says. A study cited in the review paper evaluated the impact of TENS in 381 randomized clinical trials, and the authors found a non-statistically significant difference in pain relief between TENS and a placebo procedure.

Source: Johns Hopkins University

Researchers have genetically engineered a marine microorganism to break down plastic in salt water, according to a new study.

Specifically, the modified organism can break down polyethylene terephthalate (PET), a plastic used in everything from water bottles to clothing that is a significant contributor to microplastic pollution in oceans.

“This is exciting because we need to address plastic pollution in marine environments,” says Nathan Crook, an assistant professor of chemical and biomolecular engineering at North Carolina State University and corresponding author of the paper published in AIChE Journal.

“One option is to pull the plastic out of the water and put it in a landfill, but that poses challenges of its own. It would be better if we could break these plastics down into products that can be re-used. For that to work, you need an inexpensive way to break the plastic down. Our work here is a big step in that direction.”

To address this challenge, the researchers worked with two species of bacteria. The first bacterium, Vibrio natriegens, thrives in saltwater and is remarkable, in part because it reproduces very quickly. The second bacterium, Ideonella sakaiensis, is remarkable because it produces enzymes that allow it to break down PET and eat it.

The researchers took the DNA from I. sakaiensis that is responsible for producing the enzymes that break down plastic, and incorporated that genetic sequence into a plasmid.

Plasmids are genetic sequences that can replicate in a cell, independent of the cell’s own chromosome. In other words, you can sneak a plasmid into a foreign cell, and that cell will carry out the instructions in the plasmid’s DNA. That’s exactly what the researchers did here.

By introducing the plasmid containing the I. sakaiensis genes into V. natriegens bacteria, the researchers were able to get V. natriegens to produce the desired enzymes on the surface of their cells. The researchers then demonstrated that V. natriegens was able to break down PET in a saltwater environment at room temperature.

“This is scientifically exciting because this is the first time anyone has reported successfully getting V. natriegens to express foreign enzymes on the surface of its cells,” Crook says.

“From a practical standpoint, this is also the first genetically engineered organism that we know of that is capable of breaking down PET microplastics in saltwater,” says Tianyu Li, a PhD student and the paper’s first author.

“That’s important, because it is not economically feasible to remove plastics from the ocean and rinse high concentration salts off before beginning any processes related to breaking the plastic down.”

“However, while this is an important first step, there are still three significant hurdles,” Crook says.

“First, we’d like to incorporate the DNA from I. sakaiensis directly into the genome of V. natriegens, which would make the production of plastic-degrading enzymes a more stable feature of the modified organisms. Second, we need to further modify V. natriegens so that it is capable of feeding on the byproducts it produces when it breaks down the PET. Lastly, we need to modify the V. natriegens to produce a desirable end product from the PET—such as a molecule that is a useful feedstock for the chemical industry.

“Honestly, that third challenge is the easiest of the three,” says Crook. “Breaking down the PET in saltwater was the most challenging part.

“We are also open to talking with industry groups to learn more about which molecules would be most desirable for us to engineer the V. natriegens into producing,” Crook says. “Given the range of molecules we can induce the bacteria to produce, and the potentially vast scale of production, which molecules could industry provide a market for?”

The National Science Foundation supported the work.

Source: NC State

A new molecularly engineered hydrogel that can create clean water using just the energy from sunlight.

The researchers were able to pull water out of the atmosphere and make it drinkable using solar energy, in conditions as low as 104 degrees, aligning with summer weather in Texas and other parts of the world.

That means people in places with excess heat and minimal access to clean water could someday simply place a device outside, and it would make water for them, with no additional effort necessary.

“With our new hydrogel, we’re not just pulling water out of thin air. We’re doing it extremely fast and without consuming too much energy,” says Guihua Yu, a materials science and engineering professor in the Cockrell School of Engineering’s Walker Department of Mechanical Engineering and Texas Materials Institute at the University of Texas at Austin.

“What’s really fascinating about our hydrogel is how it releases water. Think about a hot Texas summer—we could just use our temperatures’ natural ups and downs, no need to crank up any heaters.”

The device can produce between 3.5 and 7 kilograms (about 7.7 lbs to 15.4 lbs) of water per kilogram of gel materials, depending on humidity conditions.

A significant feature of this research is the hydrogel’s adaptability into microparticles called “microgels.” These microgels unlock the speed and efficiency improvements that bring this device much closer to reality.

“By transforming the hydrogel into micro-sized particles, we can make the water capture and release ultrafast,” says Weixin Guan, a graduate student in Yu’s lab and one of the lead authors of the study, published in the Proceedings of the National Academy of Sciences.

“This offers a new, highly efficient type of sorbents that can significantly enhance the water production by multiple daily cycling.”

The researchers are pursuing additional improvements to the technology, with an eye toward transforming it into a commercial product. One focus area is optimizing the engineering of the microgels to further improve efficiency.

Scaling up is an important next step. The researchers aim to translate their work into tangible and scalable solutions that can be used worldwide as a low-cost, portable method of creating clean drinking water. This could be life-changing for countries such as Ethiopia, where almost 60% of the population lacks basic access to clean water.

“We developed this device with the ultimate goal to be available to people around the world who need quick and consistent access to clean, drinkable water, particularly in those arid areas,” says Yaxuan Zhao, a graduate student in Yu’s lab.

The team is working on other versions of the device made from organic materials, which would reduce costs for mass production. This transition to more commercially viable designs comes with its own challenges in scaling production of the sorbent that allows moisture absorption and in maintaining durability for the product’s lifespan. Research is also focused on making the devices portable for various application scenarios.

The Norman Hackerman Award in Chemical Research from the Welch Foundation and the Camille Dreyfus Teacher-Scholar Award funded the work.

Source: UT Austin

A new brain organoid model lets researchers investigate the origins of autism.

Organoids are microtissue spheroids that are grown from stem cells and have a similar structure to real organs.

With them, and with a new method for modifying genes within these organoids using the CRISPR-Cas gene scissors, the researchers found out which genetic networks in which cell types in the brain are responsible for the development of autism.

“Our model offers unparalleled insight into one of the most complex disorders affecting the human brain and brings some much needed hope to clinical autism research,” says Jürgen Knoblich, professor and scientific director of the Institute of Molecular Biotechnology (IMBA) of the Austrian Academy of Sciences in Vienna and coauthor of the study in Nature.

This new method enabled the researchers to genetically modify the cells of a brain organoid in a mosaic-like fashion and then study them systematically. Specifically, the scientists altered one of 36 different genes associated with autism in each of the individual cells and studied the resulting effects. “We can see the consequences of every mutation in a single experiment, thus reducing the analysis time drastically when compared to conventional methods,” Knoblich says.

The new method was developed by researchers at the IMBA in Vienna, based on previous methods. In the current study, the group led by Barbara Treutlein, professor of quantitative developmental biology at ETH Zurich, incorporated the computer-assisted analysis of the raw research data: changing multiple genes in parallel in a human organoid and analyzing the resulting effects at the level of thousands of individual cells creates a vast amount of data.

In human disease research, organoids offer advantages over research using lab animals: unlike in lab animals, human genes and cells can be studied in organoids. These advantages are particularly significant in neuroscience, as the specific processes responsible for the development of the human cerebral cortex are unique to the human brain.

Neurodevelopmental disorders in humans are due in part to these human-specific processes in brain development. For example, many human genes that confer an increased risk for an autism spectrum disorder are genes that are critical for cortex development.

Previous studies have shown a causal link between certain gene mutations and autism. However, scientists still don’t understand how these mutations lead to defects in brain development and the expression of autism spectrum disorders. Due to the uniqueness of human brain development, the utility of animal models in this case is limited. “Only a human model of the brain like the one we used can reproduce the complexity and particularities of the human brain,” Knoblich says.

In their organoid model, the researchers were able to show that the genetic changes that are typical for autism affected mainly certain types of neural precursor cells. These are the founder cells from which neurons are created. “This suggests that molecular changes occur at an early stage in fetal brain development that ultimately lead to autism,” says Chong Li, a postdoc at IMBA and one of the study’s two lead authors. “Some cell types we identified are more vulnerable in autism and should receive more attention in future research.”

In addition, the scientists reveal that there are connections among the 36 genes they studied that confer a high risk for autism: “Using a program we developed, we were able to show that these genes are connected to each other through a gene regulation network, and that they interact with each other and have similar effects in the cells,” says Jonas Fleck, a doctoral student in Treutlein’s group and the other lead author of the study.

To test whether the results from the organoid model actually apply to autistic people, the researchers teamed up with clinicians at the Medical University of Vienna to produce brain organoids from two stem cell samples from affected individuals. They found that the organoid data closely matched clinical observations in the affected individuals.

The researchers emphasize that their technology for changing organoid cells in a mosaic-like fashion can also be used for organoids of other human organs and to study other diseases. This is a new research tool for rapidly examining a large number of disease-associated genes. “This technology thus helps to obtain relevant research results directly with human organoids in cell culture,” Treutlein says. “What’s more, human organoid disease models can also be used to test drug efficacy, which can help reduce animal testing.”

Source: ETH Zurich via IMBA

A study begins to address a longstanding question in condensed matter physics about whether disorder mimics or destroys the quantum liquid state in a prominent compound.

Quantum spin liquids are difficult to explain and even harder to understand.

To start, they have nothing to do with everyday liquids, like water or juice, but everything to do with special magnets and how they spin. In regular magnets, when the temperature drops, the spin of the electrons essentially freezes and forms a solid piece of matter. In quantum spin liquids, however, the spin of electrons doesn’t freeze—instead the electrons stay in a constant state of flux, as they would in a free-flowing liquid.

Quantum spin liquids are one of the most entangled quantum states conceived to date, and their properties are key in applications that scientists say could catapult quantum technologies. Despite a 50-year search for them and multiple theories pointing to their existence, no one has ever seen definitive evidence of this state of matter. In fact, researchers may never see that evidence because of the difficulty of directly measuring quantum entanglement, a phenomenon Albert Einstein famously termed “spooky action at a distance.” This is where two atoms become linked and able to exchange information no matter how far apart they are.

The mystery around quantum spin liquids has led to major questions about this exotic material in condensed matter physics that have to this point gone unanswered. But in a new paper in Nature Communications, a team of physicists begins to shed light on one of the most important questions, and does so by introducing a new phase of matter.

It all comes down to disorder.

Kemp Plumb, an assistant professor of physics at Brown University and senior author of the new study, explains that “all materials on some level have disorder” and that disorder has to do with the number of microscopic ways components of a system can be arranged. An ordered system, like a solid crystal, has very few ways to rearrange it, for instance, while a disordered system, like a gas, has no real structure to it.

In quantum spin liquids, disorder introduces discrepancies that essentially butt heads with the theory behind the liquids. One prevailing explanation was that when disorder is introduced, the material ceases to be a quantum spin liquid and instead is simply a magnet that’s in a state of disorder. “So, the big question was whether the quantum spin liquid state survives in the presence of disorder and if it does survive, how?” Plumb says.

The researchers addressed the question by using some of the brightest X-rays in the world to analyze magnetic waves in the compound they studied for tell-tale signatures that it’s a quantum spin liquid. The measurements showed that not only does the material not magnetically order (or freeze) at low temperatures, but that the disorder that’s present in the system doesn’t mimic or destroy the quantum liquid state.

It does significantly alter it, they find.

“The quantum liquid state sort of survives,” Plumb says. “It doesn’t do what you would expect a normal magnet to do where it just freezes. It stays in this dynamic state, but it’s like a de-correlated version of that dynamic state. Our interpretation right now is the quantum spin liquid is broken up into little puddles throughout the material.”

The findings essentially suggest that the material they looked at, which is one of the prime candidates to be a quantum spin liquid, does appear to be close to one, yet with an additional component. The researchers posit that it’s a quantum spin liquid that is disordered, making it a new phase of disordered matter.

“One thing that could have happened in this material was that it becomes a disordered version of a non-quantum spin liquid state, but our measurements would have would have told us that,” Plumb says. “Instead, our measurements show that it’s something very different.”

The results deepen understanding of how disorder affects quantum systems and how to account for it, which is important as these materials are explored for use in quantum computing.

The work is a part of a long line of research on exotic magnetic states from Plumb’s lab. The study focuses on the compound H3LiIr2O6, a material considered to best fit the archetype for being a special type of quantum spin liquid called a Kitaev spin liquid. Though known not to freeze at cold temperatures, H3LiIr2O6 is notoriously difficult to produce in a lab and is known to have disorder in it, muddying whether it was truly a spin liquid.

The researchers at Brown worked with collaborators at Boston College to synthesize the material and then used the powerful X-ray system at the Argonne National Laboratory in Illinois to zap it with high-energy light. The light excites the magnetic properties in the compound, and the measurements that come from the waves it produces are a workaround for measuring entanglement, because the method offers a way of looking at how light influences the entire system.

The researchers hope next to continue to expand on the work by refining methods, the material itself and looking at different materials.

“The biggest thing going forward is something that we’ve been doing, which is continuing to search the really vast space of materials that the periodic table gives us,” Plumb says. “Now we have a deeper understanding of how the different combinations of elements that we put together can affect the interactions or give rise to different kinds of disorder that will affect the spin liquid. We have more guidance, which is really important because it truly is a really vast search space.”

Support for the work came from the Department of Energy, which operates the Argonne National Laboratory.

Source: Brown University

A high diversity of native tree species can help curb the intensity of invasive non-native tree species, research finds.

Human activity in hotspots of global trade, such as maritime ports, is linked to an increased likelihood of these invasions, report researchers in the journal Nature.

For centuries, human activity has intentionally or unintentionally driven the spread of plant species to areas far outside their native habitat. On average, about 10% of non-native species worldwide become invasive, often causing large ecological and economic consequences for affected regions.

For the first time, a global team of researchers has explored which regions on Earth are most vulnerable to non-native tree invasions. The study combines human and ecological factors to assess the drivers of tree invasion occurrence and severity across the globe.

The study reveals that proximity to human activity—especially maritime ports—emerges as a dominant factor driving the likelihood of invasion. Ports handle tons of goods including plants or seeds from all corners of the globe. The colonization pressure exerted by plant material is, therefore, very high in these regions of high human activity. The closer a forest is to a port, the higher the risk of invasion.

However, ecological factors determine the severity of invasion. Most importantly, native biodiversity helps to buffer the intensity of these invasions. In diverse forests, when most of the available niches are filled by native species, it becomes harder for non-native tree species to spread and proliferate.

The ecological strategy of the invading species is also important in determining which types of trees can invade in different regions. In harsh regions with extreme cold or dry conditions, the researchers found that non-native tree species must be functionally similar to native species to survive in these harsh environments. However, in locations with moderate conditions, non-native trees must be functionally dissimilar to native species in order to survive by functionally differentiating themselves, the non-native species avoid intense competition with native trees for important resources such as space, light, nutrients, or water.

Overall, the study highlights the importance of native tree diversity in helping to limit the severity of these invasions. “We found that native biodiversity can limit the severity or intensity of non-native tree species invasions worldwide,” says Camille Delavaux, lead author of the study. “This means that the extent of invasion can be mitigated by promoting greater native tree diversity.”

The findings have direct relevance for efforts to manage ecosystems in the fight against biodiversity loss across the globe. “By identifying regions that are most vulnerable to invasion, this analysis is useful for designing effective strategies to protect global biodiversity,” says ETH Zurich professor Thomas Crowther.

The findings are significant for biodiversity conservation efforts worldwide. One key goal of the global biodiversity framework adopted at COP 15 in Montreal in 2022 is to prevent the establishment and spread of potentially invasive species. This global analysis of non-native tree species aims to contribute to the findings of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), which is expected to highlight the substantial impact of invasive species on biodiversity loss in their upcoming status report.

“This global understanding of non-native tree distributions can help countries to prioritize decision making in efforts to halt and reverse the loss of biodiversity,” Crowther emphasizes.

Source: ETH Zurich

A new study identifies a potential way to remove microplastics from water with fungi.

“Although fungal pelletization has been studied for algae harvesting and wastewater treatment in the past decade, to the best of our knowledge, it has not yet been applied for the removal of microplastics from an aqueous environment,” says Susie Dai, an associate professor in the plant pathology and microbiology department at Texas A&M University. “This study examines their use for that purpose.”

Microplastics, tiny plastic particles resulting from commercial product development and the breakdown of larger plastics, have gained increasing attention in recent years due to their potential harm to the ecosystem. With the continual increase of global plastic production, pollution from this persistent waste contaminant group derived from synthetic polymers presents a significant environmental challenge.

While the health risks posed by submicrometer microplastics to humans are not yet fully understood, those studying them generally believe the overall risk associated with submicrometer microplastics—those less than a micron in a specified measurement—is higher than that of larger plastics. They hypothesize this is due in large measure to their greater potential for long-range transport and ability to more easily penetrate the cells of living organisms.

“Previous studies have indicated that submicrometer microplastics can easily travel considerable distances in the environment, infiltrating plant root cell walls,” says study leader and postdoctoral scientist Huaimin Wang. “They have even been shown to have been transported into plant fruiting bodies and human placenta.”

Besides microplastics generated from direct human activity such as cosmetic and industrial production, nanoplastics—synthetic polymer particulates ranging from 1 nanometer to 1 micrometer in diameter—can also be generated from the fragmentation or degradation of larger plastics.

A significant portion of microplastics generated from human activities end up in sewage and wastewater treatment plants. While these plants can remove the vast majority of them, many of the submicrometer particles are unfiltered.

“The microplastics and nanoplastics removed after activated sludge treatment can be further removed by additional conventional methods such as coagulation, disk filters, and membrane filtration,” Dai says. “But enriched microplastics still pose a waste-management challenge.”

Unfortunately, she says, some disposal methods like landfill interment or incineration are not environmentally favorable for reintroducing these back into the natural carbon cycle.

For the study, three fungal strain candidates were chosen based on their speed of growth, dye degradation, spore production, and pellet formation. Two were newly isolated white rot fungi strains.

The study yielded encouraging findings on removing polystyrene and polymethyl methacrylate microplastics and nanoplastics—ranging from 200 nanometers to 5 micrometers in the aquatic environment—using these isolated fungal strains.

“These types of microplastics and nanoplastics are among the most common,” Dai says.

The three strains showed a high rate of microplastic removal and exhibited potential microplastic assimilation. “The microplastics attach to the surface of the fungal biomass, which makes it easier to remove them from water as part of the pellet,” Dai explains.

Wang says that due to the unique capacity of the selected white rot fungal strains to form pellets, they should be suitable for remediating microplastics. “They may also have the potential for use in upgrading wastewater treatment plants and as a cost-effective means to further remove microplastics and minimize the pollution by plastics in natural water bodies,” he says.

The current study using fungus to remove microplastics is compatible with Dai’s previous research using fungus to remediate PFAS or “forever chemicals” in the environment.

“Fungi have unique environmental applications due to their diversity and robustness,” Dai says. “They have also been useful in our ability to develop a novel bioremediation technology for these chemicals, which can threaten human health and ecosystem sustainability.”

PFAS are used in many applications ranging from food wrappers and packaging, to dental floss, fire-fighting foam, nonstick cookware, textiles, and electronics.

Dai’s new technology uses a plant-derived material to absorb the PFAS and dispose of them by means of microbial fungi that literally eat them.

The United States Department of Agriculture Forest Service’s Northern Research Station also participated in the study, which appears in Bioresource Technology Reports.

Source: Texas A&M University