Semua Kabar

UNIVERSITY PARK, Pa. — Silicon is king in the semiconductor technology that underpins smartphones, computers, electric vehicles and more, but its crown may be slipping according to a team led by researchers at Penn State. In a world first, they used two-dimensional (2D) materials, which are only an atom thick and retain their properties at that scale, unlike silicon, to develop a computer capable of simple operations.

The development, published today (June 11) inNature, represents a major leap toward the realization of thinner, faster and more energy-efficient electronics, the researchers said. They created a complementary metal-oxide semiconductor (CMOS) computer — technology at the heart of nearly every modern electronic device — without relying on silicon. Instead, they used two different 2D materials to develop both types of transistors needed to control the electric current flow in CMOS computers: molybdenum disulfide for n-type transistors and tungsten diselenide for p-type transistors.

“Silicon has driven remarkable advances in electronics for decades by enabling continuous miniaturization of field-effect transistors (FETs),” saidSaptarshi Das, the Ackley Professor of Engineering and professor of engineering science and mechanics at Penn State, who led the research. FETs control current flow using an electric field, which is produced when a voltage is applied. “However, as silicon devices shrink, their performance begins to degrade. Two-dimensional materials, by contrast, maintain their exceptional electronic properties at atomic thickness, offering a promising path forward.”

Das explained that CMOS technology requires both n-type and p-type semiconductors working together to achieve high performance at low power consumption — a key challenge that has stymied efforts to move beyond silicon. Although previous studies demonstrated small circuits based on 2D materials, scaling to complex, functional computers had remained elusive, Das said.

“That’s the key advancement of our work,” Das said. “We have demonstrated, for the first time, a CMOS computer built entirely from 2D materials, combining large area grown molybdenum disulfide and tungsten diselenide transistors.”

The team used metal-organic chemical vapor deposition (MOCVD) — a fabrication process that involves vaporizing ingredients, forcing a chemical reaction and depositing the products onto a substrate — to grow large sheets of molybdenum disulfide and tungsten diselenide and fabricate over 1,000 of each type of transistor. By carefully tuning the device fabrication and post-processing steps, they were able to adjust the threshold voltages of both n- and p-type transistors, enabling the construction of fully functional CMOS logic circuits.

“Our 2D CMOS computer operates at low-supply voltages with minimal power consumption and can perform simple logic operations at frequencies up to 25 kilohertz,” said first author Subir Ghosh, a doctoral student pursuing a degree in engineering science and mechanics under Das’s mentorship.

Ghosh noted that the operating frequency is low compared to conventional silicon CMOS circuits, but their computer — known as a one instruction set computer — can still perform simple logic operations.

“We also developed a computational model, calibrated using experimental data and incorporating variations between devices, to project the performance of our 2D CMOS computer and benchmark it against state-of-the-art silicon technology,” Ghosh said. “Although there remains scope for further optimization, this work marks a significant milestone in harnessing 2D materials to advance the field of electronics.”

Das agreed, explaining that more work is needed to further develop the 2D CMOS computer approach for broad use, but also emphasizing that the field is moving quickly when compared to the development of silicon technology.

“Silicon technology has been under development for about 80 years, but research into 2D materials is relatively recent, only really arising around 2010,” Das said. “We expect that the development of 2D material computers is going to be a gradual process, too, but this is a leap forward compared to the trajectory of silicon.”

Ghosh and Das credited the2D Crystal Consortium Materials Innovation Platform(2DCC-MIP) at Penn State with providing the facilities and tools needed to demonstrate their approach. Das is also affiliated with theMaterials Research Institute, the 2DCC-MIP and the Departments of Electrical Engineering and of Materials Science and Engineering, all at Penn State. Other contributors from the Penn State Department of Engineering Science and Mechanics include graduate students Yikai Zheng, Najam U. Sakib, Harikrishnan Ravichandran, Yongwen Sun, Andrew L. Pannone, Muhtasim Ul Karim Sadaf and Samriddha Ray; and Yang Yang, assistant professor. Yang is also affiliated with the Materials Research Institute and the Ken and Mary Alice Lindquist Department of Nuclear Engineering at Penn State. Joan Redwing, director of the 2DCC-MIP and distinguished professor of materials science and engineering and of electrical engineering, and Chen Chen, assistant research professor, also co-authored the paper. Other contributors include Musaib Rafiq and Subham Sahay, Indian Institute of Technology; and Mrinmoy Goswami, Jadavpur University.

The U.S. National Science Foundation, the Army Research Office and the Office of Naval Research supported this work in part.

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A group of bat viruses closely related to the deadly Middle East respiratory syndrome coronavirus (MERS-CoV) could be one small mutation away from being capable of spilling over into human populations and potentially causing the next pandemic.

A recent study published in the journalNature Communicationsexamined an understudied group of coronaviruses known as merbecoviruses — the same viral subgenus that includes MERS-CoV — to better understand how they infect host cells. The research team, which included scientists at Washington State University, the California Institute of Technology and the University of North Carolina, found that while most merbecoviruses appear unlikely to pose a direct threat to people, one subgroup known as HKU5 possesses concerning traits.

"Merbecoviruses – and HKU5 viruses in particular – really hadn't been looked at much, but our study shows how these viruses infect cells," said Michael Letko, a virologist at WSU's College of Veterinary Medicine who helped to spearhead the study. "What we also found is HKU5 viruses may be only a small step away from being able to spill over into humans."

During the past two decades, scientists have cataloged the genetic sequences of thousands of viruses in wild animals, but, in most cases, little is known about whether these viruses pose a threat to humans. Letko's lab in WSU's Paul G. Allen School for Global Health focuses on closing that gap and identifying potentially dangerous viruses.

For their most recent study, Letko's team targeted merbecoviruses, which have received limited attention apart from MERS-CoV, a zoonotic coronavirus first noted in 2012 that is transmitted from dromedary camels to humans. It causes severe respiratory disease and has a mortality rate of approximately 34%.

Like other coronaviruses, merbecovirusesrely on a spike protein to bind to receptors and invade host cells. Letko's team used virus-like particles containing only the portion of the spike responsible for binding to receptors and tested their ability to infect cells in the lab. While most merbecoviruses appear unlikely to be able to infect humans, HKU5 viruses – which have been found across Asia, Europe, Africa and the Middle East – were shown to use a host receptor known as ACE2, the same used by the more well-known SARS-CoV-2 virus that causes COVID-19. One small difference: HKU5 viruses, for now, can only use the ACE2 gene in bats, but do not use the human version nearly as well.

Examining HKU5 viruses found in Asia where their natural host is the Japanese house bat (Pipistrellus abramus), the researchers demonstrated some mutations in the spike protein that may allow the viruses to bind to ACE2 receptors in other species, including humans. Researchers on another study that came out earlier this year analyzed one HKU5 virus in China that has already been documented to have jumped into minks, showing there is potential for these viruses to cross species-barriers.

"These viruses are so closely related to MERS, so we have to be concerned if they ever infect humans," Letko said. "While there's no evidence they've crossed into people yet, the potential is there — and that makes them worth watching."

The team also used artificial intelligence to explore the viruses. WSU postdoctoral researcher Victoria Jefferson used a program called AlphaFold 3 to model how the HKU5 spike protein binds to ACE2 at the molecular level, which could help provide a better understanding of how antibodies might block the infection or how the virus could mutate.

Up until this point, such structural analysis required months of lab work and specialized equipment. With AlphaFold, Jefferson generated accurate predictions in minutes. The results matched those recently documented by a research team that used traditional approaches.

Letko noted the study and its methods could be used for future research projects and aid in the development of new vaccines and treatments.

The research was funded through a research project grant from the National Institutes of Health. Jefferson's work was supported by an NIH T32 training grant.

Materialsprovided byWashington State University.Note: Content may be edited for style and length.

Researchers at the University of California, Davis, have developed an investigational brain-computer interface that holds promise for restoring the voices of people who have lost the ability to speak due to neurological conditions.

In a new study published in the scientific journalNature,the researchers demonstrate how this new technology can instantaneously translate brain activity into voice as a person tries to speak — effectively creating a digital vocal tract.

The system allowed the study participant, who has amyotrophic lateral sclerosis (ALS), to "speak" through a computer with his family in real time, change his intonation and "sing" simple melodies.

"Translating neural activity into text, which is how our previous speech brain-computer interface works, is akin to text messaging. It's a big improvement compared to standard assistive technologies, but it still leads to delayed conversation. By comparison, this new real-time voice synthesis is more like a voice call," said Sergey Stavisky, senior author of the paper and an assistant professor in the UC Davis Department of Neurological Surgery. Stavisky co-directs the UC Davis Neuroprosthetics Lab.

"With instantaneous voice synthesis, neuroprosthesis users will be able to be more included in a conversation. For example, they can interrupt, and people are less likely to interrupt them accidentally," Stavisky said.

Decoding brain signals at heart of new technology

The man is enrolled in the BrainGate2 clinical trial at UC Davis Health. His ability to communicate through a computer has been made possible with an investigational brain-computer interface (BCI). It consists of four microelectrode arrays surgically implanted into the region of the brain responsible for producing speech.

These devices record the activity of neurons in the brain and send it to computers that interpret the signals to reconstruct voice.

"The main barrier to synthesizing voice in real-time was not knowing exactly when and how the person with speech loss is trying to speak," said Maitreyee Wairagkar, first author of the study and project scientist in the Neuroprosthetics Lab at UC Davis. "Our algorithms map neural activity to intended sounds at each moment of time. This makes it possible to synthesize nuances in speech and give the participant control over the cadence of his BCI-voice."

Instantaneous, expressive speech with BCI shows promise

The brain-computer interface was able to translate the study participant's neural signals into audible speech played through a speaker very quickly — one-fortieth of a second. This short delay is similar to the delay a person experiences when they speak and hear the sound of their own voice.

The technology also allowed the participant to say new words (words not already known to the system) and to make interjections. He was able to modulate the intonation of his generated computer voice to ask a question or emphasize specific words in a sentence.

The participant also took steps toward varying pitch by singing simple, short melodies.

His BCI-synthesized voice was often intelligible: Listeners could understand almost 60% of the synthesized words correctly (as opposed to 4% when he was not using the BCI).

Real-time speech helped by algorithms

The process of instantaneously translating brain activity into synthesized speech is helped by advanced artificial intelligence algorithms.

The algorithms for the new system were trained with data collected while the participant was asked to try to speak sentences shown to him on a computer screen. This gave the researchers information about what he was trying to say.

The neural activity showed the firing patterns of hundreds of neurons. The researchers aligned those patterns with the speech sounds the participant was trying to produce at that moment in time. This helped the algorithm learn to accurately reconstruct the participant's voice from just his neural signals.

"Our voice is part of what makes us who we are. Losing the ability to speak is devastating for people living with neurological conditions," said David Brandman, co-director of the UC Davis Neuroprosthetics Lab and the neurosurgeon who performed the participant's implant.

"The results of this research provide hope for people who want to talk but can't. We showed how a paralyzed man was empowered to speak with a synthesized version of his voice. This kind of technology could be transformative for people living with paralysis."

Brandman is an assistant professor in the Department of Neurological Surgery and is the site-responsible principal investigator of the BrainGate2 clinical trial.

The researchers note that although the findings are promising, brain-to-voice neuroprostheses remain in an early phase. A key limitation is that the research was performed with a single participant with ALS. It will be crucial to replicate these results with more participants, including those who have speech loss from other causes, such as stroke.

The BrainGate2 trial is enrolling participants. To learn more about the study, visitbraingate.orgor contact[email protected].

Caution: Investigational device, limited by federal law to investigational use.

Materialsprovided byUniversity of California – Davis Health.Note: Content may be edited for style and length.

Weight loss drugs like Ozempic and Wegovy are used by over 15 million adults in the U.S., or 4.5% of the population. Despite their effectiveness, they have drawbacks. Their effect may not last after discontinuing use, and side effects including osteoporosis and muscle loss have raised concerns about long-term harms. They also induce nausea, which can make it difficult to stay the course of treatment.

Now Tufts researchers led by Krishna Kumar, Robinson Professor of Chemistry, have designed a new, next-generation compound with hopes that it could be more effective with fewer side effects, which they report in a paper in theJournal of the American Chemical Society.

While weight loss drugs currently on the market and in development target one, two, or even three hormone receptors related to glucose metabolism and the desire to eat, the Tufts team has identified a fourth target that could potentially further enhance the control strategy.

"Obesity is linked to over 180 different disease conditions, including cancer, cardiovascular disease, osteoarthritis, liver disease, and type 2 diabetes, and affects over 650 million people worldwide," said Kumar. "What drives us is the idea that we can design a single drug to treat obesity and simultaneously mitigate the risk of developing a long list of health problems plaguing society."

After we eat a meal, our gut and brain trigger a hormonal "fuel gauge" that regulates levels of glucose and tells us when we have had enough to eat.

The hormone glucagon-like peptide 1 (GLP-1) is released to help stimulate the production of insulin and the uptake of glucose in muscle and other tissues. With the cells now loaded with fuel, the level of glucose in the blood returns to normal. Ozempic uses GLP-1 with slight modifications to increase its availability in the bloodstream. Its success in controlling blood glucose has prompted the American Diabetes Association to recommend it and other GLP-1-based drugs as the new first line injectable treatments for diabetes, ahead of insulin.

But GLP-1 also acts directly on the brain, making us feel full after having a meal, and it slows down the rate that the stomach contents are emptied into the intestines, creating a more evenly paced release of nutrients and glucose into the bloodstream. That's why it has also become extremely popular as a weight loss treatment.

It's still not a perfect drug strategy for weight loss, though. "The biggest problem with GLP-1 drugs is that they have to be injected once a week, and they can induce a very strong feeling of nausea," said Kumar. "As much as 40% of people using these drugs give up after the first month."

A second hormone released after eating is glucose-dependent insulinotropic peptide (GIP). It also makes us feel full after a meal. GIP looks a lot like GLP-1, so rather than administer two drugs, researchers created one peptide that incorporates structural elements of both — what's called in drug development a chimera. That drug, called Mounjaro or Zepbound (the brand names for tirzepatide), has the added benefit of significantly reducing nausea. As a more tolerable treatment, it may overtake Ozempic in the weight loss market.

"And then there is a third hormone, glucagon," said Kumar. "Paradoxically, it actually increases blood glucose, but at the same time increases the expenditure of energy in cells of the body, raises body temperature, and suppresses appetite." By adding glucagon to the mix, GLP-1 and GIP end up neutralizing its glucose-enhancing effect, leaving the remaining functionalities of all three hormones working together to enhance weight loss.

Glucagon is also similar in structure to GLP-1 and GIP, so drug developers created a single chimera peptide that incorporates elements of all three hormones, which can be recognized by their three separate receptors. That drug, called retatrudide, is currently in clinical trials that indicate even greater achievable weight loss (up to 24%) compared to the original GLP-1 drugs (6-15%).

Going for the Weight Loss Gold Standard with a Fourth Target

"The goal that people are trying to shoot for is bariatric surgery," said Kumar. That's a surgical procedure significantly reducing the size of the stomach, which can achieve long-lasting weight loss up to 30%. "For individuals with persistent obesity and potential deadly associated conditions, it becomes a necessary but invasive treatment."

Current injectable weight loss drugs still fall short of that gold standard, so the Tufts chemists are focused on a drug redesign that could match the 30% weight loss outcome.

"There is one more hormone we wanted to bring in to complete a weight control quartet," said Tristan Dinsmore, a graduate student in the Kumar lab and the lead author of the study. "It's called peptide YY (PYY). This molecule is also secreted by the gut after we eat a meal, and its job is to reduce appetite and slow the process of emptying food from the stomach, but via different mechanisms than either GLP-1 or GIP. It may also be involved in directly 'burning off' fat."

PYY is from a separate and structurally unrelated class of hormones than the first three, so blending its structure into a chimeric peptide that also mimics GLP-1, GIP, and glucagon was not easy. Instead, the Tufts team was able to join two peptide segments end-to-end, creating a new 'tetra-functional' clinical candidate.

"One of the limitations of the current drugs is that individual variation, possibly including how people express target receptors or respond to their corresponding hormones, can lead to lesser than desired weight loss outcomes in many patients," said Martin Beinborn, visiting scholar in the Department of Chemistry. "By hitting four different hormone receptors at the same time, we hope to improve the chances of averaging out such variation toward the goal of achieving greater and more consistent overall effectiveness."

"A second issue is that patients tend to regain weight after discontinuing currently available GLP-1 related drugs," said Beinborn, who notes that lifestyle changes should ideally be a complement to medication treatment. This two-pronged approach will not only support reaching and keeping one's target weight, but may also help preserve bone and muscle mass.

"Recent studies indicate that weight rebound after drug discontinuation is delayed with the newer, more effective GLP-1 mimetics," he said. "Extending from this observation, one may speculate that multi-chimeras along the lines of the one we discovered could get us closer to the bariatric surgery standard of lasting weight loss."

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Astronomers have surveyed massive, dense star factories, unlike any found in the Milky Way, in a large number of galaxies across the local universe. The findings provide a rare glimpse into processes shaping galaxies in the very early universe and possibly the Milky Way a few billion years from now.

Known as luminous and ultra-luminous infrared galaxies, or LIRGs and ULIRGs, these galaxies are relatively rare in the local universe, with only 202 known within 400 megaparsecs (1.3 billion light-years) from Earth, according to Sean Linden, a research associate at the University of Arizona Steward Observatory, who presented the findings during a press briefing at the 246th meeting of the American Astronomical Society on June 11.

LIRGs and ULIRGs differ from spiral galaxies like the Milky Way in that they are in the process of merging with other galaxies. Most exhibit features such as two galactic nuclei instead of one or extended "tails" as gravity stretches and deforms the two objects. And unlike "modern" galaxies, they contain "clumps" – dense regions brimming with newborn stars, much more massive than anything found in "typical," evolved galaxies that are not undergoing mergers.

"These galaxies are very clumpy, very different from the beautiful spiral galaxies that we see now, such as the Milky Way," Linden said. "And we know from cosmological simulations that these clumps were the building blocks of galaxies in the early universe."

Astronomers are interested in LIRGs and ULIRGs because they serve as windows into a distant past when the universe was much younger and galaxies were much less evolved and crashed into each other much more frequently than today.

This is where the Great Observatories All-sky LIRG Survey comes in, or GOALS for short. It combines imaging and spectroscopic data from NASA's Spitzer, Hubble, Chandra and GALEX spaceborne observatories in a comprehensive study of more than 200 of the most luminous infrared-selected galaxies in the local universe. Now, infrared observations with NASA's James Webb Space Telescope have provided the most complete census of these galaxies. Running from October 2023 until September 2024, the survey is the only of its kind. The team plans to publish the results in a forthcoming issue of The Astrophysical Journal.

"You can imagine a million suns forming in one small, compact region, and within one of those galaxies, there are hundreds of thousands of such clumps," Linden said.

For comparison, the most massive young clumps in the Milky Way have masses of about 1,000 suns and, on average, one star is born each year.

When two galaxies collide and merge, star formation rates increase dramatically, Linden explained, resulting in the massive clumps that are not seen in other galaxies that are not undergoing mergers.

"These clumpy structures build up over time until they become incredibly massive, and if we want to understand them and how they actually contribute to galaxies evolving throughout cosmic time, we need to study them in detail," Linden said.

Although star-forming clumps had already been observed with the Hubble Space Telescope, only the infrared capabilities of JWST allowed astronomers to pull aside the veils of thick dust that had prevented them from obtaining a more detailed look at these features.

The survey results also confirm predictions of galaxy evolution based on simulations done by supercomputers, which predicted that "typical," disk-like galaxies contain fewer clumps of star formation, and most of the star formation happens in small clumps, as seen in the Milky Way today. Mergers produce bigger clumps, and more of them, and more of the star formation takes place in the massive clumps.

"We're now finding these massive clumps in the local universe," Linden said. "We are beginning to complete the picture by comparing for the first time observations of massive clumps from both the nearby and the distant universe."

Being able to discern previously hidden details in these unusually massive star-forming clumps helps researchers better understand how these features and their host galaxies evolved over time, essentially providing a natural laboratory for a type of galaxy that for the most part no longer exists in the universe except for its most distant, outer regions.

"In a sense, you look at the local universe, and it gives you information about what would have happened 10 billion years ago," said Linden, whose work focused on imaging the clumps and the star clusters, and who led the data acquisition, reduction and analysis.

The early universe was much denser, he explained, and mergers between galaxies happened much more frequently, producing massive star-forming clumps. As the universe evolved and space expanded, the galaxies became more and more like the Milky Way and the mature spiral galaxies we see today.

"The universe used to be much more violent and extreme in the past, and it's now settling down," Linden said. "That's why these rare examples of extreme galaxies no longer exist in the local universe, because, by and large, most galaxies have settled down as well."

In addition to providing windows into the past, the surveyed galaxies also hint at the future, Linden said. At some point, the Milky Way and Andromeda galaxies are going to collide, over the course of several billions of years, and when that happens, the merger could ignite another round of massive star formation in both galaxies.

"As Andromeda gets closer and the pressure in the interstellar medium goes up, all of a sudden, the clumps that you will find that the Milky Way is forming will be more and more massive."

Materialsprovided byUniversity of Arizona.Note: Content may be edited for style and length.

A new study has revealed for the first time that ancient carbon, stored in landscapes for thousands of years or more, can find its way back to the atmosphere as CO2 released from the surfaces of rivers.

The findings, led by scientists at the University of Bristol and the cover story of the journalNature,mean plants and shallow soil layers are likely removing around one gigatonne more CO2 each year from the atmosphere to counteract this, emphasising their pivotal and greater part in combating climate change.

Lead author Dr Josh Dean, Associate Professor in Biogeochemistry and UKRI Future Leaders Fellow at the University of Bristol, said: "The results took us by surprise because it turns out that old carbon stores are leaking out much more into the atmosphere then previous estimates suggested.

"The implications are potentially huge for our understanding of global carbon emissions. Plants and trees take up CO2from the atmosphere and can then lock this carbon away in soils for thousands of years.

"Our findings show some of this old carbon, as well as ancient carbon from rocks, is leaking sideways into rivers and making its way back to the atmosphere. We don't yet know how humans are affecting this flow of ancient carbon, but we do know plants and trees must be taking up more carbon from the atmosphere today to account for this unrecognised release of old carbon."

Rivers transport and release methane and carbon dioxide as part of the global carbon cycle. Until now, scientists believed the majority of this was a quick turnover derived from the recycling of recent plant growth – organic material broken down and carried into the river system in the past 70 years or so. This new study indicates the opposite, with more than half – some 60% – of emissions being attributed to long-term carbon stores accumulated over hundreds to thousands of years ago, or even longer.

The international research team, led by scientists at the University of Bristol, University of Oxford and the UK Centre for Ecology and Hydrology, studied more than 700 river reaches from 26 different countries across the world.

They took detailed radiocarbon measurements of carbon dioxide and methane from the rivers. By comparing the levels of carbon-14 in the river samples with a standard reference for modern atmospheric CO2, the team was able to date the river carbon.

Co-author Prof Bob Hilton, Professor of Sedimentary Geography at the University of Oxford, explained: "We discovered that around half of the emissions are young, while the other half are much older, released from deep soil layers and rock weathering that were formed thousands and even millions of years ago."

The research was supported by funding from UK Research and Innovation (UKRI) Natural Environment Research Council (NERC).

Co-author Dr Gemma Coxon, Associate Professor in Hydrology and UKRI Future Leaders Fellow at the University of Bristol, said: "Rivers globally release about two gigatonnes of carbon each year, compared to human activity that results in between 10-15 gigatonnes of carbon emissions. These river emissions are significant at a global scale, and we're showing that over half of these emissions may be coming from carbon stores we considered relatively stable. This means we need to re-evaluate these crucial parts of the global carbon cycle."

Further building on these findings, the researchers plan to explore how the age of river carbon emissions varies across rivers the study was not able to capture, as well as investigating how the age of these emissions may have changed through time.

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Researchers at Johannes Gutenberg University Mainz (JGU), the Max Planck Institute for Polymer Research and the University of Texas at Austin have identified a form of molecular motion that has not previously been observed. When what are known as 'guest molecules' – molecules that are accommodated within a host molecule – penetrate droplets of DNA polymers, they do not simply diffuse in them in a haphazard fashion, but propagate through them in the form of a clearly-defined frontal wave. "This is an effect we did not expect at all," points out Weixiang Chen of the Department of Chemistry at JGU, who played a major role in the discovery. The findings of the research team have today been published in an article in the prestigious journalNature Nanotechnology. The new insights are not only fundamental to our understanding of how cells regulate signals, but they could also contribute to the development of intelligent biomaterials, innovative types of membranes, programmable carriers of active ingredients and synthetic cell systems able to imitate the organizational complexity of the processes in living beings. Molecular wave patterns instead of conventional diffusion

It is usually the case that molecules are distributed throughout liquids by means of simple diffusion. For instance, if you add a blue dye to a glass of water, the dye gradually disperses in the liquid, forming soft, blurry color gradients. However, the observed behavior of guest molecules in DNA droplets is quite different. "The molecules move in a structured and controlled manner that is contrary to the traditional models, and this takes the form of what appears to be a wave of molecules or a mobile boundary," explains Professor Andreas Walther from JGU's Department of Chemistry, who led the research project.

The research team used droplets made up of thousands of individual strands of DNA, structures that are also known as biomolecular condensates. What is of particular interest in this connection is the fact that the properties of the droplets can be precisely determined with the help of the DNA structures and other parameters, such as the concentration of salts. Moreover, these droplets have their counterparts in biological cells, which are able to employ similar condensates to arrange complex biochemical processes without the need for membranes. "Our synthetic droplets thus represent an excellent model system with which we can simulate natural processes and come to better understand them," emphasizes Chen. Into their droplets, the researchers introduced specially designed 'guest' DNA strands that are able to specifically recognize the inner structure of the droplets and bind to them. According to the team, the intriguing motion of the guest molecules, that they have now detected for the first time, is in part attributable to the way that the added DNA and the DNA present in the droplets combine on the basis of the key-and-lock principle. This means that the surrounding material becomes less dense and no longer fixed in place, so that swollen, dynamic states develop locally. Chen adds: "The well-defined, highly concentrated front continues to move forward in a linear fashion over time, driven by chemical binding, material conversion and programmable DNA interactions. Something that is completely new when it comes to soft matter."

New basis for understanding cellular processes

The findings are not only relevant to providing us with a better understanding of the physics of soft matter, but also to improving our knowledge of the chemical processes that occur in cells. "This might be one of the missing pieces of the puzzle that, once assembled, will reveal to us how cells regulate signals and organize processes on the molecular level," states Walther. This would also be of interest when it comes to the treatment of neurodegenerative disorders in which proteins migrate from cell nuclei into the cytoplasm, forming condensates there. As these age, they transform from a dynamic to a more stable state and build the problematic fibrils. "It is quite conceivable that we may be able to find a way of influencing these aging processes with the aid of our new insights, so that, over the long term, an entirely new approach to the treatment of neurodegenerative diseases could emerge," concludes Walther.

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The accumulation of microplastics in the environment, and within our bodies, is an increasingly worrisome issue. But predicting where these ubiquitous particles will accumulate, and therefore where remediation efforts should be focused, has been difficult because of the many factors that contribute to their dispersal and deposition.

New research from MIT shows that one key factor in determining where microparticles are likely to build up has to do with the presence of biofilms. These thin, sticky biopolymer layers are shed by microorganisms and can accumulate on surfaces, including along sandy riverbeds or seashores. The study found that, all other conditions being equal, microparticles are less likely to accumulate in sediment infused with biofilms, because if they land there, they are more likely to be resuspended by flowing water and carried away.

The open-access findings appear in the journalGeophysical Research Letters, in a paper by MIT postdoc Hyoungchul Park and professor of civil and environmental engineering Heidi Nepf. "Microplastics are definitely in the news a lot," Nepf says, "and we don't fully understand where the hotspots of accumulation are likely to be. This work gives a little bit of guidance" on some of the factors that can cause these particles, and small particles in general, to accumulate in certain locations.

Most experiments looking at the ways microparticles are transported and deposited have been conducted over bare sand, Park says. "But in nature, there are a lot of microorganisms, such as bacteria, fungi, and algae, and when they adhere to the stream bed they generate some sticky things." These substances are known as extracellular polymeric substances, or EPS, and they "can significantly affect the channel bed characteristics," he says. The new research focused on determining exactly how these substances affected the transport of microparticles, including microplastics.

The research involved a flow tank with a bottom lined with fine sand, and sometimes with vertical plastic tubes simulating the presence of mangrove roots. In some experiments the bed consisted of pure sand, and in others the sand was mixed with a biological material to simulate the natural biofilms found in many riverbed and seashore environments.

Water mixed with tiny plastic particles was pumped through the tank for three hours, and then the bed surface was photographed under ultraviolet light that caused the plastic particles to fluoresce, allowing a quantitative measurement of their concentration.

The results revealed two different phenomena that affected how much of the plastic accumulated on the different surfaces. Immediately around the rods that stood in for above-ground roots, turbulence prevented particle deposition. In addition, as the amount of simulated biofilms in the sediment bed increased, the accumulation of particles also decreased.

Nepf and Park concluded that the biofilms filled up the spaces between the sand grains, leaving less room for the microparticles to fit in. The particles were more exposed because they penetrated less deeply in between the sand grains, and as a result they were much more easily resuspended and carried away by the flowing water.

"These biological films fill the pore spaces between the sediment grains," Park explains, "and that makes the deposited particles — the particles that land on the bed — more exposed to the forces generated by the flow, which makes it easier for them to be resuspended. What we found was that in a channel with the same flow conditions and the same vegetation and the same sand bed, if one is without EPS and one is with EPS, then the one without EPS has a much higher deposition rate than the one with EPS."

Nepf adds: "The biofilm is blocking the plastics from accumulating in the bed because they can't go deep into the bed. They just stay right on the surface, and then they get picked up and moved elsewhere. So, if I spilled a large amount of microplastic in two rivers, and one had a sandy or gravel bottom, and one was muddier with more biofilm, I would expect more of the microplastics to be retained in the sandy or gravelly river."

All of this is complicated by other factors, such as the turbulence of the water or the roughness of the bottom surface, she says. But it provides a "nice lens" to provide some suggestions for people who are trying to study the impacts of microplastics in the field. "They're trying to determine what kinds of habitats these plastics are in, and this gives a framework for how you might categorize those habitats," she says. "It gives guidance to where you should go to find more plastics versus less."

As an example, Park suggests, in mangrove ecosystems, microplastics may preferentially accumulate in the outer edges, which tend to be sandy, while the interior zones have sediment with more biofilm. Thus, this work suggests "the sandy outer regions may be potential hotspots for microplastic accumulation," he says, and can make this a priority zone for monitoring and protection.

The work was supported by Shell International Exploration and Production through the MIT Energy Initiative.

Materialsprovided byMassachusetts Institute of Technology. Original written by David L. Chandler.Note: Content may be edited for style and length.

Using advanced single-nuclei RNA sequencing (snRNA-seq) and a widely used preclinical model for Alzheimer's disease, researchers from Mass General Brigham and collaborators at SUNY Upstate Medical University have identified specific brain cell types that responded most to exercise. These findings, which were validated in samples from people, shed light on the connection between exercise and brain health and point to future drug targets. Results are published inNature Neuroscience.

"While we've long known that exercise helps protect the brain, we didn't fully understand which cells were responsible or how it worked at a molecular level," said senior author Christiane D. Wrann, DVM, PhD, a neuroscientist and leader of the Program in Neuroprotection in Exercise at the Mass General Brigham Heart and Vascular Institute and the McCance Center for Brain Health at Massachusetts General Hospital. "Now, we have a detailed map of how exercise impacts each major cell type in the memory center of the brain in Alzheimer's disease."

The study focused on a part of the hippocampus — a critical region for memory and learning that is damaged early in Alzheimer's disease. The research team leveraged single-nuclei RNA sequencing, a relatively new technologies that allow researchers to look at activity at the molecular level in single cells for an in-depth understanding of diseases like Alzheimer's.

The researchers exercised a common mouse model for Alzheimer's disease using running wheels, which improved their memory compared to the sedentary counterparts. They then analyzed gene activity across thousands of individual brain cells, finding that exercise changed activity both in microglia, a disease-associated population of brain cells, and in a specific type of neurovascular-associated astrocyte (NVA), newly discovered by the team, which are cells associated with blood vessels in the brain. Furthermore, the scientist identified the metabolic gene Atpif1 as an important regulator to create new neurons in the brain. "That we were able to modulate newborn neurons using our new target genes set underscores the promise our study," said lead author Joana Da Rocha, PhD, a postdoctoral fellow working in Dr. Wrann's lab.

To ensure the findings were relevant to humans, the team validated their discoveries in a large dataset of human Alzheimer's brain tissue, finding striking similarities.

"This work not only sheds light on how exercise benefits the brain but also uncovers potential cell-specific targets for future Alzheimer's therapies," said Nathan Tucker, a biostatistician at SUNY Upstate Medical University and co-senior of the study. "Our study offers a valuable resource for the scientific community investigating Alzheimer's prevention and treatment."

Authorship: In addition to da Rocha and Wrann, Mass General Brigham authors include Renhao Luo, Pius Schlachter, Luis Moreira, Mohamed Ariff Iqbal, Paula Kuhn, Sophia Valaris, Mohammad R. Islam, Gabriele M. Gassner, Sofia Mazuera, Kaela Healy, Sanjana Shastri, Nathaniel B. Hibbert, Kristen V. Moran-Figueroa, Erin B. Haley, Sema Aygar, and Ksenia V. Kastanenka. Additional authors include Michelle L. Lance, Robert S. Gardner, Ryan D. Pfeiffer, Logan Brase, Oscar Harari, Bruno A. Benitez, and Nathan R. Tucker.

Disclosures: Wrann is an academic co-founder and consultant for Aevum Therapeutics. Wrann has a financial interest in Aevum Therapeutics, a company developing drugs that harness the protective molecular mechanisms of exercise to treat neurodegenerative and neuromuscular disorders. Wrann's interests were reviewed and are managed by Massachusetts General Hospital and Mass General Brigham in accordance with their conflict of interest policies.

Funding: This study was funded in part by the National Institutes of Health (NS117694, AG062904, AG064580, AG072054, HL140187, AG066171, AG057777, AG072464, NS118146, NS127211), Cure Alzheimer's Fund, Alzheimer Association Research Grant, SPARC Award from the McCance Center for Brain Health, Hassenfeld Clinical Scholar Award, Claflin Distinguished Scholar Award, BIDMC 2023 Translational Research Hub Spark Grant Award, Massachusetts General Hospital Fund for Medical Discovery (2024A022508), ADDF-Harrington

Materialsprovided byMass General Brigham.Note: Content may be edited for style and length.

Genetic material shed by tumors can be detected in the bloodstream three years prior to cancer diagnosis, according to a study led by investigators at the Ludwig Center at Johns Hopkins, Johns Hopkins Kimmel Cancer Center, the Johns Hopkins University School of Medicine and the Johns Hopkins Bloomberg School of Public Health.

The study, partly funded by the National Institutes of Health, was published May 22 inCancer Discovery.

Investigators were surprised they could detect cancer-derived mutations in the blood so much earlier, says lead study author Yuxuan Wang, M.D., Ph.D., an assistant professor of oncology at the Johns Hopkins University School of Medicine. "Three years earlier provides time for intervention. The tumors are likely to be much less advanced and more likely to be curable."

To determine how early cancers could be detected prior to clinical signs or symptoms, Wang and colleagues assessed plasma samples that were collected for the Atherosclerosis Risk in Communities (ARIC) study, a large National Institutes of Health-funded study to investigate risk factors for heart attack, stroke, heart failure and other cardiovascular diseases. They used highly accurate and sensitive sequencing techniques to analyze blood samples from 26 participants in the ARIC study who were diagnosed with cancer within six months after sample collection, and 26 from similar participants who were not diagnosed with cancer.

At the time of blood sample collection, eight of these 52 participants scored positively on a multicancer early detection (MCED) laboratory test. All eight were diagnosed within four months following blood collection. For six of the eight individuals, investigators also were able to assess additional blood samples collected 3.1-3.5 years prior to diagnosis, and in four of these cases, tumor-derived mutations could also be identified in samples taken at the earlier timepoint.

"This study shows the promise of MCED tests in detecting cancers very early, and sets the benchmark sensitivities required for their success," says Bert Vogelstein, M.D., Clayton Professor of Oncology, co-director of the Ludwig Center at Johns Hopkins and a senior author on the study.

"Detecting cancers years before their clinical diagnosis could help provide management with a more favorable outcome," adds Nickolas Papadopoulos, Ph.D., professor of oncology, Ludwig Center investigator and senior author of the study. "Of course, we need to determine the appropriate clinical follow-up after a positive test for such cancers."

The study was supported in part by National Institutes of Health grant #s R21NS113016, RA37CA230400, U01CA230691, P30 CA 06973, DRP 80057309, and U01 CA164975. Additional funding was provided by the Virginia and D.K. Ludwig Fund for Cancer Research, the Commonwealth Fund, the Thomas M Hohman Memorial Cancer Research Fund, The Sol Goldman Sequencing Facility at Johns Hopkins, The Conrad R. Hilton Foundation, the Benjamin Baker Endowment, Swim Across America, Burroughs Wellcome Career Award for Medical Scientists, Conquer Cancer — Fred J. Ansfield, MD, Endowed Young Investigator Award, and The V Foundation for Cancer Research. The Atherosclerosis Risk in Communities study has been funded in whole or in part with federal funds from the National Heart, Lung, and Blood Institute, National Institutes of Health, Department of Health and Human Services, under contract numbers 75N92022D00001, 75N92022D00002, 75N92022D00003, 75N92022D00004, and 75N92022D00005.

Materialsprovided byJohns Hopkins Medicine.Note: Content may be edited for style and length.