Aurelia Butler

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  • 138 Shares179 Views

    in Computers Math

    Intense lasers shine new light on the electron dynamics of liquids

    The behavior of electrons in liquids plays a big role in many chemical processes that are important for living things and the world in general. For example, slow electrons in liquid have the capacity to cause disruptions in the DNA strand.
    But electron movements are extremely hard to capture because they take place within attoseconds: the realm of quintillionths of a second. Since advanced lasers now operate at these timescales, they can offer scientists glimpses of these ultrafast processes via a range of techniques.
    An international team of researchers has now demonstrated that it is possible to probe electron dynamics in liquids using intense laser fields and to retrieve the electron’s mean free path — the average distance an electron can travel before colliding with another particle.
    “We found that the mechanism by which liquids emit a particular light spectrum, known as the high-harmonic spectrum, is markedly different from the ones in other phases of matter like gases and solids,” said Zhong Yin from Tohoku University’s International Center for Synchrotron Radiation Innovation Smart (SRIS) and co-first author of the paper. “Our findings open the door to a deeper understanding of ultrafast dynamics in liquids.”
    Details of the group’s research was published in the journal Nature Physics on September 28, 2023.
    Using intense laser fields to generate high-energy photons, a phenomenon known as high-harmonic generation (HHG), is a widespread technique used in many different areas of science, for instance for probing electronic motion in materials, or tracking chemical reactions in time. HHG has been studied extensively in gases and more recently in crystals, but much less is known about liquids.
    The research team, which also included researchers from the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg and ETH Zurich, reported on the unique behavior of liquids when irradiated by intense lasers. Until now, almost nothing is known about these light-induced processes in liquids, which surround us everywhere and are present in every chemical reaction. In contrast, scientists have made significant strides in recent years in exploring the behavior of solids under irradiation. Therefore, the experimental team at ETH Zurich developed a unique apparatus to specifically study the interaction of liquids with intense lasers. The researchers discovered a distinctive behavior where the maximum photon energy obtained through HHG in liquids was independent of the laser’s wavelength. What, then, was the responsible factor? More

  • 113 Shares139 Views

    in Computers Math

    Ball milling provides high pressure benefits to battery materials

    Cheaper, more efficient lithium-ion batteries could be produced by harnessing previously overlooked high pressures generated during the manufacturing process.
    Scientists at the University of Birmingham have discovered that routine ball milling can cause high pressure effects on battery materials in just a matter of minutes, providing a vital additional variable in the process of synthesizing battery materials.
    The research (part of the Faraday Institution funded CATMAT project), led by Dr Laura Driscoll, Dr Elizabeth Driscoll and Professor Peter Slater at the University of Birmingham is published in RSC Energy Environmental Science.
    The use of ball milling has been a huge area of growth in the lithium-ion battery space to make next generation materials. The process is simple and consists of milling powder compounds with small balls that mix and make the particles smaller, creating high-capacity electrode materials and leading to better performing batteries.
    Previous studies had led experts to believe that the synthesis of these materials was caused by localised heating generated in the milling process. But now researchers have found that dynamic impacts from the milling balls colliding with the battery materials create a pressure effect which plays an important role in causing the changes.
    Peter Slater, Professor of Materials Chemistry and Co-Director of the Birmingham Centre for Energy Storage at the University of Birmingham, said: “This discovery was almost an accident. We ball milled lithium molybdate as a model system to explore oxygen redox in batteries, and noticed that there was a phase transformation to the high-pressure spinel polymorph, a specific crystal structure that has only previously been made under high-pressure conditions.
    “Local heating alone could not explain this transformation. To test this theory, we then ball milled three other battery materials and our findings from these milling experiments reinforced our conclusion that local heating could not be the only reason for these changes.”
    The researchers also found that applying heat would cause some compounds to return to their pre-milled state, signifying that an additional variable was at play in the original synthesis: pressure being key. More

  • 75 Shares199 Views

    in Computers Math

    Accelerating sustainable semiconductors with ‘multielement ink’

    Semiconductors are the heart of almost every electronic device. Without semiconductors, our computers would not be able to process and retain data; and LED (light-emitting diode) lightbulbs would lose their ability to shine.
    But semiconductor manufacturing requires a lot of energy. Forming semiconductor materials from sand (silicon oxide) consumes a significant amount of heat-intensive energy, at scorching temperatures of around 2,700 degrees Fahrenheit. And the process of purifying and assembling all the raw materials that go into making a semiconductor can take weeks if not months.
    A new semiconducting material called “multielement ink” could make that process significantly less heat-intensive and more sustainable. Developed by researchers from Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley, “multielement ink” is the first “high-entropy” semiconductor that can be processed at low-temperature or room temperature. The breakthrough was recently reported in the journal Nature.
    “The traditional way of making semiconductor devices is energy-intensive and one of the major sources of carbon emissions,” said Peidong Yang, the senior author on the study. Yang is a faculty senior scientist in Berkeley Lab’s Materials Sciences Division and professor of chemistry and materials science and engineering at UC Berkeley. “Our new method of making semiconductors could pave the way for a more sustainable semiconductor industry.”
    The advance takes advantage of two unique families of semiconducting materials: hard alloys made of high-entropy semiconductors; and a soft, flexible material made of crystalline halide perovskites.
    High-entropy materials are solids made of five or more different chemical elements that self-assemble in near-equal proportions into a single system. For many years, researchers have wanted to use high-entropy materials to develop semiconducting materials that self-assemble with minimal energy inputs.
    “But high-entropy semiconductors have not been studied to nearly the same extent. Our work could help to significantly fill in that gap of understanding,” said Yuxin Jiang, co-first author and graduate student researcher in the Peidong Yang group with Berkeley Lab’s Materials Sciences Division and the department of chemistry at UC Berkeley. More

  • 88 Shares129 Views

    in Computers Math

    Wearable patch wirelessly monitors estrogen in sweat

    The sex hormone commonly known as estrogen plays an important role in multiple aspects of women’s health and fertility. High levels of estrogen in the body are associated with breast and ovarian cancers, while low levels of estradiol can result in osteoporosis, heart disease, and even depression. (Estrogen is a class of hormones that includes estradiol as the most potent form). Estradiol is also necessary for the development of secondary sexual characteristics in women and regulates the reproductive cycle.
    Because of its many functions, the hormone estradiol is often specifically monitored by physicians as part of women’s health care, but this usually requires the patient to visit a clinic to have blood drawn for analysis in a lab. Even at-home testing kits require samples of blood or urine to be mailed to a lab.
    But now Caltech researchers have developed a wearable sensor that monitors estradiol by detecting its presence in sweat. The researchers say the sensor may one day make it easier for women to monitor their estradiol levels at home and in real time.
    The research was conducted in the lab of Wei Gao, assistant professor of medical engineering, investigator with the Heritage Medical Research Institute, and Ronald and JoAnne Willens Scholar. In recent years, Gao has developed sweat sensors that detect cortisol, a hormone associated with stress; the presence of the COVID-19 virus; a biomarker indicating inflammation in the body; and a whole slew of other nutrients and biological compounds.
    Gao says the development of the estradiol sensor was spurred in part by requests from people who were unsatisfied with the options they had for monitoring their estrogen levels and had seen his previous work.
    “People often ask me if I could make the same kind of sweat sensor for female hormones, because we know how much those hormones impact women’s health,” Gao says.
    One population of women who would benefit from estradiol monitoring are those who are attempting to conceive a child, either naturally or through in vitro fertilization. The success of either method is dependent on getting timing right with regards to ovulation, but not all women have a reproductive cycle that follows a regular schedule. Some women have been able to track their ovulation by monitoring their body temperature, but Gao says that method has limited usefulness because it’s not very accurate and body temperature doesn’t increase until ovulation has begun. More

  • 138 Shares169 Views

    in Heart

    New computer analysis hints volcanism killed the dinosaurs, not an asteroid

    For decades, scientists have vigorously debated whether an asteroid strike or massive volcanic eruptions ended the reign of the dinosaurs 66 million years ago. Roughly three-quarters of all life on Earth, including all nonbird dinosaurs, went extinct at that time, putting a dramatic end to the Cretaceous Period.

    Now, researchers have devised a new way to identify the true dino killer: Let computers take a crack at it.

    The result of that computational effort suggests that massive bursts of gas produced by the Deccan Traps eruptions were solely capable of causing the extinction event, the team reports in the Sept. 29 Science. Those eruptions, which lasted roughly a million years, spewed massive amounts of gas-ridden lava across what’s now western India.

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    “Rather than come at it from the perspective of ‘let’s blame the volcanoes and explain why’ or ‘let’s blame asteroids and explain why,’” the goal was to have as little human input or bias in the process as possible, says Dartmouth computational geologist Alexander Cox.

    The idea was to work backward using evidence from the scene of the crime. Scientists do have a smoking gun: Cores drilled into deep-ocean sediments contain geologic data pointing to deadly bursts of gas to the atmosphere, particularly planet-warming carbon dioxide and ocean-acidifying sulfur dioxide.

    But such gases could have come from the asteroid strike, as it incinerated rocks on the planet’s surface, Cox says, or from the Deccan Traps eruptions.

    Previous efforts to understand the source of the gases have focused on timing, examining pulses of lava emplacement during the Deccan Traps eruptions, Cox says (SN: 2/21/19). But “we only have best guesses about how much initial gas was in [the lava].” Estimated carbon dioxide concentrations in the lava, for example, vary by an order of magnitude, he says. “So that’s why we approached this from a gas-emissions perspective rather than a lava-flow perspective.”

    Vast hardened lava flows, known as the Deccan Traps, cover much of what’s now western India. The lava is the remnant of a massive volcanic event about 66 million years ago. New computer analyses suggest that gases emitted during this event were enough to shift Earth’s temperature and may have led to the demise of nonbird dinosaurs.Baajhan at English Wikipedia

    To disentangle the relative contributions of each potential culprit, Cox and Dartmouth geologist C. Brenhin Keller used a statistical model called a Markov chain Monte Carlo approach. That approach systematically considers the probability of different scenarios of gas emissions from the different sources, converging toward possible solutions as the results of the simulations move closer and closer to geologic observations.

    What made the researchers’ approach particularly powerful is that they harnessed 128 different processors to run scenarios in parallel, Cox says. “All the processors then compared how they’re doing at the end of every model run, like classmates comparing answers.” That parallel computing meant that computations that would otherwise have taken a year took only a few days.

    The observations Cox and Keller used were data collected from three cores drilled into deep-sea sediments, each spanning 67 million to 65 million years ago. In those sediments are foraminifera, ocean-dwelling microorganisms whose carbonate shells contain different isotopes, or forms, of carbon and oxygen. The shells’ chemical makeup records the ocean chemistry at the time of their formation, and so can be used as a proxy to infer past global temperatures as well as how many creatures were thriving in the oceans, and how much carbon was moving between the atmosphere, ocean and land (SN: 1/16/20).

    The computer simulations determined that the amount of gas spewed into the atmosphere from the volcanism alone was enough to account for the changes in temperature and carbon cycling determined from the foraminifera data in the drill cores.

    As for the asteroid strike, which formed the massive Chicxulub crater in what’s now Mexico, it probably did not produce a big spike in carbon dioxide or sulfur dioxide, the analysis found (SN: 1/25/17).

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    But many scientists are not convinced that these findings provide the ultimate answer to this long-standing, complex question. “It’s an elegant way to address this problem,” says Sierra Petersen, a geochemist at the University of Michigan in Ann Arbor. Modeling in this way “gives the freedom to find the consensus solution, taking multiple proxy records into account. However, like any model, output depends on input.”

    Petersen notes that foraminifera shells are not an ideal proxy for ancient temperatures: The oxygen isotope ratios in foraminifera shells can change not only due to temperature but also due to seawater composition. Different temperature proxies would likely lead to different patterns of gas release reproduced in models, Petersen says.

    As for the mass extinction culprit, she adds, “it’s a bit of a leap to say that this study shows the impact didn’t cause the extinction. I think what they show is that the impact was likely not associated with a large [gas] release.” But the asteroid, she says, still could have had other deadly impacts on the planet’s environment.  

    Indeed, “the Chicxulub impact led to many devastating effects beyond the carbon dioxide and sulfur dioxide emissions explored in this study,” says Clay Tabor, a paleoclimatologist at the University of Connecticut in Storrs.

    Those include massive clouds of soot and dust kicked up from pulverized rocks due to the impact, he says. Previous research has suggested this dust may have dimmed the amount of sunlight reaching the Earth by as much as 20 percent, inducing a frigid winter that swiftly killed off plants and destroyed habitats (SN: 7/17/20).

    What’s more, the new study suggests that the asteroid impact didn’t have a long-term effect on the planet’s carbon cycle, based on carbon isotope data recorded in the foraminifera shells for the million years after the extinction. But there was an abrupt drop in the abundance of those creatures corresponding to the time of the impact, Tabor says. “The rapid rate of change caused by the Chicxulub impact was likely responsible for its effects on life.”

    “Many geochemical records spanning the [extinction event], as well as this modeling work, cannot capture well the rates of change associated with the Chicxulub impact,” he says. “The impact may have released significantly less CO2 and SO2 than the Deccan Traps, but it did so almost instantaneously.” So even if the asteroid impact released fewer gases overall, Tabor says, the speediness of that release could have been devastating all the same. More

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    in Space & Astronomy

    New JWST images suggest our understanding of the cosmos is flawed

    The greatest puzzle in cosmology just got even more puzzling.

    Images from the James Webb Space Telescope have confirmed that the universe appears to be expanding significantly faster than it should be, researchers report in a study accepted in the Astrophysical Journal. The observation is in conflict with an esteemed theory, the standard model of cosmology, that describes how the universe has evolved since the first moments after the Big Bang.

    The conflict comes down to calculations of the Hubble constant, a number that describes how fast everything in the universe is flying apart. One calculation, based on Planck satellite observations of the oldest light in the universe in conjunction with the standard model of cosmology, suggests the Hubble constant is 67.4 kilometers per second per megaparsec (a megaparsec is about 3 million light-years). Hubble Space Telescope images of stars at various distances from us provide a fundamentally incompatible value — 73 kilometers per second per megaparsec.

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    The discrepancy is known as the Hubble tension, and new JWST data hasn’t done anything to ease it (SN: 7/30/19). The telescope took images of the same stars as the Hubble telescope and calculated a very similar Hubble constant. Although the Planck number disagrees from the Hubble telescope and JWST number by less than 10 percent, the discrepancy in the measurements implies that there’s something terribly wrong with our understanding of the universe. Unless an error turns up in one of the measurements, it will take strange new physics to explain the tension.

    “Papers in the literature over the last 10 years have invoked anything from weird dark matter to weird dark energy, to another [exotic] particle, to a magnetic field in the early universe to a new field, all kinds of things” to explain the Hubble tension, says cosmologist Adam Riess of Johns Hopkins University.

    Some of these explanations “look semi-successful, some of them look like failures, some of them would cause other problems,” he says. Developing a theory that might resolve the tension “is still very much in the skunkworks [or extremely speculative] stage of trying to understand what [the tension] could mean.”

    JWST looks to the stars to calculate the Hubble constant

    With the Hubble telescope and JWST, astronomers calculate the Hubble constant by observing flashing stars known as Cepheid variables. The stars flare up periodically at rates that indicate how much light they’re putting out. Comparing a star’s brightness in telescope images with its expected brightness, based on the flare-up rates, gives a measure of the distance to the stars. Shifts in the color of the light coming from the stars reveal how fast they’re moving. Combining distance and speed observations of Cepheid stars leads to a measure of the expansion of the universe.

    But Cepheid variable stars tend to sit deep inside galaxies, surrounded by crowds of other stars. That can make it difficult to get good measurements of the Cepheids’ speeds and locations. One simple resolution for the Hubble tension could have been that the Hubble telescope measurements were simply off.

    Enter JWST, which can peer through the stellar crowds to clearly make out the color and brightness of Cepheid variables. The higher-resolution JWST images provide data with dramatically lower uncertainties and reduced confusion with nearby stars than the Hubble telescope could manage. The result: The Hubble telescope measurements have been right all along, Riess and colleagues report in their new paper.   

    This study alone isn’t enough to convince astronomer Wendy Freedman of the University of Chicago. The two galaxies studied are comparatively close to us, on cosmic scales, with the farthest one about 75 million light-years away, she notes. The relative proximity makes it easier to pick out the Cepheids from the stellar crowds. Freedman suspects it will be harder to distinguish Cepheids from the crowds of surrounding stars in more distant galaxies, even with JWST.

    “The problem is only going to be worse,” Freedman says. “Because the resolution, it gets worse as you go to a higher distance.” For very distant galaxies, she suspects, stars could appear too close together to pick out the Cepheids from neighboring stars, even for JWST. As a result,  Freedman says that Riess’ confirmation of the higher Hubble constant may crumble with analysis of more distant Cepheids.

    Patterns in this Planck satellite image of the cosmic microwave background, the oldest light in the universe, suggest that the universe is expanding at 67.4 kilometers per second per megaparsec, according to the standard model of cosmology.ESA and the Planck Collaboration

    JWST’s images leave the Hubble tension untouched

    Hints that the measurements might hold up at larger distances arose in a Sept. 12 presentation at a conference in Baltimore dedicated to the first year of JWST science. Riess showed preliminary Cepheid data from four more galaxies. One of them is 140 million light-years away — among the most distant galaxies in the Hubble telescope Cepheid studies. JWST data from those stars also line up with the Hubble telescope measurements. Although still awaiting peer review, the images strongly suggest that the JWST has indeed overcome the uncertainties that resulted when light from Cepheids got mixed up with light from nearby stars in the lower resolution Hubble telescope images.

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    University of Cambridge astrophysicist George Efstathiou, who was not involved in the study, is both convinced that Riess has gotten the measurements right and confounded by the implications. “When they showed me all of that [data],” Efstathiou says, “my reaction was, ‘Well, you know, I’m stumped.’”

    Efstathiou is a member of the Planck satellite collaboration, which studied the oldest light in the universe, called the cosmic microwave background, and found the lower value for the expansion of the universe. The satellite’s calculation is based on images of the patterns in light from the early universe. Together with the standard model of cosmology, the images show that the universe is expanding with a Hubble constant that’s lower than the JWST measurement by about 5.6 kilometers per second per megaparsec.

    As it stands, there doesn’t seem to be anything wrong with the Planck measurement of the Hubble constant or with the JWST observations. The tension between the measurements points a finger at the standard model of cosmology as the problem. But the standard model also appears to be unimpeachable; it’s withstood numerous other challenges without breaking down. The model came about in part due to the discovery of the accelerating expansion of the universe, which earned Riess and others a Nobel Prize in physics (SN: 10/4/11). The revelation was a key piece in shaping the model to include dark matter, dark energy and other factors, making it the simplest theory that can accurately describe the universe.

    Now, though, Riess’ Cepheid-based studies of the Hubble constant show that there’s still more to learn.

    “This is a crack, or a surprise that doesn’t fit,” Riess says. “It’s left us more in a kind of confused or purgatory state.” The implication, he says, is “there’s a problem with the standard model. You can revise it, but we don’t know how to revise it, which direction or in what way.”

    People shouldn’t mistake the tension over the Hubble tension as despair. “It’s more of an opportunity to learn something about the universe with these telescopes,” Riess says.

    One possibility is completely new physics.

    “If there’s new physics, that’d be fun,” Freedman says. “We’d all like to see something new and interesting…. Either way, I think it’s going to be an exciting result — either confirming the [standard] model or showing that there’s something still in the model that’s missing.” More

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    in Computers Math

    Sperm swimming is caused by the same patterns that are believed to dictate zebra stripes

    Patterns of chemical interactions are thought to create patterns in nature such as stripes and spots. This new study shows that the mathematical basis of these patterns also governs how sperm tail moves.
    The findings, published today in Nature Communications, reveal that flagella movement of, for example, sperm tails and cilia, follow the same template for pattern formation that was discovered by the famous mathematician Alan Turing.
    Flagellar undulations make stripe patterns in space-time, generating waves that travel along the tail to drive the sperm and microbes forward.
    Alan Turing is most well-known for helping to break the enigma code during WWII. However he also developed a theory of pattern formation that predicted that chemical patterns may appear spontaneously with only two ingredients: chemicals spreading out (diffusing) and reacting together. Turing first proposed the so-called reaction-diffusion theory for pattern formation.
    Turing helped to pave the way for a whole new type of enquiry using reaction-diffusion mathematics to understand natural patterns. Today, these chemical patterns first envisioned by Turing are called Turing patterns. Although not yet proven by experimental evidence, these patterns are thought to govern many patterns across nature, such as leopard spots, the whorl of seeds in the head of a sunflower, and patterns of sand on the beach. Turing’s theory can be applied to various fields, from biology and robotics to astrophysics.
    Mathematician Dr Hermes Gadêlha, head of the Polymaths Lab, and his PhD student James Cass conducted this research in the School of Engineering Mathematics and Technology at the University of Bristol. Gadêlha explained: “Live spontaneous motion of flagella and cilia is observed everywhere in nature, but little is known about how they are orchestrated.
    “They are critical in health and disease, reproduction, evolution, and survivorship of almost every aquatic microorganism in earth.”
    The team was inspired by recent observations in low viscosity fluids that the surrounding environment plays a minor role on the flagellum. They used mathematical modelling, simulations, and data fitting to show that flagellar undulations can arise spontaneously without the influence of their fluid environment. More

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    in Computers Math

    Revolutionary breakthrough: Human stomach micro-physiological system unveiled

    A groundbreaking development in biomedical engineering has led to the creation of a human stomach micro-physiological system (hsMPS), representing a significant leap forward in understanding and treating various gastrointestinal diseases, including stomach cancer. The research team, led by Professor Tae-Eun Park from the Department of Biomedical Engineering at UNIST and Professor Seong-Ho Kong from Seoul National University Hospital, has successfully developed a biomimetic chip that combines organoid and organ-on-a-chip technologies to simulate the complex defense mechanisms of the human gastric mucosa.
    Organoids, which mimic human organs using stem cells, have shown great potential as in vitro models for studying specific functions. However, they lack the ability to replicate mechanical stimulation or cell-to-cell interactions found within the human body. This limitation prompted researchers to develop an innovative biochip capable of recreating real-life gastric mucosal protection systems.
    The newly developed biochip incorporates fluid flow within its microfluidic channels to simulate mechanical stimuli and facilitate cell-to-cell interactions. Mesenchymal substrate cells exposed to fluid flow activate gastric stem cell proliferation while promoting cellular differentiation balance. This process ultimately mimics key features necessary for developing functional gastric mucosal barriers at a biologically relevant level.
    One remarkable achievement demonstrated by this hsMPS is its ability to uncover previously unseen defense mechanisms against Helicobacter pylori — a pathogen associated with various stomach diseases — in ways that were not possible with existing models. Gastric mucosal peptide known as TFF1 was observed forming mosaic-like structures within groups infected with Helicobacter pylori — forming a protective barrier essential for establishing an efficient defense system against external infectious factors. Suppression of gastric mucosal peptide expression resulted in more severe inflammatory reactions.
    “This study presents our model’s potential for observing dynamic interactions between epithelial cells and immune cells in chips infected with Helicobacter pylori, contributing to a comprehensive understanding of gastric mucosal barrier stability,” explained Professor Park.
    The research findings, supported by the Basic Research Laboratory (BRL) research grant from the National Research (NRF), funded by the Ministry of Science and ICT (MSIT), have been published online on July 31 in Advanced Science.
    These groundbreaking advancements in hsMPS open up new avenues for studying host-microbe interactions, developing therapeutic strategies for gastric infections, and gaining a deeper understanding of gastrointestinal diseases. This innovative biochip technology has the potential to reduce reliance on animal experimentation while providing valuable insights into complex physiological processes within the human stomach. More