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      This stretchy electronic material hardens upon impact just like “oobleck”

      news.movim.eu / ArsTechnica · 7 days ago - 17:13 · 1 minute

    This flexible and conductive material has “adaptive durability,” meaning it gets stronger when hit.

    Enlarge / This flexible and conductive material has “adaptive durability,” meaning it gets stronger when hit. (credit: Yue (Jessica) Wang)

    Scientists are keen to develop new materials for lightweight, flexible, and affordable wearable electronics so that, one day, dropping our smartphones won't result in irreparable damage. One team at the University of California, Merced, has made conductive polymer films that actually toughen up in response to impact rather than breaking apart, much like mixing corn starch and water in appropriate amounts produces a slurry that is liquid when stirred slowly but hardens when you punch it (i.e., "oobleck"). They described their work in a talk at this week's meeting of the American Chemical Society in New Orleans.

    "Polymer-based electronics are very promising," said Di Wu, a postdoc in materials science at UCM. "We want to make the polymer electronics lighter, cheaper, and smarter. [With our] system, [the polymers] can become tougher and stronger when you make a sudden movement, but... flexible when you just do your daily, routine movement. They are not constantly rigid or constantly flexible. They just respond to your body movement."

    As we've previously reported , oobleck is simple and easy to make. Mix one part water to two parts corn starch, add a dash of food coloring for fun, and you've got oobleck, which behaves as either a liquid or a solid, depending on how much stress is applied. Stir it slowly and steadily and it's a liquid. Punch it hard and it turns more solid under your fist. It's a classic example of a non-Newtonian fluid.

    In an ideal fluid , the viscosity largely depends on temperature and pressure: Water will continue to flow regardless of other forces acting upon it, such as being stirred or mixed. In a non-Newtonian fluid, the viscosity changes in response to an applied strain or shearing force, thereby straddling the boundary between liquid and solid behavior. Stirring a cup of water produces a shearing force, and the water shears to move out of the way. The viscosity remains unchanged. But for non-Newtonian fluids like oobleck, the viscosity changes when a shearing force is applied.

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      Building robots for “Zero Mass” space exploration

      news.movim.eu / ArsTechnica · Thursday, 8 February - 19:17

    A robot performing construction on the surface of the moon against the black backdrop of space.

    Enlarge (credit: NASA )

    Sending 1 kilogram to Mars will set you back roughly $2.4 million, judging by the cost of the Perseverance mission. If you want to pack up supplies and gear for every conceivable contingency, you’re going to need a lot of those kilograms.

    But what if you skipped almost all that weight and only took a do-it-all Swiss Army knife instead? That’s exactly what scientists at NASA Ames Research Center and Stanford University are testing with robots, algorithms, and highly advanced building materials.

    Zero mass exploration

    “The concept of zero mass exploration is rooted in self-replicating machines, an engineering concept John von Neumann conceived in the 1940s”, says Kenneth C. Cheung, a NASA Ames researcher. He was involved in the new study published recently in Science Robotics covering self-reprogrammable metamaterials—materials that do not exist in nature and have the ability to change their configuration on their own. “It’s the idea that an engineering system can not only replicate, but sustain itself in the environment,” he adds.

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      Wearable solar-powered gadget automatically regulates body temperature

      news.movim.eu / ArsTechnica · Thursday, 4 January - 19:44

    Image of a smiling person inside a spacesuit, with a solar panel and the blackness of space behind him.

    Enlarge / While the devices probably aren't compact enough for casual wear, they could integrate with technical clothing. (credit: NASA )

    There is only so much heat—or cold—that the human body can take. This can be a problem in extreme environments, from subzero polar temperatures to the ruthless heat of the Sahara, and it doesn’t stop at Earth. Maintaining temperature is also an issue for astronauts. The vacuum of space is a gargantuan freezer, and exposure to direct sunlight out there can be just as brutal as the cold.

    Clothing tech that regulates body temperature usually goes only one way: heating or cooling. It also tends to be bulky and needs substantial energy that eventually drains any batteries. What if there was a system that both heat and cool while running on a constant renewable energy source?

    A team of researchers, led by Ziyuan Wang of Nankai University in Tianjin, China, has created a flexible, solar-powered device that can be incorporated into clothing and regulate the body by actively heating or cooling the skin. It also works continuously for 24 hours and only needs sunlight to recharge.

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      A locally grown solution for period poverty

      news.movim.eu / ArsTechnica · Saturday, 9 December - 13:08 · 1 minute

    Image of rows of succulents with long spiky leaves and large flower stalks.

    Enlarge / Sisal is an invasive species that is also grown agriculturally. (credit: Chris Hellier )

    Women and girls across much of the developing world lack access to menstrual products. This means that for at least a week or so every month, many girls don’t go to school , so they fall behind educationally and often never catch up economically.

    Many conventional menstrual products have traditionally been made of hydrogels made from toxic petrochemicals, so there has been a push to make them out of biomaterials. But this usually means cellulose from wood, which is in high demand for other purposes and isn’t readily available in many parts of the globe. So Alex Odundo found a way to solve both of these problems: making maxi pads out of sisal, a drought-tolerant agave plant that grows readily in semi-arid climates like his native Kenya.

    Putting an invasive species to work

    Sisal is an invasive plant in rural Kenya, where it is often planted as livestock fencing and feedstock. It doesn’t require fertilizer, and its leaves can be harvested all year long over a five- to seven-year span. Odundo and his partners in Manu Prakash’s lab at Stanford University developed a process to generate soft, absorbent material from the sisal leaves. It relies on treatment with dilute peroxyformic acid (1 percent) to increase its porosity, followed by washing in sodium hydroxide (4 percent) and then spinning in a tabletop blender to enhance porosity and make it softer.

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      Unlocking the secrets of oobleck—strange stuff that’s both liquid and solid

      news.movim.eu / ArsTechnica · Tuesday, 5 December - 18:55 · 1 minute

    child's hands pressing into a yellow gooey substance in a glass bowl.

    Enlarge / "Oobleck" is a classic kitchen science example of a shear-thickening non-Newtonian fluid. (credit: Screenshot/PBS )

    Oobleck has long been my favorite example of a non-Newtonian fluid , and I'm not alone . It's a hugely popular "kitchen science" experiment because it's simple and easy to make. Mix one part water to two parts corn starch, add a dash of food coloring for fun, and you've got oobleck, which behaves as either a liquid or a solid, depending on how much stress is applied. Stir it slowly and steadily, and it's a liquid. Punch it hard, and it turns more solid under your fist. You can even fill small pools with the stuff and walk across it since the oobleck will harden every time you step down—a showy physics demo that naturally shows up a lot on YouTube .

    The underlying physics principles of this simple substance are surprisingly nuanced and complex, and thus fascinating to scientists. Molecular engineers at the University of Chicago have used dense suspensions of piezoelectric nanoparticles to measure what is happening at the molecular level when oobleck transitions from liquid to solid behavior, according to a new paper published in the Proceedings of the National Academy of Sciences.

    Toward the end of his life, Isaac Newton laid out the properties of an "ideal liquid." One of those properties is viscosity , loosely defined as how much friction/resistance there is to flow in a given substance. The friction arises because a flowing liquid is essentially a series of layers sliding past one another. The faster one layer slides over another, the more resistance there is; the slower one layer slides over another, the less resistance there is. But the world is not an ideal place.

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      Google’s DeepMind finds 2.2M crystal structures in materials science win

      news.movim.eu / ArsTechnica · Wednesday, 29 November - 18:42

    Lab picture

    Enlarge / The researchers identified novel materials by using machine learning to first generate candidate structures and then gauge their likely stability. (credit: Marilyn Sargent/Berkeley Lab)

    Google DeepMind researchers have discovered 2.2 million crystal structures that open potential progress in fields from renewable energy to advanced computation, and show the power of artificial intelligence to discover novel materials.

    The trove of theoretically stable but experimentally unrealized combinations identified using an AI tool known as GNoME is more than 45 times larger than the number of such substances unearthed in the history of science, according to a paper published in Nature on Wednesday.

    The researchers plan to make 381,000 of the most promising structures available to fellow scientists to make and test their viability in fields from solar cells to superconductors. The venture underscores how harnessing AI can shortcut years of experimental graft—and potentially deliver improved products and processes.

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      Scientists 3D print a robotic hand with human-like bones and tendons

      news.movim.eu / ArsTechnica · Saturday, 18 November - 13:00 · 1 minute

    Image of a robotic hand made from light colored plastics grasping both a pen and a bottle in separate images.

    Enlarge / The 3D-printed hand made via the new method. (credit: ETH Zurich/Thomas Buchner )

    Have you ever wondered why robots are unable to walk and move their bodies as fluidly as we do? Some robots can run, jump, or dance with greater efficiency than humans, but their body movements also seem mechanical. The reason for this lies in the bones they lack.

    Unlike humans and animals, robots do not have real bones or the flexible tissues that connect them; they have artificial links and joints made of materials like carbon fiber and metal tubes. According to Robert Katzschmann, a professor of robotics at ETH Zurich, these internal structures allow a robot to make movements, grab objects, and maintain different postures. However, since links and joints are made up of hard materials, robot bodies are not as flexible, agile, and soft as human bodies. This is what makes their body movements so stiff.

    But they may not need to stay stiff for long. A team of researchers from the Swiss Federal Institute of Technology (ETH) Zurich and US-based startup Inkbit have figured out a way to 3D print the world’s first robotic hand with an internal structure composed of human-like bones, ligaments, and tendons. What makes the hand even more special is that it was printed using an entirely new 3D inkjet deposition method called vision-controlled jetting (VCJ).

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      Capacitor-based heat pumps see big boost in efficiency

      news.movim.eu / ArsTechnica · Thursday, 16 November - 20:00

    Thermal imaging of two heat pumps and fan units, showing red and orange areas with elevated temperatures.

    Enlarge (credit: FHM/Getty Images )

    Various forms of heat pumps—refrigerators, air conditioners, heaters—are estimated to consume about 30 percent of the world's electricity. And that number is almost certain to rise, as heat pumps play a very large role in efforts to electrify heating to reduce the use of fossil fuels.

    Most existing versions of these systems rely on the compression of a class of chemicals called hydrofluorocarbons, gasses that were chosen because they have a far smaller impact on the ozone layer than earlier refrigerants. Unfortunately, they are also extremely potent greenhouse gasses, with a short-term impact several thousand times that of carbon dioxide.

    Alternate technologies have been tested, but all of them have at least one major drawback in comparison to gas compression. In a paper released in today's issue of Science, however, researchers describe progress on a form of heat pump that is built around a capacitor that changes temperature as it's charged and discharged. Because the energy spent while charging it can be used on discharge, the system has the potential to be highly efficient.

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      This is how we could possibly build paved roads on the Moon

      news.movim.eu / ArsTechnica · Friday, 27 October - 23:38

    High detailed image of the moon

    Enlarge (credit: Master/Getty )

    The Moon is slated to be our next frontier. When Artemis 3 takes off (tentatively) near the end of 2025, it will be the first mission since the Apollo era to land humans on our satellite. By then, there might be a new way to get around on the Moon’s gray dust, which could at least mitigate damage from sharp particles of lunar regolith.

    An international team of researchers with the ESA PAVER project has figured out a way to melt Moondust—or at least an ESA-developed stimulant for it—with lasers. The researchers fired laser beams at lunar soil to create interlocking pavers that could be used to construct paved roads and landing pads. The hardened molten regolith is tough enough to withstand the weight of rovers and other spacecraft with minimal dust kickup, and it could all be made right there on the Moon.

    “This technology is envisioned to play a major role in the first phase (survivability) of lunar infrastructure and base development, and over time to contribute to all phases of lunar exploration,” the researchers said in a study recently published in Scientific Reports .

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