Susanne Rust of the Los Angeles Times reports (paywalled) that industry executives knew for decades that microplastics were infiltrating the human body. Slashdot reader joshuark shares an excerpt from the report: Scientists today say we're just beginning to understand the harm that the tiny bits of plastic we drink, eat and breathe are doing to the human body. Internal memos among company scientists and executives obtained by The Times reveal that for at least half a century, the plastics industry has been aware of and concerned about the potential for microplastic contamination in the human body. But recently discovered chemical company documents dating back several decades show that industry scientists have long been aware of -- and concerned about -- the way microplastic particles migrate beyond the gut in animals and humans, depositing in important organs. And the potential for that knowledge to affect the plastic food packaging industry. Their concern goes back to 1974 and a scientific meeting at a New York City hotel, where a German gastroenterologist presented a scientific paper that showed for the first time that ingested particles like microplastics could infiltrate the rest of the body. His presentation was largely overlooked by the government scientists in attendance but became a point of worried discussion among company scientists. Tracey Woodruff, professor of epidemiology and population health at Stanford University, who reviewed the documents, said they indicate scientists and executives at major chemical companies have known and remained silent even as microplastics accumulated in tissues. She likened it to other industries that knew about pollutants -- greenhouse gases, asbestos and tobacco -- but did not take action to make them safer. A spokesperson with the chemical industry's largest trade group took issue with that characterization. "Scientific debate over what the evidence shows is not silence. It is how sound science and effective policy advance," said Craig Davis, senior director of plastics chemistry at the American Chemistry Council. "Our industry is committed to advancing microplastics science by supporting independent research and policies that would do so."

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Physicists at Northwestern University have successfully trapped a single positron for an entire month, allowing researchers to study its quantum properties with unprecedented precision. "Further investigations using the trap might reveal the secret of why the world around us is made of matter and not antimatter, when things could have presumably gone either way," reports Scientific American. From the report: Every normal particle of matter has an antimatter counterpart with equal mass but opposite charge. To build their trap, physicists started with atoms of sodium 22, a radioactive isotope with a half-life of about two and a half years. When one of these atoms decays, it emits a positron -- the antimatter counterpart of the electron. "The big challenge is to persuade these positrons to slow down and then capture them," says Gerald Gabrielse, a physicist at Northwestern University, who oversaw the project. The team reported its achievement on Wednesday in Physical Review Letters (PDF). The first step is to send the positrons through the crystal lattice of a sliver of cold tungsten. As the particles go pinballing through the material, they slow down and lose energy. "Every time they bang into something, there's a chance of annihilation, but it doesn't always happen," Gabrielse says. "If they make it to the end, they get popped out." Next, the physicists steer the positrons along a channel using electromagnetic fields. Eventually the particles end up in a vacuum, just three tenths of a degree Celsius above absolute zero, trapped by an electric field on top and bottom and a magnetic field on the sides. "If you want to hold on to antimatter, you have to hold it in a container without walls," Gabrielse says. This method allowed the researchers to isolate and study a solitary, lone positron for a monthâ"and could let them do so indefinitely. The researchers intend to use their trap to make precise measurements of the positron's magnetic moment -- basically the strength and orientation of its magnetic field. To do this, they must determine two things: the energy needed to flip the direction of the positron's spin and the energy needed to make it jump from its ground state to its first excited state. Using a similar trap setup, Gabrielse and his team have already measured the magnetic moment of an electron to a precision of one part in 10 trillion. Taking the equivalent measurement for a positron will allow them to make a crucial comparison. "We're looking to see if they have an exactly opposite magnetic moment," Gabrielse says. That's the prediction of the Standard Model of particle physics. If the two have different values, however, this could help explain why our universe is made of matter instead of antimatter.

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Timekeepers have officially voted to eliminate the leap second, allowing Coordinated Universal Time to drift as much as one hour from Earth's rotation before a correction is needed. The change ends decades of occasionally adding or subtracting seconds and replaces it with a hypothetical "leap hour" that likely wouldn't be necessary for hundreds or even thousands of years. Smithsonian Magazine reports: "It's kind of a philosophical discussion, because if a leap hour happens, it won't be for a very, very long time," Christian Bizouard, director of the IERS Earth Orientation Center in France, tells the Guardian's Ian Sample. "What we are doing is pushing back the decision." The move caps off 30 years of debate, as the leap second has been highly controversial in the world of timekeeping. Leap seconds aren't nearly as smooth of a fix as leap years are, and they can cause computer and website issues. Reddit famously crashed when a leap second was added on June 30, 2012. It's "always been a problem," Judah Levine, a former researcher at the NIST's Time and Frequency Division, tells Scientific American's Emma Gometz. Instead of adding the entire second all at once, companies such as Google and Meta add the extra time in smaller segments in a tactic called "smearing," according to the Conversation. It's not a simple task, however, and companies that employ smearing have long lobbied to get rid of the leap second. What's more, with Earth's recent spin acceleration, timekeepers around the world were facing the possibility of the world's first negative leap second, in which a second would be subtracted from UTC. This sparked fears, akin to those surrounding Y2K, that our modern technologies wouldn't be able to handle such a change. "It's never happened before, and therefore the software for that has never been tested," Darryl Veitch, a researcher who leads the Timing Lab at the University of Technology Sydney, tells the Australian Broadcasting Corporation's Ellen Phiddian. But others argued that it wouldn't be much of a problem. The vote means that in the future, UTC will be allowed to diverge from astronomical time more than ever before.

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Researchers have created a strengthened "BioPykrete" by combining ice with cellulose nanocrystals and a custom protein that binds the plant-based crystals to the ice structure. In small-scale tests, the material was about 10 times stronger than regular ice and absorbed 70 times more energy before breaking. ScienceAlert reports: Instead of wood pulp's larger, disordered fibers, the researchers used cellulose nanocrystals here. Cellulose is the main structural material in plants, and in nanocrystal form, it can act as a microscopic strengthening agent for other materials, including ice -- essentially stopping cracks from spreading easily. The protein used here was called CBM3a-AFPIII, a combination of an antifreeze protein (AFP) and a carbohydrate-binding module (CBM). Its job was to act like glue, keeping the cellulose nanocrystals and ice bonded together. It's a clever approach, and the researchers think that by tweaking their ingredients and methods, they might be able to improve their 'super ice' even further. "Optimizing solidification kinetics and freezing protocols, alongside developing diverse AFP-CBM variants, could yield even higher-strength composites," write the researchers. Besides further tests of the durability of the material, the researchers are also keen to take a closer look at how cracks propagate through BioPykrete, to confirm that the underlying strengthening mechanisms are what they think they are. Further down the line, this approach could open up a whole new landscape for materials used in packaging, construction, and more: Using a custom protein to bring two unlikely compounds (ice and cellulose) together. "By bridging the gap between recombinant protein design and structural engineering, we have developed a high-performance material specifically engineered for the rigors of the world's most extreme environments," write the researchers. The findings have been published in the journal Colloids and Surfaces B: Biointerfaces.

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