"Researchers at Purdue University have developed a new chemical process that they say can convert approximately one-quarter of the world's plastic waste into gasoline and diesel-like fuels," writes Slashdot reader dmoberhaus. Motherboard explains how it works: As detailed in a paper published this week in Sustainable Chemistry and Engineering, the chemists discovered a way to convert polypropylene -- a type of plastic commonly used in toys, medical devices, and product packaging like potato chip bags -- into gasoline and diesel-like fuel. The researchers said that this fuel is pure enough to be used as blendstock, a main component of fuel used in motorized vehicles. Polypropylene waste accounts for just under a quarter of the estimated 5 billion tons of plastic that have amassed in the world's landfills in the last 50 years.

To turn polypropylene into fuel, the researchers used supercritical water, a phase of water that demonstrates characteristics of both a liquid and a gas depending on the pressure and temperature conditions. Purdue chemist Linda Wang and her colleagues heated water to between 716 and 932 degrees Fahrenheit at pressures approximately 2300 times greater than the atmospheric pressure at sea level. When purified polypropylene waste was added to the supercritical water, it was converted into oil within in a few hours, depending on the temperature. At around 850 degrees Fahrenheit, the conversion time was lowered to under an hour. The byproducts of this process include gasoline and diesel-like oils. According to the researchers, their conversion process could be used to convert roughly 90 percent of the world's polypropylene waste each year into fuel.

Zorro shares a report from the Smithsonian: A recent study used machine learning technology to analyze eight leading models of human origins and evolution, and the program identified evidence in the human genome of a "ghost population" of human ancestors. The analysis suggests that a previously unknown and long-extinct group of hominins interbred with Homo sapiens in Asia and Oceania somewhere along the long, winding road of human evolutionary history, leaving behind only fragmented traces in modern human DNA. The study, published in Nature Communications, is one of the first examples of how machine learning can help reveal clues to our own origins. By poring through vast amounts of genomic data left behind in fossilized bones and comparing it with DNA in modern humans, scientists can begin to fill in some of the many gaps of our species' evolutionary history. "The new data suggest that the mysterious hominin was likely descended from an admixture of Neanderthals and Denisovans (who were only identified as a unique species on the human family tree in 2010)," the report adds. "Such a species in our evolutionary past would look a lot like the fossil of a 90,000-year-old teenage girl from Siberia's Denisova cave. Her remains were described last summer as the only known example of a first-generation hybrid between the two species, with a Neanderthal mother and a Denisovan father."

David Aguila, a 19-year-old bioengineering student at the Universitat Internacional de Catulunya in Spain, has built himself a robotic prosthetic arm using Lego pieces. David was born with Poland syndrome that affects his right peck and right arm. From a report: Once his favorite toys, the plastic bricks became the building material for Mr Aguilar's first, still very rudimentary, artificial arm at the age of nine, and each new version had more movement than the one before. He uses the artificial arm only occasionally and is self-sufficient without it, with all the versions on display in his room in the university residence on the outskirts of Barcelona. In November 2017 Mr Aguilar, who uses Lego pieces provided by a friend, proudly displayed a fully functional red and yellow robotic arm, built when he was 18, bending it in the elbow joint and flexing the grabber.

The latest models are marked MK followed by the number -- a tribute to comic book superhero Iron Man and his MK armor suits. The MK II was a predominantly blue model built from a Lego plane set, including a motor, while MK III was created from a set for a piece of mining equipment. After graduating from university, he wants to create affordable prosthetic solutions for people who need them.

Wave723 shares a report from IEEE Spectrum: A new kind of magnet, theorized for decades, may now have been experimentally proven to exist. And it could eventually lead to better data storage devices. In a normal magnet, the magnetic moments of individual grains align with each other to generate a magnetic field. In contrast, in the new "singlet-based" magnet, magnetic moments are temporary in nature, popping in and out of existence. Although a singlet-based magnet's field is unstable, the fact that such magnets can more easily transition between magnetic and non-magnetic states can make them well-suited for data storage application. Specifically, they could operate more quickly and with less power than conventional devices, says Andrew Wray, a materials physicist at New York University who led the research. Now, Wray and his colleagues have discovered the first example of a singlet-based magnet that is robust -- one made from uranium antimonide (USb2). "It ends up taking very little energy to create spin excitons for uranium antimonide," Wray says. "This is essential for the singlet-based magnet, because if it took a lot of energy, then there wouldn't be enough spin excitons to condense, stabilize one another, and give you a magnet." The research has been published in the journal Nature Communications.

Nasa's InSight Mars lander has placed a domed shield over its seismometer, completing that instrument's deployment. From a report: The seismometer will look for evidence of ongoing seismic activity on the red planet to provide data about the deep interior of Mars. This will help scientists determine how the planet formed. The seismometer, called the seismic experiment for interior structure (Seis), is the lander's highest priority science instrument. It is needed to complete about three-quarters of the mission's scientific objectives. The spacecraft touched down on 26 November 2018. On 19 December, a robotic arm picked up the instrument from its storage position and placed it on the martian surface about 1.6 metres away from the spacecraft.

From Nature magazine: Female Aedes aegypti, like other mosquito species, feed on blood to get the protein they need to produce their eggs, and spread diseases such as dengue in the process. But once the mosquitoes have had their blood fix, they stop biting until they've laid their eggs several days later. Leslie Vosshall, a neurobiologist at the Rockefeller University in New York City, wondered whether she could hijack this biological process to switch off a mosquito's appetite.

Previous research had suggested that a mosquito's desire to feed is controlled by neuropeptides, molecules used by the nervous system to communicate. Vosshall and her team suspected that neuropeptide Y (NPY) receptors might be particularly important, because they form part of the molecular pathway involved in food-seeking behaviour for many animals -- including humans. Some human appetite-suppressant drugs already target the NPY receptors, so Vosshall decided to take a "completely zany" approach: feed these drugs to mosquitoes and see what happens. The method worked: mosquitoes that fed on a solution containing NPY-activating drugs were much less likely to approach a human-scented 'lure' than were the control group, and their appetites remained suppressed for two days. Further reading: A New Way to Keep Mosquitoes From Biting.