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Category: materials – Page 271

Scientists Finally Observe Long-Predicted Form of Magnetism

Scientists believe they’ve made a concrete example of an unusual, theoretical form of ferromagnetism first described by a researcher more than 50 years ago.

Nagaoka ferromagnetism, named for the scientist who discovered it, Yosuke Nagaoka, is a special case of the same magnetic forces that make regular, refrigerator-type magnets work—ferro meaning iron, plus a few other metals that are naturally receptive to magnetism. Identifying it in real life—in this case using a quantum system of electrons—can help scientists understand how spontaneous ferromagnetism works.

Plastic-eating caterpillars have gut bacteria that can live on polyethylene for over a year

“The problem of plastic pollution is too large to simply throw worms and there is still a lot to do before we can parlay this work into making a meaningful contribution,” Cassone said. “Also, the larvae tend to eat less plastic with longer times on that type of diet. By understanding the process – why the breakdown of plastic occurs so rapidly in the waxworm—we can then begin to develop ways to really make a meaningful impact to plastic pollution.”

He continued: “Now that we know the microbiome plays a role, if we can better understand how the bacteria works together with the worm and what kind of conditions cause it to flourish, perhaps this information can be used to design better tools to eliminate plastics from our environment.”

Not all are convinced, however. Till Opatz, from the Department of Chemistry at the Johannes Gutenberg University, Germany, was critical of the initial findings that caterpillars digest plastic. At the time he and his colleagues said they disagreed with the methodology and conclusions reported, adding the study “does not provide sufficient proof” that G. mellonella can chemically destroy polyethylene.

The caterpillar larvae ‘plastivores’ that consume and metabolize polyethylene

A team of researchers at Brandon University has found that greater wax moth caterpillar larvae are “plastivores” that are able to consume and metabolize polyethylene. In their paper published in Proceedings of the Royal Society B, the group describes their study of the caterpillars and what they learned about them and their gut microbiome.

Prior research has shown that plastics are becoming a major pollutant. In addition to piling up in landfills, they are also broken down into microplastics, which are polluting the world’s oceans. And while there have been some attempts to curb their use, they are still produced and used in abundance in many parts of the world. Thus, scientists have been searching for a way to force such materials to degrade faster—natural degradation takes approximately 100 years. In this new effort, the researchers studied wax moths and their larvae, which are known to invade beehives to eat the honeycombs inside.

The researchers with this new effort had learned of anecdotal evidence that the larvae, which exist as caterpillars, eat low-density polyethylene. To find out if this was true, they obtained multiple caterpillars and fed them a diet of plastic grocery bags. They found that 60 of the caterpillars were able to consume approximately 30 square centimeters of the plastic in a week. They also found that the caterpillars could survive for a week eating nothing but the plastic. The researchers also studied the gut microbiomes of several of the caterpillars and identified bacteria that were involved in digesting plastic. They also allowed some of the bacteria to feast on plastic outside of the caterpillar gut and found that some of them were able to survive for up to a year eating nothing but plastic.

The magnet that didn’t exist

In 1966, Japanese physicist Yosuke Nagaoka predicted the existence of a rather striking phenomenon: Nagaoka’s ferromagnetism. His rigorous theory explains how materials can become magnetic, with one caveat: the specific conditions he described do not arise naturally in any material. Researchers from QuTech, a collaboration between TU Delft and TNO, have now observed experimental signatures of Nagaoka ferromagnetism using an engineered quantum system. The results were published today in Nature.

Familiar magnets such as the ones on your refrigerator are an everyday example of a phenomenon called . Each electron has a property called ‘spin’, which causes it to behave like a miniscule magnet itself. In a ferromagnet, the spins of many electrons align, combining into one large magnetic field. This seems like a simple concept, but Nagaoka predicted a novel and surprising mechanism by which ferromagnetism could occur—one that had not been observed in any system before.

Researchers Work to Laser-Proof Ships

Circa 2008

Okay, so no one has quite perfected laser weapons yet, but that doesn’t mean you can’t at least think about possible defenses. Naval researchers are looking at materials that could deflect high-powered lasers, reports Discovery:

Laser_shield “If you have a ship being hit by a laser, and it was made of this metamaterial, you could reflect the laser beam,” said Simin Feng, one of the study co-authors and a researcher at China Lake.

Unlike normal materials, which derive their properties largely from the chemicals that comprise them, metamaterials are artificially made materials that get their properties from their physical structures.

The material Feng and her co-author Klaus Halterman, also of China Lake, have theorized would be made of three layers of conventional materials, with the metamaterials sandwiched between the three layers. Since the material would be thin it should be easily applied and “wouldn’t weigh things down,” said Halterman.

Advancement simplifies laser-based medical imaging

Photoacoustic imaging, a technique for examining living materials through the use of laser light and ultrasonic sound waves, has many potential applications in medicine because of its ability to show everything from organs to blood vessels to tumors.

Caltech’s Lihong Wang, a pioneer in the field, has developed variants of imaging that can show organs moving in real time, develop three-dimensional (3D) images of internal body parts, and even differentiate cancerous cells from healthy cells.

Wang, Bren Professor of Medical Engineering and Electrical Engineering, has now further advanced technology with what he calls Photoacoustic Topography Through an Ergodic Relay (PATER), which aims to simplify the equipment required for imaging of this type.

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