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Category: materials – Page 198

Surprising Colors with Scotch Tape

A physicist’s do-it-yourself art project makes vibrant images with a pair of polarizers and carefully placed layers of transparent tape.

When the COVID-19 pandemic shut down universities and offices across the world in spring 2020, finding new hobbies to stave off fear (and boredom) became paramount. While some took up cross-stitch or a new stretching routine, Aaron Slepkov, a photonics researcher at the University of Trent in Peterborough, Canada, turned to a physics-inspired art form called polage to occupy his time.

Polage, or polarization-filtered coloration, as Slepkov calls it, is a kind of collage that uses polarizers and thin films to create brightly colored artworks that transform depending on how you look at them. This metamorphosis is made possible by birefringence, an optical property of certain materials that changes the polarization state of transmitted light. Examples of birefringent materials include ice, calcite crystals, cellophane film, and transparent tape.

Hubble detects protective shield defending a pair of dwarf galaxies

For billions of years, the Milky Way’s largest satellite galaxies—the Large and Small Magellanic Clouds—have followed a perilous journey. Orbiting one another as they are pulled in toward our home galaxy, they have begun to unravel, leaving behind trails of gaseous debris. And yet—to the puzzlement of astronomers—these dwarf galaxies remain intact, with ongoing vigorous star formation.

“A lot of people were struggling to explain how these streams of material could be there,” said Dhanesh Krishnarao, assistant professor at Colorado College. “If this gas was removed from these galaxies, how are they still forming stars?”

With the help of data from NASA’s Hubble Space Telescope and a retired satellite called the Far Ultraviolet Spectroscopic Explorer (FUSE), a team of astronomers led by Krishnarao has finally found the answer: the Magellanic system is surrounded by a corona, a protective shield of hot supercharged gas. This cocoons the two galaxies, preventing their gas supplies from being siphoned off by the Milky Way, and therefore allowing them to continue forming new stars.

Physicists take self-assembly to new level

A team of physicists has created a new way to self-assemble particles—an advance that offers new promise for building complex and innovative materials at the microscopic level.

Self-assembly, introduced in the early 2000s, gives scientists a means to “pre-program” particles, allowing for the building of materials without further human intervention—the microscopic equivalent of Ikea furniture that can assemble itself.

The breakthrough, reported in the journal Nature, centers on emulsions—droplets of oil immersed in water—and their use in the self-assembly of foldamers, which are unique shapes that can be theoretically predicted from the sequence of droplet interactions.

Swimming nanorobots treat deadly pneumonia in mice

Nanoengineers at the University of California San Diego have developed microscopic robots, called microrobots, that can swim around in the lungs, deliver medication and be used to clear up life-threatening cases of bacterial pneumonia.

In mice, the microrobots safely eliminated pneumonia-causing bacteria in the lungs and resulted in 100% survival. By contrast, untreated mice all died within three days after infection.

The results are published Sept. 22 in Nature Materials.

Terahertz light from superconducting stripes

Why do some materials carry electrical currents without any resistance only when cooled to near absolute zero while others do so at comparatively high temperatures? This key question continues to vex scientists studying the phenomenon of superconductivity. Now a team of researchers from Andrea Cavalleri’s group at the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg has provided evidence that electron “stripes” in certain copper-based compounds may lead to a break in the material’s crystal symmetry, which persists even in their superconducting state. Their work has been published in PNAS.

Focusing on a range of cuprates, the team investigated the coexistence and competition of their with other quantum phases. Such interactions are believed to be crucial to the development of high-temperature superconductivity—a process which remains one of the most important unsolved problems in condensed matter physics today.

The researchers exposed several cuprate crystals, grown and characterized at Brookhaven National Labs, to ultrashort laser light pulses. They observed how the materials began to emit a particular type of terahertz (THz) light—a technique known as THz emission spectroscopy.

Astronomers found a new way to hunt for alien worlds

The hunt for alien worlds is more difficult than it may seem. Without the ability to travel through the cosmos, we’re left to look through telescopes and collect data to determine whether other planets lie in wait. Now, though, astronomers say they may have figured out a way to make the search for these alien worlds much easier, and it relies on a technique that looks for debris fields.

Feng Long, a postdoctoral fellow at Harvard and the Smithsonian’s Center for Astrophysics, says she discovered a possible new technique that can make finding alien worlds much easier. Instead of relying on blindly sifting through data, Long looked for material and fields of debris at the Lagrange points. She published a paper on the technique and her findings in The Astrophysical Journal Letters.

The Lagrange points can be thought of as parking places in space. These points are notable because they act as an intersection of the different gravitational fields between celestial structures. Essentially, these points act as a middle ground between gravitational pulls. As such, the pull of gravity from all objects is equal. So, debris from developing alien worlds may congregate here, Long says.

The Perseverance rover is finding more and more organic matter on Mars

NASA’s Perseverance rover is exploring a long-dry river delta on Mars, and it has seen signs that indicate that the region is full of organics – molecules containing carbon that are widely considered to be the building blocks of life.

The rover has taken measurements and samples in an area called Skinner Ridge made of layered sedimentary rocks, some of which contain materials that were most likely transported from hundreds of kilometres away by running water billions of years ago.

“With the samples we’re taking now in this more sedimentary area, we’re of course right at the heart of what we wanted to do to start with,” said NASA science lead Thomas Zurbuchen during a press conference on 15 September. The goal was to look at areas similar to those on Earth that harbour signs of ancient life, he said.

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