Photonic Crystals Bend Light as Though It Were Under the Influence of Gravity

The experimental set-up of beam trajectory in a DPC.
Photo Credit ©K. Kitamura et.al

A collaborative group of researchers has manipulated the behavior of light as if it were under the influence of gravity. The findings, which were published in the journal Physical Review A on September 28, 2023, have far-reaching implications for the world of optics and materials science, and bear significance for the development of 6G communications.

Albert Einstein's theory of relativity has long established that the trajectory of electromagnetic waves--including light and terahertz electromagnetic waves--can be deflected by gravitational fields.

Photonic Crystals Bend Light as Though It Were Under the Influence of Gravity--i.e., pseudogravity--is possible by deforming crystals in the lower normalized energy (or frequency) region.

"We set out to explore whether lattice distortion in photonic crystals can produce pseudogravity effects," said Professor Kyoko Kitamura from Tohoku University's Graduate School of Engineering.

Marine bacteria take a bite at plastic pollution

Plastic waste in the ocean is becoming a pressing issue.
Image Credit: rawpixel

A bacterium that can degrade the common polymer polybutylene succinate (PBS), which naturally biodegrades to only a limited extent in marine environments, could lead to improved ways to recycle this polymer. The bacterium’s potential, and its enzyme molecule that breaks down PBS, was discovered by researchers at Hokkaido University, working with colleagues at the Mitsubishi Chemical Group in Japan. The team published their results in the journal Environmental Microbiology.

PBS is generally regarded as an eco-friendly polymer due to its biodegradability when discarded on land and exposed to the atmosphere. This has led to its increasing use since the early 1990s in industrial plastics, including mulching films, compostable bags and catering packaging. But many discarded plastics eventually find their way into the sea, and unfortunately PBS does not biodegrade well in that environment.

“Plastic pollution in the ocean is a global problem and we need to tackle it by gaining new understanding of plastic behavior in that environment, and new technologies to deal with the pollution,” says Tomoo Sawabe, leader of the research team at Hokkaido University’s Faculty of Fisheries Sciences.

Sexism and poorer parenting: Auckland study suggests a link

Professor Nickola Overall (top left) with researchers Dr Annette Henderson, Dr Rachel Low, Dr Valerie Chang, Dr Caitlin McRae and Dr Nina Waddell.
Photo Credit: Courtesy of University of Auckland

Fathers and mothers who believe men should hold the power and authority in society and the family were less responsive to their children during family interactions, according to University of Auckland research.

The study was the first of its type.

“For decades, sexism has been known to predict negative behaviors toward women, from discrimination to violence,” says lead author Professor Nickola Overall, of Waipapa Taumata Rau, University of Auckland. “Our study suggests the effects flow through to poorer parenting.”

Video-recording family groups in the laboratory, researchers assessed parents’ responsiveness, including warmth, involvement, engagement, and sensitivity toward their children.

The less responsive parents – both mothers and fathers – had disclosed higher levels of “hostile sexism,” an academic term for attitudes favoring male authority and antagonism toward women who challenge men’s social power.

Extinct fish is alive and well

‘Extinct’ houting from the collection of the Natural History Museum London.
Photo Credit: Ymke Winkel

The houting, a fish species that lived in North Sea estuaries and is officially extinct, turns out to be alive and well. Researchers from the University of Amsterdam and the Natural History Museum London extracted DNA from multiple houtings conserved in the museum, up to 250+ years old. Next they compared the DNA of these museum fish with DNA from various currently occurring sibling species. The biologists found hardly any genetic difference between houting and a species called European whitefish. Since this species is still common, houting also isn’t extinct.

In a recent publication in the journal BMC Ecology and Evolution, the researchers describe how they isolated mitochondrial DNA from the fish. They even managed to obtain a small piece of DNA from a dried North Sea houting from 1754 that was used by Linnaeus for the official species description. Next, they used the DNA to create a phylogenetic tree, in which all examined houting (Coregonus oxyrinchus) ended up in the same group as the European whitefish (Coregonus lavaretus).

Thousands of programmable DNA-cutters found in algae, snails, and other organisms

Amoeba proteus with pseudopodia, cytoplasm often with truncated bipyramidal crystals
Image Credit: SmallRex
(CC BY-SA 4.0 DEED)

A diverse set of species, from snails to algae to amoebas, make programmable DNA-cutting enzymes called Fanzors — and a new study from scientists at MIT’s McGovern Institute for Brain Research has identified thousands of them. Fanzors are RNA-guided enzymes that can be programmed to cut DNA at specific sites, much like the bacterial enzymes that power the widely used gene-editing system known as CRISPR. The newly recognized diversity of natural Fanzor enzymes, reported in the journal Science Advances, gives scientists an extensive set of programmable enzymes that might be adapted into new tools for research or medicine.

“RNA-guided biology is what lets you make programmable tools that are really easy to use. So, the more we can find, the better,” says McGovern Fellow Omar Abudayyeh, who led the research with McGovern Fellow Jonathan Gootenberg.

CRISPR, an ancient bacterial defense system, has made it clear how useful RNA-guided enzymes can be when they are adapted for use in the lab. CRISPR-based genome editing tools developed by MIT professor and McGovern investigator Feng Zhang, Abudayyeh, Gootenberg, and others have changed the way scientists modify DNA, accelerating research and enabling the development of many experimental gene therapies.

Females less likely to heal from ACL injuries than males

An analysis of genes expressed by healing rabbit ligaments may lead to a better understanding of ACL injury prevention and treatment in humans, according to Penn State researchers.
Photo Credit: Nicolas Hoizey

Injuries of the anterior cruciate ligament (ACL), located in the knee, are typically thought to be caused by acute traumatic events, such as sudden twists. Led by Penn State researchers, new work analyzing an animal model of ACLs suggests that such injuries can also occur as a result of chronic overuse, specifically due to a reduced ability to repair microtraumas associated with overuse. Importantly, the team said, females also are less able to heal from these microtraumas than males, which may explain why females are two to eight times more likely to tear their ACL ligaments than males.

“ACL tears are one of the most common injuries, affecting more than 200,000 people in the U.S. each year, and women are known to be particularly susceptible,” said principal investigator Spencer Szczesny, associate professor of biomedical engineering and of orthopedics and rehabilitation at Penn State. “While recent research suggests that chronic overuse can lead to ACL injuries, until now, no one had investigated the differential biological response of female and male ACLs to applied force.”

A New Method for Assessing the Microbiome of the Human Gut

A technique called 'bead beating.'
Photo Credit: Courtesy of California Institute of Technology

The gut microbiome—the population and variety of bacteria within the intestine—is thought to influence a number of behavioral and disease traits in humans. Most obviously, it affects intestinal health. Cancer, inflammatory bowel disease, and celiac disease, for example, are all affected by the gut microbiome. But recent research at Caltech and other research centers has identified connections between the gut microbiome and diseases such as Parkinson's disease and multiple sclerosis as well as links between the gut microbiome and the presence of autistic behaviors, anxious behaviors, and a propensity to binge-eat sweets. (Most of this work has been done in the laboratory of Sarkis Mazmanian, Caltech's Luis B. and Nelly Soux Professor of Microbiology, who works mainly on mouse models.)

Looking directly at the human gut and the bacteria that make this space their home is often performed with sequencing—a process that analyzes the DNA sequences that make up each organism. However, this process is difficult in the intestine largely because the amount of microbial DNA in the gut is miniscule in comparison to the amount of host DNA. In intestinal tissue, roughly 99.99 percent of the DNA present is from the host organism; only 0.01 percent is microbial DNA.

However powerful the effects of these microbes, it is hard to understand their role without knowing their composition. Microbiome studies often rely on studies of feces and saliva, but these are quite different from the ecosystem of the gut itself.

New invasive, weedy grasses discovered across Hawaiʻi, some pose major fire risk

Enneapogon cenchroides is the most flammable grass species that Faccenda discovered. It was found in Mākaha.
Photo Credit: Courtesy of University of Hawaiʻi

New species of flammable invasive grasses have been discovered and identified across most Hawaiian islands by a University of Hawaiʻi at Mānoa School of Life Sciences PhD student.

Kevin Faccenda discovered 34 invasive and/or weedy species never before reported in Hawaiʻi during more than 50 days of fieldwork conducted across Kauaʻi, Oʻahu, Maui, Molokaʻi and Hawaiʻi Island over the past year. Six of these species have never been found outside of their native range before, making Hawaiʻi the first place worldwide to experience naturalizations by these species. Faccenda says controlling the spread of these grass species and others is critical to avoid future wildfires, like the one that devastated Lahaina on August 8.

Neutrons see stress in 3D-printed parts, advancing additive manufacturing

The OpeN-AM experimental platform, installed at the VULCAN instrument at ORNL’s Spallation Neutron Source, features a robotic arm that prints layers of molten metal to create complex shapes. This allows scientists to study 3D printed welds microscopically.
Photo Credit: Jill Hemman, ORNL/U.S. Dept. Of Energy

Using neutrons to see the additive manufacturing process at the atomic level, scientists have shown that they can measure strain in a material as it evolves and track how atoms move in response to stress.

“The automotive, aerospace, clean energy and tool-and-die industries — any industry that needs complex and high-performance parts — could use additive manufacturing,” said Alex Plotkowski, materials scientist in ORNL’s Materials Science and Technology Division and the lead scientist of the experiment. Plotkowski and his colleagues reported their findings in Nature Communications.

ORNL scientists have developed OpeN-AM, a 3D printing platform that can measure evolving residual stress during manufacturing using the VULCAN beamline at ORNL’s Spallation Neutron Source, or SNS, a Department of Energy Office of Science user facility. When combined with infrared imaging and computer modeling, this system enables unprecedented insight into material behavior during manufacturing.

Targeting a coronavirus ion channel could yield new Covid-19 drugs

MIT chemists found that the SARS-CoV-2 E protein, which acts as an ion channel, has a broad opening at the bottom when in the closed state and a narrower opening in the open state.
Image Credits: Courtesy of the researchers, MIT News, and iStock
(CC BY-NC-ND 3.0 DEED)

The genome of the SARS-CoV-2 virus encodes 29 proteins, one of which is an ion channel called E. This channel, which transports protons and calcium ions, induces infected cells to launch an inflammatory response that damages tissues and contributes to the symptoms of Covid-19.

MIT chemists have now discovered the structure of the “open” state of this channel, which allows ions to flow through. This structure, combined with the “closed” state structure that was reported by the same lab in 2020, could help scientists figure out what triggers the channel to open and close. These structures could also guide researchers in developing antiviral drugs that block the channel and help prevent inflammation.

“The E channel is an antiviral drug target. If you can stop the channel from sending calcium into the cytoplasm, then you have a way to reduce the cytotoxic effects of the virus,” says Mei Hong, an MIT professor of chemistry and the senior author of the study.

MIT postdoc Joao Medeiros-Silva is the lead author of the study, which appears today in Science Advances. MIT postdocs Aurelio Dregni and Pu Duan and graduate student Noah Somberg are also authors of the paper.