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There’s a great future in plastics.

A new kind of plastic can, when exposed to the right chemicals, break down into the same basic building blocks that it came from and be rebuilt again and again. The recyclable material is more durable than previous attempts to create reusable plastics, researchers report inthe April 27 Science.

Designing plastics that can be easily reused is one line of attack against the global plastic waste problem. Only about 10 percent of plastic ever made gets recycled, according to a 2017 study in Science Advances. But the material is so cheap and useful that hundreds of millions of tons of it keeps getting churned out each year.
A major impediment to plastic recycling is that most plastics degrade into molecules that aren’t immediately useful. Transforming those molecules back into plastic or into some other product requires many chemical reactions, which makes the recycling process less efficient. And while biodegradable plastics have become popular in recent years, they break down only if the right microbes are present. More often than not, these plastics end up lingering in landfills or floating in the ocean. Creating plastics that could be broken down into their building blocks and reused without additional processing and purifying could help reduce the pollution buildup.

But designing such a plastic polymer is a balancing act, says Michael Shaver, a polymer chemist at the University of Edinburgh who wasn’t part of the study. Polymers are long chains of small molecules, called monomers, that link together like beads on a string. Monomers that need extreme temperatures or too much chemical coaxing to join up into polymers might not be practical building blocks. And resulting polymers need to be stable up to a high enough temperature that, say, pouring hot coffee into a cup made of them won’t destabilize the chains and make the plastic melt into a sticky puddle.
Polymer chemist Jianbo Zhu and his colleagues at Colorado State University in Fort Collins set out to solve this challenge. The team had had some luck in the past creating a polymer that could be broken down into its starting molecules. But the resulting plastics created by their lab and others on the same track were too soft and temperature-sensitive to have much practical use.
This time, Zhu and his colleagues modified one of their previous creations, a small ringed molecule, by adding another ring in a way that braced the molecule into a particular conformation. That rigidity helped the monomers quickly link together at room temperature into polymer chains that are heat-stable.
Then, when exposed to certain mild chemicals or high enough heat, the polymers degraded back into monomers. The researchers were able to repeat this cycle several times, showing that, in theory, the polymer could be infinitely recyclable.

While each monomer is locked into a particular conformation, not all of them have the same shape even though they’re made from the same chemical recipe. Mixing two different conformations of monomers created an even stronger plastic, says Zhu.

“This is probably the best system out there,” Shaver says.

Still, it’s not perfect yet: Zhu and his colleagues plan to tinker with the monomer design more in the future to make the resulting plastic a bit less brittle. Eventually, they hope to commercialize the product.

As opioid-related deaths rise in the United States, so has the role of synthetic opioids — primarily illicit fentanyl, mixed into heroin or made into counterfeit pills (SN Online: 3/29/18). In 2016, synthetics surged past prescription opioids and were involved in 19,413 deaths, compared with 17,087 deaths involving prescription opioids, researchers report May 1 in JAMA. The study is based on data from the National Vital Statistic System’s record of all U.S. deaths.

“Synthetic opioids are much deadlier than prescription opioids,” says emergency physician Leana Wen, Health Commissioner of Baltimore, who was not involved in the study. Fentanyl, for example, is about 50 to 100 times more potent than morphine. The illicit origins of many synthetic opioids make the public health response more difficult, she says. “We can track prescriptions; it’s much harder to track illegally trafficked drugs.”

Clearwing moths may not look all that dangerous, despite having largely see-through wings like bees and wasps. But some fly like fierce insects best left well alone.

Four clearwing species from Southeast Asian rainforests aren’t perfect mimics of local bees and wasps. Yet the resemblance looked much stronger when entomologist Marta Skowron Volponi of the University of Gdansk in Poland and her husband, nature filmmaker Paolo Volponi, spent days at a time poised with a video camera on riverbanks to capture the flight patterns. Four clearwing species occasionally showed up, including a shaggy Aschistophleps that turned out to be a species new to science.

That newly named A. argentifasciata and two other species flew in slow, zigzaggy paths that resembled the meanderings of local stingless bees. (This kind of bee is not great for snacking birds because it bites fiercely.) Another clearwing moth flew distinctly faster with broader turning sweeps instead of zigzags, much like a wasp.

Behaving like something that stings or bites may be an advantage for moths that forgo the cover of night and fly in daylight with its abundance of hungry birds and other predators that hunt by sight. Even imperfect body mimics get convincing in the air, Skowron Volponi and her colleagues report May 2 in Biology Letters.

Jupiter’s icy moon Europa may have been spitting into space for at least 20 years. Analyzing old Galileo mission data suggests that the NASA spacecraft flew through a plume of water vapor from the moon during a 1997 flyby, researchers report May 14 in Nature Astronomy.

“We now have very compelling support for the idea that Europa does possess plumes,” says study coau
Whether the moon, Jupiter’s fourth largest, has such geysers has been a lingering mystery. One of the most tantalizing results from Galileo, which orbited Jupiter from 1995 to 2003, was evidence that Europa harbors a deep ocean of liquid water beneath an icy shell. Then in 2012, data from the Hubble Space Telescope revealed high concentrations of charged hydrogen and oxygen atoms, or ions, over Europa’s southern hemisphere, a potential sign of water vapor escaping into space (SN: 1/25/14, p. 6).

The putative plumes have played peekaboo ever since (SN Online: 1/11/18), continuing to intrigue astronomers hoping to search the moon’s water for signs of life.

Jia and colleagues examined data from Galileo’s closest Europa flyby, which brought the probe within 206 kilometers of the moon’s surface. Over one spot near the equator, the spacecraft detected sudden changes in its magnetic field and plasma instruments. Using up-to-date computer simulations, the team showed that these changes are best explained by Galileo flying through an active plume. Radiation from Jupiter’s magnetic field would have split water molecules into oxygen and hydrogen ions, and those particles, in turn, would have changed the direction of the magnetic field and the density of plasma within the plume. That spot is also near where Hubble picked up a second sign of escaping water vapor
in 2014 (SN Online: 9/26/16) .
Galileo found no other signs of plumes during its 10 other Europa flybys, which were farther away from the moon. That suggests that any plumes are relatively small, extending not much higher than 200 kilometers above the surface. It’s also unclear if Europa plumes would be spewing constantly or be turning on and off.

Jia is working on magnetic field and plasma instruments for two future missions to Jupiter and its moons: the 2022 European JUICE mission and NASA’s Europa Clipper spacecraft, also planned for the early 2020s. The Clipper spacecraft will make much lower flybys over Europa, skimming as low as 25 kilometers above the surface. The new Galileo results should help in planning those flight paths, he says.

NASA will host a live discussion of these findings at 1:00 p.m. EDT on May 14. You can watch on various platforms, including NASA Television, Facebook Live and YouTube.

Planetary scientist Cynthia Phillips of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who worked on Galileo as a graduate student but was not involved in the new analysis, says it’s exciting that scientists are using new tools on the old mission data.

“During Galileo, we’d always known there was something weird during this flyby,” she says. But she is still holding out for visual confirmation of the plumes. “Pictures, or it didn’t happen.”

Sluggish memories might be captured via RNA. The molecule, when taken from one sea slug and injected into another, appeared to transfer a rudimentary memory between the two, a new study suggests.

Most neuroscientists believe long-term memories are stored by strengthening connections between nerve cells in the brain (SN: 2/3/18, p. 22). But these results, reported May 14 in eNeuro, buoy a competing argument: that some types of RNA molecules, and not linkages between nerve cells, are key to long-term memory storage.
“It’s a very controversial idea,” admits study coauthor David Glanzman, a neuroscientist at UCLA.

When poked or prodded, some sea slugs (Aplysia californica) will reflexively pull their siphon, a water-filtering appendage, into their bodies. Using electric shocks, Glanzman and his colleagues sensitized sea slugs to have a longer-lasting siphon-withdrawal response — a very basic form of memory. The team extracted RNA from those slugs and injected it into slugs that hadn’t been sensitized. These critters then showed the same long-lasting response to touch as their shocked companions.

RNA molecules come in a variety of flavors that carry out specialized jobs, so it’s not yet clear what kind of RNA may be responsible for the effect, Glanzman says. But he suspects that it’s one of the handful of RNA varieties that don’t carry instructions to make proteins, the typical job of most RNA. (Called noncoding RNAs, these molecules are often involved in manipulating genes’ activity.)

But even the few scientists who question whether the strength of nerve cell connections is the key to long-term memory storage don’t necessarily buy Glanzman’s ideas. The fact that untrained slugs become more sensitive to touch after RNA injection is “amazing,” says biochemist Tomás Ryan of Trinity College Dublin, who wasn’t part of the study. “But it doesn’t go far enough to say that the memory has been transferred.”

After a giant asteroid hit Earth about 66 million years ago, the planet’s climate went on a roller coaster ride.

The space rock’s impact set off tsunamis and wildfires before climate-chilling clouds of sulfur gas engulfed the planet for decades, wiping out most life (SN: 11/25/17, p. 14). As these clouds dissipated, billions of tons of carbon dioxide, which spewed into the atmosphere when the asteroid hit, fueled roughly 100,000 years of global warming, new data suggest. Analyzing fossilized fish bits hints that the influx of the greenhouse gas raised the temperature of the ocean on average by 5 degrees Celsius, scientists report online May 24 in Science.
It’s not surprising that the climate heated up after the collision, which left a 200-kilometer-wide crater centered around what’s now Chicxulub, Mexico, says Johan Vellekoop, a geologist at KU Leuven in Belgium. But finding evidence to back up the warming claim has been challenging.

A common way to estimate past temperatures on Earth is to measure the proportion of heavier to lighter forms of oxygen in the carbonate shells left behind by dead invertebrates. Animals incorporate different oxygen forms into shells, teeth and bones at different rates depending on temperature. But carbonate fossils from around the time of the impact aren’t well enough preserved to be a reliable thermometer.

Instead, paleogeologist Ken MacLeod of the University of Missouri in Columbia and colleagues analyzed those same types of oxygen ratios in a crushed jumble of fish bones, teeth and scales — a different way to measure past temperatures. The team collected sediment samples from a section of rock in what’s now El Kef, Tunisia, that records the transition between the periods before and after the impact in its layers. (Samples from 2 meters of rock laid down before the impact and 6.6 meters laid down after the strike recorded almost 250,000 years of geologic history.) Back in the lab, the researchers spent hours peering through microscopes to sort out glassy, amber fish teeth and mineralized scales and measure the oxygen content within them.
The ratio of heavier oxygen to lighter decreased by about 1 percent in the fish bits collected after the impact compared with those pieces from before the impact, the team found. That change translates to an increase in seawater temperature of about 5 degrees Celsius — a substantial amount.
The elevated temperatures persisted for about 100,000 years before the planet cooled down again, an analysis of fish debris collected from different levels of rock showed. While the study looked only at ocean temperature, air temperature would probably reflect that increase, too, MacLeod says.

“It’s a pretty robust result,” says Clay Tabor, a climate scientist at the University of Connecticut in Hartford. But getting similar results from sites elsewhere in the world would boost the case that this was a global effect and not a local fluke, he says.

The story is far from over, MacLeod agrees. It’s not clear how long after the impact the warming began, for instance. His team hopes to analyze fish debris from other sites that might reveal finer-scale changes in temperature.

Nothing against trees. But maybe it’s better not to get too dependent on them if you want to survive a big flaming space object crashing into Earth.

The asteroid impact that caused a mass extinction 66 million years probably also triggered the collapse of forests worldwide, a new investigation of the plant fossil record concludes. Needing trees and extensive plant cover for nesting or food could have been a fatal drawback for winged dinosaurs, including some ancient birds. Reconstructing the ecology of ancient birds suggests that modern fowl descended from species that survived because they could live on the ground, an international research team proposes in the June 4 Current Biology.
“You probably would have died anyway regardless of habitat,” says study coauthor Daniel Field, an evolutionary paleobiologist at the University of Bath in England. “But if you could get along on the ground, you at least had a shot at surviving across this devastated landscape.”

The shock wave from the strike probably flattened trees within a radius of 1,500 kilometers, Field says. Wildfires ignited around the planet and then came the acid rain. Clouds of ash and dust may have darkened the sky for several years, and researchers suspect that photosynthesis waned. Yet some lucky birds, but no other dinosaurs, survived the hellscape.

For clues to what made a survivor, researchers turned to fossilized pollen from before and after the fiery impact. Abundant kinds of flower-bearing and cone-bearing plants left pollen just before the asteroid hit and again starting about a thousand years afterward. In between those times of diversity, however, ferns dominated, the team notes. A kind of “disaster flora,” ferns (making spores instead of flowers and seeds) do well at recolonizing land. Seed plants, however, weren’t thriving.

Analyzing evolutionary histories of modern birds supports the idea of tree dependence as a vulnerability for the earliest fowl, the researchers say. Specialists in bird evolution now generally agree on the lowest, oldest branches of the bird family tree, Field says. The bottommost one, for instance, includes such modern species as ground-dwelling ostriches and smaller, flight-capable birds called tinamous, which might be more like the ancient birds that dodged extinction.
Working backward along these low branches, researchers used fossils and known bird traits to reconstruct the most likely lifestyles of the earliest survivors. These probably weren’t tree-dependent birds, the researchers conclude.

The glory days of dinosaurs had had plenty of flying tree-dwellers. So far, paleontologists have identified at least 80 kinds of what are called “opposite birds,” the Enantiornithes (SN: 2/4/17, p. 26). “If you saw one flying around today, you’d say, ‘Well, that’s a bird,’ ” Field explains. Their feet looked like those of birds that perch on tree limbs, so he’s not surprised that a fossil of an opposite bird from this probably arboreal group has never been found in rock formed after the dino doomsday.

What did happen, however, was that when trees and forests came back after the disaster, birds quickly evolved arboreal lifestyles, the team says.

Many people don’t realize that birds almost died off during the mass extinction, too, says paleontologist Stephen Brusatte of the University of Edinburgh who has studied bird evolution but was not involved in the new study. What let the few survivors squeak through, he says, has been a mystery for a long time. The whole scenario of a ground-dweller’s advantage and then a return to the trees “makes a lot of intuitive sense.”

The veteran Opportunity rover isn’t dead yet. Currently, the craft is in a deep sleep to ride out a massive Martian dust storm, NASA officials said in a briefing on June 13. The rover may wake itself up when the storm ends.

Opportunity is enveloped in a vast dust storm that grew from a small patch spotted on May 30 to cover a quarter of the planet by June 12 (SN Online: 6/11/18). Too little sunlight is reaching the rover’s solar panels, so Opportunity is in low-power mode — just barely enough to run the rover’s internal clock — until its batteries can charge again. The team hasn’t heard from Opportunity since June 10, and no transmissions are expected until the storm clears.
The Martian summer is just beginning, so the rover should stay warm enough to survive for a long time in this mode, said Opportunity’s project manager John Callas, a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

“When the skies clear and the rover begins to power up, it should be able to communicate with us,” he said.
That’s not to say the team isn’t worried. Based on past storms, the wait could be anywhere from a few weeks to a few months.
“It’s like you have a loved one in a coma in the hospital,” Callas said. “You have the doctors telling you that, ‘OK, you just have to give it time and she’ll wake up,’… but if it’s your 97-year-old grandmother, you’re going to be very concerned. And so we are. By no means are we out of the woods here.”

Opportunity landed on Mars on January 25, 2004, and was supposed to last 90 Martian days. It has now spent 5,113 Martian days driving more than 45 kilometers.

About 99 million years ago, tiny frogs hopped through a wet, tropical forest — and an unlucky few ran afoul of some tree sap. Four newly described frog fossils, preserved in amber, offer the earliest direct evidence of ancient frogs living in a humid tropical clime — just as many modern amphibians do.

None of the frog fossils is complete, making it difficult to place the frogs within their family tree: One has a partial skull and another a froggy outline, although CT scanning revealed no remaining skeletal material inside the impression. So researchers dubbed all four fossils Electrorana limoae (electrum for “amber” and rana for “frog”) in a study published June 14 in Scientific Reports. Anatomy-wise, the ancient frogs most resemble a modern group that includes fire-bellied toads.

The fossil record contains relatively few frogs, despite the amphibians’ more than 200-million-year history. The frog fossils that do exist suggest that frogs have looked distinctly — well, froggy — for hundreds of millions of years, says study coauthor David Blackburn, an amphibian biologist at the Florida Museum of Natural History in Gainesville. “The aspects that make them diverse are not their skeletons, it’s their ecologies, natural histories, reproductive modes. Things that are really hard to find in the fossil record.”

That’s what makes the amber specimens so interesting: The chunks also contain preserved spiders, velvet worms and bamboo — all pointing to a tropical environment. Such paleoecological evidence offers scientists a rare glimpse into the life and times of tropical frogs of old.

Making day-to-day activities more vigorous for a few minutes — such as briefly stepping up the pace of a walk — could offer people who don’t exercise some of the health benefits that exercisers enjoy.

That’s according to a new study of roughly 25,000 adults who reported no exercise in their free time. Those who incorporated three one- to two-minute bursts of intense activity per day saw a nearly a 40 percent drop in the risk of death from any cause compared with those whose days didn’t include such activity. The risk of death from cancer also fell by nearly 40 percent, and the risk of death from cardiovascular disease dropped almost 50 percent, researchers report online December 8 in Nature Medicine.

In a comparison with around 62,000 people who exercised regularly, including runners, gym-goers and recreational cyclists, the mortality risk reduction was similar.

“This study adds to other literature showing that even short amounts of activity are beneficial,” says Lisa Cadmus-Bertram, a physical activity epidemiologist at the University of Wisconsin–Madison, who was not involved in the research. “So many people are daunted by feeling that they don’t have the time, money, motivation, transportation, etc. to go to a gym regularly or work out for long periods of time,” she says. “The message we can take is that it is absolutely worth doing what you can.”

Emmanuel Stamatakis, an epidemiologist at the University of Sydney, and his colleagues analyzed a subset of records from the UK Biobank, a biomedical database containing health information on half a million people in the United Kingdom. The study’s non-exercising participants — more than half of whom were women and were 62 years old on average — had worn movement-tracking devices for a week.

Over an average seven years of follow-up, for those whose days included three to four bursts of activity, the mortality rate was 4.2 deaths from any cause per 1,000 people for one year. For those with no activity bursts, it was 10.4 deaths per 1,000 people for one year.

The researchers were looking for bursts of vigorous activity that met a definition determined in a laboratory study, including reaching at least 77 percent of maximum heart rate and at least 64 percent of maximum oxygen consumption. In real life, the signs that someone has reached the needed intensity level are “an increase in heart rate and feeling out of breath” in the first 15 to 30 seconds of an activity, Stamatakis says.

Regular daily activities offer several opportunities for these vigorous bursts, he says. “The simplest one is maximizing walking pace for a minute or two during any regular walk.” Other options, he says, include carrying grocery bags to the car or taking the stairs. “The largest population health gains will be realized by finding ways to get the least physically active people to move a little more.”