Used plastic bottles and textiles pose an increasing problem for landfills worldwide. Researchers say nearly a hundred million metric tons of polyethylene terephthalate (PET), also known as microplastics, are produced globally each year — with a fraction of that number being recycled — making it one of the largest sources of plastic waste.

“One way we can manage plastic waste is through integrating it into geotechnical construction,” explains doctoral student Alok Chandra. “By finding new ways to use these discarded plastics, we can divert them from landfills and use them to stabilize cover materials within landfills.”

Chandra and his supervisor, UBCO Engineering Professor Dr. Sumi Siddiqua, have developed a new method of incorporating PET waste into clay soil stabilization.

“Due to its nontoxicity, low biodegradability and accessibility, it shows considerable potential for use in landfill designs. However, a considerable amount of research is still required,” says Dr. Siddiqua. “This not only solves the solid waste problem but also increases the economic value of waste and encourages its re-circulation back from already polluted lands and oceans.”

The study suggests the reused material strengthens the soil and serves as a water-resistant layer that will keep pollutants such as lead from escaping the landfill.

“Our results show great potential, but there is still some work to be done before we will integrate the PET waste into landfill soil stabilization management,” says Chandra.

The research is published in the journal Waste Management and funded by the Natural Sciences and Engineering Research Council of Canada Discovery Grants Program.

While more research needs to be done, they said, the advance in single atom catalysis has the potential to lower exhaust emissions of methane, one of the worst greenhouse gases, which traps heat at about 25 times the rate of carbon dioxide.

Researchers from the Department of Energy’s SLAC National Accelerator Laboratory and Washington State University showed that the catalyst removed methane from engine exhaust at both the lower temperatures where engines start up and the higher temperatures where they operate most efficiently, but where catalysts often break down.

“It’s almost a self-modulating process which miraculously overcomes the challenges that people have been fighting — low temperature inactivity and high temperature instability,” said Yong Wang, Regents Professor in WSU’s Gene and Linda Voiland School of Chemical Engineering and Bioengineering and one of four lead authors on the paper.

A growing source of methane pollution

Engines that run on natural gas power 30 million to 40 million vehicles worldwide and are popular in Europe and Asia. The natural gas industry also uses them to run compressors that pump gas to people’s homes. They are generally considered cleaner than gasoline or diesel engines, creating less carbon and particulate pollution.

However, when natural-gas engines start up, they emit unburnt, heat-trapping methane because their catalytic converters don’t work well at low temperatures. Today’s catalysts for methane removal are either inefficient at lower exhaust temperatures or they severely degrade at higher temperatures.

“There’s a big drive towards using natural gas, but when you use it for combustion engines, there will always be unburnt natural gas from the exhaust, and you have to find a way to remove that. If not, you cause more severe global warming,” said co-author Frank Abild-Pedersen, a SLAC staff scientist and co-director of the lab’s SUNCAT Center for Interface Science and Catalysis, which is run jointly with Stanford University. “If you can remove 90% of the methane from the exhaust and keep the reaction stable, that’s tremendous.”

A catalyst with single atoms of the chemically active metal dispersed on a support also uses every atom of the expensive and precious metal, Wang added.

“If you can make them more reactive,” he said, “that’s the icing on the cake.”

Unexpected help from a fellow pollutant

In their work, the researchers showed that their catalyst made from single palladium atoms on a cerium oxide support efficiently removed methane from engine exhaust, even when the engine was just starting.

They also found that trace amounts of carbon monoxide that are always present in engine exhaust played a key role in dynamically forming active sites for the reaction at room temperature. The carbon monoxide helped the single atoms of palladium migrate to form two- or three-atom clusters that efficiently break apart the methane molecules at low temperatures.

Then, as the exhaust temperatures rose, the clusters broke up into single atoms and redispersed, so that the catalyst was thermally stable. This reversible process enabled the catalyst to work effectively and used every palladium atom the entire time the engine was running — including when it started cold.

“We were really able to find a way to keep the supported palladium catalyst stable and highly active and, because of the diverse expertise across the team, to understand why this was occurring,” said SLAC staff scientist Christopher Tassone.

The researchers are working to further advance the catalyst technology. They would like to better understand why palladium behaves in one way while other precious metals such as platinum act differently.

The research has a way to go before it will be put inside a car, but the researchers are collaborating with industry partners as well as with DOE’s Pacific Northwest National Laboratory to move the work closer to commercialization.

Along with Wang, Abild-Pedersen, and Tassone, Dong Jiang, senior research associate in WSU’s Voiland School, also led the work. The work was funded by the DOE Office of Science, and included research carried out at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), Argonne National Laboratory’s Advanced Photon Source (APS) and the National Energy Research Scientific Computing Center (NERSC), which are all DOE Office of Science user facilities.

What comes to your mind when you think of biology? Animals, plants, theoretical computer models? The last one, you might not associate with it right away, although it is a major part of biological research. It is precisely these calculations that help to understand complex biological phenomena, down to the most concealed details. ISTA Professor Edouard Hannezo applies them to understand physical principles in biological systems. His group’s latest work gives novel insights into how cells are moving and communicating inside living tissue.

During his PhD, Daniel Boocock, along with Hannezo and long-term collaborator Tsuyoshi Hirashima from the National University of Singapore, developed a detailed new theoretical model, which is published today in the journal PRX Life. It allows a better understanding of long-range cell-cell communication and describes both the complex mechanical forces the cells apply to each other and their biochemical activity.

Cells communicate in waves

“Let’s say you have a Petri dish that is covered with cells — a monolayer. They appear to just sit there. But the truth is they move, they swirl, and they spontaneously make chaotic behaviors,” Hannezo explains.

Similar to a dense crowd at a concert, if one cell pulls on one side, another cell senses the action and can react by either going in the same direction or pulling the opposite way. Information can then propagate and travel in waves — waves that are visible under a microscope. “Cells not only sense mechanical forces but also their chemical environment — forces and biochemical signals cells are exerting on each other,” Hannezo continues. “Their communication is an interplay of biochemical activity, physical behavior, and motion; however, the extent of each mode of communication and how such mechanochemical interplays function in living tissues has been elusive until now.”

Predicting movement patterns

Driven by the wave visuals, the scientists’ goal was to establish a theoretical follow-up model that would validate their previous theory on how cells move from one region to the next. Daniel Boocock explains, “In our earlier work, we wanted to uncover the biophysical origin of the waves and whether they play a role in organizing collective cell migration. However, we hadn’t considered the liquid-solid transition of the tissue, the noise inherent in the system, or the detailed structure of the waves in 2D.”

Their latest computer model pays attention to cell motility and material properties of the tissue. With it, Boocock and Hannezo found how cells communicate mechanically and chemically and how they move. They were able to replicate the phenomena observed in Petri dishes, verifying a theoretical explanation of cell communication based on physical laws.

Testing the theory

For experimental proof, Boocock and Hannezo collaborated with biophysicist Tsuyoshi Hirashima. To rigorously test whether the new model is applicable to real biological systems, scientists used 2D monolayers of MDCK cells — specific mammalian kidney cells — that are a classical in vitro-model for such research. “If we inhibited a chemical signaling pathway that allows cells to sense and generate forces, the cells stopped moving and no communication waves spread,” Hannezo explains. “With our theory, we can easily change different components of the complex system and determine how the dynamics of the tissue adapt.”

What’s next?

Cellular tissue resembles liquid crystals in some ways: it flows like a liquid but is arranged like a crystal. Boocock adds: “In particular, the liquid crystal-like behavior of biological tissue has only been studied independently of mechanochemical waves.” An extension to 3D tissues or monolayers with complex shapes, just as in living organisms, is one possible future avenue of investigation. The researchers have also begun to optimize the model with regard to wound healing. Where parameters improve the flow of information, healing has been accelerated — in computer simulations. Hannezo adds enthusiastically, “What’s really interesting is how well our model would work for wound healing in cells within living organisms.”

Organic farming is better for biodiversity than conventional farming, which relies heavily on substances such as pesticides, herbicides and fertilisers.

However, little is known about how wildlife is affected by the transition period when a farm goes organic.

The new study, led by the universities of Bristol, Göttingen and Exeter, assessed the effects of organic farming by monitoring insect-eating bats at citrus orchards in Cyprus.

Activity of three of the four species included in the study was significantly lower at farms in the transition period, compared to conventional farms.

However, activity increased on established organic farms — suggesting a “time-lag” before the organic biodiversity boost for the most abundant bat species.

“We were surprised by our results — we expected the transition to organic farming to bring positive effects from the start,” said Penelope Fialas, from the University of Exeter.

“We can’t be certain why bats are negatively affected, but previous research suggests soil can suffer — with knock-on effects for other wildlife — when fertilisers, pesticides and other aspects of conventional farming stop.

“The soil and the wider ecosystem may take time to recover.”

Fialas added: “Our findings suggest the transition to organic farming should be managed carefully, to limit any negative effects on biodiversity.

“For example, neighbouring farms could avoid simultaneous transitions, allowing wildlife to find alternative habitats nearby while each farm switches its methods.”

Gareth Jones, from the University of Bristol, said: “We’ve long known that organic farms often harbour higher biodiversity than otherwise similar conventional farms.

“The transition to organic farming has been little studied, however, and determining if the detrimental effects during transition observed here hold for other animals and plants would be an interesting future research project.”

The study examined 22 matched pairs of citrus orchards, comparing bat activity at certified organic farms with conventional farms, and organic-transition farms with conventional farms.

The bat species included in the study were: Kuhl’s pipistrelle (P. kuhlii), Savi’s pipistrelle (H. savii), common bent-wing (M. schreibersii) and common pipistrelle (P. pipistrellus).

The findings showed:

• Activity of Savi’s pipistrelles was three times lower — and activity of Kuhl’s pipistrelles and common bent-wings was twice as low — on organic-transitional farms compared to conventional farms.
• Activity of Kuhl’s pipistrelles was twice as high on organic farms compared to conventional farms.
• Activity of Kuhl’s pipistrelles and Savi’s pipistrelles was higher or organic farms than on organic-transition farms (by threefold and twofold respectively).
• The presence of “semi-natural” areas surrounding the farms did not affect these differences.

The study was partially funded by the University of Göttingen.

“Until now, there have been rather basic studies describing the formation of plastiglomerates. With our results, we have shown for the first time how plastiglomerate differs from other plastic waste and can make better statements about its environmental impact,” says first author Dr Amanda Utami, who works as a scientist at Indonesia’s largest science organization (BRIN, Badan Riset dan Inovasi Nasional) and came to Kiel on a three-month fellowship. The research work was made possible by funding from the German Academic Exchange Service (DAAD) and cooperation between BRIN and scientists in the Kiel Marine Science (KMS) priority research area at Kiel University.

New insights through international cooperation

If plastic waste is burnt directly on the beach, this melting and burning process produces the plastiglomerate “rock,” in whose plastic matrix the carbon chains are degraded. This chemically degraded plastic weathers more rapidly into microplastics through exposure to wind, waves and sediment grains on the beach. The incomplete combustion process releases new pollutants from the plastic that first settle on the plastic and are then released into the environment. These contaminants often have higher ecotoxicological relevance than the parent plastic, are potentially bioavailable, and thus can be introduced and enriched in the food chain.

Scientist Utami collected a total of 25 field samples from beaches on Panjang Island on the western side of the Indonesian island of Java and analyzed them in the laboratory together with researchers from Kiel University. One of them is Dr Lars Reuning, Utami’s scientific host in Kiel and second author of the study: “Our analyses show that Plastiglomerates are contaminated with organic pollutants. Even though further results on bioaccumulation are still pending, they can be classified as potentially carcinogenic to humans.” Reuning is a member of the Paleontology Research Group at the Institute of Geosciences at Kiel University. The working group, led by Professor Miriam Pfeiffer, is also involved in the German Research Foundation’s (DFG) Earth Science Priority Program 2299 “Tropical Climate Variability and Coral Reefs.”

Chemical investigations of pollutants in the Kiel laboratory

The researchers first differentiated the plastiglomerate samples according to optical criteria into less strongly as well as more strongly melted or burned samples and extracted volatile pollutants with the help of solvents. These analyses, which were carried out in Professor Lorenz Schwark’s Organic Geochemistry Group at the Institute of Geosciences, revealed, for example, contamination with polycyclic aromatic hydrocarbons (PAHs) and phthalates, which are used as plasticizers for plastics. Experts consider both classes of substances to have a high potential for causing cancer.

The research team also used physicochemical methods and comparison with databases to characterize the nature of polymers such as polypropylene (PP) or polyethylene (PE) or their mixtures. They conducted measurements using Fourier transform infrared spectroscopy (FTIR) in the working group of Professor Gernot Friedrichs at the Institute of Physical Chemistry at Kiel University to investigate the degree of weathering. Outcome: Areas that were already visibly more exposed to the burning process also showed a greater degree of weathering and oxidation.

Numerous effects on coastal ecosystems possible

“To better assess environmental damage, we are currently researching the exact composition of the organic pollutants associated with the plastic, such as organophosphorus compounds,” says geochemist Schwark. Also of interest is the tendency of the plastiglomerates to decay easily. “Normally, photo-oxidation by UV light affects the top layer of plastics. But thermo-oxidation by burning the plastic waste significantly alters the internal structures of the material as well,” says geoscientist Reuning.

In the future, numerous coastal ecosystems of tropical waters off Indonesia as well as worldwide will be affected by Plastiglomerates. Studies already show that organic pollutants are also transferred to corals or other marine organisms and can thus have a negative impact on ocean health. Further studies are therefore also looking at other ecosystems such as seagrass beds, mangroves or organisms living in the sediment.

“Compared to normal plastic waste, the unique properties of Plastiglomerates require a specific form of coastal management,” Utami sums up. “If trash from urban areas on tropical beaches were better disposed of and managed, a serious problem could be prevented.”

Experiments have shown that microwaving plastic baby food containers available on the shelves of U.S. stores can release huge numbers of plastic particles — in some cases, more than 2 billion nanoplastics and 4 million microplastics for every square centimeter of container.

Though the health effects of consuming micro- and nanoplastics remain unclear, the Nebraska team further found that three-quarters of cultured embryonic kidney cells had died after two days of being introduced to those same particles. A 2022 report from the World Health Organization recommended limiting exposure to such particles.

“It is really important to know how many micro- and nanoplastics we are taking in,” said Kazi Albab Hussain, the study’s lead author and a doctoral student in civil and environmental engineering at the University of Nebraska-Lincoln. “When we eat specific foods, we are generally informed or have an idea about their caloric content, sugar levels, other nutrients. I believe it’s equally important that we are aware of the number of plastic particles present in our food.

“Just as we understand the impact of calories and nutrients on our health, knowing the extent of plastic particle ingestion is crucial in understanding the potential harm they may cause. Many studies, including ours, are demonstrating that the toxicity of micro- and nanoplastics is highly linked to the level of exposure.”

The team embarked on its study in 2021, the same year that Hussain became a father. While prior research had investigated the release of plastic particles from baby bottles, the team realized that no studies had examined the sorts of plastic containers and pouches that Hussain found himself shopping for, and that millions of other parents regularly do, too.

Hussain and his colleagues decided to conduct experiments with two baby food containers made from polypropylene and a reusable pouch made of polyethylene, both plastics approved by the U.S. Food and Drug Administration. In one experiment, the researchers filled the containers with either deionized water or 3% acetic acid — the latter intended to simulate dairy products, fruits, vegetables and other relatively acidic consumables — then heated them at full power for three minutes in a 1,000-watt microwave. Afterward, they analyzed the liquids for evidence of micro- and nanoplastics: the micro being particles at least 1/1,000th of a millimeter in diameter, the nano any particles smaller.

The actual number of each particle released by the microwaving depended on multiple factors, including the plastic container and the liquid within it. But based on a model that factored in particle release, body weight, and per-capita ingestion of various food and drink, the team estimated that infants drinking products with microwaved water and toddlers consuming microwaved dairy products are taking in the greatest relative concentrations of plastic. Experiments designed to simulate the refrigeration and room-temperature storage of food or drink over a six-month span also suggested that both could lead to the release of micro- and nanoplastics.

“For my baby, I was unable to completely avoid the use of plastic,” Hussain said. “But I was able to avoid those (scenarios) which were causing more of the release of micro- and nanoplastics. People also deserve to know those, and they should choose wisely.”

With the help of Svetlana Romanova from the University of Nebraska Medical Center, the team then cultured and exposed embryonic kidney cells to the actual plastic particles released from the containers — a first, as far as Hussain can tell. Rather than introduce just the number of particles released by one container, the researchers instead exposed the cells to particle concentrations that infants and toddlers might accumulate over days or from multiple sources.

After two days, just 23% of kidney cells exposed to the highest concentrations had managed to survive — a much higher mortality rate than that observed in earlier studies of micro- and nanoplastic toxicity. The team suspects that kidney cells might be more susceptible to the particles than are other cell types examined in prior research. But those earlier studies also tended to examine the effects of larger polypropylene particles, some of them potentially too large to penetrate cells. If so, the Hussain-led study could prove especially sobering: Regardless of its experimental conditions, the Husker team found that polypropylene containers and polyethylene pouches generally release about 1,000 times more nanoplastics than microplastics.

The question of cell infiltration is just one among many that will require answers, Hussain said, before determining the true risks of consuming micro- and nanoplastics. But to the extent that they do pose a health threat — and that plastics remain a go-to for baby food storage — parents would have a vested interest in seeing that the companies manufacturing plastic containers seek out viable alternatives, he said.

“We need to find the polymers which release fewer (particles),” Hussain said. “Probably, researchers will be able to develop plastics that do not release any micro- or nanoplastics — or, if they do, the release would be negligible.

“I am hopeful that a day will come when these products display labels that read ‘microplastics-free’ or ‘nanoplastics-free.'”

The latter examples are so-called “regional endotherms” and are all fast swimming, apex predators at the top of the food chain. Scientists have long reasoned that their ability to keep warm helped with this athletic predatory lifestyle, and that evolution had shaped their physiology to match their requirements.

However, an international team of researchers led by those from Trinity College Dublin, has now shown that gentle, plankton-feeding basking sharks are also regional endotherms despite having very different lifestyles to white sharks and tunas.

This surprising discovery has implications for conservation, as well as raising a plethora of ecological and evolutionary questions.

Haley Dolton, PhD Candidate in Trinity’s School of Natural Sciences, was lead author of the study that has just been published in international journal, Endangered Species Research. She said:

“The basking shark is a shining example of how little we know about shark species in general. That we still have lots to uncover about the second biggest fish in the world — such a huge, charismatic animal that most people would recognise it — just highlights the challenge facing researchers to gather what they can about species to aid in effective conservation strategies.

Basking sharks gained legal protection in Irish waters just last year, with the species having undergone significant population declines throughout the NE Atlantic in the last century. But they still face many challenges in the future.

Haley Doltonadded: “Regional endotherms are thought to use more energy, and possibly respond differently to ocean warming than other fish species. So lots more work will need to be done to work out how these new findings regarding an endangered species might change previous assumptions about their metabolism or potential distribution shifts during our climate crisis, which is something marine biologists are focusing on as our planet and its seas continue to warm.

“Hopefully this kind of research will continue the momentum needed to effectively protect these incredible animals in Irish waters and further afield.”

To make the discovery, the research team (including scientists from University of Pretoria, Marine Biological Association, Queen’s University Belfast, Zoological Society of London, University of Southampton, and Manx Basking Shark Watch) first undertook dissections of dead basking sharks that washed up in Ireland and the UK.

They found that the sharks have cruise-swimming muscles located deep inside their bodies as seen in white sharks and tunas; in most fish this “red” muscle is instead found toward the outside of the animals.

They also discovered basking sharks have strong muscular hearts that probably help generate high blood pressures and flows. Most fish species have relatively “spongy” hearts, whereas basking shark hearts are more typical of the regional endotherm species.

Next, the team designed a new low-impact tagging method to record body temperature of free-swimming basking sharks off the coast of Co Cork, Ireland. Researchers were able get close enough to 8 m basking sharks to safely deploy the tags, which recorded muscle temperature just under the skin for up to 12 hours before they automatically detached from the animals and were collected by the researchers.

These tags revealed that basking shark muscles are consistently elevated above water temperatures, and to almost exactly the same extent as their regionally-endothermic predatory cousins.

Nicholas Payne, Assistant Professor in Trinity’s School of Natural Sciences, was senior author of the study. He said:

“These results cast an interesting new light on our perception of form versus function in fishes because until now we thought regional endothermy was only found in apex predatory species living at high positions in the marine food web.

“Now we have found a species that grazes on tiny plankton but also shares those rather uncommon regional endotherm features, so we might have to adjust our assumptions about the advantages of such physiological innovations for these animals.

“It’s a bit like suddenly finding that cows have wings.”

“The motivation of this project was really to try and understand how these post-reproductive females are helping their offspring,” says first author Charli Grimes, an animal-behavior scientist at the University of Exeter. “Our results highlight a new pathway by which menopause is adaptive in killer whales.”

The research team studied southern resident orcas, a group of orcas that live off the Pacific Northwest coast. These killer whales live in matriarchal social units that consist of a mother, her offspring, and the offspring of her daughters. Although male orcas will outbreed with whales from other pods, both males and females stay in their unit of birth, with their mother, for life.

Using data from the Center for Whale Research’s annual photographic census of the orca population, the researchers looked for evidence of scarring on each catalogued whale’s skin. Killer whales have no natural predators other than humans, so a tooth mark that is able to puncture an orca’s skin was most likely inflicted by another orca.

The study found that, if a given male’s mother was still alive and no longer reproducing, that male would have fewer tooth marks than his motherless peers or his peers with a mother who was still reproducing.

“It was striking to see how directed the social support was,” says senior author Darren Croft, an animal-behavior scientist at the University of Exeter. “If you have a post-reproductive mother who’s not your mother within the social group, there’s no benefit. It’s not that these females are performing a general policing role. These post-reproductive mothers are targeting the support they are giving to their sons.”

The researchers still can’t say for certain what kinds of social conflicts are leading to tooth marks or how older females are protecting their sons against them. They do note that post-menopause females have the lowest incidence of tooth marks in the entire social unit, suggesting that they do not physically intervene in a conflict. If older orca females play a similar role to that of older women in human societies, they might be acting as mediators, preventing conflict from occurring in the first place. To explore this further, the researchers plan on completing an additional study by using drone footage to observe whale behavior from above.

“It’s possible that with age comes advanced social knowledge. Over time, they might have a better understanding of other social groups,” says Grimes. “Given these close mother-son associations, it could also be that she is present in a situation of conflict so she can signal to her sons to avoid the risky behavior they might be participating in.”

“We’ve got hypotheses, but we need to test them by seeing what’s happening under water when these different groups interact,” says Croft. “We’ve learned so much from this population, but we’ve still got so much to learn from them.”