It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Thursday, August 14, 2025
Seashells inspire a better way to recycle plastic
Using nature’s approach to robust structures, Georgia Tech has created a process that makes normally unpredictable recycled plastic reliable and strong
Georgia Tech researchers used a device to test the reliability and strength of chopped-up sheets of recycled plastic. The video shows several stages as the plastic is torn apart, from initial deformation (white shading) to crack initiation to propagation to final failure.
Researchers from Georgia Tech have created a material inspired by seashells to help improve the process of recycling plastics and make the resulting material more reliable.
The structures they created greatly reduced the variability of mechanical properties typically found in recycled plastic. Their product also maintained the performance of the original plastic materials.
The researchers said their bio-inspired design could help cut manufacturing costs of virgin packaging materials by nearly 50% and offer potential savings of hundreds of millions of dollars. And, because less than 10% of the 350 million tons of plastics produced each year is effectively recycled, the Georgia Tech approach could keep more plastic out of landfills.
Aerospace engineering assistant professor Christos Athanasiou led the study, which was published in the journal Proceedings of the National Academy of Sciences (PNAS).
Why are plastics recycled so infrequently? And when they are recycled, why can’t they be widely reused?
Recycled plastics aren’t pristine materials — they’re a chaotic mix of past lives. Every bottle, bag, and wrapper brings its own history of additives, stress, and degradation. When we recycle them mechanically by melting them all down, we get a material that’s weaker than virgin plastic — and wildly unpredictable. Unpredictability is a dealbreaker.
That’s why recycled plastics rarely make it back into products that need strength, safety, or consistency like construction materials, car components, or autonomous delivery vehicles. They simply can’t be trusted to perform.
Why can seashell structure offer clues for improvement?
Nature doesn’t purify. It organizes.
Seashells, like nacre, are made of brittle minerals glued together by soft proteins. They’re not flawless, but they’re robust. The secret is in the architecture: hard “bricks” connected by soft “mortar,” creating a system that dissipates energy and controls failure. That’s a fundamentally different design philosophy from how we typically engineer materials, where uniformity and purity are the paths to reliability.
Nature embraces variability and makes it manageable through structure. We borrowed that insight.
What did you create, and how did you test it?
We took chopped-up sheets of recycled high-density polyethylene (HDPE) — the same plastic used in industrial stretch wrap — and reassembled them into layered composites inspired by seashells. Think of it as a synthetic nacre structure: stiff plastic “bricks” joined by a softer “mortar” made from a commercial adhesive polymer, engineered to absorb stress and control failure.
Then we developed a new model — a first-of-its-kind uncertainty-aware Tension Shear Chain model. Rather than just assessing how stiff and strong the material was, our model also provided a measure of confidence of how reliably it performed under tension.
What were the results?
We reduced the variability in maximum elongation — a key measure of mechanical performance — by over 68%. Normally, recycled plastics are all over the place in mechanical performance. Our structured composites were consistent. That’s a key requirement for any real-world application.
In other words: we built a structure you can trust, using materials you normally can’t.
HDPE stretch film is the clear material that wraps products stacked on pallets. It can’t do the same job again once it’s been recycled?
Not quite. Stretch film needs to be both strong and flexible. But once it's exposed to sunlight, stress, and heat, its molecular structure changes. Recycling it blindly is like reusing a parachute without checking for rips. Our bio-inspired design doesn’t just reuse the plastic — it restores its reliability, making high-performance reuse possible.
You’re in the School of Aerospace Engineering. This work doesn’t appear to be related to airplanes, rockets, or space. What’s the connection?
Designing the next generation of aerospace systems requires thinking across disciplines and pushing beyond conventional materials. For example, one of the biggest challenges in space engineering is creating structures that don’t fail in unpredictable, extreme environments. Whether it’s a reusable rocket part or a shelter on Mars, we need materials that are resilient across their entire lifecycle.
Our PNAS study tackles a fundamental mechanics problem: how do you build reliable structures from unreliable materials? That’s not just a recycling question. It’s a future-of-space question.
What’s next?
We’re scaling this approach to work with a wider range of recycled plastics while pairing them with greener, bio-based adhesives to make the entire structure more sustainable. At the same time, we’re exploring how this strategy could support off-Earth construction, where recycling and reusing materials is a necessity. NASA’s Lunar Recycling Challenge, for example, points to a future where waste becomes the building block of survival.
CITATION: Georgiou, D., Sun, D., Liu, X, Athanasiou, C. Suppressing Mechanical Property Variability in Recycled Plastics via Bio-inspired Design. Proceedings of the National Academy of Sciences (Vol 122, 2025). https://doi.org/10.1073/pnas.2502613122.
Extreme heat can be hard on your heart. As temperatures rise, the heart pumps faster to move blood toward the skin to cool the body. This added strain on the cardiovascular system can increase the risk of heart attack or stroke, especially for those with existing heart conditions.
The danger can spike dramatically when combined with high humidity, according to a new study from Tulane University that found the risk of visiting the emergency room for a heart-related issue is six times higher during extremely hot and humid days.
The study, published in Science of the Total Environment, analyzed more than 340,000 emergency room visits for heart-related issues in Dhaka, Bangladesh, a city characterized by intense heat and humidity, from 2014 to 2019. Researchers modeled these visits against historical temperature and humidity data. While heat alone increased the risk of a heart-related emergency by 4.4% on low-humidity days, the risk jumped to 26.7% on the most humid days when relative humidity topped 82 percent.
“These findings show we need to consider heat and humidity together when we discuss any kind of climate change policy,” said first author Mostafijur Rahman, an assistant professor of environmental health sciences at the Celia Scott Weatherhead School of Public Health and Tropical Medicine at Tulane University. “We know extreme heat can have a negative health impact, but I never expected such a dramatic increase in risk when high humidity is also factored in.”
Researchers found no association between humidity alone and increased heart-related emergencies. High heat was defined as temperatures above 84 degrees Fahrenheit; exposure to high heat alone was associated with an 8% increase in heart-related emergency visits. However, humidity significantly magnified that risk when levels exceeded 80%. The increase was consistent across age and sex groups.
When combined with high heat, a high level of moisture in the air can limit sweat evaporation, the body’s key cooling mechanism, and force the heart to pump even harder.
The findings are especially significant because household air conditioning is uncommon in Dhaka, and Bangladesh consistently ranks among the countries estimated to be most vulnerable to climate change. As temperatures rise around the globe, Rahman hopes these findings encourage solutions in Bangladesh and similar countries, where exposure to high heat and humidity can drive up the risk of heat-related illness.
“There are billions around the world—from Southeast Asia to Africa—who are directly impacted by rising temperatures but have little access to air conditioning,” Rahman said. “Hopefully governments will be spurred to develop systems to warn cities of dangerous heat and humidity. For average citizens, it’s important to develop habits to beat the heat: stay hydrated, stay indoors, wear breathable clothing, and consider visiting air-conditioned public places like malls or libraries.”
August 13, 2025 — Team creativity can be measured in primary care, according to a new study at Columbia UniversityMailman School of Public Health. Primary care teams are essential to high-quality, patient-centered care yet face persistent challenges despite growing recognition of their operational expertise. Their role as a source of creative ideas for improving care is underleveraged while empirical tools for assessing and supporting creativity in primary care teams also remained scarce. The findings are published in Health Care Management Review.
“In other industries, team creativity is well-studied and is gaining traction in health care, where it may foster innovation and improvement,” said Yuna Lee, PhD, assistant professor of Health Policy and Management at Columbia Mailman School of Public Health, and first author.
“Our goal was to adapt and refine the concept of team creativity for primary care.”
Over the past two decades, primary care in the United States has undergone a wave of innovation in response to persistent challenges, including new models of financing, delivery, and workforce design. At the forefront of these efforts are primary care teams—comprising physicians, nurses, medical assistants, and other staff—who work together to solve problems and adapt care on a daily basis.
The researchers used a three-stage empirical design. First, team creativity dimensions were identified through a review and thematic analysis of management literature. The second stage of the study involved consulting an expert panel of 15 scholars and professionals with experience in primary care who adapted these dimensions for primary care. Third, a survey of 648 primary care team members in a large health system was followed by an analysis to identify core dimensions.
Five dimensions of primary care team creativity emerged:
Team orientation to creativity
Team creative processes
Job-required creativity
Team creative outputs
Leveraging team creativity
“Primary care teams can apply these five dimensions to generate creative ideas in their daily work,” said Lee. “Managers can support this by allocating resources, implementing supportive practices, and recognizing their creative contributions.”
With primary care teams increasingly operating in complex environments shaped by burnout, staffing shortages, care coordination challenges, and complex patient needs, this work offers a foundation for making creativity a core capability in high-performing primary care teams, Lee observed.
“Despite many innovations in primary care, the creative capacity of frontline teams remains underexplored,” Lee points out. “The findings from our study suggest that with supportive dynamics and infrastructure, these teams can generate solutions to persistent challenges—contributing to care quality and operational efficiency.”
Co-authors are Nancy LaVine, Northwell Health and Department of Medicine, Lenox Hill Hospital; Yulia Kogan, Population Health Analytics, Northwell Health; and Lusine Poghosyan, Columbia University School of Nursing and Department of Health Policy and Management, Columbia Mailman School of Public Health.
The study was supported by the Agency for Healthcare Research and Quality, grant 5R03HS027502-02.
Columbia University Mailman School of Public Health
Founded in 1922, the Columbia University Mailman School of Public Health pursues an agenda of research, education, and service to address the critical and complex public health issues affecting New Yorkers, the nation and the world. The Columbia Mailman School is the third largest recipient of NIH grants among schools of public health. Its nearly 300 multi-disciplinary faculty members work in more than 100 countries around the world, addressing such issues as preventing infectious and chronic diseases, environmental health, maternal and child health, health policy, climate change and health, and public health preparedness. It is a leader in public health education with more than 1,300 graduate students from 55 nations pursuing a variety of master’s and doctoral degree programs. The Columbia Mailman School is also home to numerous world-renowned research centers, including ICAP and the Center for Infection and Immunity. For more information, please visit www.mailman.columbia.edu.
Top - a map showing the sampling stations along the research cruise onboard the R/V L’Atalante. Bottom - circulation maps presenting ocean connectivity between stations, reflected in the copepod microbial metacommunities. From: Velasquez et al. (2025).
[13 August 2025] — An international study led by Prof. Tamar Guy-Haim and Dr. Ximena Velasquez from the Israel Oceanographic and Limnological Research (IOLR) has revealed that tiny planktonic crustaceans carry a unique microbial signature that better reflects ocean currents and environmental gradients than microbes found freely in seawater.
Published today in Limnology and Oceanography Letters, the researchers investigated microbial communities associated with copepods across the Mediterranean Sea—one of the world’s most environmentally diverse marine systems, characterized by pronounced west-to-east gradients in temperature, salinity, and nutrients. By comparing microbes living on copepods with those found in seawater, the researchers discovered that copepod microbiomes revealed clearer biogeographic patterns that reflect environmental gradients and ocean circulation.
“These microbes travel with their copepod hosts”, explains lead author Dr. Ximena Velasquez. “Because copepods dispersal is more limited by ocean currents than free-living microbes, their associated microbes are shaped by where they are and how they move, creating a ‘microbial map’ of ocean regions”.
The study brought together experts from Israel, Italy, Greece, and France, collecting samples aboard the French research vessel L’Atalante during a five-week expedition from the western Mediterranean off France to the eastern Mediterranean near Crete. The fieldwork took place in the midst of the COVID-19 pandemic, adding logistical challenges. “Every day we towed plankton nets and collected water samples”, recalls Velasquez. “I set hours by the stereomicroscope in our ship’s lab to identify and carefully pick the copepods, one by one, even when the sea was rough. Despite everything, it was an unforgettable and enjoyable experience”.
“Marine microbial metacommunities are networks of communities”, explains Prof. Tamar Guy-Haim. “At local scales, copepod microbial communities are host-specific and strongly influenced by traits like diet and feeding behavior, as we found in a previous research. But over large oceanic distances, copepods can share microbes directly with one another or indirectly via the environment, forming what we call a microbial metacommunity”.
Using genetic tools and evolutionary models, the researchers discovered that copepod-associated microbial metacommunities were alike in Mediterranean basins linked by ocean currents, but distinctly different in basins that were not connected. By contrast, free-living microbes in seawater were more uniform everywhere and tended to be dominated by common, widespread species.
“This suggests that copepod-associated microbes are more sensitive indicators of regional changes in ocean conditions”, says Guy-Haim. “They could serve as valuable bioindicators for detecting shifts in marine ecosystems, especially under climate change”.
As surface oceans become warmer and more nutrient-depleted, these host-associated microbes, especially those adapted to oligotrophic conditions, may offer early warning signs about the health of marine ecosystems. The findings open new avenues for tracking how host-associated microbial communities, and the ecosystems they inhabit, are changing on a global scale.
Top right Dr. Ximena Velasquez picking copepods from plankton samples.
Top left – copepods collected for the research. Bottom – The research team.
Left – Plankton nets. Right – Rosette mounted with Niskin bottles, collecting seawater from different depths.
Sampling from palnkton nets during the COVID pandemic
Using X-ray spectrometry, archaeologists have found a way to distinguish iron from different time periods in America's colonial past, which may result in long-anticipated discoveries.
Iron artifacts from early Spanish expeditions in North America often look too similar to tell apart, making it difficult to establish the exact routes that were taken.
In a new study, archaeologists analyzed iron artifacts spanning more than 400 years of American colonial history using X-ray fluorescence spectroscopy. Their results show that differences in the purity of iron and the trace elements it contains can be reliably used as a diagnostic feature to identify iron artifacts from different time periods.
This method may be sensitive enough to distinguish iron artifacts from Spanish expeditions separated by only a few decades, but the study authors say more data needs to be collected to be sure.
On a dark night in late May 1543, a group of men snuck through the Native American town of Guachoya and stopped at the gated wall, where a body had recently been buried. Working quietly, they disinterred the body and carried it to a nearby river, where they wrapped it in shawls filled with sand and dropped it in the water. Thus ended the brief and brutal history of Hernando de Soto, a Spanish soldier who helped conquer Nicaragua, overthrow the Inca empire in Peru and famously led an extensive expedition and military campaign from present-day Florida up through South Carolina and west to Arkansas.
His men had decided to bury his body at first, but given that he’d convinced the Indigenous inhabitants that he was a god before he died of an unknown illness — a decidedly ungodlike thing to do — they later committed his body to a tributary of the Mississippi River, hoping no one would find him.
De Soto’s expedition represented the longest sustained 16th-century incursion of Europeans into North America, but it was preceded and followed by several others, 15 in all. That’s a problem for archaeologists. The Spanish left behind detailed records of their exploits in the Americas, but because they only had a vague sense of where they were at any given time, the exact routes they took remains unclear.
Archaeologists have sidestepped this issue by looking for things the Spanish left behind, especially iron, which they brought with them in great quantities. But the various expeditions, which often overlapped, makes things complicated.
“A wrought-iron nail from the 1500s looks like a wrought iron nail from the 1600s,” said Charles Cobb, the Lockwood chair in historical archaeology at the Florida Museum of Natural History.
Nails account for more than half of all metal artifacts found in North America. This, of itself, is no small problem, said Lindsay Bloch, a courtesy faculty member at the Florida Museum and principal investigator at Tempered Archaeological Services. “Archaeologists find lots and lots of rusty nails and other rusty iron objects. We often can’t even tell what they are, so they get weighed, counted and put back in their bag. And usually, no one ever looks at them again,” she said.
The Spanish had more than just nails. They used iron to make axe blades, horseshoes, breastplates, helmets, spokes, spears, knives, guns and more. They even brought along blacksmiths and farriers on their expeditions to repair and repurpose things on the go. But these objects, like nails, are typically indistinguishable through time. From the moment Christopher Columbus laid anchor in the Bahamas through the conquest of Florida, there were too few changes in the style of metalworking for there to be readily observable diagnostic differences between iron objects made by the Spanish.
That may be about to change. Both Cobb and Bloch are coauthors of a new study in which they demonstrate that microscopic differences in iron from this time period can be spotted using X-ray fluorescence spectrometry. They made this discovery by analyzing objects of unknown affinity, which they now think may have come from the de Soto expedition.
Custer’s last stand elevated the status of metal detectors, resulting in big discoveries
The new methodology follows on the heels of a quiet revolution that’s been taking place in southeast archaeology, namely the recent adoption of metal detectors in large-scale survey work.
This kind of change might seem like a no-brainer from the outside. If an absolute novice were told to find ancient metal artifacts, a metal detector is probably the first thing they’d reach for. But these devices are in many ways antithetical to long-established — and successful — methods of archaeological excavation.
Before metal detectors existed, archaeologists relied solely on their own experience and intuition to find things. They’d set up a transect in a likely spot and dig test holes at regular intervals or scour a predetermined area for objects that had been exposed to the elements. Whenever they found something, they’d clear away an excavation plot and slowly, meticulously work their way down through the sediment horizons while noting the exact location of each object. These methods are rigorously thorough and still in use. They’ve contributed the majority of what we know about ancient cultures that wasn’t put down in writing.
When the first portable metal detectors were invented in the 1930s, archaeologists didn’t have much of a need for them. But metal detectors did catch on with another group: Hobbyists and treasure hunters began finding metal objects all over the place, which they often kept or sold for profit. This didn’t sit well with archaeologists, who were of the opinion shared by Indiana Jones that such things belong in a museum.
“Metal detectors have a bad reputation in archaeology because they are often the go-to for people who loot historic sites,” Bloch said.
So, for several decades, most archaeologists wouldn’t have been caught dead with a metal detector, until 1983, when a wildfire in Montana cleared away the dense vegetation that covered the site of Lt. Col. George Armstrong Custer’s last stand at the Battle of Little Bighorn. The conflict between the U.S. Army and an alliance of Indigenous tribes had taken place over a large area, which made the standard archaeological approach of shovel testing impractical. An enterprising research team, not wanting to waste the narrow window of opportunity, decided to give metal detection a try.
Their gumption paid off. Archaeologists recovered such a great amount and variety of munitions that they were able to retrace the harried steps of U.S. troops, who were routed during the two-day battle.
Other archaeologists took note. “That made it a bit more legitimate for people, but it still took a long time for it to catch on, and it still hasn’t caught on completely,” Cobb said.
For his part, Cobb has no qualms with metal detectors and has made consistent use of them for the last several years. His first big breakthrough came in 2015, when he participated in an archaeological survey in Mississippi. The survey was primarily undertaken to locate ancestral Chickasaw sites. On a whim, they decided to bring out a few metal detectors. Native Americans often traded iron objects they obtained from the Spanish, so it was reasonable to expect there might be a few items lying around that might be indicative of a former habitation. Instead, they discovered what was likely the site of a major battle between de Soto’s army and the Chickasaw that archaeologists had spent decades searching for.
Other breakthroughs soon followed. Before about 15 years ago, less than 100 European objects had been found at North American Indigenous sites outside of Florida. That number has since swiftly increased, leaving archaeologists looking for better ways to determine who these objects belonged to.
One option would be to analyze impurities in the iron. The process of refining iron ore by smelting and forging it leaves a substance that is very nearly 100% iron, but not quite. The more forging a metal is subjected to, the purer its content will be, but trace elements like copper, vanadium and manganese stubbornly resist removal. The proportions of those trace elements are specific to the geographic location where they were deposited. These differences can theoretically be used to determine where a hunk of iron had originally been mined from.
Metals lend themselves well to X-ray analysis because of their high density, and fortunately for Cobb, an expert on the subject happened to work just down the hall from his office.
“She won’t brag on herself, but Lindsay literally wrote the manual on how archaeologists should use X-ray fluorescence spectrometry when she was a grad student,” Cobb said.
The purity of iron artifacts and the trace elements they contain differ through time
Since their study was intended as a proof of concept, the authors decided to cast a wide net by looking at iron material from multiple places and time periods associated with Spanish colonialism. Among the sites included were the first Spanish colony in the Americas, established by Columbus in 1492; several Spanish missions; the 16th century capital of La Florida (located in present-day South Carolina); the de Soto/Chickasaw battle site Cobb had helped excavate; a British fort; and three 19th century plantations.
They also included iron from a site in Alabama known as the Marengo complex. The area comprises excavations from several villages and is believed to be somewhere near the Indigenous town of Mabila, where de Soto’s men engaged in an even more devastating battle than the one they’d have with the Chickasaw a few months later.
Although objects from the Chickasaw battle unambiguously came from the de Soto expedition, the provenance of those from the Marengo complex is less certain. De Soto certainly traveled through the area and left behind a significant store of supplies after the loss of life incurred during the fighting, which reduced the expedition’s ability to haul heavy equipment through the wilderness.
But two decades later, another Spanish expedition came through the area led by Tristán de Luna, who established a nearby settlement that has also yet to be discovered. Grueling starvation and conflict forced de Luna to abandon the settlement, leaving behind supplies that would have been virtually indistinguishable from those of his predecessor. Thus, archaeologists working at the Marengo complex can’t be sure which of the two expeditions artifacts in the area came from.
Though de Soto and de Luna visited some of the same places and were met with similar fates (though De Luna was merely deposed by his men rather than dying outright), their expeditions differ in one important regard. De Soto lived in Spain when he began assembling ships, men and supplies for the trip, and he sourced all of his iron equipment from Europe. De Luna got his supplies from New Spain in South America. He also strongly relied on his men to bring their own assorted iron tools along.
In an early test of the X-ray fluorescence spectrometry method in archaeology, a 2013 study of iron artifacts from Pensacola (known to have come from De Luna) and others from Tallahassee (thought to have come from de Soto) yielded tantalizing but inconclusive results indicating there were elemental differences between the two.
Hoping to find something more robust, Bloch scanned the assemblage of artifacts they’d gathered with a handheld X-ray spectrometer and held her breath.
As a proof of concept, the results were a success. The types of impurities in iron varied markedly through time. The authors say the differences were so consistent that, going forward, they can be reliably used as a diagnostic feature. Small amounts of manganese, for example, were found in some artifacts from the 16th century, but this element was almost entirely absent in iron from later periods. Bismuth was more likely to show up in 18th and 19th century artifacts, and several impurities — including titanium, ruthenium and zirconium — were associated with iron from the late 16th and the 17th centuries.
The overall quality of iron also differed through the ages. Iron artifacts from the mid-16th century had the fewest impurities, and of these, horseshoes had the highest iron content. There was a significant dip in iron quality associated with the 16th and 17th centuries, corresponding with the greater variety of impurities in artifacts from this time. The quality of iron from later periods improved, but it never reached the level of purity found in objects from the early expeditions.
Their results also suggested that the iron recovered from the Marengo complex had likely come from de Soto, but the authors say it’s still too soon to tell. To be certain, they’ll need to take measurements from additional objects that they can pinpoint to specific expeditions that can be used as a standard. And X-rays, while proven to be informative in archaeological contexts, are the quick and dirty way to collect data. To really get down to the fine-grained differences, Cobb said, they will need use a method called isotopic analysis, which gives more precise (and expensive) results. The authors are currently in the process of applying for a grant that would allow them to do just that.
The authors published their study in the International Journal of Historical Archaeology.
