chemistry

A fluid can store solar energy and then release it as heat months later

chemistry, green, heating, materials science, renewable energy, Science, solar / Paul Patrick / February 16, 2026

Sunlight can cause a molecule to change structure, and then release heat later.

The system works a bit like existing solar water heaters, but with chemical heat storage. Credit: Kypros

Heating accounts for nearly half of the global energy demand, and two-thirds of that is met by burning fossil fuels like natural gas, oil, and coal. Solar energy is a possible alternative, but while we have become reasonably good at storing solar electricity in lithium-ion batteries, we’re not nearly as good at storing heat.

To store heat for days, weeks, or months, you need to trap the energy in the bonds of a molecule that can later release heat on demand. The approach to this particular chemistry problem is called molecular solar thermal (MOST) energy storage. While it has been the next big thing for decades, it never really took off.

In a recent Science paper, a team of researchers from the University of California, Santa Barbara, and UCLA demonstrate a breakthrough that might finally make MOST energy storage effective.

The DNA connection

In the past, MOST energy storage solutions have been plagued by lackluster performance. The molecules either didn’t store enough energy, degraded too quickly, or required toxic solvents that made them impractical. To find a way around these issues, the team led by Han P. Nguyen, a chemist at the University of California, Santa Barbara, drew inspiration from the genetic damage caused by sunburn. The idea was to store energy using a reaction similar to the one that allows UV light to damage DNA.

When you stay out on the beach too long, high-energy ultraviolet light can cause adjacent bases in the DNA (thymine, the T in the genetic code) to link together. This forms a structure known as a (6-4) lesion. When that lesion is exposed to even more UV light, it twists into an even stranger shape called a “Dewar” isomer. In biology, this is rather bad news, as Dewar isomers cause kinks in the DNA’s double-helix spiral that disrupt copying the DNA and can lead to mutations or cancer.

To counter this effect, evolution shaped a specific enzyme called photolyase to hunt (6-4) lesions down and snap them back into their safe, stable forms.

The researchers realized that the Dewar isomer is essentially a molecular battery. This snap-back effect was exactly what Nguyen’s team was looking for, since it releases a lot of heat.

Rechargeable fuel

Molecular batteries, in principle, are extremely good at storing energy. Heating oil, arguably the most popular molecular battery we use for heating, is essentially ancient solar energy stored in chemical bonds. Its energy density stands at around 40 Megajoules per kilo. To put that in perspective, Li-ion batteries usually pack less than one MJ/kg. One of the problems with heating oil, though, is that it is single-use only—it gets burnt when you use it. What Nguyen and her colleagues aimed to achieve with their DNA-inspired substance is essentially a reusable fuel.

To do that, researchers synthesized a derivative of 2-pyrimidone, a chemical cousin of the thymine found in DNA. They engineered this molecule to reliably fold into a Dewar isomer under sunlight and then unfold on command. The result was a rechargeable fuel that could absorb the energy when exposed to sunlight, release it when needed, and return to a “relaxed” state where it’s ready to be charged up again.

Previous attempts at MOST systems have struggled to compete with Li-ion batteries. Norbornadiene, one of the best-studied candidates, tops out at around 0.97 MJ/kg. Another contender, azaborinine, manages only 0.65 MJ/kg. They may be scientifically interesting, but they are not going to heat your house.

Nguyen’s pyrimidone-based system blew those numbers out of the water. The researchers achieved an energy storage density of 1.65 MJ/kg—nearly double the capacity of Li-ion batteries and substantially higher than any previous MOST material.

Double rings

The reason for this jump in performance was what the team called compounded strain.

When the pyrimidone molecule absorbs light, it doesn’t just fold; it twists into a fused, bicyclic structure containing two different four-membered rings: 1,2-dihydroazete and diazetidine. Four-membered rings are under immense structural tension. By fusing them together, the researchers created a molecule that is desperate to snap back into its relaxed state.

Achieving high energy density on paper is one thing. Making it work in the real world is another. A major failing of previous MOST systems is that they are solids that need to be dissolved in solvents like toluene or acetonitrile to work. Solvents are the enemy of energy density—by diluting your fuel to 10 percent concentration, for example, you effectively cut your energy density by 90 percent. Any solvent used means less fuel.

Nguyen’s team tackled this by designing a version of their molecule that is a liquid at room temperature, so it doesn’t need a solvent. This simplified operations considerably, as the liquid fuel could be pumped through a solar collector to charge it up and store it in a tank.

Unlike many organic molecules that hate water, Nguyen’s system is compatible with aqueous environments. This means if a pipe leaks, you aren’t spewing toxic fluids like toluene around your house. The researchers even demonstrated that the molecule could work in water and that its energy release was intense enough to boil it.

The MOST-based heating system, the team says in their paper, would circulate this rechargeable fuel through panels on the roof to capture the sun’s light and then store it in the basement tank. The fuel from this tank would later be pumped to a reaction chamber with an acid catalyst that triggers the energy release. Then, through a heat exchanger, this energy would heat up the water in the standard central heating system.

But there’s a catch.

Looking for the leak

The first hurdle is the spectrum of light that puts energy in the Nguyen’s fuel. The Sun bathes us in a broad spectrum of light, from infrared to ultraviolet. Ideally, a solar collector should use as much of this as possible, but the pyrimidone molecules only absorb light in the UV-A and UV-B range, around 300-310 nm. That represents about five percent of the total solar spectrum. The vast majority of the Sun’s energy, the visible light and the infrared, passes right through Nguyen’s molecules without charging them.

The second problem is quantum yield. This is a fancy way of asking, “For every 100 photons that hit the molecule, how many actually make it switch to the Dewar isomer state?” For these pyrimidones, the answer is a rather underwhelming number, in the single digits. Low quantum yield means the fluid needs a longer exposure to sunlight to get a full charge.

The researchers hypothesize that the molecule has a fast leak, meaning a non-radiative decay path where the excited molecule shakes off the energy as heat immediately instead of twisting into the storage form. Plugging that leak is the next big challenge for the team.

Finally, the team in their experiments used an acid catalyst that was mixed directly into the storage material. The team admits that in a future closed-loop device, this would require a neutralization step—a reaction that eliminates the acidity after the heat is released. Unless the reaction products can be purified away, this will reduce the energy density of the system.

Still, despite the efficiency issues, the stability of the Nguyen’s system looks promising.

The MOST storage?

One of the biggest fears with chemical storage is thermal reversion—the fuel spontaneously discharges because it got a little too warm in the storage tank. But the Dewar isomers of the pyrimidones are incredibly stable. The researchers calculated a half-life of up to 481 days at room temperature for some derivatives. This means the fuel could be charged in the heat of July, and it would remain fully charged when you need to heat your home in January. The degradation figures also look decent for a MOST energy storage. The team ran the system through 20 charge-discharge cycles with negligible decay.

The problem with separating the acid from the fuel could be solved in a practical system by switching to a different catalyst. The scientists suggest in the paper that in this hypothetical setup, the fuel would flow through an acid-functionalized solid surface to release heat, thus eliminating the need for neutralization afterwards.

Still, we’re rather far away using MOST systems for heating actual homes. To get there, we’re going to need molecules that absorb far more of the light spectrum and convert to the activated state with a higher efficiency. We’re just not there yet.

Science, 2026. DOI: 10.1126/science.aec6413

Jacek Krywko is a freelance science and technology writer who covers space exploration, artificial intelligence research, computer science, and all sorts of engineering wizardry.

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COVID-19 cleared the skies but also supercharged methane emissions

atmospheric science, chemistry, climate change, Covid, greenhouse gasses, methane, pandemic, pollution, Science / Kris Guyer / February 6, 2026

The remaining question, though, was where all this methane was coming from in the first place. Throughout the pandemic, there was speculation that the surge might be caused by super-emitter events in the oil and gas sector, or perhaps a lack of maintenance on leaky infrastructure during lockdowns.

But the new research suggests that the source of these emissions was not what many expected.

The microbial surge

While the weakened atmospheric sink explained the bulk of the 2020 surge, it wasn’t the only factor at play. The remaining 20 percent of the growth, and an even larger portion of the growth in 2021 and 2022, came from an increase in actual emissions from the ground. To track the source of these emissions down, Peng’s team went through tons of data from satellites and various ground monitoring stations.

Methane comes in different isotopic signatures. Methane from fossil fuels like natural gas leaks or coal mines is heavier, containing a higher fraction of the stable isotope carbon-13. Conversely, methane produced by microbes found in the guts of livestock, in landfills, and most notably in wetlands, is lighter, enriched in carbon-12.

When the researchers analyzed data from the National Oceanic and Atmospheric Administration global flask network, a worldwide monitoring system tracking the chemical composition of Earth’s atmosphere, they found that the atmospheric methane during the mysterious surge was becoming significantly lighter. This was a smoking gun for biogenic sources. The surge wasn’t coming from pipes or power plants; it was coming from microbes.

La Niña came to play

The timing of the pandemic coincided with a relatively rare meteorological event. La Niña, the cool phase of the El Niño–Southern Oscillation that typically leads to increased rainfall in the tropics, lasted for three consecutive Northern Hemisphere winters (from 2020 to 2023). This made the early 2020s exceptionally wet.

The researchers used satellite data from the Greenhouse Gases Observing Satellite and sophisticated atmospheric models to trace the source of the light methane to vast wetland areas in tropical Africa and Southeast Asia. In regions like the Sudd in South Sudan and the Congo Basin, record-breaking rainfall flooded massive swaths of land. In these waterlogged, oxygen-poor environments, microbial methanogens thrived, churning out methane at an accelerated pace.

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A century of hair samples proves leaded gas ban worked

chemistry, geochemistry, leaded gasoline, Science / Kris Guyer / February 2, 2026

Science also produced a hero in this saga: Caltech geochemist Clair Patterson. Along with George Tilton, Patterson developed a lead-dating method and used it to calculate the age of the Earth (4.55 billion years), based on analysis of the Canton Diablo meteorite. And he soon became a leading advocate for banning leaded gasoline and the “leaded solder” used in canned foods. This put Patterson at odds with some powerful industry lobbies, for which he paid a professional price.

But his many experimental findings on the extent of lead contamination and its toxic effects ultimately led to the rapid phase-out of lead in all standard automotive gasolines. Prior to the EPA’s actions in the 1970s, most gasolines contained about 2 grams of lead per gallon, which quickly adds up to nearly 2 pounds of lead released via automotive exhaust into the environment, per person, every year.

The proof is in our hair

The U.S. Mining and Smelting Co. plant in Midvale, Utah, 1906. — The US Mining and Smelting Co. plant in Midvale, Utah, 1906. Credit: Utah Historical Society

Lead can linger in the air for several days, contaminating one’s lungs, accumulating in living tissue, and being absorbed by one’s hair. Cerling had previously developed techniques to determine where animals lived and their diet by analyzing hair and teeth. Those methods proved ideal for analyzing hair samples from Utah residents who had previously participated in an earlier study that sampled their blood.

The subjects supplied hair samples both from today and when they were very young; some were even able to provide hair preserved in family scrapbooks that had belonged to their ancestors. The Utah population is well-suited for such a study because the cities of Midvale and Murray were home to a vibrant smelting industry through most of the 20th century; most other smelters in the region closed down in the 1970s when the EPA cracked down on using lead in consumer products.

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New battery idea gets lots of power out of unusual sulfur chemistry

anode, batteries, cathode, chemistry, materials science, Science, sodium, sulfur / Mike M. / January 7, 2026

When the battery starts discharging, the sulfur at the cathode starts losing electrons and forming sulfur tetrachloride (SCl₄), using chloride it stole from the electrolyte. As the electrons flow into the anode, they combine with the sodium, which plates onto the aluminum, forming a layer of sodium metal. Obviously, this wouldn’t work with an aqueous electrolyte, given how powerfully sodium reacts with water.

High capacity

To form a working battery, the researchers separated the two electrodes using a glass fiber material. They also added a porous carbon material to the cathode to keep the sulfur tetrachloride from diffusing into the electrolyte. They used various techniques to confirm that sodium was being deposited on the aluminum and that the reaction at the cathode was occurring via sulfur dichloride intermediates. They also determined that sodium chloride was a poor source of sodium ions, as it tended to precipitate out onto some of the solid materials in the battery.

The battery was also fairly stable, surviving 1,400 cycles before suffering significant capacity decay. Higher charging rates caused capacity to decay more quickly, but the battery did a great job of holding a charge, maintaining over 95 percent, even when idled for 400 days.

While the researchers provide some capacity-per-weight measurements, they don’t do so for a complete battery, focusing instead on portions of the battery, such as the sulfur or the total electrode mass.

But with both electrodes considered, the energy density can reach over 2,000 Watt-hours per kilogram. While that will undoubtedly drop with the total mass of the battery, it’s difficult to imagine that it wouldn’t outperform existing sodium-sulfur or sodium-ion batteries.

Beyond the capacity, the big benefit of the proposed system appears to be its price. Given the raw materials, the researchers estimate that their cost is roughly $5 per kilowatt-hour of capacity, which is less than a tenth of the cost of current sodium batteries.

Again, there’s no guarantee that this work can be scaled up for manufacturing in a way that keeps it competitive with current technologies. Still, if the materials used in existing battery technologies become expensive, it’s reassuring to have other options.

Nature, 2026. DOI: 10.1038/s41586-025-09867-2 (About DOIs).

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Research roundup: 6 cool stories we almost missed

animals, Biology, chemistry, fermentation, microbiology, Physics, psychology, robotics, Science, social networks / Rejus Almole / December 1, 2025

The assassination of a Hungarian duke, why woodpeckers grunt when they peck, and more.

Skull of remains found in a 13th century Dominican monastery on Margaret Island, Budapest, Hungary Credit: Eötvös Loránd University

It’s a regrettable reality that there is never enough time to cover all the interesting scientific stories we come across each month. In the past, we’ve featured year-end roundups of cool science stories we (almost) missed. This year, we’re experimenting with a monthly collection. November’s list includes forensic details of the medieval assassination of a Hungarian duke, why woodpeckers grunt when they peck, and more evidence that X’s much-maligned community notes might actually help combat the spread of misinformation after all.

An assassinated medieval Hungarian duke

The observed perimortem lesions on the human remains (CL=cranial lesion, PL= Postcranial lesion). The drawing of the skeleton was generated using OpenAI’s image generation tools (DALL·E) via ChatGPT. — Credit: Tamás Hajdu et al., 2026

Back in 1915, archaeologists discovered the skeletal remains of a young man in a Dominican monastery on Margaret Island in Budapest, Hungary. The remains were believed to be those of Duke Bela of Masco, grandson of the medieval Hungarian King Bela IV. Per historical records, the young duke was brutally assassinated in 1272 by a rival faction and his mutilated remains were recovered by the duke’s sister and niece and buried in the monastery.

The identification of the remains was based on a contemporary osteological analysis, but they were subsequently lost and only rediscovered in 2018. A paper published in the journal Forensic Science International: Genetics has now confirmed that identification and shed more light on precisely how the duke died. (A preprint is available on bioRxiv.]

An interdisciplinary team of researchers performed various kinds of bioarchaeological analysis on the remains. including genetic testing, proteomics, 3D modeling, and radiocarbon dating. The resulting data definitively proves that the skeleton is indeed that of Duke Bela of Masco.

The authors were also able to reconstruct the manner of the duke’s death, concluding that this was a coordinated attack by three people. One attacked from the front while the other two attacked from the left and right sides, and the duke was facing his assassins and tried to defend himself. The weapons used were most likely a saber and a long sword, and the assassins kept raining down blows even after the duke had fallen to the ground. The authors concluded that while the attack was clearly planned, it was also personal and fueled by rage or hate.

DOI: Forensic Science International: Genetics, 2025. 10.1016/j.fsigen.2025.103381 (About DOIs).

Why woodpeckers grunt when they peck

A male Pileated woodpecker foraging on a t

Woodpeckers energetically drum away at tree trunks all day long with their beaks and yet somehow never seem to get concussions, despite the fact that such drumming can produce deceleration forces as high as 1,200 g’s. (Humans suffer concussions with a sudden deceleration of just 100 g’s.) While popular myth holds that woodpecker heads are structured in such a way to absorb the shock, and there has been some science to back that up, more recent research found that their heads act more like hammers than shock absorbers. A paper published in the Journal of Experimental Biology sheds further light on the biomechanics of how woodpeckers essentially turn themselves into hammers and reveals that the birds actually grunt as they strike wood.

The authors caught eight wild downy woodpeckers and recorded them drilling and tapping on pieces of hardwood in the lab for three days, while also measuring electrical signals in their heads, necks, abdomens, tails, and leg muscles. Analyzing the footage, they found that woodpeckers use their hip flexors and front neck muscles to propel themselves forward as they peck while tipping their heads back and bracing themselves using muscles at the base of the skull and back of the neck. The birds use abdominal muscles for stability and brace for impact using their tail muscles to anchor their bodies against a tree. As for the grunting, the authors noted that it’s a type of breathing pattern used by tennis players (and martial artists) to boost the power of a strike.

DOI: Journal of Experimental Biology, 2025. 10.1242/jeb.251167 (About DOIs).

Raisins turn water into wine

wine glass half filled with raisins — Credit: Kyoto University

Fermentation has been around in some form for millennia, relying on alcohol-producing yeasts like Saccharomyces cerevisiae; cultured S. cerevisiae is still used by winemakers today. It’s long been thought that winemakers in ancient times stored fresh crushed grapes in jars and relied on natural fermentation to work its magic, but recent studies have called this into question by demonstrating that S. cerevisiae colonies usually don’t form on fresh grape skins. But the yeast does like raisins, as Kyoto University researchers recently discovered. They’ve followed up that earlier work with a paper published in Scientific Reports, demonstrating that it’s possible to use raisins to turn water into wine.

The authors harvested fresh grapes and dried them for 28 days. Some were dried using an incubator, some were sun-dried, and a third batch was dried using a combination of the two methods. The researchers then added the resulting raisins to bottles of water—three samples for each type of drying process—sealed the bottles, and stored them at room temperature for two weeks. One incubator-dried sample and two combo samples successfully fermented, but all three of the sun-dried samples did so, and at higher ethanol concentrations. Future research will focus on identifying the underlying molecular mechanisms. And for those interested in trying this at home, the authors warn that it only works with naturally sun-dried raisins, since store-bought varieties have oil coatings that block fermentation.

DOI: Scientific Reports, 2025. 10.1038/s41598-025-23715-3 (About DOIs).

An octopus-inspired pigment

An octopus camouflages itself with the seafloor. — Credit: Charlotte Seid

Octopuses, cuttlefish, and several other cephalopods can rapidly shift the colors in their skin thanks to that skin’s unique complex structure, including layers of chromatophores, iridophores, and leucophores. A color-shifting natural pigment called xanthommatin also plays a key role, but it’s been difficult to study because it’s hard to harvest enough directly from animals, and lab-based methods of making the pigment are labor-intensive and don’t yield much. Scientists at the University of San Diego have developed a new method for making xanthommatin in substantially larger quantities, according to a paper published in Nature Biotechnology.

The issue is that trying to get microbes to make foreign compounds creates a metabolic burden, and the microbes hence resist the process, hindering yields. The USD team figured out how to trick the cells into producing more xanthommatin by genetically engineering them in such a way that making the pigment was essential to a cell’s survival. They achieved yields of between 1 and 3 grams per liter, compared to just five milligrams of pigment per liter using traditional approaches. While this work is proof of principle, the authors foresee such future applications as photoelectronic devices and thermal coatings, dyes, natural sunscreens, color-changing paints, and environmental sensors. It could also be used to make other kinds of chemicals and help industries shift away from older methods that rely on fossil fuel-based materials.

DOI: Nature Biotechnology, 2025. 10.1038/s41587-025-02867-7 (About DOIs).

A body-swap robot

Participant standing on body-swap balance robot — Credit: Sachi Wickramasinghe/UBC Media Relations

Among the most serious risks facing older adults is falling. According to the authors of a paper published in Science Robotics, standing upright requires the brain to coordinate signals from the eyes, inner ears, and feet to counter gravity, and there’s a natural lag in how fast this information travels back and forth between brain and muscles. Aging and certain diseases like diabetic neuropathy and multiple sclerosis can further delay that vital communication; the authors liken it to steering a car with a wheel that responds half a second late. And it’s a challenge to directly study the brain under such conditions.

That’s why researchers at the University of British Columbia built a large “body swap” robotic platform. Subjects stood on force plates attached to a motor-driven backboard to reproduce the physical forces at play when standing upright: gravity, inertia, and “viscosity,” which in this case describes the damping effect of muscles and joints that allow us to lean without falling. The platform is designed to subtly alter those forces and also add a 200-millisecond delay.

The authors tested 20 participants and found that lowering inertia and making the viscosity negative resulted in similar instability to that which resulted from a signal delay. They then brought in ten new subjects to study whether adjusting body mechanics could compensate for information delays. They found that adding inertia and viscosity could at least partially counter the instability that arose from signal delay—essentially giving the body a small mechanical boost to help the brain maintain balance. The eventual goal is to design wearables that offer gentle resistance when an older person starts to lose their balance, and/or help patients with MS, for example, adjust to slower signal feedback.

DOI: Science Robotics, 2025. 10.1126/scirobotics.adv0496 (About DOIs).

X community notes might actually work

cropped image of phone screen showing an X post with a community note underneath — Credit: Huaxia Rui

Earlier this year, Elon Musk claimed that X’s community notes feature needed tweaking because it was being gamed by “government & legacy media” to contradict Trump—despite vigorously defending the robustness of the feature against such manipulation in the past. A growing body of research seems to back Musk’s earlier stance.

For instance, last year Bloomberg pointed to several studies suggesting that crowdsourcing worked just as well as using professional fact-checkers when assessing the accuracy of news stories. The latest evidence that crowd-sourcing fact checks can be effective at curbing misinformation comes from a paper published in the journal Information Systems Research, which found that X posts with public corrections were 32 percent more likely to be deleted by authors.

Co-author Huaxia Rui of the University of Rochester pointed out that community notes must meet a threshold before they will appear publicly on posts, while those that do not remain hidden from public view. Seeing a prime opportunity in the arrangement, Rui et al. analyzed 264,600 X posts that had received at least one community note and compared those just above and just below that threshold. The posts were collected from two different periods: June through August 2024, right before the US presidential election (when misinformation typically surges), and the post-election period of January and February 2025.

The fact that roughly one-third of authors responded to public community notes by deleting the post suggests that the built-in dynamics of social media (e.g., status, visibility, peer feedback) might actually help improve the spread of misinformation as intended. The authors concluded that crowd-checking “strikes a balance between First Amendment rights and the urgent need to curb misinformation.” Letting AI write the community notes, however, is probably still a bad idea.

DOI: Information Systems Research, 2025. 10.1287/isre.2024.1609 (About DOIs).

Jennifer is a senior writer at Ars Technica with a particular focus on where science meets culture, covering everything from physics and related interdisciplinary topics to her favorite films and TV series. Jennifer lives in Baltimore with her spouse, physicist Sean M. Carroll, and their two cats, Ariel and Caliban.

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Why synthetic emerald-green pigments degrade over time

art conservation, chemistry, culture, pigments, Science / Kris Guyer / November 24, 2025

Perhaps most relevant to this current paper is a 2020 study in which scientists analyzed Munch’s The Scream, which was showing alarming signs of degradation. They concluded the damage was not the result of exposure to light, but humidity—specifically, from the breath of museum visitors, perhaps as they lean in to take a closer look at the master’s brushstrokes.

Let there be (X-ray) light

Co-author Letizia Monico during the experiments at the European Synchrotron. ESRF

Emerald-green pigments are particularly prone to degradation, so that’s the pigment the authors of this latest paper decided to analyze. “It was already known that emerald-green decays over time, but we wanted to understand exactly the role of light and humidity in this degradation,” said co-author Letizia Monico of the University of Perugia in Italy.

The first step was to collect emerald-green paint microsamples with a scalpel and stereomicroscope from an artwork of that period—in this case, The Intrigue (1890) by James Ensor, currently housed in the Royal Museum of Fine Arts, in Antwerp, Belgium. The team analyzed the untreated samples using Fourier transform infrared imaging, then embedded the samples in polyester resin for synchrotron radiation X-ray analysis. They conducted separate analyses on both commercial and historical samples of emerald-green pigment powders and paint tubes, including one from a museum collection of paint tubes used by Munch.

Next, the authors created their own paint mockups by mixing commercial emerald-green pigment powders and their lab-made powders with linseed oil, and then applied the concoctions to polycarbonate substrates. They also squeezed paint from the Munch paint tube onto a substrate. Once the mockups were dry, thin samples were sliced from each mockup and also analyzed with synchrotron radiation. Then the mockups were subjected to two aging protocols designed to determine the effects of UV light (to simulate indoor lighting) and humidity on the pigments.

The results: In the mockups, light and humidity trigger different degradation pathways in emerald-green paints. Humidity results in the formation of arsenolite, making the paint brittle and prone to flaking. Light dulls the color by causing trivalent arsenic already in the pigment to oxidize into pentavalent compounds, forming a thin white layer on the surface. Those findings are consistent with the analyzed samples taken from The Intrigue, confirming the degradation is due to photo-oxidation. Light, it turns out, is the greatest threat to that particular painting, and possibly other masterpieces from the same period.

Science Advances, 2025. DOI: 10.1126/sciadv.ady1807 (About DOIs).

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Neural network finds an enzyme that can break down polyurethane

AI, biochemistry, Biology, chemistry, enzymes, neural networks, polymers, polyurethane, protein design, proteins, Science / Tim Belzer / October 31, 2025

You’ll often hear plastic pollution referred to as a problem. But the reality is that it’s multiple problems. Depending on the properties we need, we form plastics out of different polymers, each of which is held together by a distinct type of chemical bond. So the method we use to break down one type of polymer may be incompatible with the chemistry of another.

That problem is why, even though we’ve had success finding enzymes that break down common plastics like polyesters and PET, they’re only partial solutions to plastic waste. However, researchers aren’t sitting back and basking in the triumph of partial solutions, and they’ve now got very sophisticated protein design tools to help them out.

That’s the story behind a completely new enzyme that researchers developed to break down polyurethane, the polymer commonly used to make foam cushioning, among other things. The new enzyme is compatible with an industrial-style recycling process that breaks the polymer down into its basic building blocks, which can be used to form fresh polyurethane.

Breaking down polyurethane

Image of a set of chemical bonds. From left to right there is an X, then a single bond to an oxygen, then a single bond to an oxygen that's double-bonded to carbon, then a single bond to a nitrogen, then a single bond to another X. — The basics of the chemical bonds that link polyurethanes. The rest of the polymer is represented by X’s here.

The new paper that describes the development of this enzyme lays out the scale of the problem: In 2024, we made 22 million metric tons of polyurethane. The urethane bond that defines these involves a nitrogen bonded to a carbon that in turn is bonded to two oxygens, one of which links into the rest of the polymer. The rest of the polymer, linked by these bonds, can be fairly complex and often contains ringed structures related to benzene.

Digesting polyurethanes is challenging. Individual polymer chains are often extensively cross-linked, and the bulky structures can make it difficult for enzymes to get at the bonds they can digest. A chemical called diethylene glycol can partially break these molecules down, but only at elevated temperatures. And it leaves behind a complicated mess of chemicals that can’t be fed back into any useful reactions. Instead, it’s typically incinerated as hazardous waste.

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The chemistry behind that pricey cup of civet coffee

chemistry, coffee, Food science, kopi luwak, Science / Kris Guyer / October 29, 2025

A sampling of scat

Kopi luwak is quite popular, with well-established markets in several South and East Asian countries. Its popularity has risen in Europe and the US as well, and India has recently become an emerging new market. Since there haven’t been similar studies of the chemical properties of kopi luwak from the Indian subcontinent, the authors of this latest study decided to fill that scientific gap. They focused on civet coffee produced in Kodagu, which produces nearly 36 percent of India’s total coffee production.

The authors collected 68 fresh civet scat samples from five different sites in Kodagu during peak fruit harvesting in January of this year. Collectors wore gloves to avoid contamination of the samples. For comparative analysis, they also harvested several bunches of ripened Robusta coffee berries. They washed the scat samples to remove the feces and also removed any palm seeds or other elements to ensure only Robusta beans remained.

For the manually harvested berries, the authors removed the pulp after a natural fermentation process and then sun-dried the beans for seven days. They then removed the hulls of both scat-derived and manually harvested berries and dried the beans in an oven for two hours. None of the bean samples were roasted, since roasting might significantly alter the acidity and chemical composition of the samples. For the chemical analysis, 10 distinct samples (five from each site where berries were collected) were ground into powder and subjected to various tests.

The civet beans had higher fat levels, particularly those compounds known to influence aroma and flavor, such as caprylic acid and methyl esters—contributing to kopi luwak’s distinctive aroma and flavor—but lower levels of caffeine, protein, and acidity, which would reduce the bitterness. The lower acidity is likely due to the coffee berries being naturally fermented in the civets’ digestive tracts, and there is more to learn about the role the gut microbiome plays in all of this. There were also several volatile organic compounds, common to standard coffee, that were extremely low or absent entirely in the civet samples.

In short, the comparative analysis “further supports the notion that civet coffee is chemically different from conventionally produced coffee of similar types, mainly due to fermentation,” the authors concluded. They recommend further research using roasted samples, along with studying other coffee varieties, samples from a more diverse selection of farms, and the influence of certain ecological conditions, such as canopy cover and the presence of wild trees.

Scientific Reports, 2025. DOI: 10.1038/s41598-025-21545-x (About DOIs).

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Breaking down rare earth element magnets for recycling

chemistry, rare earth elements, recycling, Science / Mike M. / October 20, 2025

All the world’s discarded phones, bricked laptops, and other trashed electronics are collectively a treasure trove of rare earth elements (REEs). But separating out and recovering these increasingly sought-after materials is no easy task.

However, a team of researchers says it has developed a way of separating REEs from waste—magnets, in this case—that is relatively easy, uses less energy, and isn’t nearly as emissions and pollution intensive as current methods. The team published a paper describing this method in the Proceedings of the National Academy of Sciences.

In short, this process involves using an electric current to heat waste magnets to very high temperatures very fast, and using chlorine gas to react with the non-REEs in the mix, keeping them in the vapor phase. James Tour, one of the authors and a professor of materials science and nanoengineering at Rice University, says that the research can help the United States meet its growing need for these elements.

“The country’s scurrying to try to see how we can get these [REEs],” he says. “And, in our argument, it’s all in our waste… We have it right here, just pull it right back out of the waste.”

Getting hot in here

In 2018, Tour and his colleagues discovered that this rapid heating process, called flash joule heating, can turn any carbon source—including coal, biochar, and mixed plastic—into graphene, a very thin, strong, and conductive material.

Building on this, in 2023, they developed a method that uses flash joule heating and chlorine. In this work, they identified the Gibbs free energy, the reactivity of a material, for the oxide form of all 17 REEs and nine common oxides found in REE waste.

Ground-up waste magnets are put on a platform made of carbon and surrounded by a glass chamber. A current runs through the platform, rapidly producing immense heat, thousands of degrees celsius in a matter of seconds. Chlorine gas is then released into the chamber, creating chlorides of unwanted elements like iron and lowering their boiling points.

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Chemistry Nobel prize awarded for building ordered polymers with metal

chemistry, chemistry Nobel, metal organic framework, nobel prizes, Science / Rejus Almole / October 8, 2025

Unlike traditional polymers, this structure allows MOFs to have open internal spaces with a well-defined size, which can allow some molecules to pass through while filtering out others. In addition, the presence of metals provides for interesting chemistry. The metals can serve as catalysts or preferentially bind to one molecule within a mixture.

Knowing what we know now, it all seems kind of obvious that this would work. But when Robson started his work at the University of Melbourne, the few people who thought about the issue at all expected that the molecules he was building would be unstable and collapse.

The first MOF Robson built used copper as its metal of choice. It was linked to an organic molecule that retained its rigid structure through the presence of a benzene ring, which doesn’t bend. Both the organic molecule and the copper could form four different bonds, allowing the structure to grow by doing the rough equivalent of stacking a bunch of three-sided pyramids—a conscious choice by Robson.

Image of multiple triangular chemicals stacked on top of each other, forming a structure with lots of open internal spaces. — The world’s first MOF, synthesized by Robson and his colleagues. Credit: Johan Jarnestad/The Royal Swedish Academy of Sciences

In this case, however, the internal cavities remained filled by the solvent in which the MOF was formed. But the solvent could move freely through the material. Still, based on this example, Robson predicted many of the properties that have since been engineered into different MOFs: the ability to retain their structure even after solvents are removed, the presence of catalytic sites, and the ability of MOFs to act as filters.

Expanding the concept

All of that might seem a very optimistic take for someone’s first effort. But the measure of Robson’s success is that he convinced other chemists of the potential. One was Susumu Kitagawa of Kyoto University. Kitagawa and his collaborators built a MOF that had large internal channels that extended the entire length of the material. Made in a watery solution, the MOF could be dried out and have gas flow through it, with the structure retaining molecules like oxygen, nitrogen, and methane.

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Betel nuts have been giving people a buzz for over 4,000 years

Archeology, betel nuts, Biology, chemistry, drugs, Science, stimulants / Rejus Almole / August 20, 2025

Ancient rituals and customs often leave behind obvious archaeological evidence. From the impeccably preserved mummies of Egypt to psychoactive substance residue that remained at the bottom of a clay vessel for thousands of years, it seems as if some remnants of the past, even if not all are immediately visible, have defied the ravages of time.

Chewing betel nuts is a cultural practice in parts of Southeast Asia. When chewed, these reddish nuts, which are the fruit of the areca palm, release psychoactive compounds that heighten alertness and energy, promote feelings of euphoria, and help with relaxation. They are usually wrapped in betel leaves with lime paste made from powdered shells or corals, depending on the region.

Critically, the ancient teeth from betel nut chewers are distinguishable because of red staining. So when archaeologist Piyawit Moonkham, of Chiang Mai University in Thailand, unearthed 4,000-year-old skeletons from the Bronze Age burial site of Nong Ratchawat, the lack of telltale red stains appeared to indicate that the individuals they belonged to were not chewers of betel nuts.

Yet when he sampled plaque from the teeth, he found that several of the teeth from one individual contained compounds found in betel nuts. This invisible evidence could indicate teeth cleaning practices had gotten rid of the color or that there were alternate methods of consumption.

“We found that these mineralized plaque deposits preserve multiple microscopic and biomolecular indicators,” Moonkham said in a study recently published in Frontiers. “This initial research suggested the detection potential for other psychoactive plant compounds.”

Since time immemorial

Betel nut chewing has been practiced in Thailand for at least 9,000 years. During the Lanna Kingdom, which began in the 13th century, teeth stained from betel chewing were considered a sign of beauty. While the practice is fading, it is still a part of some religious ceremonies, traditional medicine, and recreational gatherings, especially among certain ethnic minorities and people living in rural areas.

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This aerogel and some sun could make saltwater drinkable

aerogel, chemistry, desalina, desalination, materials science, Science, solar power / Rejus Almole / July 26, 2025

Earth is about 71 percent water. An overwhelming 97 percent of that water is found in the oceans, leaving us with only 3 percent in the form of freshwater—and much of that is frozen in the form of glaciers. That leaves just 0.3 percent of that freshwater on the surface in lakes, swamps, springs, and our main sources of drinking water, rivers and streams.

Despite our planet’s famously blue appearance from space, thirsty aliens would be disappointed. Drinkable water is actually pretty scarce.

As if that doesn’t already sound unsettling, what little water we have is also threatened by climate change, urbanization, pollution, and a global population that continues to expand. Over 2 billion people live in regions where their only source of drinking water is contaminated. Pathogenic microbes in the water can cause cholera, diarrhea, dysentery, polio, and typhoid, which could be fatal in areas without access to vaccines or medical treatment.

Desalination of seawater is a possible solution, and one approach involves porous materials absorbing water that evaporates when heated by solar energy. The problem with most existing solar-powered evaporators is that they are difficult to scale up for larger populations. Performance decreases with size, because less water vapor can escape from materials with tiny pores and thick boundaries—but there is a way to overcome this.

Feeling salty

Researcher Xi Shen of the Hong Kong Polytechnic University wanted to figure out a way to improve these types of systems. He and his team have now created an aerogel that is far more efficient at turning over fresh water than previous methods of desalination.

“The key factors determining the evaporation performance of porous evaporators include heat localization, water transport, and vapor transport,” Shen said in a study recently published in ACS Energy Letters. “Significant advancements have been made in the structural design of evaporators to realize highly efficient thermal localization and water transport.”

Solar radiation is the only energy used to evaporate the water, which is why many attempts have been made to develop what are called photothermal materials. When sunlight hits these types of materials, they absorb light and convert it into heat energy, which can be used to speed up evaporation. Photothermal materials can be made of substances including polymers, metals, alloys, ceramics, or cements. Hydrogels have been used to successfully decontaminate and desalinate water before, but they are polymers designed to retain water, which negatively affects efficiency and stability, as opposed to aerogels, which are made of polymers that hold air. This is why Shen and his team decided to create a photothermal aerogel.

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