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Spectroscopic OCT plus AI detects high-risk plaque in coronary arteries

AI-based OCT detection of lipid-rich plaque
Detecting fatty deposits Left: intravascular OCT image with lipid-rich plaque; centre: AI-generated lipid map overlay (red areas indicate higher lipid likelihood); right: ground truth (tissue staining section). The AI-identified lipid regions matched well with histopathology results. (Courtesy: Hyeong Soo Nam, KAIST)

Identifying lipid-rich plaques inside coronary arteries is critical to assess a patient’s risk of having a heart attack. These fatty deposits adhere to the walls of blood vessels and, if they rupture, can trigger adverse cardiovascular events.

Currently, physicians use near-infrared spectroscopy and intravascular ultrasound (NIRS-IVUS) to quantitatively assess plaque lipid burden. Optical coherence tomography (OCT) is another intravascular imaging modality used during catheter-based procedures and provides micrometre-resolution visualization of plaque structure. But its diagnostic accuracy is limited by imaging artefacts and signals originating from non-lipid plaque components.

Researchers in Korea are developing a different approach: combining the biochemical specificity of spectroscopic OCT (S-OCT) with artificial intelligence (AI). This combination enables automated, composition-aware tissue characterization, and offers interpretable and annotation-efficient lipid mapping.

“By enabling efficient lipid screening and spatial interpretation, [the technique] establishes a scalable foundation for downstream assessment of lipid burden and clinically relevant plaque characterization, with potential utilization for automated risk stratification,” the researchers explain in Biomedical Optics Express.

Model training and validation

The AI-enhanced S-OCT system, which utilizes existing OCT systems without requiring hardware modification, incorporates an AI model developed by researchers at the Korea Advanced Institute of Science and Technology (KAIST) and the Multimodal Imaging and Theranostic Lab of the Korea University Guro Hospital. The AI model receives wavelength-dependent information from the OCT images and, by recognizing signal patterns associated with lipid-rich tissue, automatically highlights any suspicious regions in the image.

Team leader Hyeong Soo Nam from KAIST and collaborators created a dataset to train the AI model, using 848 lipid-positive and 622 non-lipid frames acquired from images of five rabbits with induced atherosclerotic plaques. They manually annotated each OCT frame to indicate lipid presence, and employed complex calibrated interferometric signals obtained through standard OCT processing to extract depth-resolved spectroscopic information for S-OCT. Finally, they applied a vessel region selection procedure with a depth range selected to focus the analysis on biologically relevant vessel regions with potential lipid content.

After training the deep-learning model, the researchers evaluated its performance in classifying lipid presence and spatial localization of lipid-associated regions, on both lipid-positive and non-lipid image frames. They also conducted histopathological validations to validate the predictions against ground truth, and compared the performance of the trained S-OCT model with an identically trained greyscale OCT-only model to assess the benefit of incorporating spectroscopic identification.

When assessing the relative importance of distinct spectral regions for lipid detection, the researchers discovered that training the model on a short-wavelength spectral subset (below 1300 nm) resulted in a higher lipid localization Dice score (a similarity metric) than a model trained on the long-wavelength band (above 1300 nm).

“This performance difference suggests the network relies more on spectroscopic features in the short-wavelength region, where lipid absorption shows a more pronounced spectral gradient,” they write. “The superior performance with short-wavelength data implies that the model effectively utilizes this spectral gradient, rather than relying on shared morphological features, to enhance lipid detection.”

The researchers validated their approach by imaging two rabbits with atherosclerotic plaques, and comparing the AI-generated predictions against histopathology results using lipid-specific tissue staining. The proposed model accurately localized lipid regions with strong spatial correspondence to histology, achieving a lipid localization Dice score of 83.9%.

“The results showed strong classification performance along with good spatial agreement with the pathological findings,” says Nam in a press statement. “By analysing wavelength-dependent information hidden in the OCT signal and combining it with AI, we were able to identify the presence and distribution of lipids within the vessel wall.”

“During a coronary intervention, this method could provide clinicians with additional information to support risk assessment, procedural planning and evaluation of treatment response,” Nam emphasizes. “Ultimately it has the potential to contribute to safer clinical decision making, more individualized treatment strategies and improved long-term management of patients with coronary artery disease.”

The team is currently working to improve the processing speed and robustness of their approach to make it more practical for real-time clinical use, and plan to perform validation studies using data from human coronary arteries. In addition, they aim to create a seamless method for integrating data reporting (the presence or absence of lipid plaque) into the clinical workflow.

Rocket re-entry pollutes the upper atmosphere

Thanks to new resonance lidar measurements, researchers in Germany, the UK and Peru have successfully measured and traced a lithium plume created by a rocket stage as it uncontrollably re-entered and broke up in the upper atmosphere. The work represents the first time that upper-atmospheric pollution from space debris re-entry has been directly detected, they say. Such pollution is a growing concern and is only likely to worsen as more and more satellites are being launched into space, and in particular into low-Earth orbit.

The number of satellite and rocket launches has increased dramatically over the last decade and this number is set to increase as ever more commercial mega-constellations are deployed. For example, the Starlink constellation is planned to consist of over 40 000 satellites, each with a mass of between 305 and 960 kg. Given their typical operational lifetimes of five years, these satellites are expected to re-enter Earth’s atmosphere through uncontrolled decay within the next several years.

Previous studies in this domain have mainly focused on the dangers of space debris falling to the ground, but we still know little about the environmental effects that the debris can have on our atmosphere. We do know, however, that the upper atmosphere is today host to many exotic atomic and molecular species that cannot be explained as having naturally come from meteors. This is worrying since the upper atmosphere is crucial for shielding life on Earth from meteoroids and UV radiation.

An intense fireball

At roughly 03:42 UTC on 19 February 2025, the upper stage of a SpaceX Falcon 9 rocket uncontrollably re-entered the atmosphere at an altitude of around 100 km, off the western coast of Ireland. This event produced an intense fireball that many people (and radar systems) were witness to, as well as a persistent high-altitude plume of lithium vapour. It also made headline news when fragments of the debris, including a fuel tank, were recovered near Poznań in Poland.

A team of researchers led by Robin Wing of the Leibniz Institute of Atmospheric Physics in Germany measured the concentration of lithium atoms in the mesosphere (which lies between 50 and 85 km in altitude) and the lower thermosphere (between around 85 and 120 km in altitude). They detected the lithium plume in the latter, using a resonance fluorescence lidar in Kühlungsborn in Germany. They also used locally measured winds from the SIMONe Germany meteor radar and global winds from the Upper Atmosphere ICON (UA-ICON) model to determine the path the lithium plume took and where it had originated.

Lidar is a laser-based remote sensing instrument that can be used to measure conditions in the atmosphere. The researchers chose to focus on lithium because it is routinely employed in spacecraft components, such as lithium-ion batteries and lithium-aluminium (Li-Al) alloy hull plating, but it is only naturally present in trace amounts at the altitudes studied. The flux of natural lithium (which comes from meteoric sources) is estimated to be around 80 g per day, while the amount of lithium contained in a single rocket stage is about 30 kg. This large disparity therefore makes lithium a sensitive tracer of man-made input from space debris re-entries, explain the researchers.

Vaporization of lithium begins at approximately 98 km altitude

Scientists already know that lithium rapidly vaporizes when a Li-Al structure ablates and it appears in the atmosphere as the aluminium matrix melts at 933 K. In their work, Wing and colleagues estimated the altitudes at which a Li-Al hull will begin to melt using the Leeds Chemical Ablation Model. For the hull thickness of the Falcon 9, they expect melting and vaporization of lithium to begin at approximately 98 km.

The strong atomic resonance fluorescence line of lithium at 670.7926 nm allows lidar to detect very trace amounts of lithium, both in the mesosphere and lower thermosphere. This enabled the researchers to perform altitude- and time-resolved measurements of the amount of lithium during and after re-entry events. Thanks to their measurements during six hours on the night of 19-20 February, they detected a sudden increase in the signal at about 96 km altitude, by a factor of 10 from the baseline value, just after midnight UTC on 20 February.

The results from this work, which is detailed in Communications Earth & Environment, also back up a recent study of the lower stratosphere conducted by Daniel Murphy at the NOAA and colleagues, which attributed significant middle-atmospheric pollution to space debris.

Potential harm to the ozone layer

Analysing the impact of re-entering space debris on the atmosphere is quite new, says Wing. “The paper by Murphy and colleagues, which was published in 2023, showed that 10% of stratospheric aerosols are already contaminated by materials from space debris. This previous work really motivated us to build a lidar capable of measuring what is left behind when rockets or satellites disintegrate in the atmosphere.”

The primary concern surrounding how space debris impacts the atmosphere is currently potential harm to the ozone layer, he tells Physics World. “Our work shows that we can now measure emissions from re-entering space objects and can use winds from radar observations and models to identify potential sources. By applying similar or improved setups to ours around the globe, the scientific community could provide the space industry with solid findings so we can all optimize the use of space.”

The researchers say they are now working on building a new and improved system to measure lithium and sodium. “We would also like to conduct the first survey of various metals such as copper, titanium and lead in the atmosphere that could be connected to space debris,” says Wing.

Academic collaboration with industry is no longer optional – it is now essential

Anyone paying even cursory attention to the research landscape in recent months would have noticed the growing turbulence in public science funding on both sides of the Atlantic. In the UK, the research community has been shaken not by a single dramatic cut, but by a prolonged period of budgetary tightening at UK Research and Innovation (UKRI), driven by flat-cash settlements, rising inflation and increasing pressure to redirect funding towards government-defined missions.

Although government ministers continue to emphasize “record” overall R&D spending, UKRI has been forced to make difficult reprioritization decisions, leading to pauses and closures of several schemes across the research councils. The effects are already being felt, with competition for remaining funding intensifying. Success rates are coming under strain and many researchers are facing heightened uncertainty about the viability of pursuing curiosity-driven research.

Globally, the picture is similar. In the US, the National Science Foundation has become a focal point of intense budgetary uncertainty, with proposed reductions and flat-cash congressional settlements placing growing strain on its ability to sustain investigator-led research. In Europe the €95.5bn Horizon Europe programme faces mounting political pressure to demonstrate impact and value for money amid economic uncertainty and competing fiscal priorities.

For academics, these dynamics translate into tougher competition for grants, longer odds of success and an increasing reliance on short-term, project-specific funding rather than stable, long-horizon research support.

Academic science has always been under pressure to deliver more with less. But the current climate feels different. The combination of shrinking government budgets, rising operational costs and increasing competition for limited grants has created a perfect storm. For early-career researchers and established labs alike, the traditional model of securing public funding is becoming unsustainable.

The implications are profound. Without adequate resources, research groups risk losing momentum, empty talent pipelines and stalling innovation. For many the question is no longer “how do we grow?” but “how do we survive?” Yet amid these challenges lies an opportunity: forging deeper, more strategic partnerships with industry.

The path ahead

You may ask the question “why would companies invest in academic research?” The answer is simply innovation. Industry thrives on differentiation and academic partnerships offer a cost-effective way to access cutting-edge science without bearing the full burden of in-house R&D.

Consider the pharmaceutical sector. Drug discovery is notoriously expensive and time-consuming but collaborating with academic labs allows companies to tap into specialized expertise, advanced facilities and novel methodologies. Similarly in energy and materials science, universities often lead the way in developing next-generation technologies that can redefine markets.

Beyond innovation, partnerships also offer credibility. Peer-reviewed publications and independent validation enhance a company’s reputation and can accelerate regulatory approval. For industries facing complex challenges; such as sustainability, cybersecurity or quantum computing, academic collaboration is not a luxury; it’s a necessity.

So, what can be done to strengthen academic collaboration with industry? The first step is a subtle but important mindset shift. For many researchers, academia has traditionally operated with a strong internal focus, where industry engagement is seen less as undesirable and more as additional – something that sits alongside core research rather than at its centre.

This isn’t about viewing collaboration as secondary or compromising, but about recognizing that aligning fundamental research with industry priorities takes time and sustained effort. It introduces new constraints, different timelines and added complexity into already demanding research programmes.

The challenge, then, is not one of principle, but of practicality. Collaboration is not about box-ticking or “selling out”; it’s about creating the conditions in which fundamental research can remain connected, impactful and resilient in an increasingly complex research ecosystem.

Academics should look for companies with long-term goals that align with their research expertise – creating shared value, not just chasing sponsorships. Another aspect to remember is that industry mandates tangible outcomes. While fundamental research remains vital, framing projects in terms of applied benefits can unlock funding.

It is also important that academics learn to communicate impact. Industry leaders speak the language of “minimum viable product”, “return on investment” and “risk mitigation”. Academics must learn to articulate how their work translates into competitive advantage.

This mindset shift requires effort, but the payoff can be significant in sustained funding streams, access to real-world data, as well as opportunities to test theories in practical settings. When done right, such collaborations also create a virtuous cycle. Academics secure funding and maintain research momentum, while industry gains competitive advantage, joint publications, shared intellectual property and co-developed technologies that strengthen both ecosystems.

Such partnerships can also foster talent development. Graduate students and postdocs gain exposure to realistic problems, enhancing employability and bridging the gap between theory and practice – a critical outcome, given the current bleak outlook for graduate employment worldwide.

For industry, this means access to a pipeline of skilled professionals who understand both scientific rigor and commercial realities. The benefits also extend beyond economics. Collaborative projects often tackle grand challenges – climate change, healthcare, digital security – that no single entity can solve alone. By pooling resources and expertise, academia and industry can drive progress at a scale that matters.

An industrial collaboration ‘playbook’

Mark Procter outlines his five principles for building successful partnerships between academia and industry.

1 Align on impact, not just intellectual property

Focus on creating measurable outcomes rather than solely on rigid intellectual property battles. Impact drives funding and reputation for both sides.

2 Define mutual gains early

Establish clear objectives that benefit both academic advancement and industrial innovation. Document these in a collaboration charter before work begins.

3 Streamline governance

Simplify legal frameworks and reduce administrative friction. Negotiating non-disclosure and intellectual property agreements should not take longer than the research itself.

4 Embed talent exchange

Include opportunities for student placements, joint supervision and secondments. This builds trust and creates a pipeline of skilled professionals. Reciprocally, universities should structure their own professional development opportunities in collaboration with industry.

5 Measure success beyond publications

Track metrics such as technology readiness progression, prototype development and demonstrable economic impact, not just journal citations.

To make this vision a reality, collaboration must be incentivized. Funding agencies can play a pivotal role by enabling grants that include industrial partners, while tax incentives for collaborative R&D could further accelerate uptake.

At the same time, universities must embrace cultural change. Academics must move beyond the notion that collaboration dilutes scientific integrity. Transparency and clear governance can safeguard independence while enabling impact.

The future of academic science may well depend on its ability to align with industry. The current rhetoric from UKRI focuses on return on investment from publicly funded research to meet the UK’s industrial strategy.

In a world where resources are scarce and challenges are complex, working together is the only way forward. The coming decade will test the resilience of academic research. Those who cling to old models risk obsolescence. Those who adapt by embracing industry partnerships will not only survive but thrive. The question is not whether collaboration is necessary, but how quickly we can make it happen.

Could lightning occur on Mars?

Researchers in the Czech Republic say they may have observed the signature of a “whistler” in a one-second snapshot captured by the MAVEN probe orbiting Mars. The event, observed in the ionosphere of the planet, would be the first lightning-like electric discharge activity ever to be seen there and the finding will be important for understanding atmospheric processes in the Martian atmosphere.

“Whistlers are well known on Earth and are associated with lightning,” explains space physicist František Němec at Charles University, who led this research effort. “Our result implies that this phenomenon also occurs on our planetary neighbour.”

Unlike Earth, Mars does not have a global magnetic field, but only localized fields created by magnetized materials in the planet’s crust. And because its atmosphere is thin, lightning on this planet does not originate in water clouds but instead in dust storms, similar to those observed in volcanic eruptions here on Earth, and in dust devils.

During dust storms, dust grains become electrically charged as they collide with each other and generate an electric field. On Mars, previous studies have predicted that this field can discharge when its value exceeds the breakdown threshold in the low-pressure Martian atmosphere, which is around 15 kV/m.

Dust devils, for their part, can produce ultralow-frequency radiation on Earth thanks to the electrical charges that fluctuate as the dust swirls around. Since both dust devils and dust storms are much stronger on Mars, theory suggests that they could generate wideband radiation that we could detect on Earth. Despite recent measurements by the Allen Telescope Array, the Mars Global Surveyor (MGS) and Mars Atmosphere and Volatile Evolution (MAVEN) missions and the Mars Express spacecraft, conclusive evidence for Martian lightning has yet to be found.

Analysing electromagnetic radiation

Another way to detect these electric discharges, says Němec, is to analyse the electromagnetic radiation that accompanies them. This radiation lies in the extremely low frequency/very low frequency range and, under some conditions, can reach the ionosphere of a planet. The phenomenon was first identified and observed on Earth shortly before the space era and such electromagnetic waves have successfully been used to provide evidence for lightning on Jupiter, Saturn and Neptune since then.

These waves are known as whistlers, he explains, because of their characteristic spectral pattern in the plasma medium of the ionosphere. Here, higher frequency waves propagate faster and arrive at the observation point sooner than lower frequency ones, resulting in a characteristic “whistling” spectral shape.

The observational challenge is that these waves can penetrate the Martian ionosphere only on the nightside of the planet and when the magnetic field is pointing in the vertical direction. This largely restricts the areas over Mars which whistlers can be observed by spacecraft – namely, to the relatively small crustal field regions in the southern hemisphere of the planet.

Němec says he has now identified the electromagnetic wave signature of a whistler on Mars in a snapshot captured by the MAVEN probe on 21 June 2015. “I first identified it at night in a region with a strong and nearly vertical magnetic field, something that is crucial for the wave to be able to propagate to the altitude of where the probe is orbiting without its signal attenuating too much.”

Out of the many wave snapshots analysed (108,418 in total), only this single event contained a whistler signature, he tells Physics World. “This likely reflects the rarity of the phenomenon itself, as well as the specific ionospheric and magnetic field conditions required for the wave to propagate all the way to the spacecraft.”

The MAVEN probe has been orbiting Mars since 2014 and sent back data to Earth until we lost communication with it last year. While no large-scale dust storms were recorded on the planet at the moment at which the probe captured the whistler, Němec and colleagues say the effect might have come from a local dust event.

Different propagation speeds

“Whistlers are formed because, in the ionized plasma of the ionosphere, different signal frequencies propagate at different speeds,” explains Němec. “As a result, although all frequencies are generated simultaneously during a lightning discharge, the higher frequencies – which propagate faster – arrive at the spacecraft first, followed later by the lower frequencies.”

The researchers, who detail their work in Science Advances, calculated these corresponding time delays and say that their observations agree “very well” with theoretical predictions. They also calculated how the waves attenuate by adapting methods used for Earth to the assumed composition of the Martian ionosphere. The results revealed that higher frequencies are more strongly attenuated, which explains why only the lower-frequency portion of the whistler is observed, says Němec.

The existence of strong lightning-like electrical discharges in the Martian atmosphere highlights the need to better understand the relevant atmospheric processes on the Red Planet, with a particular focus on dust storms and dust devils, he adds. The sudden energy release accompanying such discharges also clearly has the potential to locally alter the atmospheric chemistry.

The Charles University researchers together with their colleagues at the Institute of Atmospheric Physics say they are now working on a detailed analysis of how waves attenuate as they propagate through Mars’ ionosphere. “Importantly, we are actively involved in the design and development of the European Space Agency’s M7 mission candidate M-MATISSE,” reveals Němec. “This two-spacecraft mission, scheduled for launch in 2037, would feature advanced instrumentation for, among other things, wave measurements, and would allow for more detailed investigations of the relevant phenomena.

“We are very excited about this opportunity and hope that the mission will ultimately be adopted.”

Is ‘vibe physics’ the future?

At the American Physical Society’s Global Physics Summit in Denver, a session on “Navigating the AI revolution: future-proofing your science career” drew in a crowd of early-stage physicists searching for practical career advice. What they received was much more philosophical in nature.

Malachi Schram of the Pacific Northwest National Lab and Hilary Egan of the National Laboratory of the Rockies delivered back-to-back talks full of similar rhetoric, emphasizing the fast-paced development of AI used for specialized tasks in science, such as detecting equipment failure or identifying ways of retrofitting older buildings.

But the third speaker, Matthew Schwartz, a theoretical physicist from Harvard University, took his optimism about AI far further. In a punchy presentation, he predicted that large language models (LLMs) will surpass human intelligence in five years.

“There’s definitely exponential growth of the intellectual capacity of these [large language] models as a function of time,” Schwartz told the audience, using the number of model parameters as a proxy for intelligence. “The machines are still growing by roughly 10 times each year, and we” – he paused for dramatic effect – “are not growing much smarter.” This drew a wave of laughter from the crowd.

Unlike humans, machines can visualize higher dimensional spaces, hold far more information in memory and process more complex equations. “We are not the endpoint of intelligence. We are only the smartest things to evolve on Earth so far,” Schwartz argued. He went on to suggest that humans may simply be incapable of understanding long-standing physics problems such as a theory of everything. He compared it to cats, which he suggested will never understand chess.

If the talent of physicists exists on a bell curve, Schwartz claimed we can push the bell curve higher on the talent axis: “If we use AI augmentation, we can get 10,000 Einsteins a century instead of one Einstein.”

Opposing views

The next speaker after Schwartz was Matthew Ginsberg from Google Deepmind. Speaking in a personal capacity, he expressed strong disagreement over AI’s ability to advance physics. “Asking questions is the essence of being a good physicist, and this is, at least so far, 100% our domain,” he argued. In a direct response to Schwartz, Ginsberg added, “We aren’t being eaten away at exponentially. No, asking good questions is us. It’s what we’re good at.” He concluded, “I remain hopeful that we have a role to play.”

In his talk, Ginsberg emphasized the importance of human creativity. “LLMs generate the consensus response to hard questions,” he said. “You are the best physicist when you give the not consensus answer, which is what AI is incapable of doing.”

In a concluding panel discussion, the four experts seemed to converge on the idea that the human contribution to physics has to do with what some called “taste,” others “creativity,” or “asking good questions” (seemingly, questions that humans find interesting). However, over the three-hour session, Schwartz and Ginsberg independently predicted that AI may develop the ability to ask good questions in the next decade.

If so, this could undermine the main argument for the value of humans in science. So, does there exist a deeply human role in the physics of the future, or is “vibe physics” on the 10-year horizon? Perhaps only time will tell.

Extracting entropy information from quantum dots

Researchers have succeeded in measuring how energy dissipates in quantum dots by quantifying the entropy they produce. The work, by a team at Stanford University in the US, could help in the optimization of real-world nanoscale devices used in applications such as quantum memories and information processing.

Technologies like memory storage devices and information processors are intrinsically dissipative, explains materials scientist and engineer Aaron Lindenberg, who led this new study. Energy is lost as heat in many ways but at a fundamental level, this arises from the Landauer principle, which defines a lower limit for these energy costs. “When physical or computational processes evolve non-quasi-statically – for example, over a finite amount of time and out-of-equilibrium, the energy costs increase. Despite its fundamental and practical importance, directly measuring this dissipation remains extremely challenging, particularly as modern devices continue to shrink in size.”

In the new work, Lindenberg and colleagues wanted to measure energy dissipation directly in real materials in contrast to previous experiments that measured entropy production in very clean systems, such as defect centres in diamond. “Previously studied materials behaved like simple two-state ‘Markov’ systems, where the probability of moving to the next step is determined only by the current state,” explains Lindenberg, “but real materials often have memory effects and hidden internal states.

Good test systems

Quantum dots, which are tiny semiconductor crystals that emit fluorescent light when excited with ultraviolet light, are good test systems in this context, he says. When they emit light, charge carriers (electrons and holes) can tunnel into nearby defect states, temporarily stopping the emission, causing the quantum dot to “blink” between bright and dark states. This non-Markovian and stochastic blinking follows statistical patterns (a power law waiting-time distribution) that hint at memory effects and hidden states.

In their experiment, Lindenberg and colleagues in the School of Engineering and Photon Science at the SLAC National Accelerator Laboratory kept the ultraviolet excitation on continuously and switched an additional strong laser field on and off. This process changed the blinking statistics and drove the system out-of-equilibrium. The researchers then recorded the fluorescence blinking traces and used machine learning to optimize a physics-based “hidden Markov model”. “This allowed us to reconstruct the hidden state trajectories that are Markovian and then compute entropy production from them,” says Yuejun Shen, the first author of the study, which is detailed in Nature Physics.

Entropy production of quantum dots is a quantity that describes how reversible a microscopic process. It encodes information about memory, information loss (as the distribution of charge carriers in the dots evolves) and energy dissipation. Such measurements therefore enable new possibilities for determining the ultimate efficiency limits of a device, he explains.

Measuring entropy production

Lindenberg adds that the new work provides a general method to measure entropy production in complex, stochastic and non-equilibrium systems in which we cannot observe all internal states directly.

While practical applications may still be a way off, the approach could eventually help measure and reduce dissipation in nanoscale devices, he tells Physics World. “This is especially important as device sizes continue to shrink and stochastic fluctuations become unavoidable.”

As to future work, the Stanford researchers say they would now like to measure energy dissipation in other material systems and implement optimization algorithms to minimize this dissipation. “This new type of calorimetry could have applications in many other types of information storage devices and technologies,” says Lindenberg.

Rechargeable liquid solar battery stores sunlight in molecules

Being able to store renewable energy, such as that produced by sunlight, so that it can be used at night or on cloudy days remains a major challenge. In recent years, researchers have been looking into molecular solar thermal (MOST) energy storage systems that harness the energy from photons and release it when needed. Now, a joint US team from Grace Han’s lab at the University of California, Santa Barbara, and Kendall Houk’s lab at the University of California, Los Angeles, has published details of a bio-inspired pyrimidone-based molecule that, when highly strained, stores a record amount of photon energy in its chemical bonds. The energy released when the molecule is allowed to relax is enough to boil water, the researchers say.

The structure of pyrimidone looks very much like that of a component found in DNA, which, when exposed to ultraviolet light, can reversibly form “Dewar lesions”. “These lesions naturally contain significant ring strain, something that immediately stood out to us as a promising feature for energy storage,” says first author Han Nguyen.

The researchers set out to engineer a synthetic version of this structure, the Dewar isomer of pyrimidone, which they also designed to be highly strained. They did this by combining a de-aromatization strategy with a compounded strain effect from fusing two already strained rings contained within the molecule.

Better than previous MOST energy storage systems and Li-ion batteries

“As a result, each molecule can store a large amount of energy, reaching 228 kJ/mol,” says Nguyen. “This translates to a gravimetric energy density of 1.6 MJ/kg, a value that is at least 1.6 times higher than previous MOST energy storage systems and nearly double the energy density of a standard lithium-ion battery (around 0.9 MJ/kg).”

The system can be described as a mechanical spring, she says. “When hit with sunlight, it twists into a strained, high-energy shape. It stays locked in that shape until a trigger – such as a small amount of heat or a catalyst – snaps it back to its relaxed state, releasing the stored energy as heat. It can be thought of as a liquid solar battery that stores sunlight and can be recharged.”

The result, Nguyen explains, addresses a long-standing limitation of MOST materials: insufficient energy density for practical use. Until now, the stored heat could only be released and used in well-insulated environments to minimize losses. “In contrast, our system releases enough heat to operate under ambient conditions and in our demonstrations, the heat output is strong enough to boil a sample of 0.5 mL of water in under one second.”

According to the researchers, the study “marks an important step toward real-world applications and shows that MOST systems can now move beyond controlled laboratory settings and function robustly in practical environments”.

A simplified structure that is soluble in water

This pyrimidone system had not been explored before as a candidate for MOST materials, so the researchers first had to design a simplified structure based on the Dewar lesion. The challenge, remembers Nguyen, was to strip away parts that were not relevant to the application in hand while retaining the features responsible for efficient storage and release of energy. “Through iterative design and testing, we arrived at a structure that is both efficient and practical,” she says.

Another challenge was improving functionality. “Our early designs still required solvents, which limit practical use,” she explains. “To solve this, we engineered the system into a liquid-state molecule that can operate without solvent.”

The fact that the material is soluble in water means that it could be pumped through roof-mounted solar collectors to charge during the day and stored in tanks to provide heat at night, adds team member Benjamin Baker. “With solar panels, you need an additional battery system to store the energy, but with molecular solar thermal energy storage, the material itself is able to store that energy from sunlight.”

The UCSB researchers hope their work, which they detail in Science, will encourage further research in the field, so that pyrimidone and other heterocycles like it can be further improved and optimized. “We would like to design and develop molecules that absorb in a broader range of solar radiation,” says Houk. “We also want to maintain high energy density, thermal stability and energy release upon thermal ring opening and will use quantum mechanical calculations to make these predictions.”

To this end, he adds, the team plans to screen hundreds to thousands of molecules, perhaps with AI assistance, to open up new avenues for experimental research.

Nguyen tells Physics World that the goal of her laboratory is “to make heat more affordable and accessible, especially in situations where people need it most. For example, our materials could be useful in emergency or disaster settings where access to power and fuel is limited”.

Looking further ahead, she says that the technology could be integrated into real-world systems, such as heating for houses and buildings, helping to provide more reliable and accessible heat in everyday life.

The coming hurricane: early-career physicists and the crisis in American science

With several dozen talks taking place at any one time, figuring out which session to attend at the American Physical Society’s Global Physics Summit is a challenge. On Wednesday, though, my choice was particularly stark. Should I depress myself by attending the session on “The Crisis in American Science”? Or restore my faith in humanity by finding out “How Early-Career Physicists Are Solving Society’s Greatest Challenges”?

A quirk of scheduling – or an APS organizer with a dark sense of humour – meant that the two sessions were practically next door to each other in Denver’s Colorado Convention Center. So, after a bit of dithering, I decided to oscillate between the two, hoping to strike a balance between cheer and gloom.

Reasons to be cheerful

The first speaker in the early-career physicists session was Rosimar Rios-Berrios, a physicist-turned-atmospheric-scientist at the US National Center for Atmospheric Research (NCAR). Located up the road from Denver in Boulder, Colorado, NCAR’s iconic, adobe-style Mesa Laboratory was designed by the architect I M Pei, and it supports the work of several hundred scientists who study weather and climate.

Rios-Berrios is originally from the US island territory of Puerto Rico, and her APS talk focused on a weather phenomenon that’s hugely important for anyone living on tropical islands or coasts: hurricanes. Rios-Berrios is trying to understand how these storms develop. In particular, she wants to know what happens in the atmosphere to cause gentle Caribbean breezes and fluffy white clouds to morph into devastating hurricanes like 2017’s Hurricane Maria, which killed nearly 3000 people in Puerto Rico alone, or 2025’s Hurricane Melissa, which devastated parts of Jamaica.

In previous studies, a specific type of atmospheric wave called a convectively coupled Kelvin wave had emerged as a possible hallmark of incipient tropical cyclones (a generic term for hurricanes and their Pacific Ocean equivalents, typhoons). These waves appear in the region near the equator where northeast and southeast trade winds meet, and they move eastward at around 15-20 metres per second, with wavelengths of 7000 km.

As they travel, the Kelvin waves perturb local concentrations of moisture, and their passing heralds a change in the direction of the prevailing winds. The resulting “zonal wind anomalies” are thought to play a role in spawning early-stage tropical cyclones. Observational data support this idea: two days after these waves pass through an area, there’s a noticeable uptick in tropical cyclones.

Rios-Berrios decided to investigate this correlation by developing an idealized model that captures the convective dynamics of both Kelvin waves and tropical cyclones. To simplify things, she based her model on an “Earth-like “aquaplanet” that lacks land and sea ice, and where temperatures vary only with latitude, and never with longitude or the passage of the seasons.

Despite these simplifications, Rios-Berrios found that this watery model world nevertheless produces hurricane-like swirls of wind and cloud. And after observing the full life cycle of more than 100 simulated tropical cyclones, she concluded that Kelvin waves do, in fact, influence their formation, with a two-day time lag that corresponds well to the data. “These results could help forecast active tropical cyclone periods several weeks in advance,” Rios-Berrios told the APS audience.

A gathering storm

Fortified by this promise, I picked up my laptop and walked the short distance to the “science crisis” session down the hall. I missed the session’s first talk, which aimed to draw comparisons between the Trump administration’s cuts to the National Science Foundation and the 1990s round of belt-tightening that doomed the Superconducting Super Collider project. However, I arrived in time for the second talk, in which a science historian, Zuoyue Wang, was scheduled to discuss parallels between the current situation and a succession of Cold War-era science budget crises.

To my surprise, Wang’s first slide featured a photo of NCAR’s iconic Mesa Lab – but not because of the great work being done there by Rios-Berrios and her colleagues. The fact that NCAR studies climate as well as weather means it has fallen foul of MAGA Republicans’ denial of climate change. In December 2025, the Trump White House issued a memo specifically targeting the centre and claiming that “NCAR’s activities veer far from strong or useful science”.

As a consequence of this disfavour, Wang told the audience, “NCAR is being dismantled as we speak.” Though some members of the US Congress have pushed back against the administration’s cuts, Wang described the attacks on science as “never-ending”.

By the end of Wang’s talk, all the optimism I’d built up in hearing about Rios-Berrios’ efforts to protect people from tropical cyclones was blasted from its foundations. If this is the kind of science the current US regime deems “useless”, I wondered, what on Earth is going to happen to the rest of the work on show at events like the APS Summit?

From the classroom to the committee room: Dave Robertson MP on politics and physics

This episode of the Physics World Weekly podcast features a conversation with Dave Robertson, who was elected member of the UK parliament for Lichfield in 2024. Robertson spent eight years teaching physics after studying the subject at the University of Liverpool. He then worked for a teachers’ union, which inspired him to become a candidate for the Labour Party.

He chats with Physics World’s Matin Durrani about his transition from the classroom to the committee room and how parliament “is a truly bonkers and truly bizarre workplace”.

Robertson has already sponsored three physics-related events at the Palace of Westminster and he talks about his membership of various cross-party parliamentary groups – including those on nuclear energy and space.

Robertson has not forgotten his roots in education and is adamant that the UK must address its nationwide shortage of physics teachers. He also urges physicists to speak out about how they can help address many of the world’s problems, notably climate change.

Geometry induces chirality in nickel – and magnons flow

The ability to control the direction in which a signal travels – without external switching, without added circuitry – is a longstanding goal in the design of compact magnetic devices. Magnetochiral anisotropy offers exactly that: a material-level asymmetry in which magnetic waves (known as magnons) travelling in opposite directions are physically inequivalent, opening a route to magnetic logic operations and memory that retains data without a continuous power supply.

The effect has been understood in principle for decades, but always felt like a phenomenon that nature deliberately made inconvenient. Accessing magnetochiral anisotropy required materials that are chiral at the crystalline level – compounds like Cu2OSeO3, where the Dzyaloshinskii-Moriya interaction (DMI, a quantum mechanical force that pushes neighbouring magnetic moments to twist relative to each other) emerges only from a non-centrosymmetric crystal lattice that takes considerable effort to synthesize.

And even after synthesis, the device still needs cooling to cryogenic temperatures and application of an external magnetic field just to function. As a result, a phenomenon with genuine technological promise has spent most of its life confined to fundamental research, perpetually interesting and perpetually out of reach.

A research team headed up at École Polytechnique Fédérale de Lausanne (EPFL) has come up with a way to move this technology closer to real-world application. The idea is deceptively simple: stop asking which material can provide chirality, and start asking whether the shape of the structure itself can do the job instead. It turns out it can – as the team demonstrated, not just in a theoretical prediction, but as an actual measurement, at room temperature and with zero applied magnetic field.

Dirk Grundler, head of EPFL’s Laboratory of Nanoscale Magnetic Materials and Magnonics, and collaborators showed that a structural twist, in the form of a helical surface relief printed onto an otherwise ordinary polycrystalline nickel nanotube, is sufficient to induce chirality. The torsion and curvature of the twist generate a shape anisotropy and force the magnetic ground state into a spiralling spin texture. Its toroidal moment does exactly what the DMI does in a natural chiral crystal – it breaks the symmetry of the magnon dispersion relation, which describes how the energy of a magnetic wave depends on its direction of travel.

These twisted structures, termed artificial chiral magnets (ACMs), satisfy three conditions that no natural chiral magnet has jointly met: room temperature stability, zero field operation and realization in polycrystalline nickel – a material that is naturally achiral.

ACM outperforms a natural chiral crystal

The researchers used two-photon lithography to write the twisted polymeric scaffold and atomic layer deposition to coat it with a conformal 30-nm thick nickel shell. The handedness of the design is directly inherited by the magnetic ground state – as confirmed by X-ray magnetic circular dichroism microscopy – and can be flipped by field history, producing opposite helicity states in the same structural device on demand.

The team also performed microfocused Brillouin light scattering spectroscopy to resolve the magnon dynamics. At zero field and room temperature, the intensity non-reciprocity parameter (the difference in signal strength between waves travelling in opposite directions) reached 35.7%, switching reproducibly between two stable configurations (spin texture spiralling clockwise or anticlockwise) under field cycling without drift or degradation. At ±250 mT, the frequency non-reciprocity parameter (how much the frequency of a magnetic wave changes depending on which way it travels) peaked at 5.4×10-2, nearly three times the value reported for the bulk chiral material Cu2OSeO3 at cryogenic temperature.

Overall, the geometrically engineered nickel tube at room temperature outperformed a natural chiral crystal at low temperature. Using micromagnetic simulations and analytical modelling, the team traced the origin of this non-reciprocity to two cooperating mechanisms, both of which are tied to the geometry of the tube rather than the chemistry of the material, and both of which scale with decreasing tube radius. This implies that the numbers reported in this study are not a ceiling – they are a starting point.

A scalable blueprint for chirality-engineered magnonics

The most important factor in this result is not the nickel. While nickel was the material used, the principle does not belong exclusively to nickel. Because the chirality here is geometric – written into the shape of the structure rather than the chemistry of the lattice – it is transferable to any ferromagnet that can be deposited conformally over a three-dimensional scaffold.

Analytical calculations predict that permalloy, a nickel–iron magnetic alloy with higher saturation magnetization and exchange stiffness than nickel, should produce stronger non-reciprocity in an identical geometry. And since non-reciprocity scales with decreasing tube radius, sub-100-nm geometries accessible through next-generation two-photon lithography represent a direct route to significantly amplified effects.

Moreover, this ACM structure is multifunctional by design. Spin waves travelling through the helical magnetic structure behave differently depending on their characteristics. Some move quickly and directionally, making them suitable for carrying signals. Others are nearly stationary and strongly asymmetric – they travel in one direction and are blocked in the other, which is the defining behaviour of a diode.

The twist of the magnetic texture (clockwise or anticlockwise) can also be set by a magnetic field pulse and held indefinitely without requiring any power, functioning as a memory that stores information in the handedness of the spin arrangement rather than in a voltage or a charge. Because this directional asymmetry of magnetochiral anisotropy is a property of the geometry and not just of the spin waves, electrical current passing through the same structure is expected to experience the same effect – flowing more easily in one direction than the other.

In other words, a single nanoscale helix could simultaneously route signals, switch them, remember them and rectify them. One structure, four functions, no exotic material – the chirality was never in the crystal, it was in the geometry.

The findings are reported in Nature Nanotechnology.

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