Terrestrial solar cells rely on capturing a broad spectrum of sunlight, particularly the low-energy, long-wavelength red and infrared regions between 800 and 1150 nm. Emulating this concept underwater fails because water acts as a fierce optical filter, strongly absorbing light at wavelengths of 630 nm or more. Furthermore, descending just a few metres deeper completely attenuates longer wavelengths. This forces the aquatic environment into a twilight zone, where virtually all red light has been absorbed, leaving only a narrow, faint blue-orange glow spanning 400 to 600 nm as the sole source of illumination.

Consequently, conventional silicon, cadmium telluride or standard 1.55 eV perovskite solar cells are poorly suited for underwater operations, as their optimal absorption regions match photons that never reach them. While these constraints have long hindered the development of underwater solar harvesting, stalling the deployment of autonomous marine infrastructure like deep-sea sensors and environmental monitors, a research team in China has now charted a clearer path forward.

In a leap toward self-sustaining underwater solar harvesting, a research team led by Wen-Hua Zhang at Yunnan University has developed a functionalized solar cell for the deep sea. As detailed in Joule, the team built a wide-bandgap perovskite solar cell that thrives in dim environments by capturing the specific blue-green light that penetrates deep water. This unique design allowed the device to generate electricity underwater with a record-breaking 34.71% power conversion efficiency at a simulated depth of 10 m.

Tuning the physics of perovskites

The researchers achieved this breakthrough by engineering a mixed-anion lead halide perovskite cell with an optimized, wide optical bandgap of approximately 1.96 eV, precisely tuned to match the narrow blue-green window of deep water. While wide-bandgap perovskites are theoretically ideal for this application, they suffer from severe material vulnerabilities on land. Exposure to intense light and heat induces volatile halide-ion migration, phase separation and high concentrations of structural defects, causing rapid degradation.

This is where the unique physics of the underwater environment and intelligent molecular engineering come together. The naturally cool temperatures (typically below 25°C) and reduced light intensities beneath the waves act as an inherent shield against thermal degradation. To address the remaining internal defects and ion migration, the researchers introduced a specialized crystallization additive, polyhexamethylene guanidine hydrochloride (PHMG), into the lead halide perovskite matrix.

The addition of PHMG completely rewrites the crystallization dynamics and surface electronic properties of the perovskite film. On a molecular level, the polymer combines a water-repelling backbone with highly stable, chemically active ions (guanidinium cations). These ions act as multisite anchors that lock into empty gaps within the crystal structure, stabilizing and strengthening the entire framework. At the same time, they act like a chemical glue, binding tightly to lead and halide ions through hydrogen bonding to lock the crystal together and prevent structural decay.

This dual-action mechanism raises the activation energy barrier for ion migration from 0.07 to 0.21 eV, effectively freezing phase segregation in its tracks. Advanced testing (using ultraviolet photoelectron spectroscopy) revealed that the PHMG shifts the film’s electronic behaviour from hole-carrying (p-type) to electron-carrying (n-type) conductivity. This shift creates a favourable energy slope (band bending) at the surface, significantly accelerating electron extraction while dramatically driving down energy losses from trapped charges (known as interfacial non-radiative recombination).

From lab simulation to the open sea

These physical adjustments translated to extraordinary performance gains. Under standard terrestrial sunlight, the modified cell achieved a certified power conversion efficiency of 16.79%. But beneath the surface, it truly shone. Tested using an underwater solar simulator containing custom-engineered multilayer interference optical filters, the small-area (0.0895 cm²) cell registered an impressive 34.71% efficiency under 10 m-deep light illumination.

Scaling up the technology, the team built large-area modules with an active area of nearly 29 cm². Shielded by a robust multilayer encapsulation of polyisobutylene, cover glass and protective epoxy resin, these modules withstood extreme hydrostatic pressures and salt-water corrosion.

Deployed on a miniature robot in the open waters of the South China Sea near Weizhou Island, the modules successfully harvested solar energy across varying depths. Even at a depth of 10 m, with severely attenuated illumination, the system maintained stable electricity production, successfully generating 324 mWh of energy to charge lithium-ion batteries underwater. These batteries were later used to illuminate a custom LED panel.

“In contrast to the lab-based static underwater solar simulator, waves, turbidity and suspended organic matter in real oceans can change the light intensity and spectral composition. This leads to substantial fluctuations in output power and reduces the power‑generation stability of the cells,” Zhang tells Physics World. “Therefore, in-field experiments of the large-area solar modules, as we carried out in the South China Sea, are indispensable to assess their real-world power generation.”

The team also performed high-temperature stress testing (accelerated thermal aging tests) and molecular decay modelling (Arrhenius degradation kinetics). These tests predicted a remarkable operational lifespan in which the device retains 80% of its initial efficiency (T₈₀ lifetime) for approximately 48,094 h, translating to 5.49 years of continuous underwater operation at a standard temperature of 25 °C. Furthermore, mass spectrometry confirmed negligible lead leakage into the surrounding water, verifying the environmental safety of the design.

By mastering the unique physics of underwater light transmission and overcoming the lattice instability of wide-bandgap perovskites, the researchers have advanced a frontier for photovoltaics. This development moves solar energy beyond its traditional terrestrial borders and lays down a path toward long-lasting, self-sustained energy networks beneath the ocean surface. Future marine biology sensors, deep-sea research cameras and submerged Internet-of-Things infrastructure could one day owe their autonomy to these high-performance underwater power grids.

When asked about how the device handles biofouling over extended periods, Zhang emphasizes the need for cross-disciplinary scaling: “The current research focuses on high-efficiency and stable solar cells, as well as the integrated application of photovoltaic energy storage systems. Indeed, biofouling is a critical challenge for the long-term operation of underwater photovoltaics. However, this issue involves multidisciplinary efforts and requires collaborative research from more scientists.”

The post Polymer-tuned perovskite creates high-efficiency underwater solar cells appeared first on Physics World.

The transplanted cells formed circuits, reached the spinal cord and responded to injury.

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Nikon’s 2026 Small World in Motion competition showcased the best microscopic footage of the year, usually invisible to the human eye.

Scientists have uncovered two surprising forces that help guide how the human brain forms before birth. Before birth, the human brain is shaped in large part by an unusual class of stem cells known as radial glia. These cells help determine which brain cells are produced, when they appear, and how the cerebral cortex, the [...]

The evolutionary part of this paper relies on wishful thinking. What “could” or “might” happen occurs only in their evolutionary imaginations.

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The proposal ceases to be an inference from observations and known physics and becomes an appeal to the absurd.

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In one episode of the Hanna-Barbera cartoon Birdman, the eponymous hero struggles to fight the evil Dr. Shark aboard a submarine without solar energy to recharge his powers. So Birdman would surely appreciate the new perovskite solar cells developed by a team led by Simin Ma at Yunnan University, since they are designed to work underwater.

Solar cells made from perovskites rather than silicon are always a tale of trade-offs. They can be made cheaply, they can take interesting forms (like thin, flexible, transparent films), and they can convert substantially more of the incoming solar energy into electricity. The difficulty is that they tend to degrade quite quickly.

Tuned for the deep

Moisture is particularly destructive to perovskites, making them a seemingly odd choice for an underwater solar panel. But these materials have another critical superpower: They can be tuned to work with different wavelengths of light. Water quickly blocks the wavelengths of light that silicon solar panels absorb, but a carefully designed perovskite cell could still make electricity in the deep blue sea. And actually, the lower light levels and cooler temperatures should help it live longer.

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© Richard A. Brooks

UCLA scientists engineered ready-made T cells from cord blood stem cells that can hunt solid tumors even when cancer cells hide their main target. T cell receptor therapy, commonly called TCR therapy, is a form of cancer treatment that genetically modifies immune cells known as T cells so they can recognize and attack cancer more [...]

Oracle’s proposed investment in 2 gigawatts of renewable energy projects for New Mexico comes as local opposition could delay development of the Project Jupiter data center that Oracle is building for OpenAI.

The two tech companies are developing the $165 billion Project Jupiter data center in Santa Teresa, New Mexico, as part of the broader Stargate AI infrastructure project announced by President Donald Trump in 2025. But Project Jupiter faces local protests and court battles over concerns about its environmental impacts—and the latest Oracle announcement on September 8 seeking proposals for renewable energy projects does not change the fact that the data center will be powered by fuel cells that consume natural gas.

“Like all matching programs, this would be synthetic in the sense that 2 GW of renewables wouldn't directly power the data center,” wrote Michael Thomas, CEO of the Cleanview data platform that tracks renewable energy and data center projects, in a LinkedIn post.

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© STACK Infrastructure

For more than four decades, pathologists have glimpsed something unsettling under the microscope in the earliest stages of certain cancers: cells with nuclei far larger than they should be, swollen and distorted, lurking in tissue that otherwise appears on the verge of catastrophe. These so-called giant-nucleus cells, or karyomegalic cells, were first spotted in the 1980s in animal experiments involving iron-induced oxidative stress, yet their biological identity and their role in the genesis of cancer remained stubbornly obscure. Now, a team of researchers in Japan has provided the most detailed portrait of these cells to date, and their findings suggest that the enormous nuclei may be far more than a curiosity—they could be the founding population of early cancer, visible before any tumor exists, and potentially useful as a predictor of patient outcomes.

The study, led by Shinya Toyokuni, professor emeritus at Nagoya University Graduate School of Medicine, together with assistant professor Yingyi Kong and colleagues, was published in Redox Biology. The work addresses a deceptively simple question: when iron overload kills most cells in a tissue through oxidative damage, who survives, and what do the survivors become? Iron is an essential micronutrient, but in excess it is a potent carcinogen. Its chemistry is both the reason we need it and the reason it can harm us. Iron catalyzes the formation of hydroxyl radicals from hydrogen peroxide through the Fenton reaction, and these radicals shred DNA, oxidize lipids, and damage proteins. When the damage is severe enough, a form of programmed cell death called ferroptosis is triggered—an iron-dependent demise characterized by lipid peroxidation cascades that rupture the cell membrane. Ferroptosis has become one of the hottest topics in cancer biology precisely because it links iron metabolism, oxidative stress, and cell fate in a single mechanism.

Toyokuni’s team reasoned that if ferroptosis sweeps through iron-damaged tissue, the cells that escape it must be exceptional in some way, and those exceptions might be the seed of malignancy. To find out, they turned to a well-established animal model in which ferric nitrilotriacetate, a carcinogenic iron compound, is injected into rats, delivering a bolus of iron to the kidneys. The compound accumulates in the proximal tubules, where it catalyzes oxidative damage and, over months, produces renal cell carcinoma. In the experiments, the researchers collected kidney tissue before the injection and again one and three weeks afterward. Crucially, they also included a second experimental group: rats carrying a single mutated copy of the BRCA1 gene, the same gene that, when mutated in humans, dramatically raises the risk of breast and ovarian cancers and is associated with renal carcinoma in certain contexts.

The methodological heart of the study lies in its marriage of two technologies. The first is spatial transcriptomics, a technique that maps gene activity across individual cells within a tissue section while preserving the tissue’s original architecture—so researchers can see not only which genes are active but where in the tissue those transcriptional programs are operating. The second is computational nuclear morphometry, which quantifies the size, shape, and density of cell nuclei in the same samples. By overlaying the two datasets, the team could link the physical appearance of each cell—above all, the size of its nucleus—to its underlying transcriptional state. This integration is important because morphological atypia has long been the currency of diagnostic pathology, but connecting that atypia to molecular signatures at single-cell resolution is a recent capability.

What emerged within a week of iron administration was striking. Giant-nucleus cells appeared in the damaged kidneys, and these cells were not simply wounded cells awaiting death. They showed elevated expression of potent oncogenes, including Myc and Met, and they had acquired resistance to ferroptosis—the very cell death pathway that was eliminating their neighbors. In other words, the extreme oxidative environment had functioned as a brutal selective pressure, and the cells best adapted to survive it had activated a program that resembles, in miniature, the hallmark machinery of cancer. The enrichment of Myc, a transcription factor that drives cell growth and proliferation, and Met, a receptor tyrosine kinase involved in invasive growth, paints a picture of cells that are not merely enduring damage but reorganizing themselves around it.

The BRCA1 connection proved equally consequential. BRCA1 is best known as a guardian of the genome, a scaffold for the homologous recombination machinery that repairs double-strand DNA breaks. In the BRCA1-mutant rats, giant-nucleus cells emerged with distinctly different biological profiles from those in wild-type animals. The interpretation the researchers offer is that BRCA1 deficiency cripples DNA repair, so more of the damaged cells that would otherwise die or be repaired instead survive in their injured, genome-compromised state—becoming precancerous giant-nucleus cells. Electron microscopy and cellular respiration measurements reinforced this idea at the subcellular level: cells from BRCA1-mutant rats showed mitochondrial remodeling, with impaired iron handling and compromised respiratory function. Mitochondria, long appreciated as power plants, are also central regulators of ferroptosis and iron metabolism, and their disarray in the mutant animals may be both a consequence of BRCA1 loss and a driver of the abnormal iron biology that feeds karyomegaly.

Using their combined gene-expression and nuclear-shape data, the researchers went further and classified the giant-nucleus cells into six distinct types. One type possessed extremely large nuclei and gene signatures of stress-induced growth arrest—cells that appear to have locked themselves into a senescent-like state, consistent with profiles reported in earlier studies. Another type, found more frequently in BRCA1-mutant kidneys, showed heightened activity of cancer-related genes alongside elongated nuclei, a combination the authors interpret as a potential precancerous state. The taxonomy matters because it reframes giant-nucleus cells from a single enigmatic category into a spectrum, some members of which may be harmless or even protective while others carry genuine malignant potential.

One of the most provocative findings concerns the cells surrounding the giants. Even morphologically normal cells near giant-nucleus cells exhibited gene expression changes that appear to promote survival, suggesting that the karyomegalic cells remodel their local microenvironment in ways that extend beyond their own borders. In BRCA1-mutant kidneys, the team also documented a substantial increase in stromal cells—non-cancerous supportive cells including immune and connective tissue elements—around the damaged regions. The local tissue environment, the tumor niche in the language of modern oncology, was being reshaped long before any tumor could be called a tumor. This raises the possibility that a single conspicuous cell, easily identified by its nucleus under a conventional microscope, could serve as a sentinel for a whole neighborhood of incipient malignancy.

The leap from rat kidneys to human medicine came through two complementary analyses. First, the researchers mined TCGA-KIRC, a large public database of kidney cancer patients, asking whether tumors carrying gene-expression patterns resembling the cancer-prone giant-nucleus cells were associated with different clinical trajectories. They were: patients whose tumors shared the gene patterns of the cancer-prone giant-nucleus cells had shorter survival times, while those with patterns resembling the healthier giant-nucleus cell types had better outcomes. Not all giant-nucleus cells, in other words, are created equal, and the transcriptional fingerprints defined in the rat model appear to carry prognostic weight in human disease. Second, in a small pilot study, the team examined breast tissue from seven individuals with inherited BRCA1 mutations and fifteen without, observing abnormal nuclear features similar to those in the animal model in the mutation carriers. While the sample size is modest, the parallel hints that karyomegaly may be a cross-tissue marker of BRCA1-linked precancerous change.

The broader implications run in two directions. Clinically, the promise is that giant-nucleus cells, being easy to spot under the microscope, could function as early indicators of cancer—visible warnings in tissue that would otherwise be classified as merely damaged or inflamed. The TCGA survival data suggest that their gene-expression signatures might even stratify patients by risk once a tumor has formed. Scientifically, the study offers a concrete mechanism connecting an environmental exposome factor—iron-catalyzed oxidative stress—to a defined, transcriptionally characterized precancerous population, with ferroptosis resistance as the pivot. It also implies testable therapeutic hypotheses: if blocking mitochondrial remodeling or reversing ferroptosis resistance could prevent the persistence of the precancerous cells, early intervention might stop cancer before it starts. Toyokuni and his colleagues are careful to note that long-term studies will be needed to determine how giant-nucleus cells actually progress into tumor cells, whether such interventions can work, and whether nuclear shape combined with gene patterns can be validated as a diagnostic in larger patient cohorts. But the central message is already legible: some of the earliest chapters of cancer may be written in cells that have grown too large to be ignored.

Researchers at the Helmholtz-Zentrum Berlin (HZB) in Germany have overcome a long-standing barrier in next-generation photovoltaics by developing a new type of all-perovskite triple-junction solar cell. Perovskites are a class of synthetic materials with a unique crystal structure that excel at absorbing light, while a triple-junction design stacks three distinct perovskite sub-cells together, each tuned to capture a different part of the solar spectrum to maximize energy harvesting. With this combination, the device achieved a power conversion efficiency of 27.3%.

Stacking three such individual sub-cells allows multi-junction devices to bypass the theoretical efficiency ceiling of traditional single-junction solar cells. However, their real-world implementation has been severely constrained by optical and electrical losses at the buried interfaces of their narrow-band-gap sub-cells. By introducing a novel graphene oxide and self-assembled monolayer (SAM) bilayer strategy, the HZB team has effectively suppressed these losses, unlocking both high efficiency and unprecedented operational stability.

The challenge of buried interfaces

The main bottleneck in multi-junction all-perovskite architectures centres on the narrow-band-gap tin-lead bottom sub-cell, which captures near-infrared light. For years, the field has relied on an organic polymer called PEDOT:PSS as the hole-transport layer to extract positive charges from this sub-cell. However, PEDOT:PSS suffers from a high degree of parasitic light absorption, robbing the underlying bottom cell of valuable incoming photons. Furthermore, its highly acidic and hygroscopic nature chemically degrades the sensitive perovskite material, creating a critical compromise between efficiency and device lifespan.

This results in a severe material trade-off, whereby a layer intended to extract electric charge ends up blocking the very light needed to generate that charge, all while slowly destroying the underlying solar cell structure.

To move away from PEDOT:PSS, researchers have frequently looked to SAMs, molecularly engineered alternatives that perform exceptionally well in pure lead-based perovskites. Yet, when deposited directly onto tin-lead perovskite layers, SAMs present an unexpected physical anomaly, triggering severe internal electrical field screening and inducing uneven grain growth at the buried interface. Using fast-hysteresis measurements and bias-assisted charge extraction measurements, the HZB team discovered that standard carbazole-based SAMs lead to massive ion accumulation, which severely hinders the cell’s ability to separate and extract photogenerated charge carriers.

Unlocking charge flow with a molecular bilayer

Led by Steve Albrecht, the HZB team designed a synergistic bilayer to circumvent this destructive ion accumulation and field-screening mechanism. They deposited an ultrathin, uniform layer of hydrophilic graphene oxide directly onto the transparent indium tin oxide conductive base, before introducing a specialized SAM molecule, MeO-2PACz. The phosphonic acid head groups of the SAM anchor strongly onto the oxygen-containing functional groups of the graphene oxide via hydrogen and covalent bonding.

This chemical arrangement prompts a favourable molecular reorientation that deepens the layer’s electronic work function, markedly enhancing its electrical conductivity. Additionally, the graphene oxide provides a smooth, hydrophilic foundation that accelerates crystal nucleation, generating a uniform, high-quality perovskite film completely free of the microscopic empty spaces (nanovoids) that plague SAM-only devices in this study.

When integrated into single-junction tin-lead solar cells, the new bilayer achieved a standalone power conversion efficiency of 22.1%, heavily outpacing the 12.0% efficiency of SAM-only equivalents. Using optoelectronic characterization, the team confirmed that this massive improvement was driven almost entirely by the mitigation of internal electronic and ionic extraction losses.

Record stability and the path to 30%

The researchers demonstrated the true potential of this technique when they integrated the bilayer into a monolithic triple-junction stack featuring sub-cells with band gaps of 2.00, 1.60 and 1.25 eV. By replacing the conventional gold and PEDOT:PSS interconnecting layers with an optimized indium tin oxide and graphene oxide/SAM bilayer configuration, they minimized parasitic light absorption in the near-infrared spectrum. This structural optimization raised the short-circuit current density of the narrow-band-gap bottom cell to 10.3 mA/cm², driving the overall triple-junction efficiency to 27.3%.

Beyond the efficiency milestone, the chemically benign and robust nature of the graphene oxide/SAM interface yielded exceptional longevity. While traditional PEDOT:PSS-based cells degrade rapidly due to chemical interactions, the encapsulated bilayer devices successfully retained 90% of their initial performance after 770 h of continuous operational tracking under 1-sun illumination at room temperature. This sets a new stability record for triple-junction all-perovskite configurations.

The team notes that the current triple-junction performance is still bound by slight current mismatches and series-resistance transport losses across the interconnecting sub-cell junctions. By further optimizing the quality of the wider-band-gap perovskite layers and fine-tuning the band alignments of the intermediate contacts, the researchers project that the efficiency of this multi-junction solar architecture can comfortably clear the 30% barrier in the near future.

The solar cell design is detailed in Joule.

The post Bilayer approach ramps performance of all-perovskite triple-junction solar cells appeared first on Physics World.

A compound produced in the body after eating pomegranates improved heart function by up to 80% in experimental models of a type of heart failure with limited treatment options. For people with heart failure with preserved ejection fraction, the heart can still pump blood but struggles to relax and refill properly between beats. In experimental [...]

That’s now just 1 billion years for all the apparatus to hit on the lucky combination randomly, unless we start with design principles.

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How immune cells develop and retain memory may work differently than medical scientists previously believed, according to an international team of researchers.

The new work shows that T cells—white blood cells essential to immune function—can respond to the physical properties of their surroundings through a kind of cellular sense of touch.

The researchers published the work in Nature Immunology, altering our understanding of how immune cells develop, and potentially improving scientists’ understanding of how the immune system adapts to the varied physical environments found throughout the human body.

T Cells Explained

The various specialized types of T cells serve crucial roles in the immune system. Some directly fight infections, while others help coordinate the immune response. Scientists have long believed that biochemical signals help shape the memory T cells that persist in tissues following an infection, preserving the body’s ability to respond to previously encountered threats. How these cells migrate and eventually settle into strategic positions throughout the body is a key part of the immune response.

As T cells travel through the body, they continually monitor for signs of pathogens. When a threat is detected, T cells can enter affected tissues and help clear the infection. Once the invaders have been repelled, some T cells remain in the tissue to guard against reinfection. These tissue-resident memory T cells help defend against previously encountered threats but can also play roles in autoimmune disorders and the rejection of transplanted tissue.

Over their lifetimes, T cells can develop into increasingly specialized forms. Naive T cells have not yet encountered the specific antigen they are capable of recognizing. Following activation, they can differentiate into effector T cells that help target a particular threat, with some eventually developing into long-lived memory cells.

Tissues in the Body

Tissues in our bodies vary widely in stiffness, ranging from the very soft adipose tissue that makes up our body fat to the much stiffer skeletal muscle tissue. These differences raise an interesting question: how do T cells remain strong enough to survive the pressures of stiffer tissues while staying soft enough to change shape as they slide through obstacles in our bodies?

For their laboratory experiments, the researchers reproduced typical tissue stiffnesses using specially engineered collagen gels. They then placed human and mouse immune cells into the gels and discovered that T cells were more likely to develop characteristics associated with tissue-resident memory cells in stiffer environments.

Previously, scientists believed biochemical signals were the primary driver of tissue-resident memory T cell development. In their new research, the team found that these cells use touch to sense the mechanical pressure of their surroundings, dictated by tissue stiffness, and adjust their morphology to compensate.

“This is an exciting fundamental finding that challenges the way we think about immune cells,” said lead author Judith Mandl, a professor in McGill University’s Department of Physiology. “It suggests T cells can ‘feel’ their surroundings and adapt to them, making the physical environment an active force in shaping their behaviour.”

Correcting T Cells

While T cells normally function to protect us from illness, they can occasionally create problems of their own. Patients with autoimmune diseases and allergies may see these immune cells begin attacking healthy tissue. Additionally, organ transplant patients typically require immunosuppressant drugs to stop their T cells from rejecting the new organ.

“Tumours are often dense and physically difficult for immune cells to penetrate. Understanding how T cells adapt to these environments could help researchers design cancer immunotherapies that are better able to reach and attack tumours,” said Mandl.

This new research is an important first step in a new understanding of how immune cells differentiate, which could lead to a new foundational understanding of how to correct undesired immune responses.

The paper, “Mechanosensing by T Cells Promotes a Tissue-Resident Memory Transcriptional Program,” appeared in Nature Immunology on July 3, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org.

A protein called TRAILshort may act as a central immune brake that limits T-cell responses and CAR-T therapy. Cancer cells can weaken the immune system by producing a protein that prevents its most important defenders from attacking. Mayo Clinic researchers have identified how this protein works, revealing a possible target for treatments designed to improve [...]

Fuchs endothelial corneal dystrophy, a progressive disorder that can gradually cloud the cornea and impair vision, may be driven by a cellular process more complex than simple cell loss. A new study published in Cell Death Discovery reports that ultraviolet-A light can induce chronic hyperploidization in corneal endothelial cells, triggering changes associated with fibrosis. The findings connect long-term genome abnormalities in post-mitotic cells to the structural deterioration observed in this increasingly recognized eye disease.

The cornea depends on a thin inner layer of endothelial cells to maintain its transparency. These cells regulate the movement of fluid between the cornea and the anterior chamber of the eye, preventing the tissue from becoming waterlogged. Unlike many cell types, human corneal endothelial cells have limited ability to divide and replenish themselves. When they are damaged or lost, neighboring cells may enlarge and stretch to cover the affected area, but this compensation has limits. In Fuchs endothelial corneal dystrophy, the endothelial layer progressively becomes dysfunctional, allowing fluid accumulation and producing corneal swelling, haze and visual distortion.

The study focuses on hyperploidization, a condition in which cells acquire extra sets or copies of chromosomes. In a healthy cell cycle, DNA is replicated and then evenly distributed when a cell divides. Post-mitotic cells, however, are not expected to continue cycling through repeated rounds of DNA replication. If DNA replication occurs without successful cell division, the result can be a cell with an enlarged genome and multiple chromosome sets. This state, known as polyploidy or hyperploidization depending on its extent and context, can alter cell size, metabolism, gene activity and responses to stress.

The researchers investigated how ultraviolet-A, or UVA, light affects cells associated with Fuchs endothelial corneal dystrophy. UVA has a longer wavelength than ultraviolet-B and can penetrate biological tissues more deeply. Although the eye possesses protective mechanisms, persistent or excessive exposure to light-generated stress can damage cellular components, including DNA, proteins and mitochondria. The study indicates that UVA exposure does not merely cause an acute injury that cells either repair or fail to survive. Instead, it can establish a chronic hyperploid state in cells that no longer divide normally.

That distinction is important because a cell can remain alive while becoming increasingly dysfunctional. Hyperploid cells may continue to produce proteins, communicate with neighboring cells and modify their surrounding environment, even as their enlarged genomes disrupt normal regulation. In the corneal endothelium, such persistent abnormalities could interfere with the machinery responsible for maintaining fluid balance and tissue transparency. The research links this long-lasting cellular state to the activation of fibrotic processes, suggesting that damaged endothelial cells may help remodel the cornea rather than simply disappearing.

Fibrosis is the formation or accumulation of excessive connective-tissue components, particularly extracellular matrix proteins such as collagens. During wound healing, matrix production can provide temporary structural support. When the response persists, however, the tissue can stiffen, become disorganized and lose its normal optical properties. In the context of Fuchs endothelial corneal dystrophy, fibrosis may contribute to the loss of corneal clarity and the progression of visual impairment. The study’s central message is that chronic hyperploidization may act as an upstream signal that pushes post-mitotic cells toward this pathological remodeling.

The findings also help explain why a disease affecting a specialized, non-dividing cell population can progress over time. A conventional view of cellular damage often emphasizes apoptosis, necrosis or the gradual depletion of functional cells. The new work highlights another possibility: injured cells may survive in a permanently altered condition and actively influence disease progression. By retaining metabolic activity while carrying abnormal quantities of DNA, these cells could produce signals that encourage inflammation, matrix deposition or changes in the behavior of nearby cells.

The UVA connection raises questions about how environmental stress interacts with inherited susceptibility. Fuchs endothelial corneal dystrophy has genetic and age-related components, and the disease does not arise from a single universal cause. The study does not establish that UVA exposure alone causes the disorder, but it provides a mechanism through which light-associated stress could worsen cellular instability in vulnerable corneal tissue. This may help researchers examine whether cumulative exposure, cellular antioxidant capacity and pre-existing genetic changes combine to determine how rapidly the disease advances.

From a treatment perspective, the work points toward targets beyond replacing lost endothelial cells. Future strategies might seek to prevent abnormal DNA replication, stabilize genome integrity, suppress the fibrotic signals released by hyperploid cells or protect the corneal endothelium from chronic light-induced stress. Such approaches would require careful testing, because polyploidy can serve useful roles in some normal tissues, and broadly blocking cell-cycle or repair pathways could produce harmful effects. The challenge will be to distinguish pathological hyperploidization from adaptive genome changes that help cells survive.

The study ultimately presents Fuchs endothelial corneal dystrophy as a disease of cellular identity as well as cellular survival. UVA-induced chronic hyperploidization appears to place post-mitotic corneal endothelial cells in a persistent state of genomic imbalance, where they can contribute to fibrosis and tissue failure. By connecting light stress, abnormal DNA content and corneal scarring, the research offers a new framework for understanding why the disease can continue even after the initial injury has passed—and provides a potential roadmap for therapies designed to interrupt the process before vision is permanently compromised.

Subject of Research: Ultraviolet-A light-induced chronic hyperploidization and fibrosis in post-mitotic corneal endothelial cells affected by Fuchs endothelial corneal dystrophy

Article Title: Ultraviolet-A light-induced chronic hyperploidization causes fibrosis in post-mitotic cells affected by Fuchs endothelial corneal dystrophy

Article References: Adhikari, Y., Parekh, M., Deshpande, N. et al. Ultraviolet-A light-induced chronic hyperploidization causes fibrosis in post-mitotic cells affected by Fuchs endothelial corneal dystrophy. Cell Death Discov. (2026). https://doi.org/10.1038/s41420-026-03292-8

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41420-026-03292-8

Keywords: Fuchs endothelial corneal dystrophy, ultraviolet-A, UVA, hyperploidization, polyploidy, corneal endothelial cells, fibrosis, post-mitotic cells, genome instability, corneal disease

T cells may use a previously unknown CD64-dependent pathway to attack acute myeloid leukemia. T cells are generally thought to identify cancer through a well-established molecular recognition system. Yet when researchers removed a key part of that system from acute myeloid leukemia (AML) cells, the immune cells continued killing them. The unexpected result led scientists [...]

Macrobiological features have been cited as irreducibly complex, including animal joints and the trap mechanisms of carnivorous plants, even the cell itself.

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A protein and signaling pathway may help overcome the developmental block that keeps some leukemia cells immature. Inside the bone marrow, immature blood cells normally pass through a tightly controlled sequence of development before taking on specialized roles. In aggressive forms of leukemia, some of these precursor cells become trapped partway through that process. Instead [...]

The Varta crisis has entered another severe phase after the German battery manufacturer lost the customer responsible for nearly all production at its specialized factory in Nördlingen.

Varta has not publicly identified that customer, but reports from German media and industry sources point to Apple. The iPhone maker is reportedly moving battery orders for a future AirPods generation to a lower-cost supplier in China.

The decision will lead Varta to stop producing rechargeable button cells in Nördlingen during fall 2026. Approximately 350 jobs will be eliminated across the factory and the company headquarters in nearby Ellwangen.

Describing the development as a complete corporate collapse would go too far. Varta continues operating other battery businesses and recently completed an extensive financial restructuring backed by Porsche. The loss of Apple, however, has destroyed the economic foundation of a production site created around one highly influential customer.

Varta Crisis Exposes Dependence on Apple

The Varta crisis illustrates how a large technology customer can transform a supplier and then leave it with capacity that cannot easily be reassigned.

Varta became an important producer of CoinPower lithium-ion cells, small rechargeable batteries designed for wireless earbuds and other compact devices. Teardowns of AirPods Pro models identified Varta cells inside the earbuds, although Apple does not publicly discuss most component suppliers by product.

Demand from premium wireless headphones helped Varta expand rapidly. In 2020, its Microbatteries and Solutions division generated approximately €508 million in revenue, representing growth of 49% from the previous year.

The company invested heavily in production as wireless earbuds became a mass-market category. Apple demand provided the volume needed to justify specialized lines, equipment and hiring in Germany.

That dependence became dangerous when AirPods production weakened and Apple began adding other battery suppliers. A factory developed for unusually large orders could not operate efficiently once those orders declined.

The customer now leaving Nördlingen had previously accounted for nearly the entire capacity of the site. Varta says it has gained other customers, but their combined demand is not sufficient to keep the specialized factory running.

The plant is therefore closing not because rechargeable button cells have disappeared, but because replacing one customer of Apple scale requires far more than several smaller contracts.

Price Reportedly Decided the AirPods Order

German reports indicate that price was the decisive factor behind the supplier change.

Varta battery quality was reportedly equal to or better than the competing product. The German manufacturer could not, however, match the cost offered for the next generation of cells from China.

Battery production in Germany faces higher labor, energy and operating expenses than many Asian manufacturing centers. Chinese suppliers also benefit from extensive domestic electronics supply chains, access to materials and production volumes spread across numerous customers.

Apple has enormous leverage when negotiating component contracts. AirPods ship in sufficient quantities for a small difference in the cost of each battery to produce substantial savings across an entire product cycle.

The company regularly qualifies multiple suppliers for components when technical requirements and available capacity permit. Competition can reduce prices, protect production against interruptions and prevent one manufacturer from gaining excessive influence over the supply chain.

For Varta, that process brought the opposite effect. The supplier expanded to serve Apple and then faced declining utilization as the customer divided orders among additional manufacturers.

The latest move appears more final. Varta expects the contract to expire at the end of October, removing the volume that kept Nördlingen economically viable.

Apple Supplier Strategy Is Not Simply About China

The reported decision does not mean Apple is moving its complete production network toward China.

Apple has spent several years expanding device assembly and component production in India, Vietnam and other countries. AirPods manufacturing has grown in India, while Macs, iPads and wearables are assembled across a wider group of Asian locations.

The Varta case concerns a particular component for which a Chinese supplier reportedly offered a more competitive price. It shows that diversification away from one country can coexist with cost-driven sourcing from that same country.

Apple may reduce its dependence on Chinese final assembly while continuing to purchase Chinese batteries, displays, enclosures or electronic components when suppliers provide the required scale and pricing.

That balance creates a difficult environment for European manufacturers. Political interest in domestic technology production does not guarantee that major customers will accept higher component prices.

Premium engineering can protect a contract when it produces a measurable advantage in battery capacity, safety, dimensions or lifespan. Once competing suppliers reach comparable performance, procurement decisions become increasingly sensitive to cost.

The Varta crisis suggests that manufacturing location and supplier history carried less weight than the economics of the next AirPods battery.

Varta Was Already Fighting Financial Failure

Apple did not create every problem affecting Varta.

The company entered the current dispute after years of debt, costly investments, volatile customer orders, supply-chain problems and weaker demand in parts of its energy-storage business. A cyberattack in early 2024 also disrupted production and delayed financial reporting.

Varta warned that its earlier restructuring plan might fail after Apple reduced AirPods production. By mid-2024, the company had reached a point where it could no longer service its debt without another intervention.

A pre-insolvency restructuring reduced financial liabilities from approximately €485 million to €200 million. Porsche and majority shareholder Michael Tojner agreed to provide new capital, while creditors supplied additional financing.

Existing shareholders lost their investment as Varta was removed from the stock market. The process preserved the operating company but demonstrated how little financial room remained for another major disruption.

Varta reported a loss of €64.5 million for 2024. Although that was an improvement from the previous year, the business remained dependent on successful restructuring and stronger performance from its surviving divisions.

The Apple contract loss therefore did not independently bring down a healthy battery group. It struck a manufacturer that had already narrowly avoided insolvency.

Porsche Cannot Protect Every Varta Business

Porsche participation gives Varta a future in automotive batteries, but it does not rescue the Nördlingen button-cell operation.

The automaker invested in the restructuring and took control of the V4Drive business, which develops high-performance cylindrical lithium-ion cells for hybrid and performance vehicles. Porsche gains greater access to battery technology while helping retain part of that expertise in Germany.

Varta also continues producing household batteries and energy-storage systems. Those businesses serve different customers and do not depend on the machinery used for tiny CoinPower cells.

Employees affected by the Nördlingen closure may be offered positions at other locations, although Varta has not indicated how many can realistically be transferred. The company and its works council are negotiating measures for the workers whose roles will disappear.

The shutdown leaves a modern production unit without enough demand only a few years after wireless earbuds were presented as one of Varta most promising growth markets.

Its remaining automotive operation now has the security of a strategic customer with a direct ownership interest. The microbattery division learned the cost of building a factory around a customer that never made the same commitment.

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