It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Monday, August 18, 2025
Novel radio-photovoltaic cells: A breakthrough in nuclear battery technology
Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, CAS
Figure | Device structure and working principle WLC-based RPVC. a, Device materials and configuration of the RPVC. b, Schematic diagram of the assembling structure and working principle of the RPVC.
The advancement of technology has spurred human exploration into extreme environments. However, conventional power systems face significant challenges in such scenarios, particularly in terms of energy density, durability, and maintenance. Traditional batteries, hampered by their structural design and energy sources, are unable to meet the demands of long - term, autonomous operation in harsh conditions.
A collaborative team, led by Prof. Haisheng San from Xiamen University in China, Prof. Xin Li from the China Institute of Atomic Energy in China, and their colleagues, has made a remarkable breakthrough in this field. In a new paper published in Light: Science & Applications, they presented a novel 90Sr radio-photovoltaic cells (RPVC) based on a waveguide light concentration (WLC) structure. This innovative design integrates multilayer-stacked GAGG:Ce scintillation waveguides with 90Sr radioisotopes.
Electron beam irradiation and tests using an 85Kr radioisotope source revealed that the edge surfaces of the GAGG:Ce scintillation waveguides exhibited highly efficient radioluminescence emission. A prototype of the RPVC achieved a maximum output power of 48.9 μW and an unprecedented energy conversion efficiency of 2.96%. Moreover, a multi-module integrated RPVC prototype demonstrated a maximum output power of 3.17 mW, a short-circuit current of 2.23 mA, and an open - circuit voltage of 2.14 V. Remarkably, after undergoing a 50-year equivalent electron beam irradiation, the device showed only a 13.8% optical performance degradation, confirming its exceptional radiation hardness. These findings indicate that WLC-based RPVCs can achieve both high power output and outstanding long-term stability, representing a substantial advancement in facilitating nuclear battery applications.
The scientists summarized the advantages of their nuclear battery, stating, "We designed and fabricated an RPVC that achieves a balance between efficiency and stability. The WLC structure realizes a 3-fold improvement in energy conversion efficiency compared with conventional RPVC structures. The irradiation equivalent to 50 years of service confirms that WLC-based RPVCs have great long-term service stability." They also added, "Although large-scale production of RPVCs is still limited by challenges such as mass production and cost reduction of 90Sr radioisotopes, the current research results mark a substantial step forward in promoting nuclear battery applications."
High-efficiency 90Sr radio-photovoltaic cells based on waveguide light concentration structure
Figure | Enhanced emission verification and prototype performance of WLC-based RPVC. a, Experimental platform andb, test results of scintillation waveguide edge enhancement emission.c, Radioluminescence spectrum of GAGG:Ce and quantum efficiency curve of photovoltaic cell. Electrical output for RPVC prototype withd, single module ande, multi-modules.
Credit
Tongxin Jiang et al.
Global telecommunications at risk: New paper urges urgent rethink of submarine cable dependence
A newly published paper by Dr. Asaf Tzachor, Dean of Reichman University's School of Sustainability, warns that the backbone of our global internet infrastructure — submarine communication cables — is dangerously vulnerable to both natural disasters and deliberate sabotage, posing systemic risks to international communication, commerce, and security.
"The world's overreliance on a uniform submarine cable network is a textbook case of a progress trap", says Dr. Tzachor. "While cables have enabled a connected planet, they also represent a fragile chokepoint in global communications".
Published in Nature Electronics, the study details the growing vulnerability of submarine cables — which transmit over 95% of the world’s international data — to both natural and man-made hazards.
In 2022, the eruption of the Hunga Tonga-Hunga Ha'apai volcano unleashed a tsunami and underwater shockwaves that snapped the fibre-optic lifeline connecting Tonga to Fiji, plunging the island nation into digital isolation for weeks. This was not an isolated event. In 2011, Japan’s devastating 9.0 magnitude Tōhoku earthquake disrupted trans-Pacific telecommunications, while a 2006 earthquake off Taiwan’s southwest coast triggered submarine landslides in the Luzon Strait that severed critical cables linking Hong Kong, China, the Philippines, and Japan. The fallout was global — Hong Kong’s internet was nearly paralyzed, and financial markets around the world felt the ripple effects.
More recently, in just the past 18 months, a spate of incidents has exposed the system’s fragility. Submarine cables in the Red Sea, Baltic Sea, and Pacific have been damaged — some likely the result of deliberate sabotage — disrupting data flows across continents and underscoring the risks of relying on a single, vulnerable communications backbone.
Accidental damage from ship anchors and deep-sea trawlers causes frequent disruptions, while the growing trend of targeted cable sabotage by state and non-state actors raises the specter of intentional, high-impact blackouts.
If left unaddressed, these compounding vulnerabilities could cascade into large-scale communications failures with serious consequences.
From Ocean Floor to Stratosphere and Space: A New Vision
Dr. Tzachor lays out an ambitious yet scientifically grounded roadmap for diversifying global communications infrastructure beyond the ocean floor. He envisions three alternative systems that, while at varying stages of maturity, could together reduce our overreliance on vulnerable submarine cables.
The first is satellite-based laser communication networks. Already in operation through NASA and commercial ventures like Starlink, these low-Earth orbit constellations can deliver fibre-like data speeds without the seismic or geopolitical risks that threaten undersea systems. While atmospheric interference remains a technical hurdle, advances in beam steering, adaptive optics, and high-throughput inter-satellite links suggest enormous potential.
The second solution takes to the skies. High-altitude platform systems, or HAPS, involve solar-powered drones and airships stationed in the stratosphere. Acting as floating, low-latency data relays, they've proven useful in emergencies and remote regions. Though still early in development, prototypes have shown that these platforms could one day provide agile and resilient internet infrastructure — particularly for areas underserved by current cable networks.
The third approach dives below the surface. Autonomous underwater optical wireless networks imagine swarms of robotic vehicles equipped with blue-green lasers, forming a dynamic mesh of short-range optical links beneath the sea. These systems could offer critical redundancy near existing cables, and are especially promising for military, deep-sea energy, and environmental monitoring applications.
But technology alone won't secure the future of global communications. The paper calls for coordinated public–private action on a scale not seen since the rise of the semiconductor industry. Governments must step up with targeted funding, policy reform, and international agreements. That includes incentivizing research into alternative communications, setting clear standards for space-debris mitigation and orbital traffic management, and aligning frequency, airspace, and oceanic regulations across borders.
Only by broadening our thinking, and our investments, can we build a communications infrastructure resilient enough for the 21st century.
“Cable redundancy isn’t enough. We need genuine diversification of the global digital infrastructure if we're to withstand 21st-century threats — from geohazards to geopolitical conflict", says Tzachor.
One of the biggest challenges facing forests today is climate change adaptation and mitigation. However, Mediterranean trees are rarely included in forest conservation and sustainable management policies.
Given the lack of knowledge on trees from the Mediterranean region, a group of 30 researchers based in North Africa, the Middle East and southern Europe gathered and analysed a large data set on the presence or absence of trees across the entire geographical zone under Mediterranean climate in North Africa, Western Asia and Europe. The group was coordinated by INRAE and the European Forest Institute (EFI) and involved Aix-Marseille Université, the University of Montpellier, the French National Forest Office (ONF) and the French National Museum of Natural History (MNHN). They identified 496 species and 147 subspecies from 111 genera, including 48 species and 8 subspecies that had previously been considered shrubs but which naturally grow into trees in the Mediterranean.
The inventory covered 39 botanical territories, defined as distinct Mediterranean areas within a country (for example, France has two such botanical territories: southern continental France and Corsica). The scientists showed that the number of endemic tree species (i.e. those that are specific to a botanical territory) varied significantly from one territory to another. For instance, Spain has 150 endemic species, while continental France has 139, Türkiye 277, Algeria 57 and Sicily 102. Data on extinction risk were lacking from the IUCN Red List[1] for nearly half the inventoried species. While no geographical trends were identified, species richness was positively correlated with the botanical territory area and habitat heterogeneity. Genetic diversity was documented for only a third of the inventoried species (mainly those of economic importance). Of the 169 species for which a genetic diversity study existed, 43% were known for at least one food- or timber-related use.
These findings and the gaps they highlight underscore the importance of stronger collaboration, as recommended in the Mediterranean Forest Research Agenda 2030 to make tree conservation efforts in Mediterranean forests more effective. The data are available through open access on the Recherche Data Gouv platform. They can be used by scientists, forest managers and other stakeholders to support national and regional conservation policies for forest genetic resources, ecological restoration and sustainable forest management.
[1] According to the International Union for Conservation of Nature, “the IUCN Red List is a critical indicator of the health of the world’s biodiversity”. Thanks to this list, we now know that one in four mammal species, one in seven birds, more than one in three amphibians and more than a third of pine species are at risk of worldwide extinction.
From left, researchers Haoze Chen, Yasaman Ghasempour, and Atsutse Kludze, have developed a system to curve ultrahigh frequency transmissions through a complex and dynamic environment.
High frequency radio waves can wirelessly carry the vast amount of data demanded by emerging technology like virtual reality, but as engineers push into the upper reaches of the radio spectrum, they are hitting walls. Literally.
Ultrahigh frequency bandwidths are easily blocked by objects, so users can lose transmissions walking between rooms or even passing a bookcase. Now, researchers at Princeton engineering have developed a machine-learning system that could allow ultrahigh frequency transmissions to dodge those obstacles. In an August 18 article in Nature Communications, the researchers unveiled a system that shapes transmissions to avoid obstacles coupled with a neural network that can rapidly adjust to a complex and dynamic environment.
Lead researcher Yasaman Ghasempour, an assistant professor of electrical and computer engineering at Princeton, said the work is an important step toward deploying data transmission in the sub-terahertz band, which is at the upper end of the microwave spectrum.
Transmissions in the sub-terahertz band have the potential to handle 10 times the data of current wireless systems. This kind of fast transmission would be important for uses such as virtual reality systems or fully autonomous vehicles.
“As our world becomes more connected and data-hungry, the demand for wireless bandwidth is soaring. Sub-terahertz frequencies open the door to far greater speeds and capacity,” Ghasempour said.
Sub-Terahertz beams are easily blocked, but can bend with special transmitters
Ultra-high frequency signals like those in the sub-terahertz band are transmitted in defined beams, unlike lower frequency radio waves, which can span over wider areas. This makes the signals easy to block, particularly indoors and in areas with lots of moving people and objects.
Engineers have successfully tested systems using reflectors to bounce signals around obstacles. But these systems rely on reflectors that may not be available or practical in many situations.
Ghasempour’s team proposed using a special transmission technique to dodge obstacles. The researchers were able to bend transmission beams by transmitting a signal that curves around the obstruction. In doing this, they used an idea first proposed in 1979 for a kind of radio wave called Airy beams that allow engineers to shape transmissions like a curveball. When correctly controlled, the beams can maneuver through a complex and moving field of objects.
“This is for complex indoor scenarios where you don’t have line of sight,” said Haoze Chen, a graduate student at Princeton and the paper’s lead author. “You want the link to adapt to that.”
Unlike static systems, the new system allows the transmitters to adapt to changes in real time. By adjusting the exact curvature properties on the fly, the transmitter can steer signals around new obstacles as they appear, maintaining a strong connection even in crowded, constantly changing environments.
Chen said that most work with Airy beams has focused on creating the beams and exploring their underlying physics.
“What we are doing is not only generating the beams but finding which beams work best in the situation,” he said. “People have shown that these beams can be created, but they have not shown how the beams can be optimized.”
The system learns to dodge obstacles by training like an NBA All-star
Finding the best curved beam is a difficult problem, particularly in a cluttered and shifting environment. The standard method of aiming beams —scanning a room for the best transmission path — does not work for bendable transmissions.
“For Airy beams, this is impractical,” Chen said. “There are infinite ways of curving depending on the degree of the curve and where the curve happens. There is no way a transmitter can scan through.”
To solve the problem, the researchers took a cue from human athletes. Basketball players don’t pull out a calculator every time they take a shot. They rely on past experience to learn what force and direction works for different situations. To generate that type of response, the researchers designed a neural net, a computer system that mimics the brain.
Like basketball players, neural nets require a lot of training before they can perform. But Chen said training the system by transmitting actual beams was very time-consuming. Instead, coauthor Atsutse Kludze designed a simulator that allowed the net to train virtually for different obstacles and different environments. The math behind Airy beams is difficult, and Kludze, a doctoral student in Ghasempour’s lab, had to create a system that applied the underlying physics to almost any scenario.
Neural net calibrates curves with perfect precision
Throwing a lot of data at the neural net is not effective. Instead, the researchers use principles from physics to create and train the neural net. Once the system was trained, the neural net was able to adapt incredibly quickly.
The researchers said they tested their scheme with experiments, which were focused on understanding the technology and developing ways to control the transmissions.
“This work tackles a long-standing problem that has prevented the adoption of such high frequencies in dynamic wireless communications to date,” Ghasempour said. “With further advances, we envision transmitters that can intelligently navigate even the most complex environments, bringing ultra-fast, reliable wireless connectivity to applications that today seem out of reach — from immersive virtual reality to fully autonomous transportation.”
The article, A Physics-Informed Airy Beam Learning Framework for Blockage Avoidance in sub-Terahertz Wireless Network, was published August 18 in the journal Nature Communications. The research was supported in part by the National Science Foundation, the Air Force Office of Scientific Research and the Qualcomm Innovation Fellowship.
The researchers used a specially designed metasurface to direct the transmissions
WASHINGTON, Aug. 18, 2025 — No matter whether it’s crushed or cubed, ice eventually melts into a puddle — but an alternative called jelly ice doesn’t. Researchers Jiahan Zou and Gang Sun developed a one-step process to create the reusable, compostable material from gelatin, the same ingredient in jiggly desserts. Because frozen jelly ice doesn’t leak as it thaws, it’s ideal for food supply chains and medication transport. The team is also exploring protein-based structures for food-safe coatings and lab-grown meat scaffolds.
Zou will present her results at the fall meeting of the American Chemical Society (ACS). ACS Fall 2025 is being held Aug. 17-21; it features about 9,000 presentations on a range of science topics.
The jelly ice project started with a question posed to Zou and Sun by Luxin Wang, a food scientist at the University of California, Davis. Wang saw ice melting in grocery store seafood display cases and worried about meltwater spreading pathogens and contaminating the entire case. She asked whether the researchers could create a reusable material that functions like regular ice but doesn’t produce a potentially contaminated puddle.
The inspiration for the new material came from freezing tofu. Sun, a materials scientist also at UC Davis who advised Zou’s graduate research, explains that “frozen tofu keeps its water inside, but when you thaw it, it releases the water. So, we tried to solve that issue with another material: gelatin.”
Gelatin proteins have two properties that the researchers wanted: They are food safe, and their long strands link together, forming hydrogels with tiny pores that hold water, unlike tofu. Early tests of the hydrogels made with this natural polymer (also called a biopolymer) were a success. The water stayed inside the pores as it went through phase changes, from liquid to ice and back again, without damaging the structures or leaking out the hydrogel.
Through the years, Zou has optimized the gelatin-based hydrogels’ formula and production methods. Now, she has a practical, one-step process to create jelly ice that’s 90% water and can be repeatedly washed with water or diluted bleach, frozen and thawed. The cooling material jiggles and squishes at room temperature. But when cooled below the freezing point of water, 32 degrees Fahrenheit (0 degrees Celsius), it transitions to a firmer, more solid state.
“Compared to regular ice of the same shape and size, jelly ice has up to 80% of the cooling efficiency — the amount of heat the gel can absorb through phase change,” says Zou, who will talk more about this when she presents the newest version of jelly ice at ACS Fall 2025. “And we can reuse the material and maintain the heat absorbance across multiple freeze-thaw cycles, so that’s an advantage compared to regular ice.”
The team can produce jelly ice in 1-pound (0.45-kilogram) slabs, similar to the cold gel packs currently for sale that have bulky plastic sleeves. However, the new cooling material has advantages over cooling packs or dry ice: It’s customizable for any shape or design, and it’s compostable. In one set of experiments, the composted gel improved tomato plant growth when applied to the potting soil. And because the cooling material doesn’t contain synthetic polymers, it shouldn’t generate microplastics.
Zou and Sun say that jelly ice, while initially developed for food preservation applications, shows promise for medical shipping, biotechnology, and use in areas with limited water available for forming ice.
Currently, there are licenses for the jelly ice technology. Zou hopes that this means the cooling material will be available to consumers as a meltwater-free, food contact-safe, compostable alternative to ice. Though, she acknowledges there are still some steps in market analysis, product design and large-scale production tests before it can be commercialized.
But as the gelatin-based jelly ice makes its way toward the market, Zou has also become interested in other natural biopolymers. She expanded her research into plant proteins that are agricultural by-products, such as soy proteins, to make more sustainable materials. Her focus is shifting toward developing soy proteins for removable countertop coatings and cellular scaffolds for cultivated meat. She’ll present more about that work at ACS Fall 2025.
“In my research, I realized how powerful Mother Nature is in designing biopolymers and the vast possibilities they offer,” says Zou. “I believe there will be amazing products derived from biopolymers as the materials themselves are teaching us how to work with them.”
The research was funded by the U.S. Department of Agriculture’s National Institute of Food and Agriculture, a Henry A. Jastro Graduate Research Award from UC Davis, and a Food Systems Innovation Award from the Innovation Institute for Food and Health at UC Davis.
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Title Sustainable bio-derived polymeric materials improving food security, food safety, and circular bioeconomy
Abstract Functional polymeric materials play a critical role in food systems, supporting processes such as post-harvest handling, processing, shipping, and retail. The development of bio-based sustainable functional materials has become a long-term goal in materials research, driven by growing concerns over global warming and plastic pollution. Agricultural byproducts, rich in biomacromolecules such as proteins and carbohydrates, represent a significant yet underutilized resource, particularly for high-value applications. Motivated by these challenges, this research focused on (1) improving the processability of natural biomacromolecules and (2) exploring their potential applications as functional materials to enhance sustainability, food security, and food safety while advancing the circular bioeconomy. Soy proteins were studied as a model biomacromolecule requiring improved processability, using physical (e.g., ultrasound and high-speed shearing) and chemical (e.g., pH adjustments and plasticizer incorporation) treatments. Synergistic effects from combined approaches demonstrated potential for broader biomacromolecule processing. Three proof-of-concept sustainable materials were developed, showcasing the potential of bio-based functional polymeric materials to benefit food and agricultural systems: 1) a type of novel reusable cooling media (“Jelly Ice Cubes”) designed from gelatin hydrogels, offering customizable cooling, elimination of meltwater, reusability, microbial resistance, and compostability; 2) a removable coating was developed to combat bacterial contamination and prevent biofilm formation on hydrophobic food-contact surfaces; and 3) the scaffolding materials for the future sustainable food developed via cellular agriculture. These innovations highlight the transformative role of bio-based functional materials in addressing critical challenges within food systems by promoting sustainability, reducing waste, and enhancing food security and safety.
