It is the year 1181 and in Japan the Genpei War (1180-85) has recently begun. It will lead to a shift in political power from aristocratic families to the new military-based shogunate, which will establish itself in the coastal city of Kamakura near modern-day Tokyo. A record of this tumultuous period was compiled in a diary format in the Azuma Kagami. It chronicled not only people’s lives and key events (with varying accuracy), but other daily observations, including the appearance of a new star.

“There are many accounts of this temporary guest star in historical records from Japan, China and Korea. At its peak, the star’s brightness was comparable to Saturn’s. It remained visible to the naked eye for about 180 days, until it gradually dimmed out of sight. The remnant of the SN 1181 explosion is now very old, so it is dark and difficult to find,” explained lead author Takatoshi Ko, a doctoral student from the Department of Astronomy at the University of Tokyo.

The remnant of this guest star, labeled supernova remnant (SNR) 1181, was found to have been created when two extremely dense, Earth-sized stars, called white dwarfs, collided. This created a rare type of supernova, called a Type Iax supernova, which left behind a single, bright and fast-rotating white dwarf. Aided by observations on its position noted in the historical document, modern astrophysicists finally pinpointed its location in 2021 in a nebula towards the constellation Cassiopeia.

Due to its rare nature and location within our galaxy, SNR 1181 has been the subject of much observational research. This suggested that SNR 1181 is made up of two shock regions, an outer region and an inner one. In this new study, the research group analyzed the latest X-ray data to construct a theoretical computer model to explain these observations, and which has recreated the previously unexplained structure of this supernova remnant.

The main challenge was that according to conventional understanding, when two white dwarfs collide like this, they should explode and disappear. However, this merger left behind a white dwarf. The spinning white dwarf was expected to create a stellar wind (a fast-flowing stream of particles) immediately after its formation. However, what the researchers found was something else.

“If the wind had started blowing immediately after SNR 1181’s formation, we couldn’t reproduce the observed size of the inner shock region,” said Ko. “However, by treating the wind’s onset time as variable, we succeeded in explaining all of the observed features of SNR 1181 accurately and unraveling the mysterious properties of this high-speed wind. We were also able to simultaneously track the time evolution of each shock region, using numerical calculations.”

The team was very surprised to find that according to their calculations, the wind may have started blowing only very recently, within the past 20-30 years. They suggest this may indicate that the white dwarf has started to burn again, possibly due to some of the matter thrown out by the explosion witnessed in 1181 falling back to its surface, increasing its density and temperature over a threshold to restart burning.

To validate their computer model, the team is now preparing to further observe SNR 1181 using the Very Large Array (VLA) radio telescope based in central New Mexico state in the U.S., and the 8.2 meter-class Subaru Telescope in the U.S. state of Hawaii.

“The ability to determine the age of supernova remnants or the brightness at the time of their explosion through archaeological perspectives is a rare and invaluable asset to modern astronomy,” said Ko. “Such interdisciplinary research is both exciting and highlights the immense potential for combining diverse fields to uncover new dimensions of astronomical phenomena.”

Their method involves mixing bacteria with food and drug additives from a list of compounds that the FDA classifies as “generally regarded as safe.” The researchers identified formulations that help to stabilize several different types of microbes, including yeast and bacteria, and they showed that these formulations could withstand high temperatures, radiation, and industrial processing that can damage unprotected microbes.

In an even more extreme test, some of the microbes recently returned from a trip to the International Space Station, coordinated by Space Center Houston Manager of Science and Research Phyllis Friello, and the researchers are now analyzing how well the microbes were able to withstand those conditions.

“What this project was about is stabilizing organisms for extreme conditions. We’re really thinking about a broad set of applications, whether it’s missions to space, human applications, or agricultural uses,” says Giovanni Traverso, an associate professor of mechanical engineering at MIT, a gastroenterologist at Brigham and Women’s Hospital, and the senior author of the study.

Miguel Jimenez, a former MIT research scientist who is now an assistant professor of biomedical engineering at Boston University, is the lead author of the paper, which will appear in Nature Materials.

Surviving extreme conditions

About six years ago, with funding from NASA’s Translational Research Institute for Space Health (TRISH), Traverso’s lab began working on new approaches to make helpful bacteria such as probiotics and microbial therapeutics more resilient. As a starting point, the researchers analyzed 13commercially available probiotics and found that six of these products did not contain as many live bacteria as the label indicated.

“What we found was that, perhaps not surprisingly, there is a difference, and it can be significant,” Traverso says. “So then the next question was, given this, what can we do to help the situation?”

For their experiments, the researchers chose four different microbes to focus on: three bacteria and one yeast. These microbes are Escherichia coli Nissle 1917, a probiotic; Ensifer meliloti, a bacterium that can fix nitrogen in soil to support plant growth; Lactobacillus plantarum, a bacterium used to ferment food products; and the yeast Saccharomyces boulardii, which is also used as a probiotic.

When microbes are used for medical or agricultural applications, they are usually dried into a powder through a process called lyophilization. However, they can not normally be made into more useful forms such as a tablet or pill because this process requires exposure to an organic solvent, which can be toxic to the bacteria. The MIT team set out to find additives that could improve the microbes’ ability to survive this kind of processing.

“We developed a workflow where we can take materials from the ‘generally regarded as safe’ materials list from the FDA, and mix and match those with bacteria and ask, are there ingredients that enhance the stability of the bacteria during the lyophilization process?” Traverso says.

Their setup allows them to mix microbes with one of about 100 different ingredients and then grow them to see which survive the best when stored at room temperature for 30 days. These experiments revealed different ingredients, mostly sugars and peptides, that worked best for each species of microbe.

The researchers then picked one of the microbes, E. coli Nissle 1917, for further optimization. This probiotic has been used to treat “traveler’s diarrhea,” a condition caused by drinking water contaminated with harmful bacteria. The researchers found that if they combined caffeine or yeast extract with a sugar called melibiose, they could create a very stable formulation of E. coli Nissle 1917. This mixture, which the researchers called formulation D, allowed survival rates greater than 10 percent after the microbes were stored for six months at 37 degrees Celsius, while a commercially available formulation of E. coli Nissle 1917 lost all viability after only 11 days under those conditions.

Formulation D was also able to withstand much higher levels of ionizing radiation, up to 1,000 grays. (The typical radiation dose on Earth is about 15 micrograys per day, and in space, it’s about 200 micrograys per day.)

The researchers don’t know exactly how their formulations protect bacteria, but they hypothesize that the additives may help to stabilize the bacterial cell membranes during rehydration.

Stress tests

The researchers then showed that these microbes can not only survive harsh conditions, they also maintain their function after these exposures. After Ensifer meliloti were exposed to temperatures up to 50 degrees Celsius, the researchers found that they were still able to form symbiotic nodules on plant roots and convert nitrogen to ammonia.

They also found that their formulation of E. coli Nissle 1917 was able to inhibit the growth of Shigella flexneri, one of the leading causes of diarrhea-associated deaths in low- and middle-income countries, when the microbes were grown together in a lab dish.

Last year, several strains of these extremophile microbes were sent to the International Space Station, which Jimenez describes as “the ultimate stress test.”

“Even just the shipping on Earth to the preflight validation, and storage until flight are part of this test, with no temperature control along the way,” he says.

The samples recently returned to Earth, and Jimenez’ lab is now analyzing them. He plans to compare samples that were kept inside the ISS to others that were bolted to the outside of the station, as well as control samples that remained on Earth.

The research was funded by NASA’s Translational Research Institute for Space Health, Space Center Houston, MIT’s Department of Mechanical Engineering, and by 711 Human Performance Wing and the Defense Advanced Research Projects Agency.

Other authors of the paper include Johanna L’Heureux, Emily Kolaya, Gary Liu, Kyle Martin, Husna Ellis, Alfred Dao, Margaret Yang, Zachary Villaverde, Afeefah Khazi-Syed, Qinhao Cao, Niora Fabian, Joshua Jenkins, Nina Fitzgerald, Christina Karavasili, Benjamin Muller, and James Byrne.

The question of how migratory birds locate their migration routes has intrigued humankind for centuries. Biologist Albert Perdeck from the Netherlands aimed to find answers when he displaced thousands of migrating starlings by plane from the Netherlands to Switzerland and Spain in the 1950’s and 1960’s. This experiment has become a classic study on the migratory orientation of birds. Now, seventy years later, colleagues have confirmed his findings and were able to solve a long-lasting scientific debate using this historical dataset.

Young vs. adult

The birds were individually recognisable using light-weight metal leg rings with a unique code — a method used by the Dutch Centre for Avian Migration and Demography, Vogelwarte Sempach and European partners until this day. Ring recoveries indicated that relocated young and adult starlings used different strategies to reach the winter destinations in the British Isles and France. “Adult starlings were aware of this move and adjusted their migratory orientation to reach their normal wintering areas,” according to Morrison Pot at the NIOO-KNAW. “Young starlings continued in a south-westerly direction — the direction they would have chosen when departing from the Netherlands — and reached ‘wrong’ destinations in southern France and Spain.”

New friends?

Over the years, experts in the field of avian migration have been divided about the interpretation of Perdeck’s results. Pot: “Starlings are highly social animals and, according to some experts, the relocated young starlings may just as well have joined a flock of local conspecifics.” The relocated starlings would have copied the migratory behaviour of their new friends showing them where to go. “If true, the migratory route is largely learned instead of inherited.” A major difference.

The team of researchers retrieved the historical data of Perdeck’s displacement experiments in the paper archives of the Dutch Centre for Avian Migration and Demography and compared the migratory orientation with the migratory behaviour of local Swiss and Spanish starlings. “The latter data were retrieved from institutional archives, but were unavailable in Perdeck’s days.”

Social migrants

By re-analysing this historical dataset, the team showed that the migratory orientation of the relocated starlings differed from the local conspecifics. Starlings are thus no social migrants or ‘copycats’. The alternative social explanation of Perdeck’s results has thus been debunked. As explained by Pot: “Starlings travel independently and decisions about where to go are not overruled by the migratory behaviour of others.” Recently, a study in collaboration with Vogelwarte Sempach showed that starlings migrate at night. This is in line with the 70-year-old findings, because how would you follow someone in the pitch darkness of the night?

Times of change

Learned or inherited behaviour, why does it matter? “In times of rapid changes in global climate and land-use, it is of great importance to understand whether migratory behaviour is largely inherited or learned,” says lead scientist and head of the Dutch Centre for Avian Migration and Demography Henk van der Jeugd. Inherited behaviours are less flexible to rapid change. “Although starlings are numerous and widespread birds that have adjusted to human dominated landscapes, their migratory behaviour is likely less flexible.”

At present, there is still one crucial drawback with lithium metal batteries: the liquid electrolyte requires the addition of significant amounts of fluorinated solvents and fluorinated salts, which increases its environmental footprint. Without the addition of fluorine, however, lithium metal batteries would be unstable, they would stop working after very few charging cycles and be prone to short circuits as well as overheating and igniting. A research group led by Maria Lukatskaya, Professor of Electrochemical Energy Systems at ETH Zurich, has now developed a new method that dramatically reduces the amount of fluorine required in lithium metal batteries, thereby rendering them more environmentally friendly and more stable as well as cost-effective.

A stable protective layer increases battery safety and efficiency

The fluorinated compounds from electrolyte help the formation of a protective layer around the metallic lithium at the negative electrode of the battery. “This protective layer can be compared to the enamel of a tooth,” Lukatskaya explains. “It protects the metallic lithium from continuous reaction with electrolyte components.” Without it, the electrolyte would quickly get depleted during cycling, the cell would fail, and the lack of a stable layer would result in the formation of lithium metal whiskers — ‘dendrites’ — during the recharging process instead of a conformal flat layer.

Should these dendrites touch the positive electrode, this would cause a short circuit with the risk that the battery heats up so much that it ignites. The ability to control the properties of this protective layer is therefore crucial for battery performance. A stable protective layer increases battery efficiency, safety and service life.

Minimising fluorine content

“The question was how to reduce the amount of added fluorine without compromising the protective layer’s stability,” says doctoral student Nathan Hong. The group’s new method uses electrostatic attraction to achieve the desired reaction. Here, electrically charged fluorinated molecules serve as a vehicle to transport the fluorine to the protective layer. This means that only 0.1 percent by weight of fluorine is required in the liquid electrolyte, which is at least 20 times lower than in prior studies.

Optimised method makes batteries greener

The ETH Zurich research group describes the new method and its underlying principles in a paper recently published in the journal Energy & Environmental Science. An application for a patent has been made.

One of the biggest challenges was to find the right molecule to which fluorine could be attached and that would also decompose again under the right conditions once it had reached the lithium metal. As the group explains, a key advantage of this method is that it can be seamlessly integrated into the existing battery production process without generating additional costs to change the production setup. The batteries used in the lab were the size of a coin. In a next step, the researchers plan to test the method’s scalability and apply it to pouch cells as used in smartphones.

Researchers in EPFL’s Laboratory of Nanoscale Electronics and Structures (LANES), led by Andras Kis, in the School of Engineering have now fabricated a device that not only operates at extremely low temperatures, but does so with efficiency comparable to current technologies at room temperature.

“We are the first to create a device that matches the conversion efficiency of current technologies, but that operates at the low magnetic fields and ultra-low temperatures required for quantum systems. This work is truly a step ahead,” says LANES PhD student Gabriele Pasquale.

The innovative device combines the excellent electrical conductivity of graphene with the semiconductor properties of indium selenide. Only a few atoms thick, it behaves as a two-dimensional object, and this novel combination of materials and structure yields its unprecedented performance. The achievement has been published in Nature Nanotechnology.

Harnessing the Nernst effect

The device exploits the Nernst effect: a complex thermoelectric phenomenon that generates an electrical voltage when a magnetic field is applied perpendicular to an object with a varying temperature. The two-dimensional nature of the lab’s device allows the efficiency of this mechanism to be controlled electrically.

The 2D structure was fabricated at the EPFL Center for MicroNanoTechnology and the LANES lab. Experiments involved using a laser as a heat source, and a specialized dilution refrigerator to reach 100 millikelvin — a temperature even colder than outer space. Converting heat to voltage at such low temperatures is usually extremely challenging, but the novel device and its harnessing of the Nernst effect make this possible, filling a critical gap in quantum technology.

“If you think of a laptop in a cold office, the laptop will still heat up as it operates, causing the temperature of the room to increase as well. In quantum computing systems, there is currently no mechanism to prevent this heat from disturbing the qubits. Our device could provide this necessary cooling,” Pasquale says.

A physicist by training, Pasquale emphasizes that this research is significant because it sheds light on thermopower conversion at low temperatures — an underexplored phenomenon until now. Given the high conversion efficiency and the use of potentially manufacturable electronic components, the LANES team also believes their device could already be integrated into existing low-temperature quantum circuits.

“These findings represent a major advancement in nanotechnology and hold promise for developing advanced cooling technologies essential for quantum computing at millikelvin temperatures,” Pasquale says. “We believe this achievement could revolutionize cooling systems for future technologies.”

Around 34 million years ago, our planet underwent one of the most fundamental climate shifts that still influences global climate conditions today: the transition from a greenhouse world, with no or very little accumulation of continental ice, to an icehouse world, with large permanently glaciated areas. During this time, the Antarctic ice sheet built up. How, when and, above all, where, was not yet known due to a lack of reliable data and samples from key regions, especially from West Antarctica, that document the changes in the past. Researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now been able to close this knowledge gap, together with colleagues from the British Antarctic Survey, Heidelberg University, Northumbria University (UK), and the MARUM — Center for Marine Environmental Sciences at the University of Bremen, in addition to collaborators from the Universities in Aachen, Leipzig, Hamburg, Bremen, and Kiel, as well as the University of Tasmania (Australia), Imperial College London (UK), Université de Fribourg (Switzerland), Universidad de Granada (Spain), Leicester University (UK), Texas A&M University (USA), Senckenberg am Meer, and the Federal Institute for Geosciences and Natural Resources in Hanover, Germany.

Based on a drill core that the researchers retrieved using the MARUM-MeBo70 seafloor drill rig in a location offshore the Pine Island and Thwaites glaciers on the Amundsen Sea coast of West Antarctica, they were able to establish the history of the dawn of the icy Antarctic continent for the first time. Surprisingly, no signs of the presence of ice can be found in this region during the first major phase of Antarctic glaciation. “This means that a large-scale, permanent first glaciation must have begun somewhere in East Antarctica,” says Dr Johann Klages, geologist at the AWI who led the research team. This is because West Antarctica remained ice-free during this first glacial maximum. At this time, it was still largely covered by dense broadleaf forests and a cool-temperate climate that prevented ice from forming in West Antarctica.

East and West Antarctica react very different to external conditions

In order to better understand where the first permanent ice formed in Antarctica, the AWI paleoclimate modelers combined the newly available data together with existing data on air and water temperatures and the occurrence of ice. “The simulation has supported the results of the geologists’ unique core,” says Prof Dr Gerrit Lohmann, paleoclimate modeler at the AWI. “This completely changes what we know about the first Antarctic glaciation.” According to the study, the basic climatic conditions for the formation of permanent ice only prevailed in the coastal regions of the East Antarctic Northern Victoria Land. Here, moist air masses reached the strongly rising Transantarctic Mountains — ideal conditions for permanent snow and subsequent formation of ice caps. From there, the ice sheet spread rapidly into the East Antarctic hinterland. However, it took some time before it reached West Antarctica: “It wasn’t until about seven million years later that conditions allowed for advance of an ice sheet to the West Antarctic coast,” explains Hanna Knahl, a paleoclimate modeler at the AWI. “Our results clearly show how cold it had to get before the ice could advance to cover West Antarctica that, at that time, was already below sea level in many parts.” What the investigations also impressively show is how different the two regions of the Antarctic ice sheet react to external influences and fundamental climatic changes. “Even a slight warming is enough to cause the ice in West Antarctica to melt again — and that’s exactly where we are right now,” adds Johann Klages.

The findings of the international research team are critical for understanding the extreme climate transition from the greenhouse climate to our current icehouse climate. Importantly, the study also provides new insight that allows climate models to simulate more accurately how permanently glaciated areas affect global climate dynamics, that is the interactions between ice, ocean and atmosphere. This is of crucial importance, as Johann Klages says: “Especially in light of the fact that we could be facing such a fundamental climate change again in the near future.”

Using new technology to gain unique insights

The researchers were able to close this knowledge gap with the help of a unique drill core that they retrieved during the expedition PS104 on the research vessel Polarstern in West Antarctica in 2017. The MARUM-MeBo70 drill rig developed at MARUM in Bremen was used for the first time in Antarctica. The seabed off the West Antarctic Pine Island and Thwaites glaciers is so hard that it was previously impossible to reach deep sediments using conventional drilling methods. The MARUM-MeBo70 has a rotating cutterhead, which made it possible to drill about 10 meters into the seabed and retrieve the samples.

The research project, and the Polarstern expedition PS104 in particular, was funded by the AWI, MARUM, the British Antarctic Survey, and the NERC UK-IODP Programme.

These DNA pieces came to be known as “selfish genetic elements” because they exist, as far as scientists could tell, to simply reproduce and propagate themselves, without any benefit to their host organisms. They were seen as genetic hitchhikers that have been inconsequentially passed from one generation to the next.

Research conducted by scientists at the University of California San Diego has provided fresh evidence that such DNA elements might not be so selfish after all. Instead, they now appear to factor considerably into the dynamics between competing organisms.

Publishing in the journal Science, researchers in the School of Biological Sciences studied selfish genetic elements in bacteriophages (phages), viruses that are considered the most abundant organisms on Earth. To their surprise, researchers found that selfish genetic elements known as “mobile introns” provide their virus hosts with a clear advantage when competing with other viruses: phages have weaponized mobile introns to disrupt the ability of competing phage viruses to reproduce.

“This is the first time a selfish genetic element has been demonstrated to confer a competitive advantage to the host organism it has invaded,” said study co-first author Erica Birkholz, a postdoctoral scholar in the Department of Molecular Biology. “Understanding that selfish genetic elements are not always purely ‘selfish’ has wide implications for better understanding the evolution of genomes in all kingdoms of life.”

Decades ago biologists noted the existence of selfish genetic elements but were unable to characterize any role they play in helping the host organism survive and reproduce. In the new study, which focused on investigating “jumbo” phages, the researchers analyzed the dynamics as two phages co-infect a single bacterial cell and compete against each other.

They looked closely at the endonuclease, an enzyme that serves as a DNA cutting tool. The endonuclease from one phage’s mobile intron, the studies showed, interferes with the genome of the competing phage. The endonuclease therefore is now regarded as a combat tool since it has been documented cutting an essential gene in the competing phage’s genome. This sabotages the competitor’s ability to appropriately assemble its own progeny and reproduce.

“This weaponized intron endonuclease gives a competitive advantage to the phage carrying it,” said Birkholz.

The researchers say the finding is especially important in the evolutionary arms race between viruses due to the constant competition in co-infection.

“We were able to clearly delineate the mechanism that gives an advantage and how that happens at the molecular level,” said Biological Sciences graduate student Chase Morgan, the paper’s co-first author. “This incompatibility between selfish genetic elements becomes molecular warfare.”

The results of the study are important as phage viruses emerge as therapeutic tools in the fight against antibiotic resistant bacteria. Since doctors have been deploying “cocktails” of phage to combat infections in this growing crisis, the new information is likely to come into play when multiple phage are implemented. Knowing that certain phage are using selfish genetic elements as weapons against other phage could help researchers understand why certain combinations of phage may not reach their full therapeutic potential.

“The phages in this study can be used to treat patients with bacterial infections associated with cystic fibrosis,” said Biological Sciences Professor Joe Pogliano. “Understanding how they compete with one another will allow us to make better cocktails for phage therapy.”

The authors of the paper are: Erica Birkholz, Chase Morgan, Thomas Laughlin, Rebecca Lau, Amy Prichard, Sahana Rangarajan, Gabrielle Meza, Jina Lee, Emily Armbruster, Sergey Suslov, Kit Pogliano, Justin Meyer, Elizabeth Villa, Kevin Corbett and Joe Pogliano.

The research detailed in the Science study was funded by an Emerging Pathogens Initiative grant from the Howard Hughes Medical institute, the National Institutes of Health (R01- GM129245 and R35 GM144121) and the National Science Foundation (MRI grant NSF DBI 1920374).

Competing interest disclosure: Professors Kit and Joe Pogliano have an equity interest in Linnaeus Bioscience Inc. and receive income.