The research team led by Professor Jee-hoon Han from the Department of Chemical Engineering at POSTECH collaborated with Director Ji Hoon Park, Principal Researcher Soo Min Kim, and Researcher Myungho Choi from CO₂ & Energy Research Center at the Korea Research Institute of Chemical Technology, and Chonnam National University Professor Jaewon Byun to create a process technology for the efficient synthesis and purification of ionic liquids. Their research was recently featured as the cover paper in the online edition of Industrial & Engineering Chemistry Research (I&EC Research), an international journal in the field of chemical engineering.

Ionic liquids are salts that remain in a liquid state at room temperature or even at relatively low temperatures due to strong electrical interactions between their ions. Unlike common salts, they possess unique properties such as nonflammability, low volatility, and thermal and chemical stability, making them valuable for various industrial applications including catalysts and electrolytes.

One of the most studied ionic liquids is [bmim][BF₄], known for its high stability and low toxicity. However, the complex and expensive process of removing impurities such as lithium chloride (LiCl) during synthesis has been a significant barrier to the technology’s commercialization.

In this study, the researchers employed halocarbon refrigerants — specifically, chlorodifluoromethane (Rf-22) — to synthesize the ionic liquid [bmim][BF₄] more economically and efficiently than traditional methods. By using Rf-22 as a phase separation mediator, they were able to induce a mixture containing methylimidazole to separate into two distinct layers, similar to the separation of oil and water.

The team observed phase separation by varying the ratios of [bmim][BF₄], water, and halocarbon mixtures. They then applied the collected data to a ternary phase diagram model. This model visually represents the composition and phases of a mixture containing three different components and is used to predict the phase formed based on the proportions of each ingredient.

Using the ternary phase diagram modeling, the researchers successfully produced high-purity [bmim][BF₄] with a purity exceeding 99%. Additionally, they were able to effectively recover and recycle the layer containing methylimidazole which did not participate in the synthesis reaction.

The team then conducted process simulations to evaluate the economic feasibility of the purification technology developed in this study. Based on a cost analysis for producing 1 ton of [bmim][BF₄] per day, they determined that the minimum selling price would be about $12,000 per ton. This is more competitive than existing process technologies, demonstrating the potential for commercializing the technology.

Professor Jee-hoon Han of POSTECH stated, “We hope this research will advance the commercialization of ionic liquids and provide practical industrial solutions based on our understanding of these substances.” Principal Researcher Soo Min Kim from the Korea Research Institute of Chemical Technology expressed the significance of the research by saying, “This technique can also be applied to other solvents, enabling the synthesis of a wide range of high-purity ionic liquids.”

The research was conducted with support the Young Researcher Program of the Ministry of Science and ICT and the Basic Program of Korea Research Institute of Chemical Technology.

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.