Led by Jagan Jayachandran, assistant professor of aerospace engineering, and Adam Powell, associate professor of mechanical and materials engineering, the work helps address an urgent climate change problem. Aviation accounts for approximately 2.5% of all global greenhouse emissions, according to the International Council on Clean Transportation (ICCT), and that number is only expected to increase.

“As aviation continues to grow, so will the industry’s emissions, says Powell. “We need to think out of the box and look at sustainable materials that will contribute to a long-term solution toward reducing the transportation sector’s carbon footprint.”

Through modeling and computation analysis, Jayachandran and Powell developed a formula for a fuel that consists of magnesium, a mineral that is found all over the globe, most abundantly in the world’s oceans. A slurry of magnesium hydride — a chemical compound made up of magnesium and hydrogen — mixed with hydrocarbon fuel would burn to produce CO₂, water vapor and magnesium oxide (MgO) nanoparticles. The magnesium hydride fuel would also give planes the range for long-haul flights — e.g., from Boston to Tokyo — something that has been a challenge for other sustainable aviation fuels to provide. That longer range is achieved, in part, due to the chemical properties of the slurry — a lower volume of it is needed for combustion than a typical aviation fuel.

“We found this fuel would have up to 8% more range than other today’s jet fuel, and more than two to three times longer range than liquid hydrogen or ammonia which other researchers have proposed as sustainable fuels,” said Jayachandran.

The Department of Energy describes a sustainable aviation fuel as a “biofuel used to power aircraft that has similar properties to conventional jet fuel but with a smaller carbon footprint.” These biofuels have been made from resources including corn grain, algae, forestry, and agricultural residues, among others. Using a biofuel as the hydrocarbon in this slurry with magnesium hydride could potentially lead to net negative emissions.

The research was supported by a WPI TRIAD Seed Grant, a university award intended to encourage and promote interdisciplinary collaboration and innovation.

Jayachandran and Powell plan to further their research through physical experiments with samples of the fuel, and are also pursuing potential funding from a federal agency. In addition, they hope this work can inspire others and contribute to a more sustainable world.

Noting the promise of research to mitigate emissions and other climate threats, Powell said, “we hope our work, which opens up a new category of sustainable aviation fuel will spark the imagination of other researchers. The sky’s the limit.”

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Materials provided by Worcester Polytechnic Institute. Note: Content may be edited for style and length.

Using data from India’s SARAS3 radio telescope, researchers led by the University of Cambridge were able to look at the very early Universe — just 200 million years after the Big Bang — and place limits on the mass and energy output of the first stars and galaxies.

Counterintuitively, the researchers were able to place these limits on the earliest galaxies by not finding the signal they had been looking for, known as the 21-centimetre hydrogen line.

This non-detection allowed the researchers to make other determinations about the cosmic dawn, placing restraints on the first galaxies, enabling them to rule out scenarios including galaxies which were inefficient heaters of cosmic gas and efficient producers of radio emissions.

While we cannot yet directly observe these early galaxies, the results, reported in the journal Nature Astronomy, represent an important step in understanding how our Universe transitioned from mostly empty to one full of stars.

Understanding the early Universe, when the first stars and galaxies formed, is one of the major goals of new observatories. The results obtained using the SARAS3 data are a proof-of-concept study that paves the way to understanding this period in the development of the Universe.

The SKA project — involving two next-generation telescopes due to be completed by the end of the decade — will likely be able to make images of the early Universe, but for current telescopes the challenge is to detect the cosmological signal of the first stars re-radiated by thick hydrogen clouds.

This signal is known as the 21-centimetre line — a radio signal produced by hydrogen atoms in the early Universe. Unlike the recently launched JWST, which will be able to directly image individual galaxies in the early Universe, studies of the 21-centimetre line, made with radio telescopes such as the Cambridge-led REACH (Radio Experiment for the Analysis of Cosmic Hydrogen), can tell us about entire populations of even earlier galaxies. The first results are expected from REACH early in 2023.

To detect the 21-centimetre line, astronomers look for a radio signal produced by hydrogen atoms in the early Universe, affected by light from the first stars and the radiation behind the hydrogen fog. Earlier this year, the same researchers developed a method which they say will allow them to see through the fog of the early universe and detect light from the first stars. Some of these techniques have been already put to practice in the current study.

In 2018, another research group operating the EDGES experiment published a result that hinted at a possible detection of this earliest light. The reported signal was unusually strong compared to what is expected in the simplest astrophysical picture of the early Universe. Recently, the SARAS3 data disputed this detection: the EDGES result is still awaiting confirmation from independent observations.

In a re-analysis of the SARAS3 data, the Cambridge-led team tested a variety of astrophysical scenarios which could potentially explain the EDGES result, but they did not find a corresponding signal. Instead, the team was able to place some limits on properties of the first stars and galaxies.

The results of the SARAS3 analysis are the first time that radio observations of the averaged 21-centimetre line have been able to provide an insight to the properties of the first galaxies in the form of limits of their main physical properties.

Working with collaborators in India, Australia and Israel, the Cambridge team used data from the SARAS3 experiment to look for signals from cosmic dawn, when the first galaxies formed. Using statistical modelling techniques, the researchers were not able to find a signal in the SARAS3 data.

“We were looking for a signal with a certain amplitude,” said Harry Bevins, a PhD student from Cambridge’s Cavendish Laboratory and the paper’s lead author. “But by not finding that signal, we can put a limit on its depth. That, in turn, begins to inform us about how bright the first galaxies were.”

“Our analysis showed that the hydrogen signal can inform us about the population of first stars and galaxies,” said co-lead author Dr Anastasia Fialkov from Cambridge’s Institute of Astronomy. “Our analysis places limits on some of the key properties of the first sources of light including the masses of the earliest galaxies and the efficiency with which these galaxies can form stars. We also address the question of how efficiently these sources emit X-ray, radio and ultraviolet radiation.”

“This is an early step for us in what we hope will be a decade of discoveries about how the Universe transitioned from darkness and emptiness to the complex realm of stars, galaxies and other celestial objects we can see from Earth today,” said Dr Eloy de Lera Acedo from Cambridge’s Cavendish Laboratory, who co-led the research.

The observational study, the first of its kind in many respects, excludes scenarios in which the earliest galaxies were both more than a thousand times as bright as present galaxies in their radio-band emission and were poor heaters of hydrogen gas.

“Our data also reveals something which has been hinted at before, which is that the first stars and galaxies could have had a measurable contribution to the background radiation that appeared as a result of the Big Bang and which has been travelling towards us ever since,” said de Lera Acedo, “We are also establishing a limit to that contribution.”

“It’s amazing to be able to look so far back in time — to just 200 million years after the Big Bang- and be able to learn about the early Universe,” said Bevins.

The research was supported in part by the Science and Technology Facilities Council (STFC), part of UK Research & Innovation (UKRI), and the Royal Society. The Cambridge authors are all members of the Kavli Institute for Cosmology in Cambridge.

Animals also have personalities

Red knots of all ages and sexes show behavioural traits. These remain mostly unchanged over time but differ across individuals. Some individuals are more adventurous and show more exploratory behaviours a in new environment than others. Other individuals take less risks and hardly dare to move around in a new environment. These ‘personalities’ have ecological and evolutionary consequences, but to what extent is largely unknown, because few studies have investigated this in the field.

During her PhD research Selin Ersoy has developed a new way of identifying the variation in personality between individual red knots. She wanted to know if the behaviour in experimental settings could be extrapolated to a larger and more complex natural setting, and how individual differences develop.

“With our new method that allowed studying animal personality in the wild, we found that red knots develop their personality probably through the experience that they get when growing up ,” says Ersoy. “After growing up, adults stick with exploratory behaviours. They seem to be like character types in humans.”

Explorers eat higher quality food

It was even possible for Ersoy and her colleagues to predict a suit of other behaviours in the wild. For instance, variation in explorative personality type (i.e., slow vs. fast explorer) predicts foraging tactics and dietary choice in the wild. Fast explorers use more visual foraging and eat soft prey such as shrimp or worms, while slow explorers use tactile foraging and feed on hard-shelled prey such as cockles. This is a new explanation for variation in foraging niche specialisation between individuals in the same population.

Exploratory behaviour also relates to variation in movement across the landscape and over time. Ersoy: “We were amazed to see that slow and fast explorers have clearly different movement patterns during the night, while at day they moved more or less the same way. These different individuals even have different arrival times from migration. Fast explorers arrive to the Wadden Sea later than the slower explorers.” Ersoy and her colleagues want to study next where they stay in the meantime. Maybe these red knots take more time to care for their youngs in the Arctic.

The whole group benefits

“We found striking differences in feeding and movement patterns between slow and fast exploring red knots. This suggests that fast explorers might provide foraging information and new foraging opportunities for entire populations,” says Ersoy. “Such new opportunities are important because red knots face pressures from human impact on their coastal wintering habitats, directly related to availability of food. Fast explorers can help the entire population to cope with environmental change.”

Gap closed between controlled experiments and real Wadden Sea

The goal of determining behaviour in experimental setups is to understand the mechanisms behind the behaviour in the wild. Selin Ersoy’s study fills a critical gap between experimental research on wild animals in controlled environments and observed behaviour in the wild.

“It’s a first step. We need to do similar personality research on other animals and on other natural habitats,” says Ersoy. “We want to know if personalities work the same in other species and situations.”

Tracking movements of guillemots with tiny transmitters

Researchers like Selin Ersoy track birds using ultra-small radio transmitters placed on their backs during the summer months. Birds are not bothered by them. Those transmitters send out unique signals. These are received by antennas scattered throughout the Wadden Sea.

Reverse GPS

WATLAS is a new system that makes use of so-called ‘reverse-GPS’. The tiny transmitters that are temporarily attached to birds transmit a signal of their own. That signal is received by fixed receiving stations in and around the Wadden Sea. Due to the tiny differences in the time of arrival of the signal between different receivers, the position of the animal-with-transmitter is calculated to the accuracy of a few meters, from second to second.

Thanks to WATLAS, researchers can watch a migratory bird such as the red knot move back and forth with low and high tide very precisely in search of food. Because many birds can be fitted with the relatively inexpensive transmitters at the same time, researchers can now see interactions between different animals happening from the comfort of their office chairs.