Science

Carbon in the atmosphere is a major driver of climate change. Now researchers from McGill University have designed a new catalyst for converting carbon dioxide (CO₂) into methane—a cleaner source of energy—using tiny bits of copper called nanoclusters. While the traditional method of producing methane from fossil fuels introduces more CO₂ into the atmosphere, the new process, electrocatalysis, does not.

“On sunny days you can use solar power, or when it’s a windy day you can use that wind to produce renewable electricity, but as soon as you produce that electricity you need to use it,” says Mahdi Salehi, Ph.D. candidate at the Electrocatalysis Lab at McGill University. “But in our case, we can use that renewable but intermittent electricity to store the energy in chemicals like methane.”

By using copper nanoclusters, says Salehi, carbon dioxide from the atmosphere can be transformed into methane and once the methane is used, any carbon dioxide released can be captured and “recycled” back into methane. This would create a closed “carbon loop” that does not emit new carbon dioxide into the atmosphere. The research, published recently in the journal Applied Catalysis B: Environment and Energy, was enabled by the Canadian Light Source (CLS) at the University of Saskatchewan (USask).

“In our simulations, we used copper catalysts with different sizes, from small ones with only 19 atoms to larger ones with 1000 atoms,” says Salehi. “We then tested them in the lab, focusing on how the sizes of the clusters influenced the reaction mechanism.”

“Our top finding was that extremely small copper nanoclusters are very effective at producing methane,” continues Salehi. “This was a significant discovery, indicating that the size and structure of the copper nanoclusters play a crucial role in the reaction’s outcome.”

The team plans to continue refining their catalyst to make it more efficient and investigate its large-scale, industrial applications. Their hope is that their findings will open new avenues for producing clean, sustainable energy.

Offering a foretaste of what’s to come once it is fully commissioned, ESA’s EarthCARE satellite has returned the first images from its broadband radiometer instrument. These initial images offer a tantalizing glimpse into the intricacies of our planet’s energy balance—a delicate balance that governs our climate.

Earth’s energy balance accounts the amount of energy it receives from the sun, solar radiation, and the amount of thermal radiation that Earth emits back out to space.

Influenced by numerous factors, including clouds, aerosols and greenhouse gases, this balance is vital for maintaining Earth’s relatively stable temperatures.

Although it is well-known that human activities are increasing greenhouse gas concentrations in the atmosphere, aerosols also enter the atmosphere from industrial plants, traffic and agricultural practices, as well as from natural sources.

Global temperatures are rising, so understanding and monitoring the radiation balance is crucial for studying and addressing climate-related issues, which is why ESA, together with the Japan Aerospace Exploration Agency, JAXA, built the EarthCARE satellite.

EarthCARE has been designed to measure various aspects of our atmosphere to help us understand how clouds and aerosols reflect incoming solar energy back out to space and how they trap outgoing infrared energy.

This information is crucial to understand climate change and to predict the rate at which clouds and aerosols could lose their current overall cooling effect in the future.

Remarkably, despite only being launched a little over a month ago, EarthCARE has already returned the first data from its cloud profiling radar.

And now, its broadband radiometer is also demonstrating its impressive capabilities.

ESA’s Director of Earth Observation Programs, Simonetta Cheli, said, “Of course we have never doubted the EarthCARE broadband radiometer’s potential, but here we see, at such an early stage in the mission, that the instrument is working very well and delivering excellent data.

“Each of the satellite’s different instruments has an extremely important role to play—and when all of them are working in harmony and the satellite is commissioned, then the scientific community and weather forecasters will have a powerful tool to advance our understanding of Earth’s energy balance, advance climate science and improve weather predictions.”

Crucial to the mission, the broadband radiometer measures radiative fluxes at the top of Earth’s atmosphere.

As the satellite travels along its orbit, the broadband radiometer is unique in the fact that it views the atmosphere from three directions simultaneously.

This information will allow scientists to accurately measure how much incoming energy from the sun is being reflected back out to space and how much thermal energy is being emitted from Earth’s surface at the same time.

The broadband radiometer’s three different viewing angles—one directly down from the satellite, one in front of the satellite’s path (forward) and one behind the satellite’s path (backward)—are key to capturing systematic three-dimensional views of both reflected and emitted radiation.

Comparing this to the radiation calculated from the combined measurements from the satellite’s other instruments will significantly improve our understanding of aerosol–cloud–radiation interactions.

The image above was taken on 18 July, just a few hours after the broadband radiometer started its measurements. It shows brightness in the forward view along EarthCARE’s orbital path across the western Mediterranean, around a 1,300 km stretch from northern Spain to Algeria.

The brightness indicates how much solar energy is reflected back to space. For example, white bright clouds reflect a lot of sunlight, shown in red, while the sea reflects little sunlight back to the satellite and appears dark, shown in blue.

While the data show a distinct transition between the coast of Spain and the Mediterranean Sea, there is little difference over the open sea. The switch from darker to brighter colors over the Algerian coast is down to the presence of aerosols and thin cloud.

The image below zooms into the Atlas Mountains where thunder clouds tower 10 km into the atmosphere. The broadband radiometer’s three different viewing angles capture the clouds from slightly different positions.

This can be seen in the apparent positions of the cloud’s shadows relative to the clouds: they seem to be north of the cloud for the forward view, east for the down view, and south for the backward view.

This combination of viewing angles is the instrument’s strength—one view only would not fully reveal the sunlight or the thermal radiation being reflected or emitted by cloud and other features. The view from multiple angles gathers information about the directional distribution of the energy that is seen at the top of the atmosphere.

Having this three-dimensional view globally, along with data from EarthCARE’s three other instruments—the cloud profiling radar, the atmospheric lidar and the multispectral imager—is key to advancing climate science.

An international team of researchers from the Universities of Tübingen (Dr. Armando Falcucci), Siena, and Bologna analyzed the cultural remains left by groups of early Homo sapiens at Grotta di Castelcivita in southern Italy, dating back to before the major eruption known as the Campanian Ignimbrite.

This explosive event, originating in the still-active Phlegraean Fields about 40,000 years ago, is considered the most powerful volcanic eruption ever recorded in the Mediterranean. Crucially, Grotta di Castelcivita is one of the rare archaeological sites where volcanic ash has sealed a high-resolution archaeological sequence.

By employing a set of cutting-edge methodologies to meticulously reconstruct the methods used in crafting stone tools—the most enduring artifacts unearthed in prehistoric excavations—the researchers demonstrated that cultural development at Castelcivita predates both the deposition of the volcanic layers and the sub-contemporaneous cold climate phase known as Heinrich Stadial 4, which lasted for about 2 millennia.

The most remarkable cultural innovation recorded at the site is the production of miniaturized stone points from rocks collected near the cave with the most suitable fracture properties. These micro-tools were likely intended to be hafted into multi-component projectile weapons.

This discovery challenges long-held speculations that natural disasters, such as volcanic eruptions and cooling events, were crucial drivers of major changes in the lifeways of hunter-gatherers throughout human prehistory.

The study, published in Scientific Reports, hypothesizes instead that cultural innovations among early Homo sapiens originated from mechanisms of cultural transmission and the establishment of large-scale networks that extended beyond the Alps.

Overall, this research represents a significant step towards understanding how Upper Paleolithic hunter-gatherer societies developed sophisticated strategies to thrive in changing environments.

Grotta di Castelcivita is one of the most important prehistoric deposits in Europe, containing a high-resolution stratigraphic sequence with evidence for the replacement of Neanderthals by early Homo sapiens groups about 43,000 years ago.

Excavations and research at this site are conducted with permission from the Italian Ministry of Culture by the Research Unit of Prehistory and Anthropology, Department of Physical Sciences, Earth, and Environment at the University of Siena, under the direction of Adriana Moroni.

If you scroll through the average student’s digital textbook or reading, you will probably see multi-colored streaks scattered everywhere. However, new research reveals that excessive highlighting may do more harm than good.

Researchers at Waterloo excel at creating new technologies, investigating human-technology interactions, and exploring how to mitigate harm. That’s why it’s no surprise that two computer scientists from Waterloo investigated whether technology controlling the number of words a user can highlight could affect their reading comprehension.

The work earned the duo the Best Paper Award at the Conference on Human Factors in Computing Systems (CHI 2024) one of the top-ranked conferences in computer science and the leading international HCI conference.

The research, “Constrained Highlighting in a Document Reader Can Improve Reading Comprehension,” was published in the Proceedings of the CHI Conference on Human Factors in Computing Systems.

“There are lots of theories in psychology that show having constraints is really beneficial, especially for encouraging creativity,” says Nikhita Joshi (MMath ’20), a Ph.D. student specializing in human-computer interaction (HCI) research at the David R. Cheriton School of Computer Science.

“Traditionally, software constraints were mainly used for error-proofing. However, my research focuses on using constraints to influence positive outcomes for users, which I call ‘bounded interactions.'”

These theories inspired Joshi and her supervisor Dr. Daniel Vogel to recruit 127 participants to read a short story. After 24 hours, they completed a reading comprehension test, answering 20 multiple-choice questions within five minutes. The participants were divided into three groups: no highlights, limited highlights of 150 words and unlimited highlights.

The duo chose this restraint after running a similar experiment where participants were assigned different conditions such as 50 words, 150 words and 250 words. The group capped at 150 words had the highest test results, leading to promising research directions.

For this study, Joshi designed a web-based document reader using React JS in JavaScript, which hosted the reading and test interfaces. This tool can notify how many words a user highlights and if they are exceeding the limit.

Notably, the group with limited highlights scored the highest on the reading comprehension test, with scores 11% higher than the unlimited highlights, and 19% higher than the no highlights groups. This difference is equivalent to one to two letter grades. There were also no noticeable differences in each group’s reading time, showing that highlighting restraints does not impede a user’s mental demand, effort or frustration.

This research was the first to prove that restricted highlighting can boost reading comprehension. It is also the first to explore user interface constraints for text marking. Excessive highlighting has been a long-standing problem in pedagogy. Although many researchers have proposed solutions such as in-person self-regulation training, it can be time-consuming and strenuous. As a result, this innovative technology may be a faster and easier solution for better study habits.

In a follow-up questionnaire, most of the participants stated that the cap prompted them to concentrate on the most important parts of the story. Their highlights were shorter and focused on keywords like nouns, which are strategies recommended by some university learning centers.

What surprised the researchers the most was that some participants were reluctant to delete highlights despite having the option. Instead, they were more mindful, adopting different tactics like “highlighting a noun at the beginning of the sentence and using this as a bookmark to refer to later in the document,” Joshi shares.

This research comes at a time when literacy scores are declining across the globe. “There are concerns that the development of students’ cognitive skills may be declining, especially with the development of tools like ChatGPT,” Joshi says. “Reading is core to other cognitive skills like self-reflection, self-regulation, and critical thinking. All of that is super important to human intelligence.”

In the future, the group may launch a prototype of their current work. Joshi also wants to conduct a similar experiment but with non-fiction documents like academic papers or news articles. However, she would investigate and impose a different condition since 150 words may be too restrictive for long and complex reading.

One idea is to have a limit relative to the document structure. “Instead of having this one encompassing limit for the entire research paper, we would split the limit into different sections,” she says. “Perhaps the related work section can have a lower highlight limit, but the result sections could be higher since that’s the most important part of the paper.”

NASA is preparing for a new mission, dubbed Landolt Space Mission, by the end of the decade, that will place a satellite which will function just like an artificial star. The main objective of the mission is to improve the precision of ground-based telescopes, increasing our knowledge of the Universe. The satellite will launch in early 2029 and will be about the size of a loaf of bread. 

The lab will house eight lasers that will provide everything from the light of stars to that of a supernova. This satellite will function as a new calibration technique for astronomers to fine-tune their telescopes and other instruments in observatories. This will enable them to take more accurate measurements of real celestial objects.

The artificial star satellite will be placed 35,785 kilometres above Earth. This distance will allow it to sit in a geosynchronous orbit, which will be stationary when viewed from the Earth. According to a newsroom post by George Mason University, the principal investigator for the mission, Peter Plavchan said that the distance is intended to make the satellite appear like a real star. Further, the geosynchronous positioning will keep placed over the US in the first year, enabling better observation by NASA and other independent observatories in the country.

The artificial star will be invisible to the naked eye but will be easily detectable by typical telescopes that use digital cameras to capture images. If adopted, such a setup could help astronomers hone in on changes in stellar luminosity and related attributes with increased precision. Named after Arlo Landolt, a key player in creating stellar brightness catalogs, the mission was approved by NASA in February and disclosed to the public on June 10. The effort, the company says, would require 30 people and have an approximate price tag of $19,500,000 (roughly Rs. 162.8 crore).

The Landolt Space Mission is a breakthrough in space exploration. As a more constant and well-known sky ‘landmark’ it will allow scientists to better calibrate their methods and secure more exact data with every observation — effectively revealing more of the mystery of the cosmos.

After the Romans conquered Britain in AD 43, the technologies and laws they introduced led to centuries of economic growth of a kind once thought to be limited to modern industrial societies. That is the conclusion of an analysis of thousands of archaeological finds from this time.

“Over that period of about 350 years, you’re looking at roughly a two and a half [fold] increase in productivity per capita,” says Rob Wiseman at the University of Cambridge.

It has long been believed that economic growth in the ancient world depended on having more people and more resources, says Wiseman: to increase food production, say, required more land and more farm workers. This kind of growth is known as extensive growth.

By contrast, economic growth today is driven mainly by increased productivity, or intensive growth. Thanks to mechanisation and better breeds of plants and animals, for instance, more food can be produced from the same area of land with fewer workers.

Some recent studies have challenged the idea that intensive growth occurred only after the industrial age began, inspiring Wiseman and his colleagues to look at growth in Roman Britain from AD 43 to 400.

The team’s research was made possible by UK laws requiring archaeological investigations to be done when a site is developed, says Wiseman. “The result is there’s been tens of thousands of archaeological excavations done in this country. And, moreover, that data is publicly accessible.”

By looking at how the number of buildings changed over time, the researchers were able to get an idea of how the population of Roman Britain grew. There is a strong relation between the number of buildings and population size, says Wiseman.

To get an idea of economic growth, the team looked at three measures. One was the size of buildings, rather than the number of them. As people grow richer, they build bigger houses, says Wiseman.

Another measure was the number of lost coins found in digs. “These are things that have fallen through the floorboards, or they’ve been lost in the baths, or something like that,” he says.

The idea is that the more coins are in circulation, the more are likely to be lost. The team didn’t count hidden hoards of coins, as these reflect instability rather than growth.

The third measure was the proportion of crude pottery, such as cooking pots and storage pots, to more ornate pottery like decorated plates. Economic growth requires people to interact more and socialise more, which means “showing off” when guests are present, says Wiseman.

Based on these measures, the team found that economic growth exceeded that expected from population growth alone. They estimate that per capita growth was around 0.5 per cent between AD 150 and 250, slowing to around 0.3 per cent between AD 250 and 400.

“What we’re able to show is yes, after the Romans arrived, there was definitely intensive growth,” says Wiseman. The pace of growth rather than the kind of growth is what probably distinguishes the modern world from the ancient one, he says.

The researchers think that this growth was driven by factors such as the roads and ports built by the Romans, the laws they introduced making trading safer, and their technologies, such as more advanced grain mills and better breeds of animals for ploughing.

The higher growth between AD 150 and 250 may be a result of Britain catching up with the rest of the Roman world, says Wiseman. “You’re moving from a small tribal society where there’s not a lot of interaction going on to a world-spanning economy.”

What isn’t clear is whether this economic development made people happier or healthier. “Just because the productivity is going up doesn’t automatically mean that the welfare of Britons who were invaded and colonised was better under Rome,” says Wiseman. “That’s an open question.”

To investigate this, the researchers now plan to look at human remains to work out things such as how long people lived.

“I am convinced that they are right and that, indeed, intensive growth took place in Roman Britain,” says Alain Bresson at the University of Chicago, Illinois.

“A lot of archaeologists have noted compelling evidence for economic growth in Roman Britain, but this paper adds a welcome formal theoretical dimension to the discussion,” says Ian Morris at Stanford University, California.

However, Morris suspects that the lower average growth rate from AD 250 to 400 actually reflects high growth followed by rapid decline as the Roman empire began to break up. Further studies will resolve this, he says.

A new catalyst may well catalyze a shift to greener chemistry. Chemists from Yokohama National University have successfully developed innovative catalysts containing two noble metals that demonstrate remarkable efficiency in ester-producing chemical reactions and utilize oxygen as the sole oxidant, making the process much more environmentally friendly and sustainable.

Their results were published in the Journal of the American Chemical Society on June 6.

Cross-Dehydrogenative Coupling (CDC) reactions belong to the category of C−H bond activation reactions, which play a crucial role in organic synthesis and industrial chemistry. CDC reactions have been extensively developed as sustainable chemical synthesis strategies owing to their atom economy, meaning they use reactants efficiently and minimize waste.

CDC reactions between arenes and carboxylic acids activate the C–H bond of arenes (aromatic hydrocarbons such as benzene) to form C–O bonds with carboxylic acids to directly produce aryl esters. Esters are chemical compounds widely used in various industries, including pharmaceuticals and polymer production.

These CDC reactions, however, require oxidants, or oxidizing agents, to occur.

“Cross-dehydrogenative coupling reactions of arenes and carboxylic acids have typically been conducted by homogeneous catalysts with hazardous oxidants such as hypervalent iodine reagents,” said Ken Motokura, a professor at the Faculty of Engineering of Yokohama National University and corresponding author of the study.

Traditional oxidants can be highly toxic to humans and animals, cause explosions, or produce pollution or harmful byproducts. These methods, therefore, pose significant environmental and safety concerns.

Seeking a greener approach, the research team developed catalysts called RhRu bimetallic oxide clusters (RhRuO_x/C), which are composed of two metals from the noble metals group, Rhodium (Rh) and Ruthenium (Ru), combined with oxygen.

With a mean diameter of just 1.2 nm, these catalysts demonstrated exceptional catalytic activity in CDC reactions while utilizing oxygen as the sole oxidant. Molecular oxygen is non-toxic, abundant, environmentally benign and highly efficient in converting reactants to products, with water being the only byproduct.

Using advanced imaging and spectroscopic techniques, the researchers confirmed the structure and formation of the RhRu bimetallic oxide clusters. Detailed kinetic and computational studies revealed the reaction mechanism. The catalysts’ high reactivity with various types of arenes and carboxylic acids was demonstrated, making them versatile for producing aryl esters.

“Our study shows that noble-metal-based bimetallic oxide clusters are promising for the C–H bond activation reactions using molecular oxygen as the sole oxidant,” said Shingo Hasegawa, an assistant professor at the Faculty of Engineering of Yokohama National University and first author of the study.

The new catalysts show potential for making chemical reactions more sustainable and efficient, opening up possibilities for greener chemical synthesis. The researchers plan to explore the use of these catalysts in other important chemical reactions.

“Our ultimate goal is to establish efficient and regioselective C–H functionalization reactions catalyzed by metal oxide clusters using molecular oxygen under mild conditions, promoting more environmentally friendly chemistry practices,” Motokura said.