Adnan Rajib, a UT Arlington assistant professor in the Department of Civil Engineering, was the lead author on the published study, “Human Alterations of the Global Floodplains.”His doctoral student, Qianjin Zheng, played a significant role in developing the research.

U.S. Environmental Protection Agency (EPA) scientists Charles Lane, Heather Golden and Jay Christensen; Itohaosa Isibor of Texas A&M University-Kingsville; and Kris Johnson of The Nature Conservancy collaborated on the study. The work was funded through NASA and the National Science Foundation.

“The bottom line is that the world is at greater flood risk than what we realized, especially considering what effect human development has had on floodplains,” Rajib said. “In 27 years, between 1992 and 2019, the world has lost a dramatic 600,000 square kilometers of floodplains due to human disturbances, which include infrastructure development, industry and business construction and expansion of agriculture.”

The team used satellite remote sensing data and geospatial analytics in studying 520 major river basins of the world, discovering previously unknown spatial patterns and trends of human floodplain alterations.

“Mapping the world’s floodplains is relatively new. While there is increasing awareness to map floodplains accurately and understand flood risks, an attempt to map human disturbances in those floodplains at a global scale never existed,” said Rajib, who also is the director of the UT Arlington Hydrology and Hydroinformatics Innovation Lab. “It’s been done in smaller regions around the world and certainly in the United States and Europe, but not in data-poor regions of the world.”

The study concludes that wetland habitats are in danger and that one-third of the total global loss of floodplain wetlands occurred in North America. Rajib said the magnitude of risk for floodplains is much larger than what was previously understood. He and the team examined satellite pictures of those floodplain areas taken over the past 27 years.

“We wanted to look at floodplains at the neighborhood level,” Zheng said. “We wanted to see the impact of development on someone who lives adjacent to or near a floodplain. Some of the changes in these pictures are good, like when trees are planted or parks are built. But many of the pictures reveal disturbing outcomes. For instance, we saw a dramatic increase in the development of parking lots or the construction of buildings without adequate stormwater runoff allowances.”

Johnson, a co-author on the paper, said that “worldwide, floodplains are biodiversity hotspots that also provide a wide range of ecosystem services for people. We hope this study sheds light on this critical habitat we’re losing as well as ways in which we can reverse the trend.”

Melanie Sattler, chair and professor of the Department of Civil Engineering, said this study should give planners a vital tool to reduce flood risks for people.

“Rajib’s work can be our lens to help guide future development in order to decrease susceptibility to floods in a changing climate,” Sattler said. “And, in some cases, we hope this study can help us correct mistakes we’ve made through past development decisions.”

That belief is reflected in his team’s new publication in the journal Advanced Sustainable Systems.

Rabnawaz and his colleagues showed that sodium chloride — table salt — can outperform much more expensive materials being explored to help recycle plastics.

“This is really exciting,” Rabnawaz said. “We need simple, low-cost solutions to take on a big problem like plastics recycling.”

Although plastics have historically been marketed as recyclable, the reality is that nearly 90% of plastic waste in the United States ends up in landfills, in incinerators or as pollution in the environment.

One of the reasons plastics have become so disposable is that the materials recovered from recycling aren’t valuable enough to spend the money and resources required to get them.

According to the team’s projections, table salt could flip the economics and drastically reduce costs when it comes to a recycling process known as pyrolysis, which works through a combination of heat and chemistry.

Although Rabnawaz expected salt to have an impact because of how well it conducts heat, he was still surprised by how well it worked. It outperformed expensive catalysts — chemicals designed to spur reactions along — and he believes his team has just started tapping into its potential.

Furthermore, the work is already getting attention from big names in industry, he said.

In fact, the research was partially supported by Conagra Brands, a consumer packaged goods company. The U.S. Department of Agriculture and MSU AgBioResearch also helped finance the work.

A catalyst worth its salt

Pyrolysis is a process that breaks down the plastics into a mixture of simpler, carbon-based compounds, which come out in three forms: gas, liquid oil and solid wax.

That wax component is often undesirable, Rabnawaz said, yet it can account for more than half of products, by weight, of current pyrolysis methods. That’s even when using catalysts, which are helpful, but they often can be toxic or prohibitively expensive to be applied in managing waste plastics.

Platinum, for example, has very attractive catalytic properties, which is why it’s used in catalytic converters to reduce harmful emissions from cars. But it’s also very pricey, which is why thieves steal catalytic converters.

Although bandits are unlikely to rob platinum-based materials from a sweltering pyrolysis reactor, attempting to recycle plastics with those catalysts would still require a hefty investment — millions, if not hundreds of millions, of dollars, Rabnawaz said. And current catalysts aren’t efficient enough to justify that cost.

“No company in the world has that kind of cash to burn,” Rabnawaz said.

In earlier work, Rabnawaz and his team showed that copper oxide and table salt worked as catalysts to break down a plastic known as polystyrene. Now, they’ve shown table salt alone can eliminate the wax byproduct in the pyrolysis of polyolefins — polymers that account for 60% of plastic waste.

“That first paper was important, but I didn’t get excited until we worked with polyolefins,” Rabnawaz said. “Polyolefins are huge, and we just outperformed expensive catalysts.”

Joining Rabnawaz on this project were Christopher Saffron, an associate professor in the College of Agriculture and Natural Resources, visiting scholar Mohamed Shaker and MSU doctoral student Vikash Kumar.

When using table salt as a catalyst to pyrolyze polyolefins, the team produced mostly liquid oil containing hydrocarbon molecules similar to what’s found in diesel fuel, Rabnawaz said. Another perk of the salt catalyst, the researchers showed, is it can be reused.

“You can recover salt by simply washing the obtained oil with water,” Rabnawaz said.

The researchers also showed that table salt aided in the pyrolysis of metallized plastic films, which are commonly used in food packaging, like potato chip bags, which isn’t currently recycled.

Although pure table salt didn’t outperform a platinum-alumina catalyst the team also tested with metallized films, the results were similar, and the salt is a fraction of the cost.

Rabnawaz, however, stressed that metallized films, while useful, are inherently problematic. He envisions a world where such films are no longer needed, which is why his team is also working to replace them with more sustainable materials.

The team will also continue working to further its pyrolysis project.

For instance, the team has yet to fully characterize the gas products of pyrolysis with table salt. And Rabnawaz believes the team can improve this approach so that the liquid products contain chemicals with more valuable applications than being burned as fuel.

Still, the early returns of the team’s new table salt tactics are encouraging. Based on a quick, preliminary economic analysis, the team estimated a commercial pyrolysis reactor could triple its profits just by adding salt.

Cold Spring Harbor Laboratory (CSHL) Professor Christopher Hammell has found that in the worm C. elegans, this genetic orchestra has no single conductor. Instead, a quartet of molecules works in concert to time each developmental stage. Hammell says this process shares some similarities with the circadian clocks that control human behavior. Understanding how the worm’s clock is regulated could help explain how time affects development in other animals. Hammell explains:

“This clock we’ve discovered sets the cadence of development. It’s a coordinator of the orchestra. It controls when the trombone goes, how loud it gets, and how long the note lasts.”

Each stage of C. elegans‘ development begins with two proteins, NHR-85 and NHR-23. They work together to spark a pulse of gene expression, switching on the microRNA lin-4, which controls stem cell development patterns. The pulse’s timing, strength, and duration depend on the short stretch when NHR-85 and NHR-23 interact, and another protein, LIN-42, which ends each developmental period by shutting off NHR-85.

“Mess up the orchestra — it’ll still make sound,” Hammell says. “But the way the music changes lets us know proper timing is critical for development.”

Hammell teamed with Wolfgang Keil from Paris’ Curie Institute to observe this gene expression cycle in action. C. elegans takes about 50 hours to reach adulthood. During that time, it’s always on the move, like a restless teenager. The team developed a new imaging technique to hold the tiny worm in place long enough to take pictures and video. This let them measure each developmental beat as it occurred.

“We could see every time genes turned on from birth to adulthood,” Hammell says. “This kind of imaging had never been done in animals, only in single cells.”

Hammell is now working with CSHL Professor & HHMI Investigator Leemor Joshua-Tor to image how clock proteins interact over time.

“We want to work out, with even more precision, how this clock operates,” Hammell says. “Humans can do things like write music or perform calculus, not because we have a calculus or music gene, but because our developmental clocks enable our brain to develop longer into a more complex organ.”

In other words, when it comes to development, time is truly of the essence.

“In our earlier work, we demonstrated that our soft robot was able to twist and turn its way through a very simple obstacle course,” says Jie Yin, co-corresponding author of a paper on the work and an associate professor of mechanical and aerospace engineering at North Carolina State University. “However, it was unable to turn unless it encountered an obstacle. In practical terms this meant that the robot could sometimes get stuck, bouncing back and forth between parallel obstacles.

“We’ve developed a new soft robot that is capable of turning on its own, allowing it to make its way through twisty mazes, even negotiating its way around moving obstacles. And it’s all done using physical intelligence, rather than being guided by a computer.”

Physical intelligence refers to dynamic objects — like soft robots — whose behavior is governed by their structural design and the materials they are made of, rather than being directed by a computer or human intervention.

As with the earlier version, the new soft robots are made of ribbon-like liquid crystal elastomers. When the robots are placed on a surface that is at least 55 degrees Celsius (131 degrees Fahrenheit), which is hotter than the ambient air, the portion of the ribbon touching the surface contracts, while the portion of the ribbon exposed to the air does not. This induces a rolling motion; the warmer the surface, the faster the robot rolls.

However, while the previous version of the soft robot had a symmetrical design, the new robot has two distinct halves. One half of the robot is shaped like a twisted ribbon that extends in a straight line, while the other half is shaped like a more tightly twisted ribbon that also twists around itself like a spiral staircase.

This asymmetrical design means that one end of the robot exerts more force on the ground than the other end. Think of a plastic cup that has a mouth wider than its base. If you roll it across the table, it doesn’t roll in a straight line — it makes an arc as it travels across the table. That’s due to its asymmetrical shape.

“The concept behind our new robot is fairly simple: because of its asymmetrical design, it turns without having to come into contact with an object,” says Yao Zhao, first author of the paper and a postdoctoral researcher at NC State. “So, while it still changes directions when it does come into contact with an object — allowing it to navigate mazes — it cannot get stuck between parallel objects. Instead, its ability to move in arcs allows it to essentially wiggle its way free.”

The researchers demonstrated the ability of the asymmetrical soft robot design to navigate more complex mazes — including mazes with moving walls — and fit through spaces narrower than its body size. The researchers tested the new robot design on both a metal surface and in sand.

“This work is another step forward in helping us develop innovative approaches to soft robot design — particularly for applications where soft robots would be able to harvest heat energy from their environment,” Yin says.

The work was done with support from the National Science Foundation under grants 2005374, 2126072, 1944655 and 2026622.

Synchronised phenomena are all around us, whether it is human clapping and dancing, or the way fireflies flash, or how our neurons and heart cells interact. However, it is something not fully understood in engineering and science.

Associate Professor Joseph Lizier, expert in complex systems at the University of Sydney, said: “We know the feeling of dancing in step to the ‘Nutbush’ in a crowd — or the awkward feeling when people lose time clapping to music. Similar processes occur in nature, and it is vital that we better understand how falling in and out of sync actually works.

“Being in sync in a system can be very good; you want your heart cells to all beat together rather than fibrillate. But being in sync can also be very bad; you don’t want your brain cells to all fire together in an epileptic seizure.”

Associate Professor Lizier and colleagues at the Max Planck Institute in Leipzig, Germany have published new research on synchronisation in the Proceedings of the National Academy of Sciences (PNAS).

The paper sets out the mathematics of how the network structure connecting a set of individual elements controls how well they can synchronise their activity. It is a critical insight into how these systems operate, because in most real-world systems, no one individual element controls all the others. And nor can any individual directly see and react to all the others: they are only connected through a network.

Associate Professor Lizier, from the Centre of Complex Systems and the School of Computer Science in the Faculty of Engineering, said: “Our results open new opportunities for designing network structures or interventions in networks. This could be super useful in stabilising electricity in power grids, vital for the transition to renewables, or to avoid neural synchronisation in the brain, which can trigger epilepsy.”

To understand how these systems work, the researchers studied what are known as “walks” through a network in a complex system. Walks are sequences of connected hops between individual elements or nodes in the network.

Associate Professor Lizier said: “Our maths examines paired walks: where you start at one node and set off on two walks with randomly chosen hops between nodes for a specified number of steps. Those two walks might end up at the same node (convergent walks) or at different nodes (divergent walks).

“Our main finding is that the more commonly paired walks on a network are convergent, the worse the quality of synchronisation on that network structure would be.”

This is good news for the brain, where synchronisation is not desirable as it can cause epilepsy . The brain’s highly modular structure means it has a high proportion of convergent walks, which naturally push it away from epilepsy.

“We can even draw an analogy to social media with the echochamber phenomenon,” said co-author Jürgen Jost, whose group also works on social network dynamics. “Here we see sub-groups reinforcing their own messages, via convergent walks within their own group, but not necessarily synchronising to the wider population.”

The findings represent a major step forward in the theory of how the structure of complex networks affects their dynamics or how they compute, such as how brain structure underpins cognition.

The research was supported by the Australian Research Council Discovery Early Career Researcher Award (DECRA) grant DE160100630, the The University of Sydney, Sydney Research Accelerator (SOAR) award, the Alexander von Humboldt Foundation and the NSF Grant Division of Mathematical Sciences (DMS)-0804454 Differential Equations in Geometry. The research used the University of Sydney’s high-performance computing cluster Artemis in generating the paper’s results for this paper.

The researchers declare no competing interests.

Bio-oils resulting from the intense heating (pyrolysis) of industrial or agricultural by-products, are increasingly seen as potential alternatives to fossil fuels. But the stability and consequent treatment of these bio-oils depends entirely on their composition; and since they are often mixtures of many dozens, or hundreds, of different compounds, analysing such complex mixtures is not simple — or cheap.

Dr Robert Evans, Senior Lecturer in Physical Chemistry at Aston University, explains: “The composition of any pyrolysis bio-oil is absolutely key to future use. For example if there are oxygen-containing chemicals in the oil, that will make the oil more corrosive and it will be more unstable. So in particular we need to know if carbonyl groups are present — where oxygen and carbon atoms are bonded together — as these can have a major impact.”

A leading method of analysis is high-field nuclear magnetic resonance (NMR) spectroscopy, which gives a detailed breakdown of the identity and concentration of chemical species present in any sample. However these large high-field NMR spectrometry machines cost in the range of £600,000-£10million and require a supply of expensive cryogens and solvents, so are generally only found in the very biggest research facilities.

The team at Aston, led by Dr Evans, set out to see if ‘low-field’, or benchtop, NMR spectrometers, could analyse pyrolysis oils well enough to produce the necessary detailed information. Benchtop NMR spectrometers use permanent magnets, which don’t require cryogenic cooling, so cost much less to purchase and maintain. However, using lower strength magnets comes at the cost of lower sensitivity and poorer resolution. While they can find some use as research instruments, they are also commonly found in teaching laboratories.

The study, carried out with collaborators at the University of Tennessee, tested pyrolysis oils produced from a number of different plants, and compared the results from benchtop spectrometers to both high-field spectrometers and other methods of analysis. They found that the benchtop machine estimates compared favourably with titration analysis for overall carbonyl content, as well as matching high-field spectrometry for the specific identification of carbonyl groups such as ketones, aldehydes and quinones.

Dr Evans said: “Despite the known limitations of benchtop spectrometers, a very similar quality of NMR data could be obtained for these samples, enough to accurately estimate concentrations of different classes of carbonyl-containing species. Using benchtop spectrometers will make NMR analysis of pyrolysis oils much simpler, cheaper, and more accessible to a wider range of different users.”

Specifically, the finding took place during a research stay of the expert Stefano Torniamenti at the ICCUB, one of the research units that make up the IEEC.

Black holes in the Hyades star cluster?

Since their discovery, black holes have been one of the most mysterious and fascinating phenomena in the Universe and have become the object of study for researchers all over the world. This is particularly true for small black holes because they have been observed during the detection of gravitational waves. Since the detection of the first gravitational waves in 2015, experts have observed many events that correspond to mergers of low-mass black hole pairs.

For the published study, the team of astrophysicists used simulations that track the motion and evolution of all the stars in the Hyades — located at a distance from the Sun of about 45 parsecs or 150 light-years — to reproduce their current state.

Open clusters are loosely bound groups of hundreds of stars that share certain properties such as age and chemical characteristics. The simulation results were compared with the actual positions and velocities of the stars in the Hyades, which are now known precisely from observations made by the European Space Agency’s (ESA) Gaia satellite.

“Our simulations can only simultaneously match the mass and size of the Hyades if some black holes are present at the centre of the cluster today (or until recently),” says Stefano Torniamenti, postdoctoral researcher at the University of Padua and first author of the paper.

The observed properties of the Hyades are best reproduced by simulations with two or three black holes at present, although simulations where all the black holes have been ejected (less than 150 million years ago, roughly the last quarter of the cluster’s age) can still give a good match, because the evolution of the cluster could not erase the traces of its previous black hole population.

The new results indicate that the Hyades-born black holes are still inside the cluster, or very close to the cluster. This makes them the closest black holes to the Sun, much closer than the previous candidate (namely the black hole Gaia BH1, which is 480 parsecs from the Sun).

In recent years, the breakthrough of the Gaia space telescope has made it possible for the first time to study the position and velocity of open cluster stars in detail and to identify individual stars with confidence.

“This observation helps us understand how the presence of black holes affects the evolution of star clusters and how star clusters in turn contribute to gravitational wave sources,” says Mark Gieles, a member of the UB Department of Quantum Physics and Astrophysics and host of the first author in Barcelona. “These results also give us insight into how these mysterious objects are distributed across the galaxy.”

The new study is the result of close collaboration between the University of Padova, ICUBB-IEEC, the University of Cambridge (United Kingdome), the European Southern Observatory (ESO) and the National Sun Yat-sen University (China).

The study, conducted using a commercial process simulator, unveils significant findings regarding the efficiency and economic viability of utilizing ammonia in power generation systems. Results indicate an impressive energy efficiency rate of 46.7% within the designed power generation process.

Through comprehensive economic analysis, the research team identified an upper limit for ammonia pricing at 421.3 $ tNH3-1 that allows competitive pricing against industrial electricity rates — a crucial factor in determining market competitiveness.

To further optimize ammonia imports into the Republic of Korea (KOR), five distinct scenarios were established based on historical data from the top ten exporting countries. Using the Monte Carlo method for ammonia production costs and carbon dioxide emissions in each nation, researchers optimized import quantities while minimizing overall emissions.

The results demonstrate that if solely reliant on carbon-based ammonia imports, carbon intensity ranges between 0.707-0.736 kgCO2-eq kWh−1 — exceeding KOR’s average value over a 20-year period. However, achieving a ratio of over 78% of carbon-neutral ammonia (Scenario 4) can make both environmental and economic aspects more favorable.

According to the research team, their findings provide valuable insights into optimizing ammonia exports and reducing carbon intensity. By adopting a holistic approach that encompasses all stages of the supply chain, significant progress can be made towards sustainable energy solutions.

“Our study sheds light on the immense potential of ammonia as an energy source,” said Professor Lim. “We have analyzed costs and greenhouse gas emissions while considering different commercialized methods of producing ammonia. Although renewable energy sources were not part of this particular study, our findings offer crucial insights into enhancing ammonia exports and promoting sustainability.”

The study findings have been published ahead of their official publication in the online version of Chem. Eng. J. on May 13, 2023. This work has been supported by the National Research Foundation of Korea (NRF), the Carbon Neutrality Demonstration and Research Center of UNIST, the Ministry of Trade, Industry and Energy and Korea (MOTIE), and Korea Evaluation Institute of Industrial Technology (KEIT). Their findings are expected to contribute to advancing the understanding and utilization of ammonia as a viable option for decentralized power generation systems.

A research team comprising the UK Centre for Ecology & Hydrology (UKCEH) and the Universities of Birmingham, Reading, Surrey and Southern Queensland, found that ozone substantially changes the size and scent of floral odour plumes given off by flowers, and that it reduced honeybees’ ability to recognise odours by up to 90% from just a few metres away.

Ground-level ozone typically forms when nitrogen oxide emissions from vehicles and industrial processes react with volatile organic compounds emitted from vegetation in the presence of sunlight.

Professor Christian Pfrang from the University of Birmingham who collaborated on the research said: “Our study provides robust evidence that the changes due to ground-level ozone on floral scent cause pollinators to struggle to carry out their crucial role in the natural environment also with implications for food security.”

The findings suggest that ozone is likely to be having a negative impact on wildflower abundance and crop yields. International research has already established that ozone has a negative impact on food production because it damages plant growth.

Dr Ben Langford, an atmospheric scientist at UKCEH who led the study said: “Some 75% of our food crops and nearly 90% of wild flowering plants depend, to some extent, upon animal pollination, particularly by insects. Therefore, understanding what adversely affects pollination, and how, is essential to helping us preserve the critical services that we reply upon for production of food, textiles, biofuels and medicines, for example.”

The researchers used a 30-m wind tunnel at Surrey University to monitor how the size and shape of odour plumes changed in the presence of ozone. As well as decreasing the size of the odour plume the scientists found that the scent of the plume changed substantially as certain compounds reacted away much faster than others.

Honeybees were trained to recognise the same odour blend and then exposed to the new, ozone-modified odours. Pollinating insects use floral odours to find flowers and learn to associate their unique blend of chemical compounds with the amount of nectar it provides, allowing them to locate the same species in the future.

The research showed that towards the centre of plumes, 52% of honeybees recognised an odour at 6 metres, decreasing to 38% at 12 m. At the edge of plumes, which degraded more quickly, 32% of honeybees recognised a flower from 6 m away and just a tenth of the insects from 12 m away.

The study indicates that ozone could also affect insects’ other odour-controlled behaviours such attracting a mate.

The research was funded by the Natural Environment Research Council, part of UK Research and Innovation, and was published in the journal Environmental Pollution.

Professor Christian Pfrang concluded: “We know that air pollution has a detrimental effect on human health, biodiversity and the climate, but now we can see how it prevents bees and other pollinating insects from carrying out their key job. This should act as a wake up call to take action on air pollution and help safeguard food production and biodiversity for the future.”