A team from the Artie McFerrin Department of Chemical Engineering at Texas A&M University consisting of Dr. Abdoulaye Djire, assistant professor, and graduate student Denis Johnson, has furthered a method to produce ammonia through electrochemical processes, helping to reduce carbon emissions. This research aims to replace the Haber-Bosch thermochemical process with an electrochemical process that is more sustainable and safer for the environment.

The researchers recently published their findings in Nature Scientific Reports.

Since the early 1900s, the Haber-Bosch process has been used to produce ammonia. This process works by reacting atmospheric nitrogen with hydrogen gas. A downside of the Haber-Bosch process is that it requires high pressure and high temperature, leaving a large energy footprint. The method also requires hydrogen feedstock, which is derived from nonrenewable resources. It is not sustainable and has negative implications on the environment, expediting the need for new and environmentally friendly processes.

The researchers have proposed using the electrochemical nitrogen reduction reaction (NRR) to produce ammonia from atmospheric nitrogen and water. The benefits of using an electrochemical method include using water to provide protons and the ability to produce ammonia at ambient temperature and pressure. This process would potentially require lower amounts of energy and would be less costly and more environmentally friendly than the Haber-Bosch process.

The NRR works by using an electrocatalyst. For this process to succeed, nitrogen must bond to the surface and break apart to produce ammonia. In this study, the researchers used MXene, a titanium nitride, as the electrocatalyst. What differentiates this catalyst from others is that nitrogen is already in its structure, allowing for more efficient ammonia formulation.

“It’s easier for ammonia to form because the protons can attach to the nitrogen in the structure, form the ammonia and then the ammonia will leave out of the structure,” said Johnson. “A hole is made in the structure that can pull the nitrogen gas in and separate the triple bond.”

The researchers found that using titanium nitride induces a Mars-van Krevelen mechanism, a popular mechanism for hydrocarbon oxidation. This mechanism follows a lower energy pathway that would allow for higher ammonia production rates and selectivity because of the nitrogen from the titanium nitride catalyst.

Without modifications to the materials, the researchers reached a selectivity of 20%, which is the ratio of the desired product formed compared to the undesired product formed. Their method could potentially reach a higher selectivity percentage with modifications, forging a new pathway to ammonia production through electrochemical processes.

“The Department of Energy has set a goal of a selectivity of 60%, which is a challenging number to reach,” said Johnson. “We were able to reach 20% using our material, showcasing a method that we might be able to take advantage of moving forward. If we upgrade our material, can we reach 60% soon? That is the question we will continue to work to answer.”

This research could potentially reduce the carbon footprint and global energy usage on a larger scale.

“In the future, this could be a major scientific reform,” said Djire. “About 2% of the world’s total energy is used for ammonia production. Reducing that huge number would drastically reduce our carbon footprint and energy consumption.”

This study was funded by the Startup Research Fund. Other contributors to the publication are Eric Kelley from the chemical engineering department at Texas A&M, Brock Hunter from Auburn University, and Jevaun Christie and Cullan King from Prairie View A&M University.

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Materials provided by Texas A&M University. Original written by Michelle Revels. Note: Content may be edited for style and length.

The lowland rainforests of the Amazon River basin harbor more diversity than any other terrestrial ecosystem on the planet. It is also a globally important biome containing about 18 percent of all trees on Earth and carrying more fresh water than the next seven largest river basins combined. Researchers have long wondered and hotly debate how the Amazon’s rich biodiversity arose and accumulated.

“Early evolutionary biologists like Alfred Russel Wallace noticed that many species of primates and birds differ across opposite riverbanks in the Amazon, and ornithologists now know that rivers are associated — in one way or another — with the origin of many avian species,” said the study’s lead author Lukas Musher, a postdoctoral researcher at the Academy of Natural Sciences of Drexel University and a recent comparative biology Ph.D. graduate of the American Museum of Natural History’s Richard Gilder Graduate School. “Moreover, accumulating geological evidence has suggested that these rivers are highly dynamic, moving around the South American landscape over relatively short time periods, on the order of thousands or tens of thousands of years.”

To investigate how the movement of rivers across the landscape has influenced the accumulation of bird species in the Amazon, the researchers sequenced the genomes of six species of Amazonian birds.

“Even though birds can fly, our study confirmed that current rivers across the Southern Amazon rainforest, even relatively small ones, are highly effective at isolating populations of these six species, which leads to genomic divergence and ultimately speciation,” said the study’s senior author Joel Cracraft, Lamont Curator and curator-in-charge in the Museum’s Department of Ornithology.

However, because these rivers move around the landscape at different time scales, their movements can have varying outcomes for bird species: when river rearrangements occur quickly, populations of birds on each side can merge before they’ve had time to differentiate; when river changes happen slowly, species have a longer time to diverge from one another; and when rivers change at intermediate rates, bird populations diverge and then join back together and co-occur when a river moves.

The scientists also identified distinct populations of birds that should be described as separate species but have been considered a single species until now.

“Though we know Amazonian biodiversity is unmatched by any other terrestrial ecosystem, we demonstrated that its species richness may be greatly underestimated even in well-studied groups such as birds,” Musher said. “Our results corroborate those of other studies that have reported fine-scale patterns of diversity across the southern Amazon basin — a region threatened by rapid and ongoing deforestation — yet this diversity is generally unrecognized. Many of the distinct populations are relatively young and endemic to a small Amazonian region, meaning that a large portion of the Amazon’s birds may be threatened with loss to imminent extinction.”

Other authors on this study include Melina Giakoumis, City College of New York; James Albert, University of Louisiana at Lafayette; Glaucia Del-Rio, Marco Rego and Robb T. Brumfield, Louisiana State University; Camila C. Ribas, Instituto Nacional de Pesquisas da Amazônia; Alexandre Aleixo, University of Helsinki, Museu Paraense Emílio Goeldi, and Instituto Tecnológico Vale, Belém, Brazil; and Gregory Thom and Brian Smith, American Museum of Natural History.

This work was funded in part by the American Museum of Natural History’s Richard Gilder Graduate Research Fellowship, The Linda Gormezano Memorial Fund research grant, the Society for Systematic Biologists graduate student research grant, and NSF/NASA Dimensions US-Biota-Sa?o Paulo grant # 1241066.

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Now, researchers have a new explanation for the two-faced Moon — one that relates to a giant impact billions of years ago near the Moon’s south pole.

A new study published in the journal Science Advances shows that the impact that formed the Moon’s giant South Pole-Aitken (SPA) basin would have created a massive plume of heat that propagated through the lunar interior. That plume would have carried certain materials — a suite of rare-Earth and heat-producing elements — to the Moon’s nearside. That concentration of elements would have contributed to the volcanism that created the nearside volcanic plains.

“We know that big impacts like the one that formed SPA would create a lot of heat,” said Matt Jones, a Ph.D. candidate at Brown University and the study’s lead author. “The question is how that heat affects the Moon’s interior dynamics. What we show is that under any plausible conditions at the time that SPA formed, it ends up concentrating these heat-producing elements on the nearside. We expect that this contributed to the mantle melting that produced the lava flows we see on the surface.”

The study was a collaboration between Jones and his advisor Alexander Evans, an assistant professor at Brown, along with researchers from Purdue University, the Lunar and Planetary Science Laboratory in Arizona, Stanford University and NASA’s Jet Propulsion Laboratory.

The differences between the near and far sides of the Moon were first revealed in the 1960s by the Soviet Luna missions and the U.S. Apollo program. While the differences in volcanic deposits are plain to see, future missions would reveal differences in the geochemical composition as well. The nearside is home to a compositional anomaly known as the Procellarum KREEP terrane (PKT) — a concentration of potassium (K), rare earth elements (REE), phosphorus (P), along with heat-producing elements like thorium. KREEP seems to be concentrated in and around Oceanus Procellarum, the largest of the nearside volcanic plains, but is sparse elsewhere on the Moon.

Some scientists have suspected a connection between the PKT and the nearside lava flows, but the question of why that suite of elements was concentrated on the nearside remained. This new study provides an explanation that is connected to the South Pole-Aitken basin, the second largest known impact crater in the solar system.

For the study, the researchers conducted computer simulations of how heat generated by a giant impact would alter patterns of convection in the Moon’s interior, and how that might redistribute KREEP material in the lunar mantle. KREEP is thought to represent the last part of the mantle to solidify after the Moon’s formation. As such, it likely formed the outermost layer of mantle, just beneath the lunar crust. Models of the lunar interior suggest that it should have been more or less evenly distributed beneath the surface. But this new model shows that the uniform distribution would be disrupted by the heat plume from the SPA impact.

According to the model, the KREEP material would have ridden the wave of heat emanating from the SPA impact zone like a surfer. As the heat plume spread beneath the Moon’s crust, that material was eventually delivered en masse to the nearside. The team ran simulations for a number of different impact scenarios, from dead-on hit to a glancing blow. While each produced differing heat patterns and mobilized KREEP to varying degrees, all created KREEP concentrations on the nearside, consistent with the PKT anomaly.

The researchers say the work provides a credible explanation for one of the Moon’s most enduring mysteries.

“How the PKT formed is arguably the most significant open question in lunar science,” Jones said. “And the South Pole-Aitken impact is one of the most significant events in lunar history. This work brings those two things together, and I think our results are really exciting.”

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“The gut microbiome is the ecosystem of microbial life that populates an animal’s digestive system — and this microbiome plays a major role in an animal’s well-being,” says Erin McKenney, co-author of a paper on the work and an assistant professor of applied ecology at North Carolina State University. “Everything we learn about these microbiomes helps us make more informed decisions to support the health of wildlife species.”

“The Alaska wilderness, important habitat for brown bears, is changing,” says Grant Hilderbrand, co-author of the study and associate regional director for resources for the National Park Service in Alaska. “The gut microbiome serves as a new diagnostic tool for understanding the health of wildlife populations. It can also help us predict how animal health will change as the environment changes. The study we’ve done here lays the foundation for advancing our understanding of gut microbiomes in Alaska’s iconic brown bears.”

The researchers launched the project with the goal of characterizing what the gut microbiome of Alaskan brown bears looks like.

“Bears are particularly interesting in this context, because they’re omnivores,” says Diana Lafferty, co-author of the paper and an assistant professor of biology at Northern Michigan University. “Bears function as predators and as scavengers, and they have a relatively simple gut system — which means their microbiome may play a particularly important role in helping them extract nutrients from their diet. With this project, we wanted to establish a baseline of what ‘healthy’ microbiomes look like for these animals, which are relatively undisturbed.”

The researchers also benefited from piggybacking on other research efforts that were already underway. The National Park Service was already engaged in research projects that involved tracking and observing wild brown bears at three national parks and preserves: Katmai; Lake Clark; and Gates of the Arctic.

“By collaborating with ongoing projects, we were able to collect all of the data and samples at no additional cost,” Hilderbrand says.

For this study, the researchers analyzed 66 fecal samples from 51 brown bears that were sampled during previous research operations. Because these samples were collected as part of ongoing research initiatives, the researchers also had data on each bear’s age, sex, size and body condition.

The researchers extracted microbial DNA from the fecal samples, and assessed those results to determine what kinds of microbes were in each sample.

“We found significant differences in the diversity of the bears’ microbiomes at each of the three parks,” says Sarah Trujillo, corresponding author of the paper who worked on the study while a graduate student at NMU. “Katmai had the most diversity, and also had the most diverse array of food sources available. Gates of the Arctic, which had the most limited array of food resources, also had bears with the least diverse gut microbiomes. In other words, we found what we expected: the more diverse the diet, the more diverse the gut microbiome.

“However, while we found clear distinctions in microbiome diversity at each park, those differences could not be fully explained by diet alone. There appears to be something else at play that we don’t fully understand yet. That’s an area for future research.”

The work was done with support from Northern Michigan University and the National Park Service.

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Materials provided by North Carolina State University. Original written by Matt Shipman. Note: Content may be edited for style and length.

Published today in Science Advances, the study reveals rapid degradation in air quality and increases in urban exposure to air pollutants hazardous to health. Across all the cities, the authors found significant annual increases in pollutants directly hazardous to health of up to 14% for nitrogen dioxide (NO₂) and up to 8% for fine particles (PM_2.5), as well as increases in precursors of PM_2.5 of up to 12% for ammonia and up to 11% for reactive volatile organic compounds.

The researchers attributed this rapid degradation in air quality to emerging industries and residential sources like road traffic, waste burning, and widespread use of charcoal and fuelwood.

Lead author Dr Karn Vohra (UCL Geography), who completed the study as a PhD student at the University of Birmingham, said: “Open burning of biomass for land clearance and agricultural waste disposal has in the past overwhelmingly dominated air pollution in the tropics. Our analysis suggests we’re entering a new era of air pollution in these cities, with some experiencing rates of degradation in a year that other cities experience in a decade.”

The scientists also found 1.5- to 4- fold increases in urban population exposure to air pollution over the study period in 40 of the 46 cities for NO₂ and 33 of the 46 cities for PM_2.5., caused by a combination of population growth and rapid deterioration in air quality.

According to the study, the increase in the number of people dying prematurely from exposure to air pollution was highest in cities in South Asia, in particular Dhaka, Bangladesh (totalling 24,000 people), and the Indian cities of Mumbai, Bangalore, Kolkata, Hyderabad, Chennai, Surat, Pune and Ahmedabad (totalling 100,000 people).

The researchers say that while the number of deaths in tropical cities in Africa are currently lower due to recent improvements in healthcare across the continent resulting in a decline in overall premature mortality, the worst effects of air pollution on health will likely occur in the coming decades.

Study co-author Dr Eloise Marais (UCL Geography) said: “We continue to shift air pollution from one region to the next, rather than learning from errors of the past and ensuring rapid industrialisation and economic development don’t harm public health. We hope our results will incentivise preventative action in the tropics.”

The study was funded by a University of Birmingham Global Challenges PhD Studentship awarded to Dr Vohra and a NERC/EPSRC grant awarded to Dr Marais.

*Cities analysed in the study:

• Africa — Abidjan, Abuja, Addis Ababa, Antananarivo, Bamako, Blantyre, Conakry, Dakar, Dar es Salaam, Ibadan, Kaduna, Kampala, Kano, Khartoum, Kigali, Kinshasa, Lagos, Lilongwe, Luanda, Lubumbashi, Lusaka, Mombasa, N’Djamena, Nairobi, Niamey, Ouagadougou.
• South Asia — Ahmedabad, Bangalore, Chennai, Chittagong, Dhaka, Hyderabad, Karachi, Kolkata, Mumbai, Pune, Surat.
• Southeast Asia — Bangkok, Hanoi, Ho Chi Minh City, Jakarta, Manila, Phnom Penh, Yangon.
• Middle East — Riyadh, Sana’a.

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The study was published online April 6 in Nature.

“Previously, we knew that Gram-negative bacteria construct their outer membrane with two main, non-protein components — lipids and sugars — which together form an impermeable barrier. The missing link was how this lipopolysaccharide component comes together,” says Filippo Mancia, PhD, a co-leader of the study and professor of physiology & cellular biophysics at Columbia University Vagelos College of Physicians and Surgeons.

Using cutting-edge single-particle cryo-electron microscopy, Mancia and colleagues were able to determine the structures of the enzyme that links together the lipids and sugars (called an O-antigen ligase), in two different functional configurations. Then, combining genetic, biochemical, and molecular dynamics experiments, the team learned how the enzyme positions the lipids and sugars so that they can combine to form the protective membrane.

The lipopolysaccharide component of the outer membrane is critical to the survival of Gram-negative bacteria. “If you could block its assembly, then you would make the bacteria more sensitive to antibiotics and more vulnerable to the immune system,” Mancia says.

Construction of this membrane is an ongoing process, beginning when Gram-negative bacteria are first formed and continuing as the membrane naturally degrades and requires repair. “This means that we would have many opportunities to disrupt the membrane, not just at one stage of the bacteria’s life cycle,” Mancia says.

After revealing the structure of the enzyme that performs the last and critical step in assembling lipopolysaccharide barriers in drug-resistant bacteria, the researchers may begin to custom-design drugs that inhibit the biosynthesis of this protective membrane.

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