. Scientific Frontline

Monday, October 31, 2022

New catalyst can turn smelly hydrogen sulfide into a cash cow

An illustration of the light-powered, one-step remediation process for hydrogen sulfide gas made possible by a gold photocatalyst created at Rice University.
Image Credit: Halas Group/Rice University

Hydrogen sulfide gas has the unmistakable aroma of rotten eggs. It often emanates from sewers, stockyards and landfills, but it is particularly problematic for refineries, petrochemical plants and other industries, which make thousands of tons of the noxious gas each year as a byproduct of processes that remove sulfur from petroleum, natural gas, coal and other products.

In a published study in the American Chemical Society’s high-impact journal ACS Energy Letters, Rice engineer, physicist and chemist Naomi Halas and collaborators describe a method that uses gold nanoparticles to convert hydrogen sulfide into high-demand hydrogen gas and sulfur in a single step. Better yet, the one-step process gets all its energy from light. Study co-authors include Rice’s Peter Nordlander, Princeton University’s Emily Carter and Syzygy Plasmonics’ Hossein Robatjazi.

“Hydrogen sulfide emissions can result in hefty fines for industry, but remediation is also very expensive,” said Halas, a nanophotonics pioneer whose lab has spent years developing commercially viable light-activated nanocatalysts. “The phrase ‘game-changer’ is overused, but in this case, it applies. Implementing plasmonic photocatalysis should be far less expensive than traditional remediation, and it has the added potential of transforming a costly burden into an increasingly valuable commodity.”

Bulking Up to Beat Bacteria

The inhibitor-binding site of the wild-type MexB pump. (a) The crystal structure of the inhibitor ABI-PP bound to the MexB trimer. Three MexB monomers are shown in green, blue, and red, representing the access, binding, and extrusion monomer, respectively. ABI-PP is shown as a yellow space-filling model. (b) A close-up view of the inhibitor binding site. The substrate translocation pathway is shown as a solid gray surface. The proximal and distal binding pockets are indicated in green and blue circles, respectively. The inhibitor binding pit is shown as a red surface. The ABI-PP molecule is represented as a yellow stick model. (c) A detailed view of the inhibitor-binding site. Carbon atoms of ABI-PP are indicated in yellow while amino acid residues are indicated in green. The classification of these amino acids is shown on the right side of the panel.
Image Credit: 2022 Yamasaki et al., Spatial Characteristics of the Efflux Pump MexB Determine Inhibitor Binding, Antimicrobial Agents and Chemotherapy

The medical profession is in the midst of losing an arms race. Bacterial antibiotic resistance doesn’t just threaten our ability to treat infection but our ability to carry out any treatment where infection is a risk. This includes a raft of life-saving surgeries ranging from coronary bypass operations to organ transplantation. In fact, the number of new antimicrobials being developed is declining each year. Understanding how bacteria resist the influence of antibiotics is essential to winning this arms race: it is time to make up ground.

In a study published this month in Antimicrobial Agents and Chemotherapy, researchers at Osaka University have produced new insights into the structure of a particular bacterial protein known as an efflux pump. This protein is involved in antibiotic resistance and its structure influences the ability of drugs to target it.

New MicroBooNE analysis takes a closer look at the sterile neutrino

MicroBooNE features state-of-the-art particle detection techniques and technology. The experiment studies neutrino interactions and is probing models of a theorized fourth neutrino called the sterile neutrino.
Photo Credit: Reidar Hahn, Fermilab

A new result from the MicroBooNE experiment at the U.S. Department of Energy’s Fermi National Accelerator Laboratory probes the Standard Model — scientists’ best theory of how the universe works. The model assumes there are three kinds of neutrinos. Yet for more than two decades, a proposed fourth kind of neutrino has remained a promising explanation for anomalies seen in earlier physics experiments. Finding the theorized sterile neutrino would be a major discovery and radical shift in our understanding of the universe.

The new analysis published in arXiv compares the experiment’s data to a model with a fourth, sterile neutrino to test their compatibility. MicroBooNE scientists found no evidence of the long-sought sterile neutrino in the parameter range explored.

The possibility that sterile neutrinos caused the yet-unexplained anomalies reported by previous experiments still remains. These include measurements by the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory, the MiniBooNE experiment at Fermilab, and several radiochemical and nuclear reactor neutrino experiments.

“This is the first time we’ve checked whether our data fit a specific sterile-neutrino model,” said Matt Toups, a Fermilab scientist and co-spokesperson for MicroBooNE. “We’ve excluded large sections of the sterile neutrino parameter space allowed by LSND. But there are still corners where a sterile neutrino could potentially be hiding.”

Reprogramming of immune cells shown to fight off melanoma

Illustration showing how miniature artificial protocells loaded with anti-microRNA-223 cargo can reprogram cancer-associated macrophages in larval and adult zebrafish leading them to be more pro-inflammatory and thus able to drive melanoma shrinkage
Image Credit: Paco Lopez Cuevas

A new way of reprogramming our immune cells to shrink or kill off cancer cells has been shown to work in the otherwise hard to treat and devastating skin cancer, melanoma. The University of Bristol-led discovery, published in Advanced Science today [31 October], demonstrates a new way to clear early stage pre-cancerous and even late-stage tumor cells.

Using miniature artificial capsules called protocells designed to deploy reprogramming cargoes that are taken up by inflammatory cells (white blood cells), the scientists show they were able to transform these cells into a state that makes them more effective at slowing down the growth and killing of melanoma cells. They showed that this was possible for both animal and human immune cells.

The study is the first to test the capacity of a protocell to deliver cargoes for reprogramming immune cells and offers a promising novel target for the development of cancer immunotherapies.

Paul Martin, Professor of Cell Biology in the School of Biochemistry at the University of Bristol and one of the study's lead authors explained what happens when our immune system comes into contact with cancer cells: "Our immune cells have a surveillance capacity which enables them to detect pre-cancerous cells arising at any tissue site in the body. However, when immune cells encounter cancer cells, they are often subverted by the cancer cells and instead tend to nourish them and encourage cancer progression. We wanted to test whether it might be possible to reprogram our immune system to kill these cells rather than nurture them."

New Tech Solves Longstanding Challenges for Self-Healing Materials

3D printed thermoplastic on woven-carbon fiber reinforcement.
Credit: North Carolina State University

Engineering researchers have developed a new self-healing composite that allows structures to repair themselves in place, without having to be removed from service. This latest technology resolves two longstanding challenges for self-healing materials, and can significantly extend the lifespan of structural components such as wind-turbine blades and aircraft wings.

“Researchers have developed a variety of self-healing materials, but previous strategies for self-healing composites have faced two practical challenges,” says Jason Patrick, corresponding author of the research paper and an assistant professor of civil, construction and environmental engineering at North Carolina State University.

“First, the materials often need to be removed from service in order to heal. For instance, some require heating in an oven, which can’t be done for large components or while a given part is in use. Second, self-healing only works for a limited period. For example, the material might be able to heal a few times, after which its self-repairing properties would significantly diminish. We’ve come up with an approach that addresses both of those challenges in a meaningful way, while retaining the strength and other performance characteristics of structural fiber-composites.”

Largest Potentially Hazardous Asteroid Detected in Eight Years

Twilight observations with the U.S. Department of Energy-fabricated Dark Energy Camera at Cerro Tololo Inter-American Observatory in Chile, a program of NSF’s NOIRLab, have enabled astronomers to spot three near-Earth asteroids, or NEAs, hiding in the glare of the sun. These NEAs are part of an elusive population that lurks inside the orbits of Earth and Venus. One of the asteroids is the largest object that is potentially hazardous to Earth to be discovered in the last eight years.
Image Credit: DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA/J. da Silva/Spaceengine

Twilight observations with the US Department of Energy-fabricated Dark Energy Camera at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF's NOIRLab, have enabled astronomers to spot three near-Earth asteroids (NEA) hiding in the glare of the Sun. These NEAs are part of an elusive population that lurks inside the orbits of Earth and Venus. One of the asteroids is the largest object that is potentially hazardous to Earth to be discovered in the last eight years.

An international team using the Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF’s NOIRLab, has discovered three new near-Earth asteroids (NEAs) hiding in the inner Solar System, the region interior to the orbits of Earth and Venus. This is a notoriously challenging region for observations because asteroid hunters have to contend with the glare of the Sun.

By taking advantage of the brief yet favorable observing conditions during twilight, however, the astronomers found an elusive trio of NEAs. One is a 1.5-kilometer-wide asteroid called 2022 AP7, which has an orbit that may someday place it in Earth’s path. The other asteroids, called 2021 LJ4 and 2021 PH27, have orbits that safely remain completely interior to Earth’s orbit. Also, of special interest to astronomers and astrophysicists, 2021 PH27 is the closest known asteroid to the Sun. As such, it has the largest general-relativity effects [1] of any object in our Solar System and during its orbit its surface gets hot enough to melt lead.

Ghost of a giant star

This image shows a spectacular view of the orange and pink clouds that make up what remains after the explosive death of a massive star — the Vela supernova remnant. This detailed image consists of 554 million pixels, and is a combined mosaic image of observations taken with the 268-million-pixel OmegaCAM camera at the VLT Survey Telescope, hosted at ESO’s Paranal Observatory.   OmegaCAM can take images through several filters that each let the telescope see the light emitted in a distinct color. To capture this image, four filters have been used, represented here by a combination of magenta, blue, green and red. The result is an extremely detailed and stunning view of both the gaseous filaments in the remnant and the foreground bright blue stars that add sparkle to the image. 
Hi-Res Zoomable Image
Credit: ESO/VPHAS+ team. Acknowledgement: Cambridge Astronomical Survey Unit

A spooky spider web, magical dragons or wispy trails of ghosts? What do you see in this image of the Vela supernova remnant? This beautiful tapestry of colors shows the ghostly remains of a gigantic star, and was captured here in incredible detail with the VLT Survey Telescope, hosted at the European Southern Observatory’s (ESO’s) Paranal site in Chile.

The wispy structure of pink and orange clouds is all that remains of a massive star that ended its life in a powerful explosion around 11 000 years ago. When the most massive stars reach the end of their life, they often go out with a bang, in an outburst called a supernova. These explosions cause shock waves that move through the surrounding gas, compressing it and creating intricate thread-like structures. The energy released heats the gaseous tendrils, making them shine brightly, as seen in this image.

In this 554-million-pixel image, we get an extremely detailed view of the Vela supernova remnant, named after the southern constellation Vela (The Sails). You could fit nine full Moons in this entire image, and the whole cloud is even larger. At only 800 light-years away from Earth, this dramatic supernova remnant is one of the closest known to us.

A better way to tell which species are vulnerable

Intertidal ecosystems containing species of mussels, barnacles, and algae were one of the systems with fluctuating populations analyzed by the team. They developed a new way to detect species that are vulnerable to perturbations, such as waves and storms that affect intertidal ecosystems.
Credits: Courtesy of the researchers | Massachusetts Institute of Technology

Wildfires, floods, pollution, and overfishing are among the many disruptions that can change the balance of ecosystems, sometimes endangering the future of entire species. But evaluating these ecosystems to determine which species are most at risk, in order to focus preservation actions and policies where they are most needed, is a challenging task.

Most such efforts assume that ecosystems are essentially in a state of equilibrium, and that external perturbations cause a temporary shift before things eventually return to that equilibrium state. But that assumption fails to account for the reality that ecosystems are often in flux, with the relative abundances of their different components shifting on timetables of their own. Now, a team of researchers at MIT and elsewhere have come up with a better, predictive way of evaluating these systems in order to rank the relative vulnerabilities of different species, and to detect species that are under threat but could otherwise go unnoticed.

Contrary to conventional ways of making such rankings today, they found, the species with the lowest population numbers or the steepest decline in numbers — criteria typically used today — are sometimes not the ones most at risk.

The findings are reported today in the journal Ecology Letters, in a paper by MIT associate professor of civil and environmental engineering Serguei Saavedra, recent doctoral student Lucas Medeiros PhD ’22, and three others.

Just like humans, more intelligent jays have greater self-control

A study has found that Eurasian jays can pass a version of the ‘marshmallow test’ – and those with the greatest self-control also score the highest on intelligence tests.
Photo Credit: Takashi Yanagisawa

This is the first evidence of a link between self-control and intelligence in birds.

Self-control - the ability to resist temptation in favor of a better but delayed reward – is a vital skill that underpins effective decision-making and future planning.

Jays are members of the corvid family, often nicknamed the ‘feathered apes’ because they rival non-human primates in their cognitive abilities. Corvids hide, or ‘cache’, their food to save it for later. In other words, they need to delay immediate gratification to plan for future meals. The researchers think this may have driven the evolution of self-control in these birds.

Self-control has been previously shown to be linked to intelligence in humans, chimpanzees and – in an earlier study by these researchers – in cuttlefish. The greater the intelligence, the greater the self-control.

The new results show that the link between intelligence and self-control exists across distantly related animal groups, suggesting it has evolved independently several times.

Of all the corvids, jays in particular are vulnerable to having their caches stolen by other birds. Self-control also enables them to wait for the right moment to hide their food without being seen or heard.

New Material for Perovskite Solar Cells Proposed in Russia

Scientists have proposed a new type of material for transporting electrons in perovskite solar cells.
 Photo Credit: Vladimir Petrov

Experts from the Ural Federal University and the Institute of Organic Synthesis of the Ural Branch of the Russian Academy of Sciences, together with other Russian scientists, have proposed a new type of material for one of the solar cell cells. The discovered compounds will significantly reduce the cost of solar cell production. An article with the results of the study was published in the New Journal of Chemistry.

Perovskite solar cells (PSCs) are a promising alternative to the familiar silicon cells, providing the same amount of energy with 180 times less material thickness. Their production technology is much simpler and cheaper than that of silicon cells. The problem with PSCs is their lack of stability. One of the most effective solutions today, as explained by the experts, is the selection of new materials that ensure the transport of the charge carriers after it is obtained in the perovskite layer itself.

The scientific team of the Ural Federal University and the Institute of Organic Synthesis of the Ural Branch of the Russian Academy of Sciences proposed a new type of material for transporting electrons in the PSCs, which has a number of advantages. According to the authors, with the new material they managed to achieve solar energy conversion efficiency of 12%, which is comparable with the average indicators of market analogues.

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