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Lab study suggests longer waves fracture floating ice sheets at lower stress

When waves are moving across ice-covered seas, they can cause sheets of ice to bend and ultimately break. Understanding the processes underlying these wave-induced ice fractures and predicting when they will occur could help to better forecast how climate change will impact the environment and marine ecosystems on Earth.

Researchers at PMMH Lab, ESPCI, CNRS, PSL University, Sorbonne Université and Université Paris Cité recently performed a new laboratory experiment aimed at shedding new light on this phenomenon. The results of this experiment, published in Physical Review Letters, suggest that the stress at which ice sheets break depends on the length of the underlying waves.

“Since 2021, we wanted to study the propagation of ocean waves in floating ice, with laboratory-scale experiments, and in particular the fracture of a thin sheet by a surface wave,” said Stéphane Perrard, senior author of the paper, told Phys.org. “We were later inspired by the work of E. Dumas Lefevbre and D. Dumont, who monitored the fracture of a real sea ice layer by the wake of an icebreaker. To study a small-scale analog of their experiment, we used the concept of scale invariance: the same physical phenomenon can occur at very different scales, as long as the key ingredients are conserved across scales.”

Zebrafish reveal new insights into the biology of autism

In recent decades, the zebrafish has become one of the most valuable model organisms in scientific research. For a variety of reasons, including their genetic similarities to humans, these tiny tropical fish have helped researchers unlock secrets to diseases ranging from muscular dystrophy to melanoma. Now, Yale researchers are hoping the zebrafish will do the same for autism spectrum disorder.

In a new study, a research team generated a database of 520 U.S. Food and Drug Administration (FDA)-approved drugs and their effects on basic larval zebrafish behaviors and then used the database to identify drug candidates that reverse disrupted behaviors in zebrafish carrying mutations in autism risk genes.

These drug candidates, the researchers say, might represent targets for people carrying mutations in specific autism risk genes.

Proton-trapping MNene transforms ammonia production for food security and economic growth

With a new electrochemical synthesis via an electrochemical nitrogen reduction reaction (NRR), achieving carbon-free ammonia production is closer to reality through work from Drs. Abdoulaye Djire and Perla Balbuena, chemical engineering professors at Texas A&M University, and graduate students David Kumar and Hao En Lai. A topic outlined in their recent paper published in the Journal of the American Chemical Society introduces NRR, which produces ammonia in a cleaner and simpler way by using renewable electricity.

The research branches off of the team’s previous work, where they looked further into enabling two-dimensional materials in renewable energy.

“The current process of making ammonia is energy intensive and emits a lot of carbon dioxide, so if you can make ammonia electrochemically, then you can avoid these two negative effects,” Djire said. “During the electrochemical NRR process, water provides the hydrogen atoms, which combine with nitrogen from the air to form ammonia, all powered by electricity.”

Aurora begins final assembly of revolutionary X-65 aircraft

Aurora Flight Sciences said the fuselage of its X-65 experimental aircraft has arrived for final systems integration.

The Boeing subsidiary said teams in Virginia are now installing the aircraft’s electrical, propulsion, and active flow control systems, while wing and tail production continues at its facility in West Virginia. The update marks the program’s transition from major structural assembly into the final integration phase ahead of flight testing.

“The X-65 fuselage has arrived! Our teams are now integrating electrical, propulsion, and AFC systems into the aircraft fuselage in Virginia, while wing and tail manufacturing is advancing at our facility in West Virginia,” the company said.

Swift spacecraft reorientation buys time for reboost mission

WASHINGTON — NASA modified operations of an astrophysics spacecraft in a decaying orbit to buy more time for a mission later this year that will attempt to raise its orbit.

NASA announced in September it selected Katalyst Space to develop a spacecraft that will rendezvous with the Neil Gehrels Swift Observatory and raise its orbit. Swift, launched in 2004, is in a decaying orbit, and the $30 million reboost mission would keep the spacecraft from reentering.

At an astronomy conference in early January, Jamie Kennea, a research professor at Penn State University who is head of Swift’s science operations team, said models projected that Swift’s orbit would decay below 300 kilometers, the minimum altitude for the reboost mission, sometime between mid-October 2026 and January 2027. That provided several months of margin for Katalyst’s Link spacecraft, scheduled to launch as soon as June 1 on a Northrop Grumman Pegasus XL.

A New Probe of Nanoparticle Melting

Understanding nanoparticles is important in astrophysics and atmospheric physics and for applications like catalysts. These particles are tough to characterize, but now Vitaly Kresin of the University of Southern California and his colleagues have determined one elusive property with high accuracy. They inferred the melting point of sodium and potassium nanoparticles 7–9 nm in diameter with an accuracy of 1% [1]. They found that the melting point is about 100 K lower than in bulk samples, in agreement with less-precise data on other types of nanoparticles of this size and with theoretical predictions. The technique could potentially provide a new way to probe other properties of nanoparticles having a wide range of sizes.

Metal nanoparticles are known to melt at lower temperatures than bulk samples, but the theory needed to predict the melting point has significant uncertainties. Experiments also face various challenges, such as the tendency of electron microscopes to melt nanoparticles. Kresin and his colleagues suspected that the work function—the energy required to remove an electron from a surface or a nanoparticle—might show some notable changes when a nanoparticle melts, given the major structural rearrangements involved.

Their recently developed setup [2] uses a beam of temperature-controlled nanoparticles targeted by an adjustable-wavelength, monochromatic light source. When the photons eject electrons, the team detects the charged particles. For both sodium and potassium, the work function-versus-temperature data show a clear discontinuity and change in slope at the melting point.

Methane’s Elaborate Phases and Where to Find Them

A systematic exploration of the phase diagram of methane resolves inconsistencies of earlier studies, with potential ramifications for our understanding of planetary interiors.

As a gas, methane is very simple. But as a liquid and as a solid, it is perplexingly complex. Ambiguity has long plagued our observations and measurements of its structure at different pressure–temperature combinations. Yet, understanding methane’s phase diagram is vital for predicting its behavior deep within our and other planets. In a tour de force contribution Mengnan Wang at the University of Edinburgh in the UK and her colleagues have now charted the turbulent seas of the methane phase diagram [1]. By comprehensively mapping its phases and melting curve, they have resolved the legion of discrepancies of earlier studies.

Methane—one of the simplest of all molecules—is sometimes the subject of flatulence jokes (of which it is odorlessly innocent) but is also a powerful driver of climate change on Earth (of which it is very guilty [2]). The extraction of gaseous methane from Earth drives multibillion-dollar industries, which use the molecule both as a fuel and as a source of hydrogen. Out in the Solar System, methane in planetary atmospheres absorbs red light, which makes Uranus and Neptune shine blue, while icy methane damaged by radiation paints dwarf planets red.

Amorphous passivation strategy creates efficient, durable and flexible perovskite solar cells

Solar cells, devices that convert sunlight into electricity, are helping to reduce greenhouse gas emissions worldwide, promoting a shift toward renewable energy sources. Most solar cells used today are based on silicon, yet researchers have recently been exploring the potential of other photovoltaic materials, particularly perovskites.

Perovskites are a class of photovoltaic materials with strong light absorption. In practical devices, perovskite thin films are typically polycrystalline, meaning they consist of many small crystalline grains. As perovskites absorb sunlight so efficiently, a film thinner than ~1 μm can capture most of the incident solar radiation, whereas conventional crystalline silicon usually requires hundreds of micrometers of active material.

This combination of strong absorption and ultrathin active layers makes perovskite thin-film solar cells particularly well suited for lightweight, flexible, high-efficiency photovoltaic devices. Despite these many advantages, perovskites still face inherent challenges, such as achieving true mechanical flexibility, operational stability, and maintaining high efficiency at large areas simultaneously.

First carbon-enhanced metal-poor stars discovered in Milky Way’s companion

Using the Baryons Oscillation Spectroscopic Survey (BOSS) spectrograph, astronomers have discovered five new carbon-enhanced metal-poor stars in the Large Magellanic Cloud (LMC). This is the first time such stars have been identified in this galaxy. The discovery was reported in a paper published January 15 on the arXiv pre-print server.

Metal-poor stars are rare objects, as only a few thousand stars with iron abundances [Fe/H] below-2.0 have been discovered to date. Expanding the still-short list of metal-poor stars is of high importance for astronomers, as such objects have the potential to improve our knowledge of the chemical evolution of the universe.

Observations show that a significant fraction of these stars exhibit a large overabundance of carbon; therefore, they are known as carbon-enhanced metal-poor (CEMP) stars.

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