Gold nanoparticles cut dendrite growth in zinc batteries, boosting lifespan to over 6000 hours in lab tests.
Get the latest international news and world events from around the world.
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.
Transcranial magnetic stimulation can target a deep brain region without surgery or medication
Neuroscientists at University of Iowa Health Care have demonstrated for the first time that noninvasive brain stimulation can alter the activity of a critical deep brain region involved in emotion and memory. Moreover, the study shows that personalizing the stimulation site using a patient’s unique brain connectivity pathway can increase the neuromodulation effect.
The study, published recently in Nature Communications, used innovative, concurrent brain stimulation and recording techniques in people to provide direct human evidence that noninvasive transcranial magnetic stimulation (TMS) can reliably engage and modulate activity in the hippocampus.
The hippocampus is a deep brain region that plays a critical role in multiple brain functions, such as memory and emotion. Problems with hippocampal function have been implicated in several neurological and neuropsychiatric conditions, including Alzheimer’s disease, depression, anxiety, and post-traumatic stress disorder (PTSD).
Oatk: a de novo assembly tool for complex plant organelle genomes
Plant organelle genomes, particularly large mitochondrial genomes with complex repeats, present significant challenges for assembly. The advent of long-read sequencing enables the assembly of complete genomes, but problems of resolving alternative structures remain. Here we introduce a novel tool that employs a syncmer-based assembler for rapid assembly graph construction, integrates a profile-HMM database for robust organelle identification, and leverages a new search method to find the best supported path through the assembly graph. We describe high-quality organelle assemblies for 195 plant species, demonstrating improvements over other methods, and providing multiple insights into structural complexity, heteroplasmy, and DNA exchange between organelles.
Association of White Matter Hyperintensities, Regional Brain Glucose Metabolism, and Cognitive Impairment in Aβ-Negative Patients
This study examined whether periventricular white matter hyperintensities relate to region-specific cortical hypometabolism and metabolism mediates domain-specific cognition in Aβ-negative individuals.
Letters to the Editor.
The Letters section represents an opportunity for ongoing author debate and post-publication peer review. View our submission guidelines for Letters to the Editor before submitting your comment.
Expert in Anti-Aging Dr. Ronald Klatz Discusses Chronic Disease — Redefining Medicine
Today’s episode on Redefining Medicine features Ronald Klatz, MD, DO. As Founder and President of the American Academy of Anti-Aging Medicine, and leading authority in the field of anti-aging, Dr. Klatz has helped pioneer the exploration of new therapies and treatments for the prevention of chronic disease, and other disorders associated with aging. Dr. Klatz has also been instrumental in founding the National Academy of Sports Medicine, and continues to provide oversight for continuing medical education programs, activities, and publications. #antiaging #regenerativemedicine #wellness #sportsmedicine #Innovation #wellness #functionalmedicine
