Phys.org July 16, 2021 To understand how fast excited electrons in the bulk and on the surface of Sb react to the external energy input, and to explore the mechanisms governing their response an international team of researchers (Germany, Russia, Ireland) used time-, spin- and angle-resolved photoemission to femtosecond-laser excitation. The data showed a ‘kink’ structure in transiently occupied energy-momentum dispersion of surface states, which can be interpreted as an increase in effective electron mass. They were able to show that this mass enhancement plays a decisive role in determining the complex interplay in the dynamical behaviors of electrons from […]
Global satellite data shows clouds will amplify global heating
Phys.org July 19, 2021 Researchers in the UK used data from Earth observations and climate model simulations to develop a statistical learning analysis of how clouds respond to changes in the environment. They showed that global cloud feedback is dominated by the sensitivity of clouds to surface temperature and tropospheric stability. Considering changes in just these two factors, they were able to constrain global cloud feedback to 0.43 ± 0.35 W⋅m−2⋅K−1 (90% confidence), implying a robustly amplifying effect of clouds on global warming and only a 0.5% chance of Equilibrium Climate Sensitivity below 2 K. The “cloud feedback” is the […]
Low-cost, sustainable, readily available plasma technology could replace one of the world’s rarest materials
Nanowerk July 19, 2021 An international team of researchers (Australia, China) has developed a plasma-generated, hybrid nanocomposite material which is free of indium. They used high power impulse magnetron sputtering (HiPIMS) technology to deposit the internal WO3 layer and the external Ag/WO3 nanocomposite. High rates of silver ionization in the HiPIMS process and energetic arrival of silver ions on the negatively biased dielectric/metal/dielectric structure enabled their penetration into the external tungsten oxide layer, forming a nanocomposite structure in a single-step process. This nanotechnology-enabled approach allows electrochromic devices to change colour efficiently and rapidly upon a user’s request and offers a […]
Making clean hydrogen is hard, but researchers just solved a major hurdle
Phys.org July 19, 2021 To create electrically conductive paths through a thick silicon dioxide researchers at UT Austin used a technique first deployed in the manufacturing of semiconductor electronic chips. By coating the silicon dioxide layer with a thin film of aluminum and heating the entire structure, arrays of nanoscale “spikes” of aluminum that completely bridge the silicon dioxide layer were created. These can be replaced by nickel or other materials that help catalyze the water-splitting reactions. When illuminated by sunlight, the devices efficiently oxidized water to form oxygen molecules while also generating hydrogen at a separate electrode and exhibited […]
Microbially produced fibers: Stronger than steel, tougher than Kevlar
Phys.org July 21, 2021 A problem associated with recombinant spider silk fiber is the need to create β-nanocrystals, a main component of natural spider silk, which contributes to its strength. Researchers at Washington University redesigned the silk sequence by introducing amyloid sequences that have high tendency to form β-nanocrystals. They created different polymeric amyloid proteins using three well-studied amyloid sequences as representatives. The resulting proteins had less repetitive amino acid sequences than spider silk, making them easier to be produced by engineered bacteria. The longer the protein, the stronger and tougher the resulting fiber. The 128-repeat proteins resulted in a […]
Nanostructures enable record high-harmonic generation
Phys.org July 21, 2021 Resonantly enhanced High harmonic generation (HHG) from hot spots in nanostructures is an attractive route to overcoming the well-known limitations of gases and bulk solids. An international team of researchers (USA – Cornell University, Ohio State University, Singapore) demonstrated an ultra-thin resonant gallium phosphide platform for highly efficient HHG driven by intense mid-infrared laser pulses. The gallium-phosphide material permits harmonics of all orders without reabsorbing them, and the specialized structure can interact with the laser pulse’s entire light spectrum. The enhanced conversion efficiency facilitates single-shot measurements that avoid material damage and pave the way to study […]
New material could mean lightweight armor, protective coatings
Science Daily July 19, 2021 An international team of researchers (USA – MIT, Caltech, Switzerland) has fabricated nanoarchitectured materials, that absorb the impact of microscopic projectiles accelerated to supersonic speeds. According to their calculations the new material absorbs impacts more efficiently than steel, Kevlar, aluminum, and other impact-resistant materials of comparable weight. Tests revealed that consistent mechanisms such as compaction cratering and microparticle capture enable this superior response. They introduced predictive tools for crater formation in these materials using dimensional analysis. These results substantially uncover the dynamic regime over which nanoarchitecture enables the design of ultralightweight, impact-resistant materials that could […]
New method predicts ‘stealth’ solar storms before they wreak geomagnetic havoc on Earth
Phys.org July 20, 2021 Unlike coronal mass ejections which typically show up clearly on the Sun as dimming or brightening, the ‘stealth CMEs’ often originate at higher altitudes in the Sun’s corona, in regions with weaker magnetic fields and they are usually only visible on coronagraphs designed to reveal the corona. An international team of researchers (USA – UC Berkeley, industry, University of Maryland, NASA, Belgium, Romania, UK, India, Russia) has shown that many stealth CMEs can be detected in time if current analysis methods for remote sensing are adapted. They compared remote sensing images of the Sun with the […]
Novel coronavirus discovered in British bats
Science Daily July 19, 2021 Researchers in the UK have identified and sequenced a novel sarbecovirus (RhGB01) from a British horseshoe bat at the western extreme of the rhinolophid range. Their results extend both the geographic and species ranges of sarbecoviruses and suggest their presence throughout the horseshoe bat distribution. Within the spike protein receptor binding domain, but excluding the receptor binding motif, RhGB01 has a 77% (SARS-CoV-2) and 81% (SARS-CoV) amino acid homology. While apparently lacking hACE2 binding ability, and hence unlikely to be zoonotic without mutation, RhGB01 presents opportunity for SARS-CoV-2 and other sarbecovirus homologous recombination. Their findings […]
The paradox of a free-electron laser without the laser
Phys.org July 16, 2021 An international team of researchers (UK, the Netherlands) conducted a proof-of-principle experiment in the ultraviolet spectral range to demonstrate a new way of producing coherent light. In FELs the intensity of light is amplified by a feedback mechanism that locks the phases of individual radiators. This is achieved by passing a high energy electron beam through the undulator. As they wiggle through the undulator light emitted from the electrons bunch together causing amplification of the light and the increase in its coherence. If the electron bunch is shorter than the wavelength of the light produced by […]