Phys.org September 18, 2023 Due to the lack of long homogenous climate data and methodological frameworks, it is challenging to estimate how extreme precipitation could get and what the physical drivers are. Researchers in Switzerland developed two complementary strategies to extrapolate beyond the precipitation records: (a) statistical estimates based on fitting generalized extreme value distributions, providing their probabilistic information on return periods and, (b) ensemble boosting, a model-based re-initialization of heavy precipitation in large ensembles, providing a physical coherent storyline in space and time, however, with no direct quantification of its probability. Both show that 3-day accumulated precipitation maxima can […]
Generating biskyrmions in a rare earth magnet
Phys.org September 16, 2023 The low stability of most magnetic skyrmions leads to either a narrow temperature range in which they can exist, a low density of skyrmions, or the need for an external magnetic field, which greatly limits their wide application. An international team of researchers (USA – NIST, Japan, South Korea) has reported real-space imaging of a two-dimensional skyrmion lattice in a thin film of Fe0.5Co0.5Si using Lorentz transmission electron microscopy. With a magnetic field of 50–70 mT applied normal to the film, they observed skyrmions in the form of a hexagonal arrangement of swirling spin textures, with a […]
Near-surface permafrost could be nearly gone by 2100, scientists conclude
Phys.org September 19, 2023 Accurate understanding of permafrost dynamics is critical for evaluating and mitigating impacts that may arise as permafrost degrades in the future; however, existing projections have large uncertainties. To better understand how near‐surface permafrost may respond to future warming, an international team of researchers (US – University of Alaska, NCAR, University of Connecticut, Columbia University, — UK, Germany, Japan, Canada, France, the Netherlands, Sweden) combined a surface frost index model with outputs from the second phase of the Pliocene Model Intercomparison Project to simulate the near‐surface (~3 to 4 m depth) permafrost state in the Northern Hemisphere […]
New method improves accuracy and resolution of lightning observations
Phys.org September 12, 2023 Despite some advances in existing observational techniques, scientists have continued to strive for higher accuracy in analyzing the complex phenomenon of lightning. To improve the accuracy and resolution of lightning observations researchers at the New Mexico Institute of Mining and Technology optimized the very-high-frequency signal from the interferometer using the double-sided mirror and ensemble empirical mode decomposition method to perform quality control and band-pass truncation on the raw signal. By combining the main window with the auxiliary window, they achieved waveform matching of signals from different antennas based on the generalized cross-correlation method. They obtained the […]
Plumbing the depths of thermoelectrics in search of novel materials
Phys.org September 18, 2023 Although historically the thermoelectric effect was first discovered in metals, state-of-the-art research focuses on semiconductors. An international team of researchers (Austria, Japan) discovered unprecedented thermoelectric performance in metals and realized ultrahigh power factors in binary nickel and gold alloys, more than twice larger than in any bulk material above room temperature. In metallic NixAu1–x alloys, large Seebeck coefficients originated from electron-hole selective scattering of Au s electrons into more localized Ni d states. This intrinsic energy filtering effect owing to the unique band structure yielded a strongly energy-dependent carrier mobility. While the metastable nature of the […]
Researchers develop high-performance zero thermal expansion composite for precision devices
Phys.org September 14, 2023 Negative thermal expansion (NTE) materials can be applied to suppress thermal expansion of other materials, forming composites with zero thermal expansion (ZTE). However, the shortcomings (e.g., high density, narrow working temperature window) inherited from various NTE materials hinder the applications of corresponding ZTE composites. An international team of researchers (China, Poland) used modified Cu2P2O7 by reducing oxygen deficiencies, which had a relatively low density and strong NTE over a wide temperature range, to composite with 2024Al. When the volume content of modified Cu2P2O7 was about 50%, the composite Cu2P2O7/2024Al showed ZTE effect, and the linear coefficient […]
Scientists uncover mystery of important material for semiconductors at the surface
Nanowerk September 16, 2023 Ferroelectricity in binary oxides including hafnia and zirconia is interesting because of their unconventional physical mechanisms and the potential for the integration of these materials into semiconductor workflows. Behaviors such as wake-up phenomena and an extreme sensitivity to electrode and processing conditions suggest that ferroelectricity in these materials is strongly influenced by other factors, including electrochemical boundary conditions and strain. An international team of researchers (USA – Oak Ridge National Laboratory, University of Virginia, Charlottesville, Carnegie Mellon University, University of Tennessee, Knoxville, Ukraine) argued that the properties of these materials emerge due to the interplay between […]
Synthesis of Clean Hydrogen Gas from Waste Plastic at Zero Net Cost
Science Daily September 14, 2023 Hydrogen gas is the primary storable fuel for pollution-free energy production, with over 90 million tonnes used globally per year. More than 95% of H2 is synthesized through metal-catalyzed steam methane reforming that produces 11 tonnes of CO2 per tonne H2. “Green H2” from water electrolysis using renewable energy evolves no CO2, but costs 2–3x more, making it presently economically unviable. Researchers at Rice University have demonstrated catalyst-free conversion of waste plastic into clean H2 along with high purity graphene. The scalable procedure evolved no CO2 when deconstructing polyolefins and produces H2 in purities up […]
Scientists develop self-healing elastomer for flexible electronics
Phys.org September 18, 2023 The mechanical properties of the substrate elastomers are often poor due to the inherent performance of the materials. Researchers in China prepared a poly(vinyl alcohol) (PVA)-based self-healing material with high strength and good thermal stability by side-linked grafting modification of PVA with a one-step esterification reaction. Benefiting from the hydrogen bonds and ion coordination between iron ions and carboxyl groups, the synthesized elastomer exhibited excellent mechanical properties and good self-healing performance. The high sensitivity and self-healing performance of a silver nanowire-coated elastomer strain sensor demonstrated the wide potential applicability of the prepared PVA-based elastomers in health […]
Unveiling the invisible: A bioinspired CMOS-integrated polarization imaging sensor
Phys.org September 18, 2023 Chip-integrated, fast, cost-effective, and accurate full-Stokes polarimetric imaging sensors are highly desirable in many applications, but they remain elusive due to fundamental material limitations. Researchers at the State University of Arizona have developed a chip-integrated Metasurface-based Full-Stokes Polarimetric Imaging sensor (MetaPolarIm) by integrating an ultrathin (~600 nm) metasurface polarization filter array (MPFA) onto a visible imaging sensor with CMOS compatible fabrication processes. The MPFA has broadband dielectric-metal hybrid chiral metasurfaces and double-layer nanograting polarizers. This chip-integrated polarimetric imaging sensor enabled single-shot full-Stokes imaging (speed limited by the CMOS imager) with the most compact form factor, recorded high […]