Science Daily July 12, 2023 Although clear air turbulence (CAT) generation in the free atmosphere has been studied by high-resolution numerical simulations, few studies simulated aircraft-scale turbulence eddies and validated them with high-frequency airborne observation. Researchers in Japan used a regional numerical weather prediction model to simulate the event with fine resolution. They compared the onboard-recorded data with the virtual flight data, to confirm that turbulent eddies were reasonably reproduced. The CAT was largely generated by breaking Kelvin-Helmholtz (KH) instability waves in the free atmosphere. They resolved the KH waves and their breaking. When the resolution was finer, the turbulent […]
Tag Archives: S&T Japan
Magnetic bacteria point the way
Science Daily June 27, 2023 Magnetotactic bacteria contain magnetosomes, iron crystals wrapped in a membrane, which arrange themselves to align with the Earth’s magnetic field, causing the bacteria to travel in the direction of Earth’s magnetic field lines leading north or south. Magnetosome-producing microorganisms can sense and move toward the redox gradient. Researchers in Japan collected a deep-sea hydrothermal vent chimney. The mineralogical and geochemical characterization of the vent chimney sample showed an internal iron redox gradient. The electron microscopy of particles collected from the chimney sample revealed magnetotactic bacteria (MTB) cells with bullet-shaped magnetosomes, and there were minor occurrences […]
Nanosheet technology developed to boost energy storage dielectric capacitors
Science Daily July 4, 2023 Dielectric capacitors can become ideal, safe energy storage devices. However, they yield rather low energy densities compared with other energy storage devices such as batteries and supercapacitors. Researchers in Japan designed ultrahigh energy storage capacitors using two-dimensional (2D) high-κ dielectric perovskites (Ca2Nam–3NbmO3m+1; m = 3–6). Individual Ca2Nam–3NbmO3m+1 nanosheets exhibited an ultrahigh dielectric strength even in the monolayer form, which exceeded those of conventional dielectric materials. Multilayer stacked nanosheet capacitors exhibited ultrahigh energy densities, high efficiencies (>90%), excellent reliability (>107 cycles), and temperature stability (−50–300 °C); the maximum energy density was much higher than those of […]
Researchers discover materials exhibiting huge magnetoresistance
Nanowerk June 9, 2023 Much of the hardware and sensors electronic devices rely on magnetoresistive random access memory (MRAM) and magnetic sensors. In magnetoresistive devices when the magnets are aligned, electrons can easily tunnel through the thin insulating barrier between them making the device efficient; when magnets are not aligned the device is less efficient due to higher resistance. Current tunnel magnetoresistive devices comprise magnesium oxide and iron-based magnetic alloys, like iron-cobalt. Iron-based alloys have a body-centered cubic crystal structure in ambient conditions and exhibit a huge tunnel magnetoresistance effect in devices with a rock salt-type magnesium oxide. Researchers in […]
Unveiling the nanoscale frontier: Innovating with nanoporous model electrodes
Phys.org June 2, 2023 Researchers in Japan have fabricated the next-generation membrane electrodes for fundamental electrochemical research of amorphous-based porous carbon materials by the uniform carbon coating of anodic aluminum oxide formed on an Al substrate and free from a barrier layer. The conformally carbon-coated layer formed vertically aligned giant carbon nanotubes, and their walls comprised low-crystalline stacked graphene sheets. The diameter and the length of the nanopores could be tuned over a broad range of between 10 to 200 nm and 2 to 90 µm, respectively. Unlike composite electrodes made from other ordered nanoporous carbons, this model electrode exhibited […]
Source-shifting metastructures composed of only one resin for location camouflaging
Science Daily May 30, 2023 Researchers in Japan numerically demonstrated an inverse design of a structure for camouflaging the location of a sound source as if the sound emanated from a different location. They used a topology optimization approach used in acoustic elastic coupled problems, the difference between the sound pressure fields emanating from an actual source and a virtual source, was the objective function infimized in camouflaging the sound source. Optimal topologies of elastic structures made of acrylonitrile butadiene styrene were designed for the camouflaging purpose, acoustic metamaterials were not used. The metastructures (source-shifters) were expressed at the design […]
Eruption of Tonga underwater volcano found to disrupt satellite signals halfway around the world
Phys.org May 22, 2023 Equatorial plasma bubbles which impact satellite-based communications was observed in the Asia-Pacific region after the eruption of the Tonga volcano on January 15, 2022. Researchers in Japan used satellite and ground-based ionospheric observations to demonstrate that an air pressure wave triggered by the Tonga volcanic eruption could cause the emergence of an equatorial plasma bubble. The most prominent observation result showed a sudden increase of electron density and height of the ionosphere several ten minutes to hours before the initial arrival of the air pressure wave in the lower atmosphere. They also found that the propagation […]
High-quality 2D films could be one-drop away
EurekAlert May 19, 2023 The effective application of 2D materials is strongly dependent on the mass production of high-quality large area 2D thin films. Researchers in Japan demonstrated a strategy for the automated manufacturing of high-quality 2D thin films using a modified drop-casting approach. They used an automated pipette to drop a dilute aqueous suspension onto a substrate heated on a hotplate, and controlled convection. Liquid removal caused the nanosheets to come together to form a tile-like monolayer film in 1–2 min. Ti0.87O2 nanosheets were utilized as a model system for investigating the control parameters such as concentrations, suction speeds, […]
Improving alloys: Researchers successfully establish a strong mechanical bond of immiscible iron and magnesium
Phys.org April 17, 2023 Steel is heavy, and scientists are turning to alternatives in the quest to improve the safety and speed of transportation, while simultaneously lessening its environmental footprint. Joining of Mg alloy to steel has received wide attention for design of multi-materials. Researchers in Japan have described joining of immiscible pure iron and pure magnesium (Fe–Mg), as a simplified model, performed by solid metal dealloying (SMD) between Mg and Fe100−xNix interlayers that were preliminary joined to the Fe part by diffusion bonding. SMD formed an Fe–Mg bicontinuous composite with interconnected morphology at the Fe–Mg weld interface. The effect […]
Storing information with spins: Creating new structured spin states with spatially structured polarized light
Phys.org March 27, 2023 So far, only uniformly polarized light has been exploited to control electron spins. However, if the polarization has an additional spatial structure it can produce spatially structured electron spins, opening up new ways to store information. Researchers in Japan devised a method for generating spatially structured electron spins using a structured light with spatially varying polarization profile. They transferred spatially variant polarization of topologically structured light to the spatial spin texture in a semiconductor quantum well. The electron spin texture was directly excited by a vector vortex beam with a spatial helicity structure. The spin texture […]