Nanowerk September 13, 2023 Nanomaterials usually fail to twist into helical crystals. Considering the irreversibility of the previously studied twisting forces, the reverse process (untwisting) and retwisting areas more difficult to achieve. Researchers in China have reported a new reciprocal effect between molecular geometry and crystal structure which triggered a twisting-untwisting-retwisting cycle for tri-cobalt salicylate hydroxide hexahydrate. The twisting force stemmed from competition between the condensation reaction and stacking process, different from the previously reported twisting mechanisms. The resulting distinct nanohelices gave rise to unusual structure elasticity, as reflected in the reversible change of crystal lattice parameters and the mutual […]
Tag Archives: S&T China
Team develops novel sponge-based triboelectric nanogenerator for corrosion protection in transportation systems
Phys.org September 5, 2023 Researchers in China demonstrated highly elastic, and pressure-resistance sponge fabricated TENG capable of adapting to high strength impact in land and water transportation and scalable for any shape for harvesting wave energy and mechanical energy. The sponge had interconnected network and large size ratio of cavity-wall suitable for contact and separation enabled higher output due to the combination of the electronegativity, adhesion, and antioxidant ability. The operation modes provided options for different operating condition and enabled higher output due to the combination of the electronegativity, excellent adhesion, and antioxidant ability… read more. TECHNICAL ARTICLE
New study reveals remarkable impact of intrinsic spin shielding in platinum-rare earth alloys on electrocatalysis
Phys.org July 24. 2023 Researchers in China introduced platinum–rare earth metal-based alloy catalyst, Pt2Gd, to reveal the role of spin configurations in the catalytic activity of materials. The catalyst exhibited a unique intrinsic spin reconfiguration because of interactions between the Gd-4f and Pt-5d orbitals. The adsorption and desorption of the oxygen species were optimized by modifying the spin symmetry and electronic structures of the material for increased oxygen reduction reaction (ORR) efficiency. The Pt2Gd alloy exhibited a half-wave potential, and a superior mass activity, and higher durability than conventional Pt/C catalysts. Theoretical calculations have proved that the spin shielding effect […]
China has begun launching its own satellite internet network
Phys.org July 17, 2023 On Sunday, July 9, launched a prototype internet satellite from China’s Jiuquan Satellite Launch Center in Inner Mongolia. The satellite will conduct several tests to validate the broadband satellite technology. The long-term aim of the project is to create a constellation of 13,000 satellites code-named “Guo Wang”. They intend to create two constellations (GW-A59 and GW-2) with a coverage of 37.5 to 42.5 GHz (space-to-Earth) and 47.2 to 51.4 GHz (Earth-to-space). According to multiple sources, this constellation is part of a wider effort by China to stake its claim to the growing satellite internet market. The […]
Shrinking light: Waveguiding scheme enables highly confined subnanometer optical fields
Phys.org July 17, 2023 Researchers in China developed an optical waveguide scheme to generate a sub-nanometer-confined optical field in a nano slit waveguiding mode in a coupled nanowire pair (CNP). They showed that, when a conventional waveguide mode with a proper polarization was evanescently coupled into a properly designed CNP with a central nano slit, it could be channeled into a high-purity nano slit mode within a waveguiding length <10 μm. The CNP could be either freestanding or on-chip by using a tapered fiber or planar waveguide for input-coupling, with a coupling efficiency up to 95%. Within the slit region, […]
Thermal cloak passively keeps electric vehicles cool in the summer and warm in the winter
Science Daily July 11, 2023 Despite intensive efforts invested, high-efficacy, all-season temperature regulation on real-world objects has not yet been achieved through truly passive, reliable structures. Researchers in China proposed and experimentally realized a Janus thermal cloak (JTC) composed of an all-ceramic, radiative-cooling phononic metafabric facing the sky and a photon-recycling foil facing indoor space. The phononic metafabric, which supports broadband hyperbolic phonon polaritons (HPhPs) and strong scattering of phonon transport, showed resilience under harsh thermal, mechanical, and corrosive environments. Field tests on electric vehicles showed that the JTC realized daytime sub-ambient cooling by 8.0°C in summer and nighttime supra-ambient […]
Exploring gravity’s effect on quantum spins
Phys.org June 16, 2023 Among the four fundamental forces, only gravity does not couple to particle spins according to the general theory of relativity. Researchers in China tested this principle by searching for an anomalous scalar coupling between the neutron spin and the Earth’s gravity on the ground. They developed an atomic gas comagnetometer to measure the ratio of nuclear spin-precession frequencies between 129Xe and 131Xe, and searched for a change of this ratio to the precision of 10−9 as the sensor is flipped in Earth’s gravitational field. The null results of this search set an upper limit on the […]
Researchers develop an extreme environment-resistant nanopaper
Phys.org June 21, 23 Researchers in China developed a kind of nacre-inspired bacterial cellulose (BC)/synthetic mica (S-Mica) nanopaper with excellent mechanical and electrical insulating properties that has excellent tolerance to extreme conditions. The nanopaper exhibited excellent mechanical properties, including high tensile strength (375 MPa), outstanding foldability, and bending fatigue resistance. S-Mica arranged in layers endowed the nanopaper with remarkable dielectric strength (145.7 kV mm−1) and ultralong corona resistance life. The nanopaper was highly resistant to alternating high and low temperatures, UV light, and atomic oxygen… read more. TECHNICAL ARTICLE
‘Heat highways’ could keep electronics cool
Science Daily June 6, 2023 Researchers in China constructed uniaxial-polyvinyl alcohol/nanodiamond (U-PVA/ND) and coaxial-polyvinyl alcohol/nanodiamond (C-PVA/ND) composite fiber films with different microscopic morphologies by uniaxial and coaxial electrospinning. The results showed that the thermal conductivities of U-PVA/ND and C-PVA/ND composite fibers with 60 wt % ND content are 71.3 and 85.3 W m–1 K–1, respectively, which were 171.2 and 205.1 times greater than that of the pure PVA fiber film. The maximum thermal decomposition temperature (Tmax) and volume resistivity of the C-PVA/ND composite fiber film were 364.3 °C and 2.29 × 1015 Ω·cm, respectively, demonstrating the excellent thermal stability and […]
Liquid metal sticks to surfaces without a binding agent
Science Daily June 9, 2023 Origami’s performance is limited by the properties of the constituent materials, including long-term bending, electrical, and thermal conductivity. Researchers in China reported a new method for directly adhering liquid metal onto non-wetting substrates on a large scale, allowing for the regulation of the mechanical and electrical properties of the enhanced paper by controlling the applied force during fabrication. The mechanism of adhesion between different liquid metals (eGaIn and BiInSn) and non-wetting substrates through force was explained. Multifunctional origami structures based on the enhanced paper could switch between several deformation modes and include a shape memory […]