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Compact CubeSat Gamma-ray detector for GRID mission
No full textGamma-Ray Integrated Detectors (GRID) mission is a student project designed to use multiple gamma-ray detectors carried by nanosatellites (CubeSats), forming a full-time all-sky gamma-ray detection network that monitors the transient gamma-ray sky in the multi-messenger astronomy era. A compact CubeSat gamma-ray detector, including its hardware and firmware, was designed and implemented for the mission. The detector employs four Gd2Al2Ga3O12 : Ce (GAGG:Ce) scintillators coupled with four silicon photomultiplier (SiPM) arrays to achieve a high gamma-ray detection efficiency between 10 keV and 2 MeV with low power and small dimensions. The first detector designed by the undergraduate student team onboard a commercial CubeSat was launched into a Sun-synchronous orbit on October 29, 2018. The detector was in a normal observation state and accumulated data for approximately one month after on-orbit functional and performance tests, which were conducted in 2019
Dissociate transfer exchange of tandem dynamic bonds endows covalent adaptable networks with fast reprocessability and high performance
No full textDevelopment of covalent adaptable networks (CANs) has connected thermosets and thermoplastics and brought about various functions. However, combining the high performance of thermosets and fast reprocessability of thermoplastics is still a challenge for CANs. Herein, we proposed a strategy of dissociate transfer exchange (DTE) of tandem dynamic bonds to achieve continuous reprocessability for CANs without compromising thermal and mechanical properties. Epoxy monomers with tandem imine and disulfide bonds were synthesized and cross-linked to produce CANs. The dissociation of disulfide bonds significantly increased the mobility of imine bonds in series with the breaking points, leading to a fast exchange rate and reprocessability and the high cross-link density and rigidity of the network provided good thermal and mechanical properties. We anticipate that this strategy can efficiently accelerate various functions such as shape-shifting and self-healing as well as reprocessing and welding and should be universally applied to other tandem dynamic systems
Fabrication of Porous Aluminum Coating by Cored Wire Arc Spray for Anchoring Antifouling Hydrogel Layer
No full textBiofouling has been persisting as a worldwide problem due to the difficulties in finding efficient environment-friendly antifouling coatings for long-term applications. Developing novel coatings with desired antifouling properties has been one of the research goals for surface coating community. Recently hydrogel coating was proposed to serve as antifouling layer, for it offers the advantages of the ease of incorporating green biocides, and resisting attachment of microorganisms by its soft surface. Yet poor adhesion of the hydrogel on steel surfaces is a big concern. In this study, porous matrix aluminum coatings were fabricated by cored wire arc spray, and the sizes of the pores in the aluminum (Al) coatings were controlled by altering the size of the cored powder of sodium chloride. Silicone hydrogel was further deposited on the porous coating. The hydrogel penetrated into the open pores of the porous Al coatings, and the porous Al structure significantly enhanced the adhesion of the hydrogel. In addition, hydrogel coating exhibited very encouraging antifouling properties
Effect of Si/B ratio on magnetic properties and microstructure of FeSiBNbCuAl nanocrystalline alloys
No full textThe effect of Si/B ratio on the magnetic properties, microstructure, magnetic domain structure, and crystallization kinetics of Fe77Si10+xB9-xNb2Cu1Al1 (x=0, 1, 2 at%) nanocrystalline alloys has been investigated. The slight increase in Si/B ratio has minimal effect on the saturation magnetization of the alloys, but effectively increases the permeability and decreases the coercivity in a wide annealing temperature range. Substituting 2% Si for B significantly increases the activation energy of alpha-Fe(Si) growth and Fe3B precipitation, leading to the formation of uniform, fine and stable alpha-Fe(Si) grains. This structure is beneficial to reduce the magnetocrystalline anisotropy and magnetoelastic anisotropy of the alloy, and form wide and smooth-moving magnetic domains, thus significantly improving the soft magnetic properties
Construction of hierarchical Prussian blue microcrystal with high sunlight absorption for efficient photo-thermal degradation of organic pollutants
No full textSolar-driven photocatalysis is considered to be a green and efficient approach for organic pollutants removal, however improving solar utilization and conversion still faces great challenge. Herein, Prussian blue (PB) microcrystals with different morphologies including PB-cube, PB-flower and PB-ball are fabricated via a secondaryassembly strategy. PB-ball with hierarchical structure possesses more exposed crystal faces, more mesopores, and higher FeII content, rendering its higher catalytic efficiency for organic pollutants degradation. Besides, structured hierarchical morphology leads to higher and broader sunlight absorption, which efficiently improves photo-Fenton performance of PBs due to the higher photon utilization. More importantly, we demonstrate that PBs with photothermal conversion property largely promotes its Fenton reaction rate under solar irradiation, and PBs as nano heat source in the photothermal Fenton system can accelerate the substance diffusion, charge carrier movement, as well as active radical generation. Thus, coupling of photo-Fenton and photothermal of dualfunction catalyst is an appealing strategy for organic pollutants removal
Ultrathin, flexible, and high-strength Ni/Cu/metallic glass/Cu/Ni composite with alternate magneto-electric structures for electromagnetic shielding
No full textElectromagnetic interference (EMI) shielding materials with ultrathin, flexible, superior mechanical and thermal management properties are highly desirable for smart and wearable electronics. Here, ultrathin and flexible Ni/Cu/metallic glass/Cu/Ni (Ni/Cu/MG) multilayer composite with alternate magnetic and electrical structures was designed via facial electroless plating of Cu and Ni on an Fe-based metallic glass. The resultant 0.02 mm-thick Ni/Cu/MG composite displays a superior EMI shielding effectiveness (EMI SE) of 35 dB and a great EMI SE/t of 1750 dB/mm, which is greater than those of composites with monotonous multilayer or homogeneous structures. The improved EMI SE originates from the massive ohmic losses, the enhanced internal reflection/absorption, and the abundant interfacial polarization loss. Particularly, Ni/Cu/MG exhibits a high tensile strength of up to 1.2 GPa and outstanding mechanical stability, enabling the EMI SE remains unchanged after 10,000 times of bending. Moreover, Ni/Cu/MG has excellent Joule heating characteristics and thermal stability, which is very suitable for heating components of wearable hyperthermia devices. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology
