Search

Based on the typical dielectric materials and devices of satellite, a surface charging and dose monitor (SCAD) was developed to measure the surface charging voltage, current, and dose under different shielding depths. The SCAD has been successfully launched into orbit on June 23, 2020. The measurement results on orbit show that the SCAD works normally, and the data of SCAD are reasonable. The results show that the radiation dose rate on geosynchronous orbit is about 0.4 mrad(Si)/s, and the maximum charging voltage is about −800 V during the initial measuring period. The charging voltage is consistent with the trends of geomagnetic disturbance Kp index. The on-orbit data provide basic data on surface charging and discharging effect and total dose effect, supporting the safe and reliable operation of the satellite.

Combining the anomalies and environmental monitoring data of the early stage Beidou satellites, the space radiation environment spatial/temporal distribution and space radiation effect risk characteristics are analyzed, and the dynamic characteristics of space environmental factors, such as hot plasma, high-energy electron and solar proton are summarized. The systematic joint monitoring for surface charging, internal charging, single event effect and total dose effect with corresponding space environment factors is proposed. The detector types, measurement parameters range and engineering constraints are allocated, and the engineering application and scientific research of detection data are prospected.

Single event upset (SEU) has always been an important factor affecting the reliability of spacecraft electronic equipment, which can cause anomalies in electronic equipment in orbit, and can result in serious spacecraft failure. In order to master signal event upset discriminating and positioning technology, and to study the mechanism between SEU physical position and particle energy, a technology method about SEU discriminating and positioning was proposed in this paper, and the principle prototype system was developed. The principle prototype system consists of silicon detector and electronics module. The silicon detector and the irradiation�sensitive device are mounted in close proximity to each other in the vertical direction, and the position region where the particles are incident to the silicon detector corresponds to the physical position of the logical upset of the target device. On the one hand, the silicon detector is divided into an array grid, electronics module includes multiple detection channels, and high�energy particles hitting a grid position of the silicon detector can be detected. On the other hand, the logical position of the target device where a single particle upset occurs can be detected by the circuit. Position sensitive detector is a silicon PIN type semiconductor particle detector dividing into a 4×4 array grid corresponding to each of the 16 measurement channels. Each grid is 4�5 mm wide square with a thickness of 300 μm. The silicon detector is packaged on a PCB board, where the detector grids are connected to the pads of the PCB by gold wire crimping. The electronics module mainly includes pre�amplifier circuit, main amplifier and signal conditioning circuit, multichannel waveform signal peak�seeking circuit, particle�triggered circuit, SEU logic detection circuit for SRAM devices, FPGA control and communication circuit, etc. Waveform digitization technology is adopted, particle waveform peak value and particle arrival time are obtained through high speed analog�to�digital conversion and digital signal acquisition and processing. The basic method of SEU detection circuit for SRAM is the data read�back comparison method, the FPGA writes a cyclically accumulating 8�bit number to the address range of the SRAM at the maximum rate of the SRAM read/write, then reads it out of the SRAM and compares it with the written data for the difference. If the result is “1”, it means that a SEU event has occurred; if “0” appears, it proves that no SEU has occurred. According to the results of laboratory test and single�particle irradiation test, the LET of detectable energetic particle is greater than 6�06×10-3 MeV·cm2/mg, the position resolution of incident particles is better than 5 mm, the maximum count rate is more than 104 s-1, and the SEU inspection cycle time resolution of SRAM devices is 13�76 ms. By mastering the SEU discriminating and positioning of large�capacity SRAM device and the radiation environment sensing capability, it can improve the performance of space electronics in orbit. By mastering the single�particle flip screening and positioning of the large�capacity SRAM devices and their radiation environment sensing capability, it can improve the on�orbit performance of space electronics.

Macroautophagy/autophagy plays a crucial role in inhibiting viral replication and regulating the host’s immune response. The autophagy receptor SQSTM1/p62 (sequestosome 1) restricts viral replication by directing specific viral proteins to phagophores for degradation. In this study, we investigate the reciprocal relationship between Zika virus (ZIKV) and selective autophagy mediated by SQSTM1/p62. We show that NS2B3 protease encoded by ZIKV cleaves human SQSTM1/p62 at arginine 265 (R265). This cleavage also occurs with endogenous SQSTM1 in ZIKV-infected cells. Furthermore, overexpression of SQSTM1 inhibits ZIKV replication in A549 cells, while its absence increases viral titer. We have also shown that SQSTM1 impedes ZIKV replication by interacting with NS3 and NS5 and directing them to autophagic degradation, and that NS2B3-mediated cleavage could potentially alter this antiviral function of SQSTM1. Taken together, our study highlights the role of SQSTM1-mediated selective autophagy in the host’s antiviral defense against ZIKV and uncovers potential viral evasion strategies that exploit the host’s autophagic machinery to ensure successful infection.Abbreviation: Cas9: CRISPR-associated protein 9; Co-IP: co-immunoprecipitation; CRISPR: clustered regularly interspaced short palindromic repeats; DENV: dengue virus; GFP: green fluorescent protein; IFA: indirect immunofluorescence assay; KIR: KEAP1-interacting region; KO: knockout; LIR: MAP1LC3/LC3-interacting region; mAb: monoclonal antibody; NBR1: NBR1 autophagy cargo receptor; OPTN: optineurin; pAb: polyclonal antibody; PB1: Phox/BEM1 domain; R265A, a SQSTM1 construct with the arginine (R) residue at position 265 replaced with glutamic acid (A); SQSTM1: sequestosome 1; SQSTM1-C, C-terminal fragment of SQSTM1; SQSTM1-N, N-terminal fragment of SQSTM1; SVV: Seneca Valley virus; TAX1BP1: Tax1 binding protein 1; TBD: TRAF6-binding domain; TCID50: 50% tissue culture infective dose; UBA: ubiquitin-associated domain; Ub: ubiquitin; WT: wild type; ZIKV: Zika virus; ZZ: ZZ-type zinc finger domain. [ABSTRACT FROM AUTHOR]

Surgical treatment of vertigo is performed with in-depth study of inner ear diseases. Achieving an effective control of vertigo symptoms while reducing damage to hearing and reducing surgical complications is the principle followed by scholars studying surgical modalities. Semicircular canal occlusion is aimed at treatment of partial peripheral vertigo disease and has attracted the attention of scholars because of the above advantages. This article provides a review of the origins of semicircular canal occlusion, related basic research, clinical applications, and the effects of surgery on vestibular and hearing function.

Addressing the demand for integrating strength and durability reinforcement in shape memory polyurethane (SMPU) for diverse applications remains a significant challenge. Here a series of SMPUs with ultra‐high strength, self‐healing and recyclability, and excellent shape memory properties through introducing dynamic boron–urethane bonds are synthesized. The introducing of boric acid (BA) to polyurethane leading to the formation of dynamic covalent bonds (DCB) boron–urethane, that confer a robust cross‐linking structure on the SMPUs led to the formation of ordered stable hydrogen‐bonding network within the SMPUs. The flexible crosslinking with DCB represents a novel strategy for balancing the trade‐off between strength and durability, with their strengths reaching up to 82.2 MPa while also addressing the issue of durability in prolonged usage through the provision of self‐healing and recyclability. The self‐healing and recyclability of SMPU are demonstrated through rapid dynamic exchange reaction of boron–urethane bonds, systematically investigated by dynamic mechanical analysis (DMA). This study sheds light on the essential role of such PU with self‐healing and recyclability, contributing to the extension of the PU's service life. The findings of this work provide a general strategy for overcoming traditional trade‐offs in preparing SMPUs with both high strength and good durability. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) materials with high strength, toughness, anti‐wear properties, and high heat resistance are in high demand for dynamic sealing applications. In this study, a series of high‐performance crosslinking polyurethanes (CPUs) were prepared by pre‐polymerization of polycarbonate diol (PCDL) with toluene‐2,4‐diisocyanate (TDI), followed by crosslinking with trimethylolpropane (TMP). The molar ratio (R) of PCDL/ TDI and the degree of cross‐linking were found to significantly affect the microphase separation. The results indicate that as the R‐value increases, the transition temperature of CPUs increases from 6.0°C to 82.4°C, and the tensile strength increases from 21.1 ± 2.5 MPa to 46.0 ± 3.6 MPa. Moreover, the CPUs exhibit excellent heat resistance (with a heat resistance index of ~150°C) and hydrolysis resistance, attributed to the high crystallinity of PCDL and the synergistic effect of chemical crosslinking. Additionally, the CPUs demonstrate low friction coefficient (COF = 0.01–0.062), exceptional anti‐wear properties (Akron wear, 0.11–0.07 cm3/1.61 km), and outstanding fatigue resistance. These desirable characteristics make CPUs suitable for use as dynamic sealing or lubricating materials in harsh conditions, thereby extending the service life of seals and preventing leakage and other related issues. [ABSTRACT FROM AUTHOR]