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Objective To investigate the training, career development and mental status of anesthesia postgraduates during the pandemic of COVID-19. Methods A self-designed questionnaire was distributed through WeChat platform to anesthesia postgraduates in Beijing, Shanghai and Chengdu. The data were recorded automatically. Results A total of 222 anesthesia postgraduates participated in the survey. Among them, 52.7% of the students were contented with outcomes of online learning, 37.84% of the students considered their graduation were negatively affected by the pandemic, 76.92% of the students thought they were more used to interview in real life than online interview, and 54.95% of the students had psychological counseling service provided by school experts during the pandemic. Conclusions During the COVID-19 pandemic, medical school endeavored to guarantee the study, career development and mental health of postgraduates.

The T700/HT280 composites were subjected to vacuum thermal cycling (-140-180℃,10-3 Pa). The mass loss rate, dynamic mechanical properties and low-speed impact of composites were tested before and after vacuum thermal cycling respectively. The visual observation, ultrasonic C-scan and finite element (FE) analysis were used to analyze, characterize and simulate the low-speed impact damage. The results show that the mass loss rates of T700/HT280 composites and matrix resin are increased rapidly and then level off with the increase of the number of vacuum thermal cycles, which is due to the gassing effect. After the vacuum thermal cycle treatment, T700/HT280 composites show some degree of post-cure, thermal aging and partial interface debonding. The main damage mode at low impact energy is that the matrix resin is compressed. However, matrix cracking and delamination are deemed as the damage mode at high impact energy. The FE simulation results are consistent with the experimental results. As the impact energy increases, the absorption energy of the composites is increased. Under the condition of 30-40 J impact energy, the absorption energy can effectively characterize the environmental damage effects of vacuum thermal cycle on composites.

Sulfur plays a vital role in the phytoremediation of lead-contaminated soil. The effects of different sulfur forms (S Na2S, and Na2SO4) on lead (Pb) absorption in hyperaccumulator Arabis alpina L. var. parviflora Franch were studied in a soil pot experiment. The subcellular sulfur and lead enrichment characteristics in A. alpina were studied by adding sulfur in different forms and concentrations (0, 75, and 150 mg·kg−1) to Pb-contaminated soil. The results show that the root and shoot biomass increased by 1.94 times under Na2S and Na2SO4 treatment, and the root–shoot ratio of A. alpina increased 1.62 times under the three forms of sulfur treatments, compared with the control. Sulfur content in cell walls and soluble fractions of the root and shoot of A. alpina significantly increased 3.35~5.75 times and decreased 5.85 and 9.28 times in the organelles under 150 mg·kg−1 Na2SO4 treatment. Meanwhile, Pb content in the root and shoot cell walls of A. alpina significantly increased by 3.54 and 2.75 times, respectively. Pb content in the shoot soluble fraction increased by 3.46 times, while it significantly reduced by 3.78 times in the shoot organelle. Pb content in the root organelle and soluble fraction decreased by 2.72 and 2.46 times. Different forms and concentrations of sulfur had no regularity in the effect of Pb and sulfur content in the subcellular components of A. alpina, but the bioconcentration and translocation factors of A. alpina increased compared with the control. Under different concentrations of Na2SO4, there was a significant positive correlation between the contents of sulfur and Pb in the subcellular components of the root of A. alpina (p < 0.05). These results indicate that sulfur application can enhance the Pb resistance of A. alpina by strengthening the cell wall fixation and vacuolar compartmentalization.

The measurement of the pole axis deviation angle of superconducting magnetic levitation rotors plays a crucial role in the field of high-precision navigation. This article conducts theoretical analysis and experimental research on the diffuse reflection intensity modulation principle of optical fiber sensors and the ideal diffuse reflection modulation model under ideal conditions. First, the structural distribution of optical fiber sensors is presented, and the principle of measuring the polar deviation angle of superconducting magnetic levitation rotors is analyzed. Then, based on the diffuse reflection intensity modulation principle, an optical fiber intensity modulation model for ideal superconducting magnetic levitation rotors is established. The correctness of this model was verified through simulation and calibration experiments, and the error between the simulation and experimental results was less than 8%. [ABSTRACT FROM AUTHOR]

The enhancement of chopped fiber as a reinforcing agent on the welding interface of composite materials was explored. Glass fiber reinforced polyetherimide (GF/PEI) laminate was joined using the pulse resistance welding technology, using a stainless steel (SS) mesh as the heating element. A single lap shear test was performed on the weldments of aramid fiber (AF), glass fiber (GF), and carbon fiber (CF) as reinforcing agents to evaluate the strength of the welded joint. The results show that the fiber achieves the welding interface strengthening by cooperating with the SS mesh heating element to contribute to the mechanical properties of the welded joint. Fracture analysis shows that under the reinforcement of fiber, the main failure mode in the initial stage of welding is fiber and matrix debonding. When the strength of the weldment achieves the best, the failure mode is changed into the simultaneous tearing of SS mesh heating element and fiber tear.

The material behavior of glass fiber reinforced aluminum laminates (GLARE) under low-speed impact of a falling hammer was studied, and a finite element model of ABAQUS for simulation and experimental verification was built. According to the characteristics of fiber metal matrix materials, the continuous damage mechanics (CDM) model was adopted, and the impact energy values of the falling hammer were set as 6.22 J, 12.38 J and 14.46 J respectively. The corresponding boundary conditions and loads of the model in ABAQUS were confirmed to obtain the velocity-time curve and energy loss curve of the falling direction of the falling hammer. The cohesive layer between metal layer and composite layer was taken into consideration, and the ‘Cohesive Layer’ in ABAQUS was adopted to bond metal layer and composite material layer. The tensile and compressive damage states of fibers and matrix in simulation were observed and compared with the experimental results. The results show that the finite element simulation can accurately simulate the crack and bulge effect on the back of GLARE laminates after the impact, as well as the damage situation of the matrix and fiber, so as to well predict the internal damage of the composite material.

Abstract Background Many tripartite motif (TRIM) family proteins have been reported to be of great importance in the initiation and progression in hepatocellular carcinoma (HCC). However, the biological role and regulatory mechanism of tripartite motif containing 52 (TRIM52) in HCC development and progression are poorly defined. Methods Immunohistochemistry (IHC), quantitative real-time PCR (qRT-PCR) or Western blot analysis was used to detect TRIM52, p21, matrix metalloproteinase 2 (MMP2), protein phosphatase, Mg2+/Mn2+ dependent 1A (PPM1A), p-Smad2/3 and Smad2/3 levels in HCC tissues and cell lines. HCC cell proliferation and cell cycle were measured by Cell Counting Kit-8 (CCK-8) and flow cytometry analysis, respectively. HCC cell migration and invasion were measured by Transwell assay. Tumor growth of HCC cells in vivo was measured using the nude mouse xenograft model. The correlation between TRIM52 and PPM1A was measured by co-immunoprecipitation (Co-IP) and ubiquitination analysis in vitro. Results TRIM52 was significantly up-regulated in the HCC tissues in comparison with the adjacent non-tumor hepatic tissues. TRIM52 was also up-regulated in HCC cell lines (MHCC-97H and MHCC-97L cells) compared with normal human liver cell line LO2. TRIM52 down-regulation by RNA interfering in MHCC-97H cells enhanced inhibition of cell proliferation, migration and invasion. TRIM52 down-regulation also induced MHCC-97H cells arrest in G0-G1 phase cell cycle and inhibited MHCC-97H cell growth in the nude mice. However, TRIM52 up-regulation in MHCC-97L cells promoted cell proliferation, migration and invasion. Furthermore, TRIM52 down-regulation significantly increased p21 and PPM1A expression, but inhibited MMP2 expression and induced Smad2/3 dephosphorylation in MHCC-97H cells, which were reversed by TRIM52 up-regulation in MHCC-97L cells. TRIM52 was found interacted with PPM1A and TRIM52 down-regulation inhibited the ubiquitination of PPM1A. Importantly, PPM1A up-regulation in MHCC-97L cells significantly suppressed TRIM52-mediated enhancement on cell proliferation, invasion and migration. Conclusions Our findings suggest that TRIM52 up-regulation promotes proliferation, migration and invasion of HCC cells through the ubiquitination of PPM1A.