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The Al-Mg-Si alloy plate produced by traditional hot rolling has many defects such as complicated processes， long time and high cost， which seriously restricts the development of Al-Mg-Si alloy. Therefore， the Al-Mg-Si alloy plate produced by the twin-rolling casting process has attracted great attention in recent years. The twin-rolling casting process was used to prepare the Al-Mg-Si aluminum alloy plate， and the difference of microstructure at different positions of the plate and the influence on the performance were investigated. The results show that the grain morphology of the edge and the center of the plate is significantly different， the texture composition is complex， a large number of second phases are unevenly distributed along the grain boundary， and there is obvious element segregation inside the plate. According to the theoretical calculation， the contribution strength of texture strengthening at the edges of the twin-rolling casting plate is 10.7 MPa and the contribution strength of grain boundary strengthening is 86.8 MPa， while the contribution strength of texture strengthening in the center of the twin-rolling casting plate is 15.1 MPa and the contribution strength of grain boundary strengthening is 82.4 MPa. The contribution of plate texture and random texture to the strength is limited， and the strength difference between edge and center mainly depends on the grain boundary strengthening. Different degrees of dislocation tangles exist at the edge and the center， and the dislocation density at the edge is higher than that at the center， which is consistent with the statistical results of low angle grain boundaries. According to the characteristics of microstructure inhomogeneity of the plate， the theoretical guidance for the subsequent heat treatment system of the plate is provided through thermodynamic calculation.

ObjectiveThe current study aims to investigate the correlations between qi stagnation, qi deficiency, and depression levels among college students.MethodThis study investigated 403 college students and measured their levels of depression, qi stagnation, and qi deficiency to analyze the relationship between these three variables. Pearson correlation and linear regression statistical techniques were utilized.Results(1) On average, college students reported mild depressive symptoms; (2) college students manifested low levels of qi stagnation and qi deficiency. (3) There exists a strong positive correlation between qi stagnation and qi deficiency; (4) a moderate positive correlation is present between depression and both qi stagnation and qi deficiency among college students. All these results support the mechanism by which qi stagnation and qi deficiency contribute to depression in traditional Chinese medicine theory.ConclusionQi stagnation and qi deficiency are moderately associated with depression levels in college students. It is feasible to use traditional Chinese physical therapy for qi regulation to alleviate depressive symptoms among college students.

The compression deformation test on extruded-solid solution 7A43 alloy (Al-6.0Zn-2.1Mg-0.15Cu-0.15Zr, mass fraction/%) was conducted by Gleeble-3500 machine with strain rate of 0.001 s-1 to 1 s-1 at room temperature, and the microstructural features were characterized by scanning electron microscopy (SEM), backscattered electron microscopy (EBSD) and X-ray differaction analysis (XRD). It is revealed that with the increase of strain rate, the average grain size decreases due to severe microstructural distortion, whilst the lattice strain and dislocation density in the alloy gradually increase. Dynamic recovery substructure components in the microstructure are enhanced, and the coarse deformed grains are replaced by fine equiaxed grains under high deformation rate conditions. A Fields-Backofen (F-B) constitutive model was constructed based on the experimental stress-strain data, the correlation coefficient (R) and average absolute relative error (AARE) between the experimental and predicted values are 0.991069 and 3.667%, respectively, which provide a good description of the model for deformation rheological behavior of 7A43 aluminum alloy at room temperature.

In order to study the changes in the content, type of the refractory phases and grain size during homogenization of the 5083 aluminum alloy, material microstructure was characterized by metallographic microscope (OM), scanning electron microscope(SEM), energy dispersive spectrometer(EDS), differential scanning calorimetry (DSC) and X-ray diffractometer (XRD). The results show that the refractory phases in the cast 5083 aluminum alloy are composed of Al(FeMnCr) phases, Al(FeMnCr)Si phases and Mg2Si phases. The composition of the cast state alloy was verified by using phase diagram calculations, and the results are basically consistent with the experiment. As the temperature rises from 460 ℃ to 560 ℃, the electrical conductivity increases firstly and then decreases. This is related to the precipitation of dispersed phase and the dissolution of refractory phase in the structure. When the homogenization processing is 540 ℃/10 h and 560 ℃/10 h, the refractory phase is dominated by the needle-flake Al(FeMnCr) phases, Mg2Si phases is fully solubilized, the area fractions are 0.730% and 0.632%, respectively, and there is no over burned tissue at the same time, and there are obvious dispersed phase particles in the grain. Therefore, to dissolve part of the refractory phases in cast 5083 aluminum alloy, the homogenization temperature must be ≥540 ℃. Increasing homogenization temperature and prolonging homogenization time will increase grain size.When the homogenization temperature is less than 540 ℃, the insoluble phase changes have little effect on the grain growth, when the homogenization temperature is greater than 540 ℃, the average grain size begins to be greater than 140 μm, and the refractory phase is dissolved at the same time.

For this article, hot compression tests were carried out on homogenized 2050 Al-Cu-Li alloys under different deformation temperatures and strain rates, and an Arrhenius-type constitutive model with strain compensation was established to accurately describe the alloy flow behavior. Furthermore, thermal processing maps were created and the deformation mechanisms in different working regions were revealed by microstructural characterization. The results showed that most of the deformed grains orientated toward <101>//CD (CD: compression direction) during the hot compression process, and, together with some dynamic recovery (DRV), dynamic recrystallization (DRX) occurred. The appearance of large-scale DRX grains at low temperatures rather than in high-temperature conditions is related to the particle-stimulated nucleation mechanism, due to the dynamic precipitation that occurs during the deformation process. The hot-working diagrams with a true strain of 0.8 indicated that the high strain-rate regions C (300 °C–400 °C, 0.1–1 s−1) and D (440 °C–500 °C, 0.1–1 s−1) are unfavorable for the processing of 2050 Al-Li alloys, owing to the flow instability caused by local deformation banding, microcracks, and micro-voids. The optimum processing region was considered to be 430 °C–500 °C and 0.1 s−1–0.001 s−1, with a dissipation efficiency of more than 30%, dominated by DRV and DRX; the DRX mechanisms are DDRX and CDRX. [ABSTRACT FROM AUTHOR]

A noisy environment can considerably impact drivers' attention and fatigue, endangering driving safety. Consequently, this study designed a simulated driving experimental scenario to analyse the effects of noise generated during urban rail transit train operation on drivers' functional brain networks. The experiment recruited 16 participants, and the simulated driving scenario was conducted at noise levels of 50, 60, 70, and 80 dB. Functional connectivity between all electrode pairs across various frequency bands was evaluated using the weighted phase lag index (WPLI), and a brain network based on this was constructed. Graph theoretic analysis employed network global efficiency, degree, and clustering coefficient as metrics. Significant increases in the WPLI values of theta and alpha frequency bands were observed in high noise environments (70 dB, 80 dB), as well as enhanced brain synchronisation. Furthermore, concerning the topological metrics of brain networks, it was observed that the global efficiency of brain networks in theta and alpha frequency ranges, as well as the node degree and clustering coefficients, experienced substantial growth in high noise environments (70 dB, 80 dB) as opposed to 50 dB and 60 dB. This finding indicates that high-noise environments impact the reorganisation of functional brain networks, leading to a preference for network structures with improved global efficiency. Such findings may improve our understanding of the neural mechanisms of driving under noise exposure, and thus potentially reduce road accidents to some extent. [ABSTRACT FROM AUTHOR]