Purpose The COVID-19 pandemic has adversely impacted the mental health of the population. The current study aimed to determine the prevalence of depressive symptoms and sleep disturbances among Chinese college students during the COVID-19 pandemic and investigate the correlations between chronotypes, sleep quality, and depressive symptoms. Participants and Methods In the current study, 2526 college students responded anonymously to an online questionnaire survey from 26 May 2020 to 20 July 2020. The participants’ chronotypes, sleep quality, and depressive symptoms were evaluated using the Chinese version of the Morning and Evening Questionnaire-5 (MEQ-5), Pittsburgh Sleep Quality Index (PSQI), and Patient Health Questionnaire-9 (PHQ-9). Sociodemographic information of the participants was also acquired. Statistical analyses were performed using Statistical Package for Social Sciences (SPSS) 19.0 software, with the mediating effect assessed by Hayes’ PROCESS Macro. Results During the COVID-19 pandemic, the prevalence of depressive symptoms and sleep disturbances among Chinese college students surveyed was 54.95% and 48.18%, respectively. From absolute evening chronotype to absolute morning chronotype, the surveyed college students’ chronotypes were negatively correlated with their depressive symptoms. Moreover, the mediation analysis showed that the correlation between chronotypes and depressive symptoms was fully mediated by sleep quality. Eveningness college students with poorer sleep quality were more likely to report higher levels of depressive symptoms. Conclusion Our findings suggest that during the COVID-19 pandemic, delayed circadian preference (ie, eveningness) may be linked to worse depressive symptoms among Chinese college students, and call for more attention to the sleep quality of Chinese college students as sleep quality fully mediated the correlation between chronotypes and depressive symptoms among them. Reasonable adjustment in bedtime/circadian preference and improvement in sleep quality may help to reduce the prevalence and severity of depressive symptoms among Chinese college students.

No abstract

The stent is commonly used to support blood vessels to avoid blood obstruction. Its tubular structure is a combination of micro periodic structures. The stent is expanded uniformly due to its internal pressure during the implantation process until plastic deformation occurs. In this article, the simulation of a representative model with application of the proposed periodic boundary conditions is performed by using ABAQUS/Explicit package and Matlab code. To make a comparison, the entire model of the same type stent with general boundary condition is also analyzed. The numerical results show that the deformation and stress distribution calculated by the representative model is a little higher than those of the entire model, but their overall results agree well with each other. Therefore, the numerical results of the entire stent can be obtained by a simple geometrical tessellation of the deformed representative models. The advantage of this method is that it can significantly reduce the modeling and computing time for analyzing expansion of vessel stent.

The erythrocytes play an important role in delivering oxygen and carbon dioxide in the human body. They are generally believed to be highly deformable and are able to squeeze through small capillaries. The elastic rigidity of the cell is associated to the change in free energy caused by both the stretch and the bending of the erythrocyte membrane. If the curvature of a shell is changed by deformation, the bending stiffness must be considered. However, researchers usually focus on the stretch of the cell membrane while analyzing the experimental data. In this article, mechanical models were proposed to study the erythrocytes deformation during optical tweezers stretching and micropipette aspiration. The effect of membrane bending stiffness on the cells deformability was concluded using finite element modeling and simulation.

A highly automated way for serial data validation is presented in this paper. The method is based on widely available Digital Storage Oscilloscope (DSO) and low cost Personal Computer (PC). Instrument automation with data capturing and processing is demonstrated. The method is able to process large amount of high speed serial data. The validation procedure is shown in this paper; two instrument automation control protocols are described; data processing algorithm in Python language is also discussed.