Background: The aim of this study was to investigate the amount and sources of stress in dental undergraduate students in Fujian, China, and the factors associated with stress. Methods: This cross-sectional study was conducted during the second semester of the 2017-2018 academic year at the School of Stomatology, Fujian Medical University, China. A total of 396 students were surveyed with the Dental Environment Stress Questionnaire (DES) and the Perceived Stress Scale (PSS) using an online survey system. The participants' demographic information, including sex, age, year of study, and grade point average (GPA) was also collected. One-way analysis of variance (ANOVA) was performed to compare the stress scores. Pearson correlation and multiple linear regression analyses were conducted to explore the associated factors of stress and academic performance. All statistical analyses were performed at a significance level of 5%. Results: A total of 347 undergraduate students participated in the present study, for a response rate of 87.6%. There were no significant differences in the DES and PSS total scores among students of different grades and sexes. Significant differences were found in the DES "workload" and "self-efficacy beliefs" scores among students from different study years (all P < 0.05). The Multiple linear regression showed that DES and PSS scores were negatively correlated with GPA, while sex was positively correlated with GPA (all P < 0.05). Female students had significantly higher GPAs than male students. Conclusions: Dental undergraduates in Fujian, China experienced moderate levels of stress. While the amount of stress did not differ by year of study, the sources of stress did differ. Stress scores and sex were negatively correlated with academic performance.

The Bi2Ti4O11 nanorods were obtained by a one-step alcohol-thermal method. The sample was synthesized at 100°C and calcined at 600°C, using Bi(NO3)3•5H2O, TiCl4 and absolute ethanol as reactants. It then characterized by XRD, SEM and UV-vis DRS. The results showed that the sample was nanorod with diameter about 30nm and length about 200nm. The photocatalytic experiment represented that the photocatalyst could effectively degrade more than 99% Rhodamine B( RhB) within 85 min under irradiating of visible light.

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The numerical simulation of high-energy femtosecond laser ablation on metal target is studied in this paper. Based on the two-temperature model (TTM), a new model considering the effects of the electron density of states (DOS) on electronic heat capacity, electron-phonon coupling coefficient and electronic thermal conductivity is established. As an example of gold target, the relationship between the melting threshold and the thickness of gold films is numerically calculated. Our result is more consistent with the experimental datum in contrast to the results without considering the DOS effects. This shows that the revised TTM of high-energy femtosecond laser ablation (i.e. DOS-TTM) is more reasonable compared with general used TTM.

Single crystal rutile TiO2 microfibers have been synthesized by hydrothermal method using TiCl3 as titanium source. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) investigations reveal that the microfibers with average diameter of 15 μm and length of 1~2 mm are self-assembled by single crystal TiO2 nanorods and well-dispersed. The bandgap Eg of microfibers is about 3.0 eV by UV-vis adsorption spectrum.