Impact of human capital and social capital on employability of Chinese college students under COVID-19 epidemic-Joint moderating effects of perception reduction of employment opportunities and future career clarity.

This research constructed a relationship model between human capital, social capital, and the employability of college students. With two moderating variables introduced, the perception reduction of employment opportunities under the COVID-19 epidemic and future career clarity, this research studied the direct impact of human capital and social capital on the employability of college students and boundary conditions. Research data from 810 employed Chinese college graduates shows that both human capital and social capital have a positive and significant impact on the employability; the perception reduction of employment opportunities under the COVID-19 epidemic negatively regulates the relationship between human capital and the employability of college students; the future career clarity positively regulates the relationship between human capital and the employability of college students; the perception reduction of employment opportunities under COVID-19 epidemic and the future career clarity jointly regulate the relationship between human capital, social capital and the employability of college students. These conclusions enrich the relevant theoretical and practical research on the employability of college students under the COVID-19 epidemic.

Preparation of nanometer powders of dental alumina ceramics / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to explore the preparation method of nanometer powders of dental alumina ceramics.</p><p><b>METHODS</b>The effects of concentration of inorganic precursors, pH value, calcination temperature and ageing time on the synthesizing process, phase composition and microstructure of the materials were studied. Aluminium nitrate with concentrations of 0.03 mol/L, 0.05 mol/L, 0.1 mol/L and 0.2 mol/L were used as inorganic precursors to prepare alumina powders via sol-gel method. Ammonia water was added into the solutions to adjust the pH values to 5, 9 and 11. The dried gel was then calcined under different temperatures, from 950 degrees C to 1200 degrees C. The prepared alumina powders were studied by using X-ray diffraction (XRD), and scanning electron microscope (SEM).</p><p><b>RESULTS</b>The alumina powder which was prepared with 0.1 mol/L aluminium nitrate, pH 9, and calcined at 1200 degrees C for 10 min showed good physical characteristics. The diameter of final powder was about 70 nm.</p><p><b>CONCLUSION</b>With the proper preparation condition, weakly agglomerated powders of alumina in nanometer particle size could be obtained.</p>

Preparation of nanometer powder of dental zirconia ceramics / 实用口腔医学杂志

?Objective: To study the preparation method of nanometer powder of zirconia, which was used to toughen dental alumina ceramics. Methods: The inorganic precursors at the concentrations of 0.0155 , 0.03, 0.05, 0.1 and 0.28 mol/L were used to prepare zirconia powder via precipitation method. Ammonia water was added into the said solutions to control the pH value at 7.0, 8.5 and 9. The dried precipitation product was then calcined. The prepared zirconia powder were studied by using X ray diffraction (XRD) and scanning electron microscope (SEM). Results: The zirconia powder prepared under the condition of 0.03 0.05 mol/L concentration of inorganic precursors, pH = 8.5, and calcined at 700 ℃ for 2 h was even in size,well dispersed and well micronized. The diameter of the final powder was about 100 nm. Conclusion: With proper preparation condition, weakly agglomerated powder of zirconia in nanometer size can be obtained.