Papers by Author: Yan Gang Zhao

Abstract: CdS nanocrystallites with different morphologies have solvothermally prepared with ethylenediamine (en) and glycol as solvents. Solvent-dependent experiments were carried out by adjusting the ratios of en/glycol to investigate the effects of the solvents on the product phase formation and morphology. It was found that the morphology of CdS nanocrystallite develops from a rough spherical nanoparticle to a rod-, twinrod-, and tetrapod-shaped nanoparticle by increasing the ratio of en/glycol, meanwhile the phase composition changes from coexistence of tetragonal zinc blende CdS and hexagonal wurtzite CdS to pure hexagonal wurtzite CdS. Based on the experimental results, a possible shape evolution mechanism of CdS nanocrystallites is simply discussed.

Abstract: The paper discusses the modulus of elasticity of plain concrete for a wide range of compressive strength. A large volume of selected experimental data has been collected from existing literature and then analyzed. Particular emphasis has been given to studying the effects of concrete compressive strength and the type of coarse aggregate on the modulus of elasticity of plain concrete. The adequacy and applicability of the existing models for predicting the modulus of elasticity of high-strength concrete has been critically examined, and a new empirical model is proposed to cover concrete strength up to 125 MPa. The new empirical model seems to perform much better when applied to the published experimental data on normal weight concrete over a wide strength range.