Advanced Materials Research Vol. 528

Abstract: Cu2S nanowire arrays with different morphologies were prepared by solid-gas reaction between Cu foil and mixture gas of H2S and O2. Their microstructures were observed with XRD, TEM, and the optical properties were measured by DRS, PL and Raman. The results showed that the nanowire were Cu2S single crystal with a thin layer CuxO (x=1, 2) over the surface. The optical properties of the Cu2S nanowire arrays are related to the diameter, length, and distribution density of nanowire arrays. The thinner is the nanowire’s diameter; the bigger is the absorption of the visible light, and the absorbance begun to descend within infrared band. The absorbance of nanowire arrays with bigger diameter to the infrared light was stronger than that with thinner diameter. The photoluminescence spectrum (PL) indicated that band gaps of Cu2S nanowire arrays also changed simultaneously with the nanowire arrays’ structure parameters. The research demonstrated the Cu2S nanowire arrays’ potential applications in the photovoltaic cell and solar-heat harvesting area.

Abstract: The objective is to study the stability of Nifeviroc-loaded microemulsions (Nifeviroc-MEs). The dilution stability of Nifeviroc-MEs with different loading capacity ( 0.1%, 0.2%, 0.3%) was tested by change of mean size, pH and appearance. The centrifugal stability was evaluated by comparing the mean size of Nifeviroc-MEs and dilutions before and after high-speed centrifugation for 30, 60, 120 min at 10000 rpm. The storage stability was evaluated by the change of appearance, the mean size, PDI and the retention rate of Nifeviroc in the ME. The pH, appearance, size analysis and retention rate results showed the Nifeviroc-MEs had good dilution, centrifugal stability and good storage stability without light.

Abstract: High-order surface effects can have a significant effect in the mechanical behavior of micro- and nano-sized materials and structures. In the literature the mathematical framework of surface/interface stresses are generally described by generalized Young-Laplace equations based on membrane theory. A refined model of surface stress, counting into surface stresses as well as surface moments, collectively referred to as high-order surface stress, was recently derived by the authors. This framework allows us to simulate the interface between two neighboring media which may have varying in-plane stress through the thickness of the thin membrane. To illustrate surface stress effects, we consider the critical force of axial buckling of nanowires by accounting various degrees of surface stresses. Using the refined Timoshenko beam theory, we incorporate the high-order surface effect in the simulation of axial buckling of nanowires. The results are compared with the solutions based on conventional surface stress model as well as existing experimental data. This study might be helpful to characterize the mechanical properties of nanowires in a wide range of applications.