Evaluation of the biodegradation product layer on Mg-1Zn alloy during dynamical strain

Magnesium (Mg) alloys are attractive biodegradable implant materials. The degradation products on Mg alloys play a critical role in the stability of the interface between implant and surrounding tissue. In the present study, the effects of dynamic deformation on the interface layer of biomedical Mg-1Zn alloy were investigated using the constant extension rate tensile tests (CERT) coupled with electrochemical impedance spectroscopy (EIS). The deformation of the Mg-1Zn alloy had an adverse influence on the impedance of the surface degradation layer formed in simulated body fluid that only containing inorganic compounds. However, the surface degradation layer with improved corrosion resistance was obtained for the strained samples tested in protein-containing simulated body fluid. The spontaneous or enhanced adsorption of protein into the degradation product led to a flexible and stable hybrid anti-corrosive layer. A relationship between the dynamic deformation of Mg alloy and the impendence of the degradation layer was established, which demonstrates the necessity for in situ characterisation of the evolution of the surface layer under dynamic condition

Dispersion characteristics of nanometer-scaled silicon rib waveguides

We investigate the dispersion properties of nanometer-scaled silicon waveguides with channel and rib cross section around the optical fiber communication wavelength and systematically study their relationship with the key structural parameters of the waveguide. The simulation results show that the introduction of an extra degree of freedom in the rib depth enables the rib waveguide more flexible in engineering the group velocity dispersion (GVD) compared with the channel waveguide. Besides, we get the structural parameters of the waveguides that can realize zero-GVD at 1550 nm