A study on the antibacterial activity of one-dimensional ZnO nanowire arrays: effects of the orientation and plane surface

In this study, ZnO nanowire arrays with different orientations were prepared. Confocal laser scanning microscopy (CLSM) and field- emission scanning electron microscope (FE- SEM) technique were employed for understanding the disparities in antibacterial activity between different orientations of ZnO nanoarrays. The effects of the different planes of ZnO nanowire were also discussed for the first time.

Competition of lamellar orientation in thin films of a symmetric poly(styrene)-b-poly(L-lactide)diblock copolymer in melt state

We have studied the lamellar orientation in thin films of a model diblock copolymer, symmetric poly(styrene)-b-poly(L-lactide) (PS-PLLA), in the melt state on supported silicon wafer surface. In this system, while the PLLA block prefers to wet the polymer/substrate interface, the polymer/air as well as polymer/polymer interface is neutral for both blocks due to the similar surface energies of PS and PLLA in melt state. Our results demonstrate that the interplay of the interfaces during phase separation results in a series of structures before approaching the equilibrium state. Lamellar orientation of thin films with different initial film thicknesses at different annealing stages has been investigated using atomic force microscopy (AFM), transmission electronic microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It is found that in the early stage (annealing time t < 10 min), the polymer/substrate interface dominates the structure evolution, leading to a parallel lamellar structure with holes or islands formed depending on the initial film thickness. Later on, the neutral air interface becomes important and leads to a transition of lamellar orientation from parallel to perpendicular. It is interesting to see that for films with thickness h > 2L, where L is the bulk lamellar period, the lamellar orientation transition can occur independently in different parallel lamellar domains due to the neutrality of polymer/polymer interface.

Orientation and electrocatalysis of riboflavin adsorbed on carbon substrate surfaces

Based on scanning tunnelling microscopy and electrochemical measurements, orientation and electrocatalytic function of riboflavin adsorbed on carbon substrates have been described for the first time. Scanning tunnelling micrographs show clearly that tip induction may result in an orientation change of the adsorbed riboflavin molecule on highly oriented pyrolytic graphite from the initially vertical orientation to the stable flat form. The adsorbed riboflavin as an effective mediator can accelerate the reduction of dioxygen which accepts two electrons from the reduced riboflavin to generate hydrogen peroxide. The rate constants of the electrocatalytic reaction in various pH solutions were determined using a rotating disc electrode modified with riboflavin. The pH effect and possible catalytic mechanism are discussed in detail.