The mechanism concerning mesopore formation remains unclear to date. In this letter, linear nuclei were pre-structured on purpose; anodizing with aqueous HF electrolyte, one-dimensional (1D) arrays of mesopores with depths up to 40 μm and diameters down to 20 nm (aspect ratios up to 1300) were fabricated in the dark. Significantly higher pore densities and markedly weaker branches occurred in comparison to randomly formed mesopores. Pore densities could increase with decreased current densities. Breakdown effects combined with current-burst-model were employed to interpret the underlying mechanism in detail; SCR (space charge region) effects were excluded as additional stabilizer of the 1D mesopore arrays. 相似文献
Cyclic voltammograms in dimethylsulphoxide (DMSO) are presented and discussed for para- and meta-nitro-substituted N(thiobenzoyl)piperidines (1a, 2a) and morpholines (lb,2b) as well as for the corresponding N(thiocinnamoyl) derivatives (3b, 4a, b). In the first cycle, two main reduction waves (A, B) were found for compounds 1a, b, 3b, 4a, b, and only one (A) for 2a, b. In the second cycle, a new wave (D) appears at a potential less negative than A, indicating the formation of a new redox system.The electrochemial data were interpreted in terms of the following EECE mechanism; The species P− obtained during the reduction of 3b was unambiguously identified by means of ESR spectroscopy as the anion radical of p-nitrobenzaldehyde. For 1a, b it was assumed on similar grounds that P− is the p-nitrobenzoate anion radical.The formation of these species is accounted for by the chemical reaction of the dianion with the residual water present in the solvent. 相似文献
Hollow fiber microfiltration (MF) and ultrafiltration (UF) membrane processes have been extensively used in water purification and biotechnology. However, complicated filtration hydrodynamics wield a negative influence on fouling mitigation and stability of hollow fiber MF/UF membrane processes. Thus, establishing a mathematical model to understand the membrane processes is essential to guide the optimization of module configurations and to alleviate membrane fouling. Here, we present a comprehensive overview of the hollow fiber MF/UF membrane filtration models developed from different theories. The existing models primarily focus on membrane fouling but rarely on the interactions between the membrane fouling and local filtration hydrodynamics. Therefore, more simplified conceptual models and integrated reduced models need to be built to represent the real filtration behaviors of hollow fiber membranes. Future analyses considering practical requirements including complicated local hydrodynamics and nonuniform membrane properties are suggested to meet the accurate prediction of membrane filtration performance in practical application. This review will inspire the development of high-efficiency hollow fiber membrane modules. 相似文献
InGaN-based light-emitting diodes with p-GaN and p-AlGaN hole injection layers are numerically studied using the APSYS simulation software.The simulation results indicate that light-emitting diodes with p-AlGaN hole injection layers show superior optical and electrical performance,such as an increase in light output power,a reduction in current leakage and alleviation of efficiency droop.These improvements can be attributed to the p-AlGaN serving as hole injection layers,which can alleviate the band bending induced by the polarization field,thereby improving both the hole injection efficiency and the electron blocking efficiency. 相似文献