An outward coating method has been successfully employed to prepare CuO/MnO2 nanorod array films based on the impregnation of Cu­(OH)2 nanorod array films with manganese nitrate aqueous solution and heat post-treatment. The as-prepared CuO/MnO2 nanorod array films as heterogeneous catalysts successfully address such issues as easy agglomeration, difficult separation, and possible secondary pollution related to powder catalysts. Furthermore, they exhibit catalytic oxidation activity for the degradation of acid fuchsin (AF) dye in aqueous solution superior to that of bare CuO nanorod array films in the presence of H2O2, because of the synergistic effects of both CuO and MnO2. The effects of the initial concentration of aqueous AF solution and H2O2 dosage on the catalytic oxidation performance were evaluated, indicating that the degradation ratio of AF can reach up to 94.05%. Life-cycle performance and scaleup of the catalytic oxidative degradation process demonstrate the durability and potential engineering application of CuO/MnO2 nanorod array films in dye wastewater treatment.

Well-aligned ZnSe nanotube arrays with diameters of 300−400 nm and wall thicknesses of 60−70 nm have been controllably prepared based on a replacement/etching method, with ZnO nanorod arrays on zinc substrate as sacrificial templates. An obvious difference of the solubility product (K sp ) between the ZnSe wall and ZnO core materials is crucial for the direct replacement of one type of anions by the other. Ammonia as the chemical etching agent is also important for dissolving ZnO nanorod core. The photocatalytic activities of the as-prepared ZnSe nanotube arrays have been studied for the degradation of methyl orange aqueous solution and compared with those of ZnO nanorod arrays and the intermediates including ZnO/ZnSe core/sheath nanorod arrays and partially dissolved ZnO core/ZnSe sheath nanorod arrays, respectively. The results indicate that ZnSe nanotube arrays exhibit superior photocatalytic performance to the other three nanostructured arrays, which can be mainly attributed to their full hollow interior nanotubes providing more accessibility to the dye molecules and more reactive adsorption/ desorption sites for photocatalytic reactions. Furthermore, the ZnSe nanotube arrays have successfully overcome the shortcomings related to photocatalyst recovery and stability, which the powder-form photocatalysts usually face. ZnSe nanotube arrays as photocatalysts are expected to be promising in sewage water treatment.

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Using 3D finite element method (FEM) modelling, the present work investigates the coupling effect between two finite superconductors through a resistive matrix. This effect, related to the finite length of the conductors, is typically three-dimensional and cannot be analysed by the widely utilized 2D models. Superconductors are modelled with the nonlinear power-law E = E c (J /J c ) n , which has been implemented in the FEM software. The main focus is to demonstrate the feasibility of such calculations and to establish the correlation between the coupling effect and the aspect ratio of the conductor cross-section, in order to extend the existing theory, which is only precise for superconductors of infinite slabs, fully penetrated by the magnetic field. The effect of other parameters such as the conductor length and the gap between the superconducting filaments is also considered. The latter is a parameter which does not feature in the approximate theories.

Suzuki (2004) [7] classified thin weakly distance-regular digraphs and proposed the project to classify weakly distance-regular digraphs of valency 3. The case of girth 2 was classified by the third author (2004) [9] under the assumption of the commutativity. In this paper, we continue this project and classify these digraphs with girth more than 2 and two types of arcs.

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