A novel magnetic hierarchical nanocomposite based on ZnO nanowire/Fe3O4@SiO2 nanoparticle has been successfully synthesized by multistep chemical methods without calcinations. The magnetic cores of Fe3O4 act as the center for the growth of ZnO nanowires. As a result, the zinc oxide nanowires grown around Fe3O4 magnetic cores form a chestnut-like hybrid structure. The length of these ZnO nanowires was controlled by growth time. When used in the photodegradation of rhodamine B (RhB), these ZnO–Fe3O4@SiO2 nanocomposites show high photocatalytic activity. The large surface areas and the presence of nanowires, in which the electron transport rate is fasten to reduce the recombination of the photogenerated electrons and holes, are considered to make the major contribution to the enhanced photocatalysis. In addition, the as-obtained nanocomposites inherit the magnetic property from the Fe3O4 nanoparticles with the saturation magnetization (M s) about 3 emu/g. It has been demonstrated that this photocatalyst can be easily recycled by applying an external magnetic field and its high photocatalytic properties remain well after several recycles. This paper provides a convenient approach to synthesize recyclable magnetic photocatalysts.

The hydrothermal method is widely used to synthesize ZnO nanowires for electrical and optical devices. However, the rapid synthesis of long vertically aligned ZnO nanowire arrays on a transparent conductive oxide substrate is still a challenge and also time-consuming. In this paper, we report a controllable and rapid growth of long ZnO nanowire arrays by a microwave heating method with fresh precursor solution continuously injected into the reactor. This method can avoid the growth stoppage and keep the concentration of the reactants in dynamic equilibrium during the whole reaction. It is found that the length of the nanowires increases linearly with growth time, and the growth rate is as high as 58−78 nm/min, producing ZnO nanowires with a length over 10 μm after growing for 2−3 h. When these nanowire arrays were used as the photoanodes of dyesensitized solar cells (DSSC), the power conversion efficiency of these ZnO nanowire-based DSSCs increases with the length of the nanowires, which is mainly attributed to the enlarged internal surface area and therefore dye-loading amount enhancement in the longer ZnO nanowires. This controllable and rapid method is useful for synthesizing ZnO or other ultralong 1D nanostructure for nanodevices.

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Traffic movement conflict points at intersections are the points at which traffic movements intersect (including crossing, merging, and diverging). Numbers and distribution of different types of conflict points are used to evaluate intersection access management designs and safety performance. Traditionally, the determination of the numbers of conflict points for different traffic movements is based on manual methods, which causes the difficulty for computerized procedures to evaluate safety performance of different access management designs. Sometimes, a programmable calculation procedure may provide more effective solutions as compared with manual methods. This paper presents a programmable calculation procedure for the determination of the numbers of conflict points, which could be used as a basis for a computerized procedure. Concepts of virtual movement lanes and intersection quadrants are introduced to specify types of intersections, traffic lane configurations, and traffic movement regulations. Calculation models, based on such concepts, for traffic movement conflict points at signalized and unsignalized intersections can be obtained. In support of the procedure, case studies are presented in the paper. The procedure presented in the paper can be programmed into a computer program for the purpose of a computerized evaluation of intersection safety and design performance of different access management or control approaches.

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