给水管网的分形

从管网生长的物理机制角度入手,对管网生长的分形特性进行了探讨,介绍了管网生长的动力源、速度、自组织生长过程,分析了管网形态各异的原因及其自仿射性,阐述了分形理论用于管网优化的前景,以期促进分形理论在管网工程中的应用。     

A versatile chemical conversion synthesis of Cu2S nanotubes and the photovoltaic activities for dye-sensitized solar cell

A versatile, low-temperature, and low-cost chemical conversion synthesis has been developed to prepare copper sulfide (Cu₂S) nanotubes. The successful chemical conversion from ZnS nanotubes to Cu₂S ones profits by the large difference in solubility between ZnS and Cu₂S. The morphology, structure, and composition of the yielded products have been examined by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements. We have further successfully employed the obtained Cu₂S nanotubes as counter electrodes in dye-sensitized solar cells. The light-to-electricity conversion results show that the Cu₂S nanostructures exhibit high photovoltaic conversion efficiency due to the increased surface area and the good electrocatalytical activity of Cu₂S. The present chemical route provides a simple way to synthesize Cu₂S nanotubes with a high surface area for nanodevice applications.     

Clinsulf-DO硫回收工艺

通过某厂 18- 30工程 Clinsulf- DO装置的引进过程 ,介绍了 Clinsulf- DO硫回收工艺的原理和特点     

Controllable ZnO nanostructures evolution via synergistic pulsed laser ablation and hydrothermal methods

We report the morphology-controlled ZnO nanostructures (ZNSs) evolution synthesized via a novel and facile technique at different growth times, where the pulse laser ablation in liquid (PLAL) is creatively combined with hydrothermal (H) method (hereafter called PLAL-H technique). Four types of ZNSs with varying sizes and shapes such as tapers, multipods, flowers, and hollow flowers are produced on Si substrate via PLAL-H technique. Furthermore, multipod- and flower-like ZNSs are grown using direct hydrothermal method to compare them with the one obtained via synergistic effects of PLAL-H method. This catalyst-free fabrication method is not only cost-effective but greatly useful for the rapid production of different quality of ZNSs at low temperature. ZNSs synthesized under prolonged growth time (60 min) exhibited structural deformation. Growth technique and time dependent morphology, structure, composition, and optical properties of these as-grown ZNSs are characterized using FESEM, X-ray diffraction, FTIR, photoluminescence, and UV–vis measurements. Synthesized ZNSs revealed excellent crystallinity and growth process dependent variation in the physical and optical features. The ZNSs growth mechanism is understood. Excellent features of the results demonstrate that this synergized new growth technique may constitute a basis for modifying the morphology, sizes, and optical properties of ZNSs in a controllable manner useful for diverse applications.     

Initial Growth of Single-Crystalline Nanowires: From 3D Nucleation to 2D Growth

The initial growth stage of the single-crystalline Sb and Co nanowires with preferential orientation was studied, which were synthesized in porous anodic alumina membranes by the pulsed electrodeposition technique. It was revealed that the initial growth of the nanowires is a three-dimensional nucleation process, and then gradually transforms to two-dimensional growth via progressive nucleation mechanism, which resulting in a structure transition from polycrystalline to single crystalline. The competition among the nuclei inside the nanoscaled-confined channel and the growth kinetics is responsible for the structure transition of the initial grown nanowires.     

Study of homogeneous chemical reactions at spherical electrodes and microelectrodes in Additive Differential Pulse Voltammetry

This is a theoretical work for the characterization of homogeneous chemical reactions coupled to a reversible electrode process and analyzed by Additive Differential Pulse Voltammetry at spherical electrodes or microelectrodes. Explicit analytical expressions are presented for the CE and EC mechanisms valid for spherical electrodes of any radius and fast chemical reactions. These enable us to easily and rapidly analyze the response of these mechanisms even under very strong kinetic conditions.The ADPV technique proves to be very useful in the identification of the reaction mechanism and the characterization of the coupled chemical reaction by means of the values of the peak currents and potentials and the crossing potential, which can be measured with good accuracy from several ADPV experiments with different pulse heights. Simple criteria are given for discrimination between different situations where the electrode process is coupled to a homogeneous chemical reaction and, what is more difficult, to distinguish between an EC mechanism and an irreversible charge transfer process. Moreover, direct procedures for quantitative determination of kinetic and thermodynamic information are established.     

Measurements of the isochoric heatc v at the critical point of SF6 under microgravity: Results of the German Spacelab Mission D2

During the Second German Spacelab Mission D2 (April 26 to May 6, 1993) the isochoric specific heatc _v of SF₆ was measured along the critical isochore under microgravity conditions with a newly developed scanning radiation calorimeter. This calorimeter provided the possibility to perform comparable heating and cooling runs with variable ramp rates since the spherical sample cell was heated and cooled only by radiation. During the experimental time of 220 h, 11 heating and cooling runs with different ramp rates were performed in a temperature range ofT–T _c=±6 K. ApproachingT _c by cooling from the homogeneous one-phase region avoided significant temperature and density gradients in the fluid, which would have distorted the integral measurement ofc _v. The inhomogenities introduced by a finite ramp rate were greatly reduced by the fast dynamic temperature propagation (critical speeding up). Thec _v data achieved with slow cooling runs are in remarkably good agreement with the theoretical prediction more than one order of magnitude closer to the critical point than anyc _v measurements done so far. The preliminary value for the critical exponent is 0.107±0.02, and for the amplitude ratio we obtainedA ^–/A ⁺=1.94±0.07. In contrast to the cooling runs, the heating runs showed a strong hysteresis ofc _v. A comparison to 1g measurements is provided.Invited paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, USA.     

砂磨机微粉碎理论及技术参数的研究

介绍了砂磨机的粉碎机理和衡量指标,给出了砂磨机有关性能参数的设计公式和数据,提出了砂磨机今后的发展方向