Tuning peculiar antimony micro- and nano-morphology via a novel electrodeposition approach

Antimony (Sb) microspheres composed of antimony nanoplates or nanoparticles were synthesized via a novel electrodeposition technique onto the top surface of porous anodic alumina membrane (AAM) after the growth of antimony nanowires. The two kinds of morphologies could be controlled by altering the experimental parameters, and the size of the nanoplates could also be tuned by adjusting the deposition potential. Besides, the micro- and nano-structure had relative narrow size distribution. Based on the experimental results, the possible growth mechanism was also proposed briefly. The method demonstrated here extends the application of AAM and can be used to synthesize other micro- and nano-structured materials.     

Influence of Stratification and Shoreline Erosion on Reservoir Sedimentation Patterns

Sedimentation in the main pool of a deep (maximum depth: 50?m), 227?km2 hydropower reservoir was modeled using a three-dimensional numerical model of hydrodynamics and sedimentation for different wind, inflow, and outflow conditions. Short-term velocity measurements made in the reservoir were used to validate some aspects of the hydrodynamic model. The effects of thermal stratification on sedimentation patterns were investigated, since the reservoir is periodically strongly stratified. Stratification alters velocity profiles and thus affects sedimentation in the reservoir. Sedimentation of reservoirs is often modeled considering only the deposition of sediments delivered by tributaries. However, the sediments eroding from the shorelines can contribute significantly to sedimentation if the shorelines of the reservoir erode at sufficiently high rates or if sediment delivery via tributary inflow is small. Thus, shoreline erosion rates for a reservoir were quantified based on measured fetch, parameterized beach profile shape, and measured wind vectors, and the eroded sediments treated as a source within the sedimentation modeling scheme. The methodology for the prediction of shoreline erosion was calibrated and validated using digital aerial photos of the reservoir taken in different years and indicated approximately 1?m/year of shoreline retreat for several locations. This study revealed likely zones of sediment deposition in a thermally stratified reservoir and presented a methodology for integration of shoreline erosion into sedimentation studies that can be used in any reservoir.     

Interface growth morphologies in pulsed laser deposited, room temperature grown multilayer hard coatings

The mechanical behaviour - hardness, elasticity, and adhesion - of multilayer coatings is strongly influenced by the type of the formed interfaces between the different layers. In industrially applied tribological coatings the interface region is predominantly not a perfect sudden change of the chemical composition of the adjacent crystal planes, but a transition zone of a thickness, which is strongly dependent on the energetic conditions during deposition. Multilayer coatings grown by high-energetic deposition techniques always struggle with high atomic mixing of both adjacent coating materials due to high energetic ion implantation.One of these high-energetic deposition techniques is the Pulsed Laser Deposition (PLD), characterized by pulsed and within one pulse alternating high- and low-energetic particle fractions, hitting successively the substrate surface. Such deposition conditions were shown to be highly advantageous for low temperature deposition by the densification of the growth structures due to activated diffusion and re-sputtering, but increases the difficulty in depositing multilayer structures.The current paper addresses these specific growth conditions based on Ti/TiN and Cr/CrN multilayer coatings. High resolution transmission electron microscopy results show that the atomic mixing at the interface is not highly critical for the deposition of multilayer coatings and that extremely dense growth structures are forming even in the interface regions.     

Influence of processing variables on the structure and properties of ZnO films

Zinc oxide films of high optical quality have been deposited onto both silica and silicon substrates using reactive sputtering, pulsed laser deposition, and an aqueous solution based technique. Films have been characterized with respect to crystalline phase and phase stability, surface morphology, and optical response by means of X-ray diffraction, Raman spectroscopy, atomic force microscopy, optical transmission and ellipsometry measurements. All films studied were of the wurtzite phase, fine-grained, and exhibited varying degrees of c-axis orientation with respect to the substrate normal depending upon deposition conditions. Films showed some degree of residual tensile stress which was inferred from the E₂ Raman line shift relative to the single-crystal frequency. The wurtzite phase was found to be stable to temperatures near 800 °C, but at higher temperatures, reaction with silica led to evolution of Zn₂SiO₄ at the interface. Variations in Raman line intensities upon post-deposition annealing have been correlated with oxidation of excess zinc in the lattice.     

吐哈油田生产井蜡沉积物系统分析及蜡沉积机理探讨

用溶剂萃取分离，气相色谱，红外光谱、核磁共振等方法分析研究了吐哈油田特别是鄯善油田生产井的蜡沉积物，吐哈原油中的蜡按烷烃碳数分布有Ｃ１３－Ｃ３５和Ｃ３０－Ｃ６５两个峰区，其中第二峰区的高碳石蜡含量超过蜡总含量的５０％，蜡熔点很高，为８４－１００℃，基本上是不带支链的纯粹正构烷烃，极易从原油中析出。对蜡沉积作了初步探讨和推论。     

Thermophoretic deposition of small particles in a direct numerical simulation of turbulent channel flow

This paper presents results for the deposition rate of small particles on the walls of a turbulent channel flow. The results were obtained by direct numerical simulation of a horizontal turbulent channel flow. A temperature profile typical of ceramic oxide aerosol reactors was imposed across the channel. Thermophoresis played an important role in the deposition of particles for the range of conditions that were studied. An interaction between turbophoresis and thermophoresis was found to play an important role in the deposition process.     

中国含油气盆地的演化

本文从中国各个地质时期的地壳运动和沉积古地理出发，综合分析了晚古生代以来中国陆相含油气盆地的演化特点，提出了二叠纪湖盆发育于新疆北部，晚三叠纪湖盆主要发育于陕甘宁地区，侏罗纪时期中国西部大面积沉降，发育众多的大型湖盆，水域面积大，西部湖盆较东部发育。早白垩纪晚期以后，中国西部上升而东部开始沉降，早白垩纪晚期发育了松辽湖盆，早第三纪发育了渤海湾、苏北、江汉和海上大陆架诸多湖盆。以上这些大型古湖盆都是油气生成的有利场所。     

Rotatable magnetron sputtering of aluminium in continuous and high power pulse modes using different strength magnetic arrays

This paper reports preliminary results of industrial size (152 mm target O.D.) rotatable magnetron sputtering of Al target in direct current (DC) and High Power Impulse Magnetron Sputtering (HIPIMS) modes using two standard commercially available magnetic arrays: standard strength array (as used for DC and AC processing) and a lower strength ‘RF’ array [i.e. as used for radio frequency (RF) magnetron sputtering]. A comparison of processes resulted in by combining the different magnetic arrays and power modes is made in terms of magnetic field distribution on the cathode surface, magnetron characteristics, process characteristics and deposition rates.Optical emission spectroscopy (OES) revealed enhanced sputtered Al flux ionisation in the HIPIMS discharge monitored 64 mm away from the target surface when using the ‘RF’ array. Importantly, the results of this work (at the processing conditions investigated) demonstrate that at the same average power the deposition rate of Al using HIPIMS in conjunction with the ‘RF’ array is substantially the same as that obtained for the ‘standard’ strength balanced array and DC power. This indicates that the magnetic field design of the ‘RF’ magnetic array affects favourably the sputtered flux transport perpendicular to the target surface by altering mass transport direction and minimising effects that reduce deposition rate (e.g. ion return effect). Arc rate is also reduced significantly (approximately ten times) if the low strength ‘RF’ array is used.     

Synthesis and characterization of novel Ag-polypyrrole@poly(styrene-co-methacrylic acid) nanocomposite particles

Novel raspberry-like Ag-polypyrrole/poly(styrene-co-methacrylic acid) (Ag-PPy/P(St-co-MAA)) colloidal nanocomposite particles were prepared by aqueous oxidative polymerization of pyrrole using AgNO₃ as the oxidant. The polymerization was carried out in the pre-synthesized polymer-emulsion of P(St-co-MAA) with emulsifier-free P(St-co-MAA) latex particles serving as both the templates and the stabilizers. Without any extra surfactants or polymer stabilizers, the polymerization proceeded steadily with the in-situ produced Ag-PPy nanocomposites depositing on the surface of the template particles. The obtained product is typical of raspberry-like morphology, whose nanostructures and compositions were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and electron dispersive X-ray spectrometer (EDS), respectively. The results confirmed that the surface of the P(St-co-MAA) latex was coated by Ag-PPy nanocomposite particles with a size range from 2 nm to 50 nm. Most of Ag nanoparticles are encapsulated by the PPy sheath or dispersed in the PPy layer.     

Field emission properties of electrodeposited cobalt nanowire arrays grown in anodic aluminum oxide

The excellent vertically aligned cobalt nanowire arrays were electrodeposited into anodic aluminum oxide (AAO) templates. Each nanowire has the same length with 20 μm and the diameter with 60 nm. The field emission characteristics of the nanowires were firstly studied based on current-voltage measurements and the Fowler-Nordheim equation. The electron field emission measurements on the samples showed a turn-on field (1 mA/cm²) of 1.66 V/μm, a field enhancement factor of β = 3054 and a current density of 600 mA/cm² at a relatively low voltage of 4.3 V/μm. The nanowire arrays could be an ideal alternative to carbon nanotubes and ZnO nanowires for the fabrication of flat panel displays.