Trioctylphosphine as Both Solvent and Stabilizer to Synthesize CdS Nanorods

High quality CdS nanorods are synthesized reproducibly with cadmium acetate and sulfur as precursors in trioctylphosphine solution. The morphology, crystalline form and phase composition of CdS nanorods are characterized by transmission electron microscopy (TEM), high-resolution TEM and X-ray diffraction (XRD). CdS nanorods obtained are uniform with an aspect ratio of about 5:1 and in a wurtzite structure. The influence of reaction conditions on the growth of CdS nanorods demonstrates that low precursor concentration and high reaction temperature (260 °C) are favorable for the formation of uniform CdS nanorods with 85.3% of product yield.     

Enhanced oxygen permeation through perovskite hollow fibre membranes by methane activation

Hollow fibre membranes of mixed conducting perovskite La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF) were prepared via the combined phase inversion and sintering technique. The fibres were tested for air separation with a home-made reactor under the oxygen partial pressure gradient generated by the air/He streams. Some fibres were in situ activated by introducing methane in the He sweeping gas at high temperatures. The activated membranes with new morphology were created by transforming the inner densified surface layer to a porous structure. Compared to the original membranes, the activated gave appreciable higher oxygen fluxes. At 800 °C, the oxygen fluxes were increased by a factor of 10 after activation was carried out at 1000 °C for 1 h.     

Controlling degradation and physical properties of chemical sand fixing agent‐poly(aspartic acid) by crosslinking density and composites

Poly(aspartic acid) (PASP) hydrogel crosslinked with 1,6‐ hexamethylene diamine was applied as sand fixing agent. The effect of crosslinking density of sand fixing agent on sand fixing property was studied. The relations between the degradation time and crosslinking density, sand fixing property, molecular weight, and mass loss were measured. It was found that the sand fixing property relied on the PASP crosslinking density and degradation time. The crust attained the maximal mechanical strength when the PASP crosslinking agent concentration was 0.0325 mol/L and the PASP hydrogel mass loss was 97.9% after 18 days. The composites added into PASP could increase mechanical property and prolong the degradation time when compared with the control. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of biodegradable amphiphilic thermo‐responsive multiblock polycarbonate and its self‐aggregation behavior in aqueous solution

Amphiphilic thermo‐responsive multiblock polycarbonates consisting of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) were facilely synthesized using triphosgene as coupling agent. The structures and molecular characteristics of the polycarbonates were confirmed by ¹H‐NMR, FT‐IR and Gel permeation chromatography (GPC). The crystallization behavior and thermal properties of the polycarbonates were studied using X‐ray diffraction (XRD), Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Surface tension measurements confirmed that the critical micelles concentration of polymeric micelles were concentration ranges, which varied from about 2–70 mg/L to 5–40 mg/L with increasing PEO/PPO composition ratio from 0.8 to 1. Dynamic light scattering (DLS) experiments showed bimodal size distributions, the aggregates size increased with increasing the concentration of the polycarbonates aqueous solutions. The size of the aggregates acquired from TEM was smaller than that from DLS owing to the fact that TEM gave size of the aggregates in dry state rather than the hydrodynamic diameter. The degradation process revealed that the degradation rate of the aggregates could be accelerated with an increase in temperature. Moreover, the more the polycarbonate was hydrophilic, the faster was its degradation. Rheological measurements suggested that these multiblock polycarbonates were thermo‐responsive and by regulating the PEO/PPO composition ratio they could form a gel at 37°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Development of a new high‐efficiency simple structure cyclone

A novel uniflow cyclone design was evaluated using three prototype cyclones. For the first two, the efficiency and Euler number were determined using airborne solid particles with a number mean diameter of 12.5 µm. Then a larger scale prototype based on the optimized geometry was compared with an existing conventional high efficiency cyclone and a vane‐induced uniflow cyclone, using mineral oil droplets with a number mean diameter of 8.9 µm. Both sets of experiments showed that the newly designed cyclone had a higher efficiency at a higher pressure requirement, in addition to the feature of a small footprint.     

Integration of ink jet and transfer printing for device fabrication using nanostructured materials

Low viscosity, dilute inks of carbonaceous materials that tend to run, spread, and dry unevenly pose a major challenge towards ink jet printing approaches. A porous, planar stamp based methodology outlined here combines the advantages of ink jet and transfer printing while enabling printing of dilute inks comprising nanowires, nanotubes, nanoparticles, and biological molecules. Integration of ink jet and transfer printing is reported with agarose gel planar stamp, for carbon nanotube inks, enabling the formation of gate modulated channels between source and drain electrodes without necessitating any lithography steps.     

一类复杂组合结构有限元网格的自动剖分方法及其在工程中的应用

有限元网格的自动剖分法很多，但他们都是局限于某些单一的简单结构[1]，或者是针对某些特殊类型的单元而言[2]，本文提出一种象水轮发电机转子支架，水轮机顶盖等具有旋转对称性的复杂组合结构的有限元网格的自动剖分方法和网格的一种优化方法，最后还给出几个在工程实际结构分析中的应用实例。     

课程设计嵌合生产实习的PBL教学模式探讨

文章阐述了课程设计与生产实习嵌合的PBL教学方法的尝试,探讨了以学生为主体的主动学习型的教学模式,以促进学生从实践环节中有效获取应用性知识的能力。     

不锈钢内衬纤维复合材料球形高压容器研制

采用高强芳纶Ⅱ和凯芙拉-49纤维及不锈钢内衬,研制出小型球形环氧树脂基纤维复合材料压力容器。主要介绍了容器的结构材料、设计、试验方法。通过容器的密封性检验及贮存前后的液压爆破试验,结果表明,容器的设计是成功的,满足了设计使用要求。与同类钢制压力容器相比,在内径、外径、工作压力、安全系数相同情况下,该复合材料容器质量可减轻60%以上,漏率小于1×10-8Pa.m3/s,且贮存3年后爆破压力不会下降并略有提高。     

Characterization of synthetic and activated sludge and conditioning with cationic polyelectrolytes

This study investigates the effect of cationic polyelectrolytes on the final properties of synthetic and activated sludge. Synthetic sludge was prepared according to established procedures. Activated sludge was produced in a labscale, continuous-flow reactor which was fed with live activated sludge from a waste-water treatment plant. Capillary suction time (CST) was used to evaluate the sludge dewatering behaviour. The results from experiments indicated that the cationic polyelectrolytes had a critical effect on sludge dewatering, and made an improvement in the final properties of sludge. The two types of sludge have very similar dewatering characteristics after cationic polymer conditioning. The development of synthetic sludge is suggested also to be a possible surrogate for studying the final properties of activated sludge.