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.     

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.     

Removal of Remazol Brilliant Blue R dye from aqueous solutions by adsorption onto immobilized Scenedesmus quadricauda: Equilibrium and kinetic modeling studies

The green algae Scenedesmus quadricauda was immobilized in alginate gel beads. The immobilized active (IASq) and heat inactivated S.quadricauda (IHISq) were used for the removal of Remazol Brilliant Blue R (CI 61200, Reactive Blue 19, RBBR) from aqueous solutions in the concentration range 25-200 mg L^− 1. At 150 mg L^− 1 initial dye concentration the IASq and IHISq exhibited the highest dye uptake capacity at 30 °C, at the initial pH value of 2.0. At the same initial dye concentration in the batch system the adsorption capacity was determined for IASq as 44.2; 44.9 and 45.7 mg g^− 1 in 30, 60 and 300 min, respectively. After 300 min the adsorption capacity hardly changed during the adsorption time. The IHISq of adsorption capacity was observed as 47.6; 47.8 and 48.3 mg g^− 1 in 30, 60 and 300 min, respectively. After 300 min the adsorption capacity was not changed for 24 h. The Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Flory-Huggins isotherm models were used to fit the equilibrium biosorption data. The Langmuir, Freundlich and Dubinin-Radushkevich equations have better coefficients than Temkin and Flory-Huggins equation describing the RBBR dye adsorption onto IASq and IHISq. The monomolecular biosorption capacity of the biomass was found to be 68 and 95.2 mg g^− 1 for IASq and IHISq, respectively. From the Dubinin-Radushkevich model, the mean free energy was calculated as 6.42-7.15 kJ mol^− 1 for IASq and IHISq, indicating that the biosorption of dye was taken place in physical adsorption reactions. The experimental data were also tested in terms of kinetic characteristics and it was determined that the biosorption process of dye was well explained with pseudo-second-order kinetics.     

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.     

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.     

碳纳米管在氟碳树脂中的分散及其对光学性能的影响

采用球磨分散工艺制备了碳纳米管乙酸丁酯分散液,研究了分散剂的用量及分散时间对碳纳米管分散效果的影响.向上述分散液巾加入氟碳树脂制备成涂料,用扫描电子显微镜观察了碳纳米管在氟碳树脂中的分散状态,考察了分散状态对涂层热性能及光学性能的影响.     

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。     

膦甲酸钠苦参联合治疗慢性重型乙肝临床研究

目的了解膦甲酸钠(可耐)、苦参联合应用在慢性重型乙型肝炎患者中的抗病毒治疗效果及是否提高生存率。方法对78例血清定量阳性的慢性重型乙型肝炎随机抽取分为常规综合治疗组38例,男37例,女21例,年龄(45.6±20.5)岁;膦甲酸钠苦参治疗组40例,男37例,女23例,年龄(51.4±20.7)岁,2组临床资料相仿,P>0.05,具有可比性在综合疗法的基础上。治疗组在常规综合治疗上予以膦甲酸钠、苦参抗病毒治疗。对照组为常规综合治疗。结果膦甲酸钠苦参治疗组HBV-DNA阴转率25%,HBeAg阴转率为45%,临床有效率为72.5%;对照组HBV-DNA阴转率为7.89%;HBeAg阴转率为21.10%,临床有效率为42.10%。结论在综合疗法的基础上,应用膦甲酸钠加苦参治疗慢性重型乙型肝炎,安全有效,无明显不良反应,提高患者的生存率。