Dehydration of tetrafluoropropanol (TFP) by pervaporation via novel PBI/BTDA-TDI/MDI co-polyimide (P84) dual-layer hollow fiber membranes

A novel PBI/P84 co-polyimide dual-layer hollow fiber membrane has been specifically fabricated through the dry-jet wet phase inversion process, for the first time, for the dehydration pervaporation of tetrafluoropropanol (TFP). Polybenzimidazole (PBI) was chosen as the outer selective layer because of its superior hydrophilic nature and excellent solvent-resistance together with robust thermal stability, while P84 co-polyimide was employed as the inner supporting layer because of its good solvent-resistance and thermal stability. The PBI/P84 membrane exhibits superior water selectivity and relatively high permeation flux. At 60 °C, the PBI/P84 dual-layer hollow fiber membrane shows a permeation flux of 332 g/(m² h) and a separation factor of 1990 for a feed solution containing of 85 wt% TFP. The preferential water sorption and the significant diffusivity difference between TFP and water are the main causes of high separation factor. However, an increase in feed temperature will greatly increase the permeation flux but seriously decrease the water selectivity. The activation energy data verify that water can preferentially permeate the PBI membrane due to the strong water affinity of PBI and a much smaller molecular size of water.     

全要素生产率和产业结构对能源利用影响的实证分析

本文利用能源消耗模型进行实证分析,结果表明决定能源利用效率的关键因素和长期因素是全要素生产率,全要素生产率的不断提高导致了我国经济快速发展而单位GDP能源消耗不断降低的特殊现象.产业结构对能源消耗有显著的短期影响,当第一产业比例下降或第二产业比例上升时,能源消耗增加。市场化程度、对外开放程度对能源消耗的作用体现在全要素生产率中.2000年后能源消耗重新抬头并不否定全要素生产率的作用,而是缺乏节能意识的负面影响抵消并逆转了全要素生产率的正面作用.     

Colour Adaptation in Three Fringe Photoelasticity

Three fringe photoelasticity (TFP) can give the total fringe order from a single colour isochromatic fringe field by suitably comparing the colour with a calibration specimen. The fringe order evaluation can be erroneous when the materials for the calibration specimen and the application specimen are different. This is because of the colour variation between the two materials. This is conventionally handled by preparing individual calibration tables for each application. A new methodology to tune the calibration table obtained for a single material to accommodate the tint variation in TFP is proposed for the use of different specimen materials. Discontinuities in fringe order variation are smoothed using the refined TFP (RTFP) procedure. The elegance of the new methodology for solving a multi-material system is bought out by solving the problem of a bi-material Brazilian disc. The results obtained are compared with the phase shifting technique.     

全要素生产率对中国经济增长方式的实证研究

运用计量经济学中的状态空间模型,对改革开放以来中国全要素生产率增长的变动情况进行研究,并且比较分析了资本、劳动的要素投入和全要素生产率对经济增长的贡献.此外,还分别对东、中、西部各地区的全要素生产率的增长变化进行了分阶段比较研究.作者发现,资本投入的增长仍然是推动中国经济增长的主要动力;劳动投入的增长对经济增长的贡献较为稳定,但水平相对较低;全要素生产率的增长对经济增长的贡献随时间变化明显;各地区全要素生产率的增长在不同阶段有着截然不同的表现.     

Biological activity studies on organotin(IV) complexes and parent compounds

This review summarized the literature and own data on the parent organotin(IV) compounds and complexes formed with biologically active ligands.     

高新技术产业技术创新的全要素生产率及其分解

使用DEA-Malmquist方法与Bootstrap方法相结合,对2000-2010年间我国省际高新技术产业技术创新的全要素生产率变动进行了测算,并给出了效率估计值的显著性水平,保证了研究结论的准确性和稳健性.研究结果显示,2000-2010年间我国高新技术产业技术创新的全要素生产率处于不断波动中,技术创新效率的改进并不理想;从三大区域和各省市的情况来看,高新技术产业技术创新的TFP变动方向存在显著差异.     

中国钢铁业上市公司并购中盈余管理研究—基于效率视角

本文通过改进度量盈余管理程度的Yoon-miller模型,测算2003-2009年中国钢铁业上市公司并购前后的可操纵性利润和全要素生产率,并对并购中盈余管理与效率的内在关系进行分析。结果表明:并购后一年全要素生产率有效的钢铁上市公司在并购当年存在向上的盈余管理,并购后一年及并购当年全要素生产率均有效的钢铁上市公司,在并购后一年容易进行较大幅度的向下盈余管理行为。     

浙江省全要素生产率的估算和分解——基于非参数Malmquist生产率指数法研究

运用非参数Malmquist生产率指数方法,对浙江省11个地区的全要素生产率进行了估算和分解.估算结果表明：“八五计划”和“九五计划”期间,所有地区的TFP增长迅速,而“十五规划”期间,大部分地区的TFP则下降显著;进一步分解发现各地区的技术效率是收敛的,对TFP的影响较小,而技术变动与TFP波动趋势相同,对TFP变动起决定作用.     

Trifluoperazine effects on anionic and zwitterionic micelles: a study by small angle X-ray scattering

In this work small angle X-ray scattering (SAXS) studies on the interaction of the phenothiazine trifluoperazine (TFP, 2-10 mM), a cationic drug, with micelles of the zwitterionic surfactant 3-(N-hexadecyl-N,N-dimethylammonium) propane sulfonate (HPS, 30 mM) and the anionic surfactant sodium dodecyl sulfate (SDS, 40 mM) at pH 4.0, 7.0, and 9.0 are reported. The data were analyzed through the modeling of the micellar form factor and interference function, as well as by means of the distance distribution function p(r). For anionic micelles (SDS), the results evidence a micellar shape transformation from prolate ellipsoid to cylinder accompanied by micellar growth and surface charge screening as the molar ratio TFP:SDS increases in the complex for all values of pH. Small ellipsoids with axial ratio nu=1.5+/-0.1 (long dimension of 60 A) grow and reassemble into cylinder-like aggregates upon 5 mM drug incorporation (1 TFP:8 SDS monomers) with a decrease of the micelle surface charge. At 10 mM TFP:40 mM SDS cylindrical micelles are totally screened with an axial ratio nu approximately 4 (long dimension approximately 140 A at pH 7.0 and 9.0). However, at pH 4.0, where the drug is partially diprotonated, 10 mM TFP incorporation gives rise to a huge increase in micellar size, resulting in micelles at least 400 A long, without altering the intramicellar core. For zwitterionic micelles (HPS), the results have shown that the aggregates also resemble small prolate ellipsoids with averaged axial ratio approximately nu=1.6+/-0.1. Under TFP addition, both the paraffinic radius and the micellar size show a slight decrease, giving evidence that the micellar hydrophobic core may be affected by phenothiazine incorporation rather than that observed for the SDS/TFP comicelle. Therefore, our results demonstrate that the axial ratio and shape evolution of the surfactant:TFP complex are both dependent on surfactant surface-charge and drug:surfactant molar ratio. The results are compared with those recently obtained for another phenothiazine drug, chlorpromazine (CPZ), in SDS and HPS micelles (Caetano, Gelamo, Tabak, and Itri, J. Colloid Interface Science 248 (2002) 149).