荷负电手性壳聚糖纳复合滤膜的制备与性能研究

以聚砜超滤膜作为基膜,以壳聚糖和壳聚糖衍生物的混合物为功能层制备纳滤膜。P2-5复合纳滤（NF）膜对Na2SO4的截留率为93%,相应的通量501.3 L/（m2·h）。电荷效应对NaCl几乎没有影响,而对Na2SO4影响显著。该膜为典型的荷负电膜,适合分离高价阴离子。     

TS-271清洗剂在清洗预膜案例中的应用

石家庄某公司循环冷却水系统停车检修期间进行了系统清洗预膜维护,通过对现场垢样的分析,进行了筛选清洗剂的一系列评价实验,现场清洗预膜效果良好,保障了循环水系统的正常运行。     

Hydrogen Acceptor‐ and Base‐Free N‐Formylation of Nitriles and Amines using Methanol as C1 Source

An N‐formylation method using methanol as the C₁ source without a stoichiometric amount of activating reagent is described. Nitriles as well as amines can be directly used as substrates. The reaction is catalyzed by an N‐heterocyclic carbene coordinated ruthenium(II) dihydride complex, which mediates methanol dehydrogenation, nitrile reduction, and C N bond formation without any external base, hydrogen acceptor, or oxidant.

     

基于混沌粒子群优化算法的NOMA功率分配研究

非正交多址接入(NOMA)技术使多个用户共享一个时频资源块,显著地提高了频谱利用率,已成为5G多址技术的研究热点。针对NOMA系统能量效率最大化问题,对非正交多址接入技术中功率分配进行了研究,提出了基于混沌粒子群优化算法的NOMA功率分配方案。建立了能量效率最大化的NOMA优化模型,利用混沌粒子群优化算法对系统功率进行分配,使NOMA系统的能量效率得到优化。仿真结果表明,当发射功率为36 dBm时,系统能量效率最大,且与传统粒子群算法相比所需迭代次数更少,获得的能量效率更优。     

Fabrication of Titanium Bipolar Plates by Rubber Forming Process and Evaluation Characteristics of TiN coated Titanium Bipolar Plates

In this study, the rubber forming process is used to fabricate a micro‐channel titanium plate for a PEM fuel cell. The micro‐channel plate is fabricated using a 200 ton hydraulic press, and various parameters (punch speed, press pressure, rubber thickness, rubber hardness) are investigated in order to evaluate the formability. TiN films are deposited by reactive DC magnetron sputtering (DCMS) with an electromagnetic field system (EMFS). For the uncoated titanium and TiN‐coated titanium substrates, the hardness, surface roughness, and corrosion resistance are estimated by nano‐indentation and electrochemical methods, respectively. The improved corrosion resistance of the TiN films can be attributed to the densification of the film caused by enhancement of nitrification with increasing high reactive nitrogen radicals. The uncoated titanium and TiN‐coated titanium bipolar plates are combined with a unit cell for a performance test, and respective current densities of 0.396 and 0.888 A cm⁻² at 0.6 V are obtained.     

远红外聚丙烯熔喷超细纤维非织造布的研究

研制了一种含有纳米陶瓷粉的聚丙烯熔喷超细纤维非织造布,采用电子扫描显微镜分析了该熔喷非织造布的纤网形态结构,并对其透气性、透湿性以及远红外功能等进行了测试。结果表明:加入纳米陶瓷粉之后,熔喷非织造布纤网结构变得稀疏,其透气、透湿性能都有所提高;当纳米陶瓷粉含量为8%时,聚丙烯熔喷非织造布的远红外发射率达82%,是一种优良的保暖絮片。     

吸尘器滤芯用复合型针刺非织造布的研制与开发

针刺非织造过滤材料在很多领域已经得到应用,并且发展非常迅速。叙述吸尘器滤芯用复合型针刺非织造布的生产工艺,并将其成品与其他产品进行了比较,结果表明复合型针刺非织造布的各项性能都优于其他同类产品。     

Polymerization kinetics of polyurethane and vinyl ester resin interpenetrating polymer networks by using fourier transform infrared spectroscopy

Fourier transform infrared spectroscopy (FTIR) was applied to the study of polymerization kinetics of simultaneous interpenetrating polymer networks (SINs) composed of polyurethane (PU) and vinyl ester resin (VER), in which the pendent hydroxyl groups were capped with acetyl groups to minimize the possibility of chemical binding between the two networks. It was found that during the course of synthesis the two pairs of reactants interfere with each other in the SIN systems, giving rise to depressed reaction rates, although they follow different polymerization mechanisms. Increasing the reaction temperature could be more effective than increasing the free-radical initiator level with regard to the final conversions of both components. The reaction sequence could be varied through the amount of the step-growth polymerization catalyst and free-radical initiator as well as the reaction temperature adjustment. Using VER containing pendent hydroxyl groups could strongly affect the reaction kinetics of such SINs and lead to hybrid structures. The quick formation of one network would always depress the conversion of the other network in all SINs studied. © 1996 John Wiley & Sons, Inc.     

Modeling of semibatch direct esterification reactor for poly(ethylene terephthalate) synthesis

A comprehensive kinetic model for a semibatch direct esterification reactor has been developed. The solid-liquid equilibirium of terephthalic acid was considered in the modeling. Effects of the monomer feed ratio, reaction temperatures, and oligomer addition on the conversion, degree of polymerization, and the formation of diethylene glycol were studied. © 1996 John Wiley & Sons, Inc.     

Surface crystalline characteristics of polyurethane investigated by atomic force microscopy

A polyester—urethane was synthesized by the reaction of 2,4-toluylene diisocyanate (TDI) with poly(butylene glycol adipate) (PBGAD) using 1,4-butanediol (BDO) as a chain extender. Atomic force microscopy was employed to examine the surface morphologies of polyurethane (PU) films formed by heat treatment as well as at room temperature. At both conditions the surface of the PU film appeared as a spherulitic structure with a varied diameter and vertical height. Furthermore, the crystalline structure of heat-treated film was denser than that of the film formed at ambient. © 1996 John Wiley & Sons, Inc.