Anionic triphenylamine‐ and fluorene‐based conjugated polyelectrolyte as a hole‐transporting material for polymer light‐emitting diodes

BACKGROUND: Hole‐transport layers (HTLs) play a crucial role in multilayer polymeric light‐emitting diodes (PLEDs) for the achievement of satisfactory device performance. During the fabrication of multilayer PLEDs via solution processing, the fabricated HTLs encounter the risk of erosion during the film‐forming process of subsequent emitting layers (EMLs). In contrast to the widely investigated crosslinkable HTLs, much less attention has been paid to the preparation of polar‐solvent‐soluble HTLs, which is a straightforward solution to overcome the interfacial mixing between HTLs and EMLs during solution processing. RESULTS: Alternating triphenylamine‐ and fluorene‐based anionic copolymer poly[9,9‐bis(4′‐sulfonatobutyl)fluorene‐alt‐N‐(p‐trifluoromethyl)phenyl‐4,4′‐diphenylamine]sodium salt (PFT‐CF3) was synthesized via a palladium‐catalyzed Suzuki coupling reaction. This polyelectrolyte is soluble only in polar solvents such as methanol, dimethylformamide and dimethylsulfoxide rather than in non‐polar solvents such as toluene, chloroform and xylene. The relatively high HOMO (?5.22 eV) and LUMO (?2.26 eV) levels of this polymer endow it simultaneously with good hole‐transporting and electron‐blocking capabilities. The performance of red‐, green‐ and blue‐emitting devices utilizing this polyelectrolyte as HTL was investigated. CONCLUSION: The anionic conjugated polyelectrolyte based on triphenylamine and fluorene, PFT‐CF₃, can serve as a promising hole‐transporting/electron‐blocking layer in multilayer PLEDs. Copyright © 2009 Society of Chemical Industry     

Comparing Approaches for Simulating the Reactive Transport of U(VI) in Ground Water

The reactive transport of U(VI) in a well-characterized shallow alluvial aquifer at a former U(VI) mill located near Naturita, CO, was predicted for comparative purposes using a surface complexation model (SCM) and a constant K _d approach to simulate U(VI) adsorption. The ground water at the site had U(VI) concentrations that ranged from 0.01 to 20 μM, alkalinities that ranged from 2.5 to 18 meq/L, and a nearly constant pH of 7.1. The SCM used to simulate U(VI) adsorption was previously determined independently using laboratory batch adsorption experiments. Simulations obtained using the SCM approach were compared with simulations that used a constant K _d approach to simulate adsorption using previously determined site-specific K _d values. In both cases, the ground water flow and transport models used a conceptual model that was previously calibrated to a chloride plume present at the site. Simulations with the SCM approach demonstrated that the retardation factor varied temporally and spatially because of the differential transport of alkalinity and dissolved U(VI) and the nonlinearity of the U(VI) adsorption. The SCM model also simulated a prolonged slow decline in U(VI) concentration, which was not simulated using a constant K _d model. Simulations using the SCM approach and the constant K _d approach were similar after 20 years of transport but diverged significantly after 60 years. The simulations demonstrate the need for site-specific geochemical information on U(VI) adsorption to produce credible simulations of future transport.     

Perfluorinated nanocomposite membranes modified by polyaniline: Electrotransport phenomena and morphology

This work summarizes results on the modification of perfluorinated sulfocationic membranes MF-4SC by in situ chemical polymerization of aniline. The investigation of transport properties of polyaniline/MF-4SC composite membranes after bulk modification - conductivity, diffusion and electroosmotic permeability, proton permselectivity - as well as porosimetry and polarization behavior is carried out as functions of aniline polymerization parameters and acid concentration. The fibrous-cluster model of a composite membrane is proposed for the estimation of transport and structural parameters, taking into account different mechanism of charge transfer in structural fragments of the composite. The atomic force microscopy images and curves of water distribution on the effective pore radii in the composite membranes testify to a morphological transition from the nano- to the microsize of polyaniline inclusions with increasing the aniline polymerization time. This effect is confirmed by the analysis of two-phase model transport and structural parameters. High values of the “true” proton transport numbers of composites are obtained and discussed. The dynamic hydration numbers of protons and chloride co-ions are estimated using the “true” transport numbers of protons and the electroosmotic coefficients of composites. The current-voltage curves of composite membranes in the “free standing” state after bulk and surface modification by polyaniline are investigated. The effect of stabilization of limiting current density is observed for MF-4SC membrane after bulk modification. The effect of current-voltage curves asymmetry is observed for different orientation of the polyaniline layer towards the current direction for an anisotropic composite membrane after surface modification.     

长距离气力输送系统与应用

气力输送虽然在许多领域中被广泛应用，如煤炭、粮食等，但其理论计算尚不够完善，许多计算公式还依赖试验数据。位于上海市浦东外高桥的上海海洋钻井工程公司，是东海油气勘探开发的重要基地。为东海油气勘探开发而建的气力输送油井水泥和钻井泥浆材料系统装置经过几个月生产运行，证明该系统装置运行安全可靠，集储存、于混、输送于一体，是目前国内外石油行业输送距离最长、技术水平先进、设备配置较好的气力输送系统。     

钢铁企业改造中总图运输设计问题探讨

针对马钢将要开展的"十二五"技术改造项目,从公司现状存在的问题着手,就后续工程总图运输专业设计中要考虑的问题进行探讨,并提出自己的看法。     

EXPERIMENTAL STUDY ON BED-LOAD SEDIMENT TRANSPORT IN IRREGULAR WAVE-CURRENT COEXISTENT FIELD

1.　INTRODUCTIONTheproblemofsedimenttransportnearcoastalregionisofgreatimportanceforthesiltationinnavigationalfairways,harbordocksandthechangesinbeachprofileandcoastalmorphology.Underpracticalconditions,dynamicenvironmentisverycomplexbecausethewaveandcurrentarerandomand,theirpropagatingdirectionsarealsouncertain.Sothestudyofsedimenttransportinanirregularwave-currentcoexistentfieldismoreimportantthanthatinpurewaveorpurecurrentfield.Inrecentyears,manyempiricalformulaswereproposedtoexpressth…     

Prediction of Sediment Load Concentration in Rivers using Artificial Neural Network Model

An artificial neural model is used to estimate the natural sediment discharge in rivers in terms of sediment concentration. This is achieved by training the network to extrapolate several natural streams data collected from reliable sources. The selection of water and sediment variables used in the model is based on the prior knowledge of the conventional analyses, based on the dynamic laws of flow and sediment. Choosing an appropriate neural network structure and providing field data to that network for training purpose are addressed by using a constructive back-propagation algorithm. The model parameters, as well as fluvial variables, are extensively investigated in order to get the most accurate results. In verification, the estimated sediment concentration values agree well with the measured ones. The model is evaluated by applying it to other groups of data from different rivers. In general, the new approach gives better results compared to several commonly used formulas of sediment discharge.     

非稳定流条件下非饱和均质土壤溶质运移的传递函数解

根据溶质运移的传递函数模型Tromsfer Function Model, TFM理论，研究了非稳定流条件下非饱和均质土壤中表施和原有NO-3 N及原有Cl-的运移。由极大似然法估算了模型参数μ和σ2，求出了溶质运移的概率密度函数，计算了NO-3 -N的淋失量，并利用土壤中原有Cl-的动态，对NO-3 N的迁移过程进行了模拟，同时还估算了溶质的中值迁移时间tm和均值迁移时间相应的运移体积θst和θst。     

促进传递型支撑液膜分离有机溶剂的研究进展

促进传递型支撑液膜 (FTSLM )具有高通量和高选择性的特点 ,对分离废液、废气中的少量污染性有机物有独特的优势。概述了FTSLM的特点和促进传递的基本原理 ,介绍了FTSLM在有机物分离领域中的应用 ,讨论了制约FTSLM工业化应用的瓶颈问题和解决途径 ,展望FTSLM的发展和未来的研究趋势。指出FTSLM和其它膜过程结合 ,如渗透汽化或蒸汽渗透等 ,能够强化有机物分离过程