3D‐morphology reconstruction of nanoscale phase‐separation in polymer memory blends

In many organic electronic devices functionality is achieved by blending two or more materials, typically polymers or molecules, with distinctly different optical or electrical properties in a single film. The local scale morphology of such blends is vital for the device performance. Here, a simple approach to study the full 3D morphology of phase‐separated blends, taking advantage of the possibility to selectively dissolve the different components is introduced. This method is applied in combination with AFM to investigate a blend of a semiconducting and ferroelectric polymer typically used as active layer in organic ferroelectric resistive switches. It is found that the blend consists of a ferroelectric matrix with three types of embedded semiconductor domains and a thin wetting layer at the bottom electrode. Statistical analysis of the obtained images excludes the presence of a fourth type of domains. The criteria for the applicability of the presented technique are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1231–1237     

煤直接液化油中混合酚的分离研究

利用分子筛择形特点，对煤直接液化油中的混合酚实施高效分离。本研究选取间甲酚和对甲酚作为分离煤直接液化油馏分段混合酚的模型化合物，采用化学液相沉积法对HZSM-5吸附剂的孔口结构进行改变，分析分子筛硅铝比及颗粒粒径对模型化合物间甲酚和对甲酚吸附分离性能的影响，以获得高性能固相吸附剂，并将其应用于180-190℃馏分段混合酚分离。结果表明，当分子筛硅铝比为25、粒径为3-5 μm时，分子筛的孔口结构调节效果最优；当正硅酸乙酯的最小用量为0.2 mL/g时，固相吸附剂的吸附量为0.03 g/g，对甲酚选择性高于95%。由于外表面沉积物对吸附剂的孔口结构变化，导致对甲酚选择性的提高。进一步采用HZSM-5（1）吸附剂对真实煤直接液化油混合酚的分离中发现，苯酚和对甲酚的选择性均达到100%。     

Formation of porous polymer morphology by microsyneresis during divinylbenzene polymerization

This article describes the investigation of the importance of various reaction conditions on microsyneretic pore formation during polymerization of divinylbenzene (DVB) under so‐called “solvothermal” conditions. To induce microsyneretic pore formation, the most important parameter is an unusually high dilution of monomers with a “good” porogen solvating the polymer chains. High dilution and solvation of the growing poly(DVB) chains promote the prolongation of the polymer chains rather than their interconnection by crosslinking. Consequently, when the polymer gel density reaches the point where syneresis starts, the polymer network is geometrically too extensive to be broken up into precipitating entities and, instead, porogen droplets are formed within the continuous polymer gel. The pore geometry created by microsyneresis offers high surface area in wide mesopores and hence, high capacity for supporting functional groups or reactions with much better accessibility than narrow pores between polymer microspheres produced by macrosyneresis in conventional styrenic polymer supports. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 774–781     

Crosslinked poly(ethylene oxide) containing siloxanes fabricated through thiol‐ene photochemistry

Homogenous amphiphilic crosslinked polymer films comprising of poly(ethylene oxide) and polysiloxane were synthesized utilizing thiol‐ene “ click ” photochemistry. A systematic variation in polymer composition was Carried out to obtain high quality films with varied amount of siloxane and poly(ethylene oxide). These films showed improved gas separation performance with high gas permeabilities with good CO₂/N₂ selectivity. Furthermore, the resulting films were also tested for its biocompatibility, as a carrier media which allow human adult mesenchymal stem cells to retain their capacity for osteoblastic differentiation after transplantation. The obtained crosslinked films were characterized using differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis, FTIR, Raman‐IR , and small angle X‐ray scattering. The synthesis ease and commercial availability of the starting materials suggests that these new crosslinked polymer networks could find applications in wide range of applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1548–1557     

应力对M-Z型InP/InGaAsP-EAM偏振

采用Agilent 81910A光子全参量测试仪,首次实验研究了InP/In1－xGaxAs1－yPy-MQW（Multiple-Quantum-Well,MQW）材料与衬底间因应力而产生的M-Z型光调制器的PDL影响以及由此引起的由差分群时延(Differential Group Delay,DGD)表征的偏振模色散(Polarization Mode Dispersion,PMD).研究结果表明,半导体MQW光调制器的PDL与DGD是一致的.因此在半导体光器件的制作过程中,应尽可能地减小衬底与波导芯层之间的因残存应力的存在造成对光器件的高速性能的不利影响.     

Roles of SiH4 and SiF4 in growth and structural changes of poly-Si films

The structural properties of polycrystalline silicon films, prepared by plasma enhanced chemical vapor deposition system, with different flow rates of SiH₄/SiF₄ mixtures at 300 °C were investigated. This study indicates that the low hydrogen coverage on the growing surface, under optimum fluorine radicals, will be leaded to an improvement of crystallized area as compared with case of high hydrogen coverage surface. Moreover, the studies of the role of SiH₄ and SiF₄ radicals show that the SiH₄ radicals are important in the nucleation and growth of grains. However, SiF₄ radicals are effective in the structural change of grain boundaries regions and by this way, in the present system, establish the growth of grains under the dominant 〈1 1 0〉 direction. The stress investigation indicates that addition of high flow rate of SiF₄ in amorphous film, results in the nearly stress free films. Finally, we found that the changes in g-value reflect the changes in the intrinsic compressive and tensile stress in the both polycrystalline and amorphous silicon films.     

Economic Equilibrium: Optimality and Price Decentralization

Mathematical economics has a long history and covers many interdisciplinary areas between mathematics and economics. At its center lies the theory of market equilibrium. The purpose of this expository article is to introduce mathematicians to price decentralization in general equilibrium theory. In particular, it concentrates on the role of positivity in the theory of convex economic analysis and the role of normal cones in the theory of non-convex economies.     

Capillary Electrophoresis Chiral Separation for Enantiomeric Purity Determination of a Basic Drug in Pharmaceutical Formulations

Capillary electrophoresis using a running buffer composed of β-cyclodextrin as the chiral selector and ethanolamine mesylate at pH 9.6 is being used to monitor the stereochemical stability of a hydrophobic drug, containing two chiral centers, in two different formulated self-emulsifying drug delivery system (SEDDS) products. The separation takes place in less than 25 min. Strategies for enhancing the method reproducibility and detection sensitivity in the lower potency formulation are presented. The results demonstrating the specificity, assay precision, recovery, linearity and range achieved during the method validation experiments are presented in this paper.Presented at: CE in the Biotechnology and Pharmaceutical Industries: 7th Symposium on the Practical Applications for the Analysis of Proteins, Nucleotides and Small Molecules, Montreal, Canada, August 12–16, 2005.     

The influence of pulse duration on the stress levels in ablation of ceramics: A finite element study

We present a finite element model to investigate the dynamic thermal and mechanical response of ceramic materials to pulsed infrared radiation. The model was applied to the specific problem of determining the influence of the pulse duration on the stress levels reached in human dental enamel irradiated by a CO₂ laser at 10.6 μm with pulse durations between 0.1 and 100 μs and sub-ablative fluence. Our results indicate that short pulses with durations much larger than the characteristic acoustic relaxation time of the material can still cause high stress transients at the irradiated site, and indicate that pulse durations of the order of 10 μs may be more adequate both for enamel surface modification and for ablation than pulse durations up to 1 μs. The model presented here can easily be modified to investigate the dynamic response of ceramic materials to mid-infrared radiation and help determine optimal pulse durations for specific procedures.