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11.
Gitae Moon Intae Son Chunho Kim Chi Hyeong Cho Eunbi Lee Eun Hyoung Bae 《Molecular Crystals and Liquid Crystals》2019,687(1):60-67
AbstractTo enable recent 3D and moving picture applications, liquid crystal displays (LCD) must exhibit fast response and wide viewing angle characteristics. Pre-tilted vertical alignment layers for high-speed LCD were fabricated using bi-functional photoreactive monomers. The monomers can be confined to the polyimide layer and photo-polymerized by UV exposure under voltage. Response characteristics of photo-controlled alignment films according to the structure were investigated. Vertical alignment properties were evaluated using a polarizing optical microscope, and electro-optical characteristics were compared through the voltage-transmittance curve and response time measurement. Faster response speed could be obtained by using photoreactive monomers having a long alkyl chain. 相似文献
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Z. Hadjou Bélaid S. Ben Mansour D. Boroguiaa A. Boubris L. Benhabib F. Z. Benkhaled 《Journal of Macromolecular Science: Physics》2020,59(11):686-696
AbstractThis work examines the development and characterization of tripropylene glycol di-acrylate/liquid crystal E7 (TPGDA/LC E7) PDLCs composite materials (polymer-dispersed-liquid-crystals). These systems were produced by UV irradiation photopolymerization (PIPS) of a mixture of the monomer tripropylene glycol di-acrylate (TPGDA) and the liquid crystal E7 (LC E7, a mixture of three cyano-biphenyl and one cyano-terphenyl LCs), in the presence of 2?wt% (of the acrylate/E7 mixture) of a photoinitiator. Electro-optical, thermal and optical characterization was used to understand the effect of the LC concentration on the electro-optical and thermo-physical properties of these materials. Polarizing optical microscopy (POM) and differential scanning calorimetry (DSC) studies were performed to observe the system morphology and to determine the transition temperatures of these materials, both as a function of their composition. The findings showed a slight variation of the nematic-isotropic transition temperature, TNI, of the LC E7 and of the glass transition temperature, Tg, of the TPGDA polymeric matrix as a function of the mass percentage of the LC E7. A very good electro-optical response for the composition 30/70?wt % TPGDA/LC E7 was obtained. 相似文献
14.
This paper develops a modified smoothed particle hydrodynamics (SPH) method to model the coalescence of colliding non-Newtonian liquid droplets. In the present SPH, a van der Waals (vdW) equation of state is particularly used to represent the gas-to-liquid phase transition similar to that of a real fluid. To remove the unphysical behavior of the particle clustering, also known as tensile instability, an optimized particle shifting technique is implemented in the simulations. To validate the numerical method, the formation of a Newtonian vdW droplet is first tested, and it clearly demonstrates that the tensile instability can be effectively removed. The method is then extended to simulate the head-on binary collision of vdW liquid droplets. Both Newtonian and non-Newtonian fluid flows are considered. The effect of Reynolds number on the coalescence process of droplets is analyzed. It is observed that the time up to the completion of the first oscillation period does not always increase as the Reynolds number increases. Results for the off-center binary collision of non-Newtonian vdW liquid droplets are lastly presented. All the results enrich the simulations of the droplet dynamics and deepen understandings of flow physics. Also, the present SPH is able to model the coalescence of colliding non-Newtonian liquid droplets without tensile instability. 相似文献
15.
《Journal of separation science》2018,41(6):1319-1337
The present review discusses the theory and application of van't Hoff analysis in chiral chromatography, with main focus on liquid chromatography. The topics considered include the physical meaning of van't Hoff equation's parameters, interpretation of thermodynamic data in terms of retention and enantioseparation mechanisms, abnormal behavior of van't Hoff plots, and best practices to avoid biased results. 相似文献
16.
Dr. Si-Yong Qin Yan Jiang Dr. Han Sun Han Liu Prof. Ai-Qing Zhang Prof. Xinxiang Lei 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(39):17245-17251
Residual dipolar coupling (RDC), a robust anisotropic NMR parameter for structural elucidation of organic molecules, is only accessible in an anisotropic environment. Herein, we introduce a novel alignment medium based on the molecular self-assembly of oligopeptide amphiphile (OPA). This medium is compatible with different intermediate and polar solvent systems, such as CD3OD, [D6]DMSO, and D2O. The preparation of the OPA-based medium is simple and rapid, while only very weak background signals were observed from OPAs. Furthermore, we show that the purity of OPA has only a minor influence on the quality of the RDC data. These advantages allow RDC measurements of organic molecules with different polarities and solubilities with high efficiency and accuracy. 相似文献
17.
ABSTRACTWe study the molecular-scale features of the solid surface that result in the spontaneous motion of a nanodroplet due to the periodic variation of temperature. We first employ a thermodynamic model to predict the variation of solid–fluid interfacial properties that can result in the above motion. The model identifies a composite (surface couple) made of two surfaces that are characterised by a large difference between the entropic parts of the solid–liquid interfacial free energies. In order to understand the molecular-scale features of the two surfaces that may form a surface couple, we performed grand canonical Monte Carlo simulations of Lennard Jones fluid and crystalline surfaces made of Lennard Jones-like atoms. We then used the cumulant expansions of the perturbation formulas to divide the interfacial entropy into two parts: The one that is directly affected by the solid–fluid attraction (direct part), and the other (indirect part) that is indirectly affected by the solid–fluid attraction via the alteration of interfacial fluctuations. Our results indicate that two surfaces form a surface couple if the differences between their chemical natures lead to large differences in the indirect part of the interfacial entropy, while the direct part remains relatively unaffected. 相似文献
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19.
Xiaofeng Zheng Xinyu Zhao Jie Huang Hao Yang Qinghui Wang Yuhang Liu Peiwei Gong Laijin Tian Hongping Xiao Zhe Liu 《应用有机金属化学》2020,34(12):e5981
The low-cost, high specific surface area and porosity, controlled pore size, and chemical properties of metal–organic framework (MOF) materials have attracted much attention in the exploration of proton conduction. The method of chemically modifying MOF structures or introducing conductive medium into the holes can effectively improve the proton conductivities of the materials. Here, the structural tunability of ionic liquid (IL) and flexible MOF (fle-MOF) materials are matched to give full play to the conductivity of IL, the framework support, and the microporous effect of MOFs, which achieves the synergistic effect of performance and expands the temperature range of proton transfer. Three kinds of CS/IL@fle-MOF membranes were prepared by combining three fle-MOFs with 1-carboxymethyl-3-methylimidazole (CMMIM) in different proportions to obtain 15 pieces of membranes. The comparative analyses show that CS/IL@fle-MOF membranes have excellent proton conduction performance at a wider temperature range (263–353 K) and lower relative humidity (75% RH). Among them, the proton conductivities of CS/CMMIM@MIL-88A-25% and CS/CMMIM@MIL-88B-125% are up to 1.33 and 1.42 S cm−1 at 75% RH and 353 K, respectively; whereas those of CS/CMMIM@MIL-53(Fe)-75% and CS/CMMIM@MIL-88B-125% reach up to 2.1 × 10−3 and 1.28 × 10−3 S cm−1 at 75% RH and 263 K, respectively. The Ea of CS/CMMIM@fle-MOFs is in the range of 0.1–0.5 eV, suggesting that the proton transport follows predominantly the typical Grotthuss transfer mechanism. The results of this study indicate that the CS/CMMIM@fle-MOF membranes combinations offer great potential for the design of composite porous proton-conducting materials. 相似文献
20.
Ziritaxestat is a first-in-class autotoxin inhibitor. The purpose of this study was to develop a liquid chromatography/electrospray ionization tandem mass spectrometric (LC–MS/MS) method for the determination of ziritaxestat in rat plasma. The plasma sample was deproteinated using acetonitrile and then separated on an Acquity BEH C18 column with water containing 0.1% formic acid and acetonitrile as mobile phase, which was delivered at 0.4 ml/min. Ziritaxestat and the internal standard (crizotinib) were quantitatively monitored with precursor-to-product transitions of m/z 589.3 > 262.2 and m/z 450.1 > 260.2, respectively. The total running time was 2.5 min. The method showed excellent linearity over the concentration range 0.5–2000 ng/ml, with correlation coefficient >0.9987. The extraction recovery was >82.09% and the matrix effect was not significant. Inter- and intra-day precisions (RSD) were <11.20% and accuracies were in the range of −8.50–7.45%. Ziritaxestat was demonstrated to be stable in rat plasma under the tested conditions. The validated LC–MS/MS method was successfully applied to study the pharmacokinetic profiles of ziritaxestat in rat plasma after intravenous and oral administration. Pharmacokinetic results demonstrated that ziritaxestat displayed a short half-life (~3 h) and low bioavailability (20.52%). 相似文献