Influence of SMA content on the electro-optical properties of polymer-dispersed liquid crystal prepared by monodisperse poly(MMA-co-SMA)/LC microcapsules

Monodisperse poly(methyl methacrylate) (PMMA) particles containing various concentrations of stearyl methacrylate (SMA) were prepared, and a liquid crystal (LC) was swollen into the particles using a solute co-diffusion method (SCM). Phase separation behaviors between the polymer and LC were monitored by utilizing an optical and a polarized microscope (OM/POM). The monodisperse LC microcapsules were then applied to a polymer-dispersed liquid crystal (PDLC), and the electro-optical properties were investigated. As a result, the threshold and driving voltages were improved when the SMA content increased. The long alkyl chains of SMA in the capsules should exist at the interface of the LC and polymer resulting in an enhancement of phase separation between the polymer and LC, which largely influences the electro-optical properties of PDLC.     

Gasphasen-Reaktionen. 92. Thermische HCl-Abspaltung aus Alkyldichlorphosphanen (H3C/H)3C?PCl2 zu Phosphaalkenen (H3C/H)2CPCl und Phosphaalkinen (H3C/H)C≡P

Gasphase Reactions. 92 Thermal Elimination of HCl from Alkyldichlorophosphanes (H₃C/H)₃C? PCl₂ to Phosphaalkenes (H₃C/H)₂C?PCl and Phosphaalkines (H₃C/H)C≡P The alkyldichlorophosphanes H₃C? PCl₂, ClH₂? PCl₂, (H₃C)H₂C? PCl₂ and (H₃C)₂HC? PCl₂ split off HCl on heating in a gasflow under reduced pressure. PE spectroscopic gas analysis proves that under these conditions the short-lived phosphaalkenes H₂C?PCl, (H₃C)H₂C?PCl and – catalyzed by [MgCl₂? MgO/SiO₂]_∞ – (H₃C)₂C?PCl as well as the phosphaalkines HC≡P and (H₃C)C≡P are formed, all of which can be isolated by low temperature condensation. Based on the PES ionization patterns recorded and on the MNDO calculations for their assignment, the π_CP multiple bonds are discussed. The presumable pathway of the HCl elimination is rationalized for (H₃C)H₂C? PCl₂ by an approximate MNDO energy hypersurface.     

Synthesis, crystal structure and properties of the Cu complex of a tetradentate imidazole-functionalized diazamesocyclic ligand, 1,4-bis(N-1-methylimidazol-2-yl-methyl)-1,4-diazacycloheptane

A new potential tetradentate ligand, 1,4-bis(N-1-methylimidazol-2-ylmethyl)-1,4-diazacycloheptane (l), together with its Cu^II complex [CulCl]ClO₄ (1), has been reported. The crystal structure of 1, determined by single-crystal X-ray analysis, shows that it is in chiral P2₁2₁2₁ space group. The Cu^II centre is penta-coordinated in square pyramidal geometry and the diazacycloheptane (DACH) ring adopts normal boat configuration. The most striking feature of this complex is the formation of a 3D network bridged through the C-H?Cl hydrogen bonds with the perchlorate anions in the cavities, and stabilized via π-π stacking interactions along the a-direction. The solution behaviour of 1 has been further investigated by UV/Vis and ESR techniques.     

Effects of type and number of impellers and liquid viscosity on the power characteristics of mechanically agitated gas—liquid systems

Effect of the type and number of high-speed impellers installed on a common shaft on the power characteristics was investigated in water and glucose solutions of different concentration. Different configurations of the Rushton or Smith turbines, pitched blade turbines, propeller, and A 315 impeller were tested. Measurements of power consumption were carried out within the transitional and turbulent regime of the fluid flow using the strain gauge method. Baffled agitated vessels with inner diameter of 0.288 m and 0.634 m were used for the experiments. Liquid height in the vessels was equal to the vessel diameter or it was twice higher. The relative power consumption was compared for different configurations of the impellers. Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May 2006.     

Flammability studies of 3-methyl pyridine/water system

In industrial processes, information on the safety property of chemicals is essentially crucial for safe handling during unit operations. Ensuring the safe use of combustible or flammable substances in processes is unlikely without detailed investigations of their flammability characteristics and related hazards. We studied 3-methyl pyridine (3-picoline), e.g., flammability limits (LFL/UFL), maximum explosion pressure (P _max), maximum explosion pressure rise (dP/dt)_max, minimum oxygen concentration (MOC), vapor deflagration index (K _g), and characterized the influence of inert steam (H₂O) on critical parameters for 3-picoline/water mixtures at 270°C, 1 atm, various oxygen concentrations, and vapor mixing ratios (100/0, 30/70, 10/90 and 5/95 vol.%) with a 20-L-Apparatus in simulated conditions, respectively. The results showed that the flammability characteristics of 3-picoline_(aq) all increased with the oxygen concentration. However, as the composition of inert steam increased, the flammability parameters and the degree of fire and explosion hazards were significantly reduced, instead. This study elucidated the flammability properties of 3-picoline mixed with inert steam. The conclusions could be applied to proactively prevent the relevant processes from incurring fire and explosion accidents.     

煤加氢液化残渣的流变特性研究

采用从煤直接液化实验装置取得的液化残渣，研究了它的流变性及温度和油、沥青质、固体含量对其流变性的影响。液化残渣是剪切变稀的非牛顿型假塑性流体，非牛顿指数随温度升高而不断减小，温度越高越接近牛顿流体行为。液化残渣对温度非常敏感，在升温过程中其表观黏度下降很快，且没有出现黏度峰。在液化残渣中加入少量的循环油后其表观黏度大幅下降；而在加入少量沥青质后则表现出低温下黏度变大，高温下黏度变小的现象；固体含量则始终是黏度增大的因素，表明其黏度与油、沥青质和固体含量关系密切。液化残渣的黏度－温度关系符合Arrhenius关系式，但在升温过程中出现了拐点，低温段的黏流活化能比高温段的要大。     

Structures and electrochemical characteristics of several kinds of alloys

The structures and the electrochemical characteristics of La_0.7−x Ce_xMg_0.3Ni_2.8Co_0.5 (x = 0.1–0.5) alloy, Ti_0.25−x Zr_xV_0.35Cr_0.1Ni_0.3 (x = 0.05–0.15) alloy and AB_3<x<5-type alloy, which are the representative examples of AB₃-type alloy, solid solution alloy and non-AB₅-type alloy, respectively, have been investigated, and the performances of MH-Ni battery in which AB_3<x<5 type alloy is used as the negative electrode material are examined at relatively low temperature.     

Capillary gas chromatography of pesticide residues in foods: Application of a split/splitless inlet system

Residue mixtures of pesticides in foods which were difficult to separate by packed-column gas chromatography were determined by capillary gas chromatography and electron capture detection. Manual injections of sample and reference standard were made with a 10 μL syringe on a septum-enclosed, split/ splitless inlet system. Optimal peak height repeatability (± 3%( was achieved with three-μL injections which were made within time periods of four hours or less. The average linearity coefficient (slope( obtained for detector response as a function of solution concentration was 1.1.     

超临界流体萃取仪器的研制

本文报道了以国产原配件为基础，成功地研制了分析规模的超临界流体萃取仪器、并对仪器性能进行了全面考察，仪器性能稳定，重现性良好（ＲＳＤ＜３．１％），定量线性关系可靠，可满足定量萃取的要求。     

Darstellung und spektroskopische Charakterisierung von Carboxylatododecaboraten

Preparation and Spectroscopic Characterization of Carboxylatododecaborates The tetrabutylammonium salt (TBA)₂[B₁₂H₁₂]^2? reacts with formic, acetic, cyanoacetic, phenylacetic, propionic, butyric, and thioacetic acid at temperatures between 80 and 150°C forming the carboxylatododecaborates [(RC(O)O)_n? B₁₂H_{12? n}]^2?, n = 1, 2, [CH₃C(O)S? B₁₂H₁₁]^2?. The isolation of the pure compounds is achieved by ion exchange chromatography on diethylaminoethyl cellulose. In case of the dicarboxylatododecaborates beside the 1,7-isomer predominantly the 1,2-isomer, while 1,2-[(OH)C₆H₅CH₂C(O)O? B₁₂H₁₀]^2? is formed exclusively. The alcaline hydrolysis of [RC(O)O? B₁₂H₁₁]^2? and 1,2-[(OH)C₆H₅CH₂C(O)O? B₁₂H₁₀]^2? results in [(OH)? B₁₂H₁₁]^2? and 1,2-[(OH)₂? B₁₂H₁₀]^2?. All compounds are characterized by their ¹¹B-nmr, ¹³C-nmr and IR spectra. The ¹¹B-nmr signals are assigned by a sheme allowing to establish expected spectra.