Effects of the H-bond donor structure on the properties of supramolecular side chain liquid crystalline polymers based on poly(3-carboxypropylmethylsiloxane-co-dimethylsiloxane)s and stilbazoles

Supramolecular side chain liquid crystalline polymers (SCLCPs) based on poly(3-carboxypropylmethylsiloxane-co-dimethylsiloxane) (PSIX, X=100, 76, 60, 41 or 23, denoting the mole percentage of 3-carboxypropylmethylsiloxane unit in the polymer) and stilbazole derivatives have been obtained through intermolecular hydrogen bonding (H-bonding) interactions between the carboxylic acid and the pyridyl moieties. The formation of H-bonding and self-assembly results in the formation of new mesogenic units, in which H-bonds function as molecular connectors. FTIR shows the existence of H-bonding in the complexes. The polymeric complexes behave as single component liquid crystalline polymers and exhibit stable and enantiotropic mesophases. The liquid crystalline properties of the supramolecular SCLCPs were studied using differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction, and were found to exhibit smectic A phases with focal-conic textures. The thermal stability of the SCLCP increases on increasing the carboxylic acid content in the polysiloxane and the concentration of the stilbazole derivative in the complex. However, the thermal stability decreases on increasing the chain length of the stilbazole derivative. The crystal phase was not formed even on cooling to the glass transition temperature of the polymeric complex.     

Apparatus for High-Resolution Solid Hydrogen Matrix Isolation Spectroscopy and Its Application

Apparatus integrating a Fourier transform-infrared (FT-IR) spectrometer and a mid-infrared difference frequency generation (DFG) laser spectrometer was built for the study of the matrix isolation spectrum in solid molecular hydrogen. A 3-cm-long molecular hydrogen crystal was grown in a liquid-helium Dewar, and its infrared absorption spectrum in the 1-5 μm region was recorded to test the system. The W₀(0) (ν=0←0, J=6←0) line around 2410 cm⁻¹ of solid hydrogen was investigated with the DFG laser spectroscopy. High-resolution matrix isolation spectrum of CO² co-deposited with hydrogen on a BaF₂ cold plate at liquid-helium temperature was studied.     

Synthesis of some chiral liquid crystals and study of the effect of intramolecular hydrogen bonding on the phase behaviour

The synthesis of three new series of chiral Schiff's bases containing benzilideneaniline and 2-hydroxybenzilideneaniline moieties as mesogenic cores is presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurements were used to study the phase transition temperatures and behaviour. The results reveal that most of these materials show chiral smectic mesomorphism.     

Synthesis and transition temperatures of liquid crystals incorporating a 1,4-tetrafluorophenylene unit

Two homologous series of mesogenic materials which incorporate a 1,4-tetrafluorophenylene moiety and a terminal cyano- or nitro-substituent have been synthesized by using palladiumcatalysed coupling procedures. The compounds exhibit nematic and/or smectic A phases.     

四个麦芽品质性状的杂种优势和相关分析

本文对四个主要麦芽品质性状—a一淀粉酶活力、麦芽汁粘度、麦芽汁色度和搪化力进行了杂种优势和相关分析.(1)相对优势结果表明，在84个组合次中，呈正向优势的46个，占54.76男，负向优势34个，占40.48男，无显性4个，占4.75男;(2)四个品质性状的中亲优势平均值分别为一6.117、一9.965 40.452和一。.545s a-淀粉酶活力和糖化力的超高亲优势分别为一14.578和一8.201,麦芽汁粘度和色度的超低亲优势分别为5.442和70.455.四个性状杂种优势的变异系数均很大.(3)麦芽汁色度的F，对MP的回归系数(B)和相关系数(r)均达显著水平，分别为。..43和0.50，麦芽汁粘度的相关系数达显著水平，为一。.45,其余均未达显著水平，(4)除麦芽汁色度性状外，另三个性状的中亲优势、超亲优势和特殊配合力的相关均达显著或极显著水平.(5)四个麦芽品质性状间的相关结果表明，仅有a-淀粉酶活力和麦芽汁粘度间呈极显著负相关(r=一0.56').最后，文章根据实验结果，就啤酒大麦麦芽品质改良的遗传育种及其杂种优势应用进行了初步讨论.     

EXISTENCE OF GLOBAL SMOOTH SOLUTION FOR SCALAR CONSERVATION LAWS WITH DEGENERATE VISCOSITY IN 2-DIMENSIONAL SPACE

This article concerns the existence of global smooth solution for scalar conservation laws with degenerate viscosity in 2-dimensional space. The analysis is based on successive approximation and maximum principle.     

Growth of single-crystal magnetite nanowires from Fe3O4 nanoparticles in a surfactant-free hydrothermal process

Single-crystal magnetite nanowires with average diameter of ca. 20 nm and length of up to several micrometers were prepared by a simple alkaline surfactant-free hydrothermal process. The crystallinity, purity, morphology, and structural features of the as-prepared magnetite nanowires were investigated by powder X-ray diffraction, transmission electron microscopy (TEM) and selected area electron diffraction. The composition and length of nanowires depends on the pH, with higher pH favoring longer nanowires composed entirely of Fe₃O₄. A mechanism for nanowire growth is proposed.     

测定透镜厚度新法及其误差探讨

本文介绍利用景深短、高倍率、大口径的物镜，采用光学方法，对被测透镜上下表面调焦，从而测定其中心厚度的一种新方法，并对测量误差进行了探讨。     

卡尔曼滤波紫外光度法同时测定酱油、食醋中的山梨酸和苯甲酸

在酸性条件下，采用乙酸乙酯萃取、Na2HPO4溶液反萃取分离酱汪、食醋中的山梨酸、苯甲酸，卡尔曼滤波法计算结果，并与比值导数波谱法进行比较。结果表明，卡尔曼滤波法较地数波谱法有较高准确度和精密度，并能监测干扰物质存在与否。用于实际样品分析有更高的可靠性。     

Synthesis for robust synchronization of chaotic systems under output feedback control with multiple random delays

Synchronization under output feedback control with multiple random time delays is studied, using the paradigm in nonlinear physics—Chua’s circuit. Compared with other synchronization control methods, output feedback control with multiple random delay is superior for a realistic synchronization application to secure communications. Sufficient condition for global stability of delay-dependent synchronization is established based on the LMI technique. Numerical simulations fully support the analytical approach, in spite of the random delays.