Influence of different nematic crosslinking unit on mesomorphism of side-chain cholesteric elastomers containing menthyl groups

The synthesis of two cholesteric monomers (M₁ and M₂), nematic crosslinking agent (C₁ and C₂), and the corresponding side-chain elastomers containing menthyl groups (P₁ and P₂ series) is described. The mesomorphism was investigated by differential scanning calorimetry, polarizing optical microscopy, X-ray diffraction, and thermogravimetric analysis. The effect of the content of the different nematic crosslinking unit on the mesomorphism of the elastomers was discussed. M₁ and M₂ showed cholesteric and blue phases; C₁ and C₂ showed nematic phase. Because of the introduction of the nematic crosslinking unit, elastomers P_1-1−P_1-5 and P_2-1−P_2-5 exhibited cholesteric phase. With increasing the content of nematic crosslinking unit, T _g of the obtained elastomers revealed an increased tendency, and T _i of P₁ series firstly increased then decreased, while T _i of P₂ series decreased the mesomorphism of the corresponding elastomers when the content of nematic crosslinking unit was 12 mol.%.     

新型花状纳米四氧化三钴修饰玻碳电极对芦丁的电催化氧化及其测定

采用滴涂法制备了新型花状纳米Co3O4修饰玻碳电极(F-Co3O4-np/GC/CME).纳米Co3O4的扫描电镜(SEM)表明,纳米Co3O4膜为多孔纳米材料;X-射线衍射光谱(XRD)表明,纳米Co3O4为纯面心立方相尖晶石结构.采用循环伏安法(CV)、计时电量法(CC)、半微分线性伏安法(SDV)研究了芦丁在F-Co3O4-np/GC/CME上的电化学行为及动力学性质.结果表明:芦丁在此修饰电极上有敏锐的氧化还原峰,其氧化峰电流与电位扫描速度(v)呈良好线性关系,表明芦丁在修饰电极上的伏安行为受吸附控制.芦丁的氧化峰电流与其浓度在1.0×10-6～4.5×10-4 mol/L范围内呈线性关系;检出限为5.0×10-7 mol/L.本方法可用于槐花、红花、金银花、杜仲叶的提取液中芦丁含量的测定,加标回收率为99.5%～100.9%之间;RSD为1.7%～4.5%.     

黄金蝉若虫体蛋白水解液的荧光标记及电喷雾质谱鉴定

采用2-[2-(7H-二苯并[a,g]咔唑-乙氧基)-乙基]氯甲酸酯(DBCEC-Cl)作为柱前衍生试剂, 于室温下,在硼酸钠缓冲液(pH 9.0)中,金蝉若虫体蛋白水解液中氨基酸的完全衍生化在5 min即可完成.在Hypersil BDS C18色谱柱 (200 mm×4.6 mm, 5 μm) 上, 采用梯度洗脱实现了各衍生物的完全基线分离.最佳荧光检测为λex/λem=300/395 nm.在线串联的ESI/MS正离子质谱数据显示:所有衍生物均给出m/z 338 5,294.5的特征碎片离子峰.荧光条件下的线性回归系数大于0.9992; 检出限为2.6～24 fmol.本方法灵敏、可靠、重现性好.对实际黄金蝉若虫体蛋白水解液中氨基酸的测定,结果满意.     

Determination of Fatty Acids (C1 – C10) from Bryophytes and Pteridophytes

A simple and mild method for the determination of fatty acids (C₁ – C₁₀) based on a condensation reaction using 7-aminonaphthalene-1,3-disulfonic acid (ANDSA) as labeling reagent with capillary zone electrophoresis has been developed. The detection was performed with a diode array detector at 254 nm. A 58.5 cm × 50 μm i.d. (50 cm effective length) untreated fused-silica capillary was used. To optimize the separation conditions, the background electrolyte concentration, column temperature, voltage and other factors were evaluated. The optimal separation conditions were as follows: 30 mmol L⁻¹ borate buffer (pH 9.5), 15 mmol L⁻¹ β-CD, temperature at 20 °C, pressure 50 mbar and injection time 8 s. Under the established conditions, 10 fatty acid derivatives could be well-separated within 17 min. The linearity was in the range of 0.07–5.0 μmol L⁻¹. Detection limits (at a signal-to-noise ratio of 3) were in the range of 0.027–0.042 μmol L⁻¹. The fatty acids from the extracted Funaria Hedw. and Selaginella samples were determined with satisfactory results.

     

液面微幅波动的激光干涉测量

对于低频微幅的液面波动,提出了一种激光干涉测量方法.实验上观察到了清晰、稳定的激光干涉图样.干涉图样受到调制,光强在两边界位置达到极大,形成两个极亮条纹.干涉条纹被限制在两个极亮条纹之间的确定区域内.根据光干涉理论推导出了调制干涉条纹光强度、相邻条纹角宽度、干涉区域角宽度与液面波物理参量之间的解析关系,该理论分析与实验...     

基于光纤布拉格光栅的智能服装人体测温模型研究

根据热量传递机理建立了智能服装中光纤布拉格光栅人体测温的热传递物理模型,对人体、空气层和服装之间的热传递进行了有限元建模和稳态热分析,确定了智能服装中光纤布拉格光栅温度场的数学模型,利用该数学模型对光纤布拉格光栅测量温度值进行了修正.在多点加权皮肤平均温度的基础上,提出了由左右胸、左右腋和后背五处皮肤温度构成的智能服装...     

Superconductivities and structural properties of ternary Tiben Zrben Ta alloys

Superconductivities and structural properties of Ti-Zr-Ta ternary alloys are extensively investigated. The TiZrTa sample has a cubic structure (β -phase) and shows a sharp superconducting transition at a critical temperature (T_c) of about 7.3 K. In addition, two series of Ti-Zr-Ta alloys, with nominal compositions of Ti_65-xZr₃₅Ta_x and Ti_xZr_65-xTa₃₅ respectively, are prepared, and their superconductivities and crystal structures change regularly with the chemical composition. Our experimental study also indicates that the annealing processing of this kind of material can cause the transition temperature to increase and the highest T_c is observed to be about 8.3 K in annealed samples.     

Improved charge trapping flash device with Al2O3/HfSiO stack as blocking layer

In this paper, we investigate an Al₂O₃/HfSiO stack as the blocking layer of a metal-oxide-nitride-oxide-silicon-type (MONOS) memory capacitor. Compared with a memory capacitor with a single HfSiO layer as the blocking layer or an Al₂O₃/HfO₂ stack as the blocking layer, the sample with the Al₂O₃/HfSiO stack as the blocking layer shows high program/erase (P/E) speed and good data retention characteristics. These improved performances can be explained by energy band engineering. The experimental results demonstrate that the memory device with an Al₂O₃/HfSiO stack as the blocking layer has great potential for further high-performance nonvolatile memory applications.     

用光学干涉法测量材料的高温线膨胀系数

采用石英传递杆将高温区材料的线膨胀量传递到室温区,并利用标准件进行标定的方法消除由传递带来的附加线膨胀量的影响,利用迈克耳孙干涉仪测量微小位移的原理,测量材料的线膨胀系数;测量相对误差仅为1.0％,而且测量过程非常直观简单.     

基于SBS光限幅和金属酞菁光限幅相结合的复合型光限幅器的研究

为了使受激布里渊散射(SBS)光限幅器的输出能量更"平",提出了一种基于SBS光限幅和金属酞菁光限幅相结合的复合型光限幅器的方案,即SBS光限幅后边放置金属酞菁光限幅,在两种光限幅器的共同限幅作用下,使复合型光限幅器的输出光能量更"平". 数值模拟了该复合型光限幅器的输出光能量随入射光强度的变化曲线,并在Countinuum's Nd: YAG种子注入式激光器中进行了实验验证. 理论和实验结果均表明,复合型光限幅器的输出光能量比单独SBS光限幅器更"平". 关键词： 复合型光限幅器 SBS光限幅 金属酞菁限幅