Numerical simulation of mesoscopic mechanical behaviors of gradual multi-fiber-reinforced polymer matrix composites

To simulate the deformation and the fracture of gradual multi-fiber-reinforced matrix composites, a numerical simulation method for the mesoscopic mechanical behaviors was developed on the basis of the finite element and the Monte Carlo methods. The results indicate that the strength of a composite increases if the variability of statistical fiber strengths is decreased.

Determination of sulpiride by capillary electrophoresis with end-column electrogenerated chemiluminescence detection

Background: Capillary electrophoresis (CE) with tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)]-electro-generated chemiluminescence (ECL) detection is a promising method for clinical analysis. In this study, a method combining CE with Ru(bpy)(3)(2+) ECL (CE-ECL) detection that can be applied to amine-containing clinical species was developed, and the performance of CE-ECL as a quantitative method for determination of sulpiride in human plasma or urine was evaluated. Methods: Sulpiride was separated by capillary zone electrophoresis in uncoated fused-silica capillaries [510 cm x 25 mum (i.d.)] filled with phosphate buffer (pH 8.0 and a driving voltage of +15 kV, with end-column Ru(bpy)(3)(2+) ECL detection. A platinum disc electrode was used as working electrode. Sulpiride in human plasma or urine samples (100 muL) was extracted by a double-step liquid-liquid extraction procedure, dried under nitrogen at 35 degreesC in a water bath, and reconstituted with 100 muL of filtered water. The extraction solvent was ethyl acetate-dichloromethane (5:1 by volume). Results: Under optimum conditions (pH 8.0 phosphate buffer, injection for 6 s at 10 kV, and +1.2 V as detection potential), separation of sulpiride was accomplished within 4 min. The calibration curve was linear over a concentration range of 0.05-25.0 mumol/L, and the limit of detection was 2.9 x 10(-8) mol/L for sulpiride. Intra- and interday CVs for ECL intensities were <6%. Extraction recoveries of sulpiride were 95.6-101% with CVs of 2.9-6.0%. The method was,clinically validated for patient plasma and urine samples. Conclusions: CE combined with Ru(bpy)(3)(2+) ECL is reproducible, precise, selective, and enables the analysis of sulpiride in human plasma and urine. It thus is of value for rapid and efficient analysis of amine-containing analytes of clinical interest.

高倍率放电的低温金属氢化物电极研究

本文研究了稀土-镍基合金(MmNiAlCoMn)氢化物电极的电化学活化,倍率放电,自放电性能和荷电能力,以及室温至-40℃范围放电电流和温度对电化学放电容量的影响.结果表明:室温下稀土-镍基合金(MmNiAlCoMn)诸方面性能与市售AB<,5>型合金基本相同,但是,在低温范围(-30℃~40℃),稀土-镍基合金(MmNiAlCoMn)的大电流放电性能和放电容量,都优于市售AB<,5>型合金,是低温MH-Ni电池氢化物电极的侯选者.

Luminescence centers and valence change of Eu2+ in KCaF3

The nature of the emission centers and the valence change of Eu2+ in KCaF3:Eu2+ depends strongly on preparation conditions. Experimental results show that there are two different d-->f emission bands, located at 425 and 510 nm, respectively. Their origin, relationship, and the effect of doping concentration on them are discussed. A Eu2+-Eu3+ valence change process is proposed. (C) 2000 Elsevier Science Ltd. All rights reserved.

肌苷在玻碳电极上的伏安法研究

应用线性扫描伏安法（LSV），微分脉冲伏安法（DPV）和循环伏安法（CV）对肌苷在玻碳电极（GCE）上的阳级伏安行为进行了研究，发现在0．1mol/L磷酸氢二纳溶液中，于1．42V（vs.Ag／AgCl）左右产生一个阳极氧化峰，峰电流与肌苷浓度在5×10-4～8×10-2g/L范围内呈线性关系，峰电位随溶液pH值增加而降低。肌苷在与次黄嘌呤、黄嘌呤、尿酸共存时，可得4个分辨良好的阳极氧化峰，它们的峰电位分别为1．42V、1．07V、0．72V和0．26V。用本法不需分离直接测定了药物针剂和加标尿样。实验结果表明肌苷的电极反应为扩散控制不可逆过程。

Electrochemical and spectroscopic study of vitamin D-2 by in situ thin layer CD spectroelectrochemistry

The electrooxidation of vitamin D-2 (VD2) was studied by cyclic voltammetry and in situ circular dichroic (CD) spectroelectrochemistry for the first time, The mechanism of electrooxidation and some useful kinetic and adsorption parameters were obtained. The results showed that the oxidation of VD2 in ethanol solution is an irreversible diffusion controlled process following a weak adsorption of the electroinactive product at a glassy carbon electrode, which blocks the electrochemical reaction. The electrooxidation occurs mainly at the triene moieties of the VD2 molecule. The CD spectroelectrochemical data were treated by the double logarithm method together with nonlinear regression, from which the formal potential E-0 = 1.08 V, alphan = 0.245, the standard electrochemical rate constant k(0) = 4.30( +/- 0.58) x 10(-4) cm s(-1) and the adsorption constant beta = 1.77(+/- 0.25) were obtained. (C) 2001 Elsevier Science B.V. All rights reserved.

一种制备过氧化物酶的新方法

以meso 四 (α ,α ,α ,α Ο 苯乙酰苯 )卟啉为抗原 ,通过动物免疫、细胞融合等技术筛选细胞株 3E4.该细胞株产生的抗体具有结合铁卟啉的能力 ,且表现出过氧化物酶的活力 .该抗体对抗原和铁卟啉的亲和常数为 3.6 5×10 -9和 8.2 0× 10 -8.抗体 铁卟啉复合物催化反应时 ,得到比活力为 46 .875U/mg ,为天然HRP的 18.99% .

毛细管区带电泳柱端安培检测抗癌药物巯嘌吟

报道了一种高效快速检测抗癌药物巯嘌呤的方法——毛细管区带电泳柱端安培检测.考察了巯嘌呤的电化学行为.在最佳操作条件下,获得此药物的检测限为1×10~(-7)mol/L;线性范围为5×10~(-4)～5×10~(-6)mol/L;相关系数为0.995,重现性良好.并用该法检测了人尿样及牛血清蛋白中的巯嘌呤.

聚乙烯醇与4-乙烯基吡啶和丙烯酰胺的共接枝物凝胶用于制备葡萄糖生物传感器

在聚乙烯醇长链骨架上接枝4-乙烯基吡啶和丙烯酰胺合成得三元接枝物，采用这种三元接枝物凝胶固定葡萄糖氧化酶制备了葡萄糖传感器。该酶电极响应时间为7～10s；电流密度在0.65V(vs．Aｇ/AｇCl)；对1mmol/L葡萄糖可达到480nA/mm2，其线性范围为5×10－6～5×10－3mol/L，使用两个月后响应仍在85%左右。

Crystallization behavior of a novel poly(aryl ether ketone): PEDEKmK

Isothermal melt and cold crystallization kinetics of PEDEKmK linked by meta-phenyl and biphenyl were investigated by differential scanning calorimetry in two temperature regions. Avrami analysis is used to describe the primary stages of the melt and cold crystallization, with exponent n = 2 and n = 4, respectively. The activation energies are -118 kJ/mol and 510 kJ/mol for crystallization from the melt and the glassy states, respectively. The equilibrium melting point T-m(0) is estimated to be 309 degrees C by using the Hoffman-Weeks approach, which compares favorably with determination from the Thomson-Gibbs method. The lateral and end surface free energies derived from the Lauritzen-Hoffman spherulitic growth rate equation are sigma = 8.45 erg/cm(2) and sigma(e) = 45.17 erg/cm(2), respectively. The work of chain folding q is determined as 3.06 kcal/mol. These observed crystallization characteristics of PEDEKmK are compared with those of the other members of poly(aryl ether ketone) family. (C) 1997 John Wiley & Sons, Inc.

芳香酯环状低聚物的合成、结构及开环聚合——制备高性能树脂的一条新途径

在“拟高稀释”(pseudo-high-dilution)的模拟条件下,邻苯二甲酰氯和一系列双酚界面缩聚反应选择性地生成了一系列芳香酯环状二聚体.单晶X-射线晶体结构分析其中两个大环二聚体酯表明,这些环状二聚体是没有张力或张力很小的大环结构,选择性地生成环状二聚体是由两种反应单体存在有利于环化的构型决定的.这些没有张力的大环芳香酯低聚物在阴离于催化剂条件下快速地熔融聚合,得到高分子量的线性芳香聚酯.

层状La-Ba-Cu复合氧化物在CO还原NO反应中活性的研究

氮氧化物是严重的空气污染物,催化消除氮氧化物是环保催化研究的热点问题,在已有报道的催化剂体系中复合氧化物和含铜分子筛受到人们的普遍关注,文献中已有报道ABO_3(A=Ln;B=Cr,Mn,Fe,Co,Ni)型复合氧化物作为CO还原NO反应的催化剂.但迄今尚未见有合成LaCuO_3的报道,有关含铜复合氧化物作催化剂的大多是A_2BO_4型的.呈ABO_3结构的含铜复合氧化物只有成层状的超导体如YBa_2Cu_3O_7,本文为了探讨复合氧化物晶体结构对催化活性的影响,首次研究了3种层状ABO_3结构的La-Ba-Cu复合氧化物对CO还原NO反应的活性,发现它们均具有较高的活性,并首次提出了Ba离子在此反应中的作用.1 实验方法催化剂的制备和Cu价态分析见文献[4,5]CO还原NO反应在固定床流动反应体系中进行,反应管为内径6mm石英管,催化剂粒度为40～80目,用量0.2g,空速为7000h~(-1),原料气为NO7.5×10~(-3),CO8.0×10~(-3),He平衡.采用英国产的Pyc Pan气相色谱分析检测N_2O,CO_2,0.5nm分子筛色谱柱检测NO,CO转化率. H_2-TPR在自制装置上...

Dynamic mechanical properties of interpenetrating polymer networks based on polyacrylates and epoxy

Interpenetrating polymer networks (IPNs) based on polyacrylate (poly(polyethylene glycol diacrylate), PEGDA) and epoxy(diglycidyl ether of bisphenol A, DGEBA) were prepared simultaneously Dynamic mechanical properties of the SINs (simultaneous interpenetrating networks) with various compositions were studied. Enhanced mechanical properties were found in this case. From the point of view of pre-swollen networks, all of the PEGDA/DGEBA IPNs were composed of the individual pre-swollen networks. A micro-phase segregation system was produced in the SIN. Glass transition temperatures shifted inward, which was attributed to molecular packing effects or mutual-entanglements of molecular segments among the individual pre-swollen networks. In accordance with the additivity of properties, namely the parallel model, the entanglement density between the two polymer networks reached its maximum at 50/50 PEGDA/DGEBA IPN.

芦丁在玻碳电极上的阳极伏安行为及其测定

本文应用线性扫描伏安法，微分脉冲伏安法和循环伏安法对芦丁在玻碳电极上的阳极伏安行为进行了研究。在0．059mol／LNaH2PO4溶液中于＋0．53V（vs．Ag／AgCl）左右产生一个灵敏的阳极氧化峰，测定下限可达0．01mg／L（1．5×10-8mol／L）。用本法不需分离直接测定了药物制剂，相对标准偏差为2．7％（n＝10），回收率为99％～104％，对电极反应机理进行了探讨。

热致液晶共聚酯/含酚酞侧基聚芳醚砜共混物的流变行为研究

采用溶液共混制备了不同比例的热致液晶共聚酯(LCP)/含酚酞侧基聚芳醚砜(PES—C)共混物。利用锥板流变仪对共混体系的熔体流变性能进行了初步研究,测定了熔体粘度—温度、粘度—剪切速率的关系,结果表明该液晶聚合物能明显降低聚芳醚砜的熔体粘度。