K+ sensors based on supported alkanethiol/phospholipid bilayers

A novel kind of K+ sensor with valinomycin-incorporated bilayers supported on a gold electrode consisting of self-assembled alkanethiol monolayers (SAMs) and a lipid monolayer has been fabricated successfully. The lipid monolayer is deposited on the alkylated surface of the first alkanethiol monolayer through three different methods, such as the Langmuir-Blodgett (LB) technique, painted method and painted-frozen method. The response of K + sensors produced by a painted or painted-frozen lipid monolayer on an alkanethiol alkylated gold electrode is larger than that by the LB method, which is due to the difference in fluidity of the three kinds of bilayers. Selectivity coefficients KK+, Na+, KK+, Li+, KK+, Ca2+ and KK+, Mg2+ are 10(-4), 10(-4), 2 x 10(-5) and 3 x 10(-5) respectively, and there is no obvious difference among different fabricating methods. A linear response toward the potassium ion was found in the range from 10(-1) M to 10(-5) M with the detection limit of 10(-6) M. The sensor has a slope of 60 mV per decade. Meanwhile, the longevity of the sensor was improved obviously for at least two months at about -10 degrees C. The higher stability shows the possibility to fabricate a practical biosensor.

含二羟基二苯酮系列热致液晶共聚酯的合成与表征──Ⅱ．含4，4＇－二羟基二苯酮，对苯二甲酸，对羟基苯甲酸，间苯二酚的共聚酯

采用直接熔融缩聚及固相聚合方法由４，４’－二羟基二苯酮（ＢＨＰ），对苯二甲酸（ＴＰ），对羟基苯甲酸（ＰＨＢＡ），间苯二酚（ＲＥＳ）成功地合成了四元共聚酯高分子，该聚酯的组成结构及性质由偏光显微镜、广角Ｘ－射线衍射、ＤＳＣ等手段进行表征，结果表明共聚酯具有向列型液晶特征．

Synthesis and properties of block copolymers of poly(ether sulphone)s with liquid crystalline polyester units

Block copolymers of poly(ethersulphone) (PES) oligomers with liquid crystalline polyester units were synthesized by the reaction of dihydroxy-terminated poly(ether sulphone) oligomers (number-average molecular weights: 704, 1,158 and 2570) and terephthaloyl bis(4-oxybenzoyl chloride), and their properties were investigated. The results indicated that the copolymer with PES segments of molecular weight of 704 possessed birefringent features when annealed at 360 degrees C, while the copolymer with PES segments of molecular weight of 2,570 became isotropic. Also, the block copolymers had a better chemical resistance and high-temperature stability than PES.

The direct electrochemistry of cryo-hydrogel immobilized myoglobin at a glassy carbon electrode

A cryo-hydrogel membrane (CHM) immobilized at a glassy carbon (GC) electrode is reported for the direct electron transfer of redox proteins. The most attractive characteristics of this CHM were its hydrophilic micro-environment for incorporated proteins to retain their activities, its high ability for protection against interference of denatured and adsorbed proteins at the electrode, its potential applications for various proteins or enzymes, as well as its high mechanical strength and thermal stability. A clear well developed and stable redox wave was obtained for commercially available horse heart myoglobin without further purification, giving a peak to peak separation Delta E(p) = 93 mV at 5 mV s(-1) and the formal electrode potential E(0)' = -0.158 V (vs. Ag/AgCl). The formal heterogeneous electron transfer rate constant was calculated as k(0)' = 5.7 X 10(-4) cm s(-1) at pH 6.5, showing rapid electron transfer was achieved. The pH controlled conformational equilibria, acid state --> natural state --> basic I state --> basic II state, of myoglobin at the CHM GC electrode in the pH range 0-13.8 were also observed and are discussed in detail.

不同共混比Ln-BR/NR的性能

研究了稀土顺丁橡胶(Ln—BR)与天然橡胶(NR)以不同比例共混后生胶、混炼胶和硫化胶的性能,并与相同条件下的镍系顺丁橡胶(Ni-BR)/NR共混胶的性能进行了对比.结果表明,共混胶随Ln—BR用量的增大,ML_(1+4)~(100℃)降低,工艺行为良好,硫化胶力学性能、磨耗、湿滑指数和生热值下降,并且Ln—BR/NR硫化胶的抗湿滑性和动态疲劳性均优于Ni-BR/NR硫化胶.

控制电位电解二氧化氮监测仪的研制

概述二氧化氮(NO_2)是一种棕色有毒气体,具有强烈的刺激性、腐蚀性和可吸附性。我国工业卫生标准规定NO_2浓度不允许超过5mg/m_3,即相当于2.5ppm。大气中氮氧化物浓度为0.02至0.15PPm。测定NO_2的方法主要有比色法、检测管法、库仑法和化学发光法等。1974年美国Blurton等人首先提出控制电位电解气体成份监测仪。此后,美、日等国家相继研制并生产了CO、NO_2、NO、SO_2、H_2S等系列气体监测仪。作者所研制的二氧化氮监测仪亦依据了上述基本原理。在此基础上改变实验条件后尚可用以测量一氧化碳、硫化氢、

胰岛素依赖型糖尿病患儿全血自由基及抗自由基的检测

本文测定了25例胰岛素依赖型糖尿病(IDDM)患儿及25例健康对照组的全血自由基(FR)、血清过氧化脂质(LPO)、超氧化物岐化酶(SOD)、维生素 E(V_E)和硒(Se)。结果表明 IDDM 患儿全血 FR 与 LPO、V_E、Se 均明显高于健康对照组,SOD 活性低于对照组(P<0.01)。相关关系分析结果IDDM 患儿全血 FR 与 LPO、SOD 相关性不明显,指出应用电子自旋共振(ESR)技术检测全血 FR,同时测定 LPO 和 SOD,能更准确、更敏感反映患儿体内自由基水平。以上3项指标检测结果证明自由基参与了 IDDM 的发生发展过程。本文并对 V_E 与 Se 的检测结果与 IDDM 的关系进行了分析。

等离子体聚合法制备膜蒸馏用疏水微孔复合膜

本文以八氟环丁烷为单体,采用等离子体聚合法将亲水性硝酸纤维素微孔膜改性,制得疏水硝酸纤维素微孔复合膜。所得疏水微孔复合膜可用于膜蒸馏,并具有优良的膜蒸馏性能,其通量达到反渗透水平。利用扫描电镜、X-射线显微分析和XPS等分析手段研究了聚合条件对所得复合膜结构性能的影响.

ANODIC-OXIDATION OF HYDRAZINE ON GLASSY-CARBON MODIFIED BY MACROCYCLIC TRANSITION-METAL COMPLEXES .1. COBALT PROTOPORPHYRIN DIMETHYL ESTER MODIFIED ELECTRODE

The electrocatalytic oxidation of hydrazine (N2H4) on a glassy carbon electrode (GC) modified by monolayer and polymer films of cobalt protoporphyrin dimethyl ester (CoPP) has been studied. Both the monolayer and polymer films of CoPP are very active to the anodic oxidation of N2H4. The activity of CoPP for the anodic oxidation of N2H4 is dependent on the pH of the solution, and the thickness of polymerized CoPP film. The oxidation kinetics were examined by methods of cyclic voltammetry, rotating disc electrodes and steady-state polarization measurement.

稀土元素对LD31挤压型材的组织和性能的影响

采用金相法和扫描电镜研究了稀土元素在LD31RCS铝型材合金中的分布、存在状态及其对合金金相组织和性能的影响。结果表明,适量稀土主要富集在晶界上,它使合金组织细化,强度、硬度及挤压速度明显提高。过量稀土会形成Al-Si-Fe-RF多元球团状质点,促进韧窝的形核和发展,但它使合金组织粗化,强度和硬度下降。对掺法生产RE-LD31合金的稀土含量以0.2wt％为宜。

PVF_2/PEA共混体系辐射效应研究

本文通过DSC测定,研究了PVF_2/PEA共混体系的辐射效应,首次发现辐照后共混体系产生熔融峰分裂现象,建立了共混体系的β_b值计算式,并将线性聚合物的溶胶分数与辐照剂量间的关系式(1)推广应用到PVF_2/PEA共混体系。

Sequence analysis of the ITS region and 5.8S rDNA of Porphyra haitanensis

The sequences of the ITS (internal transcribed spacer) and 5.8S rDNA of three cultivated strains of Porphyra haitanensis thalli (NB, PT and ST) were amplified, sequenced and analyzed. In addition, the phylogenic relationships of the sequences identified in this study with those of other Porphyra retrieved from GenBank were evaluated. The results are as follows: the sequences of the ITS and 5.8S rDNA were essentially identical among the three strains. The sequences of ITS l were 331 by to 334 bp, while those of the 5.8S rDNA were 158 by and the sequences of ITS2 ranged from 673 by to 681 bp. The sequences of the ITS had a high level of homology (up to 99.5%) with that of P. haitanensis (DQ662228) retrieved from GenBank, but were only approximately 50% homologous with those of other species of Porphyra. The results obtained when a phylogenetic tree was constructed coincided with the results of the homology analysis. These results suggest that the three cultivated strains of P. haitanensis evolved conservatively and that the ITS showed evolutionary consistency. However, the sequences of the ITS and 5.8S rDNA of different Porphyra species showed great variations. Therefore, the relationship of Porphyra interspecies phyletic evolution could be judged, which provides the proof for Porphyra identification study. However, proper classifications of the subspecies and the populations of Porphyra should be determined through the use of other molecular techniques to determine the genetic variability and rational phylogenetic relationships.