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.

Genetic characterization of asymmetric reciprocal hybridization between the flatfishes Paralichthys olivaceus and Paralichthys dentatus

Interspecific reciprocal crosses between the two flatfishes Paralichthys olivaceus and P. dentatus yielded hybrids with different viabilities. Specifically, the hybrids of P. olivaceus female and P. dentatus male (HI) were found to be viable, while the reciprocal hybrids from P. dentatus female and P. olivaceus male (HII) were completely inviable. All the HII individuals showed morphological deformities and died before first feeding. The chromosome analysis showed that HI individuals had the same chromosome number as parents. However, two chromosomes were missing in HII offspring indicating that the latter were aneuploids. Genomic inheritance from the parents to F-1 progeny was also examined by amplified fragment length polymorphism (AFLP) analyses, and the results showed differences between reciprocal hybrids. Almost all AFLP bands (97.71%) observed in parents were passed on to HI individuals. In contrast, only 86.64% of the AFLP bands from parents were scored in HII individuals. Frequency of lost parental bands was thus significantly higher in HII than that in HI and intraspecific crosses, which was probably associated with chromosomal elimination. In addition, higher segregation distortions were found in hybrids than in controls, although these differences were not significant. The present study indicates that chromosomal elimination and loss of AFLP loci occurred in inviable HII individuals, while such genomic changes were not found in viable HI individuals. Possible implications of such difference on genomic changes for asymmetric viability in reciprocal hybrids are discussed.

A novel C1q-domain-containing protein from Zhikong scallop Chlamys farreri with lipopolysaccharide binding activity

The C1q-domain-containing (C1qDC) proteins are a family of proteins characterized by a globular C1q (gC1q) domain in their C-terminus. They are involved in various processes of vertebrates and supposed to be an important pattern recognition receptor in innate immunity of invertebrates. In this study, a novel member of C1q-domain-containing protein family was identified from Zhikong scallop Chlamys farreri (designated as CfC1qDC) by expressed sequence tag (EST) and rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of CfC1qDC was of 777 bp, consisting of a T-terminal untranslated region (UTR) of 62 bp and a 3' UTR of 178 bp with a polyadenylation signal sequence AATAAA and a poly (A) tail. The CfC1qDC cDNA encoded a polypeptide of 178 amino acids, including a signal peptide and a C1q-domain of 158 amino acids with the theoretical isoelectric point of 5.19 and the predicted molecular weight of 17.2 kDa. The C1q-domain in CfC1qDC exhibited homology with those in sialic acid binding lectin from mollusks and C1qDC proteins from higher vertebrates. The typical 10 beta-strand jelly-roll folding topology structure of C1q-domain and the residues essential for effective packing of the hydrophobic core were well conserved in CfC1qDC. By fluorescent quantitative real-time PCR, mRNA transcripts of CfC1qDC were mainly detected in kidney, mantle, adductor muscle and gill, and also marginally detectable in hemocytes. In the bacterial challenge experiment, after the scallops were challenged by Listonella anguillarum, there was a significant up-regulation in the relative expression level of CfC1qDC and at 6 h post-injection, the mRNA expression reached the maximum level and was 4.55-fold higher than that of control scallops. Similarly, the expression of CfC1qDC mRNA in mixed primary cultures of hemocytes stimulated by lipopolysaccharides (LPS) was up-regulated and reached the maximum level at 6 h post-stimulation, and then dropped back to the original level gradually. In order to investigate its function, the cDNA fragment encoding the mature peptide of CfC1qDC was recombined and expressed in Escherichia coli BL21 (DE3). The recombinant CfC1qDC protein displayed a significantly strong activity to bind LIDS from E. coli, although no obvious antibacterial or agglutinating activity toward Gram-negative bacteria E. coli JM109, L. anguillarum and Gram-positive bacteria Micrococcus luteus was observed. These results suggested that CfC1qDC was absolutely a novel member of the C1qDC protein family and was involved in the recognition of invading microorganisms probably as a pattern recognition molecule in mollusk. (c) 2008 Elsevier Ltd. All rights reserved.