废水中有机磷乐果降解菌的筛选及作用条件

由于乐果等有机磷农药的大量使用引起的土壤及水环境污染问题正威胁着生态安全及人类健康。微生物法降解有机磷农药因其经济有效性近年来成为研究的热点。实验采用室内培养方法,从吉化农药厂废水污泥中分离筛选出一株能在高浓度农药乐果中生长的细菌菌株。结果表明,该菌株最适生长pH值为7．0左右,具有相对稳定的pH值生长范围（pH6．0～8．0）,最适生长温度为30℃,3天后生长进入稳定期;得到的菌株对高浓度的乐果具有一定耐受性,在pH7．0、30℃温度条件下,1天内就可对乐果具有好的降解效果。     

Ozone-Based Advanced Oxidation Processes for the Decomposition of N-Methyl-2-Pyrolidone in Aqueous Medium

The present study investigates the decomposition of N-Methyl-2-Pyrolidone (NMP) using conventional ozonation (O₃), ozonation in the presence of UV light (UV/O₃), hydrogen peroxide (O₃/H₂O₂), and UV/H₂O₂ processes under various experimental conditions. The influence of solution pH, ozone gas flow dosage, and H₂O₂ dosage on the degradation of NMP was studied. All ozone-based advanced oxidation processes (AOPs) were efficient in alkaline medium, whereas the UV/H₂O₂ process was efficient in acidic medium. Increasing ozone gas flow dosage would accelerate the degradation of NMP up to certain level beyond which no positive effect was observed in ozonation as well as UV light enhanced ozonation processes. Hydrogen peroxide dosage strongly influenced the degradation of NMP and a hydrogen peroxide dosage of 0.75 g/L and 0.5 g/L was found to be the optimum dosage in UV/H₂O₂ and O₃/H₂O₂ processes, respectively. The UV/O₃ process was most efficient in TOC removal. Overall it can be concluded that ozonation and ozone-based AOPs are promising processes for an efficient removal of NMP in wastewater.     

Characterization of catalysts and membrane in DMFC lifetime testing

The lifetime and performance of a direct methanol fuel cell (DMFC) were investigated to understand the correlation between the structure of catalysts/membrane and cell performance versus time. The cell polarization and performance curves were obtained during the DMFC operation with the time. The catalysts and Nafion^® membrane of the membrane electrode assembly (MEA) from the lifetime test were comprehensively examined by XRD, HRTEM, FTIR and Raman spectroscopy techniques. The results revealed that there was significant performance degradation during the first 200 h operation; while the degradation was slowing down between 200 and 704 h operation. The degradation became worse after 1002 h operation. The increases of the catalyst particle size from both anode and cathode catalysts were observed after the DMFC lifetime test. The changes of microstructure, surface composition, the interfacial structure of the MEA, and the aging of Nafion^® under the DMFC lifetime tests were also observed.     

聚丙烯管材专用料的熔体降解及其对力学性能的影响

在双螺杆挤出机中，对无规共聚聚丙烯(PP-R)和嵌段共聚聚丙烯(PP-B)管道专用料的熔体降解行为及其对力学性能的影响进行了研究；对助剂量、熔体温度等工艺条件对降解行为的影响进行了讨论。结果表明：降低熔体温度，可明显降低PP-R和PP-B的热降解速率；降解优先发生在长链分子，导致摩尔质量减小，摩尔质量分布变窄，力学性能下降。     

Mycoremediation of chlorpyrifos and lambda-cyhalothrin by two species of filamentous fungi

Chlorpyrifos and lambda-cyhalothrin are two of the most commonly used insecticides in agriculture. Their residues reach water courses, affecting aquatic fauna and subsequently human beings. Aspergillus viridinutans and Penicillium implicatum isolated from water drains at El-Giza and El-Ismailia governorates were grown in potato dextrose broth media supplemented with different concentrations of chlorpyrifos and lambda-cyhalothrin. Samples, taken at 0, 7 and 14 days, were analysed for pesticide residues by gas chromatography. The fungal species showed biodegradation potentials of 2.5, 5 and 20 ppm of chlorpyrifos and lambda-cyhalothrin. Degradation percentage reached 100% after 14 days of incubation of both pesticides (2.5 ppm) individually with the two tested fungal species. The values of degradation rate, besides the weights of dry fungal biomasses ensured that the optimum chlorpyrifosconcentration for A. viridinutans and P. implicatum was 5 ppm, while the optimum lambda-cyhalothrin concentration for A. viridinutanswas 5 ppm and 2.5 ppm for P. implicatum.     

金属化膜电容器交流和直流电压劣化特性分析

金属化膜电容器是模块化多电平换流器（MMC）的关键设备,在长期工作电热应力作用下其状态不断劣化,给换流器和柔性直流输电系统的安全运行带来隐患。本文分别搭建了交、直流加速劣化试验平台,得到了不同电压作用形式和不同状态劣化程度的样品。进而利用共聚焦显微镜和扫描电子显微镜对解剖样品进行表面观测,结合能谱扫描的元素分析结果,掌握了金属化膜电容器在不同电压形式下的状态劣化特性。结果表明,电容器由于在不同电压下的劣化机理不同,电容值下降规律和劣化点形貌有明显不同;通过加速老化试验,得到了电容器在交、直流电压下劣化点的典型形貌特征,从而可以进一步分析金属化膜电容器劣化机理,具有实用价值。 关键词：金属化膜电容器; 劣化机理; 自愈; 电化学腐蚀 中图分类号：TM536     

模拟胃环境中丝素蛋白复合材料的溶蚀机制

以聚乙二醇为增塑剂,通过水相共混法制备了不同比例的丝素蛋白/聚乙烯醇/聚乙二醇复合材料。利用红外光谱对复合材料进行了结构表征,并通过失重试验、红外光谱(FTIR)、X-射线衍射(XRD)、扫描电镜(SEM)对复合材料在模拟胃环境中的溶蚀机制进行了研究。结果表明,丝素蛋白/聚乙烯醇/聚乙二醇复合材料的溶蚀降解首先从丝素蛋白的溶出、分解,并形成细微孔道开始,然后胃液通过细微孔道逐步深入并溶蚀聚乙二醇和聚乙烯醇。该丝素蛋白/聚乙烯醇/聚乙二醇复合材料具有潜在的药物缓释应用前景。     

Design of an IV Formulation of an Unstable Prodrug Candidate for Prostate Cancer Treatment: Solution Chemistry of N-(glutaryl-hyp-ala-ser-cyclohexylglycyl-gln-ser-leu)-doxorubicin

ABSTRACT

The chemical degradation of N-(glutaryl-hyp-ala-ser-cyclohexylglycyl-gln-ser-leu)-doxorubicin (henceforth referred to as doxorubicin peptide conjugate 1) was studied in buffered aqueous solution. The pH-rate profile of degradation shows that the doxorubicin conjugate is most stable between pH 5 and 6. The dependence of log k_obsd on pH in acidic medium is characteristic of specific acid-catalysis of the sugar hemiaminal of 1 (as in the case of doxorubicin). Isolation of degradates and structural determination shows that the degradation at lower pH values yields the water-insoluble aglycone doxorubicinone, supporting the mechanism of acid-catalyzed loss of the amino sugar. At pH higher than 5, a more complicated degradation pattern is observed, including the loss of the amino sugar and the aromatization of the saturated ring to give 7,8-dehydro-9,10-desacetyldoxorubicinone as one of the major products. Around the pH of maximum stability in solution, the rate of degradation of 1 is significantly greater than that for doxorubicin, which rules out the formulation of a room temperature solution product with a sufficiently long shelflife for market use. Design of a stable lyophilized formulation for sterile reconstitution based on the physicochemical properties of 1 is described.     

Degradation Kinetics of Fluorouracil-Acetic-Acid-Dextran Conjugate in Aqueous Solution

ABSTRACT

The degradation kinetics of fluorouracil-acetic-acid-dextran conjugate (FUAC-dextran) was investigated in various buffer solutions with different pH value and physiological saline solution at 60°C and 37°C, respectively. The hydrolytic reaction displayed pseudo-first-order degradation kinetics. Hydrolytic rate constant obtained was the function of pH value and independent of species of buffering agents. The smallest rate constant was observed at pH round 3.00. The activation energy of the hydrolytic reaction was estimated from Arrhenius equation as 88.73 ± 6.00 kJ·mol^?1. The special base catalytic degradation of the conjugate was observed from acidic to slight alkaline condition and the special base catalytic rate constants were calculated. The conjugate was more stable in physiological saline than that in buffer solution at pH 7.00 or 9.00 at 37°C. The results revealed that the conjugate was stable in acidic condition and will degrade in alkaline condition.     

Degradation of curdlan using hydrogen peroxide

Curdlan, a linear glucan interconnected by β-(1 → 3) linkages, is soluble in alkaline solutions but not in water, which limits its wide application, particularly in the food industry. In this study, curdlan was subjected to oxidative degradation using hydrogen peroxide (H₂O₂). The optimal hydrolysis conditions were determined, and the results were as follows: reaction time, 40 min; temperature, 60 °C; H₂O₂ concentration, 1.5% (v/v); and NaOH concentration, 2.5 M. Under these optimised conditions, the maximum dextrose equivalent value (13.49%) was obtained. The composition and the structure of the hydrolysates were characterised by high-performance liquid chromatography and Fourier-transform infra-red spectroscopy, respectively. The hydrolysates were filtered, neutralised with HCl, concentrated to ∼12% (w/v), desalted, and freeze dried to yield a water-soluble, white powder. The (1 → 3)-β-d-glucan oligosaccharide content of the product was 98.6% and the yield was 91.4% (w/w).