微生物降解有机磷农药残留的研究进展

从微生物降解有机磷农药的种类、降解机理、降解基因等方面综述了微生物降解有机磷农药近年来的研究进展,探讨了微生物降解有机磷农药研究领域的发展趋势及进一步的研究方向,并提出建议。     

微生物降解土壤残留农药的研究进展

综述了在环境中降解土壤农药的微生物、微生物降解农药的机理、在自然条件下影响微生物降解农药的因素以及农药微生物降解研究方面的新技术和新方法。在农药的微生物降解研究中,应重视自然状态下微生物对农药的降解过程,分离构建由天然的微生物构成的复合系,利用微生物复合系进行堆肥或把堆肥应用于被污染的环境。     

高效氯氟氰菊酯的微生物降解研究进展

简介了高效氯氟氰菊酯的性质特征,综述了其在土壤和农作物中的残留现状以及降解该农药的微生物、降解酶、降解基因、降解机理和途径等,提出了寻求超强降解的微生物资源、提高微生物酶的稳定性和降解效率将是今后微生物降解高效氯氟氰菊酯的重点研究方向。     

零价铁处理有机氯农药的实验研究

本文结合氯代烃和多氯联苯等氯代芳香烃的零价铁还原脱氯技术的研究进展,对零价铁在还原降解六六六、滴滴涕和六氯苯等有机氯农药中的应用进行了评述,讨论了零价铁降解有机氯农药的反应机理、动力学、铁表面活性作用,指出了该研究技术中存在的某些问题及不足并提出了建议,为之后进一步开展有机氯农药的零价铁脱氯降解实验研究确定了方向.     

环境中有机磷农药降解方法的研究进展

有机磷农药广泛使用于农业生产中,但是对环境造成了严重的污染。综述了有机磷农药的氧化降解、微生物降解、光催化降解方法,介绍了降解中的影响因素和未来发展的研究方向。     

农药残留实现微生物降解

日前，由福建安溪县农业与茶果局和南京农业大学合作的茶园土壤和茶树农药残留微生物降解菌剂试验取得成功，效果明显。农药残留微生物降解菌剂是由南京农业大学历经16年研究创造出来的新型生物修复新技术，主要通过应用微生物含有的一些酶类来降解土壤与农作物中的农药残留。对土壤中滴滴涕和植株上的澳氰菊酯等农药残留起到高效的降解作用，有效改善土壤品质。     

毒死蜱微生物降解研究进展

毒死蜱目前在我国是农药中的畅销品种,用量相当大,但大量使用也带来了环境污染问题,利用微生物降解毒死蜱残留是一种非常有效的方法.对毒死蜱的应用、残留毒理,目前已筛选、分离出的微生物降解菌种类的研究情况进行了综述,并对今后微生物降解农药的应用前景和发展趋势进行了展望.     

不同氧化剂对土壤中有机氯农药γ-HCH降解效果的影响

有机氯农药γ-HCH杀虫活性强、化学性质稳定,在环境中不易降解,残留期长,对生态环境和人体危害严重.通过加速溶剂萃取法联合气相色谱法,研究了Fenton试剂、热活化的Na2 S2 O8对土壤中有机氯农药γ-HCH的降解效果.结果表明,Fenton试剂和Na2S2O8在氧化降解γ-HCH方面都表现出很高的活性.当水土质量...     

微生物降解七氯的研究进展

七氯(Heptachlor)是一种很难降解的持久性有机污染物。微生物降解七氯在处理七氯残留问题时是一种很有效的方法。了解七氯的微生物降解发展历程,对于同类有机氯农药的降解有很大的启示作用。本文就微生物降解七氯的研究进展进行了综合评述,介绍了七氯微生物降解机制、降解菌种,重点归纳了七氯的好氧生物降解、厌氧生物降解以及其它降解方法,分析了农药本身和微生物本身特性及环境作用等因素对七氯生物降解的影响,指出了研究中存在的问题,并认为降解菌在分子水平上的机理研究以及微生物联合其它高级氧化技术等新型水处理技术来提高降解效率具有很好的发展前景。     

农药细菌降解研究进展

农药作为广泛使用并与人类生存和发展密切相关的化学物质 ,其在环境中的残留、迁移和降解主要取决于生物和非生物因子二个方面 ,其中因微生物的作用而引起的降解过程称为生物降解 (biodegrada tion) ,即农药通过微生物及其代谢酶系的作用分解成为小分子。近几十年的研究成果充分肯定了农药的生物降解在环境中占有重要地位。不同农药的降解速率变化很大 ,有的农药如滴滴涕和狄氏剂等难以降解而长期存在于环境中 ,并在食物链中发生累积[1 2 ] ;一些农药如有机磷等要比持久性有机氯类农药易于降解 ,莠去津和西玛津等降解缓慢并从地表渗透到地下…     

Simulated evaluation of the degradation of hydrophobically associative polymers in the formation

In this work, indoor physical simulation experiments were used to examine the effects of shear, thermal, chemical, and microbial degradation on the properties of the hydrophobic associative polymer AP-P4. It was discovered that the viscosity of the polymer solution generally decreased as the shear time was extended. The larger the shear strength, the lower the solution viscosity. Fitting of the nonlinear equation of solution viscosity with shear time, η = 12,988 t^−1.08. When thermal degradation started, the solution viscosity first started to rise, however, this phase was just a short one. The viscosity of the solution gradually started to decrease as the thermal degradation period grew. In addition, the trends of properties like hydrokinetic radius, hydrophobic connectivity, and hydrolysis essentially followed the same patterns as those of solution viscosity. At the beginning of the degradation process, the viscosity retention of the polymer solution without oxygen is significantly higher than that of the aerobic environment. However, the difference between the two becomes smaller as the degradation time increases. In addition, the AP-P4 had good temperature resistance and aging resistance capabilities when iron ions were present. Finally, it was discovered that AP-P4 had a strong antibacterial effect, which decreased the viscosity brought on by microbial action.     

Thermal Degradation of Polystyrene

The thermal degradation of polystyrene in the absence of oxygen is examined, at temperatures above or below 300°C. The decrease in degree of polymerisation occurring either with negligible volatilisation at lower temperatures, or with evolution of low molecular weight products at higher temperatures, is simulated by Monte-Carlo procedures. The results suggest that below 300°C, scission of the polymer chains is random, and involves also a minor fraction of some abnormal, as yet unidentified, structures. Above 300°C, an extensive intermolecular transfer process seems to be the main cause of the decrease in degree of polymerisation, whereas an overall depolymerisation of 100 structural units at each chain scission is the source of volatilisation.     

Polymer pyrolysis: A resolution of anomalies in kinetic schemes for the rate of evolution of volatile products

Kinetic schemes proposed by three groups of workers for polymer pyrolysis have been critically examined, in order to resolve apparent anomalies, especially in the way in which the overall first-order rate constant for volatile evolution by depropagation mechanisms, involving different modes of initiation and termination, have been interpreted. In one scheme, the treatment of rate was found to be inappropriate for changing-volume systems, and the resulting rate expressions therefore cannot be recommended. When choice of units, conventions, and symbols was taken into account, the other schemes were found to be totally compatible. These schemes lead to identical expressions for the initial rate of evolution of a volatile product, provided the symbols are defined specifically according to the conventions chosen. These expressions are to be recommended for studies of this kind.     

甲氰菊酯的酶促降解

阴沟肠杆菌w10j15中提取到甲氰菊酯降解酶,测定了其对甲氰菊酯的降解特性。研究结果表明,降解酶在40℃、pH7 5时对甲氰菊酯显示最大的降解活性,对甲氰菊酯的降解率为65%。经实验测定,其每毫克酶蛋白质最大降解速率Vmax为48 08 nmol·mL-1·min-1,米氏常数(Km)为332 23 nmol·mL-1。     

气氛对低氮天然橡胶热降解的影响

采用热重分析(TG),研究了恒定升温速率下,低蛋白橡胶在氮气和空气气氛中的热降解行为,考察了反应气氛对降解速率、降解率和动力学参数的影响,分析了两者降解机理的可能差别。发现降解温度和降解率,氮气中均高于空气中;表观反应级数氮气中为2.0级,空气中为1.9级。     

线性PBS基脂肪族聚酯的合成和降解研究

为了探讨线性PBS基脂肪族共聚酯的结构和降解之间的关系,首先合成了线性PBS基脂肪族共聚酯,即聚丁二酸丁二醇酯-共-聚己二酸丁二醇酯P(BS-co-BA),聚丁二酸丁二醇酯-共-癸二酸丁二醇酯P(BS-co-BSe),并将线性PBS基脂肪族共聚酯及PBS在土壤悬浮液中进行降解,通过GPC、熔点测定仪对线性PBS基脂肪族共聚酯的分子量和熔点进行了测定;通过测定降解过程中失重率和降解前后聚酯薄膜表面形貌来对共聚酯降解程度进行表征。结果表明:随着二元酸碳链的增长,分子对称性降低,降解性能增大。通过观察分子量,熔点及降解失重率的测定结果,得出分子量越大,降解越不容易进行;熔点越小,降解性能越好。     

Moisture and temperature degradation of double cantilever beam adhesive joints

In this work, the double cantilever beam (DCB) test is analysed in order to evaluate the combined effect of temperature and moisture on the mode I fracture toughness of adhesives used in the automotive industry. Very few studies focus on the combined effect of temperature and moisture on the mechanical behaviour of adhesive joints. To the authors’ knowledge, the simultaneous effect of these conditions on the fracture toughness of adhesive joints has never been determined. Specimens using two different adhesives for the automotive industry were subjected to two different ageing environments (immersion in distilled water and under 75% of relative humidity). Once they were fully degraded, they were tested at three different temperatures (?40, 23 and 80 °C), which covers the range of temperature an adhesive for the automotive industry is required to withstand. The aim is to improve the long term mechanical behaviour prediction of adhesive joints. The DCB substrates were made of a high strength aluminium alloy to avoid plastic deformation during test. The substrates received a phosphoric acid anodisation to improve their long term adhesion to the adhesive. Results show that even though a phosphoric acid anodization was applied to the adherends, when the aged specimens were tested at room temperature and at 80 °C, they suffered interfacial rupture. At ?40 °C, however, cohesive rupture was observed and the fracture toughness of the aged specimens was higher.     

用热分析方法研究络合物Pd（NH3）4Cl2.H2O的热氧降解过程与动力学

用差热分析法、热重分析法和微分热重分析法研究经各合物Ｐｄ（ＮＨ３）４Ｃｌ２．Ｈ２Ｏ在空气流中的热氧解过程和动力学，发现Ｐｄ（ＮＨ３）４Ｃｌ２Ｈ２Ｏ热氧降解过程由４个紧连步骤组成。     

Degradation of low density polyethylene during extrusion. III. Volatile compounds in extruded films creating off‐flavor

This study was aimed at finding a correlation between the experienced off‐flavor in packaged foods and the presence of specific degradation products in PE packaging films. The possibility to trap degradation products by chemical reactions with scavengers, that is, zeolites and maleic anhydride grafted LLDPE, were investigated. This trapping would prevent the degradation products from migrating to the polymer film surface and further into food in contact with the film. This work concludes that off‐flavor in water packed in LDPE‐films depends on extrusion temperature and the content of oxidation products in the polymer film. At lower extrusion temperatures, reactive additives to the LDPE material could control the release of off‐flavor giving components. Adsorbents, such as zeolites, which are able to adsorb degradation products, are effective also at higher extrusion temperatures. The amount of oxidized degradation products in the films correlated well to the perceived off‐flavor in the packed water. The presence of aldehydes and ketones have a clear impact on the off‐flavor. The best correlation between off‐flavor and oxidized components were found for C₇? C₉ ketones, and aldehydes in the range of C₅ to C₈. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 847–858, 2005     

芳纶的热光老化降解研究

阐述了芳纶的热、光老化降解研究的进展情况。指出芳纶在实际使用时,不可避免地会受到环境中热、光等因素的作用,发生老化降解,从而影响其性能的发挥。应加强这方面的研究工作,尤其是耐光性,探讨相应防护改进措施,使得芳纶的使用寿命更长,使用范围更广。