Anaerobic degradation of microcrystalline cellulose: kinetics and micro-scale structure evolution

The degradation kinetics and micro-scale structure change of microcrystalline cellulose during anaerobic biodegradation were investigated. A modified Logistic model was established to properly describe the kinetics, which showed good fitness and wide applicability for cellulose degradation. A maximum degradation rate of 0.14 g L⁻¹ h⁻¹ was achieved after cultivating for 51.5 h. This result was in good agreement with the scanning electron microscope and X-ray diffraction analysis. Channels of 400-500 nm size started to occur on the crystalline surface of cellulose at around the inflexion time. Accordingly, the crystallinity significantly decreased at this point, indicating a degradation of the crystalline structure zones by anaerobic bacteria. This study offers direct morphological evidence and quantitative analysis of the biodegradation process of cellulose, and is beneficial to a better understanding of the cellulose degradation mechanism.     

Enhancement of heavy metal accumulation by tissue specific co-expression of iaaM and ACC deaminase genes in plants

The aerobic riboflavin (Rf)-sensitized photodegradation of the endocrine disruptor 4,4'-isopropylidenebisphenol (bisphenol A, BPA), and of the related compounds 4,4'-isopropylidenebis(2,6-dibromophenol) and 4,4'-isopropylidenebis(2,6-dimethylphenol) has been studied in water and water-methanol mixtures through visible-light continuous photolysis, polarographic detection of oxygen uptake, stationary and time-resolved fluorescence spectroscopy, time-resolved near-IR phosphorescence detection and laser flash photolysis techniques. Bisphenols (BPs) quench excited singlet and triplet states of Rf, with rate constants close to the diffusion limit. BPs and dissolved molecular oxygen, employed in similar concentrations, competitively quench triplet excited Rf. As a consequence, superoxide radical anion and singlet molecular oxygen (O(2)((1)Delta(g))) are produced by electron- and energy-transfer processes, respectively, as demonstrated by auxiliary experiments employing selective quenchers of both oxidative species and the exclusive O(2)((1)Delta(g)) generator Rose Bengal. As a global result, the photodegradation of Rf is retarded, whereas BPs are degraded, mainly by an O(2)((1)Delta(g))-mediated mechanism, which constitutes a relatively efficient process in the case of BPA. Oxidation, dimerization and fragmentation products have been identified in the photooxidation of BPA. Results indicate that BPs in natural waters can undergo spontaneous photodegradation under environmental conditions in the presence of adequate photosensitizers.     

冷却-高压静电一体化技术在高温定型机油烟废气净化中的应用

采用冷却-高压静电一体化技术处理印染企业的高温定型机油烟废气,将蒸发冷却、间接水冷、高压静电法集成一体.弥补了传统水喷淋技术与湿法静电技术存在二次污染的不足.通过优化参数,提高了污染物去除率和废油,余热的回收率,白坯布高温定型机每天每台可回收废油188 kg.     

The study on the dechlorination of OCDD with Pd/C catalyst in ethanol-water solution under mild conditions

Dechlorination of octachlorodibenzo-p-dioxin (OCDD) was carried out in ethanol-water (v/v=1:1) solution of NaOH in the presence of Pd/C catalysts with the use of H(2). The substrate was dechlorinated with Pd/C under mild conditions (atmospheric pressure and <100 degrees C) to give a chlorine-free product, dibenzo-p-dioxin (DD), in high yields. After reaction of 3h at 50 degrees C, 95.9% OCDD was degraded to low dechlorinated congeners and the yield of DD was 77.4%. We have also studied the dechlorination selectivity of chlorine atoms on the different substituted positions and postulated the dechlorination pathway of OCDD. For OCDD, the 2-position has higher reactivity than 1-position, but the difference is very small. From the distribution statistics of the intermediates during the reaction, we postulate that the steric effect plays an important role during the reaction and affect the dechlorination pathway of OCDD.     

基于Web的热带气旋灾害信息管理系统的设计与应用

用基于Web的页面显示、业务逻辑、数据访问的B/S三层结构,在Microsoft SQL Server2000和Microsoft Visual Studio2005环境下设计开发了热带气旋灾害数据库信息管理系统。对不同类型的数据,采用多对多的数据映射关系,并以不同的方式进行不同的数据管理。为了将没有统一数据格式的热带气旋灾害信息源数据,能够正确地导入到SQL Server数据库中,编写了专门的C++程序对数据格式化,实现数据格式的BNF定义,同时,在系统的设计中,融入灾害评价方法模型供用户选择使用,并采取多项行之有效的措施以防止SQL注入式攻击。     

Impact of population growth and land-use change on water resources and ecosystems of the arid Tarim River Basin in Western China

Time series data on population change, economic development, climate change, water volume and quality and oasis land-use change were collected to study the interactions between these factors in the arid Tarim River Basin, China. The study reveals that precipitation and stream flow in headwater streams increased, but stream flow in the main Tarim River had reduced significantly over the past three decades. This implies that human activity, rather than climate change, dominated the recent environmental changes in the river basin. As a result of population growth and cultivated land expansion in the upper and middle reaches of the river, severe problems of water shortage, water pollution, death of natural vegetation, soil salinization, desertification and sand-dust storms have occurred, particularly in downstream areas of the river basin. These problems have had serious negative effects on the health of local people and sustainable social economic development in the region. Some development strategies are proposed to deal with these problems.     

类二噁英多氯联苯生殖毒性的研究进展

类二噁英多氯联苯(DlPCBs)作为典型的环境内分泌干扰物,会干扰接触个体或其后代的内分泌功能,破坏机体的神经系统、免疫系统,尤其对生殖系统的影响最为明显,比如对生殖器官的形态与功能、生殖内分泌、原始生殖细胞及其受精和早期胚胎发育等产生严重影响,最终导致各种生殖系统疾病的发生。DlPCBs的蓄积性及半挥发性使其在环境中分布广泛,半衰期长的特点使其将对动物及人类的生存和健康造成难以想象的影响。本文综述了DlPCBs的分类与构成、一般性质、生殖毒性以及其可能的致病机理,并对DlPCBs生殖毒性机理研究的重点方向进行了展望。     

复合表面活性剂对污染土壤中柴油的增溶和洗脱作用

研究了3种表面活性剂及其不同浓度配比对五种柴油链烃的增溶及对柴油污染土壤的洗脱作用.结果表明,复合表面活性剂的增溶效果优于单一表面活性剂,其中尤以阴离子表面活性剂SDS与非离子表面活性剂Tw-80的配比效果最佳;随阴离子表面活性剂复合比例的提高,可以有效地降低复合表面活性剂混合胶束的临界胶束浓度,提高单位表面活性剂接纳目标污染物的能力,增大目标链烃分配进入胶束相的倾向,同时有效降低增溶平衡时对表面活性剂用量的要求;高浓度的阴离子表面活性剂具有很高的污染洗脱效率,非离子表面活性剂Tw-80则易被土壤吸附而导致洗脱效率低下,但阴离子表面活性剂SDS与Tw-80配比能够有效地改善Tw-80易被土壤吸附的现象,并随复合比例提高而不同程度的增强污染土壤中柴油的洗脱效果.     

东大别地区重大地震事件深部地壳结构特征

本文应用东大别地区层析成像研究结果,对研究区重大地震事件的深部地壳结构特征进行了研究,结果表明：霍山地区的2次MS≥6.0级地震在深部地壳结构上具有一定的相似性;1970年以来的12次MS≥4.0地震在25 km深度的地壳速度结构特征比较接近。     

无盘网络系统的介绍和应用

无盘网络系统是一种很适合在计算机配置较固定、软件程序较划一的网络环境中运行的网络系统,随着电脑教育的规模扩大,网络教室的普及,发展也非常快.本文简述了其产生环境、功能介绍,针对其优势和不足说明了无盘网络系统的应用前景是非常广阔的.