固定化酶制备方法研究进展

对固定化酶的主要制备方法进行了系统的阐述,根据作者本人的试验经验对目前应用的研究得较多的方法作了详细的说明,对所阐述的各种固定化酶的制备方法的优缺点进行了比较。     

环境权架构的路径探析--兼论后现代主义对环境权研究的影响

环境权的研究遭遇着理论和实践的双重困境.若想摆脱困境,必须重新审视创设一项权利的相关基本理论,从而选择一条明晰的路径,有的放矢地架构权利内容.环境权创设的目的是保护自然环境的生态功能;环境要素生态功能的特征、市场和政府在环境保护方面的失灵以及环境法学的独立自足性论证了创设环境权的必要性;而将环境权定位于一项法律权利,并充分考虑其与现有权利的兼容性之后,提出了较为务实的架构环境权的制度取向.     

借助两个市场开发两种资源积极发展中国再生有色金属产业

在我国的工业化进程中,有色金属作为国民经济建设中不可或缺的基础材料,担当着十分重要的角色. 近年来,我国有色金属的年产量逐年递增,已成为位居世界第二的有色金属生产和消费大国. 虽然我国目前正处在产业结构大调整时期,但有色金属的年产量却始终以较高的速度增长,十分引人注目的是,在我国有色金属生产总量构成中,以各种各样的工业和民用废弃物为原料生产的再生有色金属的年增长速度始终比以原矿为原料的传统有色金属的年增长速度要快得多,这是个不争的事实.     

废旧电脑的综合处理与处置

随着社会文明的高速发展,越来越多的高科技新兴产品进入人们的生活,带给人们更多的方便和享受的同时,也使城市生活垃圾结构发生了很大的改变,废电池、废电冰箱、废电脑等家用电器及其废物的另类生活垃圾成为今天新的环境问题.从环境管理和绿色处理的角度,综合概述了国内外废旧电脑处理的现状,结合国外的发展经验从绿色处理的角度对废旧电脑的处理与处置方法提出了一些建议.     

论环保产业的法律保护

市场对环保产业的发展所起的作用是有限的,政府必须通过法律调控的方式引导环保产业的发展,当前的重点是建立有利于其发展的经济刺激法律制度.     

促进循环经济发展的税收对策

循环经济是一种全新的经济模式,它关注的是资源减量、循环及再利用的问题.通过对国外为实现循环型经济所采取的税收政策的比较,指出了我国目前在该领域采取的措施所存在的问题.根据我国的实际情况,提出了促进循环经济发展的税收对策.     

处理废水的膜工艺

美国公司开发了从工业废水中分离贵重组分的膜工艺,利用新型的可以把水分子分解成氢离子和氢氧离子的两极膜。盐溶液的水在表面上流过,通过外部带电的膜层向分离腔自由扩散,在分离腔内,水分解成氢离子和氢氧离子。在膜的间隙内,在电势的影响下,氧离子通过膜的一个外表层,而负的氢氧离子通过另一个外表层,因此,在两极的对面相反电荷的离子浓度增加。同时,沿两极膜两面分布的两个普通的单极离子交换膜,相反电荷的离于通过氢     

循环经济导向的废旧物资回收体系创新--基于我国社会经济发展进入加速转型期的基本判断

发展循环经济的基本原则之一是促进废旧物资的再生利用,因此废旧物资回收体系的建设是循环经济能否健康发展的重要环节.但是,目前废旧物资回收体系存在着种种不适应循环经济发展内在要求的制度性问题,这在很大程度上影响了循环经济的健康发展.在上述制度性问题分析的基础上,基于目前社会经济发展转型的基本判断,提出若干循环经济导向的废旧物资回收体系的制度创新的对策.     

面向经济回收的产品设计系统构成

面向回收的产品设计能够使废旧产品得到更好的回收和重用 , 优化拆卸序列的生成必须基于产品拆卸的经济性分析 . 论述了面向经济回收的产品设计系统的构成及相关的关键问题 , 分析了产品的零件材料回收价值与拆卸工艺 , 建立了零件材料合理回收的评估方法 .     

运用生物发光技术快速检测水体中毒物的初步探索

用自制的微弱光测试仪和华东师大生物系微生物教研室研制的海洋发光细菌冷冻干燥试剂,研究了石油化工废水中常见的六种有害物质对发光细菌的发光强度的抑制。探索运用发光强度抑制百分率来估求出单一的和综合毒物含量的可行性,进而对上海石化总厂各分厂的废水排放口的水样进行初步评价。     

Review of the kinetics of alkaline degradation of cellulose in view of its relevance for safety assessment of radioactive waste repositories

The degradation of cellulose (a substantial component of low- and intermediate-level radioactive waste) under alkaline conditions occurs via two main processes: a peeling-off reaction and a basecatalyzed cleavage of glycosidic bonds (hydrolysis). Both processes show pseudo-first-order kinetics. At ambient temperature, the peeling-off process is the dominant degradation mechanism, resulting in the formation of mainly isosaccharinic acid. The degradation depends strongly on the degree of polymerization (DP) and on the number of reducing end groups present in cellulose. Beyond pH 12.5, the OH^- concentration has only a minor effect on the degradation rate. It was estimated that under repository conditions (alkaline environment, pH 13.3-12.5) about 10% of the cellulosic materials (average DP = 1000-2000) will degrade in the first stage (up to 10⁵ years) by the peeling-off reaction and will cause an ingrowth of isosaccharinic acid in the interstitial cement pore water. In the second stage (10⁵-10⁶ years), alkaline hydrolysis will control the further degradation of the cellulose. The potential role of microorganisms in the degradation of cellulose under alkaline conditions could not be evaluated. Proper assessment of the effect of cellulose degradation on the mobilization of radionuclides basically requires knowing the concentration of isosaccharinic acid in the pore water. This concentration, however, depends on several factors such as the stability of ISA under alkaline conditions, sorption of ISA on cement, formation of sparingly soluble ISA-salts, etc. A discussion of all the relevant processes involved, however, is far beyond the scope of the presented overview.     

Study of Aging Characteristics of Ternary Blends of Polyethylenes—II

Six film samples of low-density polypropylene (LDPE)/linear LDPE (LLDPE)/high-density polypropylene (HDPE) with varying ratios of LDPE (20–45 ... wt%) and LLDPE (25–50 wt%) having a fixed amount of HDPE at 30 wt% were prepared by blown film extrusion technique. The samples were aged at four different temperatures, 55°, 70°, 85°, and 100°C, for four different time periods in the interval of between 150 hours and up to 600 hours. The change in the structure of various constituents and the formation of various oxygenated (peroxy and hydroperoxy) and unsaturated groups during thermo-oxidative degradation was discussed by infrared spectroscopy. The visiosity-average molecular weight was found to have decreased slowly in the initial aging hours and temperatures, whereas it decreased by 10% with its previous value tensile strength that is, 100°C when aged for 600 hours. The tensile strength of the sample first increased by 67% at 55°C and 89% at 70°C up to 450 hours, whereas the values increased by 52.5% at 85°C and 33.9% at 100°C when aged for 150 hours and then decreased. The percentage elongation at break increased by 2.7% at 55°C and 10.7% at 70°C for 150 and 300 hours of aging, respectively, whereas the percentage decreased when aged at 85°C and 100°C for up to 600 hours of aging. The values of gel content (percent) increased and initial degradation temperature decreased with aging time and temperature.     

Determination of the Burning Characteristics of a Slick of Oil on Water

The burning rate of a slick of oil on a water bed is characterized by three distinct processes, ignition, flame spread and burning rate. Although all three processes are important, ignition and burning rate are critical. The former, because it defines the potential to burn and the latter because of the inherent possibility of boilover. Burning rate is calculated by a simple expression derived from a one-dimensional heat conduction equation. Heat feedback from the flame to the surface is assumed to be a constant fraction of the total energy released by the combustion reaction. The constant fraction (χ) is named the burning efficiency and represents an important tool in assessing the potential of in situ burning as a counter-measure to an oil spill. By matching the characteristic thermal penetration length scale for the fuel/water system and an equivalent single layer system, a combined thermal diffusivity can be calculated and used to obtain an analytical solution for the burning rate. Theoretical expressions were correlated with crude oil and heating oil, for a number of pool diameters and initial fuel layer thickness. Experiments were also conducted with emulsified and weathered crude oil. The simple analytical expression describes well the effects of pool diameter and initial fuel layer thickness permitting a better observation of the effects of weathering, emulsification and net heat feedback to the fuel surface. Experiments showed that only a small fraction of the heat released by the flame is retained by the fuel layer and water bed (of the order of 1%). Ignition has been studied to provide a tool that will serve to assess a fuels ease to ignite under conditions that are representative of oil spills. Two different techniques are used, piloted ignition when the fuel is exposed to a radiant heat flux and flash point as measured by the ASTM D56 Tag Closed Cup Test. Two different crude oils were used for these experiments, ANS and Cook Inlet. Crude oils were tested in their natural state and at different levels of weathering, showing that piloted ignition and flash point are strong functions of weathering level.     

Calculation of carbon balances for evaluation of the biodegradability of polymers

Establishing carbon balances has been proven to be an applicable and powerful tool in testing biodegradability of polymers. In controlled degradation tests at a 4-L scale with the model polymer poly(-hydroxybutyrate) (PHB), it was shown that the degree of degradation could not be determined with satisfactory accuracy from CO₂ release alone. Instead, the course of degradation was characterized by means of establishing carbon balances for the degradation of PHB withAcidovorax facilis and a mixed culture derived from compost. Different analytical methods for determining the different carbon fractions were adapted to the particular test conditions and compared. Quantitative determination of biomass and residual polymer were the main problems in establishing carbon balances. Amounts of biomass derived from protein measurements depend strongly on assumptions of the protein content of the biomass. Selective oxidation of biomass with hypochlorite was used as alternative, but here problems arose from insoluble metabolic products. Determination of soluble components with the method of chemical oxygen demand (COD) also includes empirical assumptions but seems acceptable if the dissolved carbon fraction is in the range of some 10% total carbon. Results confirm both analytical assays and theoretical approaches, in ending up at values very close to 100%, within an acceptable standard deviation range under test conditions comparable to standard test practice.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.     

Model of technological alternatives of production of sodium chromate (VI) with the use of chromic wastes

This article presents a mathematical model which describes the sodium chromate (VI) production process with the use of chromic waste as a substitution of natural raw materials. This model is a function of selected process parameters common for all of the examined alternatives and based on equations of material balance. Optimization of the elaborated technological alternatives of the production process with use of recycling of chromic waste has been evaluated by determining the extreme value of the quality indicator WJ. This indicator defines the quantity of waste created in the process. Optimization results enabled the selection of the optimal technological solution from all of the alternatives possible for use in industrial practice. Negative values of the indicator prove that there is the possibility of introducing to the process a larger quantity of waste than the one obtained in the process and transported to the storage heaps.     

化学品生物降解性的评价与预测

介绍了有机化学物质生物降解性的测定方法及其预测方法研究概况，并讨论了生物降解性评价的发展前景。     

鼓泡式反应器高径比对氨法烟气脱碳性能的影响

以N2和CO2混合气模拟燃烧烟气,研究了鼓泡反应器的高径比以及反应条件对氨法烟气脱碳性能的影响。实验结果表明:在相同高径比的条件下,CO2吸收率随氨水质量分数的增加、反应温度的升高而逐渐增大,随进气CO2体积分数和模拟烟气流量的增加而逐渐减小;CO2吸收率随高径比的增加而增大,在高径比为3.98、氨水质量分数为28%、进气CO2体积分数为10%、模拟烟气流量为1.0L/min、反应温度为40℃的条件下,CO2吸收率最高可达100%。     

Mechanism of Microbial Degradation of Slow-Release Fertilizers

Methyleneureas are condensation products of urea and formaldehyde of different molecular mass and solubility; they are used in large amounts both as resins, binders, and insulating materials for industrial applications, as well as a slow-release nitrogen fertilizer for greens, lawns, or in bioremediation processes. In the present study, the microbial breakdown of these products was investigated. The nitrogen was released as ammonia and urea, and the formaldehyde released immediately oxidized via formiate to carbon dioxide. The enzymatic mechanism of metabolization of methyleneureas was studied in microorganisms isolated from soil, which were able to use these compounds as the sole source of nitrogen for growth. A strain of the Gram-negative bacterium Ralstonia paucula (formerly Alcaligenes sp. CDC group IVc-2) completely degraded methylenediurea and dimethylenetriurea to urea, ammonia, formaldehyde, and carbon dioxide. The enzyme initiating this degradation (methylenediurease) was purified and turned out to be different from the previously described enzyme from Ochrobactrum anthropi with regard to its regulation of expression and physicobiochemical properties. Fungal degradation of methyleneureas may occur via the formation of organic acids, thus leading to a nonenzymatic degradation of methyleneureas, which are unstable under acidic conditions.     

Structure-biodegradation relationships of polymeric materials. 1. Effect of degree of oxidation on biodegradability of carbohydrate polymers

The biodegradability of oxidized starch and inulin has been studied in relation to the degree of periodate oxidation to dialdehyde derivatives, by measuring oxygen consumption and mineralization to carbon dioxide. A higher degree of oxidation of dialdehyde starch and dialdchyde inulin results in a lower rate at which the polymers are biodegraded. It is demonstrated that the biodegradation rate of dialdehyde inulin derivatives decreases more than that of equivalent starch derivatives. The differences in biodegradation behavior between dialdehyde starch and dialdehyde inulin, resulting from comparable modifications, are discussed in terms of conformational structure.     

Effect of Degree of Substitution of Octenyl Succinate Starch on Enzymatic Degradation

Octenyl succinate starch of degree of substitution (ds) 0.03, 0.07, and 0.11 was synthesized in an aqueous medium. These compounds were then tested for the susceptibility to enzymatic degradation. The multiple-enzyme regime of -amylase, amyloglucosidase, and pullulanase was chosen for the evaluation. This combination of enzymes had been proven to degrade 99.5% of unmodified starch to glucose and hence was chosen for this study. It was found that even small amounts of subsituent caused a considerable decrease in the extent of degradation. The net extent of degradation decreased with increasing ds. Surprisingly, the amount of glucose from all three substituted substrates was quite similar, suggesting the effect small amounts of subtituent had on the enzymatic activity.