加拿大一枝黄花纤维素的改性及其对Cr(Ⅵ)的吸附

采用环氧氯丙烷和三甲胺对加拿大一枝黄花纤维素进行改性,改性后的加拿大一枝黄花纤维素对Cr(Ⅵ)具有一定的吸附作用.在改性加拿大一枝黄花纤维素加入量为3.2 g/L、吸附温度为40℃、吸附时间为240 min、溶液pH为2的条件下,对初始Cr(Ⅵ)质量浓度为20 mg/L的K2Cr2O7溶液进行吸附实验,Cr(Ⅵ)吸附量可达5.69 mg/g,Cr(Ⅵ)去除率为91％.动力学研究结果表明,改性加拿大一枝黄花纤维素对Cr(Ⅵ)的吸附以液膜扩散为控制步骤,反应过程符合Boyd液膜扩散方程,相关系数达到0.995 47.     

关于修改我国环境保护法的思考

当前,我国资源破坏和环境污染问题相当严重,要实现中国跨世纪环保政策目标和可持续发展战略,必须有健全的环境保护法律制度作保障。我国现行《环境保护法》制定于20世纪80年代末,已经不能适应现阶段的经济发展要求。本文从环境保护法的立法目的、基本原则、环境法律制度等方面对《环境保护法》的修改进行了论述。     

负载金属改性活性碳纤维的制备及其脱硫性能

以粘胶基活性碳纤维（VACF）为原料，采用浸渍法制备了负载镍、钴、锰、镁等系列金属的粘胶基活性碳纤维（M／VACF），并通过测定试样在77K的氮气吸附等温线对M／VACF比表面积和孔结构进行了表征。考察了M／VACF的脱硫性能，分析了影响其脱硫性能的各种因素。结果表明，M／VACF的比表面积和孔结构不是影响M／VACF脱硫性能的主要因素，负载金属的种类是影响M／VACF脱硫性能的主要因素。     

ACCIDENTAL AND PLANNED WEATHER MODIFICATION IN ILLINOIS1

ABSTRACT: Weather modification, both planned by man and that accidentally produced by man, has been under intensive study in Illinois for ten years. Most everyone in Illinois and the Midwest is living in a climate that now is modified inadvertently from its natural state. State atmospheric scientists have tackled weather modification through a series of interrelated studies beginning with climatic studies (to establish the background), experimental design studies, experimental field studies to verify changes and their causes, and finally socio-economic and environmental studies to measure the impacts of weather modification. Studies at St. Louis show that the city acts as a trigger of summer clouds and rainfall leading to 4 to 6 summer days with 3 cm or more rain somewhere just east of the city. Power plants and jet aircraft also accidentally produce climatic changes. A focus on planned weather modification has been on the design of needed midwestern experiments in rainfall enhancement and hail suppression including the societal and environmental impacts.     

NORTH AMERICAN INTERSTATE WEATHER MODIFICATION COUNCIL: NEED,GOALS, PURPOSE,AND ACTIVITIES1

ABSTRACT: A need for the prudent design and critical analysis of all weather modification efforts was expressed by the attendees of the June 1974 Governors' Weather Modification Conference in Sioux Falls, South Dakota. The attendees also expressed a need for an organization to coordinate and cooperate in intrastate, interstate and possible international weather modification activities, particularly in view of the growing importance of agricultural production, energy demand and domestic water supply. The North American Interstate Weather Modification Council (NAIWMC) was ratified on January 17, 1975, in Denver, Colorado, with its main purpose to achieve and maintain state and local control of such activities while endeavoring to attain a high degree of legislative uniformity and an effective information exchange mechanism. The need, goals, and objectives of the newly-created Council are summarized herein. The by-laws of the Council are presented according to the articles adopted at the organizational meeting. Membership in the Council is available to all states of the United States of America, Mexico, and all provinces of Canada. The officers of the Council are elected from its membership according to the regions of weather modification activities. A summary of the Council's progress at performing the purposes is presented in this paper. Definition of the users involved in the North American Interstate Weather Modification Council has been achieved during the early activities of the Council. The Council's views on federal and state weater modification legislation are presented according to position statements that have been adopted by the member states and provinces.     

HEAVY RAINFAL RELATIONS OVER CHICAGO AND NORTHEASTERN ILLINOIS1

ABSTRACT: Detailed studies of rainfall frequency and pattern relations were made over the Chicago urban region and the surrounding six Illinois counties (Cook, DuPage, Kane, Will, Lake, and McHenry). These studies utilized raingage records from an urban network of National Weather Service raingages in the region, primarily for the period 1949 to 1974. Frequency distributions of point rainfall were obtained for periods from 5 minutes to 72 hours and recurrence intervals of 6 months to 50 years. These results indicated a spatial pattern of short-duration heavy rainfall frequencies related to urban-lake effects, particularly in the huge industrial region over the southern portion of Chicago. The time distribution within heavy rainstorms over the urban region was determined, and it was found that the point rainfall relations over the urban region were similar to a 12-year sample of a dense raingage network over a rural area in central Illinois. The characteristics of heavy rainfall over northeast Illinois were also studied through the use of heavy, 1-day storms. A total of 87 storms, capable of producing local flooding, were analyzed to determine 1) the frequency distribution of storm centers, 2) seasonal and diurnal distribution of storms, and 3) orientation and movement of storms.     

ATMOSPHERIC CONTROLS OF WATER EXCHANGE IN GREAT LAKES BASIN1

ABSTRACT Existing meteorological controls of water exchange by precipitation and evaporation on the Great Lakes are almost entirely inadvertent and related to man's urban-industrial complexes and their effect upon precipitation processes. These inadvertent effects have led to 10 to 40% increases in precipitation in localized areas within the basin. Envisioned growth of urban-industrial complexes within the Great Lakes region should lead to more inadvertent weather modification in the Basin. The only existing planned weather modification efforts are those at Lake Erie which are attempting to eliminate by redistribution the concentration of lake-derived heavy snowfall along the south shore. It appears reasonable to assume that practical increases of lake precipitation on the order of 5-20% could be achieved on an operational basis over the Great Lakes in the next 10 years, but the time of accomplishment will depend on national priorities, international cooperation, and economic factors. These activities would certainly produce a sizeable increase in the water quantity of the Great Lakes and should result in an improvement in water quality. Operational methods of evaporation suppression applicable to the lakes are just not available. Meteorological controls to ameliorate certain undesirable lake-effect snowstorms are a near reality.     

ON PRECIPITATION SENSOR NETWORK DENSITIES FOR EVALUATING WINTERTIME OROGRAPHIC CLOUD SEEDING EXPERIMENTS1

Principal component analysis is used to investigate density requirements of wintertime orographic cloud seeding experiment precipitation sensor networks. Three passes in the vicinity of Climax, Colorado are studied. The eighteen or more evenly spaced precipitation sensors of each pass are almost completely described by three principal components. These three principal components appear to represent (i) mean precipitation, (ii) slope orientation to storm systems, and (iii) elevation. Evaluation of these principal components is implemented with two distribution-free tests, a proportionality test and the runs test. The results of this study suggest that the loss of experimental information caused by low density precipitation sensor networks may be of little consequence.     

Mechanical Properties and Lipase-Catalyzed Biodegradation of α-Methyl, ε-Caprolactone/ ε-Caprolactone Copolymers Obtained by Chemical Modification of Poly(ε-caprolactone)

Novel (-caprolactone)-based copolymers of different compositions were synthesized by allowing methyl iodide to react with the polycarbanion that resulted from the action of lithium diisopropylamide on poly(-caprolactone) in THF at –70°C under argon atmosphere. The copolymers were characterized by various techniques, namely ¹H nuclear magnetic resonance, size exclusion chromatography, differential scanning calorimetry, x-ray diffraction and viscoelasticimetry. They were submitted to hydrolytic and lipase-catalyzed enzymatic degradation in comparison with genuine PCL. The Young modulus depended on the degree of methylation. In contrast, loss angle and glass transition temperature did not depend on this parameter. It is shown that the lipase-catalyzed degradation of methylated PCL is much slower than in the case of genuine PCL.     

Biodegradation by Composting of Surface Modified Starch and PVA Blended Films

Several starch/PVA/glycerol polymer blends were prepared by a solution casting technique and examined for biodegradation by composting over 45 days. Within this time frame, the starch and glycerol components were fully degraded, leaving the PVA component essentially intact. The lowest PVA content film (20%) was selected as a polymer with enough PVA to impart important physical characteristics, but also enough starch to be considered biodegradable. The film characteristics were further improved by surface modification with chitosan. This modification did not interfere with the biodegradation of the starch component. Furthermore, there was slight evidence that PVA biodegradation had been initiated in composted, surface modified starch/PVA blends.