检索结果-南通市图书馆

Synthesis of todorokite by refluxing process and its primary characteristics

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science china Earth Sciences 2004年第8期47卷 760-768页

作者： FENG Xionghan1, LIU Fan1, TAN Wenfeng1, LIU Xiangwen2 & HU Hongqing1 1. college of resources and environment, huazhong agricultural university, wuhan 430070, china 2. Testing Center, china university of Geosciences, wuhan 430074, china college of resources and environment Huazhong Agricultural University Wuhan China Testing Center China University of Geosciences Wuhan China

Single phase and well-crystallined todorokite were synthesized by heating and refluxing process from birnessite as a precursor. The average chemical composition of the synthesized todorokites by refluxing for 8 h and for 24 h was Mg0.19MnO2.11(H2O)1.15 and in0.17-MnO2.10(H2O)0.88, respectively. The crystallinity of the todorokite increased and no other phase was produced with increasing refluxing period. The synthesized todorokites have the same morphologies and the similar structural characteristics with the natural todorokites and hydro-thermally synthesized samples. The chemical compositions of the synthetic tordorokites by refluxing process are close to those of todorokites synthesized by hydrothermal process, except a higher average oxidation state of Mn for the former.

关键词： todorokite,birnessite,manganese oxide,refluxing,hydrothermal,synthesis.

Pathways of birnessite formation in alkali medium

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2005年第9期48卷 1438-1451页

作者： FENG Xionghan1, TAN Wenfeng1, LIU Fan1, HUANG Qiaoyun1 & LIU Xiangwen2 1. college of resources and environment, huazhong agricultural university, wuhan 430070, china 2. Testing Center, china university of Geosciences, wuhan 430074, china college of resources and environment Huazhong Agricultural University Wuhan China Testing Center China University of Geosciences Wuhan China

Birnessite is a common weathering and oxidation product of manganese-bearing rocks. An O2 oxidation procedure of Mn(OH)2 in the alkali medium has been used to synthesize birnessite. Fast and powder X-ray diffraction (XRD), transmission electron microscopy (TEM), electron diffraction (ED), energy dispersed X-ray analysis (EDAX), infrared spectroscopy (IR) techniques and chemical composition analysis, Eh-pH equilibrium diagram approaches were employed to investigate the reaction process and pathways of birnessite formation. Results showed that the process of the birnessite formation could be divided into four stages: (1) forma- tion stage for hausmannite and feitknechtite, (2) stage of transformation of hausmannite and feitknechtite to buserite, (3) buserite crystal growing stage, and (4) stage of conversion of buser- ite into birnessite. Mn(OH)2 was mainly present as amorphous state only for a short initial time of oxidation reaction. In the oxidation process, buserite formed following two pathways by recrys- tallization after dissolution of the intermediates, and the transformations of the minerals de- pended on the Eh determined by the dissolved O2 concentration on their surfaces. The results are fundamental in further exploration on the mechanism of birnessite formation in the alkali medium. A great practical significance would also be expected with respect to the areas of mate- rial sciences.

关键词： birnessite, pathway of formation, reaction process, Eh-pH diagram, hausmannite, feitknechtite.

Factors governing formation of todorokite at atmospheric pressure

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2005年第10期48卷 1678-1689页

作者： CUI Haojie1, FENG Xionghan1, LIU Fan1, TAN Wenfeng1 & HE Jizheng2 1. college of resources and environment, huazhong agricultural university, wuhan 430070, china 2. Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing 100085, china huazhong agricultural university Chinese Academy of Sciences

Todorokite commonly occurs in Earth surface environments. The factors governing formation of todorokite, such as reaction temperature, metal ions, dissolved O2 and pH, were investigated in this paper. Results showed that the forming rate of todorokite and its crystallinity decreased with falling reaction temperature, and the effect of temperature was more significant than that of other parameters. Nature of metal ions in the interlayer of buserite precursor and the structure of the buserite precursor obviously affected buserite transformation into todorokite. Weak bonding between the metal ions and MnO6 layer of buserite was favorable to todorokite formation. The rate of todorokite formation was promoted at a lower temperature with appropriate bubbling of O2. The pH in the system slightly influenced the todorokite formation, and todorokite could also be formed in a weak alkali medium or in a slightly acidic medium. Aged buserite pre-cursor more easily form todorokite than the unaged one.

关键词： todorokite, buserite, manganese oxide mineral, atmospheric pressure, transformation.

Binding and Transformation of Extracellular DNA in Soil

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2005年第1期15卷 16-23页

作者： CAIPeng HUANGQiao-Yun ZHANGXue-Wen CHENHao StateKeyLaboratoryofagriculturalMicrobiology CollegeofResourcesandEnvironmentHuazhongAgricultureUniversityWuhan430070China StateKeyLaboratoryofagriculturalMicrobiology CollegeofResourcesandEnvironmentHuazhongAgricultureUniversityWuhan430070China／／CollegeofScienceHuazhongAgricultureUniversityWuhan430070China collegeofScience HuazhongAgricultureUniversityWuhan430070China

DNA is the genetic material of various organisms. Extracellular DNA adsorbed or bound on surface-active particles in soils has been shown to persist for long periods against nucleases degradation and still retain the ability to transform competent cells. This paper reviews some recent advances on the binding and transformation of extracellular DNA in soils, which is fundamental to understanding the nature of the soil, regulating biodiversity, and assessing the risk of releasing genetically engineered microo…

关键词： adsorption binding extracellular DNA soil transformation

SCGM(1,m)_c model with time-lag and its application in deformation analysis

在线全文

学校读者我要写书评

暂无评论

Journal of Central South university of Technology 2001年第1期8卷 40-44页

作者： LI Zhi wei 1, LI Tao 1,zhu Jian jun 1,WANG Ren qian 2 (1.college of resources, environment and Civil Engineering, Central South university, Changsha 410083, china 2.Department of Civil Engineering, Huaqiao university, Quanzhou 350029, china) college of resources Environment and Civil Engineering Central South University Changsha China Department of Civil Engineering Huaqiao University Quanzhou China

Originated in the early 1990s, SCGM(1, m ) c model has enjoyed widespread application in the fields of urban planning, society economy prediction and modal control in recent years. However, none of these applications have taken account of time lag effects in the modeling process. Aiming at overcoming the defect, the authors introduced time lag items into SCGM(1, m ) c model and developed a SCGM(1, m ) c model with time lag, then discusses in detail some principal problems in the model, such as parameters estimation, model verifying, model prediction, etc. The model was used on a real slope monitoring project and compared with the conventional SCGM(1, m ) c model. The results show an improvement of average models precision from 1.321 to 0.238 and total average of relative prediction errors from 12.41% to 7.98% when the modeling data length ranges from 29 to 48 in the slope monitoring case.

关键词： grey system SCGM(1,m)c time-lag deformation analysis

Paleoenvironmental reconstruction and organic matter accumulation of the paleogene shahejie oil shale in the Zhanhua Sag, Bohai Bay Basin, Eastern china

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第3期21卷 1552-1568页

作者： Xiao-lin Wang Xiao-Min zhu Jin Lai Xing-Yue lin Xiang Wang Yu-Shan Du Chao Huang Yu-Rui zhu State Key Laboratory of Petroleum resources and Engineering China University of Petroleum(Beijing)Beijing102249China college of Geosciences China University of Petroleum(Beijing)Beijing102249China Shengli Oilfield SINOPECDongying257000ShandongChina

The controlling factors of organic-rich shale accumulation is essential for the exploration and development of shale oil and gas *** sedimentary environment plays a vital role in the formation of organic-rich sediments in lacustrine *** article unravels the mineralogy,geochemistry,and paleoenvironmental evolution during the deposition of the Paleogene Shahejie Formation(Es_(3)^(L)).It discusses the effects of paleoclimate,paleosalinity,paleoredox conditions,paleowater depth,and paleoproductivity on organic matter(OM)***,the OM enrichment model was *** results show that the mineralogical compositions are mainly composed of calcite(avg.40.13%),quartz(avg.21.64%)and clay minerals(avg.24.07%),accompanied by dolomite(avg.7.07%),feldspar(avg.6.36%)and pyrite(avg.2.95%).The Es_(3)^(L) shale has a high abundance of OM,with total organic carbon(TOC)ranging from 1.07%to 5.12%.The organic matter type is mainly composed of type I-II_(1) kerogen,which is generally considered a good-quality source *** source of OM is a mixture of lower bacteria,algae,and *** the early sedimentary period,the paleoclimate was dry and cold,with high salinity,intense reducibility,and relatively low *** the late sedimentary period,the climate became warmer and more *** a result,the salinity decreased to a level that was suitable for biological reproduction,and productivity increased gradually due to the input of terrigenous *** and paleoclimate determined the environment of the sedimentary period,in addition,paleoproductivity and paleoredox condition indicated the formation and preservation conditions of *** warm and humid climate,brackish water,suitable reduction conditions and high productivity are the favorable conditions for the generation and preservation of organic *** research results may have implications for the genetic mechanisms of organic matter *** will provide theoret

关键词： Elemental geochemical Paleoenvironment Organic matter accumulation Paleogene shahejie formation Zhanhua Sag Bohai Bay Basin

Immobilization of an enzyme from a Fusarium fungus WZ-I for chlorpyrifos degradation

在线全文

学校读者我要写书评

暂无评论

Journal of environmental Sciences 2010年第12期22卷 1930-1935页

作者： Hui Xie,Lusheng zhu,Tingting Ma,jun Wang,Jinhua Wang,jun Su,Bo Shao college of resources and environment,Shandong agricultural university,Taian 271018,china college of resources and environment Shandong Agricultural University Taian 271018 China

The free enzyme extracted from WZ-I, which was identified as Fusarium LK. ex Fx, could effectively degrade chlorpyrifos, an organophosphate insecticide. The methods of immobilizing this free enzyme and determined its degradation-related characteristics were investigated. The properties of the immobilized enzyme were compared with those of the free enzyme. The optimal immobilization of the enzyme was achieved in a solution of 30 g/L sodium alginate at 4℃ for 4-12 hr. The immobilized enzyme showed the maximal activity at pH 8.0, 45℃. The maximum initial rate and the substrate concentration of the immobilized enzyme were less than that of the free enzyme. The immobilized enzyme, therefore, had a higher capacity to withstand a broader range of temperatures and pH conditions than the free enzyme. With varying pH and temperatures, the immobilized enzyme was more active than the free enzyme in the degradation reaction. In addition, the immobilized enzyme exhibited only a slight loss in its initial activity, even after three repeated uses. The results showed that the immobilized enzyme was more resistant to different environmental conditions, suggesting that it was viable for future practical use.

关键词： organophosphate pesticide immobilized enzyme degradation fungus

Adsorption and Insecticidal Activity of Toxin from Bacillus thuringiensis on Rectorite

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2007年第4期17卷 513-521页

作者： ZHOU Xue-Yong HUANG Qiao-Yun CAI Peng YU Zi-Niu Hubei Province Key Laboratory of Refractories and Ceramics Wuhan University of Science and Technology Wuhan 430081 （China）. college of Biotechnology and Chemical Engineering Tianjin University of Technology Tianjin 300191 （China） State Key Laboratory of agricultural Microbiology College of Resources and Environment Huazhong Agricultural Uni- versity Wuhan 430070 （China）

The adsorption and desorption of the toxin from Bacillus thuringiensis strain WG-001 on rectorite were studied at different toxin and/or rectorite concentrations, pH values and temperatures. The insecticidal activity of the adsorbed toxin was evaluated by determining the lethal concentration to kill 50% of the larvae of Heliothis armigera （LC50）. The adsorption of the toxin on rectorite in sodium carbonate buffer （pH 9） reached equilibrium within 0.5-1.0 h and the adsorption isotherm of the toxin followed the Langmuir equation （R^2 〉 0.99）. In the pH range from 9 to 11 （carbonate buffer）, the adsorbed toxin decreased with increasing pH. The adsorption amounts decreased with increasing rectorite：toxin ratio. The adsorption was not significantly affected by the temperature between 10 and 50 ℃. The X- ray diffraction analysis indicated occurrence of the intercalation of the rectorite by the toxin. The infrared absorption spectrum showed that the binding of the toxin did not alter its structure. The LC50 wlues of the adsorbed toxin were smaller than those of the free toxin. The rectorite protected the toxin from ultraviolet irradiation damage. The desorption of the adsorbed toxin in water ranged from 37.5% to 56.4% and from 27.4% to 41.8% in a carbonate buffer. The desorption percentage also decreased with increasing rectorite：toxin ratio.

关键词： Bacillus thuringiensis insecticidul uctivity rectorite toxin udsorption und desorption

Research on Indicator System of Regional Eco-efficiency:A Case Study of Chengyang District

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Population,resources and environment 2006年第4期4卷 54-58页

作者： Zhou Zhenfeng1,2,Sun Lei2,Sun Yinglan2 1.college of resources&environment,Laiyang agricultural college,Qingdao,Shandong 266109,china 2.School of environmental Science and Engineering,Ocean university of china,Qingdao,Shandong 266003,china college of resources & environment Laiyang Agricultural College Qingdao Shandong 266109 China School of environmental Science and Engineering Ocean University of China Qingdao Shandong 266003 China School of Environmental Science and Engineering Ocean University of China Qingdao Shandong 266003 China School of Environmental Science and Engineering Ocean University of China Qingdao Shandong 266003 China

Eco-efficiency is a valuable tool for managing and solving issues involving resource consumption and pollution emission in current production *** the popularity of the term"eco-efficiency"in business,limited attention has been paid to measuring and reporting regional eco-efficiency for local government policy *** on the concept and method of eco-efficiency,an indicator system of regional eco-efficiency is established in this *** indicator system comprises 22 indicators,which are divided in to three categories including socio-economic development,resources consumption, environmental *** a promising statistical technique, principle component analysis is used to set the weight of indicators which attempts to calculate the eco-efficiency indices of Qingdao's Chengyang *** results show that the eco-efficiency of Chengyang District has clearly improved 35.1% with small fluctuation from 1995 to ***-economic development index and resources consumption index also represent obvious increasing *** correlation coefficient between soci-economic development index and resources consumption index is 0.979,which means the social progress and economic growth of Chengyang District depend on an extravagant consumption of *** environmental pressure index increased slowly before 1997 and declined gradually after 1997,due to more attention being paid to environmental protection by local government in recent *** District still keeps the traditional economic development mode with a high consumption and high production,so the emphases of future development should put on improving the improving the efficient use of natural resources and promoting environmental management *** results show that the indicators system of regional eco-efficiency is a promising method to quantitatively evaluate resources and environmental efficiency and provide an effective decision-making support for local governments.

关键词： regional eco-efficiency indicator system Ecoefficiency Synthetic Index (ESI) Principle Component Analysis (PCA)