TiO2光催化降解水中喹诺酮类抗生素

研究TiO2光催化降解水中3种喹诺酮类抗生素的动力学特征,探讨TiO2用量、初始浓度、pH和水质对3种喹诺酮类抗生素光催化降解的影响。研究结果表明:当优化参数为TiO2用量1.0 g/L、抗生素初始浓度10 mg/L,pH=7时,反应80 min,3种喹诺酮类抗生素的降解率均在95%以上;光催化降解反应符合假一级反应动力学方程,反应速率常数为0.044 5~0.071 0,半衰期为9.76~15.57 min,降解难易程度从高到低的顺序为诺氟沙星、环丙沙星、洛美沙星;不同水质中诺氟沙星、环丙沙星的降解率从高到低的顺序为高纯水、河水、自来水,而洛美沙星的降解率从高到低的顺序为河水、自来水、高纯水。     

活性污泥对2种喹诺酮类抗生素的吸附特征

为揭示活性污泥对喹诺酮类抗生素的吸附特征,采用静态吸附实验法研究活性污泥吸附环丙沙星(CIP)、氧氟杀星(OFL)的吸附动力学、吸附热力学和pH值影响.研究结果表明:CIP和OFL吸附动力学符合准二级动力学模型,吸附过程受颗粒内扩散和膜扩散共同影响;Freundlich吸附等温线可较好描述活性污泥对CIP、OFL的吸附特性;ΔG~θ、ΔH~θ及ΔS~θ均为负值,吸附过程为自发、放热、熵减过程;pH7时,溶液pH升高,活性污泥对CIP、OFL吸附能力逐渐减弱,pH≥7时,吸附能力快速减弱.研究结论可为喹诺酮类抗生素在活性污泥处理工艺中的行为及归趋研究提供科学依据.     

泥沙质量浓度和pH对不同粒径泥沙吸附磷影响研究

以北京大兴南海子湖表层沉积物为研究对象,测试分析了粒径φ0.246mm、泥沙在含沙质量浓度为5、10、30、50g·L-1对磷的吸附过程,以及细砂(0.147～0.246 mm)、极细砂(0.074～0.147 mm)、粉粒(0.038 5～0.074 0mm)和粉粒粘粒混合物(≤0.038 5mm)4种粒径泥沙在不同pH值条件下对磷的吸附行为.研究结果表明:二级动力学方程能够比较理想地反映南海子泥沙对磷的吸附动力学过程(R20.98),吸附平衡时单位质量泥沙饱和吸附量由大到小排序为:粉粒黏粒混合物(0.107mg·g-1)、粉粒(0.096mg·g-1)、细砂(0.095mg·g-1)、极细砂(0.051mg·g-1)·pH值对极细砂、粉粒、粉粒黏粒混合物影响相似,pH值为4～10之间,吸附量变化不大,在pH10时,吸附量降低,pH4时,吸附量升高.在磷初始质量浓度ρ01.2mg·L-1时,随着泥沙质量浓度增大水溶液中磷吸附的绝对量升高,从最大吸附容量(Xm)来看,单位质量泥沙吸附磷量降低,泥沙之间对磷的吸附存在竞争且与磷初始质量浓度有关.     

硫酸根自由基降解氟喹诺酮抗生素动力学模型构建

针对水环境中广泛残留的氟喹诺酮类抗生素污染问题,采用热激活过硫酸盐方式降解3种典型氟喹诺酮抗生素(环丙沙星、诺氟沙星、恩诺沙星),考察其在不同pH下的降解情况,构建相关自由基动力学氧化模型,并将数学模型与实验数据相耦合计算体系中特征自由基的浓度及目标物拟二级动力学反应常数。研究结果表明:建立的模型能够较好地描述氟喹诺酮微观反应动力学,反应体系中·SO_4~-及·HO浓度受pH影响较大,环丙沙星、诺氟沙星、恩诺沙星与·SO_4~-反应的二级动力学常数分别为6.96×107±2.31,2.52×10~7±4.47和8.55×10~7±1.98L/(mol·s)。     

利用天然泥沙去除水体中重金属影响因素分析

重金属在水体中有很强的吸附性,可利用天然泥沙的吸附作用去除水体中重金属,但吸附剂、吸附质以及环境介质条件对吸附量和去除率(K)有很大影响.本文利用相关文献数据,进行标准化处理后,采用曲线拟合的方法,分别分析了污染物初始浓度、泥沙含量、泥沙粒级、pH值、温度、离子强度等影响因素对K的作用规律,结果显示:(1)初始浓度、泥沙颗粒粒径、离子强度值越大,K越低;(2)泥沙含量越高,K越高,并存在最佳泥沙含量值;(3)pH增大,K增大,曲线分快、平、快三阶段;(4)温度越高,K呈线性增长.在此基础上本文建立了影响因素与K间的综合模型,验证结果显示计算值与实测值间相对误差为0.21%—3.57%.该模型可为去除水环境中重金属的工程条件优化提供参考依据.     

蒙脱石对喹诺酮类抗生素的吸附平衡及动力学特征

以蒙脱石为吸附剂进行水中2种喹诺酮类抗生素(环丙沙星和诺氟沙星)的静态吸附试验,考察初始浓度、pH值和阳离子强度对吸附性能的影响.结果表明,蒙脱石对环丙沙星和诺氟沙星的吸附过程均符合二级反应动力学方程,吸附速率常数分别为0.063和0.024 kg·mg-1·h-1.环丙沙星和诺氟沙星的吸附等温线均能较好地符合Freu...     

Fenton氧化法降解洛美沙星的研究

针对水体中普遍存在的喹诺酮类抗生素,选择洛美沙星(Lomefloxacin,LOM)作为研究对象,采用Fenton氧化法对其进行降解,并深入研究了以下4个因素:Fe2+初始浓度、H2O2初始浓度、初始pH值、LOM初始浓度对降解行为的影响。通过单因素实验并综合考虑成本效益筛选出最适宜的反应条件,即选取pH=6.5,Fe2+初始浓度、H2O2初始浓度分别为0.1 mmol/L,0.5 mmol/L,处理初始浓度为50μmol/L的LOM水溶液,反应5 min后LOM的去除率达到89%。umu试验结果显示在Fenton氧化降解LOM过程中,体系的遗传毒性在反应初期迅速降低,之后降低速度减缓,同时体系的抗菌活性也随着反应进行逐渐降低。     

甲硝唑自然光降解研究

药物与个人护理品(PPCPs)是一类近期引起普遍关注的环境“新型”微污染物.PPCPs的大量使用和排放造成环境中的持久性存在.光化学降解是水环境中PPCPs微污染物的重要消减途径.本文中以武汉地区夏秋太阳光为光源,研究甲硝唑的自然光降解行为.考察不同因素,即水质、pH、常见离子、初始浓度对甲硝唑光降解的影响,同时以紫外光源作对照.实验结果表明,甲硝唑在太阳光下迅速自接光降解;甲硝唑的初始浓度越大,光降解速度越慢;光源的强度越大,且波长越接近于目标物的最大吸收波长时,降解速度越快.     

光催化降解四环素类抗生素废水影响因素分析

抗生素是一种具有潜在生态风险的污染物,含抗生素的废水难降解,并且包含大量的生物抑制性物质,对于以生化处理为主的污水处理厂有一定的处理难度.基于多位学者对光催化技术去除污水中四环素类抗生素的研究,总结其现状以及pH、废水初始浓度和催化剂用量对降解率的影响.结果表明:光催化技术对四环素类废水具有良好的降解效果,降解率高达80%以上,并且可循环使用,稳定性好.pH在5～9范围对光催化降解有提升作用,强酸强碱体系对光催化反应有抑制;抗生素废水的初始浓度与降解率成反比;降解率与催化剂的投加量成正比关系,随投加量的增加先快速上升,随后逐渐趋于平缓.     

臭氧降解水中氯霉素影响因素及机制研究

抗生素在水环境中具有高毒性和难生物降解性的特点,污水处理厂普通的处理工艺很难将其降解,抗生素通过生物富集等方式在生物体内累积,给生物健康及生态平衡带来严重威胁.文章利用臭氧技术对水体中氯霉素(chloramphenicol,CAP)降解效果评估.考察CAP的初始质量浓度、臭氧质量浓度、初始pH值以及自由基清除剂对CAP...     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to