四(4-磺基苯基)卟啉自组装催化剂的制备及其可见光光催化性能研究

本文以四(4-磺基苯基)卟啉(TPPS)与硝酸锌(Zn(NO3)2·6H2O)为原料制备了卟啉自组装催化剂(Zn-TPPS-Zn),利用紫外可见光谱对其进行光化学表征.在可见光下(λ≥420nm)照射下,以光催化降解染料罗丹明B(Rhodamine B,RhB)为探针反应,探讨了Zn-TPPS-Zn光催化过程中活化O2对RhB的光催化降解活性.实验表明,RhB光催化降解的最佳条件为:pH 6.89、催化剂投加量0.33g/L.催化剂循环实验表明Zn-TPPS-Zn在可见光下对RhB的降解具有一定的稳定性,但还需进一步改善.通过跟踪测定Zn-TPPS-Zn/RhB/Vis光催化反应体系中氧化物种(H2O2和·OH)相对含量的变化,表明其光催化反应主要涉及羟基自由基(·OH)历程.     

D301R树脂吸附Keggin型铁或铬取代杂多阴离子 光催化材料制备及其性能

用弱碱性阴离子交换树脂D301R对Keggin型铬取代磷钨杂多阴离子PW11O39Cr(Ⅲ)(H_2O)~(4-)(PW_(11)Cr)与Keggin型铁取代磷钨杂多阴离子PW_(11)O_(39)Fe(Ⅲ)(H_2O)~(4-)(PW_(11)Fe)进行吸附,制备了具有可见光响应的固体光催化剂。分别考查了所制备的光催化剂在均相及异相体系中对罗丹明B(RhB)降解的光催化活性。实验结果表明:当铁、铬离子取代的磷钨杂多阴离子同时存在时,RhB溶液的降解效率均高于单一金属离子取代的磷钨杂多阴离子光催化剂,并且异相体系的光催化效率高于均相体系。当催化剂D301R/PW_(11)Cr/PW_(11)Fe加入量为100 mg时,10μmol/L的RhB水溶液在可见光(λ 420 nm)照射50 min后,降解率可达92%。     

杂多酸盐在可见光照射下对染料的催化降解

将杂多酸(PW9Fe3)负载到阴离子交换树脂(Resin)上,得到PW9Fe3/Resin(PWFR)固相光催化剂,在可见光的照射下,可以有效地活化H2O2降解染料.以罗丹明B(Rhodamine B,RhB)为模型化合物,研究了不同条件下RhB 的降解动力学,以及降解过程中其UV-vis光谱及体系的总有机碳(Total Organic Carbon,TOC)变化情况,结果表明RhB的共轭芳环结构被破坏.催化剂的循环实验表明,PWFR 固相光催化剂易于分离,并且具有良好的稳定性,可以重复利用.     

PW/MCM-41光催化降解亚甲基蓝溶液研究

制备并表征了介孔分子筛MCM-41负载杂多酸H3PW12O40(PW)光催化剂.可见光照射下对模拟染料废水亚甲基蓝(MB)溶液进行了光催化降解实验,考察了影响催化降解的主要因素.结果表明:催化剂加入量为3.0g·L-1,MB初始浓度为10mg·L-1,pH=5时,在可见光照射下,亚甲基蓝溶液降解率最高可达92.57%.     

粘土负载铁异相光催化降解有机染料罗丹明B

通过将Fe3＋负载到经过煅烧的粘土（Clay）上制备复合型材料Fe-Clay（简称FeC）用作光催化剂,在可见光（λ＞420 nm）照射下,利用FeC光催化降解染料罗丹明B（Rhodamine B,RhB）,研究了光催化反应介质pH及H：O：加入量等因素对RhB降解特性的影响.结果表明,在可见光照射下,RhB/FeC/H2O2体系反应180 min后RhB的脱色率达100％,催化剂循环使用4次,其催化活性基本不变,可重复使用.     

PEG模板条件下BiOBr的制备及其光催化性能的研究

以表面活性剂聚乙二醇(PEG-6000)为模板剂,采用溶胶-凝胶法制备了溴氧化铋(BiOBr-PEG)光催化剂,运用XRD、SEM、BET和DRS对其结构及光化学特性进行了初步表征.在可见光(λ≥420nm)照射下,以有机污染料罗丹明B(Rhodamine B,RhB)和无色小分子水杨酸(Salicylic acid,SA)为目标化合物,研究了其光催化降解反应特性.结果表明:BiOBr-PEG具有优越的光催化活性,对RhB和SA都具有较好的降解效果,可见光照射40min和12h后,RhB和SA降解率分别达到98%和41%.同时,BiOBr-PEG催化剂稳定性良好,循环使用5次光催化活性基本稳定.光催化降解过程中涉及·OH和O·-2的氧化机理.     

CdS修饰ZnO可见光光催化降解有机污染物

采用直接沉淀法将硫化镉(CdS)沉积在氧化锌(ZnO)表面得到CdS/ZnO.运用SEM,XRD和UV-Vis DRS对催化剂进行表征.以罗丹明B(Rhodamine B,RhB)为目标化合物,研究了在可见光激发下(λ≥420nm)CdS/ZnO对目标污染物的光催化降解特性.结果表明:CdS/ZnO为棒状结构,最佳负载量在nCdS∶nZnO=20%条件下,其禁带宽度约为2.4eV,通过红外光谱(FT-IR)和总有机碳(TOC)的测定,发现该催化剂在可见光激发条件下能很好的降解RhB和水杨酸(salicylate,SA),在5h后对RhB脱色率达到90%以上,30h后对RhB的矿化率约为45%,对SA的降解率为67.6%.同时采用辣根过氧化物酶催化反应吸光光度法和苯甲酸荧光分析法跟踪分析测定RhB降解过程中H2O2和羟基自由基(·OH)的变化量,表明RhB降解机理涉及·OH历程.     

等离子体处理的Pd/BiOBr光催化剂及其光催化性能研究

以Bi(NO_3)_3·5H_2O和KBr为原料,采用水热合成法制备了BiOBr光催化剂.然后将制备好的BiOBr运用低温等离子体技术处理制备了Pd/BiOBr光催化剂.运用N_2-物理吸附脱附、X射线粉末衍射(XRD)、扫描电镜(SEM)对催化剂的结构和晶型进行了表征,利用光致发光(PL)谱、紫外可见漫反射吸收光谱(Uv-Vis DRS)技术和瞬时光电流谱对催化剂的光电特性进行了测定.并以染料罗丹明B(Rhodamine B,RhB)及无色小分子2,4-二氯苯酚(2,4-Dichlorophenol,2,4-DCP)为底物,在可见光(λ≥420nm)条件下考察了Pd/BiOBr的光催化降解性能,结果表明Pd/BiOBr催化剂较纯BiOBr光催化效果显著提升,在反应11h时对RhB矿化率达到70%.同时分析了BiOBr和Pd/BiOBr对RhB光催化降解过程中活性物种,表明BiOBr在降解过程中主要涉及O_2·~-氧化,Pd/BiOBr对RhB光催化降解过程中超氧和空穴同时起作用.     

H2O2敏化H3PW12O40/SiO2光催化降解甲基紫

采用溶胶-凝胶技术将Keggin型H3PW12O40负载在SiO2上,并用H2O2溶液对其进行敏化,制得H3PW12O40/SiO2/H2O2光催化剂.考察在模拟自然光条件下,甲基紫的初始浓度、溶液pH以及催化剂用量对甲基紫可见光催化降解率的影响.实验发现,在甲基紫初始浓度为30mg/L,溶液pH为2.5,催化剂的用量为0.6g/L的优化情况下,光降解2.5h,甲基紫的降解率达到92%.     

TiO2/Bi4V2O11复合光催化剂的制备及光催化性能

目的水热法制备TiO_2/Bi_4V_2O_(11)复合光催化剂并对其催化活性进行研究。方法采用XRD,BET,UV-Vis等表征手段研究催化剂的晶相结构和性能,并通过测试该复合结构对罗丹明B(Rhodamine B,RhB)的可见光催化降解评估其光催化活性。结果实验结果表明,复合物的光催化效果与纯的Bi_4V_2O_(11)和TiO_2光催化剂相比,TiO_2负载量为50%时,TiO_2/Bi_4V_2O_(11)复合光催化剂降解RhB具有更高的可见光催化活性。结论 TiO_2/Bi_4V_2O_(11)样品光催化性能的提高归因于增大了催化剂的比表面积以及TiO_2与Bi_4V_2O_(11)形成了异质结,从而有效抑制光生电子-空穴对的复合,并根据捕获实验提出了可能的光催化机理。     

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.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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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.     

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     

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.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme     

WIMAX与WI-FI技术分析及联合组网

介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。