Mg-Nd-Zn-Zr镁合金表面超疏水SiO2薄膜的制备及其表征

以微弧氧化层(MAO)为预处理过渡层,正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)为主要原料,采用sol-gel和浸渍-提拉相结合的方法在Mg-Nd-Zn-Zr(NZ30K)镁合金表面获得甲基(-CH3)疏水基团表面修饰的超疏水SiO2薄膜,实现了NZ30K镁合金表面的超疏水改性.同时研究了微弧氧化层的表面特征、sol-gel过程中TEOS/乙醇摩尔比(TEOS/EtOH)和MTES添加量(MTES/TEOS摩尔比)对所制备超疏水SiO2薄膜表面形貌和润湿特性的影响.结果表明:NZ30K镁合金经过微弧氧化处理后,表面呈现的微米-纳米尺度上多孔的粗糙结构,其表面体现为亲水性,但有利于提高超疏水SiO2薄膜与NZ30K基材的结合力;当TEOS/EtOH摩尔比为1/30,MTES/TEOS摩尔比为1/2时,SiO2薄膜表面的静态接触角达到151°,其表面具有超疏水特性;而进一步提高MTES/TEOS摩尔比至1时,其静态接触角有所提高,达到153°.红外光谱(FT-IR)表明NZ30K镁合金表面SiO2薄膜的超疏水特性是由于MTES的引入使得-CH3疏水官能团能够成功地嫁接到SiO2粒子的表面.     

溶胶-凝胶法制备超疏水性OTS-SiO2复合薄膜

以正硅酸乙酯(TEOS)为先驱体,采用酸/碱两步溶胶-凝胶法和自组装技术制备了具有超疏水性的薄膜.利用红外光谱(FT-IR)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和接触角仪等测试方法对十八烷基三氯硅烷(OTS)修饰前后薄膜的结构、形貌、表面元素组成与润湿等性能进行了表征和分析.结果表明,制备的OTS-SiO2复合薄膜具有良好的超疏水性能,水滴在该薄膜上的最大静态接触角为156°,滚动角小于5°.     

一步喷涂法制备低黏附的超疏水颗粒表面

采用硬脂酸和十八烷基三氯硅烷分别对商业来源的ZnO、TiO2和SiO2颗粒进行修饰得到相应的疏水颗粒.然后利用简单的一步喷涂法通过喷涂所制备的疏水颗粒的无水乙醇悬浮液制备自清洁型的超疏水颗粒表面.通过红外光谱(FT-IR)、X-射线光电子能谱(XPS)、X-射线粉末衍射(XRD)证明低表面能物质成功地修饰在这些氧化物表面;用扫描电镜(SEM)观察超疏水表面形貌发现表面团聚现象比较严重;用DSA100型接触角测量仪测量所制备的超疏水颗粒表面对水滴的静态接触角高达160°,滚动角小于5°,说明该表面具有良好的超疏水性能.     

溶胶-凝胶法制备超疏水性OTS-SiO2复合薄膜

以正硅酸乙酯(TEOS)为先驱体,采用酸/碱两步溶胶-凝胶法和自组装技术制备了具有超疏水性的薄膜.利用红外光谱(FT-IR)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和接触角仪等测试方法对十八烷基三氯硅烷(OTS)修饰前后薄膜的结构、形貌、表面元素组成与润湿等性能进行了表征和分析.结果表明,制备的OTS-SiO2复合薄膜具有良好的超疏水性能,水滴在该薄膜上的最大静态接触角为156°,滚动角小于5°.     

涂层法制备超疏水表面及在油水分离中的应用

采用涂层法,以含硅聚四氟乙烯为成膜物质,以疏水纳米SiO2为填料,成功制备出含有微/纳米复合结构的超疏水表面.系统研究了疏水纳米SiO2和低表面能物质的含量与涂层表面水接触角的关系.采用接触角测量仪和扫描电子显微镜(SEM)分别对涂层的水接触角和表面形貌进行表征,根据国家标准分别对涂层厚度、硬度和结合力进行测试.在最佳制备条件下,该超疏水涂层水接触角153.5°,涂层厚度22μm,涂层硬度4H,结合力1级.该超疏水涂层具有自清洁及良好的油水分离性能.     

镁合金表面复合膜的制备及其耐蚀性

利用溶胶凝胶技术在镁合金微弧氧化膜表面制备SiO2溶胶凝胶膜形成复合膜层.通过扫描电镜和能谱测试,分析膜层的表面形貌和成分.采用动电位极化曲线测试研究不同条件下复合膜的电化学性能.研究结果表明:SiO2溶胶凝胶膜的最佳沉积条件为浸涂次数3次,浸泡时间1 min,干燥温度80～100℃,干燥时间8h,固化温度170℃,固化时间1h.溶胶凝胶膜能够有效地封闭镁合金表面微弧氧化膜的微孔,形成均匀且较为致密的复合膜层.动电位极化曲线结果表明:复合膜比微弧氧化膜和镁合金基体具有更正的腐蚀电位(Ecorr)、更低的腐蚀电流密度(icorr)和更大的线性极化电阻(Rp),说明微弧氧化镁合金沉积溶胶凝胶膜后耐腐蚀性能有显著地提高,复合膜对AZ91D镁合金具有良好的防腐蚀作用.     

气相法沉积PTFE薄膜及其疏水性

分别以载玻片、陶瓷片、镀铝聚酯膜、普通白纸和Cu片为基底,聚四氟乙烯(PTFE)粉末为原料,采用电子束蒸发法沉积聚合物薄膜。对于基底载玻片和陶瓷片,采用2%H2SO4溶液刻蚀预处理后在其上沉积厚度为125nm的聚合物薄膜;Cu片用不同浓度草酸刻蚀预处理后在其上沉积厚度为62 nm的聚合物薄膜;而基底镀铝聚酯膜和白纸,直接在其上沉积不同厚度的PTFE薄膜。通过傅里叶变换红外光谱仪(FT-IR)、原子力显微镜(AFM)、接触角测量仪分别对薄膜的成分、表面形貌和疏水性进行表征。结果表明:经刻蚀处理后,基底表面粗糙度皆增大。载玻片由亲水性转变为疏水性,陶瓷片无明显变化,Cu片显示良好的疏水性;沉积薄膜后,载玻片表面接触角增大到138°,而陶瓷片接触角可以达到142°;在粗糙度较大的白纸表面沉积不同厚度的PTFE薄膜,膜厚对接触角具有显著影响,当膜厚为225 nm时,接触角达到151°,滞后角为8°;经0.5%草酸刻蚀的Cu片表面膜的接触角达到153°,滚动角为2°,具有良好的超疏水性。     

PVA/SiO_2/HMDS薄膜的制备及性能研究

采用静电纺丝技术在玻璃基片表面构筑聚乙烯醇(PVA)纳米纤维网膜,以正硅酸丁酯(TEOS)为硅源,通过气相沉积法向PVA纳米纤维网膜间隙中引入SiO2纳米粒子。然后以六甲基二硅氮烷(HMDS)为修饰剂,对玻璃基片表面PVA/SiO2膜进行疏水改性,从而降低其表面能。利用扫描电镜(SEM),静态水接触角(WCA)等测试手段对在玻璃表面制备的PVA/SiO2/HMDS薄膜进行了表征。结果显示,处理过的玻璃基片具有较高的粗糙度,表面水接触角(WCA)达135.7°,表明其具有很好的疏水性能。而且制备的薄膜疏水性能稳定,耐磨性能好,能够保持较好的透明性。因此在高档室外墙体、汽车挡风玻璃、眼镜片等领域具有潜在的应用前景。     

PVA/SiO2/HMDS薄膜的制备及性能研究

采用静电纺丝技术在玻璃基片表面构筑聚乙烯醇(PVA)纳米纤维网膜,以正硅酸丁酯(TEOS)为硅源,通过气相沉积法向PVA纳米纤维网膜间隙中引入SiO2纳米粒子。然后以六甲基二硅氮烷(HMDS)为修饰剂,对玻璃基片表面PVA/SiO2膜进行疏水改性,从而降低其表面能。利用扫描电镜(SEM),静态水接触角(WCA)等测试手段对在玻璃表面制备的PVA/SiO2/HMDS薄膜进行了表征。结果显示,处理过的玻璃基片具有较高的粗糙度,表面水接触角(WCA)达135.7°,表明其具有很好的疏水性能。而且制备的薄膜疏水性能稳定,耐磨性能好,能够保持较好的透明性。因此在高档室外墙体、汽车挡风玻璃、眼镜片等领域具有潜在的应用前景。     

二氧化硅气凝胶改性方法及研究进展

为了提高采用溶胶-凝胶法制备的二氧化硅气凝胶的网络强度,介绍了对二氧化硅气凝胶进行改性的3种方法. 以正硅酸乙酯为硅源,采用溶胶-凝胶法和表面修饰工艺,在常压条件下制备了SiO2气凝胶. 傅里叶变换红外光谱仪(FT-IR)测试结果表明,SiO2气凝胶具有较好的疏水特性. 表面修饰剂三甲基氯硅烷在正己烷中的体积分数为6%,表面修饰时间为24h时,气凝胶具有优化的性能.     

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.     

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。     

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