Synthesis and properties of lanthanide-based coordination polymers with carboxylate ligands

配位聚合物自上世纪80年代首次合成以来，由于其多样化的拓扑结构，和在光电、磁性、微孔和生物医学材料各领域的潜在应用，成为了近期的研究热点之一。因其以配位键作用为主，辅以分子间或者主客体的弱作用，这种组装方式使得配位聚合物结构丰富多样、性质易于预期和控制，因而以过渡金属的配位聚合物为主，被世界范围内的研究者广泛加以研究。 相对过渡金属配位聚合物，关于镧系金属的配位聚合物的研究较为滞后。然而因为镧系金属的配位聚合物的特殊配位性质和在荧光、磁性、催化、气体储存等方面的应用，以及它与过渡金属在同一体系的互动和竞争，镧系金属配位聚合物的调控组装、性质研究都是配位聚合物研究亟待解决的问题。本论文正是在此...Coordination polymers are attracting much interest because of their potential applications in optoelectronic, magnetic, microporous, and biomimetic materials, as well as of their versatile intriguing architectures and topologies. Compared with those of the transition-metal-based coordination polymers, the research focusing on the lanthanide-based polymers are rare, due to the relatively high coor...学位：理学博士院系专业：化学化工学院化学系_无机化学学号：B20042500

Electrocatalytic and Lifetime Studies of Commercial Catalystsin a PEMFC

　采用自设计的特制H 形电解槽模拟单个氢 空气质子交换膜燃料电池运作,并以电化学方法、SEM及XRD等技术研究两种商用催化剂,即碳载铂(Pt/C)和纯铂钌(Pt Ru)的电催化活性、表面形貌及其结构和寿命.同时对比了两种催化剂分别放在H 形电解槽和常规电解槽中运行情况的测试结果.实验表明,经过H 形电解槽运行后的催化剂,其循环伏安曲线表征氢吸脱的特征峰分别发生了正偏移(Pt/C电极)和负偏移(Pt Ru电极),且对应的峰电流呈现减小的趋势(特别是Pt/C电极).一氧化碳的毒化造成纯铂钌的电催化活性显著下降,其影响是不可逆的.A particularly designed H-type cell was used to simulate the operating condition of a hydrogen-air proton exchange membrane fuel cell (PEMFC). The electrocatalytic activity, morphology, structure and lifetime of commercially available catalysts, carbon support platinum (Pt/C) and unsupported platinum-ruthenium (Pt-Ru), were preliminary studied by carrying out electrochemical measurements and by SEM, XRD techniques. The catalysts were simultaneously tested in the H-cell under operation, and also separately tested in a conventional electrochemical cell for comparison. It was found that the characteristic peaks of hydrogen adsorption/desorption on cyclic voltammograms shifted considerably to a more positive direction for Pt/C, while a more negative direction for Pt-Ru. The magnitude of the peak current densities on CV curves, especially observed from Pt/C catalyst, tended to reduce after the lifetime tests. The electrocatalytic activity of Pt-Ru was significantly lower due to carbon monoxide poison, and the effect of CO on catalyst was irreversible.作者联系地址：厦门大学化学系固体表面物理化学国家重点实验室,厦门大学化学系固体表面物理化学国家重点实验室,厦门大学化学系固体表面物理化学国家重点实验室,厦门大学材料科学与工程系,厦门大学材料科学与工程系,厦门大学化学系固体表面物理化学国家重点实验室,厦门大学材料科学与工程系,美国气体技术研究院 福建厦门,361005 ,福建厦门,361005 ,福建厦门,361005 ,福建厦门,361005 ,福建厦门,361005 ,福建厦门,361005 ,福建厦门,361005 ,伊利诺伊斯60018Author's Address: *1, MA Yan-yun~1, QI Li~1, PENG Cheng~2, CHEN Ling~2, ZHAO Jun~1, ZHANG Ying~2,FAN Qin-bai~3 ysical Chemistry of Solid Surfaces,Xiamen University, Xiamen 361005,China, 2.Department of Materials Science & Engineering, Xiamen University, Xiamen 361005, China, 3. Gas Technology Institute,Des Plaines, IL 60018, US

secure web services discovery method based on access control

当前的Web服务发现机制大多依赖集中式的统一描述、发现和集成注册中心,但组织机构出于安全和地域的考虑,倾向于构建私有的分布式注册中心,只有注册且可信的请求者才能浏览到他们有权限访问的服务信息。该文给出Web服务发现阶段基于角色的访问控制模型RBAC4WSD,发现代理依照服务提供者指定的安全策略对请求者实施访问控制,并以跨国公司内部的文档服务为例介绍原型系统的实现

广州市至2020年城市客运交通发展情景分析

Submitted by CasirLion (casirlion) on 2009-12-03T17:15:03Z No. of bitstreams:

PEMFC商用催化剂电催化活性和寿命研究(英文)

　采用自设计的特制H 形电解槽模拟单个氢 空气质子交换膜燃料电池运作,并以电化学方法、SEM及XRD等技术研究两种商用催化剂,即碳载铂(Pt/C)和纯铂钌(Pt Ru)的电催化活性、表面形貌及其结构和寿命.同时对比了两种催化剂分别放在H 形电解槽和常规电解槽中运行情况的测试结果.实验表明,经过H 形电解槽运行后的催化剂,其循环伏安曲线表征氢吸脱的特征峰分别发生了正偏移(Pt/C电极)和负偏移(Pt Ru电极),且对应的峰电流呈现减小的趋势(特别是Pt/C电极).一氧化碳的毒化造成纯铂钌的电催化活性显著下降,其影响是不可逆的

硼团簇及其材料化学研究进展(I): 硼墨烯

位于元素周期表中的第五位元素硼, 其丰富的化学结构和多样的成键方式仅次于有机化学和生物科学中的核心元素——碳元素. 硼的缺电子性质导致其必须通过多中心键的方式共享电子以平衡体系的电子分布, 因此硼团簇多具有独特的几何结构和电子离域的成键特性. 近年来, 硼团簇及其材料的研究越来越受到人们的重视, 并取得了一系列研究成果. 通过实验和理论计算, 发现小尺寸的硼团簇多具有平面结构. 2014年, 王来生与李隽两个研究团队合作发现了中心含六元环孔的平面B36−团簇并由此提出了硼墨烯(borophene)概念, 为二维硼材料的发展提供了新的研究方向. 最近中美科学家同时在金属衬底上合成了单层硼墨烯, 使得二维硼材料备受关注. 鉴于硼的缺电子特性, 可以借助于金属掺杂等方式形成各种不同的金属硼化物结构. 具有完美平面结构的CoB18−团簇以及准平面的RhB18−团簇的发现推动了金属掺杂硼墨烯(metallo-borophene)研究的发展. 本文从实验和理论两个方面, 对具有平面或准平面结构的纯硼团簇、金属掺杂硼团簇、二维无限延伸硼墨烯材料等进行了介绍和总结, 并展望了硼团簇二维材料的研究前景和潜在应用. Boron, the fifth element in the period table, exhibits diverse bonding patterns and interesting structures due to its electron deficiency. Unlike its neighbor carbon, closed-packed boron sheet with graphene-like honeycomb lattice is unstable so that planar boron clusters usually have interior vacancies and corrugated appearance. Delocalized multi-center bonding has an important role to stabilize the 2D structures, giving rise to the concept of σ, π, …multiple aromaticity. The experimental observation of the B36− cluster in 2014 established the viability of boron monolayer which was named as “borophene” by Wang and Li. Recently, studies on planar CoB18− and RhB18− clusters have suggested the possibilities of metal-doped borophenes (metallo-borophenes) with potentially tunable electronic, magnetic and optical properties. In this review, we summarize recent experimental and theoretical advances in 2D pure-boron and metal-doped boron clusters, as well as their implications for borophenes and metalloborophenes as novel new boron materials

PEM FC 商用催化剂电催化活性和寿命研究

【Abstract】A particularly designed H-type cell was used to simulate the operating condition of a hydrogen-air proton exchange membrane fuel cell ( PEMFC) . The electrocatalytic activity, morphology, structure and lifetime of commercially available catalysts, carbon support platinum (Pt/C) and unsupported platinum-ruthenium (Pt-Ru) , were preliminary studied by carrying out electrochemical measurements and by SEM, XRD techniques. The catalysts were simultaneously tested in the H-cell under operation, and also separately tested in a conventional electrochemical cell for comparison. It was found that the characteristic peaks of hydrogen adsorption/ desorption on cyclic voltammograms shifted considerably to a more positive direction for Pt/C, while a more negative direction for Pt-Ru. T he magnitude of the peak current densities on CV curves, especially observed from Pt/ C catalyst, tended to reduce after the lifetime tests. T he electrocatalytic activity of Pt-Ru was significantly lower due to carbon monoxide poison, and the effect of CO on catalyst was irreversible.【中文摘要】采用自设计的特制H-形电解槽模拟单个氢-空气质子交换膜燃料电池运作,并以电化学方法、SEM及XRD等技术研究两种商用催化剂,即碳载铂(Pt/C)和纯铂钌(Pt-Ru)的电催化活性、表面形貌及其结构和寿命.同时对比了两种催化剂分别放在H-形电解槽和常规电解槽中运行情况的测试结果.实验表明,经过H-形电解槽运行后的催化剂,其循环伏安曲线表征氢吸脱的特征峰分别发生了正偏移(Pt/C电极)和负偏移(Pt-Ru电极),且对应的峰电流呈现减小的趋势(特别是Pt/C电极).一氧化碳的毒化造成纯铂钌的电催化活性显著下降,其影响是不可逆的

我国东北地区鼩鼱属物种的系统发生地位——基于线粒体COⅠ和16S rRNA分析

鼩鼱属（Sorex）动物分布广泛且与人类接触密切，但其较难捕获导致其系统分化关系并不明确，因此利用线粒体COⅠ和16S rRNA对采集自东北地区的9个鼩鼱属物种，以及从GenBank上下载的8种鼩鼱属的COⅠ序列和13种鼩鼱属的16S rRNA序列进行系统分化分析，计算遗传距离并构建系统进化树，探讨我国东北地区鼩鼱属的系统分化和分类学问题，进而明确其在鼩鼱属的系统发生地位。结果表明：分子系统学分析支持鼩鼱属应该分为主要分布于古北区的亚属（Sorex）和主要分布于新北区的亚属（Otisorex）。基于COⅠ测定的遗传距离为0050—0199，差别最大的是纹背鼩鼱（Sorex cylindricauda）和沼泽鼩鼱（Spalustris），而差别最小的是苔原鼩鼱（Stundrensis）和栗齿鼩鼱（Sdaphaenodon），新北区物种沼泽鼩鼱与其他物种的特化性较高，且符合地理分布。基于16S rRNA测定的遗传距离为0012—0128，差别最大的是扁颅鼩鼱（Sroboratus）与烟熏鼩鼱（Sfumeus），而西班牙鼩鼱（Sgranarius）和普通鼩鼱（Saraneus）的遗传距离最小，新北区物种假面鼩鼱（Scinereus）、烟熏鼩鼱和索绪尔鼩鼱（Ssaussurei）与其他物种的特化性较高，且符合地理分布。研究结果支持长爪鼩鼱（Sunguiculatus）与远东鼩鼱（Sisodon）亲缘关系很近；支持苔原鼩鼱和栗齿鼩鼱属于XY1Y2性染色体复杂种组；扁颅鼩鼱在系统发生地位上较为特化