The first two‐dimensional barium coordination polymer based on neutral and deprotonated 4‐formylbenzoic acid

A two‐dimensional barium(II) coordination polymer, [Ba(4‐FBA)₂(4‐FBAH)]_n (4‐FBA^? = 4‐formylbenzoate), has been synthesized by the reaction of barium carbonate and 4‐formylbenzoic acid. The barium(II) ion is nine‐coordinated by eight O atoms from six deprotonated 4‐FBA^? ligands and one O atom from the terminal 4‐FBAH ligand. Adjacent barium(II) ions are linked by the 4‐FBA^? ligand to furnish a two‐dimensional lamellar structure which exhibits blue fluorescent emission in the solid state at room temperature. Copyright © 2007 John Wiley & Sons, Ltd.     

A One-pot Procedure to Prepare Ethynylferrocene and Iodoethynylferrocene

IntroductionFerrocene-containing compounds have been widely used as important probes to investigate the electron transfer/transport properties of the molecular materials1. Recently, this technique was employed in molectronics research, where the ferrocenes were incorporated on the ends of conjugated molecular wires, and the electron transfer/transport abilities of the molecular wires were conveniently studied by electrochemical method2. Ethynylferrocene and iodoethynylferrocene were two import…     

硼化合物的研究(Ⅳ)——硼烷阴离子铵盐的合成与性质

通过硼烷阴离子网-B₃H₈^-和闭-B₁₀H₁₀^2-与一系列卤化铵反应合成出十五种新的硼烷阴离子铵盐。这些新化合物均经元素分析和红外光谱鉴定。它们的差热分析结果表明:B₁₀H₁₀^2-铵盐的热稳定性高于B₃H₈^-铵盐;在季铵离子中导入氨基以后,化合物的热稳定性降低,并且导入的氨基愈多,化合物愈不稳定。     

Nano-Sized NiO Immobilized on Au/CNT for Benzyl Alcohol Oxidation: Influences of Hybrid Structure and Interface

Tiny gold nanoparticles were successfully anchored on carbon nanotubes (CNT) with NiO decoration by a two-step synthesis. Characterizations suggested that Ni species in an oxidative state preferred to be highly dispersed on CNT. During the synthesis, in situ reduction by NaBH₄ and thermal treatment in oxidation atmosphere were consequently carried out, causing the formation of Au-Ni-O_x interfaces and bimetal hybrid structure depending on the Ni/Au atomic ratios. With an appropriate Ni/Au atomic ratio of 8:1, Ni atoms migrated into the sub-layers of Au particles and induced the lattice contraction of Au particles, whilst a higher Ni/Au atomic ratio led to the accumulation of NiO fractions surrounding Au particles. Both contributed to the well-defined Au-Ni-O_x interface and accelerated reaction rates. Nickel species acted as structure promoters with essential Au-Ni-O_x hybrid structure as well as the active oxygen supplier, accounting for the enhanced activity for benzyl alcohol oxidation. However, the over-layer of unsaturated gold sites easily occured under a high Ni/Au ratio, resulting in a lower reaction rate. With an Au/Ni atomic ratio of 8:1, the specific rate of AuNi₈/CNT reached 185 μmol/g/s at only 50 °C in O₂ at ordinary pressure.     

中温固体氧化物燃料电池复合阴极材料LSM-CBO的制备及性能研究

采用柠檬酸络合法为中温固体氧化物燃料电池制备了La0 .85Sr0 .15MnO3 Ce0 .7Bi0 .3 O2 (LSM CBO)复合阴极材料 ,利用XRD和SEM对材料进行了表征 .结果表明该复合材料在 10 0 0℃以内烧结时不发生反应 ,且在 90 0℃烧结 2h条件下 ,电极与Ce0 .9Gd0 .1O2 (CGO)电解质可形成良好的接触 .复合电极在 70 0℃ ,0 .6V阴极极化电势下处理 96h ,也没有发现可检测到的其它物相 .我们同时使用交流复阻抗谱和直流极化技术研究了电极的电化学性能 ,结果表明氧在电极表面的吸附是阴极反应的速率控制步骤 ,且随着CBO含量的增加电极极化电阻减小 ,最小值达到 2 2 3Ω·cm2 ,出现在掺杂 3 0wt %CBO的LSM复合电极中     

On the Clique-Transversal Number in （Claw,K4）-Free 4-Regular Graphs

A clique-transversal set D of a graph G is a set of vertices of G such that D meets all cliques of G.The clique-transversal number,denoted by τC(G),is the minimum cardinality of a clique-transversal set in G.In this paper,we first present a lower bound on τC(G) and characterize the extremal graphs achieving the lower bound for a connected(claw,K4)-free 4-regular graph G.Furthermore,we show that for any 2-connected(claw,K4)-free 4-regular graph G of order n,its clique-transversal number equals to [n/3].     

Electron Momentum Distributions for 4a1 Orbitals of CFxCl4-x in Low Momentum Region: a Possible Evidence of Molecular Geometry Distortion

由于低动量区域理论和实验的严重差异,重新分析了系列氟利昂分子CF₃Cl、CF₂Cl₂和CFCl₃ (CF_xCl_4-x, x=1～3)的4a₁轨道的电子动量分布. 利用分子离子的平衡几何构型计算得到的动量分布很大地改善了,与实验数据之间的吻合,这一结果表明在p<0.5 a.u.区域实验观测到的偏高的动量分布值可能是电离瞬间分子构型的扭曲带来的. 进一步的分     

激光直写制作的小F数连续浮雕衍射透镜轴向聚焦特性分析

为确定卷积效应以及深度制作误差对小F数连续浮雕衍射透镜(DOE)轴向聚焦特性影响,基于瑞利-索末菲衍射理论建立了激光直写制作的连续浮雕衍射透镜非旁轴近似轴向光强分布模型.该模型考虑了连续浮雕衍射透镜的轴向衍射聚焦特性与透镜结构参数、写入光斑尺寸和扫描间距以及深度制作误差的关系,克服了傍轴近似条件下传统模型的不精确性.为验证模型的正确性,用激光直写制作了设计波长为441.6 nm,F数为4以及相位匹配因子为3的连续浮雕衍射透镜,并测试了波长441.6 nm激光入射时透镜的轴向聚焦特性.实验与分析表明,该模型分析结果与实验测试结果符合,从而证实模型的有效性,为激光直写制作的小F数连续浮雕衍射透镜的应用提供了理论依据.     

阈值光电子-光离子符合成像研究NO+c3∏(v′=0)态解离动力学

用阈值光电子-光离子符合成像方法研究了处于c³∏(v′=0)态的NO⁺的光解离. 在使用垂直分子束的情况下,近似矢量加法规则推导了碎片离子在质心坐标系和最可几质心坐标系中的速度,飞行时间和在速度图像中的位移之间关系. 得到并讨论了N⁺碎片离子在质心坐标系中速度及在最可几质心坐标系中的速度和角度分布.     

Influence of double A1N buffer layers on the qualities of GaN films prepared by metal-organic chemical vapour deposition

<正>In this paper we report that the GaN thin film is grown by metal-organic chemical vapour deposition on a sapphire (0001) substrate with double AlN buffer layers.The buffer layer consists of a low-temperature(LT) AlN layer and a high-temperature(HT) AlN layer that are grown at 600℃and 1000℃,respectively.It is observed that the thickness of the LT-AlN layer drastically influences the quality of GaN thin film,and that the optimized 4.25-min-LT-AlN layer minimizes the dislocation density of GaN thin film.The reason for the improved properties is discussed in this paper.