中孔Ag微米盘/ZnO纳米棒阵列异质结的构筑及光催化研究

利用简单的两步合成法制备得到新颖的中孔Ag微米盘（HMDs）/ZnO纳米棒（NRs）异质结,主要包括上晶种和异质外延生长.通过简单的合成参数调控,可以制备不同纳米直径、不同长度、不同形状的ZnO NRs,进而制成不同形貌的Ag/ZnO异质结.结构新颖的Ag/ZnO异质结由一维（1D）半导体和二维（2D）纳米结构元构成,Ag/ZnO异质结具有高比表面积和开放的空间结构,在光电领域具有很重要的应用潜力.在光催化测试中,Ag/ZnO异质结表现出优越的催化活性,主要归因于结构独特的Ag/ZnO异质结的协同效应.     

叠层板自由边应力分析的状态空间法

从三维弹性力学基本方程出发,通过假设自由边的边界位移函数,建立了正交异性叠层板的状态方程,给出了对边自由,对边简支矩形板的解析解。此解计及了所有材料常数,且满足叠层板的基本方程和层间连续条件。为便于分析自由边的应力,该文根据叠层板的变形情况和边界条件假设位移函数,比较容易处理自由边条件。算例表明,数值结果具有较高的精度。     

正交异性板的后屈曲和Karman型精化理论

基于Ｋａｒｍａｎ型正交异性板的精化理论，本文采用挠度型摄动技术研究了复合构造矩形板的屈曲与后屈曲性态。分析中应用了由该理论导出的广义大挠度Ｋａｒｍａｎ方程，不仅考虑横向剪切，而且包含因材料指向性引起的剪弯相互作用。用此摄动技术构造出了四边简支正交异性中厚板和夹层板的后屈曲路径高阶渐展开式。通过比较可以看出，当前计算结果更接近相应的三维弹性理论精确解。     

Effect of Al2O3 and Y2O3 on the corrosion behavior of ZrO2-benzotriazole nanostructured coatings applied on AA2024 via a sol-gel method

zirconia-based nanostructured coatings were deposited on AA2024 to improve the corrosion resistance properties. Three different nanostructured coatings, namely, zirconia-benzotriazole, zirconia-alumina-benzotriazole, and zirconia-yttria-benzotriazole, were applied on AA2024 via a sol-gel method using the dip-coating technique. Next, the coatings were annealed at 150℃ after each dipping period. The phases and morphologies of the coatings were investigated using grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). The corrosion properties were evaluated using electrochemical methods, including polarization and electrochemical impedance techniques in 3.5wt% NaCl solution. The obtained results confirm the formation of homogeneous and crack free zirconia-benzotriazole-based nanostructured coatings. The average roughness values for zirconia-benzotriazole, zirconia-alumina-benzotriazole, and zirconia-yttria-benzotriazole nanostructured coatings were 30, 8, and 6 nm, respectively. The presence of alumina as a stabilizer on zirconia coating was found to have a beneficial impact on the stability of the corrosion resistance for different immersion times. In fact, the addition of alumina resulted in the dominance of the healing behavior in competition with the corrosion process of zirconia-benzotriazole nanostructured coating.     

交错轴圆柱端面齿盘共轭齿面的数值计算方法

提出了一种简单且精确的端面齿盘齿面数值计算方法，可用简单的直线和平面曲面段变点的求取，来代替复杂的啮合方程、过渡曲线方程的推导和求解。该方法只需圆柱齿轮参数、偏置距和传动比，就可以同时完成共轭齿面和过渡曲面的精确计算，并得到圆柱齿轮和齿盘啮合的瞬时接触线。通过对瞬时接触线的图形显示和分析，该方法可以优化设计参数，将空间共轭曲面的求解转化为平面曲线的计算，无原理误差，且简明、易于实现。     

一维纳米结构材料的水热合成:钒酸盐单晶纳米线和纳米带

一维纳米结构纳米棒、纳米线、纳米带和纳米管由于其独特的大小、形貌依赖的性质和作为纳米器件的重要组元和连接已经越来越受到广泛关注。钒酸盐晶体内在各向异性的多钒酸根长链结构和层状结构可能导致在合适溶液反应条件下控制生长成为一维纳米结构材料。基于以上考虑,一种简单容易的水热合成方法导致了预期的NaV60,6和NaV60,43H20单晶纳米线以及Nao.33Vi05nH:0 (n<1.3)单晶纳米带的控制生长。所有合成产物的相组成、结构和形貌分别通过XRD.SEM.TEM和SHED等分析技术进行分析和表征。因此,可以预期这种方法可能被应用于其它具有类似结构材料的一维纳米晶的合成。     

Porous cobalt oxide nanowires: Notable improved gas sensing performances

The porous Co3O4 nanowires have been successfully synthesized via modified template method. A possible growth mechanism governing the formation of such 1D nanowires is proposed. The as-prepared products have been characterized by X-ray Powder Diffraction (XRD), Extended X-ray Absorption Fine-structure (EXAFS), High-resolution Transmission Electron Microscopy (HRTEM) and N2 adsorption/desorption analysis. Our systematic studies have revealed that the porous Co3O4 nanowires show excellent gas sensing performances, which demonstrate the potential application of the 1D nanostructured Co3O4 in the detection of the ethanol gas as a sensor material. The improved performances are owing to its large specific surface area and porous morphology.     

管桩低应变检测中的三维效应分析

建立了三维柱坐标下桩土系统瞬态振动的计算模型,根据弹性动力学方程、边界条件和初始条件,确立了定解问题.利用交错网格有限差分法编制了相应计算程序,得出该定解问题的数值解,探讨了完整桩在竖向激振力作用下的瞬态动力响应,给出了桩顶不同位置的速度时程灰度图,并比较了桩顶与桩底各点竖向速度时程曲线的差别.基于管桩的低应变完整性测试数据,验证了该数值算法的可靠性及其反映波在管桩中传播的三维效应的可行性.在实际检测过程中,特别是在三维波动方程无法求得解析解的条件下,该数值计算结果具有一定的指导意义.     

肢体外形三维显示的曲线拟合法

在由二维图象作三维恢复的研究中，作者常采用加密网格、多角度摄象等方法来获取理想的数据，但常伴有较大误差．本文介绍：在适当阿格化、多角度摄象并作校正等图象预处理后，对网格节点作座标变换、相对纠偏、整序，然后再作物体表面外型线的三次样条拟合、插值，从而得到三维恢复．     

ITO/M3d-TiO2/CdS纳米结构多孔膜电极的光电化学

利用水热法制备了几种过渡金属离子(Zn2+、Co2+、Cu2+)掺杂的TiO2复合纳米粒子(表示为M3d-TiO2),测定了M3d-TiO2纳米结构多孔膜电极和用CdS敏化各掺杂电极的光电流作用谱和光电流-电势曲线.实验结果表明,在所研究的M3d-TiO2电极中,只有Zn2+-TiO2电极的光电流大于未掺杂的TiO2纳米结构多孔膜电极.用CdS敏化各掺杂电极,避免了电子损失,大大提高了光电转换效率,讨论了敏化电极的光电转换机理.     

氨基乙酸辅助化学液相沉积制备三维花状的氢氧化镁

以金属镁为前驱体,用生物分子氨基乙酸辅助化学液相沉积方法在室温下合成了具有复杂三维花状的纳米结构的氢氧化镁.用X-射线衍射(XRD)、扫描电镜(SEM)、红外光谱(IR)和热分析技术对所合成的三维氢氧化镁产物进行了微观形貌和微观结构的表征.结果表明纳米花状形貌的氢氧化镁是由超薄的纳米壁构成,并具有较高的纯度.对氨基乙酸辅助化学液相沉积法制备花状氢氧化镁的可能机理进行了研究.这种生物分子辅助化学液相沉积方法被很好地用来制备特殊形貌的氢氧化镁通过在液相中连续的供给、输运和分解镁络合物.这种方法具有反应条件温和、方便等特点,并有望拓展到制备其它具有不同形貌的金属氢氧化物/氧化物.     

Preparation of three-dimensional graphene foam for high performance supercapacitors

Supercapacitor is a new type of energy-storage device, and has been attracted widely attentions. As a two dimensional (2D) nanomaterials, graphene is considered to be a promising material of supercapacitor because of its excellent properties involving high electrical conductivity and large surface area. In this paper, the large-scale graphene is successfully fabricated via environmental-friendly electrochemical exfoliation of graphite, and then, the three dimensional (3D) graphene foam is prepared by using nickel foam as template and FeCl3/HCl solution as etchant. Compared with the regular 2D graphene paper, the 3D graphene foam electrode shows better electrochemical performance, and exhibits the largest specific capacitance of approximately 128 F/g at the current density of 1 A/g in 6 M KOH electrolyte. It is expected that the 3D graphene foam will have a potential application in the supercapacitors.     

三维流固两相流的颗粒群轨道柔性模型

为解决工程应用中三维流固两相流动力学建模的难题,提出了基于离散单元法(DEM)的颗粒群轨道柔性模型．即在Euler坐标系中表达流体连续相,在Lagrangian坐标系中运用DEM表达颗粒离散相,从而简单且有效地解决了三维流固两相流中颗粒相和流体相间的双向耦合和求解问题,同时以三维管道中气固两相流的建模和典型实例,可视化地说明了该方法的有效性．     

由铁鳞制备纳米氧化铁可见光光催化剂

以铁鳞为原料,采用水热法成功制备不同形貌的纳米Fe2 O3光催化剂。探讨了不同浓度的盐酸、液固比及反应时间对铁鳞浸出规律的影响。系统研究了铁鳞浸出液的纯度对于水热法制备纳米Fe2 O3的微观形貌和光催化性能的影响。结果表明：8 g铁鳞与150 mL浓度为3 mol·L-1的盐酸溶液在100℃回流反应2 h,铁鳞的浸出率达到约93%且浸出液纯度较高。浸出液中的杂质离子改变了纳米Fe2 O3的微观形貌和晶体的择优生长方向。另外,以铁鳞为原料制备出的纳米Fe2 O3可见光光催化性能较好,光降解罗丹明B溶液60 min后,其降解率可达87%左右。     

Polyaniline nanostructures tuning with oxidants in interfacial polymerization system

Three kinds of nanostructured polyanilines (PANIs) were prepared through interfacial polymerization by using ammonium persulfate (APS) as a single oxidant, and APS/FeCl3, APS/K2Cr2O7 as composite oxidants, respectively. It is observed that faster formation process and higher yield of nanostructured PANIs could be achieved in the presence of FeCl3 and K2Cr2O7. The as-prepared PANIs were characterized by field emission scanning electron microscopy, ultraviolet–visible absorption spectroscopy, Fourier transform infrared and Raman spectroscopy, X-ray diffraction analysis and electrochemical measurements including cyclic voltammetry and galvanostatic charge/discharge measurement. The influence of composite oxidants on the morphology, microstructure, and electrical and electrochemical properties of PANIs was discussed. Interestingly, when APS/K2Cr2O7 was used as the composite oxidants, PANI exhibited petal-like structure with high yield of 57.35% instead of general nanofibrous morphology formed in interfacial polymerization. Compared with those nanofibrous PANIs obtained by using APS as a single oxidant or APS/FeCl3 as composite oxidants, petal-like PANIs exhibited the largest specific capacitance (692.4 F/g at scan rate of 5 mV/s) and highest cycle stability among them. It provides a new insight into the control of PANI nanostructures with high yield and energy storage ability by simply selecting suitable composite oxidants in interfacial polymerization.     

一种事务处理原子性保证策略

讨论了多数据库系统中各个局部数据库管理系统不支持准备－提交操作时，在全局事务取消或失败的情况下，如何保证事务的原子性的问题．在一个系统中实现了重做、重试和补偿三种方法的有机结合     

多复变量的黎曼边值问题

利用Bochner-Martinelli型积分为工具,讨论Cn空间中具有逐块C(1)闭光滑边界流形的单连通区域D的黎曼边值问题,并在L*空间中给出了黎曼边值问题的唯一解.对此问题的特征之一是其边界系数不出现指标.     

Effect of heat treatment on microstructures and mechanical properties of a bulk nanostructured Al-Zn-Mg-Cu alloy

A bulk nanostructured Al-10.0Zn-2.8Mg-1.8Cu alloy was synthesized by cryomilling first and then by spark plasma sintering (SPS), and the effect of heat treatment on the microstructures and mechanical properties of this alloy were studied. Most MgZn₂ particles with a coarse size lie on the grain boundaries of the SPS-processed sample. After solid solution and artificial aging, fine spherical-like MgZn₂ particles precipitate uniformly in the grain interiors. No obvious grain growth is found after the heat treatment. A nanoindentation study indicates that no clear change is found in the Yong's modulus of the nanostructured alloy after the heat treatment. However, the hardness of the nanostructured alloy increases by about 33% after the heat treatment, which is attributed to the effect of precipitation-hardening.     

3D DNA origami designed with caDNAno

For about three decades, DNA-based nanotechnology has been undergoing development as an assembly method for nanostructured materials. The DNA origami method pioneered by Rothemund paved the way for the formation of 3D structures using DNA self assembly. The origami approach uses a long scaffold strand as the input for the self assembly of a few hundred staple strands into desired shapes. Herein, we present a 3D origami "roller" (75 nm in length) designed using caDNAno software. This has the potential to be used as a template to assemble nanoparticles into different pre-defined shapes. The "roller" was characterized with agarose gel electrophoresis, atomic force microscopy (AFM) and transmission electron microscopy (TEM).     

矩形外伸板的弹性分析

对于具有复杂边界条件的矩形外伸板,在弹性薄板理论中是一个较难解决的问题.使用了变相的或广义简支边的概念,将四周简支局部作用分布载荷矩形板的解、四周简支一边作用分布弯矩矩形板的解及各种具有广义简支边的矩形板的解进行叠加,并应用边界连续性条件,令这样的解满足所有边界条件,得到了任意载荷作用下矩形外伸板的解析解.作为算例,具体求解了外伸部分作用均布载荷的矩形外伸板,并与有限元结果进行了比较.所采用的方法,对于求解具有复杂边界条件板的解析解十分有效.