Hierarchical self-assembly of p-terphenyl derivative with dumbbell-like amphiphilic and rod-coil characteristics

As water is gradually added, a p-terphenyl derivative with dumbbell-like amphiphilic and rod-coil characteristics can hierarchically self-assemble to metastable rectangle columns architecting sheets first and then to stable quasi-hexagonal columns architecting rolled sheets, and finally to rod-like nanostructures in MeOH/H₂O solution. Interestingly, the formed sheet, rolled sheet, and nanorod possess blue-light emitting property.     

Synthesis and morphology of triangular pyramid-shaped puerarin microparticle with nanostructure

<正>A type of triangular pyramid-shaped microparticles of puerarin was synthesized by using oil-in-oil microemulsion approach which is simple and economical under the action of copper substrate.The pyramid-shaped microparticles would be made up of deposit of nanospheres or nanorods and have two significant characters.One is its complex surface morphology like coral reef.The other is a lot of nanopores in existence in the microparticle body.Two possible formation routes were speculated.     

Analytical formulations of image forces on dislocations with surface stress in nanowires and nanorods

The interaction between dislocations and surfaces is usually characterized by image forces. Most analytical solutions to image forces could be found in literatures for two-dimensional (2D) solids with or without the consideration of surface stress. This work provides alternative analytical formulations of image forces for nanowires which are in more flexible forms compared with the infinite power series solutions from complex variable method. Moreover, this work proposes analytical formulations of image forces for nanorods (3D) by approximating the 3D shape effect as a height-dependent shape function, which is obtained through curve fitting of the finite element results of image forces without surface stress. The results of nanowires are demonstrated to be acceptable compared with the classical solution and complex variable method. More importantly, the analytical formulation of nanorods has not been found in other literatures so far. This work could contribute to nanostructure design and provide guidance for the fabrication of high quality nanostructures.     

Ripening and growth of zinc oxide nanorods from nanoparticles in 1,4 butanediol solvent

Zinc oxide nanorod formation in 1,4-butanediol was studied as a function of time and temperature using TEM and UV–Vis absorption spectra. Nanorod morphologies are formed by annealing of dilute nanodots, initially formed by sol–gel reaction in 1,4-butanediol. The nanorod morphology is unusual in the termination of the c-axis facets, with one end perpendicular to the a facets (flat) and the other faceted into a six-sided point. Ripening of nanodots proceeds via the Lifshitz–Slyozov–Wagner model of diffusion limited coarsening, and annealing at elevated temperature leads a transition to nanorod morphologies. Nanoparticle dissolution and shape development affect the axial ratio of the growing nanorods. Evidence of oriented attachment was not observed in the ripening study. The use of 1,4-butanediol allows for higher temperature reaction than in alcohols, without the use of pressure vessels.     

A facile approach to hexagonal ZnO nanorod assembly

Nanocrystalline ZnO nanorods were successfully grown by ultrasonication using an acidic ethanolic zinc acetate precursor solution followed by a flow coating process and annealing at 600 °C. The ZnO nanorods obtained were hexagonal in shape and showed a high degree of uniformity in size and distribution. These samples were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman spectrophotometry and the results are discussed. This approach appears to be the easiest way to fabricate bulk ZnO nanorods.     

Gd2O3∶Eu3+纳米棒的制备与发光性能

在表面活性剂辅助的水热条件下合成出尺寸均一的Gd2O3∶Eu3+纳米棒, 对其结构和荧光性质进行了表征, 并对其生长机理进行了初步讨论. XRD结果表明, 水热前驱体样品为六方晶相的Gd(OH)3, 经过灼烧之后样品为立方相的Gd2O3. TEM照片表明, 所得样品为直径60 nm、长度约600 nm的纳米棒. 荧光光谱表明, 在波长为254 nm 的紫外光激发下, Gd2O3∶Eu3+纳米棒产生了不同于前驱体的特征红光发射, 对应于Eu3+ 的5D0-7F2跃迁, 表明Gd2O3是红色发光材料的良好基质.     

Growth of aragonite calcium carbonate nanorods in the biomimetic anodic aluminum oxide template

In this study, a biomimetic template was prepared and applied for growing calcium carbonate (CaCO₃) nanorods whose shape and polymorphism were controlled. A biomimetic template was prepared by adsorbing catalytic dipeptides into the pores of an anodic aluminum oxide (AAO) membrane. Using this peptide-adsorbed template, mineralization and aggregation of CaCO₃ was carried out to form large nanorods in the pores. The nanorods were aragonite and had a structure similar to nanoneedle assembly. This aragonite nanorod formation was driven by both the AAO template and catalytic function of dipeptides. The AAO membrane pores promoted generation of aragonite polymorph and guided nanorod formation by guiding the nanorod growth. The catalytic dipeptides promoted the aggregation and further dehydration of calcium species to form large nanorods. Functions of the AAO template and catalytic dipeptides were verified through several control experiments. This biomimetic approach makes possible the production of functional inorganic materials with controlled shapes and crystalline structures.     

Preparation of zinc oxide nanorods using pulsed laser ablation in water media at high temperature

ZnO columnar single crystals were formed by pulsed laser ablation in deionized water and surfactant aqueous solutions of lauryl dimethylaminoacetic acid (LDA) and cetyltrimethylammonium bromide (CTAB) at 80 degrees C. ZnO particles produced by laser ablation were dissolved at a higher temperature than 60 degrees C, and then crystalline growth to columnar structure proceeded. While large ZnO columnar crystals were obtained in deionized water, the crystals prepared in surfactant solution were smaller than those in deionized water due to inhibition of crystalline growth by surfactant adsorption on ZnO surfaces. The size of ZnO nanorods depended on how surfactant molecules adsorb on ZnO surface.     

Controllable synthesis of highly ordered Ag nanorod arrays by chemical deposition method

Highly ordered Ag nanorod arrays were successfully fabricated using a simple chemical deposition method with the assistance of porous alumina membrane (PAM) template. The products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Ag⁺ ions in the PAM nanochannels were reduced by acetaldehyde reagent and resulting in the formation of rod array structures. It is found that the diameter of the Ag nanorods is determined by the PAM template, and the length of the Ag nanorods is depended on the reaction temperature. The growth mechanism of the Ag nanorod arrays is investigated in the study.     

Fabrication of hydroxyapatite and TiO2 nanorods on microarc-oxidized titanium surface using hydrothermal treatment

AC-type microarc oxidation (MAO) and hydrothermal treatment techniques were used to enhance the bioactivity of commercially pure titanium (CP-Ti). The porous TiO₂ layer fabricated by the MAO treatment had a dominant anatase structure and contained Ca and P ions. The MAO-treated specimens were treated hydrothermally to form HAp crystallites on the titanium oxide layer in an alkaline aqueous solution (OH-solution) or phosphorous-containing alkaline solution (POH-solution). A small number of micro-sized hydroxyapatite (HAp) crystallites and a thin layer composed of nano-sized HAps were formed on the Ti-MAO-OH group treated hydrothermally in an OH-solution, whereas a large number of micro-sized HAp crystallites and dense anatase TiO₂ nanorods were formed on the Ti-MAO-POH group treated hydrothermally in a POH-solution. The layer of bone-like apatite that formed on the surface of the POH-treated sample after soaking in a modified simulated body fluid was thicker than that on the OH-treated samples.