Journal of Nano Research Vol. 25

Abstract: Highly ordered Anodic Aluminum Oxide (AAO) structures produced from aluminum by using an electrochemical anodizing method were developed towards its application for the next generation of micro/nanomedical and energy devices. In addition of analyzing the anodizing current profile, the surface morphology was characterized by using Scanning Electron Microscopy (SEM), the crystalline structure by X-Ray Diffraction (XRD) and the mechanical properties by nanoindentation experiments. The anodizing time and applied potential determines the nanopores regularity and their size, although the effect of the potential is more pronounced than the effect of temperature in the transformation from crystalline alumina to amorphous alumina. Optimum pore growth was achieved with an applied potential of 17 V which led to a pore fraction - P(f) - of about 17.5%. The experimental Berkovich nanoindentation method was used to determine the AAO hardness as a function of the indenter depth, during the loading stage, using mechanical response and deformation behaviour of the nanopores structure. From the experimental data of the load-displacement curves, this method allows the calculation of the indenter contact depth at each reloading point, thus leading to the estimation of the materials hardness. The results reveal that the hardness depends on the processing conditions used for the production of the AAO samples that also strongly influences the organization and pore size uniformity.

Abstract: The effects of nanoparticles (nanoclay and nanosilicon dioxide) on heat sealability, physicochemical, barrier, and mechanical properties of starch films were investigated. Starch films were prepared by casting method with addition of nanoparticles and plasticizers. All film properties were measured under standard conditions. Mechanical properties of all types of films were increased by incorporation of nanoparticles. Mungbean starch films showed 100% increment in tensile strength by incorporation of nanoclay. Moisture content, water solubility, and WVP of all starch films decreased whereas decomposition temperature of the films was increased by incorporation of nanoparticles. All films were heat sealable, but nanoparticles-incorporated films exhibited better heat sealability than did control films. In summary, the type of starch governed the heat sealability but nanoparticles have potential to improve seal strength of starch films as well as other functional properties.

Abstract: In-situ characterization of the mechanical behavior of geckos spatula has been carried out in detail using multi-mode AFM system. Combining successful application of a novel AFM mode, i.e. Harmonix microscopy, the more detail elastic properties of spatula is brought to light. The results obtained show the variation of the mechanical properties on the hierarchical level of a seta, even for the different locations, pad and stalk of the spatula. A model, which has been validated using the existing experimental data and phenomena as well as theoretical predictions for geckos adhesion, crawling and self-cleaning of spatulae, is proposed in this paper. Through contrast of adhesive and craw ability of the gecko on the surfaces with different surface roughness, and measurement of the surface adhesive behaviors of Teflon, the most effective adhesion of the gecko is more dependent on the intrinsic properties of the surface which is adhered.

Abstract: Copper-substituted cobalt ferrite nanoparticles were prepared via a sol-gel route using citric acid as a chelating agent. The influence of copper concentration on the microstructure, crystal structure and antibacterial property of copper-substituted cobalt ferrite nanoparticles against E. coli and S. aureus has been systematically investigated. The results indicate that the substitution of copper influences strongly the microstructure, crystal structure, particle diameter and antibacterial property of cobalt ferrite nanoparticles.

Abstract: Polylactides (PLA) based composite films modified with nanoclay content ranges from 0-30 wt% were fabricated using solvent casting method and the mechanical properties, water vapor permeability, oxygen barrier, thermal stability and optical properties were studied. The study showed that the addition of up to 15 wt% of clay has caused a significant improvement of tensile strength of the PLA/nanoclay composite film. However, the further increasing of nanoclay content of >15 wt% of nanoclay has caused a significant reduction in tensile, elongation at break and optical properties of PLA matrix. Both the oxygen and water permeability of the PLA/nanoclay composite film decrease with the increasing of nanoclay contents. Greater water barrier properties would be achieved if the high nanoclay contents of 10-30 wt% were dispersed homogenous within the PLA matrix. The addition of nanoclay greater than 10 wt% affected the appearance of the film (i.e. increasing the haze and ΔE). Thermal analysis result has proved that the melting temperature, crystallization temperature and glass transition temperature of the composite film only slightly affected by the addition of nanoclay due to the immobilization polymer chain in the composite film.

Abstract: Removed at authors request.

Abstract: Removed at authors request

Abstract: In this study, piezoelectric actuator, flexure guide, power transmission element and control method are considered for nanopositioning system apparatus. The main objectives of this thesis were to develop 2-axis nanostage which enables 2-axis control with the aid of piezoelectric actuator, and to improve the precision of the ultra-precision lathe (UP2) which is responsible for the ductile mode machining of the hardened-brittle material where the machining uses a the single-crystal diamond. Through simulation and experiments on ultra-precision positioning, stability and priority of the nanopositioning system with 2-axis nanostage and control algorithm are developed using Matlab/Simulink. Then the system, is applied to analyze surface morphology of the titanium alloy (Ti-6Al-4V)

Abstract: Micro metal injection molding has become the promising method in powder metallurgy research in order to fabricate small-scale intricate parts in an influential process and competitive cost of mass production. Stainless steel 316 L powders with powder size of 150 nm and 5 μm were mixed with a binder with a water soluble component which consisted of a major fraction of water soluble Polyethylene Glycol (PEG), a minor fraction of polymethyl-methacrylate (PMMA) and some stearic acid has been used as a surfactant. This work aims to investigate the rheological properties of a feedstock which are efficiently characterised by capillary Rheometry to measure apparent viscosities at different temperatures and shear rates. Results obtained by the varying feedstock characteristics, when viscosity decreases by increasing of shear rate at certain temperature feedstock should have a pseudoplastic behaviour. Melt viscosity of the feedstock was decreased by adding nanoscale powders. The reduced (n) values at high temperature with addition of nanoparticles indicated a possible increase in the shear-thinning behavior.