A novel approach for real mass transformation from V2O5 particles to nanorods

A solid-state, mass-quantity transformation from V2O5 powders to nanorods has been realized via a two-step approach. The nanorods were formed through a controlled nanoscale growth from the nanocrystalline V2O5 phase created by a ball milling treatment. The nanorods grow along the [010] direction and are dominated by {001} surfaces. Surface energy minimization and surface diffusion play important roles in their growth mechanism. Real large quantity production can be achieved when the annealing process is conducted in a fluidized bed which can treat large quantities of the milled materials at once. The crystal orientation of nanorods provides an improved cycling stability for lithium intercalation.

Superhydrophobic modification of polyimide films based on gold-coated porous silver nanostructures and self-assembled monolayers

We present a facile and effective method for controlling the surface hydrophobicity of polyimide films from sticky to superhydrophobic properties by tailoring their topographies. Nanostructured silver layers were produced on polyimide films by treatment with aqueous KOH and AgNO3, followed by thermal treatment at 200 degrees C or higher temperatures. Further modification of the gold-coated silver layers with n-dodecanethiol led to hydrophobic surfaces. Different morphologies of the silver layers at the micro- and nano-meter scales, which result in the variety of hydrophobicity, can be tailored by controlling the thermal treatment temperature. Surfaces prepared at 320 degrees C showed a sticky property that water drops did not slide off even when the sample was held upside down. Superhydrophobic surfaces were obtained when the temperature was above 340 degrees C. A remarkable superhydrophobicity, as evidenced by a very large water contact angle of 162 degrees and a very small sliding angle of 7 degrees, was achieved by heating the modified polyimide films at 360 degrees C. This is also the first example for superhydrophobic modification of polyimide films.

Metamorphosis of a gold town : Stawell 1900-1940 : a study in local history

Examines the experience of the Wimmera town of Stawell as being representative of the early settlements created by gold rushes, and then threatened with extinction as the industry declined. Attention is paid to the role of community in Stawell's struggle to survive in the period between Federation and the Second World War. Reviews the economic and social processes involved in the eventual recovery. Argues that the forces of Stawell's historical legacy can be detected in the town's reaction to adversity after the closure of the last major mine in 1920.

Titanium oxide nanorods extracted from ilmenite sands

One dimensional titanium oxides (TiO2) nanorods and nanowires have substantial applications in photocatalytic, nanoelectronic, and photoelectrochemical areas. These applications require large quantities of materials and a production technique suitable for future industry fabrication. We demonstrate here a new method for mass production of TiO2 nanorods from mineral ilmenite sands (FeTiO3). In this process, powder mixtures of ilmenite and activated carbon were first ball milled; the milled samples were then heated twice at two different temperatures. First high-temperature annealing produced metastable titanium oxide phases, and subsequent second low-temperature annealing in N2-5%H2 activates the growth of rutile nanorods. This solid-state growth process allows large-quantity production of rutile nanorods.

Event effectiveness : analysing the perceptions of key stakeholders of the Lexmark Indy 300/champ car event, Gold Coast.

The present study assessed the perceptions of the Lexmark Indy 300/Champ Car Event’s key stakeholders namely, spectators, volunteers and paid workers, as part of an evaluation tool for its managers. We developed a model, which included visible, interaction and management elements that we proposed influenced the perceptions and experiences of stakeholders relating to the event effectiveness, strengths, weaknesses and improvements. Specifically, we used a modified version of Preble’s (2005) six-step multi-stakeholder assessment approach to examining the perceived overall effectiveness of the event. Fifty stakeholder interviews were conducted on-site and their opinions were content analysed. The key findings of the study were that the majority of the stakeholders perceived the event to be effective. Spectators perceived the strengths to be interaction components, and weaknesses and improvements to be visible elements such as track layout. Volunteers perceived strengths to be management related, but also noted that these were weaknesses and needed improvement. Lastly, Paid workers perceived interaction elements to be both strengths and weaknesses, and suggested that management elements could be improved. Important implications for similar motoring events were suggested.

Ionic liquid-assisted synthesis of polyaniline/gold nanocomposite and its biocatalytic application

In this report, a novel chemical synthesis of polyaniline/gold nanocomposite is explored using ionic liquid (IL) 1-Butyl-3-methylimidazolium hexafluorophosphate. The direct chemical synthesis of polyaniline/gold nanocomposite was initiated via the spontaneous oxidation of aniline by AuCl4 − in IL. A nearly uniform dispersion of polyaniline/Au particles with a diameter of 450 ± 80 nm was produced by this method, which indicates that this method is more suitable for controlling particle dimensions. It was also found that the electrical conductivity of the polyaniline/gold nanocomposite was more than 100 times higher than that of the pure polyaniline nanoparticles. The polyaniline/gold nanocomposite displays superior function in the biocatalytic activation of microperoxidase-11 because of the high surface area of the assembly and the enhanced charge transport properties of the composite material. We also report the possible application of polyaniline/gold nanocomposite as a H2O2 biosensor.

Stepwise synthesis of Gly−Gly−His on gold surfaces modified with mixed self-assembled monolayers

Peptide-modified electrode surfaces have been shown to have excellent recognition properties for metal ions. An efficient method of screening a potential peptide for its selectivity for a given metal would involve the synthesis of the peptide directly on the electrode surface. This paper outlines a procedure in which the tripeptide Gly−Gly−His was synthesized one amino acid at a time on a gold surface modified with a self-assembled monolayer of the mixed alkanethiolates 3-mercaptopropionic acid (MPA) and 3-mercaptopropane (MP). Electrochemistry and high-resolution mass spectrometry were used to elucidate the structure of the adsorbed species and follow the synthesis. The amino acids can be attached only to MPA, but the presence of a diluting unreactive molecule of MP reduces steric crowding about the reaction center. The maximum coverage of synthesized tripeptide occurs at a ratio of MPA/MP of 1:1.

Characterisation of gold electrodes modified with self-assembled monolayers of l-cysteine for the adsorptive stripping analysis of copper

Electrochemical sensors for copper ions in environmental samples were prepared by modifying gold electrodes with l-cysteine by self-assembly. The adsorption of l-cysteine on gold electrodes was studied by electrochemical reductive desorption in 0.5 M KOH, and the interaction of l-cysteine with copper ions was investigated by cyclic voltammetry, chronoamperometry and X-ray photoelectron spectroscopy. At low concentrations the ratio of l-cysteine to bound Cu(II) is 2:1. At higher concentrations (0.1 M) copper reacts with adsorbed cysteine forming copper sulfide on the electrode surface. On a modified l-cysteine gold electrode, Osteryoung square wave voltammetric determination of Cu(II) with a detection limit below 5 ppb has been demonstrated.

Fast colorimetric detection of copper ions using L-Cysteine functionalized gold nanoparticles

This communication reports an efficient visual detection method of Cu²⁺ by L-cysteine functionalized gold nanoparticles in aqueous solution. Upon exposure to Cu²⁺, the gold nanoparticle solution changed from red to blue, in response to surface plasmon absorption of dispersed and aggregated nanoparticles. This colorimetric sensor allows a rapid quantitative assay of Cu²⁺ down to the concentration range of 10⁻⁵ M. Recognition of Cu²⁺ and formation of the aggregates are proposed to occur via a 2 : 1 sandwich complex between L-cysteine and Cu²⁺.

Redox voltammetry of sub-parts per billion levels of Cu2+ at polyaspartate-modified gold electrodes

An electrochemical sensor for the detection of Cu2+ is reported which incorporates poly-l-aspartic acid (PLAsp) with 32–96 aspartate units as a selective ligand for the metal ion. PLAsp is covalently attached to a gold electrode modified with a monolayer of 3-mercaptopropionic acid using carbodiimide coupling via an N-hydroxysuccinimide (NHS) ester intermediate. The acid side groups and deprotonated peptide nitrogens on two aspartate moieties are thought to be primarily responsible for chelation of Cu2+, which remains bound when reduced to Cu+. A consequence of the multiple binding points that are available with a polypeptide is the low detection limit. The lowest concentration detected was 3 nM (0.2 ppb) achieved with Osteryoung square wave voltammetry. This detection limit compares favourably with that of ICP-OES and previously reported cysteine-modified electrodes. Analysis of tap and lake water samples using the PLAsp-modified electrode agreed well with ICP-OES analysis of the same samples.

One-dimensional growth of TiO2 nanorods from ilmenite sands

Growth mechanisms of TiO₂ nanorods synthesized from mineral ilmenite using ball milling and annealing method have been systematically investigated. Two annealing processes are needed to grow the nanorods. The heating rate and gaseous environment in the first annealing step are critical to the formation of intermediate phases; these and the annealing atmosphere in the second heating play very important roles in nanorod growth. One-dimensional growth of the nanorods induced by low-temperature annealing in nitrogen plus hydrogen is possibly driven by atom vacancy diffusion in addition to surface diffusion.

Growth of V2O5 nanorods from ball-milled powders and their performance in cathodes and anodes of lithium-ion batteries

The two-stage procedure of ball milling and annealing in air represents a prospective method of preparing nanorods of V₂O₅ with electrochemical properties suitable for the application in lithium-ion batteries. Commercially purchased V₂O₅ powder is milled in a ball mill as the first step of the synthesis. The as-milled precursor is subsequently annealed in air to produce the morphology of nanorods via solid-state recrystallization. We have recently investigated intermediate stages of the formation of nanorods, and this paper summarizes the synthesis method including the description of the current understanding of the growth mechanism. The obtained V₂O₅ nanorods have been assessed as an electrode material for both anodes and cathodes of lithium-ion batteries. When used in cathodes, the nanorods demonstrate a better retention of capacity upon cycling than that of the commercially available powder of V₂O₅. When used in anodes, the performances of nanorods and the reference V₂O₅ powder are similar to a large extent, which is related to a different operating mechanism of V₂O₅ in anodes. The experimentally observed capacity of V₂O₅ nanorods in an anode has stabilized at the level of about 450 mAh/g after few cycles.