Controlled Growth of Highly Aligned Cu Nanowires by Pulse Electrodeposition in Nanoporous Alumina.

Metallic nanowire networks are emerging as potential replacements for transparent conducting oxide coatings because of their high conductivity, flexibility and relative transparency. However, a cheap, reliable and controlled manufacturing process is required to exploit this and the surface of the copper nanowire needs to be protected if high conductivity is to be retained. In this study a fabrication method for highly aligned and densely packed copper nanowires with controlled length using pulse-electrodeposition and a nanoporous alumina template has been developed. Nanoporous alumina was obtained by anodisation of pure aluminum in oxalic acid using a two-step anodisation process. In order to provide the conductivity at the bottom of the pores, a dendritic structure at the interface was created through the stepwise voltage reduction method with a voltage reduction rate of 15 V/s followed by mild chemical etching. Highly repeatable near 100% filling of copper is achieved. Copper nanowire length was highly controllable from 100 nm to 2 µm with a fixed diameter of 60 ± 5 nm by monitoring current density during the deposition. Such controlled growth of Cu nanowires could lead towards transparent conducting layer applications but the protection of the material against oxidation remains an issue.

Tunable High Refractive Index Polymer Hybrid and Polymer-Inorganic Nanocomposite Coatings.

Atomized spray plasma deposition (ASPD) provides a single-step, low-temperature, and dry approach for the preparation of high refractive index hybrid polymer or polymer-inorganic nanocomposite coatings. Refractive indices as high as 1.936 at 635 nm wavelength have been obtained for ASPD 4-bromostyrene/toluene-TiO2 nanocomposite layers containing low titania loadings. Thin films with any desired refractive index up to 1.936 can be easily deposited onto a variety of substrates by varying the precursor mixture composition. ASPD overcomes disadvantages commonly associated with alternative fabrication methods for depositing high refractive index coatings (elevated temperatures, wet processes, UV curing steps, and much greater inorganic loadings).

High yield synthesis of graphene quantum dots from biomass waste as a highly selective probe for Fe3+ sensing.

Graphene quantum dots (GQDs), a novel type of zero-dimensional fluorescent materials, have gained considerable attention owing to their unique optical properties, size and quantum confinement. However, their high cost and low yield remain open challenges for practical applications. In this work, a low cost, green and renewable biomass resource is utilised for the high yield synthesis of GQDs via microwave treatment. The synthesis approach involves oxidative cutting of short range ordered carbon derived from pyrolysis of biomass waste. The GQDs are successfully synthesised with a high yield of over 84%, the highest value reported to date for biomass derived GQDs. As prepared GQDs are highly hydrophilic and exhibit unique excitation independent photoluminescence emission, attributed to their single-emission fluorescence centre. As prepared GQDs are further modified by simple hydrothermal treatment and exhibit pronounced optical properties with a high quantum yield of 0.23. These modified GQDs are used for the highly selective and sensitive sensing of ferric ions (Fe3+). A sensitive sensor is prepared for the selective detection of Fe3+ ions with a detection limit of as low as 2.5 × 10-6 M. The utilisation of renewable resource along with facile microwave treatment paves the way to sustainable, high yield and cost-effective synthesis of GQDs for practical applications.

How cell culture conditions affect the microstructure and nanomechanical properties of extracellular matrix formed by immortalized human mesenchymal stem cells: An experimental and modelling study.

This paper presents an investigation of how different culture media (i.e. basal and osteogenic media) affect the nanomechanical properties and microstructure of the mineralized matrix produced by the human mesenchymal stem cell line Y201, from both an experimental and theoretical approach. A bone nodule (i.e. mineralized matrix) cultured from basal medium shows a more anisotropic microstructure compared to its counterpart cultured from an osteogenic medium. As confirmed by finite element simulations, this anisotropic microstructure explains the bimodal distribution of the corresponding mechanical properties very well. The overall nanomechanical response of the bone nodule from the osteogenic medium is poorer compared to its counterpart from the basal medium. The bone nodules, from both basal and osteogenic media, have shown reverse aging effects in terms of mechanical properties. These are possibly due to the fact that cell proliferation outcompetes the mineralization process.