Enhanced catalytic activity of Ni on η-Al2O3 and ZSM-5 on addition of ceria zirconia for the partial oxidation of methane

peer-reviewedNickel supported on η-Al2O3 and ZSM-5(80) catalysts with and without the addition of ceria-zirconia, were prepared by co-precipitation and wet impregnation methods and used for the low temperature catalytic partial oxidation of methane (CPOM). The catalysts were tested under reaction temperatures of between 400 and 700 °C with a WHSV of 63,000 mL g−1 h−1. The activity of the catalyst was found to be dependent on the support and preparation method. The optimum catalyst composition of those tested was 10% Ni on 25%CeO2-ZrO2/ZSM-5(80), prepared by co-precipitation, where the reaction reached equilibrium conversion at 400 °C (T50% < 400 °C), which is one of the lowest temperatures reported to date. Further increases in temperature led to improved selectivity to CO reaching 60% at 600 °C. Although the observed kinetics were found to be controlled by strong adsorption of CO at lower temperature, this was an equilibrium limitation with longer time on stream experiments showing no decrease in the catalyst activity over 25 h at 400 °CACCEPTEDpeer-reviewe

Investigating the Solubility and Cytocompatibility of CaO-Na2O-SiO2/TiO2 Bioactive Glasses

This study aims to investigate the solubility of a series of titanium (TiO2)-containing bioactive glasses and their subsequent effect on cell viability. Five glasses were synthesized in the composition range SiO2-Na2O-CaO with 5 mol % of increments TiO2 substituted for SiO2. Glass solubility was investigated with respect to (1) exposed surface area, (2) particle size, (3) incubation time, and (4) compositional effects. Ion release profiles showed that sodium (Na+) presented high release rates after 1 day and were unchanged between 7 and 14 days. Calcium (Ca2+) release presented a significant change at each time period and was also composition dependent, where a reduction in Ca2+ release is observed with an increase in TiO2 concentration. Silica (Si4+) release did not present any clear trends while no titanium (Ti4+) was released. Cell numbers were found to increase up to 44%, compared to the growing control population, with a reduction in particle size and with the inclusion of TiO2 in the glass composition

Influence of particle size on the physicochemical properties and stickiness of dairy powders

peer-reviewedThe compositional and physicochemical properties of different whey permeate (WPP), demineralised whey (DWP) and skim milk powder (SMP) size fractions were investigated. Bulk composition of WPP and DWP was significantly (P < 0.05) influenced by powder particle size; smaller particles had higher protein and lower lactose contents. Microscopic observations showed that WPP and DWP contained both larger lactose crystals and smaller amorphous particles. Bulk composition of SMP did not vary with particle size. Surface composition of the smallest SMP fraction (<75 μm) showed significantly lower protein (−9%) and higher fat (+5%) coverage compared with non-fractionated powders. For all powders, smaller particles were more susceptible to sticking. Hygroscopicity of SMP was not affected by particle size; hygroscopicity of semi-crystalline powders was inversely related to particle size. This study provides insights into differences between size fractions of dairy powders, which can potentially impact the sticking/caking behaviour of fine particles during processing.ACCEPTEDpeer-reviewe

Layer-by-Layer Growth and Photocurrent Generation in Metal–Organic Coordination Films

A series of metal–organic coordination films with tetra­(4-carboxyphenyl)­porphyrin (TCPP) and trimesic acid (TMA) ligands and Cu²⁺ ion linkers were grown layer-by-layer on TiO₂-modified indium tin oxide electrodes and the cathodic short-circuit photocurrent that they generate was studied. The layer-by-layer growth was verified by using absorption spectroscopy in the visible and X-ray photoelectron spectroscopy, highlighting the consistent coverage of TCPP in each layer. The photocurrent increases nonlinearly with the number of TCPP layers and with the number of TMA layers introduced as a buffer between TCPP and substrate. These observations are rationalized by considering substrate screening of the TCPP photoexcited state and charge transport across the metal–organic multilayers

Development of high power laser ablation process for polycrystalline diamond polishing - Part 1: Fundamental understanding of PCD ultra-short pulsed laser ablation

Diamond exhibits incredible chemical and mechanical properties Utilization of diamond for industrial applications has universally spread thanks to the discovery of its industrial synthesis and the enhancement of its properties by its formation under a polycrystalline form, named polycrystalline diamond composite (PCD). For industrial production PCD bulk material has to pass through several complex processes from leaving the belt press down to be polished as a wafer with a mirror-finished surface. Especially the polishing process is an extremely laborious method originally discovered to polish diamond gemstones hundred years ago'. Laser ablation has repeatedly been proven to be a cost efficient process for industrial purposes. Elaboration of new ablation processes for PCD manufacturing is increasing supported by the continuous improvement of ultra-short lasers and their high performances'. The ambition of this project is to develop an alternative polishing process of PCD wafers by ultra-short laser ablation achieving better performances than traditional mechanical polishing. This paper presents a relationship between material related properties of various PCD grades and performance of ultra-short laser ablation process at low laser average power. Specifically, this paper demonstrates the high impact of the pulse duration on the ablation rate, the dependence of the optimal fluence for highest ablation rate on the PCD composition and the effect of fluence on diamond graphitization through Raman spectroscopy analysis

Titania-silver and alumina-silver composite nanoparticles: novel, versatile synthesis, reaction mechanism and potential antimicrobial application

Titania–silver (TiO2–Ag) and alumina–silver (Al2O3–Ag) composite nanoparticles were synthesised by a simple, reproducible, wet chemical method under ambient conditions. The surface of the oxides was modified with oleic acid, which acted as an intermediate between the oxide surface and the silver nanoparticles. The resulting composite nanoparticles were thoroughly characterized by XRD, TEM, XPS, FTIR and TGA to elucidate the mode of assembly of Ag nanoparticles on the oxide surfaces. Epoxy nanocomposites were formulated with TiO2–Ag and Al2O3–Ag to examine potential applications for the composite nanoparticles. Preliminary results from disk diffusion assays against Escherichia coli DH5α and Staphylococcus epidermidis NCIMB 12721 suggest that these TiO2–Ag and Al2O3–Ag composite nanoparticles have potential as antimicrobial materials

Colloidal synthesis of wurtzite Cu2ZnSnS4 nanorods and their perpendicular assembly

The quaternary copper chalcogenide, Cu2ZnSnS4, is an important emerging material for the development of low cost and sustainable solar cells. Here we report a facile solution synthesis of stoichiometric Cu2ZnSnS4 in size controlled nano-rod form (11 ×35 nm). The monodisperse nanorods have a band gap of 1.43 eV and can be assembled into perpendicularly aligned arrays by controlled evaporation from solution