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Abstract: The scanning tunneling microscopy and temperature programmed oxidation methods were used to study the catalytic oxidation of graphite by mass-selected Ru nanoparticles. Channeling by the nanoparticles was observed on the unsputtered HOPG basal surface at temperatures above 750°C in 10−6 mbar . ion bombardment was used to create layers of disordered carbon of various depths on the HOPG surface. The channel propagation rate in the disordered carbon layer was found to increase for larger nanoparticles. The depth of the interface between the disordered carbon layer and the graphite determined whether the nanoparticles etched paths parallel or perpendicular to the surface. The gasification onset temperature depended on the degree of graphitisation of the surface, with more heavily sputtered surfaces undergoing gasification at much lower temperatures than the unsputtered surface. [ABSTRACT FROM AUTHOR]

Abstract: A method for direct distillation of milk was developed using a high-vacuum distillation unit: solvent-assisted flavour evaporation unit (SAFE unit). Distillation of flavour compounds was carried out at low temperature, reducing the risk of artefact formation during the distillation process. After distillation, volatiles were extracted into dichloromethane and concentrated before separation on a gas chromatograph coupled with mass spectrometer detection (GCMS). Reproducibility of the SAFE method was determined by analysing the volatiles in 6 milk samples from 3 different cartons of milk. For 20 out of 27 volatile compounds, coefficients of variation below 40% were found. The method proved applicable to measure accumulation of volatile oxidation products in raw milk with 25μm copper(II)sulfate added, and stored in the dark for 3 days at 4°C. A simpler solid phase microextraction (SPME) method was used for the same milk, and oxidation products could only be identified after 3 days of storage at 4°C. The SPME method can be used to describe the ongoing oxidation and the oxidative capacity of milk. Because of the high sensitivity of the SAFE method it was possible to identify compounds present in low concentrations, meaning that compounds with low-flavour thresholds and potentially high impact on the flavour may be identified. [Copyright &y& Elsevier]

The variation in susceptibility to light-induced lipid and protein oxidation was studied in relation to the concentration of riboflavin, fatty acid composition, α-, γ-, and δ-tocopherol and β-carotene, lutein and zeaxanthine in milk from cows fed diets with roughage containing either grass silage or corn silage mixed with concentrates. The results show that milk from cows fed grass silage had a higher concentration of the antioxidants measured. The contents of unsaturated C18 fatty acids were significantly different in the two types of milk, showing that the compositions of antioxidants and fatty acids were influenced by the feeding. Despite a higher antioxidative capacity in the milk from cows fed grass silage, lipid oxidation was higher in this milk compared to milk from cows fed corn silage. The results indicate that quenching of singlet oxygen by the antioxidants did not prevent lipid oxidation. The degree of unsaturation in linolenic acid, C18:3, is proposed to be important for the higher accumulation of lipid hydroperoxides in milk from cows fed grass silage. In contrast to milk from cows fed grass silage being more vulnerable to lipid oxidation, milk from cows fed corn silage is more vulnerable to protein oxidation. The results indicate that protein oxidation occurs independently of lipid oxidation. It is concluded that the higher concentration of antioxidants in milk from cows fed grass silage is able to extend the lag phase of protein oxidation and delay the formation of dityrosine. [Copyright &y& Elsevier]