Search

Abstract: The present paper develops and validates a 3D model for the simulation of glass tempering. It is assembled from well-known models of temperature dependent viscoelasticity and structural relaxation and predicts both transient and steady-state stresses in complex 3D glass geometries. The theory and implementation of the model is comprehensively given and the model is carefully checked and validated. It is demonstrated that by adjusting a single parameter in the model, experimental results can be replicated accurately even for cooling rates far from normal. [Copyright &y& Elsevier]

Abstract: Supported molybdenum-sulfide nanoparticles are known catalysts for petroleum hydrodesulfurization as well as for electrochemical hydrogen evolution. In this study, we investigate molybdenum-sulfide nanoparticles supported on Au(111) using X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM), aiming to correlate spectroscopically determined chemical states with atomically resolved nanostructure. The results of this study allow us to conclude the following: (1) the XPS results from our model system are in good agreement with previously published results on supported MoS2 for industrial applications, validating in part the fidelity of the model system; (2) STM reveals that catalytically active, crystalline MoS2 nanoparticles exhibiting the well-known metallic edge state are only present after a post-deposition annealing step in the synthesis procedure, without which the particles exhibit amorphous shapes and incomplete sulfidation; and (3) the sulfided nanoparticles are found to be stable in air at room temperature. [Copyright &y& Elsevier]

Abstract: As aged individuals are frequently exposed to short-term disuse caused by disease or musculoskeletal injury, it is important to understand how short-term disuse and subsequent retraining affect lower limb mechanical muscle function. The purpose of the present study was, therefore, to investigate the effect of 4days of lower limb disuse followed by 7days of active recovery on mechanical muscle function of the knee extensors in young (24.3±0.9years, n =11) and old (67.2±1.0years, n =11) recreationally active healthy males. Slow and moderate dynamic muscle strength were assessed using isokinetic dynamometry (60 and 180°s−1, respectively) along with isometric muscle strength and rapid muscle force capacity examined as contractile rate of force development (RFD), Impulse, and relative RFD (rRFD) during the initial phase of contraction (100ms time interval relative to onset of contraction). Prior to disuse, marked age-related differences (p<0.05) were observed in isometric and dynamic muscle strength (~35%) as well as in RFD and Impulse (~39%). Following disuse, young and old individuals experienced comparable decrements (p<0.05) in isometric strength (~9%), slow dynamic strength (~13%), and RFD and Impulse (~19%), whereas old individuals only experienced decrements (p<0.05) in moderate dynamic strength (12%) and rRFD (~17%). Following recovery, all measures of mechanical muscle function were restored in young individuals compared to pre-disuse values, while isometric, slow and moderate dynamic muscle strength remained suppressed (p<0.05) in old individuals (~8%) along with a tendency to suppressed RFD100 (p=0.068). In conclusion, 4days of lower limb disuse led to marked decrements in knee extensor mechanical muscle function in both young and old individuals, yet with greater decrements observed in moderate dynamic strength and rapid muscle force capacity in old individuals. While 7days of recovery – including free ambulation, one test session and a single session of strength training – was sufficient to restore mechanical muscle function in young individuals, old individuals appeared to have an impaired ability to fully recover as evidenced by suppressed values of isometric and dynamic muscle strength and rapid muscle force capacity. [Copyright &y& Elsevier]

Three groups of Holstein cows were fed concentrates with different fatty acid compositions; one high in saturated lipids, another high in unsaturated lipids and the last one simulating high de novo synthesis. The feedings resulted in milk with fat contents of 5.0%, 3.7% and 4.0%, respectively. The milk fat globules (MFGs) were significantly larger in the milk with the highest fat content. All three types of milk were pumped for 450 s at various shear rates and temperatures. Afterwards, measurement of particle size distribution showed that the highest coalescence of MFGs in the milk occurred with the largest fat globules. Moreover, the fat globules were more unstable at a pumping temperature of 31°C compared with lower temperatures. Likewise, an increase was found in free fatty acids for milk with the largest MFGs, indicating that milk with a high fat content is more unstable when exposed to mechanical stress. Xanthine oxidase activity in raw milk was not affected by pumping. The results are discussed in relation to automatic milking systems. [Copyright &y& Elsevier]

Pork muscle samples (M. longissimus dorsi and M. psoas major) were obtained from pigs given one of four dietary treatments, (1) control diet, (2) supplemental iron (7g iron (II) sulphate/kg feed), (3) supplemental vitamin E (200 mg dl-α-tocopheryl acetate/kg of feed) and (4) supplemental vitamin E+supplemental iron. Vitamin C was supplemented to all dietary treatments to facilitate iron uptake. Vitamin E and iron tissue levels were determined for each treatment. Warmed-over flavour (WOF) was evaluated by a trained sensory panel (n=8) for the four treatments which were cooked and refrigerated at 4 °C for up to 5 days. Thawing loss, driploss and thiobarbituric acid reactive substances (TBARS) were also determined. Vitamin E muscle tissue levels were greatest in the Iron/vitamin E-treated group followed by the vitamin E group, control and iron treated groups, respectively for M. longissimus dorsi. Whereas, for M. psoas major vitamin E tissue levels were in order of magnitude, vitamin E>iron/vitamin E>iron>control group. Iron tissue levels were in the order vitamin E>iron/vitamin E>control>iron for M. longissimus dorsi and iron>vitamin E>control>iron/vitamin E for M. psoas major. Thus, vitamin E and vitamin C promoted non-supplemental iron absorption in the vitamin E-treated group for M. longissimus dorsi and to a lesser extent for M. psoas major. M. psoas major was more susceptible to warmed-over flavour development than M. longissimus dorsi for all treatments as determined by sensory profiling, due to higher tissue iron levels. From sensory profiling, WOF development in M. longissimus dorsi and M. psoas major was highest in the iron-supplemented groups followed by the control and vitamin E-supplemented groups. [Copyright &y& Elsevier]

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: Scanning tunneling microscopy was used to compare the morphologies of Ru nanoparticles deposited onto highly-oriented graphite surfaces using two different physical vapour deposition methods; (1) pre-formed mass-selected Ru nanoparticles with diameters between 2nm and 15nm were soft-landed onto HOPG surfaces using a gas-aggregation source and (2) nanoparticles were formed by e-beam evaporation of Ru films onto HOPG. The particles generated by the gas-aggregation source are round in shape with evidence of facets resolved on the larger particles. Annealing these nanoparticles when they are supported on unsputtered HOPG resulted in the sintering of smaller nanoparticles, while larger particles remained immobile. Nanoparticles deposited onto sputtered HOPG surfaces were found to be stable against sintering when annealed. The size and shape of nanoparticles deposited by e-beam evaporation depend to a large extent on the state of the graphite support and the temperature. Ru deposition onto unsputtered HOPG is characterised by bimodal growth with large flat particles formed on the substrate terraces and smaller diameter particles aligned along the substrate steps. Evaporation onto sputtered HOPG results in the formation of 2nm round particles with a narrow size distribution. Finally, thermal deposition onto both sputtered and unsputtered HOPG at 660°C results in larger particles showing a flat Ru(0001) top facet. [Copyright &y& Elsevier]

The dissociation of CO serves both as a model test reaction on single crystals and as a relevant reaction step for industrial methanation. We combined extensive density functional theory calculations, ultra-high vacuum experiments on well-defined single crystals, and catalytic activity measurements on supported catalysts in a study of the dissociation mechanism of CO on Ni surfaces. We found that this process is highly structure-sensitive and also is sensitive to the presence of hydrogen: Under ultra-high vacuum, with no hydrogen present, the dissociation proceeds through a direct route in which only undercoordinated sites (e.g., steps) are active. Under methanation conditions, the dissociation also proceeds most favorably over undercoordinated sites, but through a COH species. [Copyright &y& Elsevier]

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]