Replicating the cross-sectional distribution of house-dust mite allergen found in carpet

With a view to producing carpets that could be used to determine the ease of particulate aerosolisation during domestic activity, we measured the cross-sectional distribution of dust-mite allergen, Der p 1, produced using American Society for Testing and Materials method (ASTM F608–89) for embedding house dust in carpets with that produced by several alternative protocols. Allergen concentrations produced at different levels within the pile using the different techniques were also compared with those in carpets from actual houses – in which the majority of allergen is typically found towards the base of the pile. To obtain profiles of allergen, horizontal sections, 2-mm thick, were taken from new carpets after they had been seeded with dust and embedded using one of four following techniques: (1) dragging a fixed roller across the surface of the carpet four times, (2) using the same roller but following it up with 200 revolutions in a hexapod wear simulator, (3) dragging the fixed roller across the carpet surface 30 times (the ASTM method), and (4) 2 minutes under a commercial plate compactor. Fibre from each 2-mm-thick section was collected and the Der p 1 content determined using enzyme linked immunosorbent assay and results expressed as ng Der p 1 per area in each section. Embedding with a fixed roller alone was not found to be particularly effective, resulting in roughly equal amounts of dust being apportioned within each pile layer, irrespective of the number of embedding passes used. In contrast, a distribution biased towards the base of the pile was found after roller-embedding/hexapod wear, although still to a lesser extent than has been observed in used carpets. Plate compaction gave a similar allergen distribution profile to combined roller/hexapod treatment but was considerably easier to perform. Thus, both techniques offer promise for researchers seeking to replicate the cross-sectional distribution of dust mite allergen found in carpets after actual use (and conceivably other particulate pollutants also).     

Temporal coordination and adaptation to rate change in music performance.

People often coordinate their actions with sequences that exhibit temporal variability and unfold at multiple periodicities. We compared oscillator- and timekeeper-based accounts of temporal coordination by examining musicians' coordination of rhythmic musical sequences with a metronome that gradually changed rate at the end of a musical phrase (Experiment 1) or at the beginning of a phrase (Experiment 2). The rhythms contained events that occurred at the same periodic rate as the metronome and at half the period. Rate change consisted of a linear increase or decrease in intervals between metronome onsets. Musicians coordinated their performances better with a metronome that decreased than increased in tempo (as predicted by an oscillator model), at both beginnings and ends of musical phrases. Model performance was tested with an oscillator period or timekeeper interval set to the same period as the metronome (1:1 coordination) or half the metronome period (2:1 coordination). Only the oscillator model was able to predict musicians' coordination at both periods. These findings suggest that coordination is based on internal neural oscillations that entrain to external sequences. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A monolithic computational approach to thermo‐structure interaction

In the present work, a monolithic solution approach for thermo‐structure interaction problems motivated by the challenging application of the behaviour of rocket nozzles is proposed. Structural and thermal fields are independently discretised via finite elements. The resulting system of equations is solved via a monolithic thermo‐structure interaction scheme, which is constructed by a block Gauss–Seidel preconditioner in combination with algebraic multigrid methods. The proposed method is tested for four numerical examples, the second Danilovskaya problem, a simplified rocket nozzle configuration, an internally loaded hollow sphere, and a fully three‐dimensional nozzle configuration of a subscale thrust chamber. Good agreement of the numerical results with results from the literature is observed. Furthermore, it is shown that the monolithic solution algorithm can handle the complete range of the parameter spectrum, whereas partitioned algorithms are limited to a certain parameter range only. Moreover, the monolithic algorithm exhibits improved efficiency and robustness compared to partitioned algorithms. Copyright © 2013 John Wiley & Sons, Ltd.     

Thermochemical stability of the Y2O3–SiO2 system

A thermodynamic study was carried out in order to quantify the stability of yttrium silicates under different atmospheres (argon, air, moisture), and to predict their behaviour as an EBC. For this purpose, the partial pressures of gaseous species formed during the reactive vaporization in equilibrium with yttrium silicates were evaluated and compared to those over each oxide taken separately. The partial pressures of silicon and rare earth hydroxides at the equilibrium over rare earth silicates are lower than those over each single oxide. Thus yttrium silicates appear to be sufficiently stable to be promising materials to be used as environmental barrier coatings.     

Effect of itaconic acid on the wet scrub resistance of highly pigmented paints for architectural coatings

This study investigates the influence of carboxylic monomers, such as itaconic acid (IA), on the colloidal properties of the latexes made by semi-continuous emulsion copolymerization of styrene (STy) with n-butyl acrylate (BA). A number of copolymerization runs were carried out with different IA concentrations. The effect of functional monomer on the overall conversion, the colloidal properties of the latexes, and the distribution of the carboxylic groups (buried, particle surface and aqueous phase) were examined. The carboxylic groups present in the latexes were analyzed using conductimetric and potentiometric titrations. The behavior of the IA on the wet scrub resistance of highly pigmented paints for architectural coatings was examined and correlated with the distribution of the carboxylic groups. The results obtained showed that the properties of highly pigmented paints are greatly dependent on the amount and distribution of the carboxylic groups. The carboxylic acid distributed in the aqueous phase has a strong influence on the wet scrub resistance and on the characteristics of the final products.     

Membrane phospholipids and sterols in microfiltered milk fat globules

Native milk fat globules of various mean diameters, ranging from d₄₃ = 2.3 µm to 8.0 µm, were obtained using microfiltration of raw whole milk. After milk fat globule washing, the milk fat globule membrane (MFGM) was separated by manual churning. After total lipid extraction and separation of polar lipids, their phospholipid (PL) and sterol composition was measured using thin‐layer chromatography, methyl ester analyses by gas chromatography, and gas chromatography coupled to mass spectrometry. The main PL species were phosphatidylethanolamine, phosphatidylcholine and sphingomyelin. The respective fatty acid composition of each PL species was measured. Many different minor bioactive sterols were detected in the MFGM, e.g. lanosterol, lathosterol, desmosterol, stigmasterol and β‐sitosterol. No significant differences in the PL and sterol profile were found between MFGM extracted from small and large milk fat globule fractions.     

Octanethiol coating of nano-sized copper powders using the vapor self-assembled monolayer method

Recent research has focused on preventing copper oxidation for direct wiring applications. In this study, a novel coating method was developed for nano-sized copper powders using vapor self-assembled monolayer (VSAM). The surfaces of oxidized and non-oxidized copper powders were studied to determine whether they can be coated with a vapor form of octanethiol. It was found that non-oxidized copper powders were successfully coated with the vapor form of octanethiol according to X-ray photoelectron spectroscopy (XPS) analysis. However, due to the partial coating of self-assembled monolayer (SAM) on a copper surface, a very small amount of copper oxide was detected when the coating mechanism was verified using Atomic Force Microscopy (AFM). Overall, the vapor form of octanethiol successfully adhered to the surface of nanosized copper powders, constituting the novel method of preventing oxidation. A complete coating method for the nano-sized copper powders must be developed in future research.