Chemical bath deposition of cadmium sulphide on silicon nitride: Influence of surface treatment on film growth

Nanoparticulate cadmium sulphide was grown by a chemical bath method on PECVD silicon nitride with various surface treatments. It was found that the packing density of the film increased in the order: untreated surface < mercaptopropyl-derivatised surface < ultra-thin (discontinuous) gold- or platinum-treated surface. This behaviour was rationalised by assuming that surface concentrations of Cd²⁺ or S²⁻ could be increased over the bulk values by producing a surface with ‘soft base’ or ‘soft acid’ chemistry, respectively.Nanoparticle diameters were larger with ultra-thin platinum treatment than with gold. These observations may allow ordered arrays of cadmium sulphide nanoparticles to be prepared by a masking - gold seeding - bath deposition procedure.     

Family stress and parental responses to children’s negative emotions: Tests of the spillover, crossover, and compensatory hypotheses.

The relations between 4 sources of family stress (marital dissatisfaction, home chaos, parental depressive symptoms, and job role dissatisfaction) and the emotion socialization practice of mothers’ and fathers’ responses to children’s negative emotions were examined. Participants included 101 couples with 7-year-old children. Dyadic analyses were conducted using the Actor–Partner Interdependence Model and relations were tested in terms of the spillover, crossover, and compensatory hypotheses. Results suggest that measures of family stress relate to supportive and nonsupportive parental responses, though many of these relations differ by parent gender. The results are discussed in terms of the 3 theoretical hypotheses, all of which are supported to some degree depending on the family stressor examined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of domestic processing on the content and bioaccessibility of carotenoids from chili peppers (Capsicum species)

The content and bioaccessibility of carotenoids from different chili peppers were analysed and the effects of typical domestic processing were investigated. Peppers were analysed before and after cooking by conventional boiling (10 min in 100 °C water) and also following a freezing period of four months in a domestic freezer (−20 °C). The content and bioaccessibility of the eight carotenoids quantified varied, depending on cultivar, species, colour and processing. Provitamin A carotenoids (β-carotene and β-cryptoxanthin) and capsanthin were present at highest concentrations in the samples before and after processing. In general, yellow and orange peppers were the best sources of lutein, zeaxanthin and neoxanthin. Xanthophyll carotenoids were more efficiently transferred to the micelles and, therefore, were also more bioavailable. Processing decreased the carotenoid content in certain samples; however, the micellar content was generally not lower for processed peppers; therefore the bioaccessibility of carotenoids from processed peppers is enhanced relative to unprocessed peppers.     

Stimulation of osteoblasts using rest periods during bioreactor culture on collagen-glycosaminoglycan scaffolds

Osteoblasts respond to mechanical signals which play a key role in the formation of bone however, after extended periods of stimulation they become desensitised. Mechanosensitivity has been shown to be restored by the introduction of resting periods between loadings. The aim of this study was to analyse the effect of rest periods on the response of osteoblast-like cells seeded on collagen-glycosaminoglycan (CG) scaffolds in a flow perfusion bioreactor up to 14 days. Short (10 s) and long (7 h) term rests were incorporated into stimulation patterns. Constructs cultured in the bioreactor had a more homogenous cell distribution albeit with lower cell numbers than the static group. Osteopontin expression was significantly higher on the rest-inserted group than on the steady flow and static control. These results indicate that the insertion of short term rests during flow improves cellular distribution and osteogenic responses on CG constructs cultured in a flow perfusion bioreactor.     

Similarity and generalized analysis of efficiencies of thermal energy storage systems

This paper examined the features of three typical thermal storage systems including: 1) direct storage of heat transfer fluid in containers, 2) storage of thermal energy in a packed bed of solid filler material, with energy being carried in/out by a flowing heat transfer fluid which directly contacts the packed bed, and 3) a system in which heat transfer fluid flows through tubes that are imbedded into a thermal storage material which may be solid, liquid, or a mixture of the two. The similarity of the three types of thermal storage systems was discussed, and generalized energy storage governing equations were introduced in both dimensional and dimensionless forms. The temperatures of the heat transfer fluid during energy charge and discharge processes and the overall energy storage efficiencies were studied through solution of the energy storage governing equations. Finally, provided in the paper are a series of generalized charts bearing curves for energy storage effectiveness against four dimensionless parameters grouped up from many of the thermal storage system properties including dimensions, fluid and thermal storage material properties, as well as the operational conditions including mass flow rate of the fluid, and the ratio of energy charge and discharge time periods. Engineers can conveniently look up the charts to design and calibrate the size of thermal storage tanks and operational conditions without doing complicated individual modeling and computations. It is expected that the charts will serve as standard tools for thermal storage system design and calibration.     

Impact of oxygen adsorption on a population of mass produced carbon nanotube field effect transistors

A large population of carbon nanotube field effect transistors (CNT-FETs), including a variety of channel morphologies with single and multiple tubes, was electrically characterized in atmospheric, ultra-high vacuum (UHV) and oxygen-rich environments. Devices were systematically classified according to the number and nature of the bridging CNTs based on a rigorous device characterization methodology. A statistical analysis of the interaction of oxygen with such a complex population of devices reveals shifts in carrier type, contact resistance and threshold voltages indicative of both charge trapping and transport barrier modulation at the tube-electrode interface. Devices with a single semiconducting tube could be changed from p-type (hole conduction) at atmosphere to n-type (electron conduction) through vacuum-annealing. Furthermore, the average resistance of these CNT-FETs after annealing was observed to decrease from 2.16 MΩ under UHV to 1.0 MΩ in the presence of pure oxygen while threshold voltages shifted from −5.5 V to −2.2 V. Overall responses to ambient conditions is dependent on the device morphology as well as the use of thermal annealing.     

On rimming flows with shocks

We examine rimming flows, i.e. flows of a liquid film on the inside of a horizontal rotating cylinder. So far this problem has mostly been explored using the so-called lubrication approximation (LA). It was shown that, if the volume of the liquid in the cylinder exceeds a certain threshold, then a shock similar to a tidal bore appears in the lower half of the cylinder on its rising side. The position of the shock can be characterized by the polar angle θ _s, with a value between θ _s = −90° (the bottom of the cylinder) and θ _s = 0° (the horizontal direction). In this study, we examine rimming flows without the LA, by solving numerically the exact Stokes equations. It is shown that a steady solution describing a (smoothed) shock exists only if -60^° <~q_s < 0 ^°{-60^{\circ}\lesssim\theta_{\rm s} <0 ^{\circ}} . Shocks with lower locations overturn, so no steady solution exists. It is also shown that smoothed-shock solutions have an oscillating structure upstream from the shock. If, however, capillary effects are taken into account, the range of θ _s where solutions overturn contracts, and if surface tension is sufficiently strong, solutions exist for all values of θ _s.     

A review of quantitative microbial risk assessment in the management of Escherichia coli O157:H7 on beef

Since Escherichia coli O157:H7 first emerged as a food borne pathogen in the mid 1980s, it has been linked to many cases of food poisoning across the world. While multiple sources and routes of transmission for this pathogen are now recognised, beef and beef products remain an important vehicle of the pathogen and continue to be linked to outbreaks across the developed world. Much research has been directed at E. coli O157:H7 transmission, survival and control in the beef chain and this paper presents an overview of current knowledge on this pathogen in the beef chain from primary production through slaughter, processing, distribution, final preparation and cooking. In order to strategically manage E. coli O157:H7 and to devise approaches to reduce the public health risk posed, many national and international groups have applied quantitative risk assessment techniques to model the risk posed by E. coli O157:H7 in beef, particularly in ground/minced beef which is most often linked with infection. This paper reviews these quantitative risk assessments and their application in managing the risk posed by E. coli O157:H7 in beef.     

Bioactivity of ellagic acid-, lutein- or sesamol-enriched meat patties assessed using an in vitro digestion and Caco-2 cell model system

Interest exists in the manufacture of functional meat products whereby synthetic antioxidants are replaced with naturally-sourced compounds. Therefore the aim of this study was to determine the bioactivity of pork and beef patties containing ellagic acid (600 μg/g), lutein (200 μg/g) or sesamol (500 μg/g). Cooked pork and beef patties were subjected to an in vitro digestion procedure and the resultant micelles were added to human intestinal Caco-2 cells. Supplementation with micelles from lutein-enriched pork patties protected (P < 0.05) against H₂O₂-induced cell injury whereas the presence of control beef, lutein-enriched beef or ellagic acid-enriched beef, at levels ?20% (v/v), enhanced (P < 0.05) oxidant-induced cytotoxicity. None of the pork patties significantly modulated cellular glutathione content. Micelles from all the enriched pork patties significantly protected against H₂O₂-induced DNA damage. In conclusion, the cytoprotective and genoprotective effects of ellagic acid, lutein, and sesamol, when incorporated into meat systems, depend greatly on the food matrix.