Examination of styrene-divinylbenzene ion-exchange resins, used in contact with food, for potential migrants

The nature of extractable substances from five types of styrene-divinylbenzene ion-exchange resins used in the preparation of foodstuffs was investigated. Strong acid cation resins, strong and weak base anion resins, and an active carbon replacement resin were examined. These resins are used for a variety of purposes including water softening, decalcification of sugar syrups, demineralization, removal of nitrate ions from water and decolourization. Analysis was carried out using electrospray LC-MS- and GC-MS-based methodologies. Extractable substances from new resins were identified as mainly being by-products of the resin manufacturing process. Levels of extractable substances decreased with washing.     

Examining students' retrospective memories of strategy development.

Two studies were conducted to assess students' self-reported use of cognitive study strategies. Both studies used a written survey to assess where and when students were introduced to their preferred study strategies. The 1st study compared high school and university students. The 2nd study compared university students' recollections of strategy use in high school with their present study behaviors. Results from the 2 studies were consistent. All groups, at all times in their education, regardless of course difficulty, preferred repetition strategies. Students were aware of other more sophisticated strategies but used them to a lesser extent. What was most compelling was students' indication that strategy instruction was a late addition to their educational experience, with many indicating high school as their 1st encounter with strategy instruction. These reports suggest that students' dependence on repetition strategies may be a product of the lack of familiarity and flexibility in the execution of more sophisticated strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stability and change in adolescent spirituality/religiosity: A person-centered approach.

Although there has been a substantial increase over the past decade in studies that have examined the psychosocial correlates of spirituality/religiosity in adolescence, very little is known about spirituality/religiosity as a domain of development in its own right. To address this limitation, the authors identified configurations of multiple dimensions of spirituality/religiosity across 2 time points with an empirical classification procedure (cluster analysis) and assessed development in these configurations at the sample and individual level. Participants included 756 predominately Canadian-born adolescents (53% female, 47% male) from southern Ontario, Canada, who completed a survey in Grade 11 (M age = 16.41 years) and Grade 12 (M age = 17.36 years). Measures included religious activity involvement, enjoyment of religious activities, the Spiritual Transcendence Index, wondering about spiritual issues, frequency of prayer, and frequency of meditation. Sample-level development (structural stability and change) was assessed by examining whether the structural configurations of the clusters were consistent over time. Individual-level development was assessed by examining intraindividual stability and change in cluster membership over time. Results revealed that a five cluster-solution was optimal at both grades. Clusters were identified as aspiritual/irreligious, disconnected wonderers, high institutional and personal, primarily personal, and meditators. With the exception of the high institutional and personal cluster, the cluster structures were stable over time. There also was significant intraindividual stability in all clusters over time; however, a significant proportion of individuals classified as high institutional and personal in Grade 11 moved into the primarily personal cluster in Grade 12. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

CFD computations of liquid hydrogen releases

Hydrogen is widely recognized as an attractive energy carrier due to its low-level air pollution and its high mass-related energy density. However, its wide flammability range and high burning velocity present a potentially significant hazard. A significant fraction of hydrogen is stored and transported as a cryogenic liquid (liquid hydrogen, or LH₂) as it requires much less volume compared to gaseous hydrogen. In order to exist as a liquid, H₂ must be cooled to a very low temperature, 20.28 K. LH₂ is a common liquid fuel for rocket applications. It can also be used as the fuel storage in an internal combustion engine or fuel cell for transport applications. Models for handling liquid releases, both two-phase flashing jets and pool spills, have been developed in the CFD-model FLACS. The very low normal boiling point of hydrogen (20 K) leads to particular challenges as this is significantly lower than the boiling points of oxygen (90 K) and nitrogen (77 K). Therefore, a release of LH₂ in the atmosphere may induce partial condensation or even freezing of the oxygen and nitrogen present in the air. A pool model within the CFD software FLACS is used to compute the spreading and vaporization of the liquid hydrogen depositing on the ground where the partial condensation or freezing of the oxygen and nitrogen is also taken into account. In our computations of two-phase jets the dispersed and continuous phases are assumed to be in thermodynamic and kinematic equilibrium. Simulations with the new models are compared against selected experiments performed at the Health and Safety Laboratory (HSL).     

Re‐establishing the paradigm for evaluating halide salt compatibility to study commercial chloride salts at 600°C–800°C

Chloride salts are one candidate for a >700°C concentrating solar power (CSP) cycle, however, many reports from the literature suggest very high reaction rates between chloride salts and structural alloys. Historically, a specific methodology was established for evaluating halide salt compatibility based on solution kinetics. This study returned to that paradigm where the salts are purified and evaluated in sealed capsules before moving to a flowing experiment to determine a true corrosion rate in a temperature gradient for a commercial K–Mg–Na chloride salt. Isothermal testing focused on Ni‐based alloys 230 and 600 at 600°C–800°C. The results indicated there were promising combinations of salt chemistry, temperature, and alloy composition that reduce the extent of reaction. The results of the first monometallic thermal convection loop of alloy 600 run for 1,000 hr with a peak temperature of 700°C showed low attack with rates ≤9 µm/yr.     

Design and processing of porous materials for electronic applications

The use of porosity, either unintentionally or intentionally, in the fabrication of materials for electronic and optoelectronic applications is introduced. Unintentional uses include the fabrication of ceramic magnets, where high electrical resistivities are required to reduce eddy currents at high frequency, and the powder technology, often used, inevitably results in porosity. The generation of light from porous silicon created a huge impact in the early 1990s, followed by extensive work on the mechanism responsible, and has now been followed by a more balanced evaluation of its potential. Porous ferroelectrics have shown significant advantages over dense materials for positive temperature coefficient of resistance applications, and for sensors such as hydrophones, and these will be discussed. Low dielectric constant materials are required for the next generation of silicon integrated circuits, where a reduction compared with silicon dioxide is required, and here porosity is a convenient strategy. Finally, the use of deliberately engineered porous nanostructures, with dimensions in the range of the wavelength of light, are discussed for applications in optical processing.     

Effects of congestion and confining walls on turbulent deflagrations in a hydrogen storage facility-part 1: Experimental study

If the general public is to use hydrogen as a vehicle fuel, customers must be able to handle hydrogen with the same degree of confidence, and with comparable risk, as conventional liquid and gaseous fuels. Since hydrogen is stored and used as a high-pressure gas, a jet release in a confined or congested area can create an explosion hazard. Therefore, hazards associated with jet releases from leaks in a vehicle-refuelling environment must be considered. As there was insufficient knowledge of the explosion hazards, a study was initiated to gain a better understanding of the potential explosion hazard consequences associated with high-pressure leaks from hydrogen vehicle refuelling systems. Our first paper [1] describes the release and subsequent ignition of a high-pressure hydrogen jet in a simulated dispensing area of a hydrogen vehicle refuelling station. In the present paper, an array of dummy storage cylinders with confining walls (to represent isolation from the forecourt area) was used to represent high-pressure hydrogen cylinder storage congestion. Experiments with ignition of premixed 5.4 m × 6.0 m × 2.5 m hydrogen-air clouds and hydrogen jet releases up to 40 MPa pressures were performed. The results are presented and discussed in relation to the conditions giving the highest overpressures. We concluded from the study that the ignition of a jet release gives much higher local overpressure than in the case of ignition of a homogeneous mixture inside the cylinder storage congestion area. The modelling of these results will be presented in Part 2 of this paper.     

The effect of plastic bending on the electrical properties of indium antimonide

Uniform arrays of In- and Sb-dislocations have been introduced into indium antimonide single crystals by high temperature four-point bending, and the densities of the two types of dislocation estimated by the selective etchants calibrated previously. Hall coefficient and electrical conductivity measurements on bent samples confirm preliminary results that both dislocation types act as acceptor centres in n-type material, and interpretations of the temperature-dependence of the electrical properties on the Read and Broudy models have enabled estimation of the dislocation acceptor levels. A new method of analysing experimental data in terms of the Broudy model has been developed, and the model itself modified for the case where the dislocations are in highly polygonised arrays. The different analyses result in widely different dislocation energy levels. From a comparison of these present results with recent studies of dislocations in p-type material it is concluded that the unmodified Read model is most appropriate and that the In-dislocation level lies near the centre of the band gap while the Sb-level lies near the valence band.