Effect of susceptibility to interfacial fracture on fatigue properties of spot-welded high strength sheet steel

While advanced high strength steels (AHSS) have numerous advantages for the automotive industry, they can be susceptible to interfacial fracture when spot-welded. In this study, the susceptibility of interfacial fracture to spot-weld microstructure and hardness is examined, as well as the corresponding relationships between fatigue, overload performance, and interfacial fracture for a TRIP (transformation induced plasticity) steel. Simple post-weld heat-treatments were used to alter the weld microstructure. The effect on interfacial fracture of diluting the weld pool by welding the TRIP material to non-TRIP steel was examined, along with the effect of altering the base material microstructure. Results show that weld hardness is not a good indicator of either the susceptibility to interfacial fracture, or the strength of the joint, and that interfacial fracture does not necessarily lead to a decrease in strength compared to conventional weld-failure mechanisms, i.e. button pullout. It was also found that while interfacial fracture does affect low cycle to failure behavior, there was no effect on high cycle fatigue.

Effect of particle size on the photocatalytic activity of nanoparticulate zinc oxide

In this study, a three-stage process consisting of mechanical milling, heat treatment, and washing has been used to manufacture nanoparticulate ZnO powders with a controlled particle size and minimal agglomeration. By varying the temperature of the post-milling heat treatment, it was possible to control the average particle size over the range of 28–57 nm. The photocatalytic activity of these powders was characterized by measuring the hydroxyl radical concentration as a function of irradiation time using the spin-trapping technique with electron paramagnetic resonance spectroscopy. It was found that there exists an optimum particle size of approximately 33 nm for which the photocatalytic activity is maximized. The existence of this optimal particle size is attributable to an increase in the charge carrier recombination rate, which counteracts the increased activity arising from the higher specific surface area for a sufficiently small particle size.

Mechanochemical synthesis of nanocrystalline SnO2-ZnO photocatalysts

Mechanochemical processing of anhydrous chloride precursors with Na₂CO₃ has been investigated as a means of manufacturing nanocrystalline SnO₂ doped ZnO photocatalysts. High-energy milling and heat-treatment of a 0.1SnCl₂+0.9ZnCl₂+Na₂CO₃+4NaCl reactant mixture was found to result in the formation of a composite powder consisting of oxide grains embedded within a matrix of NaCl. Subsequent washing with deionized water resulted in removal of the NaCl matrix phase and partial hydration of the oxide reaction product with the consequent formation of ZnSn(OH)₆. The extent of this hydration reaction was found to decrease in a linear fashion with the temperature of the post-milling heat-treatment over the range of 400–700 °C. For a heat-treatment temperature of 700 °C, the SnO₂ doped ZnO powder was found to exhibit significantly higher photocatalytic activity than either single-phase SnO₂ or ZnO powders that were synthesized using similar processing conditions. The heightened photocatalytic activity of the SnO₂ doped ZnO was attributed to its higher specific surface area and the enhanced charge separation arising from the coupling of ZnO with SnO₂.

Monoethanolamine reclamation using electrodialysis

Monoethanolamine (MEA) is the benchmark solvent for the capture of carbon dioxide from both natural gas and flue gas streams. Despite its effectiveness in absorbing CO2, this solvent can react with impurities in the gas stream to form heat stable salts and other degradation products. These impurities can cause problems such as an increase in solvent viscosity and corrosion of the operating units. Thus, a number of approaches have been considered to mitigate the occurrence of these problems. In this paper, the use of electrodialysis as an online MEA reclamation process in a postcombustion CO2 capture facility is investigated. The study shows that high heat stable salts removal can be achieved with a high MEA recovery. However, it is necessary to limit the current density, particularly at lower salt concentrations, to reduce water splitting. The stability of the commercial ion-exchange membranes in the highly alkaline solvent is also investigated. The results show that the membranes are stable upon exposure to 30 wt % MEA for at least 4.5 months.

Hydrogel properties of electrospun polyvinylpyrrolidone and polyvinylpyrrolidone/poly(acrylic acid) blend nanofibers

Hydrogel nanofibers with high water-absorption capacity and excellent biocompatibility offer wide use in biomedical areas. In this study, hydrogel nanofibers from polyvinylpyrrolidone (PVP) and PVP/poly(acrylic acid) (PAA) blend were prepared by electrospinning and by subsequent heat treatment. The effects of post-electrospinning heat treatment and PVP/PAA ratio on hydrogel properties of the nanofibers were examined. Heat treatment at a temperature above 180°C was found to play a key role in forming insoluble and water-absorbent nanofibers. Both PVP and PVP/PAA nanofibers showed high morphology stability in water and excellent water retention capacity. The swelling ratio of PVP/PAA nanofibers declined with increasing heating temperature and decreasing PVP/PAA unit ratio. In comparison with dense casting films, these nanofiber membranes showed nearly doubled swelling ratio.

Big change questions : can we create a form of public education that delivers high standards for all students in the emerging knowledge society?

Within many Anglophone nation states there is significant debate about
the future of public education and its ongoing capacity to provide quality
education. The new knowledge economy not only challenges the position
of educators as the primary producers, disseminators and authorizers of
what is valued knowledge, but also requires them to prepare students for
new ways of working with that knowledge. In the service economies of
post-industrial Western nations, 'knowledge work' is critical to national
productivity and international competitiveness. At the same time, the
globalization logic suggests that the nation state is under threat, and therefore its role as provider of universal services such as education is also threatened.

The effect of focus on form in the written work of adult learners of Arabic

One of the key debates within SLA research circles concerns grammar
- whether and hov to include it in second language (L2) instruction. 'Noninterventionist' approaches to language leaching, which centre on focus on meaning (FonM) , have been found to be neither economical nor expedient in terms of use of learners' classtime (Long & Robinson, 1998). This paper is a study of the effects oj direct grammatical instruction within a communicative context (Focus on Form - FonF) on the accuracy rate of the use of noun-adjective agreement in the written work of adult learners of Arabic. Learning the systems oj noun/adjective agreement in Arabic presents problems for beginners since. unlike languages such as English. Arabic needs to be modified for gender, number. definiteness and case. Through teaching material and methods, first-year university English speaking students of Arabic were directly exposed to morpho-syntactic inflections relevant to noun-adjective agreement. In post-tests over an extended period. instructed students showed a higher accuracy rate of some forms than their uninstructed colleagues. suggesting focusing on form is beneficial to the Arabic learner and does not need to interrupt the communicative flow in the classroom (Ellis et al. 2001).

How practice size impacts on the implementation and dissemination of post occupancy evaluation

There has been much research on the subject of environmentally sustainable design (ESD), with emerging techniques and technologies improving rapidly and informing sustainability higher education teaching to architects and prospective architects. By examining the success of sustainable designs using post occupancy evaluations, architectural practices might also increase their knowledge of sustainable building practice. Post occupancy evaluations could be useful for improving the designs of future buildings and the design processes that generated them. This paper aims to evaluate these claims by asking: "Do sustainable design practices use the feedback gained from post occupancy evaluations?," "How does the feedback refine the design process?," "How is the information gained in these evaluations absorbed within the firm's design practices?," and, "Does the size of a practice impact on its implementation and
dissemination of POE?" This paper investigates the questions posed above through the questioning of architectural practices that have gained a reputation for environmentally sustainable design by having a strong sustainable design philosophy and/or by being recognised for this by winning a sustainability design award. The interviewed practices will have provided some form of post occupancy evaluation as a service or employed them to add to their own knowledge.

Psychosocial issues facilitating recovery post-CABG surgery

Background
The acute illness phase following coronary artery bypass graft (CABG) surgery is a difficult time for patients as they try to adjust to the physical and emotional changes brought about by surgery.
Aims
To conduct an indepth examination of psychosocial issues experienced by patients post-CABG surgery and how patients manage these psychosocial issues during their recovery.
Methods
A qualitative research approach, naturalistic inquiry, guided the study. Thirty patients were interviewed 4–5 weeks following discharge from hospital after CABG surgery and at 12 months after the initial interview.
Results
esults found that adjusting to life after surgery was difficult, and patients experienced some form of physical pain or change. An unexpected finding was the extent to which many of the patients were attuned to their post-operative physical adjustments. Patients spoke of mental and emotional changes, and coming to terms with lifestyle adjustments.
Conclusion
Study findings suggest the need for a re-examination of hospital discharge preparation and further provision and monitoring of home support services.

To stay or to go? 'At risk' young women speak about their influences and experiences in making decisions about post-compulsory schooling

Recent research indicates that young women who leave school early (ie at or before year 10) are the group most 'at risk' of becoming only marginally attached to the labour force or unemployed. Young women from low socio-economic backgrounds are more often those who 'choose' to leave schooling, often for complex reasons, some of which are only marginally connected to their schooling experiences. In order to better understand-and address-the needs of this cohort, it is necessary to examine the multi layered connections between students' lives in and out of school.

This paper reports on the initial stage of a three year ARC-funded study, 'Young women negotiating from the margins of education and work.' In interviews and focus groups, young women identified as 'at risk' of leaving school early speak about the factors that have influenced their decisions. We examine the data with specific reference to the question: what type of social capital do these young women deploy in making their choices? Recent research (Croninger & Lee, 2001) suggest that teachers' support and guidance are a form of social capital that can make a difference, particularly in regards to students from lower socio-economic backgrounds. We discuss the young women's and teachers' interview data in light of recent debates about social capital and education.

The effects of clustered data on standard error estimates in covariance structure analysis : a field data application

Purpose – The purpose of this article is to present an empirical analysis of complex sample data with regard to the biasing effect of non-independence of observations on standard error parameter estimates. Using field data structured in the form of repeated measurements it is to be shown, in a two-factor confirmatory factor analysis model, how the bias in SE can be derived when the non-independence is ignored.

Design/methodology/approach – Three estimation procedures are compared: normal asymptotic theory (maximum likelihood); non-parametric standard error estimation (naïve bootstrap); and sandwich (robust covariance matrix) estimation (pseudo-maximum likelihood).

Findings – The study reveals that, when using either normal asymptotic theory or non-parametric standard error estimation, the SE bias produced by the non-independence of observations can be noteworthy.

Research limitations/implications – Considering the methodological constraints in employing field data, the three analyses examined must be interpreted independently and as a result taxonomic generalisations are limited. However, the study still provides “case study” evidence suggesting the existence of the relationship between non-independence of observations and standard error bias estimates.

Originality/value – Given the increasing popularity of structural equation models in the social sciences and in particular in the marketing discipline, the paper provides a theoretical and practical insight into how to treat repeated measures and clustered data in general, adding to previous methodological research. Some conclusions and suggestions for researchers who make use of partial least squares modelling are also drawn.

The effect of food temperature on post-prandial metabolism in albatrosses

Heat generated by the specific dynamic action (SDA) associated with feeding is known to substitute for the thermoregulatory costs of cold-exposed endotherms; however, the effectiveness of this depends on food  temperature. When food is cooler than core body temperature, it is warmed by body heat and, consequently, imposes a thermoregulatory challenge to the animal. The degree to which this cost might be `paid' by SDA depends on the relative timing of food heating and the SDA response. We investigated this phenomenon in two genera of endotherms, Diomedea and Thalassarche albatrosses, by measuring postprandial metabolic rate following ingestion of food at body temperature (40°C) and cooler (0 and 20°C). This permitted us to estimate potential contributions to food warming by SDA-derived heat, and to observe the effect of cold food on metabolic rate. For meal sizes that were ~20% of body mass, SDA was 4.22±0.37% of assimilated food energy, and potentially contributed 17.9±1.0% and 13.2±2.2% of the required heating energy of food at 0°C for Diomedea and Thalassarche albatrosses, respectively, and proportionately greater quantities at higher food temperatures. Cold food increased the rate at which postprandial metabolic rate increased to 3.2–4.5 times that associated with food ingested at body temperature. We also found that albatrosses generated heat in excess by more than 50% of the estimated thermostatic heating demand of cold food, a probable consequence of time delays in physiological responses to afferent signals.

Particle dynamics and heat transfer at workpiece surface in heat treatment fluidised beds

The particle behaviour is studied by the analysis of particle images taken with a high speed CCD digital video camera. The comparison of particle dynamics is performed for the fluidised beds without part, with single part and with multi-parts. The results show that there are significant differences in particle behaviours both in different beds and at different locations at part surfaces. The total and radiative heat transfer coefficients at different surfaces of a metallic component in a high temperature fluidised bed are measured by a heat transfer probe developed in the present work. The principle of the heat transfer probe is to measure the change in temperature of the heated metallic piece with time and, then, to extract the heat flux and heat transfer coefficients. The structure of the probe is optimized with numerical simulation of energy conservation for measuring the heat transfer coefficient of 150~600 W/m2 K. The relationship between the particle dynamics and the heat transfer is analysed to form the basis for future more rational designs of fluidised beds as well as for improved quality control.