Exploring factors affecting undergraduate medical students’ study strategies in the clinical years: a qualitative study

The aim of this study is to explore the effects of clinical supervision, and assessment characteristics on the study strategies used by undergraduate medical students during their clinical rotations. We conducted a qualitative phenomenological study at King Saud Bin Abdulaziz University for Health Sciences, College of Medicine, Riyadh, Saudi Arabia during the period from November 2007 to December 2008. We conducted semi-structured focus groups interviews with students and conducted individual interviews with teachers and students to explore students’ and clinical teachers’ perceptions and interpretations of factors influencing students’ study strategies. Data collection was continued until saturation was reached. We used Atlas-ti Computer Software (Version 5.2) to analyse the data, apply the obtained themes to the whole dataset and rearrange the data according to the themes and sub-themes. Analysis of data from interviews with twenty-eight students and thirteen clinical supervisors yielded three major themes relating to factors affecting students’ study strategies: “clinical supervisors and supervision”, “stress and anxiety” and “assessment”. The three themes we identified played a role in students’ adoption of different study strategies in the “community of clinical practice”. It appeared that teachers played a key role, particularly as assessors, clinical supervisors and as a source of stress to students

Cluster properties of sensitized grain boundaries in Type 304 stainless steel

Electron Backscatter Diffraction (EBSD) and Image Analysis (IA) techniques have been coupled with Double Loop-Electrochemical Potentiokinetic Reactivation (DL-EPR) testing to characterize the development of sensitized grain boundary clusters in Type 304 stainless steel. DL-EPR testing revealed differences in the sensitization response of thermo-mechanically processed microstructures, despite similar grain size and grain boundary character distributions (GBCD). The same sensitization treatment produced different distributions of sensitized grain boundary clusters, and susceptible boundary clusters percolated through all microstructures after sensitization treatments of 4 hrs at 650°C. Assessment of the connectivity of ∑3 n (1≤n≤3) grain boundaries in EBSD maps showed a trend to longer clusters with increasing ∑3 n (1≤n≤3) fractions. A comparison to DL-EPR data showed the attacked grain boundary networks were generally in excess of 80% of the potentially susceptible grain boundary fraction. © 2009 by NACE International

The influence of low-strain thermo-mechanical processing on grain boundary network characteristics in type 304 austenitic stainless steel.

Grain boundary engineering of austenitic stainless steel, through the introduction of plastic strain and thermal annealing, can be used to develop microstructures with improved resistance to inter-granular degradation. The influence of low-strain thermo-mechanical processing on grain boundary network development, with systematic variations of annealing treatments, has been investigated. Three stages of the microstructure development during grain boundary engineering in low-strain processing conditions are identified, and correlated with changes in grain boundary character and deviation distributions. Low-energy connected length segments at triple junctions, which have been proposed to be responsible for crack bridging during inter-granular stress corrosion cracking, can be influenced by the choice of the annealing treatment parameters. The development of individual grain boundary length segments of different character showed consistent trends with increasing grain size. Crack length predictions are consistent with the beneficial effect of designing microstructures with high fractions of twin grain boundaries and smaller grain size

Surface grain boundary engineering of shot-peened type 304 stainless steel

The effect of thermal annealing on shot-peened Type 304 stainless steel has been examined using electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). The objective was to evaluate the potential for surface property control by grain boundary engineering. The near surface microstructure of shot-peened material showed a gradual change of the grain boundary character distribution with depth. Twin (∑3) and higher order twin grain boundaries (∑9, ∑27) identified closer to the shot-peened surface had significant deviations from their optimum misorientation. The subsequent application of annealing treatments caused depth-dependent changes of the near surface microstructure, with variations in grain size, low ∑ CSL grain boundary populations and their deviation from optimum misorientation. Microstructure developments were dependent on the applied heat treatment, with the near surface microstructures showing similarities to microstructures obtained through bulk thermo-mechanical processing. Shot peening, followed by annealing, may therefore be used to control the near surface microstructure of components. © 2007 Springer Science+Business Media, LLC

Grain boundary engineering for crack bridging: A new model for intergranular stress corrosion crack (IGSCC) propagation

This chapter introduces a new intergranular stress corrosion crack (IGSCC) propagation model based on grain bridging by crack resistant, low energy grain boundary, (GB), and their related triple junction density (TJD). A stochastic model considers the frequency of immune GBs with respect to the microstructural probability of arresting a crack at a TJ. This is reflected in the maximum critical crack length, and influencing factors such as grain size and total probability of crack arrest. The observation of grain bridging has suggested a new approach of predicting intergranular stress corrosion crack length distributions. The key premise of this model is that bridges arise from the local arrest at "cul-de-sac" (2-CSL TJ) or unfavorably orientated triple junctions (1-CSL TJ). Crack arrest by a single junction is not expected to significantly affect the behavior of a crack with a size greater than several grains. The cumulative effect of grain bridging gives rise to a shielding stress, which reduces the stress intensity factor at the crack tip. Several microstructure dependent factors lead to the shielding stress. First, the number of bridges per unit area is assumed to vary in proportion to the resistance factor. Second, the bridge size, and thus its contribution to the shielding stress, depends on the grain size, which is related to the spacing of effective TJs. Finally, the degree of shielding is assumed to build up and then saturate at steady state with increasing crack length. © 2008 Elsevier Ltd All rights reserved

Time-dependent in situ measurement of atmospheric corrosion rates of duplex stainless steel wires

Corrosion rates of strained grade UNS S32202 (2202) and UNS S32205 (2205) duplex stainless steel wires have been measured, in situ, using time-lapse X-ray computed tomography. Exposures to chloride-containing (MgCl2) atmospheric environments at 50 °C (12–15M Cl− and pH ~5) with different mechanical elastic and elastic/plastic loads were carried out over a period of 21 months. The corrosion rates for grade 2202 increased over time, showing selective dissolution with shallow corrosion sites, coalescing along the surface of the wire. Corrosion rates of grade 2205 decreased over time, showing both selective and pitting corrosion with more localised attack, growing preferentially in depth. The nucleation of stress corrosion cracking was observed in both wires