Unexpected Field Evaporation Sequence in γ\gamma-TiAl

In atom probe tomography (APT), atoms from the surface of a needle shape specimen are evaporated under a high electric field and analyzed via time of flight mass spectrometry and position sensitive detection. 3D reconstruction of the atom positions follows a simple projection law, which can sometimes lead to artifacts due to deviation from an assumed ideal evaporation sequence. Here, we revisit the evaporation behavior of [001]-oriented $\gamma$-TiAl using a full-dynamics simulation approach empowered by molecular dynamics. Without any knowledge of charge states or assumptions about evaporation fields, we successfully reproduced the lack of distinct Al and Ti layers observed in reconstructions of experimental data which is traditionally attributed to the retention of Al on the evaporating surface. We further showed that a step-wise bond breaking process of Ti in contrast to the simultaneous bond breaking of Al explains the seemingly counterintuitive preferential evaporation of the strongly bonded Ti atoms

Analytical characterisation of oxide dispersion strengthened steels for fusion reactors

Reduced activation ferritic/martensitic and ferritic steels strengthened by a dispersion of oxide nanoparticles have been considered viable structural materials for fusion applications above 550°C. However, the microstructural stability and mechanical behaviour of these steels subjected to the aggressive operating conditions of these reactors are not well known. An accelerated development of these materials is crucial if they are going to be used in future power reactors. Then, it is indispensable to understand their atomic scale evolution under high temperature and irradiation conditions. The present paper reviews how the combination of transmission electron microscopy and atom probe tomography has been successfully applied for the characterisation of these steels at the near atomic scale, to reveal the nanoparticle structure, grain boundary chemistry and void distribution

Towards an understanding of tensile deformation in Ti-based bulk metallic glass matrix composites with BCC dendrites

The microstructure and tension ductility of a series of Ti-based bulk metallic glass matrix composite (BMGMC) is investigated by changing content of the β stabilizing element vanadium while holding the volume fraction of dendritic phase constant. The ability to change only one variable in these novel composites has previously been difficult, leading to uninvestigated areas regarding how composition affects properties. It is shown that the tension ductility can range from near zero percent to over ten percent simply by changing the amount of vanadium in the dendritic phase. This approach may prove useful for the future development of these alloys, which have largely been developed experimentally using trial and error

Évaluation de la lisibilité et de la fluidité de l’écriture manuelle d’élèves franco-québécois de 1re et 2e année du primaire

Contexte. Au Québec, les difficultés d’écriture manuelle et leur impact fonctionnel constituent le principal motif de référence en ergothérapie pour les enfants en milieu scolaire. Pour évaluer le rendement de l’écriture manuelle, plusieurs critères peuvent être utilisés, tels que la lisibilité et la fluidité. Toutefois, aucune valeur de référence n’existe pour situer et comparer correctement la lisibilité et la fluidité de l’écriture manuelle auprès d’enfants franco-québécois. Objectif. L’étude visait à développer un guide d’évaluation de la lisibilité de l’écriture manuelle, à déterminer des valeurs de référence de la lisibilité et de la fluidité pour des enfants francophones et à comparer les scores entre les filles et les garçons. Méthodologie. Il s’agit d’une analyse secondaire de données provenant d’une étude descriptive transversale réalisée auprès d’élèves de 1re et de 2e année du primaire. Les valeurs de référence de la lisibilité et de la fluidité ont été calculées à partir d’échantillons provenant de tâches en copie de près et à l’aide du guide développé dans la présente étude. Résultats. Les critères du guide d’évaluation de la lisibilité offrent une excellente fidélité inter-juges pour la 1re année du primaire et une bonne fidélité interjuges pour la 2e année. De plus, des valeurs de référence ont été obtenues pour la lisibilité et la fluidité. Une différence significative entre les scores de lisibilité des filles et des garçons de 2e année a été relevée. Conséquences. Le guide d’évaluation et les valeurs de référence améliorent la rigueur de l’évaluation ergothérapique de l’écriture manuelle des enfants franco-québécois, et ce, grâce à des critères observables et mesurables bien définis. _________________________________________________________________________________________________________________ Background. In Quebec, handwriting difficulties and their functional impacts are the main reason for referral of children to occupational therapy for children in school settings. To evaluate handwriting performance, several criteria can be used such as legibility and accuracy. However, there are no norms to properly compare handwriting legibility and accuracy among French-speaking children in Québec. Purpose. The purpose of the study was to develop a handwriting legibility assessment guide, to develop norms for legibility and accuracy for francophone children, and to compare scores between boys and girls. Methods. This is a secondary analysis of data from a cross-sectional descriptive study of grade 1 and grade 2 students. Norms for legibility and accuracy were calculated from close-copy tasks samples and using the guide developed in this study. Findings. The criteria used in the handwriting legibility assessment guide offer excellent inter-rater reliability for grade 1 students and good inter-rater reliability for grade 2 students. Norms were also obtained for legibility and fluency. There was a significant difference between the legibility score of grade 2 boys and girls. Consequences. The assessment guide and norms increase the rigour of the occupational therapy evaluation of handwriting for Quebec francophone children, using well-defined observable and measurable criteria

Évaluation de la lisibilité et de la fluidité de l’écriture manuelle d’élèves franco-québécois de 1re et 2e année du primaire

Contexte. Au Québec, les difficultés d’écriture manuelle et leur impact fonctionnel constituent le principal motif de référence en ergothérapie pour les enfants en milieu scolaire. Pour évaluer le rendement de l’écriture manuelle, plusieurs critères peuvent être utilisés, tels que la lisibilité et la fluidité. Toutefois, aucune valeur de référence n’existe pour situer et comparer correctement la lisibilité et la fluidité de l’écriture manuelle auprès d’enfants franco-québécois. Objectif. L’étude visait à développer un guide d’évaluation de la lisibilité de l’écriture manuelle, à déterminer des valeurs de référence de la lisibilité et de la fluidité pour des enfants francophones et à comparer les scores entre les filles et les garçons. Méthodologie. Il s’agit d’une analyse secondaire de données provenant d’une étude descriptive transversale réalisée auprès d’élèves de 1re et de 2e année du primaire. Les valeurs de référence de la lisibilité et de la fluidité ont été calculées à partir d’échantillons provenant de tâches en copie de près et à l’aide du guide développé dans la présente étude. Résultats. Les critères du guide d’évaluation de la lisibilité offrent une excellente fidélité inter-juges pour la 1re année du primaire et une bonne fidélité interjuges pour la 2e année. De plus, des valeurs de référence ont été obtenues pour la lisibilité et la fluidité. Une différence significative entre les scores de lisibilité des filles et des garçons de 2e année a été relevée. Conséquences. Le guide d’évaluation et les valeurs de référence améliorent la rigueur de l’évaluation ergothérapique de l’écriture manuelle des enfants franco-québécois, et ce, grâce à des critères observables et mesurables bien définis. _________________________________________________________________________________________________________________ Background. In Quebec, handwriting difficulties and their functional impacts are the main reason for referral of children to occupational therapy for children in school settings. To evaluate handwriting performance, several criteria can be used such as legibility and accuracy. However, there are no norms to properly compare handwriting legibility and accuracy among French-speaking children in Québec. Purpose. The purpose of the study was to develop a handwriting legibility assessment guide, to develop norms for legibility and accuracy for francophone children, and to compare scores between boys and girls. Methods. This is a secondary analysis of data from a cross-sectional descriptive study of grade 1 and grade 2 students. Norms for legibility and accuracy were calculated from close-copy tasks samples and using the guide developed in this study. Findings. The criteria used in the handwriting legibility assessment guide offer excellent inter-rater reliability for grade 1 students and good inter-rater reliability for grade 2 students. Norms were also obtained for legibility and fluency. There was a significant difference between the legibility score of grade 2 boys and girls. Consequences. The assessment guide and norms increase the rigour of the occupational therapy evaluation of handwriting for Quebec francophone children, using well-defined observable and measurable criteria

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

The Role of Deformation in the Oxidation Behavior of Binary Nickel-Chromium Alloys

Nickel-based alloys are well suited for high temperature applications due to their retention of mechanical performance at elevated temperatures; however, these high temperatures are also conducive to accelerated oxidation in these alloys. Oxidation of these alloys can be mitigated by the addition of chromium to the alloy composition and the use of deformation that provides short-circuit diffusion pathways to the surface allowing the rapid formation of protective oxide scales. The beneficial effects of deformation on oxide scale protection have been widely observed in nickel alloy systems, but the fundamental mechanisms on the microscale and nanoscale remain poorly understood. We characterized alloy and scale microstructures developing in model Ni alloys with varying levels of deformation during oxidation at intermediate and high temperatures to establish a mechanistic understanding and advance the current framework for oxidation resistant alloy design.http://deepblue.lib.umich.edu/bitstream/2027.42/176951/1/NiCrPaper-cookeam_-_Aaron_Cooke.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/176951/2/NiCrPosterforDesignExpo-cookeam.pptx_-_Aaron_Cooke.pd