Isosorbide is obtained by dehydration of sorbitol and therefore can be considered as a valuable product from biomass. The acid‐catalyzed reaction gives rise to different anhydro‐compounds, but also to polymer‐like products. Kinetics of sorbitol decrease, followed with the help of HPLC, shows, remarkedly, the different reactions taking place during the dehydration. Physiocochemical properties of isosorbide are also discussed: melting temperature, specific gravity, solubility. Emphasis is put on stereochemistry aspect, pointing out the endo‐exo position of hydroxyl groups versus those of other isomers: exo‐exo for isoiodide and endo‐endo for isomannide. Some other properties such as: hygroscopicity ant thermal stability are also discussed. The chemical reactivity of the molecule is then described and some reactions analyzed, proving the interest of the cyclic conformation. Finally, a review of known applications is presented.
Approches de la catégorisation en éducation Comment analyser ce que font les enseignants dans la préparation de leurs cours ? Ébauche d'un cadre conceptuel How to analyze what teachers do to prepare their lessons? Sketching a conceptual frame
Dans ce texte, nous proposons de considérer comme objectif de formation une capacité spécifiquement construite dans les formations technologiques : la particularisation. Ce point de vue, pour se situer en didactique des génies techniques, prend volontairement le contre-pied des recherches concernant les capacités transversales comme objectifs de formation. Nous proposons ensuite un schéma d'organisation des formations à l'analyse de systèmes techniques pour préciser ce qui constitue la capacité de particularisation et nous en déduisons des révélateurs observables de l'existence de cette capacité. Il apparaît empiriquement qu'elle existe peu pour un échantillon d'étudiants en Licence de technologie mécanique, et nous l'expliquons par des défauts de connaissances des étudiants et les modes d'intervention pédagogiques de l'enseignant. A partir de ces résultats, mais également à partir de nos expériences de praticiens, nous pensons que des évolutions de contenus et de modes d'intervention pédagogique sont donc à imaginer pour les formations technologiques supérieures.
Executive Summary:lt is a premise of this study that the objective of training is particularizationthat is, a capacity that is specifically constructed in technical education programs. Within the framework of engineering education, this perspective deliberately runs counter to research on cross-curricular (transferable) skills as constituting the objectives of training. In terms of teaching methods and evaluation, the interest of such issues appears to consist precisely in characterizing what each discipline specifically has to offer, rather than necessarily and immediately seeking to construct metaknowledge common to all disciplines.This study then presents PYSTILE, a schema used to categorize technical knowledge from a training perspective. The fondamental data that must be acquired by specialists of a given field can be classified according to four categories: the operational environment; industrial products; simulated abjects; and the range of performance values. In particular, this schema serves as a basis for elaborating the components of the capacity to particularize. This portion of the analysis begins by deducing the observable features that reveal the existence of this capacity according to concepts of performance and primary failure mode. Based on the observations of 12 groups of two or three students, the gathered data suggest, empirically, that the capacity of particularization hardly exists. These results lead in turn to a fourth empirical findingnamely, that students have not developed this capacity at the educational level known in France as Licence de technologie mécanique (a degree awarded after one year of a Master's program in Mechanical Technology). Based on the authors' own observations, this incapacity is due to certain gaps in students' knowledge and to the maladapted teaching approach adopted by instructors. To begin with, students are unfamiliar with either the idea of operational environment or the concept of primary failure m...
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