Apprentissage de la stéréochimie : raisonnements et difficultés

Résumé — Nous présentons ici notre travail de recherche qui a pour objet l’enseignement et l’apprentissage de la stéréochimie lors de deuxième année de l’enseignement supérieur Marocain.Il semble exister un malaise dans l'enseignement et l’apprentissage de la chimie organique: une discipline reconnue comme difficile, des démarches d'enseignement dogmatiques et cumulatives, des étudiants qui mémorisent plus qu'ils ne comprennent et qui ont du mal à mettre en relation les différents éléments théoriques, une utilisation problématique du symbolisme, et une certaine insatisfaction des enseignants.Les résultats des recherches antérieures nous conduisent à orienter notre travail autour de certaines activités cognitives (communication, traitement et conversion) que permettent les systèmes de Cram et de Newman. Les activités choisies se rapportent aux capacités attendues des étudiants, à la fin de l’apprentissage de la stéréochimie.Apprentissage, stéréochimie, systèmes sémiotiques, étudiant marocai

Application of essential oil of Anvillea radiata as a green corrosion inhibitor for steel in 1M HCL solution

International audienc

Experimental and theoretical study on corrosion inhibition of new synthesized menthone derivatives (Menthopyrazole compounds) for mild steel in 1 M HCl solution

International audienc

Chemical composition, adsorption properties and corrosion inhibition on mild steel of mentha rotundifolia L. essential oil

International audienc

Epididymal Cysts in Childhood - Conservative or Surgical Approach?

The aim of the study. To decide on the accurate way of treatment and to establish criteria for operation in boys with pubertal epididymal cysts (ECs).Material and methods. Results of scrotal ultrasound of 363 boys and adolescents, aged 2 months to 18 years, were reviewed retrospectively.Results. Of all 363 patients with scrotal ultrasound 59 (16.2%) at mean age of 14.03 yrs had ECs. The EC incidence increased with age and 42 out of 124 boys (33.8%) older than 14 yrs had cysts (chi2=27.627, p=0.000). Out of 59 patients, in 30 (50.8%) cysts were diagnosed incidentally at the time of scrotal US, 29 boys (49.2%) presented with scrotal mass and/or pain. 31 patients with ECs (52.5%) underwent elective surgery and the remaining 28 boys (47.5%) received conservative treatment. The age of boys with ECs who underwent surgery ranged from 8 to 18 years (mean 14.32). The age range of patients treated conservatively was 7-18 (mean 13.71). There was no statistical difference in age between boys treated surgically and conservatively (t=0.924, p=0.36). ECs resolved in 17 patients out of 28 boys treated conservatively, in remaining 11 boys the size of cysts was stabile and they remain asymptomatic. Clinical and ultrasonographic follow-up were carried out from 11 months to 5 years.Conclusions. ECs are more common in older boys (over 14 years). Management of ECs smaller than 10 mm should be conservative with clinical and ultrasound controls, leaving surgery for cysts increasing in size over 10 mm which did not involute with time