Conservatoire national des arts et métiers

About: Conservatoire national des arts et métiers is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Context (language use). The organization has 3573 authors who have published 7127 publications receiving 141430 citations. The organization is also known as: CNAM & Conservatoire des arts et métiers.

Toward the understanding of temperature effect on bonding strength, dimensions and geometry of 3D-printed parts

Abstract: Fused filament fabrication (FFF), which is an additive manufacturing technique, opens alternative possibilities for complex geometries fabrication. However, its use in functional products is limited due to anisotropic strength issues. Indeed, the strength of FFF fabricated parts across successive layers in the build direction (Z direction) can be significantly lower than the strength in X–Y directions. This strength weakness has been attributed to poor bonding between printed layers. This bonding depends on the temperature of the current layer being deposited—at melting temperature (Tm)—and the temperature of the previously deposited layer. It is assumed that depositing a layer at Tm on a layer at temperature around crystallization temperature (Tc) would enable higher material crystallinity and thus better bonding between previous and present layers. On the contrary, if the previous layer temperature is below Tc, material crystallinity will be low and bonding strength weak. This paper aims at studying the significant effect of temperature difference (ΔT) between previous and current deposited layers temperatures on (1) inter-layers bonding strength improvement and (2) part dimensions, geometry and structure stability. A 23% increase in the inter-layers bonding strength for previous layer temperature slightly higher than Tc reported here confirms the above assumption and offers a first solution toward the increase in inter-layers bonding strength in FFF.

Dexamethasone-induced apoptosis of mouse thymocytes: prevention by native 7alpha-hydroxysteroids.

Abstract: Dehydroepiandrosterone (DHEA) has been shown to decrease the dexamethasone (DEX)-induced apoptosis of thymocytes and to be one of the native 3-hydroxysteroids extensively 7-hydroxylated in thymus. This led us to question whether DHEA or 7-hydroxy-DHEA is responsible for the decrease in DEX-induced apoptosis of thymocytes and whether this property is shared with other native 3-hydroxysteroids and their 7-hydroxylated metabolites. Treatment of mice with DHEA or 7-hydroxy-DHEA prior to DEX led to a smaller decrease in thymus weight than with DEX alone and to a disappearance of the DEX-induced changes in thymocyte phenotypes. Thymocyte apoptosis induced by DEX treatment was significantly lowered in DHEA- and 7-hydroxy-DHEA-treated thymi, even after 18 h culture with additional 10-6 mol/L DEX. Extensive apoptosis of thymocytes cultured with 10-7 mol/L DEX was brought back to control levels when 10-5 mol/L 7-hydroxy-DHEA or 10-5 mol/L 7-hydroxy-epiandrosterone was added. After use of DHEA and epiandrosterone or pregnenolone, less significant and no significant changes were obtained, respectively. These findings imply that the 7-hydroxylation of 3-hydroxysteroids may be a prerequisite for an exquisite regulation of the thymocyte-positive selection driven by the glucocorticoids produced in thymic epithelial cells.

Ergonomics in industrially developing countries

Abstract: After introducing the concept of industrially developing countries (I.D.C), a review of the ergonomic literature, mainly produced by authors working in the I.D.C, is presented under three headings. The first part is related to basic ergonomic data: anthropometry, work at heat, limited cardio-respiratory work capacities, effects of tropical diseases, influence of shift-work, role of possible ethnic cognitive differences. Ergonomics in traditional activities is presented from evidence produced mainly in Brazil and Asia ( India, Indonesia, Philippines) by authors who are performing field studies in agriculture and cottage industries. The final part is devoted to the transfer of technology. Many factories transferred from industrialized countries to I.D.C.s provide poor results both from health and production viewpoints when they are transferred without careful ergonomical and anthropotechnological analysis and recommendations. At the opposite, very successful results are frequently observed in the ‘ anthropo...