Postprandial utilization of energy susbtrates by a tropical catfish, Holosternum littorale : indirect calorimetry analysis

Indirect calorimetry method was used to measure postprandial utilization of energy substrates by atipa, #Hoplosternum littorale (#Callichthyidae, Siluriform). A model was adjusted to the data on respiratory exchanges and nitrogen excretion for this purpose. As for other fish species, protein was actively catabolized after feeding during the 60 hr measurement time. As long as carbohydrates were available, atipa was also able to use these substrates for its energy metabolism. A gradual increase of contribution of lipids was then noticed. Over a 24 hr period following the food intake, a 30 g fish catabolized 90 mg of proteins and 43 mg of carbohydrates. At the same time, the results led to a synthesis of 3.7 mg of fat. An estimation of the increase of the global metabolism associated to food intake was obtained from integration of the exponential terms of the models. (Résumé d'auteur

Low energy high angular resolution neutral atom detection by means of micro-shuttering techniques: the BepiColombo SERENA/ELENA sensor

The neutral sensor ELENA (Emitted Low-Energy Neutral Atoms) for the ESA cornerstone BepiColombo mission to Mercury (in the SERENA instrument package) is a new kind of low energetic neutral atoms instrument, mostly devoted to sputtering emission from planetary surfaces, from E ~20 eV up to E~5 keV, within 1-D (2x76 deg). ELENA is a Time-of-Flight (TOF) system, based on oscillating shutter (operated at frequencies up to a 100 kHz) and mechanical gratings: the incoming neutral particles directly impinge upon the entrance with a definite timing (START) and arrive to a STOP detector after a flight path. After a brief dissertation on the achievable scientific objectives, this paper describes the instrument, with the new design techniques approached for the neutral particles identification and the nano-techniques used for designing and manufacturing the nano-structure shuttering core of the ELENA sensor. The expected count-rates, based on the Hermean environment features, are shortly presented and discussed. Such design technologies could be fruitfully exported to different applications for planetary exploration.Comment: 11 page

Laser Patterning Pretreatment before Thermal Spraying: A Technique to Adapt and Control the Surface Topography to Thermomechanical Loading and Materials

Coating characteristics are highly dependent on substrate preparation and spray parameters. Hence, the surface must be adapted mechanically and physicochemically to favor coating–substrate adhesion. Conventional surface preparation methods such as grit blasting are limited by surface embrittlement and produce large plastic deformations throughout the surface, resulting in compressive stress and potential cracks. Among all such methods, laser patterning is suitable to prepare the surface of sensitive materials. No embedded grit particles can be observed, and high-quality coatings are obtained. Finally, laser surface patterning adapts the impacted surface, creating large anchoring area. Optimized surface topographies can then be elaborated according to the material as well as the application. The objective of this study is to compare the adhesive bond strength between two surface preparation methods, namely grit blasting and laser surface patterning, for two material couples used in aerospace applications: 2017 aluminum alloy and AISI 304L stainless steel coated with NiAl and YSZ, respectively. Laser patterning significantly increases adherence values for similar contact area due to mixed-mode (cohesive and adhesive) failure. The coating is locked in the pattern

Influence de la nature des glucides alimentaires sur l'utilisation de 2 sources protéiques par la truite Arc-en-ciel élevée à 8° ou 18°C

International audienc

3D unsteady computations of evaporative instabilities in a sessile drop of ethanol on a heated substrate

International audienceDroplets are ubiquitous and have been studied for a century; however, their internal flow pattern and related instabilities that occur in the course of evaporation are not fully understood yet. In this paper, we report our investigation results on an ethanol drop evaporating onto a heated substrate under weightlessness conditions and with a pinned contact line. They have been obtained from both experiments and 3D unsteady computations in order to determine what kind of instabilities develop. Our one-sided model demonstrates quantitative agreement with experiments and confirms that experimentally observed instabilities are driven by thermo-capillary stress and not by the gas con-vection. Post-processed infrared images drawn from computations led us to conclude that the experimentally observed thermo-convective instabilities, which look very similar to hydrothermal waves in the infrared spectrum, are actually nothing else than unsteady Benard-Marangoni instabilities