Relationships between microstructure, mechanical and dielectric properties of different alumina materials

International audienceDifferent alumina materials were elaborated in order to vary microstructural parameters (grain size, densification, porosity, inter-granular phase). These ceramic materials were then characterized from the mechanical point of view (hardness, toughness, friction and wear) and dielectric breakdown. The comparison of these various results shows that, for all these properties, the grain size and also, the nature of the secondary phases and the microstructural parameters were the most significant. Moreover, from the tribological point of view, the dielectric characteristic of materials (breakdown strength) has a fundamental role in the creation of agglomerated wear debris (“third body”) and its properties: a finely agglomerated third body will be obtained for high breakdown strength. Such third body will be able to protect the substrate and thus to reduce later wear. In the same logic a correspondence between breakdown strength and toughness was established, thus confirming the existence of mechanical–electrical correlation for non-conductive materials

Management of the Congenital Aneurysm of the Left Ventricle Associated with Mitral Insufficiency in a Child: A Case Report

The combination of congenital left ventricular aneurysm associated with mitral insufficiency is rare. We describe the case of a girl aged 11 years, bearing these two entities simultaneously. Aneurysmal resection of the left ventricle was performed with Dor technic to allow remodelation of the anatomy of the left ventricle. Mitral annuloplasty was performed through a transseptal approach. Three months after surgery, the child presents a good myocardial contractility without mitral regurgitation and normal ejection fraction

Microbial Fuel Cells: From biomass (waste) to electricity

International audienceThe microbial fuel cell (MFC) technology could provide opportunities for electricity generation from the organic matter. Indeed a MFC can produce electric energy by converting a part of the chemical energy contained in biodegradable substrates through the metabolic activity of bacteria. This could be both economically and environmentally effective when the organic matter does not have any intrinsic value as in the case of domestic or industrial waste waters. This paper presents the principle and current development in the domain of MFC and gives an idea of potential future applications

Simulation of the boriding kinetics of Fe 2

The present work evaluates, using the two approaches, the growth kinetics of Fe2B boride layers generated at the surface of iron via the paste-boriding for different temperatures (1223, 1253,1273 and 1323 K) and a variable treatment time : (1, 2, 4 and 6 h). Using the mass balance equation at the (Fe2B/substrate) interface under certain assumptions and considering the effect of the boride incubation time, it was possible to estimate the value of parabolic growth constant at the (Fe2B/substrate) interface. As a second approach, the dimensional analysis, based on the Buckingham- Pi theorem, was also used to study the boriding kinetics of Fe2B layers. A good agreement was observed between the experimental parabolic growth constants and the predicted ones from the first approach (i.e. the mass balance equation), on the basis of experimental data taken from the literature. Moreover, both approaches can serve as a tool to select the optimum thicknesses of Fe2B layers according to the practical use in industry

Simulation of the boriding kinetics of Fe

The present work evaluates, using the two approaches, the growth kinetics of Fe2B boride layers generated at the surface of iron via the paste-boriding for different temperatures (1223, 1253,1273 and 1323 K) and a variable treatment time : (1, 2, 4 and 6 h). Using the mass balance equation at the (Fe2B/substrate) interface under certain assumptions and considering the effect of the boride incubation time, it was possible to estimate the value of parabolic growth constant at the (Fe2B/substrate) interface. As a second approach, the dimensional analysis, based on the Buckingham- Pi theorem, was also used to study the boriding kinetics of Fe2B layers. A good agreement was observed between the experimental parabolic growth constants and the predicted ones from the first approach (i.e. the mass balance equation), on the basis of experimental data taken from the literature. Moreover, both approaches can serve as a tool to select the optimum thicknesses of Fe2B layers according to the practical use in industry

Microfluidic immunomagnetic cell separation using integrated permanent micromagnets

International audienceIn this paper, we demonstrate the possibility to trap and sort labeled cells under flow conditions using a microfluidic device with an integrated flat micro-patterned hard magnetic film. The proposed technique is illustrated using a cell suspension containing a mixture of Jurkat cells and HEK (Human Embryonic Kidney) 293 cells. Prior to sorting experiments, the Jurkat cells were specifically labeled with immunomagnetic nanoparticles, while the HEK 293 cells were unlabeled. Droplet-based experiments demonstrated that the Jurkat cells were attracted to regions of maximum stray field flux density while the HEK 293 cells settled in random positions. When the mixture was passed through a polydimethylsiloxane (PDMS) microfluidic channel containing integrated micromagnets, the labeled Jurkat cells were selectively trapped under fluid flow, while the HEK cells were eluted towards the device outlet. Increasing the flow rate produced a second eluate much enriched in Jurkat cells, as revealed by flow cytometry. The separation efficiency of this biocompatible, compact micro-fluidic separation chamber was compared with that obtained using two commercial magnetic cell separation kit