Top trois des méthodes pour détecter Pseudomonas aeruginosa, La troisième va vous surprendre !

International audienc

Epidémie d'infections du site opératoire à Serratia marcescens associée à l'utilisation d'une sonde d'échographie

International audienc

Rayleigh–Taylor instability between unequally stratified layers

In this article, we explore the development and mixing that results from Rayleigh–Taylor instability between two layers. Unlike the classical problem, one of the two layers initially has a stable density stratification, while the density of the fluid in the other is uniform. The results presented here are from low Atwood number experiments with incompressible fluids, although there is an analogy between this case and low accelerations of compressible fluids that result in hydrostatic gradients that differ significantly. In both scenarios, the instability growth is asymmetric. For the present case, mixing will occur throughout the region initially occupied by the layer of uniform density but, depending on the strength of the stratification compared with the density difference across the initial Rayleigh–Taylor-unstable interface, the mixing may be arrested by the stratification before it reaches the lower boundary of the domain. We propose a simple model for the growth of the instability and see that it captures the qualitative behaviour. The final state comprises a weakly stratified layer bounded on one side by the remnant of the initially stratified layer. The structure of this weak stratification is seen to be consistent with the idea of maximal configurational entropy for the mixing zone. Ultimately, the efficiency of this mixing process is found to follow the pattern expected for ‘perfect mixing’ equivalent, but achieves only 94% of the corresponding value

Etude de l'application et de l'efficacité des mesures barrières pour prévenir la transmission nosocomiale de la grippe saisonnière au CHU de Caen

CAEN-BU Médecine pharmacie (141182102) / SudocLYON1-BU Santé (693882101) / SudocSudocFranceF

Top trois des méthodes pour détecter Pseudomonas aeruginosa, La troisième va vous surprendre !

International audienc

Potentiality of zinc oxide nanosensor prepared by a new electroplating method on p-Si (1 1 1) wafer substrate

Nanostructured ZnO thin films were deposited on p-Si (1 1 1) substrates using a new electrodeposition method. Electrical and sensing properties were investigated. Variations of the resistance measured between two points of the ZnO film, have shown a maximum sensitivity (δ = 10) in the presence of gas ‹CO› and (δ = 14,70) in the presence of ‹C2H5OH› at a temperature of 300 °C. Therefore, we can say that the sensitivity tests indicate that the sensor consisting of a nanometer zinc oxide layer is more efficient at temperatures beyond 100 °C. Moreover, the sensing element has demonstrated a good response to reducing gases species. Keywords: Electrodeposition, ZnO, Ethanol/carbon monoxide sensor, Response/recovery times, Sensitivit

Growth and characteristics of ZnO nano-aggregates electrodeposited onto p-Si(1 1 1)

In this paper we study nanocrystalline zinc oxide thin films produced by oxidation of electrodeposited zinc nanolayers on a monocrystalline p-Si(1 1 1) substrate. The electrolyte used is ZnCl2, an aqueous solution of 4 × 10−2 mol/l concentration. Several deposits were made for various current densities, ranging from 13 mA/cm2 to 44 mA/cm2, flowing through the solution at room temperature. A parametric study enabled us to assess the effect of the current density on nucleation potential and time as well as zinc films structure. The grazing incidence X-ray diffraction (GIXD) revealed that both Zn and ZnO films are polycrystalline and nanometric. After 1-h oxidation of zinc films at 450 °C in the open air, the structural analyses showed that the obtained ZnO films remained polycrystalline with an average crystal size of about 47 nm and with (1 0 0), (0 0 2) and (1 0 1) as preferential crystallographic orientations