Les glomérulopathies juvéniles du chien

L'insuffisance rénale est une cause majeure de consultation en médecine vétérinaire. Les glomérulopathies précèdent souvent le développement d‟une insuffisance rénale. Un type particulier de glomérulopathie touche les jeunes animaux : les glomérulopathies juvéniles. Au cours des dernières années les connaissances et l‟intérêt vis-à-vis de ces affections ont fortement progressés. Ce diagnostic reste cependant une véritable gageure. Les signes cliniques propres à ces glomérulopathies peuvent être mis en évidence : protéinurie, croissance réduite, oedème… La prise en charge de ces glomérulopathies juvéniles est essentielle dans le but de préserver au mieux la fonction rénale de ces jeunes animaux. Dans ce travail, les bases anatomiques du rein et la physiologie sont abordées de même que la présentation clinique et biologique des glomérulopathies juvéniles canines au sens large. La troisième partie s‟intéresse en détail aux glomérulopathies juvéniles rapportées dans la littérature vétérinaire : la dysplasie rénale et la télangiectasie, les glomérulonéphrites, la glomérulonéphropathie membraneuse, les amyloïdoses et les glomérulopathies primaires dont, entre autres, les néphropathies héréditaires et la glomérulopathie mésangioproliférative du Dogue de Bordeaux

An investigation into the tribology and corrosion barrier performance of thin multilayer PVD films

As surface engineering develops, the methods of applying coatings and the materials used have improved significantly. One method of coating deposition that is becoming increasingly popular is physical vapour deposition (PVD). This research investigates PVD coatings of single layered systems, dual layered systems and multilayered systems with varying layer thicknesses. The properties of the coatings are investigated along with the dependence of those properties on the coating materials, the coating architecture, the hardness and surface finish of the substrates used as well as the deposition conditions. Tests were carried out on the coatings to investigate their tribological and corrosion resistant properties compared against industry standard benchmark coatings of electrodeposited chromium and nickel respectively. The base materials chosen were as follows: CrN (hard wearing) and Graphit-iC (low friction) for the durable and low friction coatings; corrosion resistant IN625 and chromium for the scratch and corrosion resistant coatings. The results showed that multilayering can be an effective tool for increasing the hardness and scratch resistance of a coating system; however, no benefit was seen in terms of the wear and corrosion resistance of the selected coating systems through multilayering. In terms of corrosion behaviour of the coated systems, the coatings themselves were corrosion resistant, and therefore the system behaviour depends upon the barrier properties of the PVD films. PVD coatings contain growth defects which provide a route for exposure of the substrate to the corrosive media. Irrespective of the film architecture, the substrate surface finish was seen to play a significant role in determining defect density, resulting in a lower defect density for coatings deposited on substrates with a finer surface finish, which resulted in an improvement in the corrosion barrier properties of the resulting films

Proyecto de incorporación de colectores solares en proceso industrial para reducción del consumo energético

Proyecto Integrador (II)--FCEFN-UNC, 2016Expone el desarrollo de una propuesta de incorporación de Colectores Solares para el calentamiento de agua en el proceso productivo de la planta pintura de la empresa multinacional situada en Córdoba IVECO. Logra un acercamiento de las energías limpias, particularmente la solar, a la industria loca

Sliding wear of a self-mated thermally sprayed chromium oxide coating in a simulated PWR water environment

Bearing surfaces in the primary circuit of pressurized water reactors (PWR) are prone to damage due to aggressive chemical and tribological conditions under which they operate, and a wide range of materials have been examined in this regard. One of the most promising candidates is chromium oxide in the form of a thermally spayed coating, and in this work, the behaviour of a commercially available Cr2O3 coating in self-mated sliding was considered. Tests consisted of a number of start-stop cycles of sliding between a crowned pin and a rotating disc in a water environment in an autoclave in an attempt to simulate the most aggressive phase of bearing run-up and run-down. Wear and damage mechanisms were examined at temperatures from ambient up to 250 C (a representative PWR environment). Samples were characterized before and after wear testing using mass measurements, profilometry, X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM) and X-ray photoelectron spectroscopy (XPS). Across the temperature range, wear was mild, with no evidence of coating delamination. A five-fold increase in wear was observed between 80 C and 250 C (with wear depths of generally less than 8 µm being observed on the disc samples even at the higher temperature), despite there being only very small changes in hardness of the coating over the same temperature range. Debris was observed on the wear tracks following testing, with the evidence together suggesting that this debris was a very fine-grained mixture of Cr2O3 and amorphous -CrOOH, a corrosion product of Cr2O3

The Infra‐Red Absorption Spectrum of Propane

Of the twenty‐seven internal degrees of freedom of propane, all nondegenerate, twenty‐two may appear as fundamental absorption bands. These bands fall into three symmetry classes, designated A1, B1 and B2, and distinguishable by their characteristic contours. Because of overlapping, however, it is impossible in many cases to determine their positions precisely. This is especially true in the regions of the C☒H valence and deformation frequencies. Some ten or twelve fundamental bands may be identified with confidence as well as a number of combinations. An A1 band at 870 cm—1 and a B2 band at 748 cm—1 have been partially resolved, the line spacing being about 1.47 cm—1 in agreement with predictions based upon electron diffraction measurements. The fine structure of the B1 bands has not been observed (the predicted spacing is 0.5 cm—1) but the interval between maxima of the P and R branches is approximately 26 cm—1 as expected. With 24 cm‐atmospheres of gas no bands were observed between 15μ and 35μ, although the symmetrical C☒C deformation might be expected to produce a band of appreciable intensity within these limits. This frequency has apparently been observed in Raman spectra at 375 cm—1.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70815/2/JCPSA6-9-7-487-1.pd

Adhesive transfer operates during galling

In order to reduce cobalt within the primary circuit of pressurised water reactors (PWR’s), wear-resistant steels are being researched and developed. In particular interest is the understanding of galling mechanisms, an adhesive wear mechanism which is particularly prevalent in PWR valves. Here we show that large shear stresses and adhesive transfer occur during galling by exploiting the 2 wt.% manganese difference between 304L and 316L stainless steels, even at relatively low compressive stresses of 50MPa. Through these findings, the galling mechanisms of stainless steels can be better understood, which may help with the development of galling resistant stainless steels

A comparison of the galling wear behaviour of PVD Cr and electroplated hard Cr thin films

Electroplated hard chromium (EPHC) is used in many industries as a wear and corrosion resistant coating. However, the long term viability of the electroplating process is at risk due to legislation regarding the toxic chemicals used. The physical vapour deposition (PVD) process has been shown to produce chromium and chromium-based coatings that could be a possible alternative for EPHC in some applications. This study investigates the microstructure and properties of two PVD chromium coatings as a possible alternative to EPHC to provide resistance to galling. Two PVD deposition processes are investigated, namely electron beam PVD (EBPVD) and unbalanced magnetron sputtering (UMS). Galling wear tests were performed according to ASTM G98-17. The results show that the two PVD coatings are of similar hardness, surface roughness and exhibit similar scratch behaviour. However, the galling wear resistance of the coating deposited by UMS is approximately ten times that of the EBPVD coating, and similar to that of the EPHC. X-ray diffraction reveals that the EBPVD chromium coating has a strong preferred orientation of the {200} planes parallel to the coating surface whilst in the UMS PVD coating, preferred orientations of the {110} and {211} planes parallel to the surface are observed. The EPHC does not exhibit relative peak intensities which conform to the International Centre for Diffraction Data (ICDD) powder diffraction pattern consistent with chromium. The crystal orientation of the PVD chromium coatings appears to play a significant role in influencing galling resistance