Can one hear the shape of a saturation patch?

The theory of the acoustics of patchy-saturation in porous media is used to analyze experimental data on wave velocity and attenuation in partially water saturated limestones. It is demonstrated that the theory can be used to deduce the value of V/A, the ratio of the volume to area of the water patch, and l_f, the Poisson size of the water patch. One can ``hear'' the shape of a patch if the properties of the rock and the measurement frequencies are such as to satisfy the specific requirements for the validity of the theory

Mercury iodide nucleation and crystal growth in vapor phase (4-IML-1)

The objectives of this experiment are to grow simultaneously three single crystals of mercuric iodide (HgI2) in an imposed temperature profile and to assess the advantages of growth in microgravity on the HgI2 crystal quality. Growth in microgravity should reduce fluctuations in HgI2 concentrations and thus decrease the resultant crystal defects. In order to test this hypothesis, a seeded growth of HgI2 crystals will be performed on International Microgravity Lab. (IML-1)

Multifluid eulerian modelling of a silicon fluidized bed chemical vapor deposition process : analysis of various kinetic models

Using the multifluid Eulerian code MFIX, the silicon Fluidized Bed Chemical Vapor Deposition process from silane (SiH4) has been modelled under transient conditions. In order to constitute an experimental database, a preliminary experimental study has been performed using a bed of Geldart’s group B particles. After a detailed analysis and comparison of the kinetic models available in the literature, four of them have been implemented in the MFIX code and two hydrodynamic models have been tested. 3-D simulations have shown that a strong interaction exists between the bed hydrodynamics, heat and reactive mass transfers and that Si deposition from silane mainly occurs in the dense zones of the bed whereas the unsaturated species silylene (SiH2) forms in bubbles and slugs and leads to Si deposition mainly at their periphery; its contribution to deposition can be locally as high as that of SiH4. The average contribution of SiH2 to deposition increases with the inlet concentration of silane and can reach 30%. The kinetic models derived from the law of Furusawa et al. and from the data compiled by Buss et al. and the hydrodynamic model based on the true granular energy equation and the Princeton solid phase stress model have revealed to be the most appropriate ones for the conditions tested

Characterization of sulfur distribution in Ni-based superalloy and thermal barrier coatings after high temperature oxidation: a SIMS analysis

Sulfur segregation was characterized by secondary ion mass spectrometry (SIMS) in uncoated single-crystal Ni-based AM1 superalloys with various S contents and on NiPtAl, NiAl and NiPt bondcoats of complete TBC systems. In spite of technical difficulties associated with diffuse sputtered interfaces, an original sample preparation technique and a careful choice of analysis conditions enabled a chemical characterization of S distribution below metal/oxide interfaces. An initial heterogeneous distribution of S in as-received high S (3.2 ppmw) AM1 was measured. After oxidation, a S depletion profile formed, with a slope that depended on the initial bulk S content. GDMS measurements enabled a quantitative distribution of S in oxidized low S (0.14 ppmw) AM1 to be constructed and discussed in relation to equilibrium surface segregation of S on Ni. The quantity of S integrated in the thermally grown oxide (TGO) was estimated and found to be very similar to that measured from depletion found in the metal. Localized S enrichments in Pt-containing coatings are related to a possible beneficial trapping mechanism of Pt on the adherence of oxide scales

La nature de la parenté

La vielle question des liens entre nature et culture s'apparente à un serpent de mer: elle disparaît et resurgit sans fin. Ainsi, en est-il de la question de la parenté. Si la mère n'est pas toujours la femme qui accouche, comment se construit la filiation et comment désigner tous les personnages de la parenté? Que nous dit l'ordre familial d'aujourd'hui sur ces questions? Je ne prétendrais pas y répondre, mais me propose seulment de mettre à plat les situations familiales actuelles- à partir principalment de l'exemple français- pour éclairer la manière dont elles se posent et espérer ainsi mettre une petite pierre sur le chemin d'une réponse. Nous constatons que les nouvelles configurations familiales subissent encore dans leur construction, le poids du modèle familial de référence d'un seul père et d'une seule mère, parents et géniteurs de leurs enfants, alors qu'elles se conjuguent bien mal avec ce modèle. J'essaierai de m'interroger sur ce poids. Puis, alors que la petite histoire du recours à un tiers dans l'établissement de la filiation se complexifie, je me pencherai sur l'établissement de la filiation dans les situations d'adoption et de nouvelles techniques de Reproduction (NTR

Les « faiseurs de parenté » : Un organisme autorisé pour l’adoption

Les « faiseurs de parenté » : un organisme autorisé pour l’adoption (note de recherche)Tout d’abord, je situerai la notion d’intérêt de l’enfant dans le champ de l’adoption dans la perspective ouverte par les travaux de Nadine Lefaucheur quant au moindre mal dans la prise en charge de l’enfant illégitime. Puis je regarderai la manière avec laquelle un organisme agréé pour l’adoption réfléchit afin d’éviter les dérives de l’adoption internationale et d’organiser son activité autour de l’adoption d’enfants difficiles à placer (plus âgés, handicapés, fratries), en accompagnant la famille adoptive dans tout son parcours d’adoption.Accredited Adoption Organizations as “Makers of Parenthood” (Research Note)I am situating my research on adoption according to Nadine Lefaucheur’s notion of the minimization of harm/the lesser evil when dealing with illegitimate children. Also, I am looking at the way in which one accredited adoption organization saw its mandate, choosing to arrange its practice around difficult to place children (older children, children with disabilities, siblings), and accompanying the families throughout the whole adoption process.Los « fabricantes de parentesco » : un organismo autorizado en adopción (nota de investigación)En primer lugar, situaré la noción de interés del niño en el campo de la adopción en la perspectiva abierta en los trabajos de Nadine Lefaucheur respecto al mínimo de inconvenientes en hacerse cargo del niño ilegítimo. Después, consideraré la manera de reflexionar de un organismo autorizado en la adopción con el fin de evitar las derivas de la adopción internacional y organizar su actividad en torno a la adopción de niños difíciles de adoptar (más grandes, minusválidos, hermanos) acompañando a la familia adoptiva a lo largo de su trayectoria de adopción

Chemical Vapor Deposition of silicon nanodots on TiO2 submicronic powders in vibrated fluidized bed

Silicon nanodots have been deposited on TiO2 submicronic powders in a vibrated Fluidized Bed Chemical Vapor Deposition (FBCVD) reactor from silane SiH4. Deposition conditions involving very low deposition rates have been studied. After treatment, powders are under the form of micronic agglomerates. In the operating range tested, this agglomerates formation mainly depends on the fluidization conditions and not on the CVD parameters. The best results have been obtained for anatase TiO2 powders for which the conditions of fluidization have been the most optimized. For these anatase powders, agglomerates are porous. SEM and TEM imaging prove that silicon nanodots (8-10 nm in size) have been deposited on the surface of particles and that this deposition is uniform on the whole powders and conformal around each grain, even if not fully continuous. Raman spectroscopy shows that the TiO2 powders have been partially reduced into TiO2-x during deposition. The TiO2 stoichiometry can be recovered by annealing under air, and IR spectroscopy indicates that the deposited silicon nanodots have been at least partly oxidized into SiO2 after this annealing