42 research outputs found
Electrochemical characterization of YSZ thick films deposited by dip-coating process
Yttria stabilized zirconia (YSZ, 8% Y2O3) thick films were coated on dense alumina substrates by a dip-coating process. The suspension was obtained by addition of a polymeric matrix in a stable suspension of commercial YSZ (Tosoh) powders dispersed in an azeotropic mixture MEKâEtOH. The suspension composition was improved by the addition of YSZ Tosoh particles encapsulated by zirconium alkoxide sol containing yttrium nitrate which are the precursors of the 8-YSZ oxide. This optimal formulation allowed preparing, via a dip-coating process, thick films which were, after thermal treatment, homogeneous, dense and crack-free. A specific method was performed to measure the electrical conductivity, i.e. to determine the ionic conductivity of the film: it uses the four-point probe technique combined with ac impedance spectroscopy. The good agreement between the classical two-electrode measurements performed on YSZ pellets and the four-electrode ones performed on YSZ films allows concluding that this method is relevant for characterizing the transport properties of thick films
Intermediate temperature SOFC single cell test using Nd1.95NiO4+ÎŽ as cathode
This work deals with SOFC single cell tests using neodymium nickelate Nd1.95NiO4+ÎŽ as cathode material. This MIEC oxide exhibits high values of both surface exchange coefficient (k) and oxygen diffusion coefficient (D*), as well as high electronic conductivity, which result in an enhanced electrochemical activity with respect to classical materials. The SOFC cells were fabricated from an anode-supported electrolyte half-cell provided by InDEC B.V. Corporation, with a 36mmdiameter. The Nd1.95NiO4+ÎŽ cathode was prepared as a two-stage electrode consisting of a thin interlayer of several hundred nanometers covered by a thicker layer of dozens microns. The Nd1.95NiO4+ÎŽ oxide powders were synthesized using different routes in order to reduce the final annealing temperature, and to subsequently obtain submicronic powders. IâV characteristics of the single cells were investigated under hydrogenâair conditions. The power densities versus current densities curves are reported and the results of impedance spectroscopy measurements performed under these operating conditions are discussed
Prediction and experimental evidence of the optimisation of the angular branching process in the thallus growth of Podospora anserina
Based upon apical growth and hyphal branching, the two main processes that
drive the growth pattern of a fungal network, we propose here a two-dimensions
simulation based on a binary-tree modelling allowing us to extract the main
characteristics of a generic thallus growth. In particular, we showed that, in
a homogeneous environment, the fungal growth can be optimized for exploration
and exploitation of its surroundings with a specific angular distribution of
apical branching. Two complementary methods of extracting angle values have
been used to confront the result of the simulation with experimental data
obtained from the thallus growth of the saprophytic filamentous fungus
Podospora anserina. Finally, we propose here a validated model that, while
being computationally low-cost, is powerful enough to test quickly multiple
conditions and constraints. It will allow in future works to deepen the
characterization of the growth dynamic of fungal network, in addition to
laboratory experiments, that could be sometimes expensive, tedious or of
limited scope.Comment: Submitted to Scientific Repor
The GenTree Platform: growth traits and tree-level environmental data in 12 European forest tree species
Background: Progress in the field of evolutionary forest ecology has been hampered by the huge challenge of phenotyping trees across their ranges in their natural environments, and the limitation in high-resolution environmental information.
Findings: The GenTree Platform contains phenotypic and environmental data from 4,959 trees from 12 ecologically and economically important European forest tree species: Abies alba Mill. (silver fir), Betula pendula Roth. (silver birch), Fagus sylvatica L. (European beech), Picea abies (L.) H. Karst (Norway spruce), Pinus cembra L. (Swiss stone pine), Pinus halepensis Mill. (Aleppo pine), Pinus nigra Arnold (European black pine), Pinus pinaster Aiton (maritime pine), Pinus sylvestris L. (Scots pine), Populus nigra L. (European black poplar), Taxus baccata L. (English yew), and Quercus petraea (Matt.) Liebl. (sessile oak). Phenotypic (height, diameter at breast height, crown size, bark thickness, biomass, straightness, forking, branch angle, fructification), regeneration, environmental in situ measurements (soil depth, vegetation cover, competition indices), and environmental modeling data extracted by using bilinear interpolation accounting for surrounding conditions of each tree (precipitation, temperature, insolation, drought indices) were obtained from trees in 194 sites covering the speciesâ geographic ranges and reflecting local environmental gradients.
Conclusion: The GenTree Platform is a new resource for investigating ecological and evolutionary processes in forest trees. The coherent phenotyping and environmental characterization across 12 species in their European ranges allow for a wide range of analyses from forest ecologists, conservationists, and macro-ecologists. Also, the data here presented can be linked to the GenTree Dendroecological collection, the GenTree Leaf Trait collection, and the GenTree Genomic collection presented elsewhere, which together build the largest evolutionary forest ecology data collection available
Between but not within species variation in the distribution of fitness effects
New mutations provide the raw material for evolution and adaptation. The distribution of fitness effects (DFE) describes the spectrum of effects of new mutations that can occur along a genome, and is therefore of vital interest in evolutionary biology. Recent work has uncovered striking similarities in the DFE between closely related species, prompting us to ask whether there is variation in the DFE among populations of the same species, or among species with different degrees of divergence, i.e., whether there is variation in the DFE at different levels of evolution. Using exome capture data from six tree species sampled across Europe we characterised the DFE for multiple species, and for each species, multiple populations, and investigated the factors potentially influencing the DFE, such as demography, population divergence and genetic background. We find statistical support for there being variation in the DFE at the species level, even among relatively closely related species. However, we find very little difference at the population level, suggesting that differences in the DFE are primarily driven by deep features of species biology, and that evolutionarily recent events, such as demographic changes and local adaptation, have little impact
L'amiante (caractéristiques, pathologies ; importance de l'exposition et prévention du risque)
TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF
Le banquet de Pauline Schmitt Pantel: Genre, mĆurs et politique dans l'AntiquitĂ© grecque et romaine
Le banquet de Pauline Schmitt Pantel. Genre, MĆurs et politique dans lâAntiquitĂ© grecque et romaine, Paris, Publications de la Sorbonne
International audienc
Avant-propos
Pauline Schmitt Pantel sur le chantier archĂ©ologique de Moio della Civitella RĂ©unissant chercheurs français et Ă©trangers, jeunes doctorants et professeurs Ă©mĂ©rites, ce volume collectif entend rendre hommage Ă lâĆuvre de Pauline Schmitt, une annĂ©e aprĂšs son dĂ©part en retraite. AprĂšs un premier « banquet » cĂ©lĂ©brĂ© en son honneur, en octobre 2010, nombreux sont ceux, parmi ses Ă©tudiants, ses collĂšgues et ses amis, qui ont en effet tenu Ă lui offrir une contribution originale. Ă nâen pas douter, ..
Le banquet de Pauline Schmitt
Historienne et enseignante du monde grec, Pauline Schmitt Pantel a incontestablement marquĂ© plusieurs gĂ©nĂ©rations de chercheurs et de chercheuses, tout en sâadressant Ă un large public intĂ©ressĂ© par la GrĂšce antique. Au fil des annĂ©es, elle a contribuĂ© non seulement Ă renouveler des thĂ©matiques classiques en histoire politique, sociale et religieuse, mais aussi Ă dĂ©fricher de nouveaux champs de recherche comme lâhistoire des femmes et du genre. Depuis sa thĂšse dâĂtat sur La CitĂ© au banquet, qui Ă©leva le repas commun au rang de « fait social total », jusquâĂ son tout rĂ©cent ouvrage sur les Hommes illustres de Plutarque, qui bouleverse bien des certitudes sur lâidentitĂ© politique dans lâAthĂšnes classique, en passant par Aithra et Pandora, oĂč elle se penche sur la construction sociale du fĂ©minin et du masculin, lâhistorienne a soumis de nombreux domaines Ă sa volontĂ© de savoir et dâinterroger pratiques et discours grecs, en croisant sources littĂ©raires, Ă©pigraphiques et iconographiques. Ses collĂšgues et amis, français et Ă©trangers, ainsi que ses Ă©tudiants ont ressenti lâenvie et le besoin dâoffrir un banquet dâhommages Ă Pauline Schmitt Pantel, qui a su faire vivre et dĂ©fendre avec dĂ©termination les pratiques de sociabilitĂ© comme lieu dâĂ©change, de collaboration, de formation et dâexpĂ©rimentation du politique, aussi bien dans les citĂ©s grecques que dans lâĂ©quipe de recherche en histoire ancienne quâelle a contribuĂ© Ă fonder dans les universitĂ©s Paris 1 et Paris 7, PhĂ©acie, dĂ©sormais intĂ©grĂ©e dans le centre de recherches Anhima