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Thermophysical Properties: Viscosity, Density, and Excess properties of 2-propanol and n-Decane mixtures from 283.15 K to 343.15 K under atmospheric conditions
No full textInternational audienceTo study the effects of temperature as well as molecular interaction of a fluid system on the thermophysical properties of 2-propanol and n-Decane binary mixture, the density (ρ), dynamic viscosity (η), speed of sound (), and refractive index () of pure 2-propanol and n-Decane, along with their binary mixtures, were experimentally measured across the entire compositional range at temperatures from 283.15 to 343.15 K and atmospheric pressure. These experimental measurements helped in the evaluation of various thermophysical properties, such as excess molar volume , coefficient of thermal expansion (), and isentropic compressibility . The experimental dynamic viscosity (η) and density (ρ) data were used to evaluate kinematic viscosity (v) and Gibbs free energy (ΔG) of flow with an equation based on Eyring's absolute state theory, and their corresponding excess properties. The excess properties of the binary mixtures were correlated using a Redlich-Kister type polynomial equation via the least-squares regression method, with fitting parameters determined for the binary system. Moreover, the Prigogine–Flory–Patterson theory (PFP) was utilized to identify the primary molecular interactions contributing to the excess molar volume at 293.15, 308.15, and 323.15 K for the binary mixtures. Additionally, the capability of the Eyring-NRTL model was tested to predict the viscosity as well as vapor-liquid equilibrium (VLE) of the binary system, and the correlated model results agreed with literature data
Scripts II: Le cogito des multiplicités
No full textInternational audienceCet ouvrage est un lieu de multiplicités philosophiques. Qu'est-ce qui les tient ensemble? Une fidélité, à la philosophie sans doute, une fidélité au réel surtout. Contempler les philosophies dans leur multiplicité change l'écriture philosophique. La multiplicité fonctionne comme une plateforme, voire un ensemble de plateformes superposées, où il est possible d'extraire des fragments à recomposer autrement. Les concepts sont les voyageurs entre les plateformes et charrient des extraits qui s'adaptent graduellement à leur nouveau lieu
Effect of crystal orientation on recrystallization occurrence in CMSX-4
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Investigating the influence of strain rate on hydrogen embrittlement in steel sub-size tensile specimens using 3D X-ray tomography
No full textInternational audienceThis study investigates the effect of strain rate on hydrogen embrittlement in ferritic-pearlitic E355 steel subsize tensile specimens. Micrometer-scale damage analysis was performed using 3D X-ray tomography. Tests were conducted using an optical extensometry at varying strain rates in air and a 100 bar gas hydrogen atmosphere, including interrupted tests before rupture to capture damage states. Hydrogen reduces ductility, with losses reaching up to 62.8% at slower strain rates. At moderate strain rate, 5 × 10-4 s-1, surface damage manifests as brittle, flat ellipsoidal cracks perpendicular to the tensile axis, while the bulk retains ductile damage with prolate voids aligned longitudinally. Hydrogen-enhanced internal shearing leads to damage coalescence via slant fracture of the ligament between surface cracks and internal voids. At low strain rates (1 × 10-5 s-1), deeper hydrogen diffusion induces brittle flat ellipsoidal cracks both at the surface and in the bulk
Paléohydrologie périglaciaire du Pléistocène reconstituée à partir des morphologies des grès du Bassin de Paris, France
No full textInternational audienceAbstract A model for groundwater silicification within the Sables de Fontainebleau in sub-contemporary landscapes in the Paris Basin proposed 35 years ago has since been continuously and substantially updated, particularly with reference to new studies that relate silica precipitation to periglacial climate conditions. Herein we link the various distinctive morphologies of silicified sandstone bodies to the flow paths of groundwaters that imported the silica, the conditions under which it was precipitated, and the patterns of iced ground. The silicified masses are, in a way, fossil groundwater flow paths. The spatial arrangements of these paleo-groundwater flow paths suggest that permafrost developed to significant depth in parts of the Paris Basin. Our model visualizes a gradual settlement of periglacial conditions in the landscape starting with (1) cooling of the near-surface regolith and development of horizontal silicified pans; (2) progressive descent of impermeable permafrost as glacial conditions persisted, leading to non-horizontal flows ‘forced’ beneath the frozen layer; (3) thickening of the permafrost and consequent pressurization of groundwater in the phreatic zone when groundwater outflows to the valleys froze and closed, and convoluted silicified masses and possibly vertical dikes were formed; (4) followed by later thawing of the permafrost and a reduction in hydrostatic level due to climate warming leading to growth of geotropic silicified bodies when residual permafrost remained at depth. In this context, the distinctive morphologies of the silicified sand masses are proxies for the paleohydrology that prevailed during silicification and constitute a new toolbox for determining the depths reached by permafrost at time of silicification.Le modèle d’une silicification de nappe, liée aux paysages subactuels, proposé il y a 35 ans, a été précisé depuis et complété avec l’introduction des climats périglaciaires qui expliquent la précipitation de la silice. Ici nous présentons des morphologies des corps silicifiés qui caractérisent les chemins d'écoulement des eaux de nappe qui ont importé la silice et qui sont en quelque sorte des chemins d'écoulement fossilisés par les grès. Nos observations étayent la présence d’un pergélisol (ou permafrost) profond dans le bassin de Paris pendant les glaciations quaternaires et qui permettent de remontrer à l’hydrologie de ces paléopaysages
Managing skills of craftsmen within the industrialization of large manufacturers: the strategic balance between production know-how and repair expertise
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Reproductive Factors, Sex Hormone Levels, and Differentiated Thyroid Cancer Risk : A Mendelian Randomization Study
No full textInternational audienceBackground : Differentiated thyroid carcinoma (DTC) is occurring three times more frequently in females than in males. However, the underlying biological mechanisms driving this discrepancy remain poorly understood. To investigate the causal role of sex hormones and reproductive factors in the risk of DTC, we implemented a two-sample Mendelian randomization (MR) analysis. Methods : We utilized genome-wide association studies (GWAS) summary statistics to explore these associations. GWAS data on DTC were derived from a meta-analysis of six studies including 7705 cases and 963,612 controls of European ancestry. GWAS summary statistics on sex hormones, reproductive factors, and gynecological conditions were retrieved from publicly available sources. We used the inverse-variance weighted (IVW) method to estimate odds ratio (OR), with additional sensitivity analyses and conducted multivariable MR (MVMR) to account for potential confounding by body mass index (BMI) and thyrotropin (TSH). Results : We identified a positive association between sex hormone binding globulin (SHBG) and DTC (ORivw = 1.13, p = 0.046). After controlling for TSH and BMI in a MVMR analysis, the strength of this association remained similar but lost statistical significance. Bioavailable testosterone also showed a positive but marginally significant association with DTC after adjustment for BMI in the MVMR (ORivw = 1.13, p = 0.07). Putative causal association was observed with uterine fibroids in females under 50 years old (ORivw = 1.52, p = 0.017). Endometrial cancer was associated with DTC (ORivw = 1.15, p = 9.0 × 10−3); however, a genetic correlation of r2 = 13% suggested potential pleiotropy. No significant associations were observed for other investigated factors. Conclusions : Our study does not provide strong evidence for a causal role of reproductive and hormonal factors in DTC risk, despite the observed sex disparity in incidence rates. The associations observed with SHBG, bioavailable testosterone, uterine fibroids, and endometrial cancer indicate potential risk factors, but further investigation is required
A new generation zero-dimensional physics-based model for proton-exchange membrane fuel cells
No full textInternational audienceFinding a good trade-off between accuracy and complexity, computational cost of physics-based models of proton-exchange membrane fuel cells is not an easy task. Relatively simple zero-dimensional (0D) models allow for fast simulation and integration in more complex system-level models. On the downside, sensitivity to varying operating conditions is not necessarily well captured, especially for strong current densities where liquid water, gas transport resistance and temperature gradients may be present. Therefore, the current trend in the literature is towards more complex models going from 1D+1D to 3D models, where full transport equations are solved, at the expense of a high computational cost and an impressive list of required input parameters (not always readily available) [1]. Except for a few works, such as the ones from Ritzberger et al. [2] or Schröder et al. [3], not much effort has been addressed at developing performant 0D models since the foundation works of early 2000s. Here we propose a new generation physics-based PEM fuel cell 0D model which consider recent insights gained from experimental work on oxygen transport resistance [4,5] and catalyst layer proton resistance [6], ionomer thin-film properties [7] and platinum oxidation [8]. An analytical solution for water transport in the PFSA membrane developed by Ferrara et al. [9] is also included. A first validation of the model against experimental data and model results from Gass et al. [10] and Goshtasbi et al. [11] is presented, which shows that the model captures well the impact of varying operating conditions
Bayesian reconstruction of anisotropic flow fluctuations at fixed impact parameter
No full textInternational audienceThe cumulants of the distribution of anisotropic flow are measured accurately in Pb+Pb collisions at the LHC as a function of centrality classifiers (charged multiplicity and/or transverse energy). Using Bayesian inference, we reconstruct from these measurements the probability distribution of anisotropic flow in the ``theorists' frame'' where the impact parameter has a fixed magnitude and orientation, up to centrality. The variation of flow fluctuations with impact parameter displays direct evidence of viscous damping, which is larger for higher Fourier harmonics, in line with expectations from hydrodynamics. We use intensive measures of non-Gaussian flow fluctuations, which have reduced dependence on centrality. We infer from ATLAS data the magnitude of these intensive non-Gaussianities in each Fourier harmonic. They provide data-driven estimates of response coefficients to initial anisotropies, without resorting to any specific microscopic model of initial conditions. These estimates agree with viscous hydrodynamic calculations