Aspects of drying and cracking of geomaterials in energy applications

Because of common exposure to high temperatures and forced ventilation of geomaterials in energy production and storage, their failure mode often involves intense drying and constrained shrinkage associated cracking. Previous experiments show that drying cracking occurs when the materials are completely saturated, practically simultaneously with the onset of air entry and start of desaturation. The paper reports on the adhesion forces evolving in drying granular clusters and their critical value associated with the first air entry and formation of the drying cracks, as well as a critical saturation for meso-scale evaporating several grain cluster models of different porosities

Properties of pendular liquid bridges determined on Delaunay’s roulettes

This work addresses the study of capillary bridge properties between two grains, with use of recent analytical model, based on solutions of Young-Laplace equation from an inverse problem. A simple explicit criterion allows to classify the profile of capillary bridge as a surface of revolution with constant mean curvature (Delaunay roulette) using its measured geometrical parameters (gorge radius, contact angle, half-filling angle). Necessary data are obtained from experimental tests, realized on liquid bridges between two equal spherical grains. Sequences of images are recorded at several (fixed) volumes of liquid and different separations distances between the spheres (from contact to rupture), in laboratory and in micro-gravity conditions. For each configuration, an exact parametric representation of the meridian is revealed. Mean bridge curvature, internal pressure and intergranular capillary force are also determined

Properties of pendular liquid bridges determined on Delaunay's roulettes

International audienceThis work addresses the study of capillary bridge properties between two grains, with use of recent analytical model, based on solutions of Young-Laplace equation from an inverse problem. A simple explicit criterion allows to classify the profile of capillary bridge as a surface of revolution with constant mean curvature (Delaunay roulette) using its measured geometrical parameters (gorge radius, contact angle, half-filling angle). Necessary data are obtained from experimental tests, realized on liquid bridges between two equal spherical grains. Sequences of images are recorded at several (fixed) volumes of liquid and different separations distances between the spheres (from contact to rupture), in laboratory and in micro-gravity conditions. For each configuration, an exact parametric representation of the meridian is revealed. Mean bridge curvature, internal pressure and intergranular capillary force are also determined

Évolution de la cohésion dans un matériau granulaire : de la capillarité à la cimentation

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Synthesis, Biochemical Characterization, and Theoretical Studies of Novel β‑Keto-enol Pyridine and Furan Derivatives as Potent Antifungal Agents

In the present study, we report the design and synthesis of new derivatives of the β-keto-enol grafted on pyridine and furan moieties (L1−L11). Structures of compounds were fully confirmed by Fourier transform infrared spectroscopy (FT-IR), 1H NMR, 13C NMR, electrospray ionization/liquid chromatography-mass spectrometry (ESI/LC-MS), and elemental analysis. The compounds were screened for antifungal and antibacterial activities (Escherichia coli, Bacillus subtilis, and Micrococcus luteus). In vitro evaluation showed significant fungicidal activity for L1, L4, and L5 against fungal strains (Fusarium oxysporum f.sp albedinis) compared to the reference standard. Especially, the exceptional activity has been demonstrated for L1 with IC50 = 12.83 μg/mL. This compound and the reference benomyl molecule also showed a correlation between experimental antifungal activity and theoretical predictions by Petra/Osiris/Molinspiration POM) calculations and molecular coupling against the Fgb1 protein. The highest inhibition of bacterial growth for L1 is due to its strongest binding to the target protein. This report may stimulate the further synthesis of examples of this substance class for the development of new drugs

Numerical simulation of the quicksand phenomenon by a 3D coupled Discrete Element - Lattice Boltzmann hydromechanical model

International audienceThis paper deals with the numerical simulation of the quicksand phenomenon using a coupled Discrete Elements – Lattice Boltzmann hydromechanical model. After the presentation of the developed numerical model, simulations of ascending fluid flow through granular deposits are performed. The simulations show that the quicksand actually triggers for a hydraulic gradient very close to the critical hydraulic gradient calculated from the global analysis of classical soil mechanics, that is, when the resultant of the applied external pressure balances submerged weight of the deposit. Moreover, they point out that the quicksand phenomenon does not occur only for hydraulic gradients above the critical hydraulic gradient, but also in some cases with slightly lower gradients. In such cases, a more permeable zone is first gradually built at the bottom of the deposit through a grain rearrangement, which increases the hydraulic gradient in the upper zones and triggers the phenomenon