Refus de l’action <i>ut singuli</i> au bénéfice des membres d’association… Il est temps de légiférer !

Id : BJS202b9. Réf : BJS juin 2023, n° BJS202b9International audienceConfirmant une jurisprudence contestée, cette récente réponse ministérielle rappelle l’impossibilité pour les adhérents d’une association d’exercer l’action ut singuli afin de contraindre leurs dirigeants fautifs à réparer le préjudice causé au groupement.Rép. min. n° 05335, 2 mars 2023,JO Sénat, 2 mars 2023, p. 1582, C. Dumas.I – La faiblesse des argumentsII – Une évolution nécessaire

Étude expérimentale de la relation entre rhéologie et structure de copolymères à blocs à base d acrylate. (Apport pour la formulation des autoadhésifs.)

Afin d étudier l effet de la structuration des copolymères à blocs sur leurs propriétés viscoélastiques et de proposer de nouvelles solutions de formulations autoadhésives, des copolymères di- et triblocs composés majoritairement de poly(acrylate de n-butyle) (PnBA) et de bloc(s) de polystyrène ont été synthétisés par polymérisation radicalaire contrôlée. Nous avons montré que la ségrégation des blocs est difficile à obtenir de part la faible valeur du paramètre d interaction de Flory-Huggins du couple PS/PnBA. Néanmoins, quand celle-ci est effective, différentes morphologies ont pu être observées (bicontinues, cylindriques, sphériques) et dont la nature est dépendante de la masse moléculaire, de la composition et de la polymolécularité (Ip). De plus, nous avons observé que la morphologie a une influence importante sur le comportement viscoélastique de ces matériaux. En particulier, nous avons pu démontrer qu il existe des valeurs limites en termes de masses et d Ip afin que le comportement viscoélastique de ces matériaux soit adéquat pour leur utilisation dans des formulations autoadhésives. Ces limites étant difficiles à mettre en oeuvre industriellement, nous avons proposé des solutions originales pour palier à ces difficultés (substitution du PS par du PMMA, ajout d homopolymère de PnBA). De plus, l étude d une série homologue d homopolymères de PnBA a permis la modélisation de leurs propriétés rhéologiques et de celles des copolymères à blocs. Finalement, les propriétés d adhérence de formulations fabriquées à partir de ces copolymères ont été analysées et comparées à celles d une formulation commerciale en corrélation avec leurs propriétés viscoélastiques.In this work, we studied the effect of nanostructure of block copolymers on their rheological behaviour and proposed new solutions for self-adhesive formulations. Thereby, we synthesized by controlled radical polymerization di- and triblock soft copolymers composed of poly(n-butyl acrylate) (PnBA) and polystyrene. The segregation of these materials is very difficult to obtain due to the low value of the PnBA/PS Flory-Huggins interaction parameter. However, when the segregation is effective, bicontinuous, cylindrical and spherical morphologies are observed depending on the molecular mass, the composition and the polydispersity index (PDI). Moreover, these morphologies greatly influence the viscoelastic behaviour of these materials. In particular, we demonstrate the existence of limit values concerning the molecular mass and the PDI of these materials in obtaining appropriate viscoelastic properties for applications in self-adhesives formulations. Given that, these limits are very difficult to achieve in an industrial context, we propose alternate solutions such as substituting the PS blocks by poly(methyl methacrylate) or adding PnBA homopolymers. In order to model the rheological behaviour of these block copolymers, a series of analogous PnBA homopolymers were prepared and studied. Finally, the adherence properties of block copolymers based formulations are analyzed and compared with those of a commercial formulation with respect to their viscoelastic properties.PAU-BU Sciences (644452103) / SudocSudocFranceF

Rheological characterization and molecular modeling of poly(n-butyl acrylate)

cited By 4International audienceWe propose an exhaustive experimental characterization of a series of poly(n-butyl acrylate) samples that were synthesized by controlled radical polymerization and have different molecular weights. We focus on the rheological behavior of these polymers and propose a model of their rheological behavior using a molecular model based on the reptation concept. We report the principal rheological parameters for these homopolymers and demonstrate good agreement between model predictions and experimental dat

Model-based fault detection using analytical redundancy for automotive proton exchange membrane fuel cell

International audienceIn this paper, we present a model-based approach for fault detection and isolation of faulty operating conditions of proton exchange membrane fuel cells, and we analyse experimental results of fault detection obtained on a 20 cells fuel cell stack. The system is modelled using MEPHYSTO-FC, a 2D + 0D multi-physics fuel cell model based on lumped and bond-graph approach. Parameters of the model are identified on the 20 cells stack. For the experiments, the fuel cell is operated in nominal condi- tions and in seven different faulty conditions. The model computes the estimated fuel cell voltage and the real part of the high frequency impedance. This model-based estimation is compared to the measured data to generate two residual signals used for the fault detection. The detection algorithm is finally veri- fied during the time evolution of operating conditions, creating faults in the fuel cell and observing the residuals

Fault Detection and Isolation for Proton Exchange Membrane Fuel Cell Using Impedance Measurements and Multiphysics Modeling

International audienceThis study proposes a fault detection and isolation tool for proton exchange membrane fuel cell (PEMFC) operating in embedded applications. A model‐based approach, taking partially into account degradation phenomena, is proposed in order to increase the robustness of the tool regarding transient operations and stack ageing. The considered faults are the abnormal operating conditions that can decrease the fuel cell lifetime. The fault detection approach is based on residual generation using both voltage and high frequency resistance measurements and thus combining the advantages of knowledge‐based model and electrochemical impedance spectroscopy (EIS) diagnosis approaches. To that end, a multi‐physics fuel cell model has been used. This model computes not only the stack voltage but also the high frequency resistance in dynamic conditions. Additionally, the model is modified to take into account the ageing of the fuel cell. Validation is carried out on experimental characterizations during 1,000 h ageing. The results on a new fuel cell stack show a score of 91% for fault isolation. However, without any adaptation, this score drops dramatically as the stack ages. Finally, thanks to ageing modeling and to the proposed adaptation of the detection/isolation procedure, the diagnosis performance remains reliable during fuel cell stack ageing

Procédé de diagnostic d'une pile à combustible

L'invention concerne un procédé de diagnostic d'une pile à combustible (PAC) comprenant les étapes suivantes : Mesure du courant électrique (l_m), de la tension (U_m) aux bornes de la pile à combustible et de l'impédance (ZHF_m) produit par la pile à combustible à un premier instant (T), Estimation dans des conditions normales de fonctionnement, à partir dudit courant mesuré injecté dans un premier modèle simplifié (M1_j) reliant la variation de la tension en fonction du courant et la variation de l'impédance électrique en fonction du courant, d'une tension théorique (U_th_1) audit premier instant et de l'impédance électrique théorique (ZHF_th_1) audit premier instant, Détermination d'un premier résidu (R1) de tension et d'un deuxième résidu d'impédance, Détermination d'au moins un type de défaut à partir d'un deuxième modèle simplifié (M2_j) configuré pour relier les valeurs prises par les deux résidus à un type de défaut

Fluorescent peptide biosensor for probing CDK6 activity in lung cancer cell extracts

International audienceCDK6 kinase regulates cell cycle progression in G1, together with CDK4, but has cell-, tissue- and developmentally-distinct functions associated with transcription, angiogenesis and metabolism. Although CDK6 constitutes an attractive cancer biomarker and target there are no means of assessing its activity in a complex environment. In this study we describe design, engineering and characterization of a fluorescent peptide biosensor derived from 6-phosphofructokinase that reports on CDK6 kinase activity through sensitive changes in fluorescence intensity. This biosensor can report on CDK6 activity in a dose-dependent fashion, thereby enabling quantification of differences in kinase activity in complex and physiologically-relevant environments. Further implementation of this biosensor in different lung and melanoma cell lines, as well as in mesothelioma cell lines derived from patients together with a CDK4 biosensor highlighted differences in kinase activity between CDK6 and CDK4 kinase. This work demonstrates the utility of these selective tools for monitoring two closely related kinases comparatively and simultaneously in the same samples, thereby offering attractive perspectives for diagnostic and therapeutic purposes

A cardiac-specific robotized cellular assay identified families of human ligands as inducers of PGC-1α expression and mitochondrial biogenesis.

Mitochondrial function is dramatically altered in heart failure (HF). This is associated with a decrease in the expression of the transcriptional coactivator PGC-1α, which plays a key role in the coordination of energy metabolism. Identification of compounds able to activate PGC-1α transcription could be of future therapeutic significance.We thus developed a robotized cellular assay to screen molecules in order to identify new activators of PGC-1α in a cardiac-like cell line. This screening assay was based on both the assessment of activity and gene expression of a secreted luciferase under the control of the human PGC-1α promoter, stably expressed in H9c2 cells. We screened part of a library of human endogenous ligands and steroid hormones, B vitamins and fatty acids were identified as activators of PGC-1α expression. The most responsive compounds of these families were then tested for PGC-1α gene expression in adult rat cardiomyocytes. These data highly confirmed the primary screening, and the increase in PGC-1α mRNA correlated with an increase in several downstream markers of mitochondrial biogenesis. Moreover, respiration rates of H9c2 cells treated with these compounds were increased evidencing their effectiveness on mitochondrial biogenesis.Using our cellular reporter assay we could identify three original families, able to activate mitochondrial biogenesis both in cell line and adult cardiomyocytes. This first screening can be extended to chemical libraries in order to increase our knowledge on PGC-1α regulation in the heart and to identify potential therapeutic compounds able to improve mitochondrial function in HF