136 research outputs found

    Mass transfer in a membrane aerated biofilm

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    We present experimental results of mass transfer of a non reactive tracer gas (neon)measured in aerobic heterotrophic biofilm developed from activated sludge. Biofilms are grown in various hydrodynamic conditions and the effective diffusivity is used to quantify the mass transfer through the biofilm. Beyond some cross-flow conditions, the effective diffusivity through the biofilm seems larger than in the bulk. This can be explained by a dispersion generated by convection inside the biofilm, as supported by an analytical flow model and in accordance to the numerical simulation proposed by Aspa et al. (2011)

    Transfert de matière dans un biofilm aéré sur membrane

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    Les réacteurs à biofilm aéré sur membrane sont des procédés innovants de traitement de l'eau. Les substrats nécessaires à la croissance bactérienne sont en contre-diffusion dans le biofilm. Ainsi, pour maitriser la capacité de traitement de ces réacteurs, il est nécessaire de comprendre le transfert de matière dans ces biofilms. Ce travail présente les résultats expérimentaux du transfert de matière mesuré par un traceur non réactif dans des biofilms mixtes hétérotrophes aérobies. Plusieurs conditions hydrodynamiques ont été appliquées pour la croissance des biofilms. La présence de convection dans les canaux de celui-ci a été mise en évidence au-delà d'un Nombre de Peclet de transition. Ensuite, la prise en compte de la convection via le coefficient de diffusivité relative vient compléter le transfert de matière dans les modèles de croissance de biofilm. Les résultats expérimentaux ont montré que la vitesse de consommation de la matière organique augmente avec le Nombre de Reynolds liée à une augmentation de la capacité de transfert des biofilms.Aerated biofilms reactors represent an innovative process to treat water. Substrates required for bacterian growth are in counter-diffusion towards the biofilm. In order to control biological kinetics, it is fundamental to understand mass transfer in these biofilms. This work presents experimental results of a mass transfer measured by a non reactive tracer in mixed aerobic and heterotrophic biofilms. Various hydrodynamic conditions were applied to grow the biofilms. Beyond a Peclet Number of transitions, convection in the channels was observed. Biofilm growth models were then completed taking account this convection via the effective diffusivity coefficient. Experimental results showed that organic mass consumption kinetic grows with the Reynolds Number associated with an increase in the mass transfer capacity of the biofilms

    L'intellect agent et la lumière : évolutions d'une analogie dans le péripatétisme gréco-arabe

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    Lorsque je comprends, je dis « je vois », ou bien « c’est clair » lorsque je suis persuadé d’un contenu. Derrière ces expressions anodines et employées chaque jour se cache une conception antique de l’entendement et une analogie traditionnelle entre le phénomène de la vision et celui de l’intellection. Les philosophies de l’Antiquité, celles de Platon et d’Aristote, ont fait l’objet de ce qu’il est d’usage de nommer la translatio studiorum. Autrement dit, le voyage de ces philosophies par différents territoires et différentes langues, et qui a aboutit à une relecture partielle mais substantielle de chaque corpus. S’il est une notion qui a particulièrement intéressé les philosophes médiévaux, c’est bien celle de l’universel. Comment deux hommes peuvent-ils saisir un même universel tout en conservant leurs facultés propres ? Quel mécanisme universel permet de régir l’intellection humaine

    Interventions to Modify Psychological Well-Being: Progress, Promises, and an Agenda for Future Research

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    Psychological well-being, characterized by feelings, cognitions, and strategies that are associated with positive functioning (including hedonic and eudaimonic well-being), has been linked with better physical health and greater longevity. Importantly, psychological well-being can be strengthened with interventions, providing a strategy for improving population health. But are the effects of well-being interventions meaningful, durable, and scalable enough to improve health at a population-level? To assess this possibility, a cross-disciplinary group of scholars convened to review current knowledge and develop a research agenda. Here we summarize and build on the key insights from this convening, which were: (1) existing interventions should continue to be adapted to achieve a large-enough effect to result in downstream improvements in psychological functioning and health, (2) research should determine the durability of interventions needed to drive population-level and lasting changes, (3) a shift from individual-level care and treatment to a public-health model of population-level prevention is needed and will require new infrastructure that can deliver interventions at scale, (4) interventions should be accessible and effective in racially, ethnically, and geographically diverse samples. A discussion examining the key future research questions follows

    Human Inborn Errors of Immunity : 2022 Update on the Classification from the International Union of Immunological Societies Expert Committee

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    We report the updated classification of inborn errors of immunity, compiled by the International Union of Immunological Societies Expert Committee. This report documents the key clinical and laboratory features of 55 novel monogenic gene defects, and 1 phenocopy due to autoantibodies, that have either been discovered since the previous update (published January 2020) or were characterized earlier but have since been confirmed or expanded in subsequent studies. While variants in additional genes associated with immune diseases have been reported in the literature, this update includes only those that the committee assessed that reached the necessary threshold to represent novel inborn errors of immunity. There are now a total of 485 inborn errors of immunity. These advances in discovering the genetic causes of human immune diseases continue to significantly further our understanding of molecular, cellular, and immunological mechanisms of disease pathogenesis, thereby simultaneously enhancing immunological knowledge and improving patient diagnosis and management. This report is designed to serve as a resource for immunologists and geneticists pursuing the molecular diagnosis of individuals with heritable immunological disorders and for the scientific dissection of cellular and molecular mechanisms underlying monogenic and related human immune diseases.Peer reviewe

    Allosteric Antagonist Modulation of TRPV2 by Piperlongumine Impairs Glioblastoma Progression.

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    The use of computational tools to identify biological targets of natural products with anticancer properties and unknown modes of action is gaining momentum. We employed self-organizing maps to deconvolute the phenotypic effects of piperlongumine (PL) and establish a link to modulation of the human transient receptor potential vanilloid 2 (hTRPV2) channel. The structure of the PL-bound full-length rat TRPV2 channel was determined by cryo-EM. PL binds to a transient allosteric pocket responsible for a new mode of anticancer activity against glioblastoma (GBM) in which hTRPV2 is overexpressed. Calcium imaging experiments revealed the importance of Arg539 and Thr522 residues on the antagonistic effect of PL and calcium influx modulation of the TRPV2 channel. Downregulation of hTRPV2 reduces sensitivity to PL and decreases ROS production. Analysis of GBM patient samples associates hTRPV2 overexpression with tumor grade, disease progression, and poor prognosis. Extensive tumor abrogation and long term survival was achieved in two murine models of orthotopic GBM by formulating PL in an implantable scaffold/hydrogel for sustained local therapy. Furthermore, in primary tumor samples derived from GBM patients, we observed a selective reduction of malignant cells in response to PL ex vivo. Our results establish a broadly applicable strategy, leveraging data-motivated research hypotheses for the discovery of novel means tackling cancer

    OVX033, a nucleocapsid-based vaccine candidate, provides broad-spectrum protection against SARS-CoV-2 variants in a hamster challenge model

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    Spike-based COVID-19 vaccines induce potent neutralizing antibodies but their efficacy against SARS-CoV-2 variants decreases. OVX033 is a recombinant protein composed of the full-length nucleocapsid (N) protein of SARS-CoV-2 genetically fused to oligoDOM®, a self-assembling domain which improves antigen immunogenicity. OVX033 including N as an antigenic target is proposed as new vaccine candidate providing broad-spectrum protection against sarbecoviruses. OVX033 demonstrated its ability to trigger cross-reactive T cell responses and cross-protection against three variants of SARS-CoV-2 (B.1 Europe, Delta B.1.617.2, and Omicron B.1.1.529) in a hamster challenge model, as evidenced by lower weight loss, lower lung viral loads, and reduced lung histopathological lesions
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