CFD Simulations in Mechanically Stirred Tank and Flow Field Analysis: Application to the Wastewater (Sugarcane Vinasse) Anaerobic Digestion

Anaerobic digestion is a widely used process for waste treatment and energy production. This natural process takes place in a controlled environment, anaerobic digesters. Mixing is one of the main operating parameters. The understanding of the flows during the agitation of the medium is crucial for the optimization of the process yield. In fact, the mass and heat transfers are enhanced by the agitation. However, the complex biochemical reactions can be inhibited with overly vigorous agitation. A detailed and in-depth understanding of the phenomena occurring during agitation requires modeling studies. In this chapter, we propose a general approach, based on computational fluid mechanics (CFD), to analyze the mechanical mixing of an anaerobic reactor. We apply this work to the anaerobic digestion of the sugarcane vinasse, which is a liquid waste generated during the production of alcohol. The single-phase Reynolds-averaged Navier-Stokes (RANS) simulations of mechanical agitation of Newtonian fluids for different rotational speeds are presented. The equations system is closed with the standard k-epsilon turbulence model. The flow field is analyzed with the velocity profiles, the Q and Lambda2 fields, the pressure and the vorticity

ERK Is Involved in the Reorganization of Somatosensory Cortical Maps in Adult Rats Submitted to Hindlimb Unloading

Sensorimotor restriction by a 14-day period of hindlimb unloading (HU) in the adult rat induces a reorganization of topographic maps and receptive fields. However, the underlying mechanisms are still unclear. Interest was turned towards a possible implication of intracellular MAPK signaling pathway since Extracellular-signal-Regulated Kinase 1/2 (ERK1/2) is known to play a significant role in the control of synaptic plasticity. In order to better understand the mechanisms underlying cortical plasticity in adult rats submitted to a sensorimotor restriction, we analyzed the time-course of ERK1/2 activation by immunoblot and of cortical reorganization by electrophysiological recordings, on rats submitted to hindlimb unloading over four weeks. Immunohistochemistry analysis provided evidence that ERK1/2 phosphorylation was increased in layer III neurons of the somatosensory cortex. This increase was transient, and parallel to the changes in hindpaw cortical map area (layer IV). By contrast, receptive fields were progressively enlarged from 7 to 28 days of hindlimb unloading. To determine whether ERK1/2 was involved in cortical remapping, we administered a specific ERK1/2 inhibitor (PD-98059) through osmotic mini-pump in rats hindlimb unloaded for 14 days. Results demonstrate that focal inhibition of ERK1/2 pathway prevents cortical reorganization, but had no effect on receptive fields. These results suggest that ERK1/2 plays a role in the induction of cortical plasticity during hindlimb unloading

Impact à moyen terme de l’optimisation de l’infliximab sur la prise en charge chirurgicale des formes sévères des maladies inflammatoires chroniques de l’intestin après trois ans de suivi

Background: severe IBD patients are prone to increased drug clearance via accelerated drug metabolism as well as excess loss through fecal excretion and may require higher doses of infliximab (IFX) to achieve appropriate pharmacokinetics and drug concentrations. Exactly how to optimize accelerated dosing strategies remains an unanswered question. Method: Our aim was to evaluate the efficacy of metaoptimized IFX (MIFX), i.e. combined intensified induction and maintenance regimen as compared to a standard IFX (SIFX) schedule historical cohort on 3-year surgical rates. In this retrospective single center study, two cohorts of patients with CD and UC who were hospitalized at our single teaching hospital for an acute severe flare were identified from 2014 to 2016 (MIFX cohort) and 2007 to 2014 (SIFX cohort) were identified. Severe UC and CD were defined per clinical assessment with a Lichtiger Index > 12 for UC, a Harvey Bradshaw Index (HBI) > 12 for CD and according to ECCO classification. Results: 15/46 (35.6%) MIFX had undergone surgery, against 21/49 (43.8%) in SIFX group, after 3 year of follow up. SIFX patients are 1.6-fold chance of not being surgery-free at 3 year than MIFX patients (OR 1.6 [95% IC: 0.633-4.255], p=0.308). Conclusion: Our study suggests that, in our real-life practice, severe selected IBD patients with IFX metaoptimization had more persistent and higher chance of being surgery-free at the mid-term without carrying an increased risk for infection.Contexte : Les maladies intestinales inflammatoires provoquent des lésions digestives qui peuvent nécessiter une intervention chirurgicale dans les cas graves. Les médicaments anti-TNF réduisent les complications de ces maladies, mais certains patients résistent au traitement. Le but de ce travail était de déterminer si l'optimisation de la dose à 10 mg/kg à la semaine zéro, à la semaine 1 puis à la semaine 4 et ensuite toutes les 4 semaines réduisait la nécessité d'une intervention chirurgicale à moyen terme. Méthode : Étude rétrospective de type avant/après monocentrique, portant sur 96 patients souffrant de DHA grave (dont 62 personnes atteintes de la maladie de Crohn, 33 de colite ulcéreuse). 46 en régime méta-optimisé (MIFX), 49 en régime standard, cohorte historique (SIFX) (5 mg/kg à la semaine 0 ; semaine 2, semaine 6 puis toutes les 8 semaines). Le critère de jugement principal était le taux de chirurgie après 3 ans de suivi. Résultats : 15/46 (35,6%) MIFX ont été opérés, contre 21/49 (43,8%) dans le groupe SIFX, après trois ans de suivi. Les patients du groupe SIFX ont 1,6 fois plus de risque d'être opérés que ceux du groupe MIFX (OR 1,6 [95% IC : 0,633-4,255], p=0,308), mais ce résultat est non significatif. Conclusion : Il s'agit d'une étude encourageante, mais non significative, qui montre que la méta-optimisation pourrait réduire le taux de chirurgie dans les formes graves. Un essai randomisé pourrait être intéressant pour confirmer cette tendance

Molecular and functional characteristics of human vastus lateralis muscle after 5-day dry immersion and countermeasure

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Molecular markers and functional characteristics of human skeletal muscle deconditioning after short-term dry immersion

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Skeletal muscle responses to short term disuse: molecular markers and functional characteristics after dry immersion on humans.

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Phosphorylation/glycosylation states of MLC2 regulatory protein in skeletal muscle in disuse conditions.

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ANAEROBIC DIGESTION OF VINASSE AND CFD MODELLING APPROACH CONTEXT AND OBJECTIVES OF THE WORK

International audienceThe study’s ultimate goal consists of modelling and optimising the co-digestion of particulate substrates like sewage sludge, biowaste and vinasse from sugar cane. Given these substrates, the medium is highly heterogeneous and has particular physical characteristics and behaviour. Moreover, anaerobic digestion could be lead in wet-mode or in dry-mode, thus we want to develop a model valid for both configurations. In this context, the fluid flow modelling is of interest. Indeed, the contact between substrates and microorganisms has a significant influence on the anaerobic digestion process. It is directly correlated to the flow inside the digester. The research question is therefore the following: Is it possible to predict the spread of microorganisms inside the digester for both liquid and solid digestion? In this paper, we present the context of the work and the mathematical model based on Navier-Stokes equations with the Boussinesq approximation. Large-eddy simulation (LES) is used for the turbulence modelling. The sliding mesh method is used to characterise the impeller rotation. In further work, we will present the simulation results validated with the literature data. The differential equations will be solved on OpenFOAM software using the finite volume method. The flow will be simulated for both Newtonian (vinasse) and non-Newtonian fluids (manure) and at different total solid (TS) rates for non-Newtonian fluids. The obtained results will be the velocity and temperature profiles within the digester. It will hence be possible to optimise the process through both the medium physical properties (TS rate and viscosity) and the digester configuration. We will also consider the multiphase flow. Alongside numerical simulations, experiments are carried out on the substrates studied in order to estimate the methane production. In this poster, we present the results of experiments on the vinasse and the development of the CFD model

Anaerobic digestion of vinasse and cfd modelling approach

International audienceThe study's ultimate goal consists of modelling and optimising the co-digestion of particulate substrates like sewage sludge, biowaste and vinasse from sugar cane. Given these substrates, the medium is highly heterogeneous and has particular physical characteristics and behaviour. Moreover, anaerobic digestion could be lead in wet-mode or in dry-mode, thus we want to develop a model valid for both configurations. In this context, the fluid flow modelling is of interest. Indeed, the contact between substrates and microorganisms has a significant influence on the anaerobic digestion process. It is directly correlated to the flow inside the digester. The research question is therefore the following: Is it possible to predict the spread of microorganisms inside the digester for both liquid and solid digestion? In this paper, we present the context of the work and the mathematical model based on Navier-Stokes equations with the Boussinesq approximation. Large-eddy simulation (LES) is used for the turbulence modelling. The sliding mesh method is used to characterise the impeller rotation. In further work, we will present the simulation results validated with the literature data. The differential equations will be solved on OpenFOAM software using the finite volume method. The flow will be simulated for both Newtonian (vinasse) and non-Newtonian fluids (manure) and at different total solid (TS) rates for non-Newtonian fluids. The obtained results will be the velocity and temperature profiles within the digester. It will hence be possible to optimise the process through both the medium physical properties (TS rate and viscosity) and the digester configuration. We will also consider the multiphase flow. Alongside numerical simulations, experiments are carried out on the substrates studied in order to estimate the methane production. In this article, we present the results of experiments on the vinasse and the development of the CFD model

Consequence of a short term deconditioning period in humans on myosin expression and phosphorylation in skeletal muscle.

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