Influence of constructive options on the vibro-acoustic behavior of a wooden lightweight structure

This paper aims to present the influence of several constructive options on the vibro-acoustic behavior of a wooden lightweight structure. The experiemental protocol, which was optimised and described in an preceeding paper, allows us to quantify the influence of these constructive options in terms of acoustic level and isolation, eigenfrequencies and vibration mode shapes of the different parts of the structure. The results of this work are coherent and confirmed that the experimental test protocol is functional and repeatable

Interleukin-13 immune gene therapy prevents CNS inflammation and demyelination via alternative activation of microglia and macrophages

Detrimental inflammatory responses in the central nervous system are a hallmark of various brain injuries and diseases. With this study we provide evidence that lentiviral vector-mediated expression of the immune-modulating cytokine interleukin 13 (IL-13) induces an alternative activation program in both microglia and macrophages conferring protection against severe oligodendrocyte loss and demyelination in the cuprizone mouse model for multiple sclerosis (MS). First, IL-13 mediated modulation of cuprizone induced lesions was monitored using T2-weighted magnetic resonance imaging and magnetization transfer imaging, and further correlated with quantitative histological analyses for inflammatory cell influx, oligodendrocyte death, and demyelination. Second, following IL-13 immune gene therapy in cuprizone-treated eGFP+ bone marrow chimeric mice, we provide evidence that IL-13 directs the polarization of both brain-resident microglia and infiltrating macrophages towards an alternatively activated phenotype, thereby promoting the conversion of a pro-inflammatory environment toward an anti-inflammatory environment, as further evidenced by gene expression analyses. Finally, we show that IL-13 immune gene therapy is also able to limit lesion severity in a pre-existing inflammatory environment. In conclusion, these results highlight the potential of IL-13 to modulate microglia/macrophage responses and to improve disease outcome in a mouse model for MS

Influence of the junctions on the vibro-acoustic behaviour of wooden lightweight structures

La forte sensibilité des ouvrages bois aux transmissions latérales, vibrations et autres sons basses fréquences représente un obstacle à leur développement. En réponse à cette problématique, le projet Vibracoubois, dans lequel s'inscrivent ces travaux, vise à développer la caractérisation ainsi que la modélisation des transferts vibro-acoustiques au sein de ces structures. L'objectif principal de ces travaux est donc d'élargir le champ de l'étude expérimentale et numérique à une structure complète constituée de différentes parois et de cavités couplées. Les jonctions, véritables nœuds des systèmes constructifs, sont placées au centre de l'étude. Pour ce faire, un protocole expérimental est développé, permettant d'effectuer des mesures en laboratoire mais également in-situ sur des structures réelles. Les résultats de campagnes d'essais effectuées au sein de deux maquettes d'ouvrages bois (ossature et bois massif) grandeur nature sont présentés. Par ailleurs, en vue de se rapprocher des jonctions réelles du bâtiment, des méthodes numériques de couplage incluant des effets locaux de dissipation sont développées. Une méthode hybride est présentée. Un modèle numérique de la maquette en bois massif, basé sur la méthode des éléments-finis, est créé. L'utilisation de cette méthode est justifiée de par la prépondérance des comportements modaux aux basses fréquences. Ce modèle intègre la méthode hybride en vue d'obtenir un couplage souple entre les parois, par opposition au couplage classique rigide des éléments-finis. Les résultats d'un processus de recalage portant sur les propriétés des parois et des jonctions ainsi que sur le couplage vibro-acoustique sont présentés.Wooden buildings are very sensitive to flanking transmissions, vibrations and low frequency sounds, which interferes with their development. The Vibracoubois project, in which this research work is part of, aims to respond to this problem by improving the vibro-acoustic transfers characterization and modelling of these structures. This research work mainly focuses on expanding the experimental and the numerical scope of the study to an entire structure made of coupled walls and air cavities. The junctions, considered critical for the vibration propagation in these buildings, are placed at the center of this work. First, an experimental protocol is presented. It allows to measure both the vibro-acoustic behaviour of laboratory and real structures. The results of test campaigns run on two full-scale experimental mock-ups (timber frame and CLT) are then presented. Secondly, numerical coupling methods that include local dissipation effects are developed, in order to get closer to real junctions behaviour. A hybrid coupling method is presented. A numerical model of the CLT mock-up, based on the finite-elements method, is then created. The use of this method is justified because of the strong modal behaviour of these structures at low frequencies. This model implements the hybrid coupling method in order to create flexible junctions, as opposed to the classic rigid coupling of the finite-elements. Based on the CLT mock-up experimental measurements, the results of an adjustment process of the wall and the junction properties used in the numerical model is finally presented

Influence des jonctions sur le comportement vibro-acoustique d'assemblages de structures bois pour le bâtiment

Wooden buildings are very sensitive to flanking transmissions, vibrations and low frequency sounds, which interferes with their development. The Vibracoubois project, in which this research work is part of, aims to respond to this problem by improving the vibro-acoustic transfers characterization and modelling of these structures. This research work mainly focuses on expanding the experimental and the numerical scope of the study to an entire structure made of coupled walls and air cavities. The junctions, considered critical for the vibration propagation in these buildings, are placed at the center of this work. First, an experimental protocol is presented. It allows to measure both the vibro-acoustic behaviour of laboratory and real structures. The results of test campaigns run on two full-scale experimental mock-ups (timber frame and CLT) are then presented. Secondly, numerical coupling methods that include local dissipation effects are developed, in order to get closer to real junctions behaviour. A hybrid coupling method is presented. A numerical model of the CLT mock-up, based on the finite-elements method, is then created. The use of this method is justified because of the strong modal behaviour of these structures at low frequencies. This model implements the hybrid coupling method in order to create flexible junctions, as opposed to the classic rigid coupling of the finite-elements. Based on the CLT mock-up experimental measurements, the results of an adjustment process of the wall and the junction properties used in the numerical model is finally presented.La forte sensibilité des ouvrages bois aux transmissions latérales, vibrations et autres sons basses fréquences représente un obstacle à leur développement. En réponse à cette problématique, le projet Vibracoubois, dans lequel s'inscrivent ces travaux, vise à développer la caractérisation ainsi que la modélisation des transferts vibro-acoustiques au sein de ces structures. L'objectif principal de ces travaux est donc d'élargir le champ de l'étude expérimentale et numérique à une structure complète constituée de différentes parois et de cavités couplées. Les jonctions, véritables nœuds des systèmes constructifs, sont placées au centre de l'étude. Pour ce faire, un protocole expérimental est développé, permettant d'effectuer des mesures en laboratoire mais également in-situ sur des structures réelles. Les résultats de campagnes d'essais effectuées au sein de deux maquettes d'ouvrages bois (ossature et bois massif) grandeur nature sont présentés. Par ailleurs, en vue de se rapprocher des jonctions réelles du bâtiment, des méthodes numériques de couplage incluant des effets locaux de dissipation sont développées. Une méthode hybride est présentée. Un modèle numérique de la maquette en bois massif, basé sur la méthode des éléments-finis, est créé. L'utilisation de cette méthode est justifiée de par la prépondérance des comportements modaux aux basses fréquences. Ce modèle intègre la méthode hybride en vue d'obtenir un couplage souple entre les parois, par opposition au couplage classique rigide des éléments-finis. Les résultats d'un processus de recalage portant sur les propriétés des parois et des jonctions ainsi que sur le couplage vibro-acoustique sont présentés

Prévision et mesures vibro-acoustiques dans les bâtiments bois

International audienc

Prévision et mesures vibro-acoustiques dans les bâtiments bois

International audienc

Bacterial protein signals are associated with Crohn's disease

Objective No Crohn’s disease (CD) molecular maker has advanced to clinical use, and independent lines of evidence support a central role of the gut microbial community in CD. Here we explore the feasibility of extracting bacterial protein signals relevant to CD, by interrogating myriads of intestinal bacterial proteomes from a small number of patients and healthy controls. Design We first developed and validated a workflow—including extraction of microbial communities, two-dimensional difference gel electrophoresis (2D-DIGE), and LC-MS/MS—to discover protein signals from CD-associated gut microbial communities. Then we used selected reaction monitoring (SRM) to confirm a set of candidates. In parallel, we used 16S rRNA gene sequencing for an integrated analysis of gut ecosystem structure and functions. Results Our 2D-DIGE-based discovery approach revealed an imbalance of intestinal bacterial functions in CD. Many proteins, largely derived from Bacteroides species, were over-represented, while under-represented proteins were mostly from Firmicutes and some Prevotella members. Most overabundant proteins could be confirmed using SRM. They correspond to functions allowing opportunistic pathogens to colonise the mucus layers, breach the host barriers and invade the mucosae, which could still be aggravated by decreased host-derived pancreatic zymogen granule membrane protein GP2 in CD patients. Moreover, although the abundance of most protein groups reflected that of related bacterial populations, we found a specific independent regulation of bacteria-derived cell envelope proteins. Conclusions This study provides the first evidence that quantifiable bacterial protein signals are associated with CD, which can have a profound impact on future molecular diagnosis

Development Of Micro-Magnets For The Electromagnetic Transduction Of MEMS

International audienceThis paper presents a new class of high-performance permanent micro-magnets based on the controlled assembly of cobalt nanorods for the electromagnetic transduction of MEMS. Micromagnets are fabricated using a low temperature fabrication process that yields a dense material exhibiting high coercive field and remanence to saturation magnetization ratio. The cartography of the magnetic induction produced by the sub-millimeter size magnets was obtained using a scanning Hall effect micro-probe microscope. Silicon microcantilevers placed in the vicinity of these magnets were successfully actuated using the Lorentz force with low currents. The good signal to noise ratio measured at resonance demonstrates the potentiality of these nanostructured micro-magnets

Magnetophoresis-Assisted Capillary Assembly: A Versatile Approach for Fabricating Tailored 3D Magnetic Supercrystals

International audienceThe fabrication and integration of sub-millimeter magnetic materials into predefined circuits is of major importance for the realization of portable devices designed for telecommunications, automotive, biomedical, and space applications but remains highly challenging. We report here a versatile approach for the fabrication and direct integration of nanostructured magnetic materials of controlled shaped at specific locations onto silicon substrates. The magnetophoresis-assisted capillary assembly of magnetic nanoparticles, either spherical or anisotropic, leads to the fabrication of high-performance Co-based permanent magnets and Fe-based supercrystals. Integrated sub-millimeter magnets as well as millimeter self-standing magnets exhibiting magnetic properties competing with NdFeB-based composites were obtained through this cost- and time-efficient process. The proof-of-concept of electromagnetic actuation of a micro-electromechanical system cantilever by means of these supercrystals highlights their potentiality as efficient integrated magnetic materials within nomadic devices

Optimization of a vibrating MEMS electromagnetic energy harvester using simulations

International audienceNowadays, wireless sensor networks (WSN) are becoming essential in our daily life. However, a major constraint concerns the energy power supply. Indeed, batteries need to be recharged or replaced often which implies a limited lifetime for WSN nodes. One alternative consists in harvesting mechanical energy from surrounding vibrations of the environment. Using finite element simulations, we report here a complete guideline to optimize a MEMS electromagnetic energy harvester consisting of an in-plane vibrating silicon frame supporting an array of micromagnets that faces a static 2D micro-coil. The dimensioning of the magnet array and the specific design of the coil are addressed, considering patterned 50 µm thick NdFeB films with out of plane magnetization. The optimization of the electromechanical coupling which allows to efficiently convert the energy results from a trade-off between the high magnetic flux gradients produced by the micromagnets and the maximum number of turns of the facing coil