82 research outputs found

    Post-modification par irradiation g de polymères à base de fluorure de vinylidène (Applications aux membranes séparatrices de supercapacité)

    Get PDF
    Ce travail porte sur la modification de matrices polymères à base de fluorure de vinylidene pour permettre leur utilisation en tant que membrane séparatrice dans les supercapacités. Basé sur un procédé d irradiation par rayonnement g, l objectif principal était la limitation du gonflement du polymère lorsqu il est mis en contact d un milieu liquide relatif à l application tout en gardant d excellentes affinités avec celui-ci. Le processus de base exploité étant la formation et la réaction des radicaux lors de l irradiation du polymère, une partie de la thèse a été consacrée à leur étude par résonance paramagnétique électronique (RPE). Un modèle de simulation de spectre RPE a été mis en place pour identifier et quantifier chacune des espèces radicalaires. L effet de la dose d irradiation, de la durée d un recuit et de la nature de la matrice polymère (homo, copolymère) sur la proportion de ces espèces et sur leur réactivité a été évalué. Un lien avec la formation d un réseau a été proposé. Une attention particulière a ensuite été apportée à l augmentation de la densité de réticulation avec le concours d un agent réticulant, le TAIC. Pour terminer, une stratégie de modification des propriétés de surface du PVDF a été élaborée. Elle consiste dans un premier temps à radiogreffer un polymère à la surface du PVDF puis à modifier, dans un second temps, les greffons par une chimie douce et sélective. En conclusion, les approches complémentaires développées au cours de cette thèse ont permis de comprendre la radiolyse des polymères et de mettre à profit les processus élémentaires pour développer des stratégies robustes et prometteuses de modulation des propriétés.This work deals with the modification of VDF-based polymer induced by g-radiation as the polymer may be used in electrochemical supercapacitors. The main objective was to limit the swelling of the fluorinated matrix with a given electrolyte while a good wetting of the polymer by the liquid was also required. As the main basic process involved in polymer radiolysis is the formation of radicals, a part of the work was dedicated to the study of such species by using Electron Spin Resonance spectroscopy. A simulation model of ESR spectra was established in order to identify and quantify each radical species. The effect of several parameters such as radiation dose, annealing time or the nature of polymer matrix on the concentration of each species where investigated. A relation with the evolution of the crosslink density of the network formed during the radiolisys was proposed. In addition, one of the key steps of this work was to study the radiation crosslinking ability of VDF-based polymers and find a way to increase the crosslink density. This was achieved by incorporating, prior to the radiation process, a radiation sensitive crosslinker: TAIC. Finally, a new strategy based on the modification of surface properties of PVDF was investigated. It consists in the radiation grafting of pentafluorstyrene onto PVDF surface followed by the chemioselective functionalization of the grafted segments. As a conclusion, the different approaches used in this thesis allowed us to understand the radiolysis of VDF-based polymers and take advantage of the elementary process involved in this type of chemistry, to build up robust and promising strategies for tuning properties.VILLEURBANNE-DOC'INSA-Bib. elec. (692669901) / SudocSudocFranceF

    Ultrafast energy transfer from local exciton to intermolecular CT states in a supramolecular model of the donor–acceptor interfaces

    Get PDF
    Abstract : The donor–acceptor contacts in bulk heterojunctions (BHJ) is the birthplace of primary energy leaks in organic solar cells (OSCs): Voc (voltage at open circuit) losses. These interfaces are the least understood and the least accessible experimentally. A bottom up approach is being used to mimic this interface via supramolecular interactions of two graphene-based materials: reduced graphene oxide, RGO, and, graphene nanoribbon, GNR, with six different pyrene-linked dyes used as probes to assess the photophysical changes observed upon interface formation in a donor–acceptor bulk heterojunction device. These assemblies are secured through strong π–π interactions between pyrene anchors and GNR, and the formation of these probe–GNR assemblies were studied by absorption spectroscopy. A total of 11 static charge transfer (CT) complexes were identified in 6 different donor–acceptor interfaces, and their properties and dynamics were studied by steady state, time-resolved fluorescence and transient absorption spectroscopy. Three distinct cases were identified: (1) nonharvesting CT assemblies, (2) harvesting and emissive CT assemblies, and (3) harvesting but nonemissive CT complexes. The excitons of the GNR chains are rapidly and fully channeled to the CT complex (<1 ps). Depending on the driving force, the formation of long-lived CT states (302–483 ps) is observed. A three-state model with a coupling between a CT state and a local exciton (LE) is used to describe the behavior of this interface. A HOMOGNR–HOMO2PyrPBI energy gap of 0.16 eV is found to be large enough to efficiently promote a pure charge transfer state at the interface

    Skiroc: A Front-end Chip to Read Out the Imaging Silicon-Tungsten Calorimeter for ILC

    Get PDF
    Integration and low-power consumption of the read-out ASIC for the International Linear Collider (ILC) 82-millionchannel W-Si calorimeter must reach an unprecedented level as it will be embedded inside the detector. Uniformity and dynamic range performance has to reach the accuracy to achieve calorimetric measurement. A first step towards this goal has been a 10,000-channel physics prototype of 18*18 cm which is currently in test beam in CERN. A new version of a full integrated read out chip (SKIROC) has been designed to equip the technologic prototype to be built for 2009. Based on the running physics prototype ASIC (FLC_PHY3), it embeds most of the required features expected for the final detector. The dynamic range has been improved from 500 to 2000 MIP. An auto-trigger capability has been added allowing built-in zero suppress. The number of channel has been doubled reaching 36 to fit smaller silicon pads and the lownoise charge preamplifier now accepts both AC and DC coupled detectors. After an exhaustive description, the measurement results of that new front-end chip will be presented. The results on the technological R&D concurrently conducted on the ultra-thin PCB hosting both the front-end electronic and the silicon detectors will also be described

    Rackham: An Interactive Robot-Guide

    Get PDF
    International audienceRackham is an interactive robot-guide that has been used in several places and exhibitions. This paper presents its design and reports on results that have been obtained after its deployment in a permanent exhibition. The project is conducted so as to incrementally enhance the robot functional and decisional capabilities based on the observation of the interaction between the public and the robot. Besides robustness and efficiency in the robot navigation abilities in a dynamic environment, our focus was to develop and test a methodology to integrate human-robot interaction abilities in a systematic way. We first present the robot and some of its key design issues. Then, we discuss a number of lessons that we have drawn from its use in interaction with the public and how that will serve to refine our design choices and to enhance robot efficiency and acceptability

    Long-term analysis of the RiBVD phase II trial reveals the unfavorable impact of <i>TP53</i> mutations and hypoalbuminemia in older adults with mantle cell lymphoma; for the LYSA group

    Get PDF
    Between 2011 and 2012, a phase II trial evaluated the use of the RiBVD (rituximab, bendamustine, velcade and dexamethasone) combination as first-line treatment for mantle cell lymphoma (MCL) patients over the age of 65. We have now re-examined the classic prognostic factors, adding an assessment of TP53 mutation status. Patients (N=74; median age 73 years) were treated with the RiBVD combination. Median progression-free survival (mPFS) was 79 months and median overall survival (mOS) was 111 months. TP53 mutation status was available for 54/74 (73%) patients. TP53 mutations (TP53mt) were found in 12 patients (22.2%). In multivariate analysis, among the prognostic factors (PF) evaluated, only TP53mt and an albumin level (Alb) 3.6 g/dL were independently associated with a shorter mPFS. A hazard ratio (HR) of 3.16 (1.3-9.9, P=0.014) was obtained for TP53mt versus TP53 wild-type (wt), and 3.6 (1.39-9.5, P=0.009) for Alb <3.6 g/dL versus Alb ≥3.6 g/dL. In terms of mOS, multivariate analysis identified three PF: TP53mt (HR: 5.9 [1.77-19.5, P=0.004]), Alb <3.6 g/dL (HR: 5.2 [1.46- 18.5, P=0.011]), and ECOG=2 (HR: 3.7 [1.31-10.6, P=0.014]). Finally, a score combining TP53 status and Alb distinguished three populations based on the presence of 0, 1, or 2 PF. For these populations, mPFS was 7.8 years, 28 months, and 2.5 months, respectively. Our prolonged follow-up confirmed the efficacy of the RiBVD regimen, comparing it favorably to other regimens. TP53mt and hypoalbuminemia emerge as strong PF that can be easily integrated into prognostic scores for older adult patients with MCL

    Enabling planetary science across light-years. Ariel Definition Study Report

    Get PDF
    Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution
    corecore