Assemblage contrôlé de graphène et de nanotubes de carbone par transfert de films de tensioactifs pour le photovoltaïque

Cette thèse est dédiée à l'étude d'une nouvelle méthode de formation de films ultra-minces de nanomatériaux carbonés sur surface. Basée sur le transfert d'un film d'eau stabilisé par des tensioactifs, elle permet notamment la réalisation et l'étude de films de nanotubes de carbone et d'oxyde de graphène (GO) aux propriétés remarquables. L efficacité de l approche développée est prouvée au travers de l ajustement précis des caractéristiques des films. Pour l assemblage d objets bidimensionnels cette approche est particulièrement pertinente puisque la planéité des feuillets de GO est conservée quelle que soit leur taille. Les avantages de l approche ne se limitent pas à la réalisation de monocouches à morphologie contrôlée mais s étendent à la réalisation de films multicouches d épaisseur ajustée et de très faible rugosité. De plus, cette approche est modulable et permet le transfert de films de nano-objets sur des surfaces de différentes mouillabilités et de grandes dimensions (transfert à l échelle de wafers). L intérêt du graphène oxydé en tant qu analogue du graphene ne se justifie que par une désoxygénation (réduction) efficace du matériau idéalement complétée par une réparation de sa structure sp . Cette thèse aborde ces deux aspects. Les électrodes transparentes à base d'oxyde de graphène réduit (rGO) réalisées au cours de cette thèse sont parmi les plus performantes du domaine. Les résultats présentés incluent également un travail important sur les caractérisations électriques des feuillets individuels et des films de GO et de rGO. Ainsi, nous avons prouvé qu il est possible de mesurer leur conductivité sans contact, par voie électrochimique (Scanning Electrochemical Microscopy). Même si les performances des électrodes en rGO n'atteignent pas celles des électrodes en graphène, les films réalisés peuvent d ores et déjà être intégrés dans des dispositifs photovoltaïques. Nos travaux permettent de contribuer au domaine émergeant des cellules basées sur l hétérojonction entre film de nano-objets carbonés et silicium. Dans le cadre de cette thèse nous montrons en particulier que les analyses par Time Resolved Microwave Conductivity sont complémentaires des mesures effectuées à l échelle des cellules photovoltaïques, chacune permettant de caractériser, sous des angles différents, l efficacité de séparation des charges photo-induites. Les travaux réalisés au cours de cette thèse contribuent aux problématiques dépendantes d assemblage et d intégration des nano-objets carbonés dans des dispositifs en ouvrant de nombreuses perspectives dans ces domaines en rapide évolution.This thesis concerns the study of a new solution-based deposition method for the formation of ultrathin carbon nano-object films on surfaces. Based on the transfer of a surfactant-stabilized water film, this method enables the formation and the study of carbon nanotubes and graphene oxide (GO) films with remarkable properties. The efficiency of the developed approach is proven through the fine-tuning of the film properties. This method is particularly well-suited for the assembly of bidimensional nano-objects such as GO sheets, the flatness of which is preserved whatever their dimensions. The advantages of the approach are not limited to the morphological control of monolayer assemblies but extend to the realization of multilayer films of adjustable thickness and extremely low roughness. Besides, it enables the transfer of nano-object films on large (wafer-scale) surfaces of various wettability. The use of graphene oxide as an intermediate step toward graphene only makes sense if it is efficiently deoxygenated (reduced) and, ideally, repaired at the level of sp domains. This thesis addresses these aspects. The realized transparent electrodes made of reduced graphene oxide (rGO) are among the most efficient in this field. The presented results also include an important work on the electrical characterization of graphene oxide sheets and films. We notably prove that conductivity can be measured without contact by an electrochemical way using Scanning Electrochemical Microscopy. While the performances of rGO electrodes are below those of graphene electrodes, the studied films can already be integrated into photovoltaic devices allowing to contribute to the emerging field of solar cells based on carbon/silicon heterojunctions. We particularly demonstrate that Time Resolved Microwave Conductivity analysis and photovoltaic cell measurements are complementary. Each of these techniques allows evaluating the efficiency of the separation of photo-induced charges. This thesis contributes to the dependent problematics of nano-object assembly and nano-object integration into devices, which are central for the development of nanotechnologies based on the bottom-up strategy.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Photonic titanium dioxide film obtained from hard template with chiral nematic structure for environmental application

International audienceIn the present work, mesoporous TiO 2 with a photonic structure was elaborated using cellulose nanocrystals (CNCs) as a biotemplate by two-step hard template methods. This strategy enables to replicate the chiral nematic (CN) structure of the photonic films (biotemplate) in TiO 2 films. A series of iridescent CNCs films with different weight ratios of silica/CNCs composite photonic films were prepared via evaporation induced self-assembly (EISA) method. The films showed iridescent color and tuneable Bragg reflection wavelengths by solely changing the ratio between the silica and the CNCs biotemplate. Polarized optical microscopy (POM) performed on hydride SiO 2 /CNCs films showed a birefringence and typical fingerprint of chiral nematic structure. This birefringence was also observed for TiO 2 films obtained using SiO 2 films as a hard template, which suggested the transfer of the chiral nematic structure in TiO 2 materials. Afterwards, their optical, morphological and electronic properties were studied by scanning electron microscope (SEM), POM, energy-dispersive X-ray spectroscope (EDX) and time resolved microwave conductivity (TRMC). The photocatalytic activities were evaluated by following the phenol degradation using high performance liquid chromatography (HPLC). The results showed that the structuration of the TiO 2 film using a chiral nematic SiO 2 film as hard template enhances the photocatalytic performance compared to non-structured mesoporous TiO 2

Handbook of Tsunami Evacuation Planning - SCHEMA (Scenarios for Hazard-induced Emergencies Management), Project n° 030963, Specific Targeted Research Project, Space Priority

This handbook is dedicated to provide thorough and hands-on information in order to produce fully-comprehensive methodology of tsunami evacuation plan generation. Hence community-employed decision makers or similar stakeholders are supplied with a detailed guideline to implement a fully-fledged evacuation plan within three stages : set-up of valid first instance of evacuation plan, mid-term revision, and long-term revision and integration. Local tsunami risk assessment and all subsequent implications on evacuation planning are based on (1) knowing the to-be-expected tsunami wave height, and (2) the to-be-expected arrival time of the first devastating tsunami wave. The first parameter helps to calculate the area at risk ; the second parameter gives an indication of how fast the evacuation has to take place. Consequently, the evacuation plan instance must guarantee that a certain number of affected persons has to be brought onto safe areas within a given time limit. Safe areas (shelters) are higher located places, either on natural ground, or on artificially built-up constructions including building higher than three stores. Evacuation has to take place on a given network of suitable roads or paths. In this context, if necessary, the methodology foresees also the inclusion of additionally to be built escape routes and/or safe places in order to produce a fully working evacuation plan that fulfills the basic requirements. The methodology also explains how to implement a valid instance of evacuation plan by marking the identified escape routes and shelters in reality, and how to disseminate all information to the affected population. Within a mid-term review the evacuation plan has to be maintained constantly and appropriate authority-own measures have to be guaranteed. The long-term review, finally, keeps track of all other information needed to run the evacuation plan properly : integration with early-warning systems, integration with other emergency plans, checking of legal obligations. In addition, the whole evacuation plan must be reviewed together with the affected population and a maximum of acceptance be obtained. In this contaxt, and if necessary, adaptations should be made in order to guarantee the well-functioning of the whole plan within its best performance.JRC.DG.G.7-Traceability and vulnerability assessmen

Manual de Planificação de Evacuação por Tsunami

Este manual tem como objectivo prestar informação detalhada e acessível, bem como uma metodologia abrangente de criação de planos para a evacuação de populações devido a tsunami. Desta forma, fica facultado aos decisores integrados nas comunidades ou outros actores semelhantes um guia detalhado sobre como implementar um plano de evacuação totalmente desenvolvido em três etapas: elaboração da primeira instância válida de plano de evacuação, revisão a médio prazo e revisão e integração a longo prazo. A determinação do risco de tsunami e todas as implicações subsequentes relativas ao plano de evacuação são baseadas no conhecimento da altura de onda de tsunami expectável e no tempo de chegada previsível da primeira onda devastadora. O primeiro parâmetro permite calcular a área em risco e o segundo fornece indicações sobre o tempo disponível para a concretização da evacuação. A evacuação deve ser feita numa determinada rede de estradas ou caminhos. Neste contexto, se necessário, a metodologia prevê a inclusão de rotas de fuga adicionais a serem construídas e/ou locais seguros, de modo a produzir um plano de evacuação totalmente funcional que preencha os requisitos básicos. Os locais seguros (abrigos) são locais situados a elevada altitude, em terreno natural ou em construções artificiais, incluindo edifícios com altura superior a três pisos. A metodologia descreve ainda o modo de implementar o plano de evacuação através da marcação das rotas de fuga identificadas e dos abrigos reais, bem como o modo de disseminar a informação à população afectada. No âmbito da revisão a médio prazo, o plano de evacuação deve ser mantido de forma constante, garantindo as medidas de autoridade apropriadas. A revisão a longo prazo, de um ponto de vista final, mantém o acompanhamento de toda a informação necessária para cumprir apropriadamente o plano de evacuação: integração com sistemas de aviso prévio existentes, com outros planos de emergência e a verificação de obrigações legais. Numa perspectiva idealista, o plano de evacuação deve ser revisto conjuntamente com a população afectada, de modo a garantir a máxima aceitação possível. Neste contexto, se necessário, deverão ser feitas adaptações para garantir o bom funcionamento de todo o plano, no contexto do seu desempenho maximizado. O manual apresenta igualmente os resultados obtidos a partir de entrevistas realizadas com pessoas potencialmente afectadas (em Setúbal), terminando com as dificuldades e limitações que podem surgir durante a geração de planos de evacuação. Este trabalho foi realizado no âmbito do projecto europeu co-financiado FP6 SCHEMA (SCenarios for Hazard-induced Emergencies MAnagement, www.schemeproject.org). O anexo contém uma descrição dos propósitos e objectivos alcançados do projecto, juntamente com a lista de parceiros.JRC.DG.G.7-Traceability and vulnerability assessmen

Keggin heteropolyacid H3PW12O40 supported on different oxides for catalytic and catalytic photo-assisted propene hydration

Catalytic and catalytic photo-assisted hydration of propene to form 2-propanol in gas–solid regime at atmospheric pressure and 85 1C were carried out by using a heteropolyacid (POM) supported on different oxides. Binary materials were prepared by impregnation of H3PW12O40 on different commercial and home prepared supports (TiO2, SiO2, WO3, ZrO2, ZnO, Al2O3). Some of the composites were active both for catalytic and catalytic photo-assisted reactions. The Keggin type POM was completely and partially degraded, when supported on ZnO and Al2O3, respectively, and these binary solids always resulted as inactive for both catalytic and catalytic photo-assisted reactions. The supported Keggin POM species played a key role both for the catalytic and the photo-assisted catalytic reactions, due to their strong acidity and ability to form strong oxidant species under UV irradiation, respectively. The contemporary presence of heat and UV light improved the activity of almost all POM supported materials. All materials were characterized by X-ray diffraction (XRD), scanning electron microscopy observations (SEM), diffuse reflectance spectroscopy (DRS), determination of the conduction and valence band energy by photovoltage measurements, Fourier transform infrared spectroscopy (FTIR), NH3-TPD experiments and time resolved microwave conductivity (TRMC). Introduction Propene hydration to obtain 2-propanol is a reaction carried out at moderate temperatures (ca. 150–200 1C) and pressure (2MPa) in the presence of an acid catalyst;1 however the realization of this reaction at ambient conditions is of great interest. The us

Social and Hydrological Responses to Extreme Precipitations: An Interdisciplinary Strategy for Postflood Investigation

International audienceThis paper describes and illustrates a methodology to conduct postflood investigations based on interdisciplinary collaboration between social and physical scientists. The method, designed to explore the link between crisis behavioral response and hydrometeorological dynamics, aims at understanding the spatial and temporal capacities and constraints on human behaviors in fast-evolving hydrometeorological conditions. It builds on methods coming from both geosciences and transportations studies to complement existing post-flood field investigation methodology used by hydrometeorologists. The authors propose an interview framework, structured around a chronological guideline to allow people who experienced the flood firsthand to tell the stories of the circumstances in which their activities were affected during the flash flood. This paper applies the data collection method to the case of the 15 June 2010 flash flood event that killed 26 people in the Draguignan area (Var, France). As a first step, based on the collected narratives, an abductive approach allowed the identification of the possible factors influencing individual responses to flash floods. As a second step, behavioral responses were classified into categories of activities based on the respondents' narratives. Then, aspatial and temporal analysis of the sequences made of the categories of action to contextualize the set of coping responses with respect to local hydrometeorological conditions is proposed. During this event, the respondents mostly follow the pace of change in their local environmental conditions as the flash flood occurs, official flood anticipation being rather limited and based on a large-scale weather watch. Therefore, contextual factors appear as strongly influencing the individual's ability to cope with the event in such a situation

Comprendre les comportements face à un risque modéré d’inondation. Etude de cas dans le périurbain toulousain (Sud-Ouest de la France)

Les espaces urbanisés soumis à des risques modérés d’inondation pour les vies humaines sont souvent peu considérés dans les études sur la vulnérabilité aux risques naturels en dépit des enjeux qu’ils représentent en termes de gestion de crise. Comment les riverains y font-ils face au danger et quelles sont leurs « bonnes raisons » d’agir? A partir de l’étude socio-géographique de deux inondations récentes (2000 et 2003) dans la périphérie toulousaine (Sud-Ouest de la France), nous montrons que les caractéristiques de l’aléa dans les vallées étudiées influencent les représentations du risque et par conséquent les motivations à se protéger. Face au risque majeur, la vulnérabilité sociale se trouve ainsi augmentée. Pour améliorer la résilience des populations, il convient d’adapter la communication sur les risques: personnaliser l’information, améliorer la compréhension de l’événement vécu et mobiliser de nouvelles formes de médiation entre gestionnaires et riverains

Heterologous Expression of Alteromonas macleodii and Thiocapsa roseopersicina [NiFe] Hydrogenases in Synechococcus elongatus

Oxygen-tolerant [NiFe] hydrogenases may be used in future photobiological hydrogen production systems once the enzymes can be heterologously expressed in host organisms of interest. To achieve heterologous expression of [NiFe] hydrogenases in cyanobacteria, the two hydrogenase structural genes from Alteromonas macleodii Deep ecotype (AltDE), hynS and hynL, along with the surrounding genes in the gene operon of HynSL were cloned in a vector with an IPTG-inducible promoter and introduced into Synechococcus elongatus PCC7942. The hydrogenase protein was expressed at the correct size upon induction with IPTG. The heterologously-expressed HynSL hydrogenase was active when tested by in vitro H2 evolution assay, indicating the correct assembly of the catalytic center in the cyanobacterial host. Using a similar expression system, the hydrogenase structural genes from Thiocapsa roseopersicina (hynSL) and the entire set of known accessory genes were transferred to S. elongatus. A protein of the correct size was expressed but had no activity. However, when the 11 accessory genes from AltDE were co-expressed with hynSL, the T. roseopersicina hydrogenase was found to be active by in vitro assay. This is the first report of active, heterologously-expressed [NiFe] hydrogenases in cyanobacteria