The sun provides us daily with large quantities of energy in the form of light. With the world’s increasing demand of electrical energy the prospect of converting this solar light into electricity is highly tempting. In the strive towards mass-production and low cost solar cells, new types of solar cells are being developed, e.g. solar cells completely based on organic molecules and polymers. These materials offer a promising potential of low cost and large scale manufacturing and have the additional advantage that they can be produced on flexible and light weight substrate which opens for new and innovating application areas, e.g. integration with paper or textiles, or as building materials. In polymer solar cells a combination of two materials are used, an electron donor and an electron acceptor. The three dimensional distribution of the donor and acceptor in the active layer of the device, i.e. the morphology, is known to have larger influence of the solar cell performance. For the optimal morphology there is a trade-off between sometimes conflicting criteria for the various steps of the energy conversion process. The dissociation of photogenerated excitons takes place at an interface between the donor and acceptor materials. Therefore an efficient generation of charges requires a large interface between the two components. However, for charge transport and collection at the electrodes, continuous pathways for the charges to the electrodes are required. In this thesis, results from morphology studies by atomic force microscopy (AFM) and dynamic secondary ion mass spectrometry (SIMS) of spin-coated blend and bilayer thin films of polyfluorene co-polymers, especially poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-5,5-(4´,7´-di-2-thienyl-2´,1´,3´-benzothiadiazole)] APFO-3, and the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) are presented. It is shown that by varying the blend ratio, the spin.-coating solvent, and/or the substrate, different morphologies can be obtained, e.g. diffuse bilayer structures, spontaneously formed multilayer structures and homogeneous blends. The connection between these different morphologies and the performance of solar cells is also analysed. The results indicate that nano-scale engineering of the morphology in the active layer may be an important factor in the optimization of the performance of polymer solar cells.

Lignocellulosic biomass (e.g., non food-based agricultural resides and forestry wastes) has recently been promoted for use as a source of bioethanol instead of food-based materials (e.g., corn and sugar cane), however to fully realize these benefits an improved understanding of lignocellulosic recalcitrance must be developed. The primary goal of this thesis is to gain fundamental knowledge about the surface of the plant cell wall, which is to be integrated into understanding biomass recalcitrance. Imaging mass spectrometry by TOF-SIMS and MALDI-IMS is applied to understand detailed spatial and lateral changes of major components in the surface of biomass under submicron scale. Using TOF-SIMS analysis, we have demonstrated a dilute acid pretreated poplar stem represented chemical differences between surface and bulk compositions. Especially, abundance of xylan was observed on the surface while sugar profile data showed most xylan (ca. 90%) removed from the bulk composition. Water only flowthrough pretreated poplar also represented difference chemistry between surface and bulk, which more cellulose revealed on the surface compared to bulk composition. In order to gain the spatial chemical distribution of biomass, 3-dimensional (3D) analysis of biomass using TOF-SIMS has been firstly introduced in the specific application of understanding recalcitrance. MALDI-IMS was also applied to visualize different molecular weight (e.g., DP) of cellulose oligomers on the surface of biomass.

No description available.

Cette thèse est focalisée sur la contribution de l'étude couplée de l'organisation multi-échelle et de la composition isotopique de C et N des carbones de météorites différenciées (acapulcoites - lodranites (A-L)), pour mieux comprendre l'histoire de leur corps-parent. Nous avons systématiquement combiné observations des carbones de ces météorites avec des analogues expérimentaux. Nous avons développé une méthodologie originale couplant l'étude de l'organisation des échelles micrométriques à nanométriques (par Microscopie Electronique par Transmission et Microspectrométrie Raman) et l'analyse isotopique des carbones (par SIMS) sur rigoureusement les mêmes plages de dimensions micrométriques. La comparaison avec les mélanges expérimentaux indique que le graphite d'Acapulco s'est formé par un mode de graphitisation "catalysée par le fer". L'absence de graphitisation des carbones de Lodran dans un environnement riche en fer et chaud est apparemment paradoxale. Toutes nos observations peuvent être réconciliées si nous considérons une collision tardive du corps-parent des A-L avec un corps chondritique apportant matière organique insoluble et chaleur d'impact. Ce scénario est conforté par les analyses isotopiques qui indiquent une formation des carbones des A-L par carbonisation d'un précurseur chondritique et une migration d'effluents carbonés au sein du corps-parent

Résumé : Les circuits photoniques intégrés qui combinent des dispositifs photoniques pour la génération, la détection, la modulation, l'amplification, la commutation et le transport de la lumière dans une puce, ont été rapportés comme étant une innovation technologique importante qui simplifie la conception du système optique et qui réduit l'espace et la consommation de l'énergie en améliorant ainsi la fiabilité. La capacité de modifier la bande interdite des zones sélectives des différents dispositifs photoniques à travers la puce est la clé majeure pour le développement de circuits photoniques intégrés. Comparé à d'autres méthodes d’épitaxie, l’interdiffusion de puits quantiques a attiré beaucoup d'intérêt en raison de sa simplicité et son efficacité en accordant la bande interdite durant le processus de post-épitaxie. Cependant, l’interdiffusion de puits quantiques a subi des problèmes reliés au manque de précision pour modifier convenablement la bande interdite ciblée et à l’incontrôlabilité de l’absorption des impuretés au cours du processus qui peut dégrader la qualité du matériel interdiffusé. Dans cette thèse, nous avons utilisé les lasers excimer pour créer des défauts à proximité de la surface (~ 10 nm) des microstructures à base de puits quantiques III-V (par exemple InP et GaAs) et pour induire l’interdiffusion après le recuit thermique. L'irradiation par les lasers excimer (ArF et KrF) des microstructures à puits quantiques a été réalisée dans différents environnements, y compris l'air, l'eau déionisée, les couches diélectriques (SiO2 et Si3N4) et les couches d’InOx. Pour proposer un bon contrôle de la technique d’interdiffusion de puits quantiques par laser excimer, nous avons étudié la génération et la diffusion de défauts de surface en utilisant différentes méthodes de caractérisation de surface/interface, comme l'AFM, SEM, XPS et SIMS qui ont été utilisées pour analyser la modification de la morphologie de surface/interface et la modification chimique de la microstructure de ces puits quantiques. La qualité des microstructures à puits quantiques étudiées a été représentée par des mesures de photoluminescence et de luminescence des diodes lasers ainsi fabriqués. Les résultats montrent que le laser excimer induit des quantités d'oxydes de surface dans les surfaces des microstructure à puits quantiques InP/InGaAs/InGaAsP dans l'air et des impuretés d'oxygène des couches d'oxydes diffusées dans la région active de la microstructure lors du recuit, ce qui améliore l’interdiffusion, mais réduit l'intensité de la photoluminescence. Par contre, l’irradiation dans un environnement d'eau déionisée n’a pas démontré de diffusion des impuretés évidentes d'un excès d'oxygène vers les régions actives, mais la stœchiométrie de surface a été restaurée après l’interdiffusion. L’InOx a été trouvé avec un grand coefficient de dilatation thermique dans la microstructure interdiffusée qui était supposée d’augmenter la contrainte de compression dans la région active et ainsi d’augmenter l'intensité de photoluminescence de 10 fois dans l’échantillon irradié dans l'eau déionisée. Concernant les microstructures avec une couche diélectrique, la modification de la bande interdite a été toujours réalisée sur des échantillons dont les couches diélectriques ont été irradiées et la surface de InP a été modifiée par le laser excimer. Pour l'échantillon avec une couche de 243 nm de SiO2, les variations de la photoluminescence ont été mesurées sans l’ablation de cette couche de SiO2 lors de l'irradiation par le laser KrF. Cependant, la morphologie de l'interface d’InP a été modifiée, les oxydes d'interface ont été générés et les impuretés d'oxygène se sont diffusées à l'intérieur des surfaces irradiées. Les améliorations de l’interdiffusion dans les deux surfaces non irradiées et irradiés de l'échantillon couvert de couche d’InOx ont démontré l'importance des oxydes dans l’interdiffusion des puits quantiques. Les diodes laser fabriquées à partir d’un matériau interdiffusé par un laser KrF ont montré un seuil de courant comparable à celui des matériaux non interdiffusés avec un décalage de photoluminescence de 100 nm. En combinant un masque d'aluminium, nous avons créé un déplacement uniforme de photoluminescence de 70 nm sur une matrice rectangulaire de 40 μm x 200 μm ce qui présente un potentiel d’application de l’interdiffusion des puits quantiques par les lasers excimer dans les circuits photoniques intégrés. En outre, les lasers excimer ont été utilisés pour créer des structures de nano-cônes auto-organisées sur des surfaces de microstructure de InP/InGaAs/InGaAsP en augmentant l'intensité de PL par ~ 1.4 fois. Les lasers excimer ont été aussi utilisés pour modifier la mouillabilité sélective des zones d’une surface de silicium par une modification chimique de surface induite par laser dans différents milieux liquides. Ainsi, la fluorescence des nanosphères a été réussie pour des fonctions de configuration spécifique avec une surface de silicium. // Abstract : Photonic integrated circuits (PICs) which combine photonic devices for generation, detection, modulation, amplification, switching and transport of light on a chip have been reported as a significant technology innovation that simplifies optical system design, reduces space and power consumption, improves reliability. The ability of selective area modifying the bandgap for different photonic devices across the chip is the important key for PICs development. Compared with other growth methods, quantum well intermixing (QWI) has attracted amounts of interest due to its simplicity and effectiveness in tuning the bandgap in post-growth process. However, QWI has suffered problems of lack of precision in achieving targeted bandgap modification and uncontrollable up-taking of impurities during process which possibly degrade the quality of intermixed material. In this thesis, we have employed excimer laser to create surface defects in the near surface region (~ 10 nm) of III-V e.g. InP and GaAs, based QW microstructure and then annealing to induce intermixing. The irradiation by ArF and KrF excimer lasers on the QW microstructure was carried out surrounded by different environments, including air, DI water, dielectric layers (SiO2 and Si3N4) and InOx coatings. To propose a more controllable UV laser QWI technique, we have studied surface defects generation and diffusion with various surface/interface characterization methods, like AFM, SEM, XPS and SIMS, which were used to analyse the QW surface/interface morphology and chemical modification during QWI. The quality of processed QW microstructure was represented by photoluminescence measurements and luminescence measurements of fabricated laser diodes. The results shows that excimer laser induced amounts of surface oxides on the InP/InGaAs/InGaAsP microstructure surface in air and the oxygen impurities from oxides layer diffused to the active region of the QW microstructure during annealing, which enhance intermixing but also reduce the PL intensity. When irradiated in DI water environment, no obvious excessive oxygen impurities were found to diffuse to the active regions and the surface stoichiometry has been restored after intermixing. InOx with large coefficient of thermal expansion was found inside the intermixed QW microstructure, which was supposed to increase the compressive strain in active region and enhance the PL intensity to maximum 10 times on sample irradiated in DI water. On microstructure coated with dielectric layers, bandgap modifications were always found on samples whose dielectric layers were ablated and InP surface was modified by excimer laser. On sample coated with 243 nm SiO2 layer, the PL shifts were found on sample without ablation of the SiO2 layer when irradiated by KrF laser. However, the InP interface morphology was modified, interface oxides were generated and oxygen impurities have diffused inside on the irradiated sites. The enhancements of interdiffusion on both non irradiated and irradiated sites of sample coated with InOx layer have verified the importance of oxides in QWI. The laser diodes fabricated from KrF laser intermixed material have shown comparable threshold current density with as grown material with PL shifted by 133 nm. Combined aluminum mask, we have created uniform 70 nm PL shifts on 40 μm x 200 μm rectangle arrays which presents UV laser QWI potential application in PICs. In addition, excimer lasers have been used to create self organized nano-cone structures on the surface of InP/InGaAs/InGaAsP microstructure and enhance the PL intensity by ~1.4x. Excimer lasers have selective area modified wettability of silicon surface based on laser induced surface chemical modification in different liquid environments. Then the fluorescence nanospheres succeeded to specific pattern functions with silicon surface.

Solar cells constitute the most direct way of converting solar energy to electricity, and thin-film solar-cell technologies have lately been growing in importance, allowing the fabrication of less expensive modules that nonetheless have good power-conversion efficiencies. This thesis focuses on solar cells based on Cu(In,Ga)Se2, which is the thin-film technology that has shown the highest conversion efficiency to date, reaching 20.3 % on the laboratory scale. Solar modules still have some way to go to become entirely competitive with existing energy technologies, and there are two possible paths to this goal: Firstly, reducing their manufacturing costs, for instance by minimizing the material usage per module and/or by increasing the throughput of a given factory; and secondly, increasing the power output per module in other words, the module efficiency. The subject matters of this thesis are related to those two approaches. The first issue investigated is the possibility for reducing the thickness of the Cu(In,Ga)Se2 layer and compensating for lost absorption by using a ZrN back reflector. ZrN layers are fabricated by reactive sputtering and I present a method for tuning the sputtering parameters so as to obtain a back reflector with good optical, electrical and mechanical properties. The reflector layer cannot be used directly in CIGS devices, but relatively good devices can be achieved with a precursor providing a homogeneous supply of Na, the addition of a very thin sacrificial Mo layer that allows the formation of a film of MoSe2 passivating the back contact, and optionally a Ga gradient that further keeps electrons away from the back contact. The second field of study concerns the three-stage CIGS coevaporation process, which is widely used in research labs around the world and has yielded small-area cells with highest efficiencies, but has not yet made it to large scale production. My focus lies on the development and the effect of gradients in the [Ga]/[In+Ga] ratio. On the one hand, I investigate 'intrinsic' gradients (ones that form autonomously during the evaporation), and present a formation model based on the differing diffusivity of Ga and In atoms in CIGS and on the development along the quasi-binary tie line between (In,Ga)2Se3 and Cu2Se. On the other hand, I determine how the process should be designed in order to preserve 'extrinsic' gradients due to interdiffusion. Lastly, I examine the electrical effects of Ga-enhancement at the back and at the front of the absorber and of In-enhancement at the front. Over a wide range, In-rich top layers prove to have no or a weakly beneficial effect, while Ga-rich top regions pose a high risk to have a devastating effect on device performance.

This dissertation aims to analyze, under the gaze of Discourse Analysis of the French line, the possibility of a pedagogical discourse embedded in an electronic game that simulate life, characters and environments (played on computer or mobile phone) to support the processes of teaching and learning. The analysis seeks by tools and opportunities to discuss the possibility of rupture of the authoritarianism of pedagogical discourse. Among the reasons that prompted the researcher to proceed with the analysis were the popularization of resources that we can find in an electronic game that simulate life, characters and environments including cognitive resources, the ability to play the game through technologies like the mobile phone and computer, contradictions between laws that banning cell phone and computer games at school, and the educational approach provided by the Brazilian federal constitution of 1988. The features that may help do difference with a electronic game that simulate life, characters and environments in the teaching and learning processes of the schools are the interaction, simulation, challenges, problem solving, and production of visual and written texts. The concepts of Education, Ideology, Discourse Analysis, typology of discourse, pedagogical discourse, electronic discourse and the discursive trends are the scientific theory support. In order to contextualize the game The Sims2 in the world of games was created a description of a history of games since ancient times until the advent of electronic games. The analysis was described from the images, simulation and challenge tools that show the Discourses of the game. The typology of Discourse developed by Eni Orlandi (2009) explains about the types of operation of the discursive trends of the discourses inserted in them (the images and tools of the game) that are the base for the comparison between the discourses that are produced of discursive positions of the game makers and game players with the discourse of school, the pedagogical discourse. In the end of this dissertation are suggested proposals, challenges and also the conclusions about the analysis that may help teachers and learners when electronic games that simulate life, characters and environments, such as "The Sims2" from EA Games, may be played in the schools as a tool that helps teachers and students in the teaching and learning processes / Submitted by Jovina Laurentino Raimundo (jovina.raimundo@unisul.br) on 2018-01-17T16:51:18Z No. of bitstreams: 1 103804_Roberto.pdf: 5108578 bytes, checksum: 7d7ae2bf9783107cbe0a31ce9c7280f5 (MD5) / Approved for entry into archive by Gheovana Figueiredo (gheovana.figueiredo@unisul.br) on 2018-01-17T17:19:56Z (GMT) No. of bitstreams: 1 103804_Roberto.pdf: 5108578 bytes, checksum: 7d7ae2bf9783107cbe0a31ce9c7280f5 (MD5) / Made available in DSpace on 2018-01-17T17:19:56Z (GMT). No. of bitstreams: 1 103804_Roberto.pdf: 5108578 bytes, checksum: 7d7ae2bf9783107cbe0a31ce9c7280f5 (MD5) Previous issue date: 2011 / Esta dissertação visa analisar, sob o olhar da Análise de Discurso da linha Francesa, a possibilidade de um discurso pedagógico inserido num jogo eletrônico (rodado em computador ou telefone celular) como apoio aos processos de ensino e aprendizagem. A Análise busca fundamentos para discutir a possibilidade de ruptura do autoritarismo do discurso pedagógico. O objeto de análise são os discursos produzidos a partir da posição discursiva de sujeito autor (fabricante do jogo) e de sujeito leitor (jogador) presentes nas imagens e ferramentas de simulação e desafio do jogo The Sims2, da EA Games. Os motivos que impulsionaram o pesquisador a investir na análise foram a popularização e os recursos incorporados aos jogos de simulação de vida e ambientes, entre eles os recursos cognitivos, a possibilidade de jogar o jogo através de tecnologias como o telefone celular e o computador, as contradições entre leis que proíbem o telefone celular e os jogos eletrônicos na escola, e a proposta educacional prevista pela constituição federal de 1988. Entre os recursos que podem ser diferenciados através dos jogos de simulação de vida e ambientes nos processos de ensino e aprendizagem das escolas estão a interação, a simulação, os desafios, a solução de problemas e a produção de textos visuais e escritos. A fundamentação teórica tem como suporte recortes de conceitos sobre Educação, Ideologia, Análise do Discurso, Tipologia dos discursos, Discursos Pedagógico e Eletrônico e respectivas tendências discursivas. Para contextualizar o recorte do jogo The Sims2 descreveu-se um histórico dos jogos desde a antiguidade até o advento dos jogos eletrônicos. A análise foi descrita a partir das imagens, ferramentas de simulação e ferramentas de desafio que mostram as posições discursivas presentes no jogo. A Tipologia do Discurso de Eni Orlandi (2009) que explica a tipologia das tendências de funcionamento dos discursos nelas inseridas (nas imagens e ferramentas do jogo) fundamenta a comparação entre os discursos que são produzidos a partir da posição discursiva dos sujeitos envolvidos com o jogo, sujeito jogador e sujeito fabricante, com o discurso da escola, o discurso pedagógico. No final desta dissertação são sugeridas propostas, desafios e também as conclusões sobre a análise que pode ajudar professores e alunos quando os jogos eletrônicos que simulam a vida, personagens e ambientes, tais como "The Sims2" da EA Games, podem ser jogados nas escolas como uma ferramenta que ajuda professores e alunos em processos de ensino e aprendizagem

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2016-09-14T17:52:07Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação PPGA - Fruticultura - Diego Weber.pdf: 3305024 bytes, checksum: 66ae9f28f00f60359ff57524fe3c8cb1 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-09-15T19:27:15Z (GMT) No. of bitstreams: 2 Dissertação PPGA - Fruticultura - Diego Weber.pdf: 3305024 bytes, checksum: 66ae9f28f00f60359ff57524fe3c8cb1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-09-15T19:27:15Z (GMT). No. of bitstreams: 2 Dissertação PPGA - Fruticultura - Diego Weber.pdf: 3305024 bytes, checksum: 66ae9f28f00f60359ff57524fe3c8cb1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2013-03-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A fruticultura apresenta-se como importante fonte de renda ao alcance do pequeno agricultor familiar, devido a alta demanda de mão de obra e o considerável rendimento para pequenas propriedades. Uma frutífera adaptada e de grande potencial no Brasil é o maracujazeiro-amarelo (Passiflora edulis Sims), devido o seu ciclo produtivo ser relativamente curto, alta produtividade e ótima qualidade do suco. Com a adaptabilidade da cultura na diversidade edafoclimática do Brasil, faz -se possível a produção de maracujá-amarelo em todas as regiões do país. Entretanto, pouco se conhece de seu crescimento, desenvolvimento e desempenho nas condições edafoclimáticas do Sul do Rio Grande do Sul, onde tem se invernos com geadas e verões mais curtos em relação as regiões tropicais. Objetivou-se avaliar as características produtivas e físico-químicas dos frutos do maracujazeiro-amarelo produzidos em Pelotas/RS, sob três densidades de plantio. O trabalho foi desenvolvido na UFPel/FAEM, nos anos de 2011 e 2012. Utilizou-se a seleção ‘Ovalado Grande’ de maracujazeiro-amarelo, desenvolvida pela Epagri/EEUR. O plantio foi realizado em outubro de 2011, sob sistema de condução em espaldeira, com irrigação por gotejamento e polinização manual. Os tratamentos (densidade de plantio) foram: tratamento D1 com distância entre plantas de 2,5m utilizando uma planta por cova, 1.600 plantas por hectare (plantas ha -¹); tratamento D2 com distância entre plantas de 1,5m utilizando uma planta por cova, 2.666 plantas ha -¹ e; tratamento D3 com distância entre plantas de 2,5m utilizando duas plantas por cova, 3.200 plantas ha -¹. Em todos os tratamentos o espaçamento entre filas foi de 2,5m. As variáveis de produção foram: produtividade estimada (P), produção por planta(PP), número de frutos por planta (NFP), número de frutos por hectare (NFH), massa média de frutos (MMF) e dias da antese até a maturação do fruto (DAMF). As variáveis físico-químicas foram: sólidos solúveis (SS), acidez titulável (AT), relação SS/AT (RATIO), coloração da epiderme (CE), espessura média do pericarpo (EP), comprimento médio do fruto (CMF), diâmetro médio do fruto (DMF) e rendimento de polpa (RP). Não houve diferença estatística significativa entre os tratamentos para as variáveis MMF (249,24g) e DAMF (73,5 dias). Para as variáveis de produção, PP, NFP e NFH houve superioridade para os sistemas menos adensados, assim o tratamento D1, obteve melhor desempenho. Porém, considerando que o adensamento no plantio do maracujazeiro-amarelo promove maior produtividade, o tratamento D3 obteve melhor desempenho produtivo neste contexto, alcançando uma excelente produtividade, de 25,45 t ha -¹. Para as variáveis físico-químicas, não houve influência dos tratamentos em todas as variáveis. Porém os frutos apresentaram ótima qualidade, com ótimo padrão para o mercado ‘in natura’ , com valores considerados de alto padrão para as variáveis CMF (107,30mm), DMF(85,39mm), SS (11,25ºBrix) AT (5,67%) e EP (5,73mm) e RP (51,42%). Recomendase o cultivo do maracujazeiro-amarelo na região de Pelotas, RS, utilizando-se a densidade de plantio de 3.200 plantas ha -¹ (2,5 x 2,5m com duas mudas por cova). / The fruticulture presents itself as important income source adapted for the small family farmer, due to high demand on hand labor and high performance on small farms. A fruit tree adapted and great potential in Brazil is the yellow Passion fruit (Passiflora edulis Sims), due its production cycle to be relatively short, high productivity and high quality juice. According to the excellent adaptability of culture diversity in climate and soil of Brazil, it is possible the production of Passion fruit in all regions of the country. However, little is known of their growth, development and performance at conditions of southern Rio Grande do Sul, where there winters with frosts and shorter summers over the tropics. This study aims to evaluate the productive and physicochemical characteristics in fruits of yellow Passion fruit tree produced in Pelotas/RS, under three planting densities. The work was developed in UFPel/FAEM, in the years 2011 and 2012. It was used the selection ‘Ovalado Grande' of yellow Passion fruit, developed by Epagri/EEUR. The planting was realized in October 2011, under the conduction system in trellis, with drip irrigation and manual pollination. The treatments (planting density) were: treatment D1 with distance of 2,5m between plants using one plant per hole, 1.600 plants per hectare (plants ha -¹); treatment D2 with distance of 1,5m between plants using o ne plant per hole, 2.666 plants ha -¹; treatment D3 with distance of 2,5m between plants using two plants per hole, 3.200 plants.ha -¹. In all treatments the spacing between rows was 2,5m. The production variables were estimated productivity (P), production per plant (PP), number of fruits per plant (NFP), number of fruits per hectare (NFH), average fruit weight (MMF) and days from anthesis through fruit ripening (DAMF). The physicochemical variables were: soluble solids (SS), titratable acidity (AT), SS/AT ratio (RATIO), skin color (CE), the average thickness of pericarp (EP), the average length of fruit (CMF) average width of fruit (DMF) and yield pulp (RP). There was no statistically significant difference between treatments for the variables MMF (249,24g) and DAA (73,5 days). For the production variables, PP, NFP and NFH were superior to systems less dense, so the treatment D1, performed better. However, considering that higher density planting of yellow Passion fruit promotes greater produtivity, the treatment D3 obtained better performance in this context, achieving an excellent produtivity, 25,45 t ha -¹. For physicochemical variables, there was no influence of the treatments on all variables. However, fruits showed great quality, with excellent standard for the fresh fruit market, with values considered high standard for the variables CMF (107,30mm), DMF (85,39mm), SS (11.25ºBrix) AT (5,67%), EP (5,73mm) and RP (51,42%). It is recommended the cultivation of yellow Passion fruit tree in Pelotas, RS, using a planting density of 3.200 plants ha -¹ (2,5 x 2,5m with two plants per hole).

Le silicium est un matériau étudié depuis plusieurs années comme une sérieuse alternative au graphite dans les batteries Li-ion. Ce travail de thèse vise à développer des approches alternatives et complémentaires à celles déjà existantes afin de mieux comprendre les mécanismes de lithiation et de dégradation. L'analyse croisée entre plusieurs techniques, principalement FIB-ToF-SIMS, Auger, XPS et FIB-MEB, point central de l'étude, nécessite la mise en place de protocoles spécifiques prenant en compte la forte réactivité des échantillons lithiés. En premier lieu, un couplage entre ToF-SIMS et XPS sur des couches minces de silicium, permet de mettre en évidence la présence d'une phase riche en lithium ségrégée à l'interface entre la couche de matériau actif et le collecteur de courant en cuivre. Un mécanisme particulier de lithiation du silicium, basé sur l'existence de chemins de diffusion rapide pour le lithium, est suggéré. La réalisation de coupes FIB effectuées in situ dans la chambre d'analyse du ToF-SIMS sur des électrodes à base de poudre micrométrique de Si permet ensuite de proposer un mécanisme de lithiation analogue à celui mis en évidence précédemment. En outre, la présence de grains déconnectés du réseau percolant de l'électrode au cours du cyclage et piégeant le lithium est mise en évidence et contribue à la défaillance rapide de la batterie. Enfin, la méthodologie développée est appliquée à l'étude d'électrodes composées de Si nanométrique et de composite Si/C. Elle participe à l'établissement d'un modèle de croissance de SEI à la surface de grains de silicium nanométriques et permet d'identifier les raisons de la défaillance de ces électrodes. / Silicon is a serious option to replace graphite in anodes for Li-ion batteries since it offers a specific capacity almost ten times higher. However, silicon anodes suffer from a drastic capacity fading, making it unusable after a few cycles. The work presented here aims at the development of new alternative and complementary approaches to those currently used, in order to better understand lithiation and degradation mechanisms. These methods are based on cross-analysis between several surface characterizations techniques, including FIB-ToF-SIMS, AES, XPS and FIB-MEB, which require specific procedures to deal with the extreme sensitivity of lithiated materials. Coupling XPS and ToF-SIMS on silicon thin films revealed the presence of a Li-rich phase segregated at the interface between silicon and Cu current collector. A mechanism based on fast diffusion paths for lithium is suggested. In situ FIB milling, performed in the analysis chamber of the ToF-SIMS on anodes using micrometer-sized silicon particles, revealed a similar mechanism involving fast diffusion paths for lithium. Additional TEM observations suggest that, in the case of micrometer-sized particles, these paths result from sub-grain boundaries. Additionally, the presence of Li trapped in Si particles which are disconnected from the conductive grid along cycling is shown, contributing to the poor battery lifespan. Finally, the developed method has been applied to electrodes based on nanometer-sized Si particles and Si/C composite. Despite of the small size of the involved particles, it is possible to get information about SEI growth on the surface of nano-sized silicon particles and to identify causes of failure.

Les alliages légers d'aluminium de la série 2000 sont utilisés dans l'industrie aéronautique en raison de leurs excellentes propriétés mécaniques. Ils sont néanmoins sensibles à la corrosion localisée, et nécessitent d'être protégés. Les couches de conversion permettent une protection efficace. La conversion utilisée aujourd'hui est à base de chrome hexavalent (CrVI), composé cancérogène, devant être remplacé. L'étude de nouveaux procédés est nécessaire, et ce travail a porté sur l'utilisation de couches de conversion au chrome trivalent (CrIII, procédé TCP), en combinant des méthodes d'analyse des surfaces (XPS, ToF-SIMS, AFM), des essais de corrosion et des mesures électrochimiques. L'influence des prétraitements sur le dépôt de la couche TCP a été étudiée. Lors du décapage sulfo-ferro-nitrique, un enrichissement en cuivre métallique, la dissolution des particules riches en cuivre et le retrait de l'oxyde d'aluminium natif sont observés. La couche de conversion déposée après ce décapage est moins couvrante que sur une surface qui a été nettoyée mais non décapée par cette méthode. Les résultats de tenue en corrosion confirment l'influence néfaste du décapage sur la protection apportée par les couches TCP. Une étude du dépôt de la couche TCP sur un substrat d'aluminium préalablement recouvert par ALD d'une couche fine et homogène d'alumine a été réalisée. Une épaisseur critique d'oxyde d'aluminium a pu être déterminée au-delà de laquelle le dépôt d'une couche TCP est bloqué. Un modèle a été proposé pour expliquer le mécanisme de dépôt de la couche de conversion sur une surface recouverte d'une couche mince d'oxyde d'aluminium. / Light 2xxx aluminium alloys are widely used in the aircraft industry because of their good mechanical properties. However, they are prone to localized corrosion and must be protected. Conversion coatings allow such protection. Nowadays, chromate conversion coatings (CrVI) are still used but they must be replaced. New systems are tested, and in this work we investigated the Trivalent Chromium Process (TCP, CrIII based), by combining surface analysis techniques (XPS, ToF-SIMS, AFM), corrosion tests and electrochemical measurements.The influence of surface pretreatments on the TCP coating deposition has been studied. During the etching step, a metallic copper enrichment, the dissolution of Cu-rich intermetallic particles and the removal of the native aluminium oxide are observed. The subsequent TCP deposited layer is less continuous on such pretreated alloy surfaces than on non-etched, only cleaned alloy surfaces. These results show the importance of the presence of the native oxide layer on the alloy surface. A study of the TCP coating deposition on a pure aluminium pre-coated with a thin homogeneous alumina layer (deposited by Atomic Layer Deposition) shows a critical thickness of the alumina, beyond which, the TCP deposition is blocked. A deposition mechanism of the TCP layer on a thin aluminium oxide is presented.