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Kinetic modeling of oxygen absorption by unsaturated esters and linseed oil to be used as oxygen scavengers / Modélisation cinétique des principes actifs à base de lipides non-saturés pour l'emballage actifGarcia, Angela 15 January 2016 (has links)
Les capteurs d’oxygène sont le plus grand apport dans la technologie des emballages actifs parce qu’ils permettent de retarder la dégradation oxydante des aliments et ainsi éviter la perte de saveurs et le développement microbien au sein des aliments. Bien que le développement des emballages actes existe depuis les années 70 dans des pays producteur agricole, la recherche sur ces emballages reste encore embryonnaire, en particulier sur les critères techniques portant sur l’absorption d’oxygène de films. Cette thèse constitue une contribution sur l’étude des cinétiques d’absorption d’oxygène de l’huile de lin comme capteur d’oxygène. L’oxydation de l’huile et d’esters insaturés (composé modèle de l’huile) est suivie sous différentes conditions d’exposition (températures comprises entre 40-110°C et pressions partielles d’oxygène entre 0 et 1 bar). Expérimentalement, on propose de caractériser l’absorption d’oxygène liée à l’oxydation de l’huile par thermogravimétrie (ATG), suivi de concentration d’oxygène et titrage de peroxide. Un modèle cinétique basé des schémas classiques avec décomposition des hydroperoxydes, est proposé pour simuler l’oxydation de l’huile de lin et des esters insaturés modèles. Ce modèle est ensuite extrapolé à des films de différentes épaisseurs de polypropylène (PP) contenant 1% d’huile de lin en considérant que cette dernière est bien dispersé dans la matrice PP et que la diffusion d’oxygène est pilotée par la matrice PP. / Oxygen scavengers (OS) are one of the most important technology of active packaging, because prevents oxidative degradation related with off-flavours, off-odours and microbial growth in food. Although active packaging has been proposed since 1970s, in developing countries with a large agricultural base, active packaging still remains unexplored both in terms of application and research, there is a lack of technical criteria on O2 scavenging films, labels, sheets, and trays. This PhD thesis is a contribution in the study of linseed oil as active ingredient for OS providing a kinetic characterization of its thermo-oxidation between 40°C and 110°C in atmospheres with different oxygen concentration. In the experimental approach, innovative application of TGA was proposed to study oxygen uptake capacity complemented by headspace and peroxide value measurements. The kinetic model, derived from a classic mechanistic scheme where initiation of thermo-oxidation results from decomposition of hydroperoxides, was capable to simulated linseed oil oxidation, and also oxygen absorptions of polypropylene films, of different thickness, containing 1% of linseed oil, with hypotheses of well dispersion of linseed oil in PP matrix, and oxygen diffusion governed by the PP matrix.
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EFEITO DE Paullinia cupana (Mart.) NO ESTRESSE OXIDATIVO INDUZIDO PELO NITROPRUSSIATO DE SÓDIO EM CELÚLAS DE FIBROBLASTOS EMBRIONÁRIOS NIH-3T3 / Paullinia cupana (Mart.) EFFECT ON OXIDATIVE STRESS SODIUM NITROPRUSSIDE INDUCED IN EMBRYONIC FIBROBLAST NIH-3T3 CELLSBittencourt, Leonardo da Silva 25 April 2011 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The antioxidant effects of the hydro-alcoholic guaraná extracts (Paullinia cupana var. sorbilis
Mart.) on nitric oxide (NO ) and other compounds generated from degradation of Sodium
Nitroprusside (SNP) in embryonic fibroblast culture (NIH-3T3 cells) were evaluated. The
guaraná bioactive compounds were initially determined by a high-performance liquid
chromatography (HPLC): caffeine=12.240 mg/g, theobromine=6.733 mg/g and total
catechins= 4.336 mg/g. To the experiments, initially the cells were grown in DMEM
(Dulbecco s Modified Eagle Medium) medium and incubated in a humidified atmosphere of
5% CO2 and 37°C until reach 90% confluence. Cell cultures were exposed to 10μM SNP
during six hours since in this concentration the cells present >90% mortality. Guaraná diluted
in water was added in the cultures in five concentrations (0.5, 1, 5, 10 and 20 mg/mL). MTT
and Trypan blue viability, biochemical oxidative markers and genotoxicity (DNA Comet
assay) analysis were performed. Additionally, the cell oxidative stress was evaluated by 2,7
dihydrodichlorofluorescein diacetate (DCFDA) fluorescence assay by confocal microscopy.
Guaraná reverted the SNP toxicity mainly in lower concentrations (<5 mg) decreasing cell
mortality, lipid peroxidation, DNA damage and cell oxidative stress and increasing the SOD
levels. However, guarana was unable to reverse the inhibition of catalase probably triggered
by the presence of cyanide which is also produced in the decomposition of SNP. The results
suggest that guarana has effects on the modulation of excessive amounts of NO probably
through its antioxidant properties. These results supported previous studies that suggest
guarana have a protective effect against morbidity as obesity and metabolic syndrome that
are related to metabolism. / Os efeitos antioxidantes do extrato hidro-alcoólico de guaraná (Paullinia cupana var. sorbilis)
sobre o Óxido Nítrico (NO ) e outros compostos gerados a partir da decomposição do
Nitroprussiato de Sódio (NPS) em cultura de fibroblastos embriônicos (NIH 3T3) foram
avaliados. Os compostos bioativos do guaraná foram inicialmente determinados por
cromatografia líquida de alta performance (HPLC): cafeína=12,240 mg/g, teobromina=6,733
mg/g e catequinas totais=4,336 mg/g. Para os experimentos as células foram inicialmente
cultivadas em meio DMEM (Dulbecco s Modified Eagle Medium) e incubadas em uma
atmosfera umidificada de 5% de CO2 a 37°C até chegar a uma confluência de 90%. As
culturas de células foram expostas ao NPS na concentração de 10μM durante seis horas.
Nesta concentração de NPS e tempo de exposição ocorre uma taxa de mortalidade celular
>90%. O guaraná diluído em água foi adicionado em cinco diferentes concentrações (0,5, 1,
5, 10 e 20 mg/mL). Os ensaios de viabilidade MTT e azul de tripan, de marcadores
bioquímicos de estresse oxidativo e genotoxicidade (ensaio cometa) foram realizados.
Adicionalmente, o estresse oxidativo celular foi avaliado através do ensaio da fluorescência
do diacetato de 2,7 diclorofluoresceína (DCFDA) via microscopia confocal. O guaraná
reverteu à toxicidade induzida pelo NPS principalmente em concentrações mais baixas
(<5mg/mL), diminuindo a: mortalidade celular, peroxidação lipídica, dano de DNA e
produção de espécies reativas a aumentou os níveis da enzima Super Óxido Dismutase
(SOD). Entretanto, o guaraná não conseguiu reverter a inibição da catalase provavelmente
desencadeada pela presença de cianeto que também são produzidos na decomposição do
NPS. Os resultados sugerem que o guaraná tem efeitos na modulação das quantidades
excessivas de NO provavelmente através de suas propriedades antioxidantes. Estes
resultados confirmaram estudos prévios que sugerem que o guaraná tem efeito protetor
contra morbidades como obesidade e síndrome metabólica que são relacionadas ao
metabolismo.
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\"Coleta seletiva solidária: desafios no caminho da retórica à prática sustentável\" / Coleta Seletiva Solidária: challenges on the way between rhetorical and sustainable practiceMariana Vieira Viveiros 24 August 2006 (has links)
O programa Coleta Seletiva Solidária, iniciado em 2003 pela Prefeitura de São Paulo e que prevê a realização da coleta seletiva domiciliar na cidade por meio de cooperativas de ex-catadores de materiais recicláveis subsidiadas pelo poder público, é sustentável em termos econômicos, sociais e ambientais? Embora a retórica em que se baseia esteja em sintonia com a matriz discursiva da sustentabilidade urbana - de uma forma geral e aplicada ao lixo - e com os preceitos da economia solidária, a iniciativa dispõe dos elementos e consegue alcançar os resultados que, na prática, podem garantir a sua manutenção como política pública? Para tentar responder essas duas perguntas, este trabalho se valeu da aplicação de indicadores de sustentabilidade para programas municipais de coleta seletiva em parceria com ex-catadores e para as organizações neles envolvidas, elaborados pelo grupo de trabalho Coselix, financiado pela Funasa (Fundação Nacional da Saúde). A partir dos resultados obtidos, e tendo como pano de fundo um referencial teórico que mostra como as políticas públicas ambientais devem buscar a mudança institucional para serem eficientes em seus propósitos de aproximar o ideal do desenvolvimento sustentável da realidade, chega-se à conclusão de que a Coleta Seletiva Solidária tem grau de sustentabilidade apenas médio, comprometido sobretudo por deficiências institucionais, que se refletem numa baixa eficiência socioambiental (baixa cobertura, média recuperação de materiais recicláveis e alto índice de rejeito) e no fato de as cooperativas que integram o programa também se mostrarem, via de regra, longe da sustentabilidade. Apesar disso, a iniciativa tem potencial, evidenciado principalmente por sua base legal clara, infra-estrutura bem montada e pelos ganhos sociais qualitativos obtidos em grande parte das cooperativas. / Is Coleta Seletiva Solidária, a municipal initiative which began in 2003 in the city of São Paulo and establishes that selective collection of household waste will be conducted by former scavengers organized in cooperatives, sustainable in economic, social and environmental terms? Although based in a rhetoric that seems in tunning with the discursive matrix of urban sustainability - in general and applied to waste issues -and with the concepts of solidary economy, does the project have the elements and can it achieve the results that, in practice, may grant its survival as a public policy? In an attempt to answer these questions, this dissertation turned to the application of sustainability indicators specially developed to analyze and rank municipal selective collection programs with former scavengers and the organizations involved in such initiatives, created by the work group Coselix, financed by Funasa (Fundação Nacional da Saúde). Based on the results obtained and having as framework theoretical references which point how environmental public policies must aim at institutional change in order to reach their goals and bring the sustainable development ideal closer to reality, it concludes that Coleta Seletiva Solidária has only a medium sustainability degree, compromised mainly by institutional flaws, that are reflected in a lack of socioenvironmental efficiency (small coverage, medium recovery of recyclable goods and high reject rate) and in the fact that the cooperatives involved in the program are, in general, also far from sustainability. However, the initiative shows potential especially when it comes to its legal base, to a well constructed infrastructure and to the qualitative social gains obtained in most of the cooperatives.
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Bases moléculaires du polymorphisme de compatibilité dans l'interaction Schistosoma mansoni / Biomphalaria glabrataMoné, Yves 15 March 2011 (has links) (PDF)
La dynamique co-évolutive qui joue dans les systèmes hôte-parasite conduit à une véritable course aux armements entre les deux protagonistes qui se traduit, dans certaines interactions comme celle qui est traitée dans cette thèse, par un polymorphisme de compatibilité dont les bases moléculaires sont méconnues. L'objectif de cette thèse était de progresser dans la connaissance des mécanismes moléculaires sous-jacents à ce polymorphisme de compatibilité dans l'interaction Biomphalaria glabrata/Schistosoma mansoni. Une approche protéomique comparative entre des souches de parasites compatibles et incompatibles nous a permis d'identifier des déterminants moléculaires clés de l'interaction exprimés par le parasite. Il s'agit d'une part de mucines hautement polymorphes potentiellement antigéniques, les "Schistosoma mansoni Polymorphic Mucin" (SmPoMucs), et d'autre part de molécules anti-oxydantes ("ROS scavengers"). Afin d'aborder la question de la course aux armements de manière complète, nous avons également recherché la "contre-partie moléculaire" exprimée par le mollusque et susceptible d'exprimer ce polymorphisme de compatibilité. Dans ce but, des approches de co-précipitation ont été menées. Elles ont permis de montrer que les SmPoMucs interagissaient avec des récepteurs immunitaires diversifiés du mollusque, les Fibrinogen-related Proteins (FREPs). Nous montrons ainsi pour la première fois dans une interaction parasite/hôte invertébré l'intervention d'un "système de type antigène-anticorps" impliquant un répertoire individuel polymorphe d'antigènes potentiels du parasite (les SmPoMucs) et un répertoire individuel diversifié de récepteurs immunitaires de son hôte (les FREPs). Nous avons également montré que le complexe immun formé par les deux dernières molécules citées incluait un troisième partenaire, une thioester-containing protein (TEP) qui appartient à une classe de molécules connue pour son rôle dans la fagocytose ou l'encapsulation. La présence de ce troisième partenaire au sein d'un même complexe renforce le rôle potentiellement immunitaire de ce complexe dans la reconnaissance et l'élimination du parasite. Au travers de cette thèse, nous nous sommes également intéressés à la course aux armements jouant sur les mécanismes effecteurs de l'immunité du mollusque. Dans notre modèle, les effecteurs responsables de la destruction du parasite sont principalement des espèces réactives de l'oxygène (ROS). Dans ce cas aussi, nous avons montré qu'il existe une concordance phénotypique entre la production de ROS par l'hôte et le niveau de "ROS scavengers" produits par le parasite pour contrecarrer la réaction de l'hôte. Ainsi, les mécanismes moléculaires responsables du polymorphisme de compatibilité dans l'interaction B. glabrata/S. mansoni s'appuieraient au moins sur deux facteurs d'une part sur la confrontation de répertoires de molécules polymorphes et/ou diversifiées en ce qui concerne les mécanismes de reconnaissance immunitaire, et d'autre part sur une adaptation réciproque quantitative en ce qui concerne certains mécanismes effecteurs de l'immunité.
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Synthetic Antioxidants : Structure-Activity Correlation Studies Of Glutathione Peroxidase Mimics And Peroxynitrite ScavengersBhabak, Krishna Pada 07 1900 (has links)
Reactive oxygen species (ROS) such as superoxide radical anion (O2•¯), hydroxylradical (OH•), hydrogen peroxide (H2O2) and peroxynitrite (ONOO-) that are produced during the metabolism of oxygen under oxidative stress in aerobic organisms destroy several key biomolecules and lead to a number of disease states. Mammalian systems possess several effective defense mechanisms including antioxidant enzymes to detoxify these ROS. The selenocysteine-containing Glutathione peroxidase (GPx) is particularly an efficient enzyme in the detoxification of H2O2 and other hydroperoxides by using glutathione (GSH) as cofactor. The chemistry at the active siteof GPx has been extensively investigated with the help of synthetic selenium compounds. Although the anti-inflammatory compound ebselen(2-phenyl-1,2-benzoisoselenazol-3(2H)-one) is undergoing phase III clinical trial as antioxidant, the chemistry of ebselen is still not understood.
The present study on a number of ebselen derivatives with various N-substitutions reveals that the substitution at the N atom is important for the antioxidant activity. This study also suggests that the nature for thiol cofactor has a dramatic effect on the GPx activity of ebselen derivatives. It has been shown that ebselen exhibits very poor catalytic activity in the presence of aromatic thiols mainly due to strong Se….O nonbonded interactions that lead to extensive thiol exchange reactions in the selenenyl sulfide intermediate. To prevent the se….O interactions, a series of tertiary amide-based diselenides have been synthesized along with their secondary amide counterparts.
Detailed structure-activity correlation studies reveal that the GPx-like activity of the sec-amide-based compounds can be significantly enhanced by the substitution at the free-NH group of sec-amide functionality. The N,N-dialkylbenzylamine-based diselenides exhibit their catalytic activities via the generation of selenols which was confirmed by the reaction with anti-arthritic gold(I) compounds. Interestingly, the replacement of the hydrogen atom at the 6th position of the benzene ring of N,N-dialkylbenzylamine-based diselenides by a methoxy group prevents the thiol exchange reactions mainly be weakening the Se…N interactions and thus enhances the GPx activity. On the other hand, the catalytic activity of the tert-amine-based diselenides can also be increased by replacing the tert-amino groups with the corresponding sec-amine moieties. It has been observed that the basic amino group in the amine-based diselenides deprotonates the selenol and also the thiol cofactor, which is crucial for the higher catalytic activities of the amine-based compounds.
Peroxynitrite (PN, ONOO), a strong nitrating agent, is known to inactivate a number of proteins, enzymes and other biomolecules by nitration of tyrosine residues. In this study, we have shown that the commonly used antithyroid drugs and their analogues inhibit protein tyrosine nitration. This study reveals that antithyroid agents having PN scavenging activity may be beneficial of hyperthyroidism as these compounds may protect the thyroid gland from nitrative or nitrosative stress.
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Identificação de oportunidades de Produção Mais Limpa em uma cooperativa de reciclagem de plásticos na cidade de Sorocaba-SP / Identification of Cleaner |Production opportunities in a plastic recycling coperative in the city of Sorocaba-SPSantos, Fábio Ferreira 21 March 2017 (has links)
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Previous issue date: 2017-03-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Waste generation is a global challenge to be faced, especially in industrializing countries such as Brazil, where high waste generation in line with structural problems and inadequate waste management can result in environmental, economic and social problems. Thus, recycling can be considered as an important strategy to face this challenge in order to develop practices focused on the triple bottom line (sustainability). The recycling chain in Brazil is considered complex involving multiple actors, among them we can highlight the activities of scavengers as fundamental agents on viability of recycling. However, the scavengers are not always recognized, they are the ones that benefit least in the chain and they face several difficulties. In seeking to overcome the difficulties and achieve better positioning in the chain, scavengers have organized into cooperatives, networks and materials processing centers. From the environmental point of view, recycling processes, especially of post-consumer plastics, can also have an impact on the environment, if management is not established from the collection until the final disposal of the same. It is therefore important to adopt environmental management tools such as Cleaner Production (CP), for example, that result in benefits to the environment, society and organizations. This research aimed to identify opportunities for improvement in plastics recycling process in a cooperative of Sorocaba-SP, through the use of the CP tool. The research consisted of a case study in a cooperative that performs the recycling process of Polyethylene (PE) and Polypropylene (PP), transforming them into flakes and / or pellets. The steps of the CP adopted in this research were based on the Centro Nacional de Tecnologias Limpas (CNTL, 2003) and complemented by SEBRAE guidelines (2005) and by the study of Silva et al. (2013). The following steps were carried out: awareness and general characterization of the cooperative, mapping of the recycling process, quantification of input and output streams, definition of indicators, selection of the evaluation focus, identification of causes of waste generation, effluents and emissions, and identification of CP opportunities. The study revealed that the recycling process of the cooperative is passive to generate environmental impacts, mainly due to the lack of standardization of the raw material and the high consumption of water in the washing stage and consequent generation of effluents. 25 improvement opportunities were identified, focusing mainly on level 1 of housekeeping. In addition, barriers to CP in the cooperative were identified, especially those related to financial issues and lack of government support. Thus, it is necessary to overcome these barriers to an effective implementation of the CP and obtain the consequent economic, environmental and social benefits. / A geração de resíduos é um desafio mundial a ser enfrentado, principalmente nos países em processo de industrialização como o Brasil, no qual a alta geração de resíduos alinhada aos problemas estruturais de gestão e descartes inadequados podem ocasionar problemas ambientais, econômicos e sociais. Assim, a reciclagem pode ser considerada como uma importante estratégia para se enfrentar este desafio com o objetivo de desenvolver práticas voltadas para o tripé da sustentabilidade. A cadeia de reciclagem no Brasil é considerada complexa por envolver múltiplos atores, dentre eles, podem-se destacar a atuação dos catadores como agentes fundamentais na viabilização da reciclagem. No entanto, os catadores nem sempre são reconhecidos, são os que menos se beneficiam na cadeia e enfrentam várias dificuldades. Na busca por superar as dificuldades e obter um melhor posicionamento na cadeia, os catadores têm-se organizado em cooperativas, redes e centros de processamento de materiais. Sob o ponto de vista ambiental, os processos de reciclagem, principalmente dos plásticos oriundos do pós-consumo, também podem ocasionar impactos ao meio ambiente, caso não se estabeleça uma gestão desde a coleta até a destinação final dos mesmos. Assim, é importante a adoção de ferramentas de gestão ambiental como a Produção Mais Limpa (P+L), por exemplo, que resulte em benefícios ao meio ambiente, a sociedade e as organizações. Esta pesquisa objetivou identificar oportunidades de melhorias no processo de reciclagem dos plásticos em uma cooperativa de Sorocaba – SP, por meio da utilização da ferramenta P+L. A pesquisa consistiu em um estudo de caso em uma cooperativa que realiza o processo de reciclagem do Polietileno (PE) e Polipropileno (PP), transformando-os em flakes (fragmentos) e/ou pellets (grânulos). As etapas da P+L adotadas nesta pesquisa foram baseadas no Centro Nacional de Tecnologias Limpas (CNTL, 2003) e complementada pelas orientações do SEBRAE (2005) e pelo estudo de Silva et al. (2013). Assim realizaram-se as seguintes etapas: sensibilização e caracterização geral da cooperativa, mapeamento do processo de reciclagem, quantificação das correntes de entradas e saídas, definição de indicadores, seleção do foco de avaliação, identificação das causas de geração de resíduos, efluentes e emissões, e identificação de oportunidades de P+L. O estudo revelou que o processo de reciclagem da cooperativa é passivo de gerar impactos ambientais, devido principalmente a ausência de padronização da matéria-prima e o alto consumo de água na etapa de lavagem e consequente geração de efluentes. Foram identificadas 26 oportunidades de melhorias, em sua maioria classificadas no nível 1 da P+L (housekeeping). Além disso, foram identificadas barreiras de P+L na cooperativa, principalmente as relacionadas às questões financeiras e ausência de apoio governamental. Assim, foi constatado a necessidade de superar essas barreiras para uma efetiva implementação da P+L e obter os consequentes benefícios econômicos, ambientais e sociais.
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Os novos paradigmas na política nacional de resíduos sólidos e os desafios do programa de coleta sustentável em João Pessoa / The new paradigm in national policy of solid waste and the challenges of the program of sustainable collection in Joao PessoaSoares, Rodrigo de Sousa 31 March 2014 (has links)
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Previous issue date: 2014-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Study of the concepts, goals, deadlines and relevant instruments to Law 12.305 of 2010 that establishes the National Policy of Solid Waste ( PNRS ) in Brazil and its application, considering the challenges to consolidate a new reality of sustainable growth from the production of less waste, either in the manufacturing process or even in domestic consumption , extending the life cycle of products and allowing the country to definitely assume a sustainable development agenda. Assuming that the implementation of this Public Environmental Policy can mean the realization of new paradigms of development with sustainability as advocates Agenda 21, it has been sought beneath the perspective of economic law to highlight the legal implications from the concepts of the State of Social Welfare and Sustainable Development in Brazil. The legislation analysis indicates the importance of the principles of precaution and prevention within the framework of legal protection and the sharing of responsibilities in environmental management. Taking as parameter the management and implementation of PNRS in João Pessoa -PB and the experience in Brazil of selective collection with scavengers of recycled material. The local collection program and the challenges to have a sustainable collection program has been described, which facilitates the full operation of the reverse logistics and selective collection systems with social and economic inclusion of the scavengers of recycled material and the application of sectoral agreements and responsability pos - demand, causing a change in patterns of production and consumption . / Estudo dos conceitos, metas, prazos e instrumentos pertinentes a Lei 12.305 de 2010 que institui a Política Nacional de Resíduos Sólidos (PNRS) no Brasil e da sua aplicação considerando os desafios para consolidar uma nova realidade de crescimento sustentável a partir da produção de menos resíduos, seja no processo industrial ou mesmo no consumo doméstico, ampliando o ciclo de vida dos produtos e permitindo ao país assumir definitivamente uma agenda de desenvolvimento sustentável. Partindo da premissa que a implantação dessa Política Pública Ambiental pode significar a concretização de novos paradigmas de desenvolvimento com sustentabilidade como preconiza a Agenda 21 , buscou-se sob a ótica do Direito Econômico destacar as implicações jurídicas a partir dos conceitos do Estado de Bem Estar Social e de Desenvolvimento Sustentável no Brasil. A análise da legislação indica a importância dos princípios da precaução e da prevenção no âmbito da proteção jurídica e do compartilhamento de responsabilidades na gestão ambiental. Tomando como parâmetro a gestão e aplicação da PNRS no município de João Pessoa-PB e a experiência no Brasil da coleta seletiva com os catadores de material reciclado. Descrito o programa local de coleta e os desafios para um programa de coleta sustentável, que viabilize o pleno funcionamento dos sistemas de logística reversa e coleta seletiva com a inclusão socioeconômica dos catadores de materiais recicláveis e a aplicação dos acordos setoriais e da responsabilidade pós-consumo, provocando uma mudança nos padrões de produção e consumo.
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O espaço da cooperativa Amigos do Meio Ambiente : cooperativa de trabalho ou cooperfraude?. / The space of the cooperative "Friends of the Environment": cooperative of jobs or cooperfraude?Sterchile, Shirla Patricia Weber 28 July 2009 (has links)
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Previous issue date: 2009-07-28 / This project is constitutive of our professional practice as a social worker and of the formation process like mastering in the program of masters degree in Regional and Agrobusiness development. In this process we chose as the locus of this investigation the cooperative of the environmental agents from Santa Helena Friends of the Environment that the priory was seemed so common and known. We delimitaded as object the investigation the way of existing and being of the cooperative of environmental agents from Santa Helena Friends of the Environment and its imbrication at the Usine of improvement of solid waste from the borough of Santa Helena PR. Faced with the anxieties that guided the construction of the object here burst, forming from the initial contact in 2004 with the human scavengers of recycling materials from the borough of Santa Helena, We built up as the research problem: Do the innovators mechanism of theoretical and practical formulation present at the cooperative of the environmental agents from Santa Helena Friends of the Environment answer to the interests of the workers? . Watching the unhappiness of some human scavengers and the incentive of the municipal manager to the installation of the Usine and the formation of the Cooperative, allied with the postulates of capitalism, specially in its tarty phase we disbuilt and rebuilt the reality given from the research empiric. With this purpose, we define as the general aim: learn, understand and analyze the cooperative of work in the process of improvement of solid waste, in its concrete demonstration into the moviment of tardy capital in answers to the private determinations of the Capitalism in Brazil and its objectivation in the borough of Santa Helena. In base with boarding qualitative, having the case of study as the specific type of delimitation of the object and with the use of the bibliographic search, from the interview, of the documental analyze and of the observation, the search revealed the locus of this analyse. The investigated attitude allowed us to conclude that the Cooperative Friends of the Environment is treated of one cooperfradude , in which it is legitimized by the State, oblitarating the principles of the cooperativism and liberating the capital of the root of the exploration of the work power. The Cooperative mask the logical of the salaried, if acquitting the warranty of the rights socialy achieved by the workers, in whici they degraded in everyday fight throughout their survival. / Este trabalho é constitutivo do nosso exercício profissional como Assistente Social e do processo de formação como mestranda no Programa de Mestrado em Desenvolvimento Regional e Agronegócio. Neste processo, elegemos como lócus desta investigação a Cooperativa dos Agentes Ambientais de Santa Helena Amigos do Meio Ambiente que, a priori, nos parecia tão comum e conhecido. Delimitamos como objeto de análise A forma de existir e de ser da Cooperativa dos Agentes Ambientais de Santa Helena Amigos do Meio Ambiente e sua imbricação na Usina de Beneficiamento de Resíduos Sólidos do município de Santa Helena-PR. . Diante das angústias que nortearam a construção do objeto aqui deflagrado, que se formaram a partir do contato inicial em 2004 com os catadores de materiais recicláveis do município de Santa Helena-PR, construímos como problema de pesquisa: Os inovadores mecanismos de formulação teórica e prática presentes na Cooperativa dos Agentes Ambientais de Santa Helena Amigos do Meio Ambiente respondem aos interesses dos trabalhadores? . Observando o descontentamento de alguns catadores e o incentivo do gestor municipal para a instalação da Usina e a formação da Cooperativa, aliado aos postulados do capitalismo, principalmente em sua fase tardia, entendemos relevante desconstruir e reconstruir esta realidade a partir da pesquisa empírica. Com este propósito, definimos como objetivo Apreender, compreender e analisar a cooperativa de trabalho no processo de beneficiamento de resíduos sólidos, em sua manifestação concreta no movimento do capital tardio em resposta as determinações particulares do capitalismo no Brasil e sua objetivação no município de Santa Helena . Com base na abordagem qualitativa, tendo o estudo de caso como tipo específico de delimitação do objeto e com a utilização da pesquisa bibliográfica, da entrevista, da análise documental e da observação, a pesquisa desvelou o lócus desta análise. A atitude investigativa nos permitiu concluir que a Cooperativa Amigos do Meio Ambiente trata-se de uma cooperfradude , a qual é legitimada pelo Estado, suprimindo os princípios do cooperativismo e eximindo o capital da raiz da exploração da força de trabalho. A Cooperativa mascara a lógica do assalariamento, se isentando da garantia de direitos socialmente conquistados pelos trabalhadores, os quais se degradam na luta cotidiana pela sobrevivência.
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Synthèse et purification de matériaux à caractère cristal liquide à base de triphénylène pour leur utilisation dans des diodes électroluminescentes organiquesRoussel, Olivier 07 September 2006 (has links)
Les diodes électroluminescentes organiques (OLED) ont une durée de vie limitée. Cette limitation est notamment due à la présence d'impuretés dans le matériau électroluminescent. Ces impuretés proviennent principalement des électrodes. Nous pensons que l'ajout de couches de matériaux entre les électrodes et le matériau électroluminescent peut retarder l'arrivée des impuretés. Cette couche ajoutée doit avoir plusieurs caractéristiques dont principalement :être conductrice, ne pas absorber la lumière, être facilement mise en oeuvre et être d'une grande pureté. Nous pensons que des matériaux de type discotique possédant une mésophase aux températures d'utilisation de la OLED peuvent remplir ce cahier des charges.<p>Nous avons choisi d'étudier les composés discotiques à base de triphénylène, car celui-ci n'absorbe pas dans le visible. Nous avons tout d'abord étudié les 2,3,6,7,10,11-Hexa-(alkylthio)triphénylènes (HATT). Les HATT possèdent déjà les propriétés physiques que nous recherchons à l'exception des propriétés thermotropes. Nous avons donc étudié la possibilité de modifier celles-ci.<p>La synthèse de plusieurs HATT possédant six chaînes alkylsulfanyles identiques n'a pas donné les résultats attendus du point de vue des propriétés thermotropes. Nous avons alors synthétisé des molécules possédant plusieurs chaînes alkylsulfanyles différentes. Après différents essais, nous avons trouvé un mélange de molécules possédant plusieurs chaînes latérales différentes ayant les propriétés physiques recherchées. Mais ce matériau est composé d'un grand nombre de molécules et sa purification est difficile. Les techniques classiques de purification des composés organiques ne donnant pas une pureté suffisante, ou étant inapplicables sur une mésophase cristal liquide à température ambiante, nous avons donc recherché d'autres techniques de purification ou d'obtention des propriétés thermotropes désirées.<p> Nous avons étudié la purification par raffinage de zone des matériaux à l'aide d'une impureté que nous avons ajoutée et suivie au cours des manipulations. Le raffinage de zone montre une bonne purification lors de l'utilisation d'une transition de phase entre une phase cristalline et une phase liquide. Par contre, lors de l'utilisation d'une transition impliquant une mésophase (cristal liquide ou cristal plastique), une faible (ou une absence de) purification est observée. Ces deux dernières études ont été faites sur des 2,3,6,7,10,11-Hexa(alkyloxy)triphénylènes (HAOT) que nous avons synthétisés et purifiés au préalable. <p>Les gels de silice fonctionnalisés que nous avons utilisés montrent une purification des cations métalliques durs et, dans une moindre mesure, des cations métalliques intermédiaires dans le concept dur-mou. Le phosphore, seul élément non-métallique que nous ayons étudié, est l'élément dont la baisse de concentration est la moins efficace.<p>La seconde approche pour obtenir des mélanges possédant une mésophase cristal liquide à température ambiante est la formation de mélanges de molécules synthétisées et purifiées isolément. Parmi les mélanges de molécules que nous avons effectués, nous avons pu observer une plage de concentration de mélanges ternaires qui possède les propriétés thermotropes recherchées.<p>Nous avons donc obtenu un matériau cristal liquide à température ambiante grâce à un mélange de molécules. Le matériau ainsi formé absorbe peu dans le visible, possède potentiellement une bonne mobilité des porteurs de charges électriques, est facilement obtenu à une pureté suffisante. Ce mélange de molécules possède donc les propriétés que nous recherchons pour être utilisé comme couche de matériau ajoutée aux OLED.<p> / Doctorat en sciences, Spécialisation chimie / info:eu-repo/semantics/nonPublished
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The Behavior Of Cerium Oxide Nanoparticles In Polymer Electrolyte Membranes In Ex-situ And In-situ Fuel Cell Durability TestsPearman, Benjamin 01 January 2012 (has links)
Fuel cells are known for their high efficiency and have the potential to become a major technology for producing clean energy, especially when the fuel, e.g. hydrogen, is produced from renewable energy sources such as wind or solar. Currently, the two main obstacles to wide-spread commercialization are their high cost and the short operational lifetime of certain components. Polymer electrolyte membrane (PEM) fuel cells have been a focus of attention in recent years, due to their use of hydrogen as a fuel, their comparatively low operating temperature and flexibility for use in both stationary and portable (automotive) applications. Perfluorosulfonic acid membranes are the leading ionomers for use in PEM hydrogen fuel cells. They combine essential qualities, such as high mechanical and thermal stability, with high proton conductivity. However, they are expensive and currently show insufficient chemical stability towards radicals formed during fuel cell operation, resulting in degradation that leads to premature failure. The incorporation of durability improving additives into perfluorosulfonic acid membranes is discussed in this work. iv Cerium oxide (ceria) is a well-known radical scavenger that has been used in the biological and medical field. It is able to quench radicals by facilely switching between its Ce(III) and Ce(IV) oxidation states. In this work, cerium oxide nanoparticles were added to perfluorosulfonic acid membranes and subjected to ex-situ and in-situ accelerated durability tests. The two ceria formulations, an in-house synthesized and commercially available material, were found to consist of crystalline particles of 2 – 5 nm and 20 – 150 nm size, respectively, that did not change size or shape when incorporated into the membranes. At higher temperature and relative humidity in gas flowing conditions, ceria in membranes is found to be reduced to its ionic form by virtue of the acidic environment. In ex-situ Fenton testing, the inclusion of ceria into membranes reduced the emission of fluoride, a strong indicator of degradation, by an order of magnitude with both liquid and gaseous hydrogen peroxide. In open-circuit voltage (OCV) hold fuel cell testing, ceria improved durability, as measured by several parameters such as OCV decay rate, fluoride emission and cell performance, over several hundred hours and influenced the formation of the platinum band typically found after durability testing.
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