1,238 research outputs found

    Dimethyl adipate hydrogenation at presence of Pt and Pd based catalysts

    Get PDF
    Orientadores: Elizabete Jordão, Wagner Alves CarvalhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuimicaResumo: A hidrogenação do adipato de dimetila catalisada por Pt e por Pd foi avaliada. Os catalisadores foram suportados em alumina, titânia e carvão. Os parâmetros investigados foram: a influência do suporte, a influência do metal ativo Pd quando comparado com Pt e a influência dos promotores Sn e K em alguns catalisadores. A caracterização físico-química dos sistemas catalíticos foi feita por Fisissorção de 'N IND. 2¿ ¿ BET, Quimissorção de 'H IND. 2¿, Microscopia Eletrônica de Varredura ¿ MEV, Redução a Temperatura Programada ¿ TPR e Espectrometria de Emissão Ótica em Plasma Indutivamente Acoplado ¿ ICP OES. A dispersão dos metais nos catalisadores mostrou-se diretamente relacionada à área superficial dos suportes, sendo que partículas bimetálicas ou parcialmente cobertas (no caso da titânia) podem estar presentes. O suporte altera o comportamento dos metais presentes na sua superfície por diferentes maneiras: efeito SMSI (titânia), acidez (aluminia) e presença de grupos funcionais oxidados (carvão). A conversão de adipato de dimetila á reduzida na presença do suporte titânia e aumenta quando o suporte é alumina, o que está relacionado à acidez deste, com a formação de uma elevada quantidade de produtos indesejáveis. Maiores valores de seletividade para a produção de 1,6 ¿ hexanodiol são observados com o uso de titânia, uma vez que espécies parcialmente reduzidas do suporte favorecem a ativação da carbonila do substrato ...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digitalAbstract: The hidrogenation of dimethyl adipate catalyzed by Pt and Pd was evaluated. The catalysts were supported in 'Al IND. 2¿¿O IND. 3¿, 'TiO IND. 2¿ and coal. The investigated parameters were: the influence of the support, the influence of the active metal Pd when compared to Pt and the influence of Sn and K as promoters in some catalysts. The physical-chemistry characterization of the catalytic system was made by 'N IND. 2¿ sorption ¿ BET, 'H IND. 2¿ soption, Scanning Electron Microscopy ¿ SEM, Temperature Programmed Reduction ¿ TPR and Inductively coupled Plasma Optics Emission superficial area of the supports, and bimetallic particles or partially covered (in the case of the 'TiO IND. 2¿) can be present. Support modifies the behavior of metals in the surface for different ways: SMSI effect ('TiO IND. 2¿), acidity ('Al IND. 2¿¿O IND. 3¿) and presence of oxidized functional groups (coal). The conversion of dimethyl adipate is reduced in the presence of 'TiO IND. 2¿ and increases when the support is 'Al IND. 2¿¿O IND. 3¿. This is related to the 'Al IND. 2¿¿O IND. 3¿ acidity, with the formation of many undersirable products. Higher selectivity values for the production of 1,6-hexaodiol are observed with 'TiO IND. 2¿, due to the partially reduced species of the support that favor the activation of the carbonyl...Note: The complete abstract is available with the full electronic digital thesis or dissertationsMestradoSistemas de Processos Quimicos e InformaticaMestre em Engenharia Químic

    Hydrogenation of dimethyl adipate at presence of pillared clay based catalysts

    Get PDF
    Orientadores: Elizabete Jordão, Wagner Alves CarvalhoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuimicaResumo: Vários métodos de síntese das argilas pilarizadas foram testados. Obtivemos os materiais pilarizados com alumínio em condições distintas: suspensões diluídas (Al-PILC 02), suspensões concentradas (Al-PILC 03), soluções pilarizantes concentradas (Al-PILC 04) e o uso de microondas no processo de envelhecimento (Al-PILC 05). Este último demonstrou ser o processo mais adequado, já que permitiu a obtenção da argila pilarizada em maior quantidade e menor tempo de síntese. As argilas pilarizadas apresentaram um significativo aumento na área superficial, principalmente relacionada aos microporos, e uma elevada capacidade de dispersão dos metais ativos platina e paládio. A exceção é o rutênio, que manteve a baixa dispersão já observada em outros suportes utilizados. A acidez dos suportes e catalisadores foi avaliada por diferentes técnicas, indicando que os materiais apresentam acidez de Brönsted e de Lewis. Esta acidez pode ser efetivamente reduzida por tratamento dos sólidos com bário, enquanto um tratamento com lítio se mostrou ineficaz. Os testes catalíticos de hidrogenação do adipato de dimetila demonstraram que todos os sistemas estudados apresentam uma elevada conversão, tipicamente superior a 95%, atribuída a uma atividade do suporte. Nos catalisadores monometálicos os valores de seletividade permanecem reduzidos. A redução da acidez, promovida por um tratamento com bário, é de fundamental importância. Os catalisadores tratados com bário reduziram em até 45% a formação de produtos indesejáveis. Os catalisadores bimetálicos Ru-Sn permitiram a obtenção de produtos em elevadas concentrações como, por exemplo, o ácido capróico, que atingiu a concentração de 120 mmol/L após 3 h de reação. A avaliação da distribuição de produtos nestas reações permitiu a proposição de rotas para a formação dos diversos produtos obtidos. Nesta proposição são identificadas as rotas favorecidas pela acidez do catalisador e pela presença de catalisadores bimetálicos, indicando que é possível direcionar o processo catalítico para certos produtos em função do controle de algumas propriedades do catalisador.Abstract: Several methods of synthesis of pillared clays were tested. We were able to obtained aluminum pillared clays in different conditions: diluted suspensions (Al- PILC 02), concentrated suspensions (Al-PILC 03), concentrated pillaring solutions (Al-PILC 04) and microwave assisted aging (Al-PILC 05). The latter proved to be the most appropriate process, since it allowed obtaining pillared clay in greater quantities and less time. Pillared clays showed a significant increase in surface area mainly that related to micropores and a high degree of dispersion of active metals, platinum and palladium. The exception is ruthenium, which has maintained the low dispersion observed in other support tested. The acidity of the supports and catalysts was evaluated by different techniques, indicating that these materials exhibit Brönsted and Lewis sites. This acidity can be effectively reduced by the solid treatment with barium, while lithium was ineffective. Dimethyl adipate catalytic hydrogenation showed that all systems studied promoted a high conversion, typically higher than 95%, attributed to support activity. Monometallic catalysts maintain lower selectivity values. The reduction of acidity, promoted by a barium treatment, is fundamental in order to enhance the selectivity. The catalysts treated with barium reduced by 45% the formation of by-products. Ru-Sn bimetallic catalysts allow the formation of main products in high concentrations, for example, caproic acid, which reached a concentration of 120 mmol/L after 3 h reaction time. The evaluation of the products distribution in these reactions led to the proposed route for the formation of various products. It was identified routes favored by the solids acidity and by the presence of bimetallic catalysts, indicating that it is possible to promote the catalytic process in order to obtain certain products depending on the control of some properties of the catalyst.DoutoradoSistemas de Processos Quimicos e InformaticaDoutor em Engenharia Químic

    PARÂMETROS NACIONAIS DE QUALIDADE PARA EDUCAÇÃO INFANTIL NO PROCESSO HISTÓRICO

    Get PDF
    No presente artigo analisamos os Parâmetros Nacionais de Qualidade para Educação Infantil produzido pelo Ministério da Educação para identificar, no processo histórico e nas contradições econômicas e sociais em que foi gerado, a concepção de formação humana apresentada. A documentação descortinada foi discutida de modo a evidenciar as articulações existentes entre a política brasileira para a qualidade na Educação Infantil, as diretrizes dos organismos internacionais e os estudos que relacionam linearmente esta etapa da educação com inclusão e coesão social. Apresentamos os fundamentos da pedagogia histórico-crítica para a Educação Infantil e sua concepção de homem como singularidade e coletividade. Os resultados obtidos apontam para a necessidade de que se analise o conceito de qualidade na Educação Infantil para além dos discursos que disseminam uma visão de formação baseada no espontaneísmo e no relativismo

    The Subgingival Periodontal Microbiota in the Aging Mouth

    Get PDF
    Different mechanisms have been hypothesized to explain the increase in prevalence and severity of periodontitis in older adults, including shifts in the periodontal microbiota. However, the actual impact of aging in the composition of subgingival biofilms remains unclear. In the present article, we provide an overview of the composition of the subgingival biofilm in older adults and the potential effects of age on the oral microbiome. In particular, this review covers the following topics: (i) the oral microbiota of an aging mouth, (ii) the effects of age and time on the human oral microbiome, (iii) the potential impact of inflammaging and immunosenescence in the host-oral microbiota interactions, and (iv) the relationship of the aging oral microbiota and Alzheimer’s disease. Finally, in order to explore in greater breadth the potential effects of aging on the periodontal microbiota, we present analyses of data compiled from large clinical studies that evaluated the subgingival microbiota of periodontally healthy subjects and periodontitis patients from a wide age spectrum (20–83 years old). Those studies were conducted at Guarulhos University (São Paulo, SP, Brazil) and at The Forsyth Institute (Cambridge, USA), from 1999 to 2014

    A obrigatoriedade da pré-escola no contexto das parcerias público-privadas

    Get PDF
    Neste texto teve-se como finalidade analisar a obrigatoriedade da pré-escola no Brasil (Lei n. 12.796/2013) e a sua relação com o aprofundamento da participação dos organismos internacionais e do empresariado “socialmente responsável” como formulador de estratégias de implementação de políticas educacionais na Educação Infantil. O percurso metodológico da pesquisa compreendeu análise documental e reconstrução histórica com base na análise crítica marxista que situa o tema estudado no processo de luta de classes. Os resultados mostraram que as parcerias público-privadas na Educação Infantil estão em processo de expansão e fortalecimento, relacionando eficiência dos gastos sociais e investimento na primeira infância. Assim, com argumentos advindos de economistas e de neurocientistas de empresas privadas “socialmente responsáveis”, a Educação Infantil poderia ser resumida a uma etapa da educação que visa ao sucesso escolar no futuro ou a uma forma de se evitar possíveis riscos sociais consequentes da situação de iniquidade social a que as crianças estão expostas

    The subgingival periodontal microbiota of the aging mouth

    Get PDF
    Different mechanisms have been hypothesized to explain the increase in prevalence and severity of periodontitis in older adults, including shifts in the periodontal microbiota. However, the actual impact of aging in the composition of subgingival biofilms remains unclear. In the present article, we provide an overview of the composition of the subgingival biofilm in older adults and the potential effects of age on the oral microbiome. In particular, this review covers the following topics: (i) the oral microbiota of an aging mouth, (ii) the effects of age and time on the human oral microbiome, (iii) the potential impact of inflammaging and immunosenescence in the host-oral microbiota interactions, and (iv) the relationship of the aging oral microbiota and Alzheimer’s disease. Finally, in order to explore in greater breadth the potential effects of aging on the periodontal microbiota, we present analyses of data compiled from large clinical studies that evaluated the subgingival microbiota of periodontally healthy subjects and periodontitis patients from a wide age spectrum (20–83 years old). Those studies were conducted at Guarulhos University (São Paulo, SP, Brazil) and at The Forsyth Institute (Cambridge, USA), from 1999 to 2014

    Production of Pure Drug Nanocrystals and Nano Co-crystals by Confinement Methods

    Get PDF
    The use of drug nanocrystals in the drug formulation is increasing due to the large number of poorly water-soluble drug compounds synthetized and due to the advantages brought by the nanonization process. The downsizing processes are done using a top-down approach (milling and homogenization currently employed at the industrial level), while the crystallization process is performed by bottom-up techniques (e.g., antisolvent precipitation to the use of supercritical fluids or spray and freeze drying). In addition, the production of nanocrystals in confined environment can be achieved within microfluidics channels. This review analyzes the processes for the preparation of nanocrystals and co-crystals, divided by top-down and bottom-up approaches, together with their combinations. The combination of both strategies merges the favorable features of each process and avoids the disadvantages of single processes. Overall, the applicability of drug nanocrystals is highlighted by the widespread research on the production processes at the engineering, pharmaceutical, and nanotechnology level.Peer reviewe

    Levels of Selenomonas Species in Generalized Aggressive Periodontitis

    Get PDF
    Aim To compare the levels of Selenomonas sputigena and uncultivated/unrecognized Selenomonas species in subgingival biofilms from generalized aggressive periodontitis (GAgP) and periodontaly healthy (PH) subjects. Material and Methods GAgP (n=15) and PH (n=15) subjects were recruited and their clinical periodontal parameters were evaluated. Subgingival plaque samples were collected (9 samples/subject) and analyzed for the levels of 10 bacterial taxa, including cultivated and uncultivated/unrecognized microorganisms using the RNA-oligonucleotide quantification technique (ROQT). Differences in the levels of the test taxa between groups were sought using the Mann-Whitney test. Results GAgP subjects showed significantly higher mean counts of Porphyromonas gingivalis, Selenomonas sputigena and Selenomonas oral clone CS002 (Human Oral Microbial Database (HOMD) Oral Taxon 131), while Actinomyces gerencseriae and Streptococcus sanguinis were found in higher mean counts in PH subjects (pSelenomonas EW084 (HOMD OT 146) was only detected in the GAgP group. In the GAgP group, levels of P. gingivalis and S. sputigena were higher in sites with probing depth (PD) ≥5mm than in shallow sites (PD ≤3mm) (pP. gingivalis (r=0.77; pS. sputigena (r=0.60; pSelenomonas sp. EW076 (OT 139) (r=042, p\u3c0.05). Conclusion S. sputigena, Selenomonas sp. oral CS002 (OT 131) and Selenomonas sp. oral clone EW084 (OT 146) may be associated with the pathogenesis of GAgP, and their role in the onset and progression of this infection should be further investigated

    Daily portraits of five and six-year old boys: the play activity

    Get PDF
    Introduction: Daily life experiences provide maturity along human development, and the environments in which they occur are essential for this process. These experiences help to build children’s personalities and the way they deal with the world around them. Objectives: In this study, we aimed to understand the occupational behavior of four children aged five to six years old through their mothers’ reports. Methodology: The average time spent with daily activities is described, and playing was a central theme of analysis. We analyzed the preferences, companies and emotional characteristics of the play activity. We used an Activity Clock and semi-structured interviews with the children’s mothers as data collection instruments. Results: The main results show that most of their daily life time is spent with sleep, school and play activities. They indicate that children prefer games that challenge acquisitions that are under construction. Regarding company, these children still have their mothers as a reference to the play activity, but also peers their age or a little older. Conclusion: Play has an important representation in the daily occupational lives of these children and it stands as a key life experience to acquire skills and face challenges
    corecore