874 resultados para Acidic medium
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The asymmetric reduction of 2-chloro-1-phenylethanone (1) by seven strains of marine fungi was evaluated and afforded (S)-(-)-2-chloro-1-phenylethanol with, in the best case, an enantiomeric excess of 50% and an isolated yield of 60%. The ability of marine fungi to catalyse the reduction was directly dependent on growth in artificial sea water-based medium containing a high concentration of Cl(-) (1.2 M). When fungi were grown in the absence of artificial sea water, no reduction of 1 by whole cells was observed. The biocatalytic reduction of 1 was more efficient at neutral rather than acidic pH values and in the absence of glucose as co-substrate.
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The extracellular hemoglobin from Glossoscolex paulistus (HbGp) has a molecular mass of 3.6 M Da, It has a high oligomeric stability at pH 7.0 and low autoxidation rates, as compared to vertebrate hemoglobins. In this work, fluorescence and light scattering experiments were performed with the three oxidation forms of HbGp exposed to acidic pH. Our focus is on the HbGp stability at acidic pH and also on the determination of the isoelectric point (pI) of the protein. Our results show that the protein in the cyanomet form is more stable than in the other two forms, in the whole range. Our zeta-potential data are consistent with light scattering results. Average values apt obtained by different techniques were 5.6 +/- 0.5, 5.4 +/- 0.2 and 5.2 +/- 0.5 for the oxy, met, and cyanomet forms. Dynamic light scattering (DLS) experiments have shown that, at pH 6.0, the aggregation (oligomeric) state of oxy-, met- and cyanomet-HbGp remains the same as that at 7.0. The interaction between the oxy-HbGp and ionic surfactants at pH 5.0 and 6.0 was also monitored in the present study. At pH 5,0, below the protein pI, the effects of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium chloride (CTAC) are inverted when compared to pH 7.0. For CTAC, in acid pH 5.0, no precipitation is observed, while for SDS an intense light scattering appears due to a precipitation process. HbGp interacts strongly with the cationic surfactant at pH 7.0 and with the anionic one at pH 5.0. This effect is due to the predominance, in the protein surface, of residues presenting opposite charges to the surfactant headgroups. This information can be relevant for the development of extracellular hemoglobin-based artificial blood substitutes.
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This thesis presents English-medium instruction (EMI) in the Swedish context, focusing on perspectives and practices in two schools. The research question is as follows: How and why is EMI offered, chosen, and practiced in the Swedish upper secondary school today? The aim is to explore the status of the educational option, the reasons for offering EMI to stakeholders, the stakeholders’ beliefs about and goals of EMI, and the implementation of EMI in the classroom. A survey of all upper secondary schools in Sweden was conducted to ascertain the spread of content teaching through a foreign language. The educational context was studied from an ecological perspective using methods based in linguistic ethnography. Language alternation, academic language, and language hierarchy were all considered. Interviews were analysed for content; and classroom language use was analysed for language choice and function. The concepts of affordance and scaffolding together with translanguaging were key. The de facto policies of the micro contexts of the schools were examined in light of the declared national policy of the macro context of Sweden. The results indicate that the option in Swedish schools has not increased, and also tends to only be EMI—not Content and Language Integrated Learning (CLIL) or instruction through other languages. EMI is offered for prestige, an international profile, marketing potential and personal interest. EMI students are academically motivated and confident, and see the option as “fun”. 100% EMI in the lessons is not the goal or the practice. Translanguaging is abundant, but how language alternation is perceived as an affordance or not differs in the two schools. One focuses on how the languages are used while the other focuses on how much each language is used. In conclusion, the analysis suggests that a development of definitions and practices of EMI in Sweden is needed, especially in relation to language policy and language hierarchy.
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A finalidade deste trabalho ´e apresentar uma revis˜ao da teoria do transporte de part´ıculas em meios compostos por uma mistura aleat´oria bin´aria. Para atingir este objetivo n´os apresentamos brevemente alguns conceitos b´asicos de teoria do transporte, e ent˜ao discutimos em detalhes a deriva¸c˜ao de duas abordagens desenvolvidas para a solu¸c˜ao de tais problemas: os modelos de mistura atˆomica e de Levermore-Pomraning. Providenciamos ainda, com o uso da formula¸c˜ao LTSN, compara ¸c˜oes num´ericas destes modelos com resultados de benchmark gerados atrav´es de um processo de Monte Carlo.
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Neste trabalho, o mercado brasileiro de crédito para pequenas e médias empresas (PMEs) é analisado sob a perspectiva do marketing adaptativo, em que se assume que atividades mercadológicas como segmentação, gestão de relacionamento com clientes, apreçamento e desenvolvimento de produtos, são determinadas pela utilidade obtida por agentes de mercado ao atenderem a demanda. Identifica-se que a existência de assimetria de informações e de custos de transação limita e direciona as atividades de marketing no mercado estudado. A partir de uma amostra com 65.535 propostas de crédito, recebidas e avaliadas por um grande banco brasileiro entre janeiro de 2004 e setembro de 2006, estima-se a utilidade do banco em operações de crédito. Adicionalmente, 17.149 transações de empréstimos concedidos pelo banco ao segmento de pequenas empresas entre abril de 2006 e março de 2007, são investigadas. Finalmente, um conjunto de dados com 1,636 registros obtidos pela junção das bases de dados de propostas e de transações mencionados, é analisado em termos das relações entre taxas de juros e os totais de cobertura oferecidas por meio de garantias de crédito. Os resultados revelam a existência de um ambiente de marketing adaptativo, em que os pequenos tomadores de crédito produtivo são racionados, e aceitam pagar taxas de juros mais elevadas do que outros segmentos. Produtos de créditos baseados em garantias líquidas e com altas taxas de juros são desenvolvidos para suprir de maneira oportuna este segmento racionado de pequenas empresas. Ademais, a utilidade do banco em operações de crédito é afetada pela informação privada que captura ao longo de relacionamentos mantidos com seus cientes. Os resultados implicam que o sistema de marketing financeiro brasileiro não desempenha papel formativo no desenvolvimento econômico, que seria de fomento ao crédito produtivo por meio de empréstimos a baixo custo para pequenas e médias empresas. Um sistema formativo de marketing é improvável em um ambiente com informação imperfeita, como o mercado de crédito brasileiro. O estudo traz informações úteis àqueles interessados no desenvolvimento de mercados de crédito produtivo, tais como profissionais de instituições financeiras; agentes responsáveis por políticas públicas e monetárias de fomento ao crédito; e empreendedores de pequeno e médio porte que necessitem de financiamento externo para seus negócios.
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Cultura organizacional e gestão de recursos humanos (GRH) são componentes fundamentais para a estratégia corporativa raramente estudada no contexto das pequenas e médias empresas (PME) no setor de serviços profissionais, um ambiente no qual o capital humano das empresas companhias é particularmente importante. Um estudo de caso de uma empresa de gestão de investimentos inglesa foi realizado. A PME quase triplicou o seu quadro de funcionários, de menos de 50 a mais de 140, nos últimos seis anos. Cultura e GRH foram pesquisadas tanto historicamente quanto no momento atual por meio de uma combinação de entrevistas individuais, observação direta durante as visitas ao local e análise documental. Foi verificado que a G RH (junto com um número de outras estruturas e processos internos) tornou-se mais formal, apesar do fato de que a empresa começou com políticas de RH relativamente desenvolvidas, em comparação com outras pequenas empresas. Uma possível explicação para esta estruturação das práticas de RH é que empresas do setor de serviços profissionais tendem a dar uma importância especial à qualidade da sua força de trabalho. Esta relativa estabilidade cultural pode ser explicada pelo fato da cultura ser forte e é mantida tanto inconscientemente quanto conscientemente, por meio de mecanismos como o planejamento de pessoal, recrutamento e remuneração. As conclusões, por conseguinte, demonstram que as atitudes e percepções nem sempre mudam tão rápido quanto sistemas organizacionais, e que a relação entre cultura e gestão de recursos humanos pode ser complexa; a formalização da GRH pode reforçar a mudança cultural em certos aspectos, ao mesmo tempo abrandá-lo em outros.
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This thesis aims to open a theoretical discussion on the importance of cluster for the development of Small and Medium Enterprises. The methodology applied was based on bibliographical and qualitative research. The basic questions raised by this study can be summarized as follows: How the creation of a cluster will help in the development of the SME?. Consequently, the final objective of the work is to identify which are the characteristics that help into the success of a Small & Medium Enterprises inserted in a cluster. The answer to this question led the research to a better understanding of (i) the characterization of the Small & Medium Enterprises; (ii) the clusters theory; (iii) evidence for a developed (Italy) and a developing (Chile) country that support our proposition to verify. The main results confirm the relevance of the cluster for the development of the Small and Medium Enterprises because of the collective efficiency that generates, improving the funding conditions, the exporter capacity and diminishing the activities costs of the small companies that are part of the conglomerate.
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Known for thousands of years, tuberculosis (TB) is the leading cause of mortality by a single infectious disease due to lack of patient adherence to available treatment regimens, the rising of multidrug resistant strains of TB (MDR-TB) and co-infection with HIV virus. Isoniazid and rifampicin are the most powerful bactericidal agents against M. tuberculosis. Because of that, this couple of drugs becomes unanimity in anti-TB treatment around the world. However, the rifampicin in acidic conditions in the stomach can be degraded rapidly, especially in the presence of isoniazid, which reduces the amount of available drug for absorption, as well as its bioavailability, contributing to the growing resistance to tuberculostatic drugs. Rifampicin is well absorbed in the stomach because of its high solubility between pH 1 and 2 and the gastric absorption of isoniazid is considered poor, therefore it is mostly intestinal. This work has as objective the development of gastro-resistant multiple-systems (granules and pellets) of isoniazid aiming to prevent the contact with rifampicin, with consequent degradation in acid stomach and modulate the release of isoniazid in the intestine. Granules of isoniazid were obtained by wet method using both alcoholic and aqueous solutions of PVP K-30 as aggregating and binder agent, at proportions of 5, 8 and 10%. The influence of the excipients (starch, cellulose or filler default) on the physical and technological properties of the granules was investigated. The pellets were produced by extrusionesferonization technique using isoniazid and microcrystalline cellulose MC 101 (at the proportion of 85:15) and aqueous solution of 1% Methocel as platelet. The pellets presented advantages over granular, such as: higher apparent density, smaller difference between apparent and compaction densities, smoother surface and, especially, smaller friability, and then were coated with an organic solution of Acrycoat L 100 ® in a fluidized bed. Different percentages of coating (15, 25 and 50%) were applied to the pellets which had their behavior evaluated in vitro by dissolution in acidic and basic medium. Rifampicin dissolution in the presence of uncoated and coated isoniazid pellets was evaluated too. The results indicate that the gastro resistance was only achieved with the greatest amount of coating and isoniazid is released successfully in basic step. The amount of rifampicin in the dissolution medium when the isoniazid pellets were not coated was lower than in the presence of enteric release pellets. Therefore, the polymer Acrycoat L 100 ® was efficient for coating with gastro-resistant function and can solve the problem of low bioavailability of rifampicin and help to reduce its dosage
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Xanthan is a important biopolymer for commercial purpose and it is produced in two stages by Xanthomonas campestris. In the first one, the bacterium is cultivated in the complex medium enriched in nitrogen and the biomass produced is used as inoculum for the next stage in which the gum is produced in another medium. In this work a new medium for the first stage is proposed in place of currently used YM medium. Different formulated growth media were studied and the correspondent biomass produced was analysed as inoculum for the second stage. The inoculum and gum were produced by batch process in shaker at 27A degrees C in pH 6.0 and at 30A degrees C in pH 7.0, respectively. The gum was precipitated with ethanol (3:1 v/v). The dryed biomass and xathan gum produced were determined by drying in oven at 105 and 40A degrees C, respectively. The viscosity of the fermentation broth and 1% gum solution in water were determined in Brookfield viscometer. The formulated medium presented the increase in gum production (30%), broth (136%) and 1% gum solution viscosity (60%) compared to YM, besides the inferior cost. The results showed the importance of the quality of the inoculum from the first stage of the culture which influenced on the gum viscosity in the second stage.