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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Síntese de biodiesel através de transesterificação enzimática de óleos vegetais catalisada por lipase imobilizada por ligação covalente multipontual

Rodrigues, Rafael Costa January 2009 (has links)
Biodiesel consiste de ésteres alquílicos de ácidos graxos produzidos pela transesterificação de triglicerídeos com álcoois de cadeia curta. Tradicionalmente, a reação ocorre na presença de catalisadores químicos, como álcalis ou ácidos. A utilização alternativa de lipases como biocatalisadores na reação de síntese do biodiesel não gera materiais residuais tóxicos, e o glicerol pode ser facilmente recuperado sem um processamento complexo. Neste trabalho estudou-se a síntese de biodiesel através da transesterificação enzimática de óleos vegetais e álcoois de cadeia curta catalisada pela lipase de Thermomyces lanuginosus (TLL). Primeiramente, as condições da reação de transesterificação, entre óleo de soja e etanol catalisada pela TLL em sua forma livre foram otimizadas através de planejamento experimental e da metodologia de superfície de resposta. A seguir, foram estudadas as condições para a reação catalisada pela TLL imobilizada comercial (Lipozyme TL-IM). Na etapa seguinte foram avaliados diferentes óleos vegetais (óleo de soja, óleo de girassol e óleo de arroz) e álcoois (metanol, etanol, propanol e butanol), na reação de transesterificação catalisada por três derivados enzimáticos comerciais de lipases de diferentes fontes (Lipozyme TL-IM, Novozym 435, Lipozyme RMIM), onde se verificou que cada lipase apresentou uma especificidade diferente em relação ao álcool preferente para a reação de transesterificação. Além disso, a reação utilizando diferentes óleos vegetais apresentou resultados semelhantes, mostrando ser este um fator mais dependente do ponto de vista econômico que processual. Também se estudou diferentes tratamentos para melhorar o reuso da lipase imobilizada, onde a lavagem do derivado com n-hexano, após cada ciclo, manteve a atividade da lipase em torno de 90% da atividade inicial após sete ciclos. Prosseguindo, foi estudada a imobilização e estabilização da TLL através da ligação covalente multipontual em suporte glioxil-agarose. Para obter isto se procedeu a aminação química da superfície da enzima, o que permitiu a obtenção de um derivado com alto grau de imobilização e alta estabilidade quanto à inativação por temperatura e solventes orgânicos. A seguir avaliou-se a possibilidade de reativação de derivados submetidos a processos de inativação. Em um primeiro momento os estudos foram realizados com derivados de TLL imobilizada unipontualmente em agarose ativada com brometo de cianogênio, onde foi possível obter a reativação completa do derivado inativado por solventes orgânicos através de incubação em meio aquoso. Verificou-se também que um dos principais pontos que dificultam a reativação de lipases é a recuperação do mecanismo de abertura do lid, que é facilitado com a presença de detergentes. Logo, estudos de reativação com derivados imobilizados por ligação covalente multipontual, mostraram que este tipo de imobilização auxilia no processo de reativação por oferecer mais pontos de referência no momento da reativação. A etapa final deste trabalho foi a aplicação do derivado de TLL imobilizado multipontualmente em suportes glioxil na reação de síntese de biodiesel. Verificou-se que este derivado foi mais ativo que o derivado comercial (Lipozyme TL-IM) na reação de transesterificação entre etanol e óleo de soja, obtendo 100% de conversão nas condições previamente otimizadas com presença de nhexano no meio de reação. Porém, quando se realizou a reação em dois passos, isto é a adição do etanol em duas etapas, foi possível obter 100% de conversão em 10 h de reação em um meio sem solvente. / Biodiesel consists of fatty acids alkyl esters, produced by transesterification of triglycerides with short-chain alcohols. Traditionally, the reaction occurs in the presence of chemical catalysts, such as acid or alkali. The alternative use of lipases as biocatalysts in the reaction of synthesis of biodiesel does not generate toxic waste material, and the glycerol can easily be recovered without complex processing. In this work it was studied the synthesis of biodiesel by transesterification of vegetable oils and short-chain alcohols catalyzed by lipase from Thermomyces lanuginosus (TLL). First, the conditions of transesterification reaction from soybean oil and ethanol catalyzed by TLL in its free form were optimized by experimental design and response surface methodology. Next, we studied the conditions for the reaction catalyzed by commercial immobilized TLL (Lipozyme TL-IM). In the next stage were evaluated some vegetable oils (soybean oil, sunflower oil and rice bran oil) and alcohols (methanol, ethanol, propanol and butanol) in the transesterification reaction catalyzed by three commercial enzyme preparations of lipases from different sources (Lipozyme TL-IM, Novozymes 435, Lipozyme RM-IM), where it was found that each lipase presented a different specificity in relation to preferred alcohol for the reaction of transesterification. In addition, the reaction using different vegetable oils presented similar results, showing that it is more dependent on the economic than technical aspects. It was also studied different treatments to improve the reuse of immobilized lipase, where washing the derivative with n-hexane after each batch, showed the high stability of the system, with activities of 90 % still remaining after seven cycles. Thus, it was studied the immobilization and stabilization of TLL through covalent multipoint immobilization in glyoxyl-agarose support. For this procedure, a chemical amination of the enzyme surface, allowed obtaining a derivative with a high degree of immobilization and high stability for inactivation by temperature and organic solvents. Then, it was evaluated the possibility of reactivation of derivatives previously inactivated. At first, the studies were carried out for TLL mild immobilized in cyanogen bromide activated agarose, where it was able to fully reactivate the derivative inactivated by organic solvents through incubation in aqueous medium. It was also noted that one of the main points that difficult the reactivation of lipases is the recovery of the mechanism for lid opening, which is helped by the presence of detergents. So, studies of reactivation with derivatives immobilized by multipoint covalent attachment showed that this type of immobilization helps the reactivation process by offering more reference points at the moment of reactivation. The final step of this study was the application of the TLL derivative multipointly immobilized on glyoxyl supports in the reaction of synthesis of biodiesel. It was found that this derivative was more active than the commercial derivative (Lipozyme TL-IM) in the transesterification reaction between ethanol and soybean oil, reaching 100% of yield conversion under the previously optimized conditions with the presence of n-hexane in the reaction medium. However, in the two stepwise ethanolysis it was possible to obtain 100% conversion in 10 h of reaction in a solvent-free system.
202

Manejo de esquivas emocionais na psicoterapia analítica funcional: Delineamento experimental de caso único / Management of emotional avoidance in Functional Analytic Psychotherapy: single-case experimental design

Milena Carvalho de Godoy Geremias 03 October 2014 (has links)
A partir do estudo e consolidação empírica da Psicoterapia Analítica Funcional (FAP) tem-se explorado cada vez mais a relação estabelecida entre terapeuta e cliente, no intuito de se compreender e aprimorar os processos de mudança clínica ocorridos em terapia. A literatura enfatiza que respostas emitidas por parte do terapeuta no decorrer do processo de autorrevelação do cliente podem impactar seu desfecho, facilitando ou dificultando exposições e verbalizações. Considerando que a FAP tem se ajustado bem a casos clínicos que apresentam dificuldades no estabelecimento de relações de intimidade, o objetivo central desta pesquisa foi investigar se o responder contingente do terapeuta às respostas de esquivas emocionais emitidas pelo cliente, aumenta a emissão de relatos sobre sentimentos, assim como o de autorrevelações em sessão e em seus relacionamentos extra consultório. Para isso, uma cliente com queixa de dificuldade em estabelecer relações interpessoais e uma terapeuta (com experiência clínica no manejo da FAP) foram selecionadas. O delineamento experimental de caso único apresentou o formato: A1-B1-A2-B2. As sessões foram filmadas e transcritas e os dados coletados foram analisados pela Escala de Classificação da Psicoterapia Analítica Funcional (FAPRS) adaptada. Doze sessões foram categorizadas e 4.094 (quatro mil e noventa e quatro) unidades de análises foram avaliadas. Os resultados indicaram que a variável independente (FAP) foi a responsável pela diminuição na emissão de comportamentos problema (CRBs1) e, principalmente, pelo aumento na emissão de comportamentos de melhora (CRBs2). Em outras palavras, durante a fase FAP, após a evocação da terapeuta, a cliente passou a entrar em contato com seus sentimentos e se autorrevelar mais efetivamente em terapia, de modo que seus comportamentos de esquiva emocional diminuíram. De maneira geral, as diferenças entre as fases FAP e não-FAP ficaram evidentes com os dados dos CRBs2 e não com os dos CRBs1. Os resultados corroboram a hipótese do estudo, fortalecem as evidências clínicas promovidas pela Psicoterapia Analítica Funcional e replicam os dados apresentados pelas pesquisas realizadas no Programa de Psicologia Clínica da USP com o uso da FAP e com delineamento experimental de caso único / Based on studies and empirical consolidation of Functional Analytic Psychotherapy (FAP), the relationship between therapist and client has been extensively explored in order to understand and enhance the process of clinical change that occurs during therapy sessions. The literature emphasizes that feedback provided by the therapist to the process of clients self-disclosure might affect and impact outcome by facilitating or hindering interpersonal exposure and verbalizations. Considering that FAP presents satisfactory results with clinical cases characterized by difficulties to establish intimate relationships, the aim of this research was to investigate whether the therapist contingent responding to clients emotional avoidance increases clients report of feelings, self-disclosure in therapy and in out-of-session relationships. For this study, a client with problems to establish interpersonal relationships and a therapist with clinical expertise on FAP were chosen. The single-case experimental design had the format: A1-B1-A2-B2. The sessions were recorded and transcribed and the data collected were coded using an adaptation of the Functional Analytic Psychotherapy Rating Scale (FAPRS). Twelve sessions were coded and 4.094 (four thousand and ninetyfour) units of analysis were analyzed. Results indicated that the independent variable (FAP) was responsible for decreasing the emission of problem behaviors (CRBs1) and above all for increasing the emission of improvements (CRBs2). In other words, during FAPs phase, after the therapist evoking, the client began to get in touch with her feelings and to self-disclose more effectively in therapy. As a result, her emotional avoidance behaviors decreased. In general, the differences between FAP and non-FAP phases were clearly showed in the data of the CBRs2 and not in the data of the CRBs1. The results corroborate the hypothesis of the study, strengthen clinical evidence of FAP and replicate the data presented in other research studies conducted in the Clinical Psychology Program at University of São Paulo using FAP and single-case designs
203

Tratamento fotocatalítico (TiO2/UV) de águas ácidas de lavagem de biodiesel / Photocatalytic treatment (TiO2/UV) of biodiesel washing acid waters

Alcyr da Cunha Barcelar Junior 15 June 2012 (has links)
As projeções mostram que o Brasil poderá consumir aproximadamente 50 bilhões de litros de biodiesel num futuro próximo. Frente a este cenário, surge a preocupação com tratamento de tamanha quantidade de efluente que pode ser gerado na produção do biodiesel. Os Processos Oxidativos Avançados (POAs) têm sido estudados como uma alternativa promissora para o tratamento de uma série de efluentes. O presente trabalho tem como objetivo tratar águas ácidas de lavagem geradas na produção de biodiesel com a fotocatálise heterogênea (TiO2/UV). Para tanto, elaborou-se um planejamento experimental, com a finalidade de se determinar os efeitos das variáveis independentes pH, temperatura e teor de TiO2. Em seguida, ajustou-se um modelo linear aos dados obtidos (R2 = 0,985). A condição ótima de tratamento foi: pH = 3,3; 20°C; e 0,1 g TiO2 L-1. Foram observadas a remoção de DQO, DBO e COD, a redução do espectro de absorção no ultravioleta, a biodegradabilidade e ecotoxicidade. Tanto o processo fotocatalítico quanto a fotólise foram eficazes na degradação dos compostos presentes no efluente. Alcançou-se aproximadamente 80, 78 e 61% de remoção de DQO, DBO e COD, respectivamente, após 240 min de irradiação. O efluente fotocatalisado apresentou uma melhora marginal na biodegradabilidade. A fotólise não é indicada para o tratamento desse efluente por ter gerado ecotoxicidade a sementes de Lactuca sativa. / Projections show that Brazil may consume approximately 50 billion liters of biodiesel in the near future. In face of this scenario, the treatment of the huge amount of wastewaters that can be generated in the production of biodiesel is a worry. Advanced Oxidation Processes (AOPs) have been studied as a promising alternative for treating several wastewaters. The present work is aimed at treating biodiesel washing acid waters with heterogeneous photocatalysis (TiO2/UV). For that purpose, an experimental design was performed to assess the effects of the independent variables pH, temperature, and TiO2 content. Next, a linear model was fit to the obtained data (R2 = 0,985). The optimum treatment condition was: pH = 3,3; 20°C, and 0.1 g TiO2 L-1. The removal of COD, BOD, and DOC, the reduction of the ultraviolet absorption spectrum, biodegradability and ecotoxicity. Both photocatalysis and photolysis were effective in degrading the compounds present in the wastewater. Removals of approximately 80, 78, and 61% of COD, BOD, and DOC, respectively, were achieved after 240 min of irradiation. The photocatalyzed wastewater showed a marginal improvement in biodegradability. Photolysis is not indicated for treating this wastewater as ecotoxicity towards seeds of Lactuca sativa was generated.
204

Purifica??o de glicerol utilizando diferentes adsorventes: An?lise t?cnica e termodin?mica / Glycerol purification using different adsorbents: Technical and thermodynamic analysis

ALVES, Amanda de Paula 23 February 2017 (has links)
Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-09-12T19:05:23Z No. of bitstreams: 1 2017 - Amanda de Paula Alves.pdf: 2949048 bytes, checksum: 68f405efb8be6119401dfd85e1d5768a (MD5) / Made available in DSpace on 2017-09-12T19:05:23Z (GMT). No. of bitstreams: 1 2017 - Amanda de Paula Alves.pdf: 2949048 bytes, checksum: 68f405efb8be6119401dfd85e1d5768a (MD5) Previous issue date: 2017-02-23 / The large amount of glycerol, produced in the last decades, generated as a by product of biodiesel production is object of inumerous studies searching for different technologies for its purification. Crude glycerol obtained as a by-product in the transesterification process is composed of alcohol, water, inorganic salts, free fatty acids, mono-, di-, triglycerides, among other organic materials and wastes in different concentrations. It is of extreme importance the purification of glycerol in order to reduce environmental problems due to its accumulation. There are current effective technologies in purifying and refining crude glycerol. However, they are considered unfeasible for small and medium production units due to the high cost and high energy demand. In this way, it is essential that new purification routes of low cost and high efficiency, as well as new markets, be developed. The adsorption process is promising and very favorable technique to remove the contaminants from glycerin due to its low cost, simplicity of design and operation. In this point of view, the objective of this work was to select an adsorbent for the purification of crude glycerol obtained from the transesterification reaction of residual oil. The evaluation of the efficiency and the best operacional conditions were studied using three types of adsorbents: Pure-Flo Supreme B81 clarifying clay, activated charcoal and diatomaceous earth. Preliminary adsorption experiments were carried out using a synthetic solution of glycerin and soybean oil, in order to verify the influence of glycerin concentration in the solution, as well as the behavior of the glycerol contaminants in the adsorption process. In order to reach the objective, the influence and optimization of the process variables as temperature (298.15, 305.65 and 313.15 K), amount of adsorbent (1.2, 1.8 and 2.4 g) and glycerol concentration (30, 50 and 70% v/v) were evaluated through an experimental design. The most significant variable was glycerol concentration, and results indicated high glycerol content after purification: 97.25% for diatomaceous earth, 95.59% for activated carbon and 90.26% for clay. Through the optimization of these variables, experiments were carried out to study the thermodynamics and kinetics of the reaction. The equilibrium time was less than 60 minutes for the three adsorbents. The negative values of Gibbs free energy (?G) showed that the adsorption of the contaminants is a spontaneous process. The negative values for enthalpy change (?H) and positive entropy (?S) values for clay and activated carbon indicate an exothermic nature and that the contaminant molecules are more randomnless in the adsorbed state than in solution. The positive value of ?H for diatomaceus earth indicates that the adsorption process for this adsorbent is endothermic. The adsorption results obtained at 298.15, 305.65 and 313.15 K showed that the experimental data were well correlated with the Langmuir, Freundlich and Redlich-Peterson isotherms models. The purification of crude glycerol using the same adsorbents did not show an effective result. The results showed that the adsorbents were not able to adsorb the impurities, but rather a small amount of glycerol. The adsorption carried out for purification did not clarify the glycerin, concluding that only the adsorption process is not suitable for purification of the crude glycerol, and a pre-purification step is necessary for the previous removal of the contaminants. / O excedente de glicerol produzido nas ?ltimas d?cadas, gerado como subproduto da produ??o de biodiesel, est? associado a constantes pesquisas por fontes alternativas de energia e vem criando uma demanda na busca de diferentes tecnologias para sua purifica??o. A glicerina bruta obtida como subproduto no processo de transesterifica??o ? composta por ?lcool, ?gua, sais inorg?nicos, ?cidos graxos livres, mono-, di-, triglicer?deos, entre outras mat?rias org?nicas e res?duos em diferentes quantidades. ? de extrema import?ncia a purifica??o do glicerol, a fim de reduzir problemas ambientais devido ao seu ac?mulo. Existem tecnologias atuais eficazes na purifica??o e refino do glicerol bruto. Por?m, s?o consideradas invi?veis para pequenas e m?dias produ??es, devido ?s restri??es de custos e alta demanda energ?tica. Dessa forma, ? indispens?vel que novas rotas de purifica??o de menor custo e maior efici?ncia, assim como novos mercados, sejam desenvolvidos. A adsor??o desponta como uma t?cnica promissora e muito favor?vel para a remo??o dos contaminantes da glicerina, devido ao seu baixo custo, simplicidade de projeto e opera??o. Diante do exposto, o objetivo deste trabalho foi selecionar um adsorvente para a purifica??o do glicerol bruto obtido da rea??o de transesterifica??o de ?leo residual. Para a avalia??o da efici?ncia e escolha das melhores condi??es de purifica??o, foram avaliados tr?s tipos de adsorventes: argila clarificante Pure-Flo Supreme B81, carv?o ativado e terra diatom?cea. Experimentos de adsor??o foram realizados utilizando uma solu??o sint?tica de glicerina P.A. e ?leo de soja, com o intuito de verificar a influ?ncia da concentra??o da glicerina na solu??o, assim como o comportamento dos contaminantes do glicerol no processo de adsor??o. Para atingir o objetivo, avaliou-se a influ?ncia e otimiza??o das vari?veis de processo como temperatura (298,15, 305,65 e 313,15 K), quantidade de adsorvente (1,2, 1,8 e 2,4 g) e concentra??o de glicerol (30, 50 e 70% v/v) atrav?s de um planejamento experimental. A vari?vel mais significativa foi a concentra??o de glicerol, e resultados indicaram alto teor de glicerol ap?s a purifica??o: 97,25% para terra diatom?cea, 95,59% para carv?o e 90,26% para argila. Al?m disso, foram realizados experimentos para o estudo da termodin?mica e cin?tica da rea??o e o tempo necess?rio para o sistema alcan?ar o equil?brio foi inferior a 60 minutos para os tr?s adsorventes. Os valores negativos da varia??o da energia livre de Gibbs (?G) mostraram que a adsor??o dos contaminantes ? um processo espont?neo. Os valores negativos para varia??o de entalpia (?H) e os valores positivos de entropia (?S) para argila e carv?o ativado, indicam uma natureza exot?rmica e que as mol?culas dos contaminantes encontram-se mais desordenadas no estado adsorvido do que em solu??o. O valor positivo de ?H para a terra diatom?cea indica que o processo de adsor??o para esse adsorvente ? endot?rmico. As an?lises dos resultados de adsor??o obtidos nas temperaturas de 298,15, 305,65 e 313,15 K, mostraram que os dados experimentais foram bem correlacionados ?s isotermas de Langmuir, Freundlich e Redlich Peterson. Utilizando as mesmas vari?veis para o processo de adsor??o usando o glicerol bruto, os resultados mostraram que os adsorventes n?o foram capazes de adsorver as impurezas, mas sim glicerol. A adsor??o realizada para purifica??o n?o clarificou a glicerina, indicando que n?o houve remo??o das impurezas, concluindo que somente o processo de adsor??o n?o ? apropriado para purifica??o do glicerol bruto, sendo necess?rio uma pr?-purifica??o para pr?via remo??o de alguns contaminantes.
205

Doseamento microbiológico de gentamicina por difusão em agar - proposta de delineamento experimental / Microbiological assay of gentamicin sulfate by agar diffusion - proposal of experimental design

Lourenço, Felipe Rebello 18 December 2006 (has links)
A gentamicina é um complexo antibiótico de largo espectro, produzido por actinomicetos do gênero Micromonospora e classificado entre os antibióticos aminoglicosídeos, utilizado no tratamento de infecções graves, devidas a microrganismos Gram-negativos. Alterações da sua atividade antimicrobiana, não demonstradas pelos ensaios químicos, podem ser avaliadas pelos ensaios microbiológicos. O objetivo deste trabalho foi comparar os delineamentos experimentais 5 x 1, 2 x 2 e 3 x 1, avaliando-se os parâmetros de validação de especificidade, linearidade, faixa ou intervalo, precisão e exatidão para cada delineamento experimental em diferentes níveis de concentração, apresentações e lotes. O plano de trabalho constituiu-se na realização de 81 ensaios (em 3 réplicas) de doseamento microbiológico de gentamicina. As concentrações das soluções empregadas foram preparadas numa faixa de 1,0 µg/mL a 5,0 µg/mL, diluídos em tampão fosfato 0,1 M pH 8,0. O meio utilizado foi o meio antibiótico no. 11, com Staphyloccocus epidermidis (ATCC 12228). Empregou-se 21 mL de meio como camada base e 4 mL de meio inoculado à 1% como camada superfície. As placas foram incubadas por 16-18 horas à 37 ± 1 °C. Os três delineamentos empregados apresentaram especificidade adequada para análise de creme dermatológico e solução injetável contendo sulfato de gentamicina. Também apresentaram exatidão e linearidade no intervalo avaliado. Os delineamentos não apresentaram diferença significativa quanto a precisão. Os resultados foram comparados através da determinação de índices de capacidade do sistema de medição. A análise estatística demonstrou que não há diferença significativa entre os resultados obtidos pelos delineamentos 5 x 1, 2 x 2 e 3 x 1, sendo equivalentes e intercambiáveis. / Gentamicin is a broad-spectrum antibiotic complex produced by actinomycetes belonging to Micromonospora genus and classified among aminoglycoside antibiotics, used in the treatment of serious infections derived from Gram-negative microorganisms. Alterations of their antimicrobial activity not shown in chemical assays can be evaluated through microbiological assays. The aim of this work was to compare 5 x 1, 2 x 2 and 3 x 1 experimental designs, evaluating validation parameters of specificity, linearity, range, precision, and accuracy for each experimental design in different levels of concentration, presentation, and lots. It consisted of 81 assays (in 3 replicas) of gentamicin microbiological dosage. The concentrations of the solutions used were employed in a range from 1.0 µg/ml to 5.0 µg/ml, diluted in phosphate buffer 0.1 M pH 8.0. Antibiotic medium number 11 was used, with Staphyloccocus epidermis (ATCC 12228)21ml of medium were used as base layer and 4 ml of medium inoculated at 1% were used as surface layer. The plates were incubated for 16-18 hours at 37 ± 1 ºC. The three designs employed showed adequate specificity for analysis of dermatological cream and injectable solution containing gentamicin sulphate. They also showed accuracy and linearity in the range evaluated, but not a significant difference concerning precision. The results were compared by means of the determination of the rates of measurement system capacity. The statistical analysis demonstrated that there is no significant difference among the results obtained.
206

How a Systematic Approach to Uncertainty Quantification Renders Molecular Simulation a Quantitative Tool in Predicting the Critical Constants for Large <em>n</em>-Alkanes

Messerly, Richard Alma 01 December 2016 (has links)
Accurate thermophysical property data are crucial for designing efficient chemical processes. For this reason, the Design Institute for Physical Properties (DIPPR 801) provides evaluated experimental data and prediction of various thermophysical properties. The critical temperature (Tc), critical density (ρc), critical pressure (Pc), critical compressibility factor (Zc), and normal boiling point (Tb) are important constants to check for thermodynamic consistency and to estimate other properties. The n-alkane family is of primary interest because it is generally assumed that other families of compounds behave similarly to the n-alkane family with increasing chain-length. Unfortunately, due to thermal decomposition, experimental measurements of Tc, ρc, and Pc for large n-alkanes are scarce and potentially unreliable. For this reason, molecular simulation is an attractive alternative for estimating the critical constants. However, molecular simulation has often been viewed as a tool that is limited to providing qualitative insight. One key reason for this perceived weakness is the difficulty in quantifying the uncertainty of the simulation results. This research focuses on a systematic top-down approach to quantifying the uncertainty in Gibbs Ensemble Monte Carlo (GEMC) simulations for large n-alkanes. We implemented four different methods in order to obtain quantitatively reliable molecular simulation results. First, we followed a rigorous statistical analysis to assign the uncertainty of the critical constants when obtained from GEMC. Second, we developed an improved method for predicting Pc with the standard force field models in the literature. Third, we implemented an experimental design to reduce the uncertainty associated with Tc, ρc, Pc, and Zc. Finally, we quantified the uncertainty associated with the Lennard-Jones 12-6 potential parameters. This research demonstrates how uncertainty quantification renders molecular simulation a quantitative tool for thermophysical property evaluation. Specifically, by quantifying and reducing the uncertainty associated with molecular simulation results, we were able to discern between different experimental data sets and prediction models for the critical constants. In this regard, our results enabled the development of improved prediction models for Tc, ρc, Pc, and Zc for large n-alkanes. In addition, we developed a new Tb prediction model in order to ensure thermodynamic consistency between Tc, Pc, and Tb.
207

Estudo do processo de cultivo da microalga chlorella minutíssima e caracterização termoquímica de sua biomassa para aplicação em gaseificação /

Laiate, Juliana. January 2018 (has links)
Orientador: Messias Borges Silva / Coorientador: Ronney Arismel Mancebo Boloy / Banca: José Roberto Dale Luche / Banca: José Miguel Angulo Ibáñez / Banca: Patricia Caroline Molgero de Rós / Banca: Daniela Helena Pelegrine Guimarães / Resumo: O interesse na diversificação da matriz energética por meio de fontes de energias renováveis tem promovido mudanças no âmbito nacional e internacional, em setores acadêmicos, industriais, sociais e governamentais com foco no desenvolvimento de processos biotecnológicos baseados nos três pilares da sustentabilidade: ambiental, social e econômico. Frente a esse contexto, as microalgas são consideradas uma fonte promissora alternativa para a produção de biocombustíveis por apresentarem alta taxa de crescimento e de concentração de lipídeos. O presente trabalho realizou um estudo do processo de cultivo da microalga marinha Chlorella minutíssima por meio da ferramenta DOE - Design of Experiments para maximização da sua concentração microalgal e do teor lipídico simultaneamente, além de sua caracterização termoquímica para aplicação no processo de gaseificação. O cultivo ocorreu em fotobiorreator tubular descontínuo do tipo coluna de bolhas seguindo o arranjo ortogonal L8 de Taguchi, e as variáveis de processo foram fluxo de CO2 na alimentação, concentração de nitrato, concentração de fosfato, suplementação, temperatura e salinidade. A investigação demonstrou que a concentração de nitrato e fosfato, o fluxo de gás carbônico, a suplementação do meio e a temperatura são fatores influentes na concentração microalgal e no teor lipídico, sendo a melhor configuração para maximização conjunta, utilizando-se a função desirability, com o nitrato operando em nível alto e os demais fatores em... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The interest in diversifying the energy matrix through renewable energy sources has promoted changes at the national and international levels in academic, industrial, social and governmental sectors, focused on the development of biotechnological processes based on the three pillars of sustainability: environmental, social and economic. In this context, microalgae are considered a strong promising alternative source for the production of biofuels due to their high rate of growth and lipid concentration. The present work carried out a study of the cultivation process of the marine microalgae Chlorella minutíssima using DOE - Design of Experiments to maximize the cell growth and the lipid content simultaneously, besides its thermochemical characterization for application in the gasification process. Cultivation occurred in a discontinuous-tubular photobioreactor, bubble-column type, following Taguchi L8 Orthogonal Array design, and the process variables were: CO2 feed flow rate, nitrate concentration, phosphate concentration, supplementation (metals and vitamins), temperature and salinity. Results showed that the nitrate and phosphate concentration, CO2 feed flow, supplements and temperature are influential factors in the cell growth and lipid content, and the best configuration presenting good results for simultaneous maximization, using desirability, was nitrate operating at high level and the other factors at low level. Ultimate analysis provided levels consistent with some ... (Complete abstract click electronic access below) / Doutor
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INFORMAL ART THERAPY GROUP AMONG MINORITY SENIORS IN INDEPENDENT LIVING COMMUNITIES

Rodriguez, Jennifer 01 June 2018 (has links)
The elderly population have developed some resistance toward accepting community-based social services. Such resistance could be detrimental to the well-being of low-income seniors by hindering their chance of accessing services intended for them in the first place. Art therapy is seen as a promising intervention against client resistance. This study evaluated the effectiveness of art therapy on reducing resistance to services among low-income seniors living in independent living communities. Through a pre-experimental design, this study analyzed administrative data for a sample of 37 participants from a social service agency in Southern California. Results from two non-parametric tests (WilcoxonSigned-Rank and Mann-Whitney-U) revealed that art therapy is very effective in reducing resistance among seniors. Implications for gerontology and social services providers were discussed.
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The Effects of Online Homework on Achievement and Self-efficacy of College Algebra Students

Brewer, David Shane 01 May 2009 (has links)
This study compared the effectiveness, in terms of mathematical achievement and mathematics self-efficacy, of online homework to textbook homework over an entire semester for 145 students enrolled in multiple sections of college algebra at a large community college. A quasi-experimental, posttest design was used to analyze the effect on mathematical achievement, as measured by a final exam. A pretest-posttest design was used to analyze the effect on mathematics self-efficacy, as measured by the Mathematics Self-efficacy Scale. The control group completed their homework using the textbook and the treatment group completed similar homework using an online homework system developed by the textbook publisher. All class sections followed a common syllabus, schedule, and homework list and completed a common, departmental final exam. Classroom observations were also used as a way to establish the similarity between groups. The results of the study found that while the treatment group generally scored higher on the final exam, no significant difference existed between the mathematical achievement of the control and treatment groups. Both the control and treatment group did experience significant improvements in their mathematics self-efficacy, but neither group demonstrated more improvement than the other. When students were divided based on incoming math skill level, analysis showed that low-skilled students who used online homework exhibited significantly higher mathematical achievement than low-skilled students who used textbook homework. Exploratory analysis also showed that more students with low incoming skill levels and more repeating students received a passing grade when using online homework than did their higher-skilled, first-time counterparts, although the differences were not significant. Based on this study it appears as if online homework is just as effective as textbook homework in helping students learn college algebra and in improving students' mathematics self-efficacy. Online homework may be even more effective for helping the large population of college algebra students who enroll in the course with inadequate prerequisite math skills. Instructors and researchers should consider the possibility that online homework can successfully help certain populations of students develop understanding better than traditional approaches. This study has implications for mathematics instructors and for online homework system developers.
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Data Analysis Using Experimental Design Model Factorial Analysis of Variance/Covariance (DMAOVC.BAS)

Newton, Wesley E. 01 May 1985 (has links)
DMAOVC.BAS is a computer program written in the compiler version of microsoft basic which performs factorial analysis of variance/covariance with expected mean squares. The program accommodates factorial and other hierarchical experimental designs with balanced sets of data. The program is writ ten for use on most modest sized microprocessors, in which the compiler is available. The program is parameter file driven where the parameter file consists of the response variable structure, the experimental design model expressed in a similar structure as seen in most textbooks, information concerning the factors (i.e. fixed or random, and the number of levels), and necessary information to perform covariance analysis. The results of the analysis are written to separate files in a format that can be used for reporting purposes and further computations if needed.

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