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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.
51

Development of electrocatalysts for glycerol oxidation

Padayachee, Diandree January 2013 (has links)
Glycerol is a very promising alternative fuel to hydrogen in fuel cells. However, the utilisation of glycerol as a fuel requires a good catalyst, due to the slow kinetics of glycerol electrooxidation. Gold has been identified as a promising catalyst due to its high activity and stability for glycerol electrooxidation – although the overpotentials are higher than on platinum and palladium. Modification of a nano-Au/C catalyst by the addition of MnO2, in an attempt to further improve the activity and lower the overpotential for glycerol oxidation, was therefore first explored. This was followed by investigations into the effects of gold particle size and loading. Finally, the effect of gold particle size on oxidation of gold-catalysed glycerol oxidation intermediates was also briefly explored. Studies into MnO2 addition showed that the pre-deposition of MnO2 yielded catalysts with smaller, more uniform gold particles, and catalysts with MnO2 contents of 5 and 9 wt % had higher mass activities and lower onset- and peak- potentials than Au/C. All the Au/xMnO2/C catalysts were more active than the palladium- and platinum-based catalysts reported in literature, which effectively demonstrated the advantage of using a gold-based catalyst for glycerol oxidation – especially when supported by MnO2 which lowered the overpotential for glycerol oxidation over gold. For the study into gold particle size, small gold particles of average diameter ≤ 4.7 nm had higher gold mass-based activities than medium-sized (14.7 nm) particles and were at least twice as active as catalysts containing large (≥ 43 nm) gold particles. The small gold particles also gave lower glycerol oxidation onset potentials, which was attributed to the predominance of Au(110) planes on those particles. Glycerol oxidation also appeared to proceed further along the oxidation pathway over small gold particles, which was confirmed in preliminary studies into the oxidation of glycerol oxidation intermediates. However, specific activity increased with increasing gold particle size, due mainly to the higher intrinsic activity of the Au(111) plane, which increased relative to Au(110) with increasing gold particle size. The important requirements for fuel cell applications are factors such as high mass activity, low overpotentials and high stability – all of which were met by the catalysts containing small gold particles defined by predominantly Au(110) facets. Investigations into the gold loading effect showed similar mass- and specific- activities for catalysts with 5-20 % gold loading. However, only the catalysts with higher gold loadings (15-20 %) did not deactivate early during CV, indicating that a larger gold surface area is necessary to resist poisoning at high potentials. On the basis of low onset potentials, high mass activity, and stability at low overpotentials, a minimum gold loading of 12.5 % appears to be necessary for a supported gold catalyst with small gold nanoparticles; although even higher loadings may be preferable for a higher power output in a fuel cell. Importantly, the insights gleaned from this study on the fundamental properties required for early activation, activity and stability of the gold catalysts could lead to a more intelligent design of gold-based catalysts in future.
52

Onsager Heat of Transport at the Liquid-Vapour Interface of Glycerol-Water Solutions

James, Ronald Arthur January 2007 (has links)
The Onsager heat of transport, Q*, has been measured for water vapour above glycerol-water solutions (75 % to 94.5 % glycerol) over a temperature range of -46 to -32 ℃. For solutions of concentrations 80 % and above, Q* varied from 5.41 kJ mol-1 ± 0.97 to 17.37 kJ mol-1 ± 2.61, consistent with previous results for aniline and n-heptanol. The dissociation of glycerol-water complexes was not rate determining, as was the case for sulfuric acid-water solutions, and therefore the glycerol-water system is a better two component system analog for comparison with the CO2-water system than the sulfuric acid-water system.
53

Functional analysis of some yeast genes

El-Hassi, Mohamed F. January 1997 (has links)
A series of mutant strains of the yeast Saccharomyces cerevisiae that are sensitive to osmotic stress and also have a defect in vacuolar biogenesis have been isolated (M. Latterich, PhD Thesis 1992). The mutations that cause this pleiotropic phenotype are termed ssv, for salt sensitive vacuolar mutants. Complementation analysis has revealed that ssv mutations fall into one of 18 complementation groups. A MAP kinase related signal transduction pathway, termed the HOG pathway for High Osmolarity Glycerol, has been identified in yeast. This pathway senses osmotic stress and invokes the cellular response, one aspect of which is the accumulation of intracellular glycerol (Brewster et. al, 1993). Mutations in the HOG pathway often cause an osmosensitive phenotype similar to that shown by ssv mutations. This work sets out to characterise several ssv strains for defects in the HOG pathway. These strains were subjected to osmotic stress and the intracellular and extracellular glycerol determined and compared to control strains and conditions. Many of the strains showed reduced, or even elevated in one case, glycerol levels compared to wild-type strains. No correlation could be made between these glycerol levels and the activity of the rate-limiting enzyme, glycerol-3-phosphate dehydrogenase (GPDH) determined in an independent study. Transcription of the GPDH gene is under the control of the HOG pathway. In a separate study, the nucleotide sequence of a short region of yeast chromosome VII was determined. Approximately 11,000 bases of DNA from the right sub-telomeric region was sequenced. Analysis of the DNA sequence showed four potential open reading frames. One of these encoded the YORl gene and another a protein related to PAU1 The remaining two ORFs, termed ORFl and ORF2, encoded potential proteins of unknown function. Disruption cassettes containing the LEU2 selectable marker were constructed for both ORFl and ORF2. Successful disruption of ORFl was achieved, but no viable transformants were ever recovered after attempted disruption of 0RF2..ORFl gene knockouts are viable and show no observable phenotype under a range of growth conditions. Subsequent analysis of ORFl and 0RF2 after the completion of the Yeast Genome Project, shows that both ORFl and 0RF2 are members of different sub- telomeric associated gene families. 0RF2 encodes a putative Y' protein.
54

Valorisation du glycérol par polycondensation catalytique / Valorization of glycerol by catalytic polycondensation

Monakhova, Julia 15 November 2012 (has links)
Ce travail de thèse s'inscrit dans le cadre de la valorisation du glycérol par polycondensation catalytique. L'objectif est l'obtention de nouveaux catalyseurs basiques hétérogènes actifs et sélectifs pour effectuer la polycondensation directe du glycérol en polymères contenant plus de 5 unités monomères, tout en évitant les sous-produits toxiques (acroléine) et les polymères cycliques. Des précurseurs de catalyseurs associant le lanthane et les différents cations alcalino-terreux ont été obtenus par co-précipitation conventionnelle ou par une voie originale utilisant des ionogels bi-cationiques d'alginate. L'influence de la méthode de préparation, de la température d'activation, de la nature et du contenu en cations alcalino-terreux sur les propriétés physico-chimiques (composition, nature des phases, surfaces spécifiques) et la basicité des catalyseurs a été étudiée. Elles ont été reliées à l'activité et la sélectivité des produits obtenus dans la réaction de polycondensation du glycérol effectuée à 533 K en réacteur batch. / This PhD work deals with the valorization of glycerol by catalytic polycondensation. The main objective is to obtain new heterogeneous basic catalysts, active and selective, able to perform the direct polycondensation of glycerol into polymers containing more than 5 monomer units, avoiding toxic by-products (acrolein) and cyclic polymers. Catalyst precursors involving lanthanum and the various alkaline earth metal cations have been obtained by conventional co-precipitation or by an original route using bi-cationic ionogels of alginate. The influence of the preparation method, the activation temperature, the nature and the content of alkaline earth cations on the physico-chemical properties (composition, nature of the phases, specific surface area) and the basicity of the catalysts was studied. They were related to the activity and selectivity of the products obtained in the polycondensation reaction of glycerol performed at 533 K in batch reactor.
55

Velmi rychlá elektroforetická stanovení klinicky významných látek v tělních tekutinách. / High-fast electrophoretic determinations of clinically important compounds in body fluids.

Málková, Klára January 2010 (has links)
A capillary electrophoretic procedure employing contactless conductivity detection (C4 D) has been developed for direct determination of the glycerol and mannitol polyalcohols in biological and pharmacological samples. Both glycerol and mannitol are fully separated from the sample matrix within very short times of 3.0 and 3.9 min., respectively, when using the optimized background electrolyte, 60 mM H3BO3 + 30 mM LiOH (pH 9.1). The limits of detection amount to 0.5 µM for glycerol and 0.3 µM for mannitol. The repeatability of the glycerol determination in real biological materials is characterized by the coefficient of variation values, 0.5 % and 3.2 %, for the migration time and the peak area, respectively. The procedure has been used to monitor the free glycerol concentration in adipose tissue microdialyzates. A physiological study has demonstrated that the lipolysis occurring during a sporting action can be stimulated by local application of adrenaline. The procedure has further been utilized to determine mannitol in a pharmacological preparation.
56

Catalisadores de Ni suportado em La2O3 e SiO2 aplicados na reação de reforma a vapor de glicerol / Ni supported on La2O3 e SiO2 used to catalyze glycerol steam reforming

Thyssen, Vivian Vazquez 19 April 2012 (has links)
Catalisadores de Ni suportado em La2O3, SiO2 e La2O3-SiO2 (com teores mássicos de La2O30 de 10%, 30% e 50%) tiveram seu desempenho avaliado frente a reação de reforma a vapor de glicerol. O efeito do suporte sobre a atividade, estabilidade e seletividade do catalisador foi avaliado, assim como diferentes métodos de preparo, teores de Ni e temperaturas de reação. Os catalisadores foram preparados pelos métodos da impregnação úmida seqüencial, impregnação úmida simultânea, impregnação sobre o suporte precipitado e co-precipitação, utilizando teores mássicos de 5%, 10% e 15% de Ni. Foram utilizadas as seguintes técnicas de caracterização: espectroscopia de energia dispersiva de raios X, fisissorção de nitrogênio, difratometria de raios X, redução a temperatura programada e difração de raios X in situ. Os catalisadores foram testados por um período de 5h, a fim de verificar a atividade e seletividade para a reação de reforma a vapor de glicerol a 500°C, 600°C e 700°C, e as propriedades dos catalisadores foram correlacionadas com os resultados obtidos dos ensaios catalíticos. Após as reações, os catalisadores foram submetidos as seguintes análises: análise elementar, difratometria de raios X e microscopia eletrônica de varredura. Foi observado que o Ni interage de forma variada com os diferentes suportes, que o método de preparação utilizado influencia propriedades dos catalisadores e que, dependendo do teor mássico de Ni suportado, o catalisador pode ser mais ou menos ativo para a reação de reforma a vapor de glicerol. Observou-se também que a temperatura influencia no desempenho da reação, sendo que os melhores resultados foram obtidos a 600°C com o catalisador 15Ni30LaSi preparado por impregnação úmida simultânea, que foi testado também por 20h para que fosse analisada sua estabilidade em um maior intervalo de tempo. / Ni catalysts supported on La2O3, SiO2 and La2O3-SiO2 (with 10%, 30% and 50%wt.La2O3) were evaluated in the glycerol steam reforming reaction. The effect of the supports was analyzed on the catalysts activity; stability and selectivity as well as different methods of preparation, Ni contents and reaction temperatures. Catalysts were prepared by the sequential wet impregnation, simultaneous wet impregnation, impregnation of Ni on support precipitate and co-precipitation methods using 5%, 10% and 15%wt.Ni. The catalysts were characterized by energy dispersive X-ray spectroscopy, nitrogen physisorption, X-ray diffraction, temperature programmed reduction and X-ray diffraction in situ. The catalytic tests were performed during 5 hours in order to verify the activity and selectivity for the glycerol steam reforming at 500°C, 600°C and 700°C, and identify the relationship between the catalysts properties and the results obtained with the catalytic tests. After the reactions, the catalysts were characterized by elemental analysis, X-ray diffraction and scanning electron microscopy. It was observed that the Ni interacted variously with different supports; the preparation method used influenced on the catalysts properties and, depending on the Ni content, the catalyst was more or less active for the glycerol steam reforming. It was also observed that the temperature of reaction influenced on the reaction performance, and the best results were obtained at 600°C with the 15Ni30LaSi catalyst, prepared by simultaneous wet impregnation, which was also tested for 20 hours to analyze its stability in a longer period.
57

Estudos da atividade de catalisadores a base de níquel, suportados em carbono, para a eletrooxidação do glicerol / Studies of the activity of nickel based catalysts, supported on carbon, toward glycerol electrooxidation

Oliveira, Vanessa Luciane 06 December 2013 (has links)
Catalisadores de Ni suportados em carbono foram sintetizados por diferentes rotas e avaliados frente a oxidação de glicerol em meio alcalino. O método de impregnação química, seguido de um tratamento térmico em uma atmosfera redutora de H2 por 2 horas, foi escolhido por fornecer um material mais ativo, e através deste método materiais como CoNi, FeNi, FeCoNi contendo 20% de metal foram sintetizados. As amostras foram caracterizadas por Análise Termogravimétrica (TGA-DTA) e Difração de Raios X (XRD) para verificar a quantidade de metal e tamanho de cristalito médio, respectivamente. Ensaios eletroquímicos de Voltametria Cíclica (CV) foram realizados para avaliar a atividade eletroquímica dos catalisadores frente a reação de oxidação do glicerol. Os resultados demonstram que a espécie oxihidróxido de níquel β-NiOOH foi a espécie catalítica ativa frente a oxidação de glicerol em meio alcalino. Como a formação de oxihidróxidos de cobalto e ferro ocorrem em potenciais mais baixos que o níquel, estes elementos adicionaram mudanças no perfil observado para o Ni/C. Estudos em condições controladas também foram feitos através de Voltametria Cíclica. O processo de oxidação do glicerol foi influenciado pela velocidade de varredura, temperatura e concentração do NaOH e glicerol. A relação linear entre a corrente de pico e a raiz quadrada da velocidade de varredura corresponde a um processo controlado por difusão. Verificou-se que ambos os Ipico e Epico são fortemente dependentes da concentração do glicerol. Em um potencial selecionado, experimentos de cronoamperometria foram realizados e os produtos de reação analisados por cromatografia líquida de alta eficiência (HPLC). A conversão do glicerol bem como a seletividade dos produtos formados depende da composição do catalisador. A distribuição de produtos foi correlacionada com os dados de espectroscopia de infravermelho (FTIR), os quais suportam o mecanismo de reação proposto. / Carbon supported nickel nanomaterials were synthesized by different routes and evaluated toward the oxidative transformation of glycerol in alkaline medium. The impregnation method, followed by heat-treatment in reducing H2 atmosphere for 2 hours, was chosen by providing a more active material. This method was used to prepare catalysts with metal loadings of 20 wt. %, such as CoNi/C, FeNi/C and FeCoNi/C. Physical characterizations of the materials were performed by using Thermogravimetric Analysis-Differential Thermal Analysis (TGA-DTA) and X-Ray Diffraction (XRD) to determine their metallic load and the crystallite size, respectively. Cyclic voltammetry was mainly used to evaluate the electrochemical activity of the catalysts for glycerol oxidation reaction. The results demonstrated that nickel oxyhydroxide, β-NiOOH, is the active catalytic specie for the glycerol oxidation reaction in alkaline medium. Since the formation of cobalt and iron oxy-hydroxides occurs at lower potentials than those of nickel, amounts of cobalt and iron were added to modify the Ni material. Studies under several well defined experimental conditions were performed by Cyclic Voltammetry. The process of glycerol oxidation was influenced by the scan rate, temperature, glycerol and NaOH concentration. The linear relationship between the peak current density and square root of scan rate corresponds to a diffusion-controlled process for glycerol oxidation on Ni/C. It was found that both the Ipeak and Epeak are strongly depending on the glycerol concentration. In a selected potential chronoamperometry experiments were carried out and the glycerol oxidation products on the Ni-based anodes were analyzed by High-Performance Liquid Chromatography (HPLC). The glycerol conversion depends on the catalyst composition and the distribution. The products were correlated with those identified by infrared reflectance spectroscopy, which supported the simplified mechanism proposed.
58

Suplementação de glicerina na dieta de equinos / Glycerin supplementation in equine diet

Mazzo, Hortencia Campos 02 March 2018 (has links)
A glicerina, na alimentação, pode ser considerada uma boa fonte energética. Assim, sua utilização como substituta em parte de grãos e outros alimentos ricos em amido é amplamente estuda já que esses alimentos podem causar alterações metabólicas e digestivas quando em alto consumo. Neste estudo, objetivou-se comparar níveis de adição de glicerina na dieta de equinos. Foram utilizados oito pôneis machos, castrados, da raça Mini-Horse, com idade aproximada de 9 anos ± 6 meses, peso corporal médio de 149,80 ± 17,20 kg e escore corporal médio de 5,4 ± 0,7. Os animais foram alojados em baias individuais. Adotou-se consumo diário individual de 1,75% do peso corporal (PC), sendo 1% do PC em matéria seca (MS) proveniente do volumoso e 0,75% do PC em MS do concentrado, com proporção 60:40 (volumoso:concentrado). O delineamento experimental utilizado foi o quadrado latino duplo 4 x 4 contemporâneos. As dietas diferiram quanto ao nível de inclusão de glicerina (0, 4, 8 e 12%) que foram calculados com relação á porcentagem de concentrado fornecidos por animal. As avaliações foram realizada em quatro períodos, sendo 14 dias de adaptação à dieta, 5 dias de coleta total de fezes (CTF) e 2 semanas de intervalo entre os períodos. Avaliou-se a digestibilidade aparente total dos nutrientes e fermentabilidade da glicerina a partir da CTF, por meio das análises de respostas glicêmicas, insulinêmicas, ácido graxos da cadeia curta, ácidos graxos não esterificados (NEFA) e pH das fezes. Também foram realizadas análises de segurança e aceitabilidade que se constituiu de análises de função hepática e renal, triglicerídeos, colesterol e frações além da avaliação do comportamento alimentar dos animais. Além de análise de implicações econômica a partir da simulação de substituição do milho pela glicerina bruta. Os dados foram submetidos à análise pelo programa Statistical Analysis System (SAS Institute Inc., 2010). Para os resultados significativos, foi utilizado o teste de Tukey com P<0,05. Não houve diferenças entre os tratamentos em nenhuma das análises realizadas (P<0,05). A glicerina se mostrou palatável e com aceitabilidade. A substituição de milho por glicerina, mesmo em valores de 1%, representa economicamente 0,42% de ganho. A suplementação de glicerina bruta na dieta de equinos se apresenta como segura não afetando o comportamento alimentar, a higidez e a saúde digestiva dos animais, possuindo justificativa econômica para uso. / Glycerin in food can be considered a good source of energy. Thus, its use as a substitute part of grains and other starchy foods is widely studied since these foods can cause metabolic and digestive changes when in high consumption. The objective of this study was to compare levels of glycerin addition in the equine diet. Eight male, castrated Mini-Horse male ponies, aged approximately 9 years ± 6 months, mean body weight of 149.80 ± 17.20 kg and mean body score of 5.4 ± 0.7 were used. The animals were housed in individual stalls. Individual daily consumption of 1.75% of body weight (CP) was used, with 1% CP in dry matter (DM) from bulky and 0.75% CP in DM from concentrate, with a ratio of 60:40 voluminous: concentrate). The experimental design used was the contemporary 4 x 4 double Latin square. The diets differed in the glycerin inclusion levels (0, 4, 8 and 12%) that were calculated in relation to the percentage of concentrate supplied per animal. The evaluations were performed in four periods, 14 days of adaptation to the diet, 5 days of total collection of feces (TCF) and 2 weeks of interval between periods. The total apparent digestibility of nutrients and fermentability of glycerol from the TCF were evaluated through glycemic, insulinemic, short chain fatty acid, non-esterified fatty acid (NEFA) and faecal pH analyzes. Safety and acceptability analyzes were also performed, which consisted of analyzes of liver and renal function, triglycerides, cholesterol and fractions, besides the evaluation of the animals\' feeding behavior. In addition to analysis of economic implications from the simulation of substitution of corn by crude glycerin. The data were submitted to analysis by the Statistical Analysis System (SAS Institute Inc., 2010). For the significant results, the Tukey test was used with P <0.05. There were no differences between treatments in any of the analyzes performed (P <0.05). Glycerin was palatable and acceptable. The substitution of corn for glycerin, even at 1%, represents economically 0.42% gain. The supplementation of crude glycerin in the equine diet presents itself as safe, without affecting the alimentary behavior, the hygiene and the digestive health of the animals, with economic justification for use.
59

Estudo cinético da produção de exopolissacarídeo por Lasiodiplodia theobromae em biorreator agitado e aerado de baixo cisalhamento / Kinetic study of the production of exopolysaccharide by Lasiodiplodia theobromae in agitated and aerated low shear bioreactor

Tabuchi, Stéphanie Caroline Tavares 10 November 2017 (has links)
Os polissacarídeos possuem diversas aplicações industriais devido a sua ampla variedade de propriedades físico-químicas. Além desses empregos tradicionais, pesquisas mais recentes estão impulsionando o uso de polissacarídeos para novas aplicações, principalmente na área de terapia farmacêutica. Com o objetivo de ampliar a produção industrial de polissacarídeos microbianos, pesquisas têm se concentrado nos exopolissacarídeos (EPS), que apresentam produtividade elevada e processos de extração e purificação mais simples quando comparados aos polímeros tradicionais. A lasiodiplodana, uma ?-(1->6)-D-glucana, é um EPS produzido por Lasiodiplodia theobromae, um fungo filamentoso característico de regiões tropicais e patógeno de mais de 500 espécies vegetais. Na produção de EPS observa-se que, como resultado do crescimento e da produção do biopolímero, o meio de cultivo torna-se mais viscoso, tornando difícil a manutenção da homogeneidade no biorreator e, consequentemente, prejudicando a transferência de massa e oxigênio no meio. Nos cultivos em que ocorrem mudanças na reologia do meio e nos quais são utilizados fungos filamentosos, sensíveis ao cisalhamento, o uso de biorreatores convencionais, como o Stirred Tank Reactor (STR) e o Airlift, não é adequado. Nesse contexto, no presente estudo tem-se como objetivo estudar a cinética de crescimento, consumo de substrato e produção de EPS pelo fungo filamentoso Lasiodiplodia theobromae, a partir de glicose e de glicerol, no Biorreator Agitado e Aerado de Baixo Cisalhamento (BAABC) e compará-lo com o STR. No estudo inicial, realizado em frascos agitados, a maior produção de EPS (6,49 ± 0,03 g/L) foi alcançada pelo ensaio G, que continha a maior concentração glicose testada (50 g/L) e a menor concentração de extrato de levedura (3 g/L). Quando se utilizou glicerol como fonte de carbono, a maior produção de EPS (3,39 ± 0,06 g/L) foi observada no Ensaio O, que continha 30 g/L de glicerol e a maior concentração de fonte de nitrogênio testada (12 g/L de extrato de levedura). Nos ensaios em biorreatores, quando utilizou-se glicose como fonte de carbono observou-se que o BAABC com controle de temperatura proporcionou uma produção de 3,17 ± 0,16 g/L de EPS, concentração inferior à obtida em frascos, porém bastante superior à obtida no biorreator STR (0,70 ± 0,12 g/L). Para os meios contendo glicerol, o biorreator STR proporcionou uma produção de EPS de 3,02 ± 0,19 g/L, enquanto no BAABC a concentração de EPS obtida foi muito menor (1,45 ± 0,25 g/L). Analisando-se, porém, a concentração máxima de biomassa obtida (28,86 ± 1,46 g/L) bem como os parâmetros cinéticos relacionados (YX/S e QX), nota-se que a produção de biomassa foi muito superior e mais eficiente no BAABC. Apesar das diferenças morfológicas visualmente observadas e confirmadas por meio de microscopia óptica nos EPS obtidos a partir de glicose e de glicerol, as análises de Difração de raios-X e Espectroscopia de absorção na região do infravermelho com Transformada de Fourier permitiram evidenciar a similaridade estrutural entre ambos os EPS. / Polysaccharides have several industrial applications because of their wide variety of physicochemical properties. In addition to these traditional applications, recent research is driving the use of polysaccharides towards new applications, especially in the field of pharmaceutical therapy. With the aim of increasing the industrial production of microbial polysaccharides, research has focused on exopolysaccharides (EPS), which have high productivity and simpler extraction and purification processes when compared to traditional polymers. Lasiodiplodana, a ?-(1->6)-D-glucan, is an EPS produced by Lasiodiplodia theobromae, a filamentous fungus characteristic of tropical areas and pathogenic of more than 500 plant species. In EPS production, as a result of the growth and biopolymer production, the culture medium becomes more viscous, making it difficult to maintain homogeneity inside the bioreactor and, consequently, harming the transfer of mass and oxygen in the medium. In cultures where changes in media rheology occur and in which shear-sensitive filamentous fungi are used, the use of conventional bioreactors, such as Stirred Tank Reactor (STR) and Airlift, is not appropriate. In this context, the objective of the present study was to study the growth kinetics, substrate consumption and EPS production by the Lasiodiplodia theobromae filamentous fungus, from glucose and glycerol, in the Low-Shear Aerated-Agitated Bioreactor (LSAAB) and compare it with the STR. In the initial study, conducted in shaken flasks, the highest EPS production (6.49 ± 0.03 g/L) was achieved by the G test, which contained the highest glucose concentration tested (50 g/L) and the lowest concentration of yeast extract (3 g/L). When glycerol was used as the carbon source, the highest EPS yield (3.39 ± 0.06 g/L) was observed in Test O, which contained 30 g/L glycerol and the highest concentration of nitrogen source tested (12 g/L of yeast extract). In the bioreactor trials, when glucose was used as the carbon source, it was observed that the LSAAB with temperature control provided a production of 3.17 ± 0.16 g/L of EPS, a concentration lower than that obtained in flasks, but rather higher than that obtained in the STR bioreactor (0.70 ± 0.12 g/L). For the glycerol-containing media, the STR bioreactor produced 3.02 ± 0.19 g/L of EPS, while in LSAAB the EPS concentration obtained was much lower (1.45 ± 0.25 g/L). However, analyzing the maximum concentration of biomass obtained (28.86 ± 1.46 g/L) as well as the related kinetic parameters (YX/S and QX), biomass production was much higher and more efficient in LSAAB. In spite of the visually observed morphological differences confirmed by optical microscopy in EPS obtained from glucose and glycerol, X-ray diffraction and absorption spectroscopy analyzes in the infrared region with Fourier transform showed the structural similarity between both EPS.
60

Líquidos iônicos na produção catalítica de biodiesel etílico e aditivos / Ionic liquids in catalytic production of ethyl biodiesel and additives

Zanin, Fabio Graziane 18 June 2012 (has links)
A produção de biodiesel etílico é uma questão estratégica para a política energética nacional, uma vez que o Brasil é um dos maiores produtores de oleaginosas do mundo e o segundo maior produtor de etanol, álcool de origem renovável. Neste sentido, o presente trabalho buscou promover a transesterificação de óleos vegetais por etanol assistido por líquidos Iônicos sob diferentes fontes de aquecimento. O glicerol foi transformado em compostos de valor agregado e de interesse industrial. O mesmo foi modificado in situ após a reação de transesterificação gerando biodiesel aditivado pelos derivados da glicerina, conforme esquema 1. (Ver arquivo) / The production of ethyl biodiesel is a strategic issue for the national energy policy, because Brazil is one of the largest producers of oilseeds and the second largest producer of ethanol, a renewable alcohol. In this way, this work aimed to promote the transesterification of vegetable oils with ethanol assisted by ionic liquids under different heat sources. Glycerol was transformed into valuable compounds of industrial interest. It was also modified in situ after the transesterification reaction generating additive ethyl biodiesel, as shown below. (See file)

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