Recently, clathrate hydrate has attracted much attention because of its energy gas enclathration phenomenon. Since energy gas such as methane, ethane, and hydrogen could be stored in solid hydrate form, clathrate hydrate research has been considerably focused on energy gas storage and transportation medium. Especially, methane hydrate, which is crystalline compound that are formed by physical interaction between water and relatively small sized guest molecules, can contain about as much as 180 volumes of gas at standard pressure and temperature condition. To utilize gas hydrate as energy storage and transportation medium, two important key features: storage capacity and storage condition must be considered. Herein, we report the inclusion phenomena of methane occurred on tert-butyl alcohol hydrate through thermodynamic measurement and spectroscopic analysis by using powder X-ray diffractometer, and 13C solidstate NMR. From spectroscopic analysis, we found the formation of sII type (cubic, Fd3m) clathrate hydrate by introducing methane gas into tert-butyl alcohol hydrate whereas tert-butyl alcohol hydrate alone does not form clathrate hydrate structure. Under equilibrium condition, pressure-lowering effect of methane + tert-butyl alcohol double hydrate was also observed. The present results give us several key features for better understanding of inclusion phenomena occurring in the complex hydrate systems and further developing methane or other gas storage and transportation technique.

Objetivo del trabajo: Evaluar el éxito del tratamiento con butyl cianoacrilato en la hemostasia primaria, el resangrado y la erradicación de varices gástricas. Materiales y Metodos: Desde enero de 1999 a enero de 2008 fueron analizados en forma retrospectiva 65 casos de pacientes con varices gástricas que fueron tratados en nuestra unidad con N-Butyl-2-cianoacrilato (Histoacryl®). Se utilizó una solución de 0.5 ml histoacryl y 0.8 ml de lipiodol con un promedio de 3.46 ml de dicha mezcla por sesión (rango: 1 a 6 ml). Se emplearon agujas de esclerosis de 21 gauge, y neuroleptoanalgesia. Los datos se analizaron con el test de chi-cuadrado.

Darbo tikslas – ištirti rapsų aliejaus peresterinimo procesą naudojant biobutanolį, įvertinti gauto biodyzelino savybes ir poveikį aplinkai. Darbo objektas – rapsų aliejaus riebalų rūgščių butilesteriai, gauti po rapsų aliejaus peresterinimo biobutanoliu. Darbo metodai – rapsų aliejaus peresterinimas butanoliu atliktas biotechnologiniu metodu, naudojant biokatalizatorių Lipozyme TL IM. Peresterinimo laipsnis, butilesterių ir parcialinių gliceridų kiekis nustatyti plonasluoksnės ir dujų chromatografijos metodais. Gauto biodyzelino savybės įvertintos pagal standarte LST EN 14214 pateiktas metodikas. Variklio eksploataciniai ir deginių emisijų tyrimai VGT universitete atlikti 1992 m. gamybos ,,Audi-80‘‘ automobilio dyzeliniu varikliu. Variklio išmetamųjų dujų analizei naudotas išmetamųjų dujų analizatorius AVL DiCom 4000. Biologinis degalų suirimas atliktas taikant OECD 301 F ,,Manometrinės respirometrijos‘‘ metodą AL 606 prietaisu. Darbo rezultatai. Nustatytos optimalios 2 stadijų rapsų aliejaus peresterinimo butanoliu proceso sąlygos. Pagaminti rapsų aliejaus riebalų rūgščių butilesteriai (RBE) atitinka standarto LST EN 14214 reikalavimus. Grynų butilesterių atsparumą oksidacijai daugiau kaip 6 val. padidina antioksidantas – IONOL BF 200 (2000 ppm). Vasaros ir pereinamuoju laikotarpiu gryni butilesteriai ir jų mišiniai su žieminiu dyzelinu ir butanoliu tinkami naudoti be specialių priedų. Maišant rapsų aliejaus riebalų rūgščių butilesterius su žieminiu dyzelinu ir butanoliu... [toliau žr. visą tekstą] / Aim of the work – to analyze the process of rapeseed oil transesterification by using biobutanol, to evaluate the characteristics of the derived biodiesel and its impact on the environment. Object of research – butyl esters of rapeseed oil received after the transesterification of rapeseed oil using biobutanol. Research methods – transesterification of rapeseed oil using biobutanol has been performed by applying biotechnological method, using biocatalyst Lipozyme TL IM. The level of transesterification and quantity of butyl esters and partial glycerides has been determined by methods of thin-layer and gas chromatography. The characteristics of the derived biodiesel have been evaluated according to the methodology provided by standard LST EN 14214. The analysis of engine exploitation and environmental characteristics have been performed at VGT university on the diesel engine of 1992 “Audi-80”. For the analysis of exhaust gases of engine the gas analyzer AVL DiCom 4000 has been used. Degradation of biological fuel has been performed according to OECD 301 F “Manometric respirometry” using AL 606 device. Results of research. Optimal conditions of 2-stage rapeseed oil transesterification process using butanol. Were determined the produced butyl esters of rapeseed oil meet the requirements of LST EN 14214 standards. Antioxidant JONOL BF 200 increases the oxidative stability of pure butyl esters. In summer or during transition period pure butyl esters and their mixtures with... [to full text]

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Poly (co iso-butyl vinyl ether-alt-maleic anhydride), an alternating copolymer, was synthesised. For this class of copolymers the formation of an electron-donor complex is invoked to explain their microstructure in which the two comonomers strictly alternate. Due to its polarity, this copolymer constitutes a potential additive for imparting hydrophilic properties to a hydrophobic matrix. In order to obtain narrow molecular weight polymers and study the relation between the molecular weight of this additive and its ability to migrate to the host polymer surface, chain transfer agents were introduced in the system and also the Reversible Addition-Fragmentation chain Transfer (RAFT) process was employed. Free radical polymerisation was first carried out to allow for a comparison with the RAFT process and kinetics of copolymerisation was studied by NIR-FTIR and 1H NMR spectroscopy in order to analyse the rate of reaction of each comonomer. Dibenzyl trithiobenzoate, 3-benzyl sulfanyl thiocarbonyl sulfanyl-propionic acid and dibenzyl trithiobenzoate were used as RAFT agents. Results demonstrate that only benzyl dithiobenzoate is able to control the molecular weight of this copolymer and decrease its polydispersity index; possible reasons laying behind this result are discussed. It was also found that, in particular in the presence of benzyl dithiobenzoate, poly(iso-butyl vinyl ether) forms. This is an unusual phenomenon considering that the free radical polymerisation affords alternating copolymers and that iso-butyl vinyl ether is a monomer that polymerises through the cationic process. Experiments were carried out in various solvents in an attempt to counteract this side reaction, but no appreciable correlation between the properties of the solvents and the formation of homopolymer were found. Various hypothesis are considered, however it is likely that, in the conditions adopted, the presence of the RAFT agents alters the equilibrium constant of complex formation favouring the synthesis of the homopolymer. In addition to this side???reaction also inhibition of the copolymerisation reaction was at times encountered and an investigation into this phenomenon was also conducted.

Thesis (Ph. D.)--Rutgers University, 2010. / "Graduate Program in Environmental Sciences." Includes bibliographical references (p. 141-155).

Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: Water; Adsorption; Molecular simulation; Nanoporous materials. Includes bibliographical references (p. 117-119).

This study investigates the occurrence of di-butyl phthalate (DBP) and di-ethylhexyl phthalate (DEHP) in raw cow's milk. The idea was to compare level of contamination in manually and mechanically obtained milk. Samples were collected at a farm in the Vysočina region in January and April 2013. The concentrations of DBP and DEHP were determined by high performance liquid chromatography. Throughout the experiment a statistically significantly higher content of DBP than DEHP was observed. The concentration of DBP ranged from 0,57 to 16,79 mg.kg-1 of milk, DEHP ranged from undetectable values to 0,39 mg.kg-1 of milk. The amount of phthalates in the mechanically obtained milk was approximately two times higher than in the milk milked by hand, probably due to migration from the contact materials of the milking equipment. In April a slight decrease in the concentration values was observed, but the values did not differ statistically significantly from the values measured in January. The presence of phthalates in milk on the primary production level is a shining example of their wide application, which burdens the environment and the food chain.

Os processos industriais de polimerização em emulsão são normalmente realizados em reatores batelada ou semi batelada ou em tanques agitados contínuos (CSTR). Os reatores contínuos têm a vantagem de terem menor porte e de propiciarem melhor controle de qualidade do produto através da redução de variações de batelada a batelada. Além disso, as oscilações periódicas autosustentadas na conversão de monômero e no tamanho da partícula, que são normalmente observadas em reatores do tipo CSTR, podem ser minimizadas em reatores tubulares mediante o uso de dispositivos de mistura estáticos adequados combinados com escoamento pulsado (oscilatório). O objetivo deste trabalho é apresentar o desenvolvimento de uma copolimerização em emulsão de acetato de vinila e acrilato de butila em uma coluna pulsada com pratos perfurados (CPPP). A fim de aumentar a sua flexibilidade operacional, a coluna é composta de 5 seções, cada uma apresentando controles independentes de alimentação lateral e temperatura. Dependendo da estratégia de alimentação de monômero, pode-se notar uma deriva de composição durante o processo de copolimerização em emulsão do acetato de vinila e acrilato de butila devido às grandes diferenças entre estes monômeros em suas razões de reatividade e nas solubilidades na fase aquosa. Neste caso, a CPPP propicia diferentes possibilidades de alimentação que permitem controlar a composição do copolímero através da alimentação do monômero mais reativo ao longo da coluna. Por esta razão, foi avaliado neste estudo o efeito do número de correntes de alimentação sobre as propriedades do polímero. Diferentes números de correntes laterais de alimentação de monômero foram empregadas nos ensaios experimentais. Diferenças na uniformidade da composição do copolímero podem ser notadas dependendo do número de correntes laterais de alimentação aplicadas em cada teste. A fim de permitir variações de temperatura, somente a temperatura de entrada das camisas de resfriamento foi fixada. Para simular as reações foi utilizado um modelo matemático desenvolvido baseado no modelo de escoamento pistonado (plug-flow) axialmente disperso. No presente trabalho, um balanço de energia foi incluído ao modelo matemático anterior de modo que a influência de diferentes perfis de temperatura pudesse ser considerada. O efeito das correntes laterais de alimentação de monômero sobre as propriedades do copolímero puderam ser previstas com suficiente precisão pelas simulações do modelo, as quais foram também validadas pelos resultados experimentais. Com base nas simulações matemáticas, um perfil ótimo de alimentação pôde ser calculado e experimentalmente aplicado na CPPP permitindo a produção de um copolímero mais homogêneo. Os resultados também permitiram a validação do modelo matemático como uma ferramenta confiável na predição de ensaios experimentais. Além disso, as vantagens da CPPP puderam ser verificadas pelo seu desempenho adequado como reator tubular para processos contínuos de copolimerização em emulsão. Finalmente, os resultados indicaram a possibilidade de melhorias adicionais nas propriedades do polímero através do emprego de diferentes temperaturas e perfis de alimentação de outros reagentes ao longo da coluna. / Industrial emulsion polymerization processes are usually performed in batch or semi-batch stirred tanks, or in continuous stirred tank reactors (CSTR). Continuous reactors have the advantage of being smaller and providing a better product quality control by the reduction of the batch-to-batch variations. In addition, periodical self-sustained oscillations in monomer conversion and in particle size that are usually observed in CSTR can be minimized in tubular reactors presenting good radial mixing. Such conditions can be achieved in tubular reactors by using adequate static mixing devices combined with pulsed (oscillatory) flow. The aim of this work is to report the development of a continuous emulsion copolymerization of vinyl acetate and butyl acrylate performed in a pulsed sieve plate column (PSPC). In order to improve its operational flexibility, the column is composed of five sections, each one presenting independent lateral feed and temperature controls. Depending on the monomer feeding strategy, a composition drift can be noticed during the emulsion copolymerization process of vinyl acetate and butyl acrylate, due to the large differences in reactivity ratios and aqueous phase solubility between these monomers. In this case, the PSPC provides different operational feeding possibilities which allow controlling the copolymer composition by feeding the more reactive monomer along the column. For this reason, in this study the effect of the number of lateral feed streams on the polymer properties was evaluated. Different numbers of lateral monomer feed streams were employed in the experimental runs. Differences in the uniformity of the copolymer composition can be noticed along the reactor depending on the number of lateral feed streams applied in each test. In order to allow temperature variations, during each reaction only the inlet temperature of the cooling jackets was fixed. A developed mathematical model based on the axially dispersed plug-flow model was used to simulate the reactions. In the present study the energy balance was included in the mathematical model so that the influence of different temperature profiles could be taken into account. The effect of lateral monomer feed streams over the copolymer properties could be predicted with sufficient accuracy by model simulations which were also validated by the experimental results. Based on mathematical simulations, an optimal feeding profile could be calculated and experimentally applied in the PSPC allowing the production of a more homogeneous copolymer. The results also permitted the validation of the mathematical model as a reliable tool in the prediction of experimental runs. Furthermore, the advantages of the PSPC could be verified by its adequate performance as a tubular reactor for continuous emulsion copolymerization processes. Finally, the results indicate the possibility of further improvements in other polymer properties by employing different temperature and feeding profiles of other reagents along the column.

Os ésteres são importantes compostos orgânicos, obtidos por síntese química ou extraídos de alguns produtos naturais utilizando-se solvente em meio adequado. Estudos mostram que enzimas, em particular lipases, podem ser aplicadas na síntese de diversos ésteres. O principal objetivo deste trabalho foi a obtenção de acetato de butila, um éster de aroma característico de abacaxi, utilizando lipase de Geotrichum candidum produzida em fermentação submersa e imobilizada em matriz polimérica de alginato de bário e gelatina reticulada com glutaraldeído. A caracterização bioquímica foi realizada tanto para a lipase na forma livre como para a lipase na forma imobilizada. O rendimento em conversão molar de substrato foi determinado por cromatografia gasosa. A enzima apresentou atividade enzimática máxima após 48 horas de fermentação de 37,7 U/mL. Os valores ótimos para pH e temperatura da enzima na forma livre e imobilizada foram pH 6,5 e 40 °C e pH 7,5 e 45 °C, respectivamente. A enzima na forma livre foi estável do pH 6,0 ao 8,0 e à temperatura de 35 a 45 °C, já na forma imobilizada, foi estável do pH 5,5 ao 8,5 e na faixa de temperatura de 30 a 55 °C. A lipase imobilizada teve seus parâmetros cinéticos determinados, e os valores obtidos para o Km e Vmax, foram 0,115 mmol e 0,718 µmol.mL-1.min-1, respectivamente. As melhores condições de síntese do bioaroma para a enzima na forma livre foram: temperatura de 30 °C, 12,5% de enzima em relação à quantidade de butanol utilizada, proporção molar do substrato 60% de acetato de vinila em um período de 24 horas. O rendimento alcançado neste caso foi de 97,2 % de conversão molar em acetato de butila. Para a enzima imobilizada as melhores condições foram: temperatura de 45 °C, 12,5% de enzima em relação à quantidade de butanol utilizada, proporção molar do substrato 60% de acetato de vinila em um período de 24 horas. O rendimento alcançado neste caso foi de 99,1%, que demonstra que lipase produzida por Geotrichum candidum na forma imobilizada apresenta excelente capacidade de sintetizar acetato de butila (bioaroma de abacaxi). / Esters are important organic compounds obtained by chemical synthesis or derived from some natural products using a solvent in appropriate medium. Studies have shown that enzymes, particularly lipases, ca be applied in the synthesis of various esters. The main objective of this study was to obtain butyl acetate, a characteristic ester aroma of pineapple, using lipase from Geotrichum candidum produced in submerged fermentation and immobilized in a barium alginate and gelatin polymer matrix crosslinked with glutaraldehyde. The biochemical characterization was performed for both free and immobilized lipases. The yield in molar conversion of substrate was determined by gas chromatography. The enzyme showed maximum enzymatic activity after 48 hours of fermentation of 37.7 U/mL. The optimum values for pH and temperature of the enzyme in free and immobilize form were pH 6.5 and 40 °C and pH 7.5 and 45 °C, respectively. The enzyme was stable in free form from pH 6.0 to 8.0 and at temperatures from 35 to 45 °C, and in the immobilized form from pH 5.5 to 8.5 and at temperatures from 30 to 55 °C. Kinetic parameters of the immobilized lipase were determined, and the values obtained for Km and Vmax were 0.115 mmol and 0.718 µmol.mL-1.min-1, respectively. The best conditions for the synthesis of flavor by enzyme in free form were: 30 °C of temperature, 12.5% of enzyme for the amount of butanol used, and molar ratio of substrate 60% of vinyl acetate in a 24 hours period. The yield achieved in this case was 97.2% of molar conversion in butyl acetate. For the immobilized enzyme the best conditions were: 45 °C of temperature, 12.5% of enzyme for the amount of butanol used, and molar ratio of substrate 60% of vinyl acetate in a 24 hours period. The yield achieved in this case was 99.1%, demonstrating that lipase produced by Geotrichum candidum in immobilized form has an excellent ability to synthesize butyl acetate (pineapple flavor).