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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.
101

Produção e extração de colorantes naturais de Penicillium purpurogenum DPUA 1275 / Production and extraction of natural colorants from Penicillium purpurogenum DPUA 1275.

Santos-Ebinuma, Valéria de Carvalho 08 March 2013 (has links)
Há interesse mundial no desenvolvimento de pesquisas envolvendo produção e extração de colorantes naturais, devido a sérios problemas de segurança industrial associados ao uso de colorantes sintéticos. Este trabalho objetivou produzir colorantes naturais de Penicillium purpurogenum DPUA 1275 por cultivo submerso (em frascos agitados e em biorreator) e estudar a extração dos colorantes vermelhos. Para a produção, os estudos iniciais mostraram que 5 discos de micélio, sacarose e extrato de levedura como fontes de carbono e nitrogênio, respectivamente, e 336 horas de cultivo eram condições adequadas para a produção dos colorantes. Visando à otimização da produção, realizaram-se planejamentos fatoriais, com as variáveis independentes: tempo de cultivo; velocidade de agitação; pH; temperatura; concentração de sacarose e de extrato de levedura. As variáveis-respostas foram produção de colorantes amarelos, laranjas e vermelhos. Dos resultados obtidos, as variáveis mais significativas ao processo foram concentrações de extrato de levedura e de sacarose. A produção dos colorantes vermelhos foi otimizada, alcançando a produção de 2,97 UA490nm, nas condições 48,90 e 11,80 g/L de sacarose e extrato de levedura, respectivamente, 30°C, pH 4,5 150 rpm e 336 horas de cultivo. Nos experimentos em biorreator, o melhor resultado foi obtido na frequência de agitação de 500 rpm e na mudança do pH do meio para 8,0, após 96 horas de bioprocesso. Ademais, avaliou-se a estabilidade dos colorantes vermelhos presentes no meio fermentado em diferentes condições (pH, temperatura, sais, polímeros e tensoativos). Referente a pH e temperatura, os colorantes vermelhos mostraram-se mais estáveis nas condições alcalinas e a 70 °C. Tanto os sais (NaCl e Na2SO4) quanto os polímeros (PEG 1.000, 6.000 e 10.000 g/mol e NaPA 8.000 g/mol a 5 e 15%) e os tensoativos (Tween 20, CTAB e SDS) não causaram perda da cor nas condições avaliadas. Estudos de solubilidade e de coeficiente de partição octanol-água mostraram que os colorantes vermelhos apresentam solubilidade superior em solventes polares e característica mais hidrofílica. Nos estudos de extração, as técnicas avaliadas foram Sistemas Poliméricos de Duas Fases Aquosas (SPDFA) formados pelo sistema PEG/NaPA e Colloidal Gas Aphrons (CGA). Pela primeira técnica, os colorantes vermelhos migraram preferencialmente para a fase PEG. Os polímeros PEG 6.000 g/mol, na presença de NaCl 0,1 e 0,5 M, e PEG 10.000 g/mol, com Na2SO4 0,5M, se destacaram dentre as condições analisadas com coeficiente de partição (K) próximo a 13, em ambos os casos, e seletividade de proteínas (SeP) próximas a 3. Para a técnica de CGA, o CTAB proporcionou os melhores resultados, seguido do Tween 20. Porém, o valor de K foi inferior ao obtido com SPDFA, com um máximo de 5 (CTAB 2 mM/pH 9,0). Os resultados obtidos demonstram um novo produtor de colorantes naturais, as quais têm potencial de aplicação em diversos segmentos industriais. Ademais, os resultados obtidos mostraram a eficiência das técnicas utilizadas para extração dos colorantes vermelhos, com destaque para SPDFA, que apresentou maiores valores de K. / There is worldwide interest in developing research projects involving the production and extraction of natural colorants due to serious safety problems associated with industrial use of synthetic ones. The aim of this work was to investigate the production of natural colorants from Penicillium purpurogenum DPUA 1275 by submerged culture (rotatory shaker and bioreactor) besides studying the red colorants extraction. To the production step, initial studies showed that 5 agar mycelial discs, sucrose and yeast extract as carbon and nitrogen sources, respectively, and 336 hours of bioprocess promoted the best results. To optimize the colorants production a serie of factorial designs were performed. The independent variables studied were: fermentation time, agitation speed, pH, temperature, sucrose and yeast extract concentration under the responses production of yellow, orange and red colorants. From these results, the most significant variables for the process were sucrose and yeast extract concentration. The red colorants production was optimized achieving 2.97 UA490nm, in the following conditions: 48.90 and 11.80 g/L of sucrose and yeast extract, respectively, 30 °C, 4.5 pH, 150 rev min-1 and 336 hours of culture. In the experiments performed in bioreactor, the condition that promoted the best results was 500 rpm and pH adjusted for 8.0 after 96 hours of bioprocess. Furthermore, we evaluated the red colorants stability at different conditions (pH, temperature, salts, polymers and surfactants). Concerning to pH and temperature, the red colorants were more stable under basic conditions and 70 °C; not only the salts (NaCl and Na2SO4) but also the polymers (PEG 1000, 6000 and 10000 g/mol and NaPA 8000 g/mol) and the surfactants (Tween 20, CTAB and SDS) not promoted loss of color upon the conditions evaluated. Studies of red colorants solubility and octanol water coefficient showed that these compounds exhibit a higher solubility in polar solvents and present hydrophilic characteristics. Subsequently, the extraction of red colorant was evaluated through two extraction methods: Polymeric Systems Aqueous Two Phase (ATPS) composed by PEG and NaPA and Colloidal Gas Aphrons (CGA). For the first technique, the red colorant preferentially migrated to the PEG phase. The best results were obtained with PEG 6000 g/mol in the presence of 0.1 to 0.5 M NaCl and with PEG 10000 g/mol with 0.5 M Na2SO4. To both cases the partition coefficient (K) was close to 13 and the Selectivity in terms of proteins (SeP) was close to 3. For the CGA technique, CTAB gave the best results followed by Tween 20. However, the K values were lower than the ones obtained with ATPS with a maximum of 5 in the following condition: CTAB 2 mM/pH 9.0. For the SeP, the values obtained for both techniques were close. The results above show a new producer of natural colorants which have potential application in various industries. Moreover, the results show the efficiency of the techniques used to extract the red colorants, especially to ATPS that presented higher K values.
102

Isolamento de polissacarí­deos não amiláceos da banana (musa cavendishii L. variedade Nanicão) e seu potencial uso como ingrediente funcional. / Isolation of non-starch polysaccharides from banana Cavendishii L. variety Nanicão) and its potential use as a functional ingredient.

Rayo Mendez, Lina Maria 19 July 2018 (has links)
Neste trabalho, polissacarídeos não amiláceos (PNAs) da banana madura com potencial de propriedades imunomoduladoras foram obtidos por meio da remoção dos açúcares solúveis (glicose, frutose e sacarose) do purê de banana submetido a duas técnicas de extração: sólido-líquido (ESL) com agitação mecânica e assistida por ultrassom (EAU) usando etanol a 99,5 g/100 g como solvente. Para o estudo em batelada, diferentes razões da matéria-prima/solvente (1:5, 1:7 e 1:10) g/mL, tempos de extração (30, 60 e 90) min e duas temperaturas de (25 e 65) °C foram estudados. No estudo cinético, o impacto da redução da razão matéria-prima/solvente de 1:5 para 1:3 g/mL foi estudado até 90 min, nas mesmas condições estudadas na extração em batelada. O teor de açúcares solúveis (AS) medido nos extratos foi superior na temperatura de 65°C, porém às razões de 1:7 e 1:10, não resultou em maior quantidade de AS nos extratos, portanto, menores quantidades de etanol podem ser usadas diminuindo custos. Com o emprego da técnica EAU à 25 °C e tempo de extração de 30 min, foi observado que uma redução da razão matéria-prima/solvente até 1:3 g/mL produz maior rendimento de processo. No entanto, foi observado que maiores tempos de extração promoveram degradação da parede celular da matéria-prima. Entre os modelos cinéticos testados, o ajuste do modelo de Patricelli aos dados experimentais indicou que a ESL é regida pela fase de lavagem em que ocorreu 85 % da extração dos AS. Frações molares de glicose, ácidos galacturônicos, manose, arabinose, xilose, galactose de conteúdo monossacarídeo foram observadas nos rafinados, indicando possivelmente serem parte de polissacarídeos do tipo ?-glicanos, xilomananos glucomananos, arabinogalactanos e arabinoxilanos. / In this work, non-starch polysaccharides (PNAs) of ripe bananas with potential for immunomodulatory properties were obtained by means removing the soluble sugars (glucose, fructose and sucrose) from banana puree submitted to two extraction techniques: solid-liquid (SLE) with mechanical stirring and ultrasonic assisted (UAE) using 99.5 g/ 100 g ethanol as solvent. For the batch study, different ratios of the raw material/ solvent (1:5, 1:7 and 1:10) g/ mL, extraction times of (30, 60 and 90) min and two temperatures of (25 and 65 ) °C were studied. In the kinetic study, the impact of reducing the raw material/ solvent ratio from 1:5 to 1:3 g/ mL was studied up to 90 min, under the same conditions studied in batch extraction. The soluble sugar content (AS) measured in the extracts was higher at temperature of 65 °C, however, at the ratios of 1:7 and 1:10, did not result in higher amount of AS in the extracts, therefore, smaller amounts of ethanol can be costs. With the use of the UAE technique at 25 °C and extraction time of 30 min, it was observed that a reduction of the raw material / solvent ratio up to 1:3 g / mL produces a higher process yield. However, it was observed that longer extraction times promoted degradation of the cell wall of the raw material. Among the kinetic models tested, the adjustment of Patricelli model to the experimental data indicated that the SLE the predominance is by the washing phase in which 85% of the AS extractions occurred. Glucose molar fractions, galacturonic acids, mannose, arabinose, xylose, galactose of monosaccharide content were observed in the raffinates, indicating possibly being part of polysaccharides as ?-glycan, xylomannans, glucomannans, arabinogalactans and arabinoxylans.
103

Synthèse de ligands et liquides ioniques dérivés de molécules naturelles : Application à la complexation des cations métalliques - Application à l’extraction liquide-liquide de métaux. / Synthesis of ligands and ionic liquids derived from betaine : Application to metal ions complexation - Application to metal ions liquid-liquid extraction

Messadi, Ahmed 25 October 2013 (has links)
Ces travaux abordent, d'une part l'étude de la coordination du cuivre(II) et nickel(II) avec un ligand heptadenté tripode, et d'autre part la synthèse et la caractérisation de liquides ioniques dérivés de la bétaïne.Tout d'abord, le ligand heptadenté, le tris[(L)-alanyl-2-carboxamidoéthyl]amine (H3trenala), a été synthétisé sous forme de sel de chlorure ; ses constantes de protonation ainsi que les constantes de stabilité des complexes de Cu(II) et de Ni(II) ont été déterminées par potentiométrie. Des espèces complexes mononucléaires dans lesquels le ligand est protonné ([Cu(H5trenala)]4+, [M(H4trenala)]3+), neutre ([M(H3trenala)]2+) ou déprotonné ([M(H2trenala)]+, [M(Htrenala)]) (M = Cu2+ ou Ni2+) ont été mises en évidence. Seul le Cu(II) donne des espèces dinucléaires dans lesquels le ligand est uniquement déprotonné ([Cu2(H2trenala)]2+, [Cu2(Htrenala)]2+, [Cu2(trenala)]+, [Cu2(trenala)(OH)]). A l'état solide, deux complexes dinucléaires de cuivre(II) ont pu être isolés et caractérisés (IR, UV-Vis, masse électrospray, ATG). L'étude des propriétés catalytiques de ces deux complexes montre une faible activité vis-à-vis de la réaction d'oxydation du catéchol.La seconde partie de ce travail présente la synthèse de liquides ioniques constitués par des synthons cationiques dérivés d'ester de glycine-bétaïne {trialkyl(2-éthoxy-2-oxoéthyl)ammonium (alkyl = éthyl, n-propyl et n-butyl), N-(1-méthylpyrrolidyl-2-éthoxy-2oxoéthyl)ammonium} et des anions inorganiques {bis(trifluorosulfonyl)imide (NTf2-), dicyanamide (Dca-), tétrafluoroborate (BF4-)}. Les influences de la longueur de la chaîne alkyle portée par l'atome d'azote ammonium et de la nature de l'anion associé sur les propriétés physicochimiques telles que la densité, les températures de fusion, de transition vitreuse et de décomposition, la viscosité et les fenêtres électrochimiques, ont été déterminées. De plus, des sels fondus ont pu être générés à partir de ces cations organiques associés aux anions tetrafluoroborate, dicyanamide, hexafluorophosphate (PF6-) et perchlorate (ClO4-), et leurs propriétés physicochimiques ainsi que leurs structures cristallines ont été déterminées.Ensuite, les liquides ioniques hydrophobes sont utilisés pour l'extraction des cations métalliques [Cu(II), Ni(II), Cd(II) et Pb(II)] en phase aqueuse. Cette étude montre que les rendements d'extraction d'ions métalliques, déterminés par mesure de la concentration résiduelle en métal en phase aqueuse, dépendent de la longueur de la chaîne alkyle portée par l'atome d'azote ammonium et des propriétés chélatantes de l'anion. Les rendements les plus élevés ont été obtenus avec les liquides ioniques dont l'anion possède des propriétés chélatantes. L'étude du transfert du métal montre qu'il est dépendant de l'hydrophobicité du synthon cationique. Une augmentation de l'hydrophobicité du synthon cationique conduit à une augmentation du rendement d'extraction, tout en limitant l'échange ionique et en privilégiant une extraction par paires d'ions. Enfin, l'électrodéposition en phase liquide ionique et la désextraction liquide-liquide des ions métalliques ont été étudiées. / This work deals with copper(II) and nickel(II) complexation of a polydentate tripodal ligand and with, on a second part, the synthesis and characterization of ionic liquids derived from betaine and their use in liquid-liquid extraction.On the first part, a heptadentate ligand, tris[(L)-alanyl-2-carboxamidoethyl]amine (H3trenala), has been synthesized as its tetrahydrochloride salt; its protonation constants and the stability constants of the copper(II) and nickel(II) chelates have been determined by potentiometry. Mononuclear species with protonated, neutral, or deprotonated forms of the ligand, [Cu(H5trenala)]4+, [M(H4trenala)]3+, [M(H3trenala)]2+, [M(H2trenala)]+, and [M(Htrenala)] (M=Cu2+ and Ni2+) have been detected in all cases, while only Cu2+ gives dinuclear [Cu2(H2trenala)]2+, [Cu2(Htrenala)]2+, [Cu2(trenala)]+, and [Cu2(trenala)(OH)] species. Two dinuclear copper(II) complexes have been prepared and characterized by spectroscopic techniques (IR, UV-Vis, mass electro-spray) and thermogravimetric analysis. These two dinuclear copper(II) complexes have revealed weak catalytic activity in catechol oxidation.On the second part, a series of salts based on ethyl ester betaine derivatives[trialkyl(2-ethoxy-2-oxoethyl)ammonium or N-(1-methylpyrrolidyl-2-ethoxy-2-oxoethyl)ammonium cations] with alkyl chains [ethyl, n-propyl and n-butyl] have been synthesized. These cations generate hydrophobic ionic liquids with bis(trifluoromethylsulfonyl)imide, tetrafluoroborate or dicyanamide anions. The influence of the alkyl chain length and the chemical nature of the counteranion on physicochemical properties such as density, melting point, glass transition and decomposition temperatures, viscosity, and electrochemical window have been investigated. In addition, molten salts have been generated from these organic cations with hexafluorophosphate, perchlorate, tetrafluoroborate or dicyanamide anions. Their physicochemical properties and crystal structure have been investigated.The extraction of the different metal cations (Cu2+, Ni2+, Cd2+ and Pb2+) in aqueous solution by hydrophobic ionic liquids synthesized was performed. The extraction yields, determined by the measurements of the residual metal concentration in aqueous solution, depend not only the length of the alkyl chain of the ammonium but also on the nature of the associated anion. The most promising results are obtained with ILs whose anion has a chelating ability. The mechanism of metal transfer has been studied and was related to the hydrophobicity of the cationic synthon. Increasing the hydrophobicity of the cationic synthon leads to an increase of extraction yield, thus limiting the ion exchange and promoting ion pairing extraction. Electrodeposition in ionic liquid phase and liquid-liquid desextraction of metallic ions have also been investigated.
104

Extração alcoólica de óleos de gérmen de milho e de torta de macadâmia e aproveitamento do material desengordurado na produção de concentrado proteico / Alcoholic extraction of oils from corn germ and macadamia meal and use of the defatted material in the production of protein concentrate

Sandra Lorena Blandon Navarro 19 December 2016 (has links)
No presente estudo objetivou-se avaliar o desempenho do etanol e isopropanol, absoluto e azeotrópico, na extração de óleo de macadâmia e milho. Nesse sentido, foram realizados experimentos de extração em batelada para determinar os efeitos do tipo de solvente e temperatura sobre o índice de retenção, rendimento de extração, qualidade do óleo e fração proteica. Assim, torta parcialmente desengordurada de macadâmia sem pré-tratamento prévio à etapa de extração (teor de lipídios 57,4 ± 0,7 % em base seca) foi submetida a extração, nas temperaturas de 60, 75 e 90 °C, enquanto as extrações de óleo do gérmen de milho em pellets (teor de lipídios 12,61 ± 0,05 % em base seca) foram realizadas a 50, 60, 70 e 80 °C. Os experimentos de extração em correntes cruzadas foram realizados a 70 e 75 °C para o gérmen de milho e a macadâmia, respectivamente. Os resultados mostraram que o rendimento de extração de óleo de macadâmia e milho é influenciado pelo tipo solvente, temperatura e pré-tratamento do material, sendo que com isopropanol absoluto, a 90 °C, foi possível extrair 66 % do óleo de macadâmia e a 80 °C, 87 % do óleo de milho. O índice de retenção de solução aderida as fibras (IR) foi impactado pelo tipo de solvente e características da matéria-prima, obtendo-se valores de IR maiores nas fases rafinado de macadâmia. A composição em ácidos graxos dos óleos de gérmen de milho extraídos com os solventes alcoólicos foi típica do óleo de milho, com predominância dos ácidos graxos oleico (34 %) e linoleico (48 %). As fases rafinado dos dois materiais apresentaram teor de proteínas maior que as matérias-primas iniciais, no entanto as condições do processo de extração impactaram negativamente no índice de solubilidade de nitrogênio, tornando inviável a produção de concentrado proteico de gérmen de milho. Para o óleo de milho a extração de tocoferóis e tocotrienóis foi maior com etanol, enquanto que com isopropanol conseguiu-se uma maior extração de carotenoides, o que pode ser decorrente da polaridade destes compostos bioativos. Os óleos de macadâmia extraídos com os solventes alcoólicos apresentaram maior estabilidade oxidativa (mais de 37 horas) quando comparados ao óleo bruto obtido por prensagem industrial (11,7 horas), sendo possível inferir que o uso dos solventes alcoólicos possibilita a extração de compostos que contribuem para o aumento da estabilidade do óleo. Nos experimentos em correntes cruzadas foi observado que para desengordurar a macadâmia com etanol e isopropanol absoluto são necessários mais de quatro estágios de contato, enquanto para o gérmen de milho dois estágios são suficientes. Em relação aos concentrados proteicos de macadâmia, o rendimento foi maior com os rafinados oriundos das extrações com isopropanol absoluto (13 %). Estes concentrados apresentaram boa capacidade de retenção de água e óleo (aproximadamente 2 g/g de concentrado) e estabilidade e atividade de emulsão na faixa de 56 a 59 %, desta forma pode-se sugerir que estes produtos apresentam potencial para seu aproveitamento na indústria de alimentos. A partir dos resultados pode-se inferir que a utilização dos solventes alcoólicos na extração de óleo de milho e macadâmia é tecnicamente viável, no entanto o desempenho dos solventes alcoólicos é influenciado pelas características da matéria-prima e pelo pré-tratamento do material sólido prévio à etapa de extração, obtendo-se maiores rendimentos de extração de óleo com o gérmen de milho em pellets. Também é possível inferir que os solventes em grau absoluto impactam menos na solubilidade das proteínas, permitindo a produção de concentrados proteicos de macadâmia com propriedades funcionais adequadas para seu uso na indústria de alimentos. / The objective of this study was to evaluate the performance of ethanol and isopropanol, absolute and azeotropic, in the extraction of macadamia and corn oil. Accordingly, extraction experiments were performed in batch to determine the effect of solvent type and temperature on retention index, extraction yield, quality indices of oil and protein fraction. Thus, partially defatted macadamia meal without pre-treatment prior to the extraction step (lipid content 57.4 ± 0.7 % on dry basis) was submitted to extraction at temperatures of 60, 75 and 90 °C, while oil extractions of corn germ in pellets (lipid content 12.61 ± 0.05 % on dry basis) were performed at 50, 60, 70 and 80 °C. The crosscurrent extraction experiments were performed at 70 and 75 °C for corn germ and macadamia, respectively. The results showed that the oil extraction yield of macadamia and corn is influenced by the solvent type, temperature and pre-treatment of the material, being that with absolute isopropanol at 90 °C, it was possible to extract 66 % of the macadamia oil and 87 % of the corn oil at 80 °C. The retention index of the solution adhered to the fibers (RI) was affected by the type of solvent and characteristics of the raw material, obtaining higher values of RI in the raffinate phases of macadamia. The fatty acid composition of corn germ oils extracted with alcoholic solvents was typical of corn oil, with predominance of oleic acid (34 %) and linoleic acid (48 %). The raffinate phases of the two materials showed higher protein content than the initial raw materials, however the conditions of the oil extraction process had a negative impact on the nitrogen solubility index, turning the production of protein concentrate from corn germ infeasible. For corn oil the extraction of tocopherols and tocotrienols was higher with ethanol, whereas with isopropanol a greater extraction of carotenoids was obtained, which can be due to the polarity of these bioactive compounds. Macadamia oils extracted with the alcoholic solvents showed higher oxidative stability (more than 37 hours) when compared to crude oil obtained by industrial cold pressing (11.7 hours). It is possible to infer that the use of alcoholic solvents enables to extract compounds that contribute to the increase of oil stability. In the crosscurrent extraction experiments it was observed that to produce defatted macadamia with absolute ethanol and isopropanol more than four stages of contact are required, whereas for the corn germ two stages are sufficient. Regarding protein concentrates of macadamia, the yield was higher with raffinate phases coming from the extractions with absolute isopropanol (13 %). These concentrates showed good water and oil retention capacity (approximately 2 g/g of concentrate) and emulsion stability and activity in the range of 56 to 59 %, therefore it can be suggested that these products have potential for their use in the food industry. From the results it can be inferred that the use of the alcoholic solvents in the extraction of corn and macadamia oil is technically feasible, however the performance of the alcoholic solvents is influenced by the characteristics of the raw material and by pre-treatment of the solid material prior to the extraction step, obtaining the highest oil extraction yields with the corn germ in pellets. Also, it is possible to infer that the solvents in absolute degree impact less on the solubility of the proteins, enabling the production of macadamia protein concentrates with functional properties suitable for use in the food industry.
105

Développement et caractérisation d’une cible active scintillante pour l’étude de la fission et étude des possibilités de calorimétrie de la fission avec le détecteur CARMEN / Development and characterization of an active scintillating target for fission study, and fission calorimetry study possibilities avec the CARMEN detector

Vayre, Sylvain 27 March 2015 (has links)
La désexcitation des fragments de fission reste mal comprise et les modèles théoriques ne permettent pas de prédire et d’expliquer toutes les corrélations observées dans le processus de fission. Il y a un besoin important de données simultanées sur les émissions de neutrons et de rayonnements gamma et sur l’énergie cinétique des fragments de fission. Dans ce contexte, l’utilisation d’un détecteur de fragments de fission avec le détecteur CARMEN permettrait de fournir des données contraignantes pour les modèles grâce à la mesure simultanée de la multiplicité neutronique, de l’énergie totale gamma rayonnée, de l’énergie cinétique totale des fragments et potentiellement de l’énergie totale neutron. L’objectif de ce travail de thèse a consisté à développer un détecteur de fragments de fission et à l’utiliser en association avec CARMEN pour réaliser des mesures calorimétriques de la fission. Dans un premier temps, nous avons développé un nouveau détecteur pour l’étude de la fission dont le principe est de mettre un actinide en solution dans un scintillateur organique. Des simulations Monte Carlo et différentes expériences sous faisceau de neutrons ont permis de caractériser et d’optimiser les performances de ce détecteur qui peut être utilisé comme trigger fission pour différentes mesures de sections efficaces de fission, de taux de fission spontanée ou encore comme veto fission. Dans un second temps, nous avons étudié les possibilités de mesure de l’énergie totale gamma et neutron rayonnée dans la fission avec CARMEN grâce à la caractérisation expérimentale de ses performances et à la simulation Monte Carlo et l’analyse de sa réponse « prompte » aux neutrons et aux rayonnements gamma / Still, the nuclear fission process and the de-excitation of the fission fragments is not fully understood. Current theoretical models can not predict and explain correctly every experimentally observed correlations, and new correlated data upon neutron emission, gamma-ray emission and kinetic energy of the fission fragments are needed. In this context, coincident use of a fission fragment detector and the CARMEN detector would provide compelling data for these models by measuring both neutron multiplicity, total gamma-ray energy, total kinetic energy and possibly total neutron energy. The work presented here consists in developing a fission fragment detector and using it together with CARMEN in order to perform fission calorimetry measurements. Initially, we developed a new detector for fission studies whose principle is dissolving the actinide of choice into an organic liquid scintillator. Monte Carlo simulations and neutron induced experiments were used to fully characterize its performances and shown it can be used as a fission trigger for various measurements, such as fission cross section or spontaneous fission rate measurements, and used as a fission veto. The second part of this work was dedicated to the study of CARMEN’s ability to measure the total gamma-ray energy and total neutron energy released in fission. For this purpose, lab characterization of the detector’s performances and Monte Carlo simulation and analysis of its “prompt” response to neutrons and gamma-rays were performed
106

Extração de óleo de amêndoas de baru via solventes alcoólicos: avaliação da composição do óleo, das alterações proteicas e estudo da recuperação do solvente / Extraction of baru almond oil by alcoholic solvents: evaluation of oil composition, of proteic fraction and study of recovery of solvents

Aracava, Keila Kazue 12 February 2019 (has links)
Na presente Tese de Doutorado objetivou-se avaliar a viabilidade técnica da substituição do solvente hexana, de fonte não renovável e industrialmente utilizado na extração de óleos vegetais, por solventes geralmente reconhecidos como seguros (GRAS), tais como álcoois de cadeia curta, etanol ou isopropanol, com diferentes graus de hidratação. Em adição, uma propriedade específica dos álcoois de cadeia curta foi estudada, miscibilidade parcial entre álcoois e óleo, objetivando-se a recuperação do solvente, etapa posterior ao processo de extração de óleo, denominada de dessolventização. Nesse sentido, torta de amêndoas de baru proveniente da prensagem mecânica industrial foi submetida à extração, com etanol ou isopropanol, absoluto ou azeotrópico, nas temperaturas de 60 a 90 °C, em um único estágio de contato. Os resultados mostraram que a adição de água ao solvente alcoólico impactou negativamente na eficiência de extração de óleo, enquanto o aumento da temperatura favoreceu este processo, sendo que com solvente isopropanol absoluto, a 80 °C, foi possível extrair aproximadamente 91 % do óleo disponível. Em temperaturas acima de 80 °C, os solventes utilizados, com exceção do etanol azeotrópico, apresentaram rendimentos de extração de óleo estatisticamente iguais. A composição em ácidos graxos dos óleos obtidos da extração alcoólica sequencial foi característica de óleo de amêndoas de baru, com predominância dos ácidos graxos insaturados oleico e linoleico e do saturado palmítico (aproximadamente 51, 28 e 7 %, respectivamente), independentemente da condição de processo empregada. Ainda, a extração alcoólica sequencial não influenciou nos teores dos isômeros α- e γ- tocoferol e no teor total de tocoferóis. Em relação ao estudo da fração proteica, dos sólidos desengordurados provenientes da extração alcoólica sequencial em três e dois estágios, para as temperaturas 60 e 90 °C, respectivamente, tanto a solubilidade proteica como a estabilidade térmica dos sólidos foram afetadas, sendo o índice de solubilidade de nitrogênio afetado negativamente pela hidratação do solvente alcoólico, temperatura de processo e número de estágios de contato. De uma maneira geral, a extração de óleo com solventes alcoólicos proporcionou a obtenção de um material sólido desengordurado com melhorias na capacidade de absorção de água e de óleo. Adicionalmente, verificou-se que o processo de extração alcoólica exerceu influência negativa na atividade emulsificante e positiva na capacidade de formação e estabilidade de espuma. Ademais, no estudo da recuperação do solvente, dados de equilíbrio de fases determinados para sistemas lipídicos compostos por óleo de torta de amêndoas de baru, obtido da prensagem mecânica industrial, e solventes alcoólicos, na faixa de temperatura de 15 a 60 °C, mostraram que a temperatura exerceu maior influencia na solubilidade mútua dos componentes dos sistemas com solventes absolutos em comparação aos sistemas com solventes azeotrópicos, enquanto a hidratação do solvente levou a diminuição da solubilidade, com consequente redução do coeficiente de partição do óleo. Parâmetros do modelo NRTL ajustados aos dados experimentais apresentaram adequada descrição do comportamento dos sistemas lipídicos, com desvios nas frações mássicas variando de 0,0014 a 0,0086. / The aim of this Ph.D. Thesis was to evaluate the technical feasibility of replacing the solvent hexane, from a non-renewable source and industrially used in the extraction of vegetable oils, by solvents generally recognized as safe (GRAS), such as short chain alcohols, ethanol or isopropanol, with different levels of hydration. In addition, a specific property of the short-chain alcohols, the partial miscibility between alcohols and oil, has been studied aiming at recovering the solvent after the oil extraction process, called desolventization. In this sense, baru almond cake from industrial mechanical pressing was subjected to extraction with ethanol or isopropanol, absolute or azeotropic degress, at temperatures from 60 up to 90 °C, in a single contact stage. Results showed that the addition of water to the alcoholic solvent negatively affected the oil extraction efficiency, while the increase in temperature favored this process. It was possible to extract approximately 91 % of the oil with absolute isopropanol solvent at 80 °C. At temperatures above 80 °C, the solvents, with the exception of azeotropic ethanol, showed no statistical differences regarding extraction yields. The fatty acid composition of oils obtained from sequential alcoholic extraction was characteristic of baru almond oil, with predominance of oleic and linoleic unsaturated fatty acids and palmitic saturated fatty acid (approximately 51, 28 and 7%, respectively), regardless of the condition of used. Also, the sequential alcoholic extraction did not influence the contents of the α- and γ-tocopherol isomers and the total content of tocopherols. In relation to the protein fraction study, of the defatted solids from the sequential alcoholic extraction in three and two stages, for the temperatures of 60 and 90 °C, respectively, the protein solubility and the thermal stability of the solids were affected, being the nitrogen solubility index negatively affected by the hydration of the alcoholic solvent, by the process temperature and by the number of contact stages. In general, the extraction of oil with alcoholic solvents provided a defatted solid material with improvements in water and oil absorption capacities. Additionally, it was verified that the process of alcoholic extraction exerted a negative influence on the emulsifying activity and a positive on the capacity of foam formation and stability. Moreover, in the study of solvent recovery, phase equilibrium data determined for lipid systems composed of baru almond cake oil, obtained from industrial mechanical pressing, and alcoholic solvents, in the temperature range from 15 up to 60 °C, showed that the temperature exhibited the higher influence on the mutual solubility of the components of the system with absolute solvents compared to systems with azeotropic solvents, while the hydration of the solvent led to a decrease in solubility, with consequent reduction of the partition coefficient of the oil. NRTL model parameters adjusted to the experimental data presented an adequate description of the behavior of the lipid systems, with deviations in mass fractions varying from 0.0014 to 0.0086.
107

Screening of volatile compounds in washing water and cloths from the sponge cloth process

Bergner, Sandra, Nilsson, Sandra January 2010 (has links)
<p>Freudenberg Household Products AB in Norrköping are manufacturer of sponge cloths with the well-known brand names of Wettex<sup>®</sup> and Vileda<sup>®</sup>. The production is based on the viscose fiber process and involves a high chemical demand. Recent customer complaints involve a diffuse smell from the cloths that is like a “garage odor” and occurs after a few uses. The company’s theory is that the smell derives from a chemical used in the process called Exxal 9.</p><p>The aim was to screen the washing water from two sections and the cloth before and after wash for the presence of Exxal 9 and other prominent components. The washing water samples consisted of a salt solution from one section and a water condensate from another section. A method to qualitatively and quantitatively examine the production samples was developed. To evaluate the variation over a short period of time, twelve samples were taken during four weeks. The focus for the analysis lay on production line Wx4, but comparisons with two other production lines, Wx7 and SL1, were also made. The method of choice was gas chromatography in combination with two different detectors; mass spectrometer for identification and flame ionization detector for quantification.</p><p>Exxal 9 could be identified in both of the washing water sections but in very various concentrations. At the production line Wx4, the mean concentration in the mother lye was 61.96 µl/l whereas the mean concentration in the condensate was 0.24 µl/l. The comparison between the different production lines showed significant variations, where Wx4 had the highest concentration. In the cloths, Exxal 9 could only be found before it had been washed. The concentration in the cloths was not high enough for quantification. In both the washing waters and cloths, additional unknown peaks were found. Attempts to identify all the unknowns were made but only two compounds were included in the commercial library; 2-ethyl-1-hexanol and 2-(2-butoxyethoxy)-ethanol.</p>
108

Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection

Danielsson, Conny January 2006 (has links)
Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), two groups of struc-turally related chlorinated aromatic hydrocarbons, generally referred to as “dioxins” are of great concern due to their extreme toxicity and presence in all compartments of the environment. Since they occur at very low levels, their analysis is complex and challenging, and there is a need for cost-efficient, reliable and rapid analytical alternatives to the expensive methods in-volving use of gas chromatography high-resolution mass spectrometry (GC-HRMS). It is im-portant to routinely monitor food and feed items to detect contaminations at an early stage. For the regulation of dioxins and dioxin-like PCBs in food and feed according to current legis-lation, large numbers of samples have to be analysed. Furthermore, soils at many industrial sites are also contaminated with dioxins and need remediation. In order to optimize the cost-efficiency of reclamation activities it is important to acquire information about the levels and distribution of dioxins in the contaminated areas. The aim of the studies underlying this thesis was to investigate the potential of comprehen-sive two-dimensional gas chromatography with a micro-electron capture detector (GC × GC-µECD) as a cost-effective method for analysing dioxins and dioxin-like PCBs in food, feed, fly ash and contaminated soils. Quantification studies of dioxins and dioxin-like PCBs were con-ducted and results were compared with GC-HRMS reference data. Generally, there was good agreement between both the congener-specific results and data expressed as total toxic equiva-lents (TEQs). The developed GC × GC-µECD method meets the European Community (EC) requirements for screening methods for control of dioxins and dioxin-like PCBs in food and feed. The presented results also indicate that GC × GC-µECD has potential to be used as a routine method for the congener-specific analysis of 2,3,7,8-PCDD/Fs and dioxin-like PCBs in matrices such as food and feed, fly ash and soil. However, to fully exploit the potential of the GC × GC-µECD technique, it should be combined with a fast and cost-efficient sample preparation procedure. Therefore, a number of certified reference materials (CRMs) were extracted using a new shape-selective pressurized liquid extraction technique with integrated carbon fractionation (PLE-C), and the purified extracts were analysed for PCDD/Fs using GC × GC-µECD. The results compared well with the certified values of a fly ash and a sandy soil CRM, but they were much too high for a com-plex clay soil CRM. It was concluded that this combination of techniques was very promising for screening ash and highly permeable soils. Further assessments and method revisions are still required before GC × GC-µECD can be used on a routine basis, and available software packages need to be refined in order to accelerate the data-handling procedures, which currently restrict the sample throughput.
109

Quantification of resin acids, fatty acids and sterols in process and waste water from forest industry / Kvantifiering av hartssyror, fettsyror och steroler i process och avloppsvatten från skogsindustrin

Ismailov, Taner January 2013 (has links)
This work focuses on wood extractives in effluents from the CTMP plant at Skoghall Mill. Pulp and paper industry effluents contain mostly natural compounds which are part of the trees. They are toxic to aquatic life but harmless in nature, as they are present in low concentrations. Processing tons of wood, such as in a pulp mill, strongly increases the concentrations of the toxic compounds (Ali, M. and Sreekrishnan, T., 2001) which have to be treated before transferring to the aquatic environment.Extractives can be found in different forms, as micelles soluble in water, unprocessed in fibers or absorbed on the surface of fibers. It is important to know in which forms extractives are mostly present in the effluent, so that they can be treated more efficiently. It is desired to have extractives absorbed on the fibers and fibrils present in the waste water, so they can be separated from the water and treated separately, e.g. burned for energy recovery. Dissolved extractives complicate the oxygen transfer in an aerated biological treatment step with their surface active properties (Sandberg, 2012).The aim of this study is quantification of extractives on the fibers suspended in the waste water and extractives dissolved in the water. The distribution between the two forms is an important input when designing future effluent treatment. Wood extractives itself are a wide group with different compounds. This work focuses on the main groups present in waste water: resin acids, free and esterified fatty acids and, free and esterified sterols. These groups are analyzed in different process waters and waste water before the waste water treatment plant. The measured concentrations of extractives were as expected, higher in process and effluent waters, lower in white water. Most of the extract was dissolved in the water and unfortunately fiber samples contained very low concentration from the total extract in the samples.
110

Interaction of Actinides with the Predominant Indigenous Bacteria in Äspö Aquifer - Interactions of Selected Actinides U(VI), Cm(III), Np(V) and Pu(VI) with Desulfovibrio äspöensis

Bernhard, Gert, Selenska-Pobell, Sonja, Geipel, Gerhard, Rossberg, Andre, Merroun, Mohamed, Moll, Henry, Stumpf, Thorsten 31 March 2010 (has links) (PDF)
Sulfate-reducing bacteria (SRB) frequently occur in the deep granitic rock aquifers at the Äspö Hard Rock Laboratory (Äspö HRL), Sweden. The new SRB strain Desulfovibrio äspöensis could be iso-lated. The objective of this project was to explore the basic interaction mechanisms of uranium, curium, neptunium and plutonium with cells of D. äspöensis DSM 10631T. The cells of D. äspöensis were successfully cultivated under anaerobic conditions as well in an optimized bicarbonate-buffered mineral medium as on solid medium at 22 °C. To study the interaction of D. äspöensis with the actinides, the cells were grown to the mid-exponential phase (four days). The collected biomass was usually 1.0±0.2 gdry weight/L. The purity of the used bacterial cultures was verified using microscopic techniques and by applying the Amplified Ribosomal DNA Restriction Enzyme Analysis (ARDREA). The interaction experiments with the actinides showed that the cells are able to remove all four actinides from the surrounding solution. The amount of removed actinide and the interaction mechanism varied among the different actinides. The main U(VI) removal occurred after the first 24 h. The contact time, pH and [U(VI)]initial influence the U removal efficiency. The presence of uranium caused a damaging of the cell membranes. TEM revealed an accumulation of U inside the bacterial cell. D. äspöensis are able to form U(IV). A complex interaction mechanism takes place consisting of biosorption, bioreduction and bioaccumulation. Neptunium interacts in a similar way. The experimental findings are indicating a stronger interaction with uranium compared to neptunium. The results obtained with 242Pu indicate the ability of the cells of D. äspöensis to accumulate and to reduce Pu(VI) from a solution containing Pu(VI) and Pu(IV)-polymers. In the case of curium at a much lower metal concentration of 3x10-7 M, a pure biosorption of Cm(III) on the cell envelope forming an inner-sphere surface complex most likely with organic phosphate groups was detected. To summarize, the strength of the interaction of D. äspöensis with the selected actinides at pH 5 and actinide concentrations ≥10 mg/L ([Cm] 0.07 mg/L) follows the pattern: Cm > U > Pu >> Np.

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