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Made available in DSpace on 2014-06-11T19:35:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-07-19Bitstream added on 2014-06-13T20:06:32Z : No. of bitstreams: 1 sigoli_fa_dr_araiq.pdf: 3331714 bytes, checksum: f15f140dd71661951c9acd489ff18e44 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Neste trabalho, obteve-se uma matriz porosa com alto teor de sílica a partir de vidros Pyrex® utilizando-se o tratamento hidrotérmico. A matriz porosa é formada principalmente por dois processos: (i) reação da água no estado supercrítico com a rede vítrea e, (ii) separação e lixiviação de fases. A matriz apresenta-se macroporosa, possuindo também baixa percentagem de micro e mesoporos. Através de técnicas espectroscópicas verifica-se que a matriz apresenta grupos silanóis de superfície, os quais foram utilizados em reações de funcionalização. A espectroscopia de ressonância magnética nuclear de 29Si, MAS RMN, indica a presença de grupos ordenados, (SiO)4Si, no interior da matriz e do grupo (SiO)3Si(OAl). Os espectros de 29Si, CPMAS RMN, indicam que a matriz porosa é constituída de átomos de silício localizados em dois ambientes químicos diferentes, (SiO)3Si(OH), e (SiO)4Si. Pelo espectro de 27Al MAS RMN confirma-se a presença do grupo Al-O-Si, o qual é responsável pela formação de sítios ácidos de Brönsted. Pela análise dilatométrica verifica-se que a contração máxima da matriz foi de 6% em 1365oC, aumentando a densidade do material, o tamanho médio dos poros, devido a consolidação de micro e mesoporos, diminuindo assim a área superficial. A matriz cristaliza-se em 950oC como α-cristobalita pertencente ao grupo espacial P41212. A matriz obtida foi então utilizada como suporte para complexos luminescentes. O complexo diaquatris(tenoiltrifluoroacetonato)európio(III), [Eu(tta)3(H2O)2], impregnado ou ancorado na matriz, apresenta emissões com alargamento não-homogêneo indicando que há interações entre o complexo e a superfície da matriz... / In the present work, porous silica matrix has been obtained from Pyrex glass by hydrothermal treatment under saturated steam condition. The formation process was principally investigated using scanning and transmission electron microscopies and Raman spectroscopy. The results indicate that the process of phase separation takes place on edge of vitreous sample at lower temperature than of glass-transition temperature at room atmosphere. This process occurs due to the glass hydration by hydrothermal treatment that diminishes both viscosity and glass transition temperature. The segregated orthoborate phase was leached out by water in supercritical condition. The formation and leaching of this phase together with essential reactions between water and silica at supercritical condition contribute to obtain a porous silica matrix. The matrix has a high percentage of porosity, an interconnected macroporous structure, a low percentage of micro and mesopores and also a good thermal stability. It is non-crystalline and after thermal treatment it presented X-ray pattern characteristic of cristobalite and a low contraction of volume. The chemical analysis shows a high concentration of silicon and low concentrations of aluminum and boron. The chemical environments of silicon and aluminum atoms into the porous silica matrix were investigated by solid state NMR spectroscopy. The 29Si MAS NMR spectrum exhibits a broad signal at -110 ppm, typical of an ordered silica phase. The chemical nature of surface was better understood with application of the 1H - 29Si CPMAS NMR technique. This technique leaded to a strong and selective... (Complete abstract, click electronic access below)

Resumo: Neste trabalho, obteve-se uma matriz porosa com alto teor de sílica a partir de vidros Pyrex® utilizando-se o tratamento hidrotérmico. A matriz porosa é formada principalmente por dois processos: (i) reação da água no estado supercrítico com a rede vítrea e, (ii) separação e lixiviação de fases. A matriz apresenta-se macroporosa, possuindo também baixa percentagem de micro e mesoporos. Através de técnicas espectroscópicas verifica-se que a matriz apresenta grupos silanóis de superfície, os quais foram utilizados em reações de funcionalização. A espectroscopia de ressonância magnética nuclear de 29Si, MAS RMN, indica a presença de grupos ordenados, (SiO)4Si, no interior da matriz e do grupo (SiO)3Si(OAl). Os espectros de 29Si, CPMAS RMN, indicam que a matriz porosa é constituída de átomos de silício localizados em dois ambientes químicos diferentes, (SiO)3Si(OH), e (SiO)4Si. Pelo espectro de 27Al MAS RMN confirma-se a presença do grupo Al-O-Si, o qual é responsável pela formação de sítios ácidos de Brönsted. Pela análise dilatométrica verifica-se que a contração máxima da matriz foi de 6% em 1365oC, aumentando a densidade do material, o tamanho médio dos poros, devido a consolidação de micro e mesoporos, diminuindo assim a área superficial. A matriz cristaliza-se em 950oC como α-cristobalita pertencente ao grupo espacial P41212. A matriz obtida foi então utilizada como suporte para complexos luminescentes. O complexo diaquatris(tenoiltrifluoroacetonato)európio(III), [Eu(tta)3(H2O)2], impregnado ou ancorado na matriz, apresenta emissões com alargamento não-homogêneo indicando que há interações entre o complexo e a superfície da matriz...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the present work, porous silica matrix has been obtained from Pyrex glass by hydrothermal treatment under saturated steam condition. The formation process was principally investigated using scanning and transmission electron microscopies and Raman spectroscopy. The results indicate that the process of phase separation takes place on edge of vitreous sample at lower temperature than of glass-transition temperature at room atmosphere. This process occurs due to the glass hydration by hydrothermal treatment that diminishes both viscosity and glass transition temperature. The segregated orthoborate phase was leached out by water in supercritical condition. The formation and leaching of this phase together with essential reactions between water and silica at supercritical condition contribute to obtain a porous silica matrix. The matrix has a high percentage of porosity, an interconnected macroporous structure, a low percentage of micro and mesopores and also a good thermal stability. It is non-crystalline and after thermal treatment it presented X-ray pattern characteristic of cristobalite and a low contraction of volume. The chemical analysis shows a high concentration of silicon and low concentrations of aluminum and boron. The chemical environments of silicon and aluminum atoms into the porous silica matrix were investigated by solid state NMR spectroscopy. The 29Si MAS NMR spectrum exhibits a broad signal at -110 ppm, typical of an ordered silica phase. The chemical nature of surface was better understood with application of the 1H - 29Si CPMAS NMR technique. This technique leaded to a strong and selective... (Complete abstract, click electronic access below) / Orientador: Marian Rosaly Davolos / Coorientador: Miguel Jafelicci Junior / Banca: Aldo José Gorgatti Zarbin / Banca: Hermi Felinto de Brito / Banca: Henrique Eisi Toma / Banca: Sandra Helena Pulcinelli / Doutor

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第20477号 / エネ博第346号 / 新制||エネ||69(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 坂 志朗, 教授 髙部 圭司, 准教授 河本 晴雄 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

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Doctor of Philosophy / Department of Grain Science and Industry / Yong Cheng Shi / To realize the full potential of waxy wheat flours in food applications, six advanced hard waxy wheat lines were studied. Pasting properties of waxy wheat flours as well as factors governing the pasting properties were investigated. Waxy wheat starch granules swelled more extensively and were more prone to α-amylase degradation than normal wheat starch. A combination of endogenous α-amylase activity and protein matrix contributed to a large variation of pasting properties of waxy wheat flours. Bi-axial extension properties classified dough from waxy wheat as in-elastic. Waxy wheat flour had higher water absorption and lower mixing time than normal wheat flour. Waxy wheat starch affected protein hydration but not protein extractability after optimum dough mixing. Presence of some non-protein free thiol contents and some gliadins acting as chain terminators could be the underlying reasons for waxy wheat flours producing slack dough. In an effort to improve functionality of waxy wheat flours, hydro-thermal processing was used. Two temperatures (140 and 160°C), three moisture contents (0, 12.4 and 20%), and four exposure times (0, 5, 15, 30 and 60 min) were employed. Hydrothermal processing resulted in non-cohesive waxy wheat flours with high viscosity and greater acid stability than native waxy wheat flour. A closer investigation revealed the possible role of endosperm proteins in improving pasting properties of waxy wheat flours. Upon thermal processing, waxy wheat flours demonstrated a long hydration time before forming dough. Heating decreased protein solubility while no changes in starch molecular weight distribution were observed. Our results indicate that hydro-thermal processing results in increased starch protein interaction. As part of application of waxy wheat, bread was baked by replacing normal wheat flour with two hard waxy wheat flours at 15, 30, and 45% levels. Substitution with waxy wheat flour resulted in higher loaf volume and softer loaves. However, substitution at > 30% resulted in excessive post-bake shrinkage and a ‘key-hole’ shape with an open crumb structure. Bread crumb microstructure indicated a loss of starch granule rigidity and fusing of starch granules. Soluble starch content was significantly higher in bread 1-day old crumb containing waxy wheat flour than in control bread.

Entre os processos oxidativos avançados, a fotocatálise heterogênea tem se destacado na degradação de poluentes recalcitrantes aos tratamentos convencionais. Neste processo, a geração de espécies radicalares ocorre a partir de uma fotoreação catalisada por materiais semicondutores, sendo o dióxido de titânio um dos mais utilizados, principalmente, devido a sua estabilidade química e baixo custo. A estrutura do TiO2 possui grande influência no processo fotocatalítico. Neste trabalho buscou-se preparar, a partir do TiO2 comercial e do TiO2 sintetizado pelo método sol gel, diferentes nanoestruturas do dióxido de titânio e avaliar o desempenho fotocatalítico destes materiais na degradação de fenol. Utilizando o tratamento hidrotérmico em meio fortemente alcalino, foi possível obter materiais nanoestruturados com maior área superficial, de até 308 m2 g-1. O tratamento foi aplicado em três diferentes precursores, com diferentes morfologias inicias. Avaliou-se o efeito de diferentes temperaturas (120 e 200 ºC) e tempos de tratamento (12, 24 e 48 horas), a fim de avaliar a influência das condições de tratamento e da morfologia inicial nos materiais obtidos. As amostras obtidas foram empregadas como catalisadores na degradação do poluente fenol por fotocatalise heterogênea. Em dois dos precursores estudados foram obtidas estruturas nanotubulares quando empregou-se condições mais brandas de tratamento. Em temperaturas mais severas, observou-se a formação de nanobastões. As amostras nanotubulares derivadas do TiO2 comercial anatásio, quando aplicadas na degradação do fenol, permitiram porcentagens de degradação superiores ao do precursor. Quando calcinadas, as amostras apresentaram resultados ainda melhores. O material tratado por 48 horas à 120 ºC possibilitou uma degradação de cerca de 100% do poluente, após 3 horas de irradiação. Utilizando três precursores com morfologias iniciais distintos foram observados resultados diferentes quanto a formação de nanoestruturas e atividade fotocatalítica, sendo o material obtido utilizando o TiO2 comercial anatásio, o que apresentou melhores resultados na degradação do fenol. / Among the advanced oxidation processes, heterogeneous photocatalysis has attracted great attention due the degradation of pollutants recalcitrant to conventional treatments. In this process, the generation of radical species takes place from a photoreaction catalyzed by semiconductor materials. Titanium dioxide is the most used catalyst mainly because of its chemical stability and low cost. The TiO2 structure has great influence on the photocatalytic process. In this study, different nanostructures of titanium dioxide were prepared from commercial TiO2 and TiO2 synthesized by sol gel method. The performance of these materials was evaluated the on the photocatalytic degradation of phenol. Using the hydrothermal treatment in strongly alkaline media, it was possible to obtain nanostructured materials with higher surface area, up to 308 m2 g-1. The treatment was employed in three different precursors with different initial morphology. It was evaluated the effect of different temperatures (120 and 200 °C) and treatment times (12, 24 and 48 hours) to assess the influence of processing conditions and of the initial morphology. The different materials were employed as catalysts in the phenol degradation by heterogeneous photocatalysis. In two precursors studied, nanotubular structures were obtained when it was used milder conditions of treatment. In more severe temperatures, it was observed nanorods formation. Nanotubular samples were obtained from commercial TiO2 anatase. When applied to the degradation of phenol, this material allowed degradation percentages higher than the precursor. When calcined, these samples showed even better results. The material treated for 48 hours at 120 °C allowed a phenol degradation of almost 100% after 3 hours of irradiation. Using three precursors with different initial morphologies it was observed different results regarding the formation of nanostructures and photocatalytic activity. The material obtained from the commercial anatase TiO2 it was the sample which presented the best result in the degradation of phenol

TiO2 in anatase form is the most widely studied material for photocatalytic reactions. Utilization of oxide support materials such as silica with suitable transparency within band gap range of TiO2 is promising technique to obtain efficient photocatalysts for many applications. In the present study, simultaneous co-hydrolyzation of tetraethyl orthosilacate (TEOS) and titanium tetrabutaoxide (TBOT) precursors were carried out in the presence of hydrochloric acid. The effects of washing with low vapor pressure solvent(n-octane), drying conditions, hydrothermal ageing and TiO2/SiO2 ratio on the catalyst structure and photocatalytic activity were studied. The samples were characterized by XRD, BET, DRIFTS techniques and the activity was measured for liquid phase room temperature oxy/demineralization of phenol under artificial solar irradiation. The reaction intermediates were followed by UV/vis spectrophotometer and HPLC. It was found that the hydrothermal treatment contributes better degree of crystalinity, higher surface area and thus photocatalytic activity compared to the samples which were synthesized with conventional drying at 100oC overnight. The formation of Ti-O-Si interface indicating the degree of dispersion was evidenced by DRIFTS technique for all hydrothermally tretated samples. The highest surface area and photocatlytic activity was observed with hydrothermally treated catalyst with TiO2/SiO2:0.34 composition.

Whole grain is associated with rougher texture and off-flavours which has decreased consumer acceptance. Pasta drying is also critical during production because of influence on texture and quality. The effects of drying type and whole grain content on physicochemical and qualitative properties of pasta were investigated. Increasing whole grain content lowered paste viscosity and increased cooking loss while low temperature drying improved quality. The impact of these effects on pasta texture and flavour was further explored. While bitterness, branniness, and surface roughness positively correlated with whole grain content, drying type only affected firmness. Phenolic content, headspace, and textural analysis corroborated this data. Change in pasta flavour upon addition of sodium-reduced cheese sauce was also examined. Sodium not only enhances flavour of dishes, it also suppresses bitterness. While flavours were uniquely affected upon sauce addition, sodium content did not affect bitterness. Headspace analysis using SIFT-MS showed volatile concentration to reduce, likely caused by a barrier created from the sauce. / MITACS Accelerate, Kraft Mississauga Mill