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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.
11

Avaliação in vitro do ascorbato de sódio em diferentes tempos de aplicação e concentrações na resistência de união à dentina tratada com hipoclorito de sódio e/ou EDTA / In vitro assessment of different times and concentrations of sodium ascorbate on the bond strength to dentin treated with sodium hypochlorite and/or EDTA

Lacerda, Aniele Carvalho, 1983- 02 July 2013 (has links)
Orientador: Caio Cezar Randi Ferraz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-22T00:09:37Z (GMT). No. of bitstreams: 1 Lacerda_AnieleCarvalho_M.pdf: 1787368 bytes, checksum: 7ae8501ef4c6b79a8032427d280dbdf0 (MD5) Previous issue date: 2013 / Resumo: O objetivo deste estudo foi avaliar in vitro o ascorbato de sódio em diferentes tempos de aplicação e concentrações na resistência de união de um sistema adesivo convencional de 3 passos à dentina da câmara pulpar tratada com hipoclorito de sódio, EDTA ou suas associações. Oitenta e quatro incisivos bovinos hígidos e recém-extraídos foram seccionados, obtendo-se amostra do terço médio vestibular da coroa. As amostras foram distribuídas, aleatoriamente, em 14 grupos (n=6) de acordo com o tratamento superficial da dentina com substâncias químicas. G1(controle): NaCl 0,9%; G2: NaOCl 5,25%; G3 e G4: NaOCl 5,25% seguido de ascorbato de sódio 10 ou 20%, respectivamente, por 10 minutos; G5: NaCl 0,9% seguido de EDTA 17%; G6 e G7: NaCl 0,9% + EDTA 17% seguido de ascorbato de sódio 10 ou 20%, respectivamente, por 10 minutos; G8: NaOCl 5,25% + EDTA 17% + NaOCl 5,25%; G9, G10 e G11 semelhantes ao G8 seguido de ascorbato de sódio 10% por 1, 5 ou 10 minutos, respectivamente; G12, G13 e G14 semelhantes ao G8 seguido de ascorbato de sódio 20% por 1, 5 ou 10 minutos, respectivamente. Ao final, todas as amostras foram imersas em NaCl 0,9% por 3 minutos. A dentina foi hibridizada com Adper Scotchbond Multi-Purpose e, em seguida, preparada para o teste de resistência à microtração. Os dados obtidos foram analisados estatisticamente (? = 0.05) e os padrões de fratura determinados em Microscopia Eletrônica de Varredura (MEV). Os valores de resistência de união do Grupo 1 foram estatisticamente maiores do que os dos demais grupos experimentais, exceto Grupo 4. O Grupo 4 apresentou média superior aos Grupos 9 e 14 (p<0.05). No entanto, não foram verificadas diferenças estatísticas entre os demais grupos, independente do protocolo de tratamento das superfícies dentinárias, tempo de aplicação e concentração do ascorbato de sódio. Concluiu-se que o NaOCl e o EDTA, sozinhos ou associados, reduziram significativamente (p<0.05) os valores de resistência de união na interface resina-dentina da câmara pulpar. O ascorbato de sódio restabeleceu os valores de adesão da dentina da câmara pulpar apenas quando utilizado na concentração de 20% por 10 minutos após o uso isolado de NaOCl (Grupo 4) / Abstract: The aim of this study was to evaluate in vitro the sodium ascorbate in different application times and concentrations on bond strength of a conventional 3 steps adhesive system to the pulp chamber dentin treated with sodium hypochlorite, EDTA or their associations. Eighty-four intact bovine incisors, freshly extracted, were sectioned in order to obtain samples of the buccal middle third of the crown. The samples were randomly distributed into 14 groups (n = 6) according to the chemical surface treatment of the dentin. G1 (control): 0.9% NaCl; G2: 5.25% NaOCl, G3 and G4: 5.25% NaOCl followed by 10 or 20% sodium ascorbate, respectively, for 10 minutes; G5: 0.9% NaCl followed by 17% EDTA; G6 and G7: 0.9% NaCl + 17% EDTA followed by 10 or 20% sodium ascorbate respectively, for 10 minutes; G8: 5.25% NaOCl + 17% EDTA + 5.25% NaOCl; G9, G10 and G11: similar to G8 followed by 10% sodium ascorbate for 1, 5 or 10 minutes, respectively; G12, G13 and G14: similar to G8 followed by 20% sodium ascorbate for 1, 5 or 10 minutes, respectively. At the end, all samples were immersed in 0.9% NaCl for 3 minutes. The dentin was hybridized with Adper Scotchbond Multi-Purpose and then prepared for the microtensile bond strength test. Data were analyzed statistically (?= 0.05) and the failure mode classified under Scanning Electron Microscopy (SEM). The values of bond strength of Group 1 were significantly higher than other groups, except for Group 4. Group 4 showed average superior to Groups 9 and 14 (p <0.05). However, no differences were observed among the other groups, regardless of the dentin surface treatment, application time or concentration of sodium ascorbate. It was concluded that NaOCl and EDTA, whether associated or not, significantly reduced (p <0.05) the bond strength values of resin-dentin interface in the pulp chamber. Sodium ascorbate restored the bond strength values of pulp chamber dentin only when used at a concentration of 20% for 10 minutes after an isolated application of NaOCl on dentin (Group 4) / Mestrado / Endodontia / Mestra em Clínica Odontológica
12

Effects of drag reducing agents on pressure drop and flow characteristics in multiphase inclined pipelines

Daas, Mutaz A. January 2000 (has links)
No description available.
13

A study of drag reducing agents in multiphase flow in large diameter horizontal pipelines

Tullius, Lisa January 2000 (has links)
No description available.
14

Effect of a drag reducing agent on pressure drop and flow regime transitions in multiphase horizontal low pressure pipelines

Vancko, Jr., Robert M. January 1997 (has links)
No description available.
15

Metalofármacos de dirutênio(II,III): síntese, caracterização e interações com biomoléculas e ciclodextrina / Diruthenium(II,III) metallodrugs: synthesis, characterization and interactions with biomolecules and cyclodextrin

Santos, Rodrigo Luis da Silva Ribeiro dos 04 April 2012 (has links)
Os compostos de coordenação de rutênio têm recebido grande atenção para tratamento do câncer. Em particular, estudos do grupo mostraram que um metalofármaco de dirutênio(II,III) com o fármaco anti-inflamatório não-esteróide ibuprofeno apresenta boa atividade para tumor cerebral maligno. Neste contexto, o presente trabalho teve como objetivo ampliar os estudos com a obtenção de novos complexos, investigar as interações dos metalofármacos com moléculas de interesse biológico e preparar materiais híbridos destes com ciclodextrina. Desenvolveu-se metodologia sintética para a preparação de dois novos metalofármacos de dirutênio(II,III) de fórmula geral [Ru2(O2CR)4Cl], em que O2CR = cetoprofenato (cet) ou fenbufenato, a partir do precursor [Ru2(O2CH3)4Cl]. Os novos complexos foram caracterizados principalmente por meio de técnicas espectroscópicas, difratometria de raios x e análise térmica. Estudos de reatividade foram realizados para a espécie [Ru2(O2CH3)4(H2O)2]+, obtida a partir do precursor [Ru2(O2CH3)4Cl] em solução aquosa. Constantes de equilíbrio e parâmetros termodinâmicos para as reações de substituição axial água-cloreto, e também parâmetros cinéticos das reações deste complexo com os aminoácidos glicina, triptofano, cisteína e histidina, e com os agentes redutores glutationa e ácido ascórbico, foram determinados. Estudos sobre as interações com a proteína albumina do soro humano (HSA) foram efetuados para os complexos [Ru2(O2CH3)4Cl] e [Ru2(cet)4Cl], e também para o derivado análogo de ibuprofenato (ibp), [Ru2(ibp)4Cl]. Novos materiais híbridos contendo os complexos [Ru2(O2CR)4Cl] (O2CR = ibuprofenato ou cetoprofenato) e hidroxipropil-&#946;-ciclodextrina foram obtidos, usando-se a técnica de spray-drying, e caracterizados. / Ruthenium compounds have received great attention for cancer therapy. In particular, studies from our research group have found that a metallodrug of diruthenium(II,III) with the non-steroidal anti-inflammatory drug ibuprofen, has good activity for malignant brain tumor. In this context, the main purposes of this work were to improve these studies, to investigate some interactions of these metallodrugs with biologically relevant molecules, and also to prepare hybrid materials of these complexes with cyclodextrin. Synthetic methodologies were developed to prepare two novel diruthenium(II,III) metallodrugs, with the general formula [Ru2(O2CR)4Cl], where O2CR = ketoprofen (ket) or fenbufen starting from the precursor [Ru2(O2CH3)4Cl]. The novel complexes were characterized mainly by spectroscopical techniques, X-rays difractometry and termal analysis. Reactivity studies were performed for the species [Ru2(O2CH3)4(H2O)2]+ obtained from the precursor [Ru2(O2CH3)4Cl] in aqueous solution. Equilibrium constants and thermodynamic parameters for water-chloride axial substitutions, and also kinetic parameters for the reactions of this complex with the amino acids glycine, tryptophan, cysteine and histidine, and the reducing agents glutathione and ascorbic acid, were determined. Studies on the interactions with the human serum albumin (HSA) protein were performed for the complexes [Ru2(O2CH3)4Cl] and [Ru2(ket)4Cl], and also for the analogue derivative of the ibuprofen drug (ibp), [Ru2(ibp)4Cl]. Novel hybrid materials containing complexes [Ru2(O2CR)4Cl] (O2CR = ibuprofenato or ketoprofenato) and &#946;-hydroxypropyl-cyclodextrin were prepared by using spray-drying technique and characterized.
16

Biochemical conversion of biomass to biofuels : pretreatment–detoxification–hydrolysis–fermentation

Soudham, Venkata Prabhakar January 2015 (has links)
The use of lignocellulosic materials to replace fossil resources for the industrial production of fuels, chemicals, and materials is increasing. The carbohydrate composition of lignocellulose (i.e. cellulose and hemicellulose) is an abundant source of sugars. However, due to the feedstock recalcitrance, rigid and compact structure of plant cell walls, access to polysaccharides is hindered and release of fermentable sugars has become a bottle-neck. Thus, to overcome the recalcitrant barriers, thermochemical pretreatment with an acid catalyst is usually employed for the physical or chemical disruption of plant cell wall. After pretreatment, enzymatic hydrolysis is the preferred option to produce sugars that can be further converted into liquid fuels (e.g. ethanol) via fermentation by microbial biocatalysts. However, during acid pretreatment, several inhibitory compounds namely furfural, 5-hydroxymethyl furfural, phenols, and aliphatic acids are released from the lignocellulose components. The presence of these compounds can greatly effect both enzymatic hydrolysis and microbial fermentation. For instance, when Avicel cellulose and acid treated spruce wood hydrolysate were mixed, 63% decrease in the enzymatic hydrolysis efficiency was observed compared to when Avicel was hydrolyzed in aqueous citrate buffer. In addition, the acid hydrolysates were essentially non-fermentable. Therefore, the associated problems of lignocellulose conversion can be addressed either by using feedstocks that are less recalcitrant or by developing efficient pretreatment techniques that do not cause formation of inhibitory byproducts and simultaneously give high sugar yields. A variety of lignocellulose materials including woody substrates (spruce, pine, and birch), agricultural residues (sugarcane bagasse and reed canary grass), bark (pine bark), and transgenic aspens were evaluated for their saccharification potential. Apparently, woody substrates were more recalcitrant than the rest of the species and bark was essentially amorphous. However, the saccharification efficiency of these substrates varied based on the pretreatment method used. For instance, untreated reed canary grass was more recalcitrant than woody materials whereas the acid treated reed canary grass gave a higher sugar yield (64%) than the woody substrates (max 34%). Genetic modification of plants was beneficial, since under similar pretreatment and enzymatic hydrolysis conditions, up to 28% higher sugar production was achieved from the transgenic plants compare to the wild type. As an alternative to the commonly used acid catalysed pretreatments (prior to enzymatic hydrolysis) lignocellulose materials were treated with four ionic liquid solvents (ILs): two switchable ILs (SILs) -SO2DBUMEASIL and CO2DBUMEASIL, and two other ILs [Amim][HCO2] and [AMMorp][OAc]. viii After enzymatic hydrolysis of IL treated substrates, a maximum amount of glucan to glucose conversion of between 75% and 97% and a maximum total sugar yields of between 71% and 94% were obtained. When using acid pretreatment these values varied between 13-77% for glucan to glucose conversion and 26-83% for total sugar yield. For woody substrates, the hemicellulose recovery (max 92%) was higher for the IL treated substrates than compared to acid treated samples. However, in case of reed canary grass and pine bark the hemicellulose recovery (90% and 88%, respectively) was significantly higher for the acid treated substrates than the IL treated samples. To overcome the inhibitory problems associated with the lignocellulose hydrolysates, three chemical conditioning methods were used 1. detoxification with ferrous sulfate (FeSO4) and hydrogen peroxide (H2O2) 2. application of reducing agents (sulfite, dithionite, or dithiothreitol) and 3. treatment with alkali: Ca(OH)2, NaOH, and NH4OH. The concentrations of inhibitory compounds were significantly lower after treatments with FeSO4 and H2O2 or alkali. Using reducing agents did not cause any decrease in the concentration of inhibitors, but detoxification of spruce acid hydrolysates resulted in up to 54% improvement of the hydrolysis efficiency (in terms of sugar release) compared to untreated samples. On the other hand, application of detoxification procedures to the aqueous buffer resulted in up to 39% decrease in hydrolysis efficiency, thus confirming that the positive effect of detoxification was due to the chemical alteration of inhibitory compounds. In addition, the fermentability of detoxified hydrolysates were investigated using the yeast Saccharomyces cerevisiae. The detoxified hydrolysates were readily fermented to ethanol yielding a maximum ethanol concentration of 8.3 g/l while the undetoxified hydrolysates were basically non-fermentable.
17

Metalofármacos de dirutênio(II,III): síntese, caracterização e interações com biomoléculas e ciclodextrina / Diruthenium(II,III) metallodrugs: synthesis, characterization and interactions with biomolecules and cyclodextrin

Rodrigo Luis da Silva Ribeiro dos Santos 04 April 2012 (has links)
Os compostos de coordenação de rutênio têm recebido grande atenção para tratamento do câncer. Em particular, estudos do grupo mostraram que um metalofármaco de dirutênio(II,III) com o fármaco anti-inflamatório não-esteróide ibuprofeno apresenta boa atividade para tumor cerebral maligno. Neste contexto, o presente trabalho teve como objetivo ampliar os estudos com a obtenção de novos complexos, investigar as interações dos metalofármacos com moléculas de interesse biológico e preparar materiais híbridos destes com ciclodextrina. Desenvolveu-se metodologia sintética para a preparação de dois novos metalofármacos de dirutênio(II,III) de fórmula geral [Ru2(O2CR)4Cl], em que O2CR = cetoprofenato (cet) ou fenbufenato, a partir do precursor [Ru2(O2CH3)4Cl]. Os novos complexos foram caracterizados principalmente por meio de técnicas espectroscópicas, difratometria de raios x e análise térmica. Estudos de reatividade foram realizados para a espécie [Ru2(O2CH3)4(H2O)2]+, obtida a partir do precursor [Ru2(O2CH3)4Cl] em solução aquosa. Constantes de equilíbrio e parâmetros termodinâmicos para as reações de substituição axial água-cloreto, e também parâmetros cinéticos das reações deste complexo com os aminoácidos glicina, triptofano, cisteína e histidina, e com os agentes redutores glutationa e ácido ascórbico, foram determinados. Estudos sobre as interações com a proteína albumina do soro humano (HSA) foram efetuados para os complexos [Ru2(O2CH3)4Cl] e [Ru2(cet)4Cl], e também para o derivado análogo de ibuprofenato (ibp), [Ru2(ibp)4Cl]. Novos materiais híbridos contendo os complexos [Ru2(O2CR)4Cl] (O2CR = ibuprofenato ou cetoprofenato) e hidroxipropil-&#946;-ciclodextrina foram obtidos, usando-se a técnica de spray-drying, e caracterizados. / Ruthenium compounds have received great attention for cancer therapy. In particular, studies from our research group have found that a metallodrug of diruthenium(II,III) with the non-steroidal anti-inflammatory drug ibuprofen, has good activity for malignant brain tumor. In this context, the main purposes of this work were to improve these studies, to investigate some interactions of these metallodrugs with biologically relevant molecules, and also to prepare hybrid materials of these complexes with cyclodextrin. Synthetic methodologies were developed to prepare two novel diruthenium(II,III) metallodrugs, with the general formula [Ru2(O2CR)4Cl], where O2CR = ketoprofen (ket) or fenbufen starting from the precursor [Ru2(O2CH3)4Cl]. The novel complexes were characterized mainly by spectroscopical techniques, X-rays difractometry and termal analysis. Reactivity studies were performed for the species [Ru2(O2CH3)4(H2O)2]+ obtained from the precursor [Ru2(O2CH3)4Cl] in aqueous solution. Equilibrium constants and thermodynamic parameters for water-chloride axial substitutions, and also kinetic parameters for the reactions of this complex with the amino acids glycine, tryptophan, cysteine and histidine, and the reducing agents glutathione and ascorbic acid, were determined. Studies on the interactions with the human serum albumin (HSA) protein were performed for the complexes [Ru2(O2CH3)4Cl] and [Ru2(ket)4Cl], and also for the analogue derivative of the ibuprofen drug (ibp), [Ru2(ibp)4Cl]. Novel hybrid materials containing complexes [Ru2(O2CR)4Cl] (O2CR = ibuprofenato or ketoprofenato) and &#946;-hydroxypropyl-cyclodextrin were prepared by using spray-drying technique and characterized.
18

Efeito da enzima transglutaminase na digestabilidade e antigenicidade da ß-Lactoglobulina / Effect of the transglutaminase enzyme in the digestability and antigenicity of the ß-lactoglobulin

Vuolo, Milena Morandi, 1984- 02 February 2012 (has links)
Orientador: Flavia Maria Netto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-19T11:45:02Z (GMT). No. of bitstreams: 1 Vuolo_MilenaMorandi_M.pdf: 1172548 bytes, checksum: 0065404d0770c2d788c07526e0f82ae8 (MD5) Previous issue date: 2012 / Resumo: O leite bovino contém proteínas que são consideradas antigênicas e capazes de induzir algum tipo de resposta imunológica, dentre elas destaca-se a ß-lactoglobulina (ß-Lg). A utilização da enzima transglutaminase (TG), que catalisa reações de ligação e-(?-glutamina)lisil inter ou intramoleculares, incorporação de aminas e desaminação tem demonstrado eficiência em alterar o potencial antigênico de alimentos. O presente trabalho teve como objetivo estudar o efeito da reação de polimerização induzida pela TG na atividade antigênica da ß-Lg e sua digestibilidade, na presença dos agentes redutores glutationa (GSH) e ácido ascórbico (AA). As modificações da ß-Lg com a TG na presença dos agentes redutores foram realizadas através de experimentos fatoriais 22 nos quais as variáveis independentes foram a relação enzima:substrato (E/S) (0 ¿ 51,6 U TG g -1 de proteína) e concentração dos agentes redutores, [GSH] (0 - 0,67 mmol/L) ou [AA] (0- 0,02 mol/L) e as variáveis dependentes foram grau de polimerização e concentração de IgE. A polimerização foi avaliada por eletroforese em gel de poliacrilamida (SDS-PAGE), e grau de polimerização (GP) através da determinação de lisinas livres. A avaliação da antigenicidade foi feita por ELISA, utilizando soro de camundongos BALB/c sensibilizados com ß-Lg na forma nativa. A resistência das amostras à ação da pepsina foi avaliada por eletroforese em gel de poliacrilamida na presença de SDS e tricina (SDSPAGE/Tricina). Os tratamentos realizados com TG e GSH apresentaram polímeros de alta massa molar (MM > 97,4 kDa), exceto para a condição do ensaio 5 (0,34 mmol/L GSH), que não utilizou TG. Os tratamentos com TG e AA também apresentaram polímeros de alta massa molar (MM > 97,4 kDa), exceto para a condição do ensaio 2 (44,1 U de TG g -1 e 0,003 mol/L de AA) e ensaio 5 (0,01 mol/L AA, que não utilizou TG). O GP foi maior para as amostras tratadas com TG na presença de agentes redutores, quando comparadas às amostras tratadas somente com TG ou agente redutor. Os resultados mostraram que a presença dos agentes redutores levou ao aumento da polimerização pela TG ao desnaturar a proteína levando à maior exposição dos aminoácidos lisina e glutamina. Não houve diminuição na antigenicidade da ß-Lg tratada com TG na presença de GSH ou AA, porém houve aumento da antigenicidade de algumas amostras obtidas sob algumas das condições dos ensaios realizados com os agentes redutores quando comparadas à ß-Lg. Os tratamentos realizados com TG na presença dos agentes redutores não aumentaram a digestibilidade da ß-Lg pela pepsina. Os digeridos das amostras obtidas sob as condições relativas aos níveis extremos do planejamento experimental (±1,41) e o ponto central, foram avaliados quanto à sua antigenicidade. Os resultados mostraram que não houve diminuição da antigenicidade da ß-Lg tratada com TG e GSH ou TG e AA., quando comparadas à ß-Lg. A polimerização com TG na presença de agentes redutores GSH e AA não foi capaz de modificar a antigenicidade das amostras digeridas, sugerindo que não houve modificações na proteína capazes de aumentar sua digestibilidade pela pepsina ou modificar regiões de epítopos / Abstract: Cow¿s milk contains proteins which are considered antigenic and able to lead to immune response, among them ß-lactoglobulin (ß-Lg) is the most important. The transglutaminase (TG) is the only enzyme commercially used that catalyses inter or intramolecular cross linking reaction in various proteins and demonstrates efficiency to alter the antigenic potential of food. The current work aimed at studying the effect of the reaction of induced polymerization by TG in presence of the reducing agents glutathione (GSH) as well as ascorbic acid (AA) in the antigenic activity of ß-Lg and its digestibility. The modifications in ß-Lg induced by TG in presence of reducing agents were carried out using factorial experiments 22, in which the independent variables were the enzyme:substrate ratio (E/S) (0 ¿ 51,6 U TG g -1) and concentration of reducing agents, [GSH] (0 - 0,67 mmol/L) or [AA] (0- 0,02 mol/L), and the dependent variables were the polymerization degree and concentration of IgE. Polymerization was assessed by electrophoresis in polyacrylamide gel (SDSPAGE), and the polymerization degree (PD) was determined by the free lysine content. The assessment of antigenicity was by ELISA assay, using serum of BALB/c mice sensitized with native ß-Lg. The resistance of the samples to the action of pepsin was evaluated by electrophoresis in polyacrylamide gel in presence of SDS and tricine (SDSPAGE/Tricine). The treatments using TG and GSH showed high molecular weight polymers (MM > 97,4kDa), except for a test condition 5 (0,34 mmol/L GSH), where TG was not used. The treatments with TG and AA also showed polymers of high molecular weight (MM > 97,4kDa), except for the test condition 2 (44,1 U TG g -1 and 0,003 mol/L of AA) and test 5 (0,01 mol/L AA, without TG). The PD was higher in the samples treated with TG in presence of reducing agents, when compared to samples treated only with TG or reducing agents. The results showed that the presence of reducing agents led to the increase of polymerization by TG since they denature the protein, leading to increased exposure of the amino acids glutamine and lysine, substrate for TG. The results showed that there was no reduction in the antigenicity of ß-Lg treated with TG in presence of GSH or AA, however an increase in the antigenicity of some modified samples was observed when compared to the native ß-Lg. . The treatments carried out with TG and reducing agents did not increase the digestibility of the ß-Lg by pepsin. The antigenicity of the digested from the samples obtained under the conditions of the extreme levels of experimental planning (±1,41) and at the central point were assessed. The results showed that after digestion with pepsin there was no decrease of the antigenicity of ß-Lg treated with TG in the presence of GSH or AA as compared to digested ß-Lg. Polymerization with TG in the presence of reducing agents was not able to alter the antigenicity of the samples, which suggests that there were no modifications in the protein that would be able to increase its digestibility by pepsin as well as the epitopes regions of the ß-Lg / Mestrado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Mestre em Alimentos e Nutrição
19

Síntese e estabilização de nanopartículas de ouro para fins biotecnológicos e cosméticos / Synthesis and stabilization of gold nanoparticles for biotechnological and cosmetics uses

SILVA, ANDRESSA A. da 25 May 2017 (has links)
Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2017-05-25T13:39:09Z No. of bitstreams: 0 / Made available in DSpace on 2017-05-25T13:39:09Z (GMT). No. of bitstreams: 0 / As sínteses de nanopartículas de ouro (AuNPs) com os agentes redutores e estabilizantes citrato de sódio e goma arábica bem como sua caracterização foram estudadas neste trabalho. As sínteses foram realizadas por meio de aquecimento e uso de radiação gama em fonte de 60Co nas doses 1, 7,5 e 15 kGy. Neste contexto, foram estudadas as propriedades e a estabilidade das AuNPs formadas por meio de técnicas de caracterização tais como espectroscopia de absorção UV-Vis, verificando as bandas características das AuNPs assim como a estabilidade física das mesmas. As amostras sintetizadas com citrato de sódio (AuCit) apresentaram comprimentos de onda que variaram entre 520 e 525 nm e as amostras sintetizadas com goma arábica (AuGA) apresentaram comprimentos de onda entre 530 e 540 nm. A análise de espalhamento de luz dinâmica, do inglês \"Dynamic Light Scattering\" (DLS) foi utilizada para determinar o tamanho hidrodinâmico das nanopartículas formadas no período de três meses, demonstrando que as amostras AuCit apresentaram tamanhos hidrodinâmicos médios que variaram de 20 a 50 nm enquanto que as amostras AuGA sintetizadas por aquecimento e com uso de radiação gama apresentaram tamanhos hidrodinâmicos médios que variaram de 50 a 115 nm. As análises de microscopia eletrônica de varredura com emissão de campo (MEV-FEG) e microscopia eletrônica de transmissão (MET) foram utilizadas para determinar a distribuição real de tamanhos das nanopartículas e sua forma geométrica. Nesta caracterização as AuGA apresentaram diâmetros menores do que os analisados por DLS, sugerindo assim possível encapsulamento das AuNPs. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
20

Evaluation of Alumina Nanofluids and Surfactant Drag Reducing Solutions to Improve Heat Transfer for Aircraft Cooling Systems

Narvaez, Javier Artemio January 2018 (has links)
No description available.

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