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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.
31

Fracionamento e caracterização quimica da parede celular de levedura : propriedades funcionais e fisiologicas das frações / Fracionamento and quimica characterization of the cellular wall of leavening - functional and physiological properties of the fractions

Chaud, Saula Goulart 08 September 2004 (has links)
Orientador : Valdemiro Carlos Sgarbieri / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-09-27T19:15:11Z (GMT). No. of bitstreams: 1 Chaud_SaulaGoulart_D.pdf: 1321140 bytes, checksum: ab67e4743a9713d2e1ac51a83eb769d1 (MD5) Previous issue date: 2004 / Resumo: O presente trabalho teve por objetivo o fracionamento e a caracterização química da parede celular (PC) de levedura obtida como subproduto do processo industrial da produção de etanol, visando avaliar as propriedades funcionais e fisiológicas do material fracionado. A PC foi fracionada em glicoproteína (GP), glicana mais manana (G+M), glicana insolúvel (GI), glicana solúvel (GS) e manana (M) que foram caracterizadas quanto à composição centesimal, perfil de aminoácidos, minerais, ácidos graxos e quantificação de monossacarídeos. A proporção entre os componentes da PC foi, fibra (77,8%), com predominância (74%) de fibra solúvel, permanecendo no material 18 a 20% de proteína. O teor de açúcares totais da PC foi 80,8 g/100g e o teor de lipídios foi de 2,00%. Dentre os ácidos graxos saturados predominaram palmítico e esteárico, monoinsaturados palmitoléico e oléico, poliinsaturados linoléico e a¿ linolénico. Os principais elementos minerais foram cálcio, fósforo, potássio e ferro, sendo que a PC representa uma excelente fonte de ferro e cobre. As frações obtidas da PC foram M, 25,13% e GI, 42,92% p/p. As frações com maior conteúdo de fibra foram M, 70,34% de fibra solúvel, GI, 75,20% de fibra insolúvel, G+M, 60,23% fibra solúvel e GS, 70,73% fibra solúvel. Teores de açúcares redutores, M, 70%, com 48,4% de manose, GI, 28,95% e GS, 25,07% glicose. A fração G+M continha 28,08 g/100g de carboidratos totais e 20,0% de redutores totais. A GS apresentou a maior solubilidade, a G+M a menor solubilidade do N e de sólidos totais e a GI apresentou o menor índice de solubilidade. A GS apresentou a maior capacidade de retenção de água (14,36 g/g de amostra) e o menor índice (0,06%) de solubilidade em água. A fração GP reteve (5,33 g/g de amostra) e 83,83% de solubilidade. A viscosidade (95oC) e a viscosidade final (50oC) obedeceram à seguinte ordem: GS > GI > G+M > M > GP e PC. A GI (12% e 14% p/v) apresentou o maior índice de dureza de gel. As frações GP e M apresentaram as melhores propriedades emuslificantes que melhoraram significativamente com a adição de 0,2 , 0,4 e 0,6% (p/v) de ovoalbumina nas suspensões a 1% do material em estudo. Avaliou-se os efeitos da substituição da fibra de uma dieta padrão (AIN-P) por 10% de fibra de cada uma das frações da PC, formulando-se as dietas G+M, M, GI, GS. Ao final de 28 dias, os animais em dieta G+M ganharam menos peso que nas demais. As dietas AIN-M (padrão modificada com 10% celulose) e M foram as que proporcionaram um maior ganho de peso, seguidas das dietas padrão (AIN-P) e GI. O QEA da dieta G+M foi o menor ao longo dos 28 dias. Os maiores índices de digestibilidade da proteína foram observados nas dietas AIN-M, AIN-P e M. Com exceção da dieta G+M observou-se efeitos hipocolesterolêmico e hipolipidêmico em todas as dietas, porém, efeito hiperglicêmico em relação ao valor inicial (T0). Não houve modificações significativas na microflora intestinal dos animais em nenhuma das dietas. As quantidades de lipídios totais e colesterol excretados (fezes) variaram bastante, sendo que a dieta M apresentou maior especificidade para excreção do colesterol. Dentre os AGV, o ácido acético foi o predominante, seguido do propiônico e do butírico, em todas as dietas estudadas. As concentrações de ácido butírico nas dietas contendo M, G+M e G foram significativamente superiores aos padrões (AIN-P e AIN-M) / Abstract: The objectives of this work were the fractionation and chemical characterization of yeast cellular wall (YCW) from yeast biomass obtained as byproduct in the industrial production of ethanol, as well as the evaluation of functional and physiological properties of the various fractions. YCW was fractionated to obtain glycoprotein (GP), a faction containing glycan plus mannan (G+M), insoluble glycan (IG), soluble glycan (SG), and mannan (M), which were characterized for percent composition, amino acid profile, minerals, fatty acids, and monosaccharides. Proportions between YCW components included fiber (77.8%), with predominance (74%) of soluble fiber, remaining in the material 18 to 20% protein. Total sugar content of YCW was 80.8%/100 g and lipid content was 2.00%. Among the saturated fatty acids, the palmitic and stearic were predominant, among the monounsaturated acids, the palmitoleic and the oleic, and among the polyunsaturated acids, the linoleic acid and a¿linolenic acid. The most abundant mineral elements were calcium, phosphorous, potassium, and iron and the YCW showed to be an excellent source of iron and copper. Fractions obtained from YCW were: M 25.13% and IG 42.92% w/v. Fiber content in the isolated fractions were: M 70.34% soluble fiber, IG 75.2% insoluble fiber, G+M 60.23% soluble fiber, and SG 70.73% soluble fiber. Percentages of reducing sugars were M 70% with 48.4% mannose, IG 28.95% and SG 25.07% glucose. The fraction G+M contained 28.0 g/100g total carbohydrate and 20% reducing sugars. The SG presented the highest solubility and G+M the lowest N solubility and the IG presented the lowest total solids solubility. GS showed the highest water retention capacity (14.36 g/g sample) and the lowest (0.06%) solubility in water. The fraction GP showed retention of 5.33 g/g sample and solubility in water of 83.83%. The SG showed the highest viscosity at 50oC (heating phase). The viscosity at 95oC and the final viscosity (50oC) obeyed the following order: SG > IG > G+M > M > GP and YCW. The IG (12% and 14% w/v) presented the highest gel hardness. The fractions GP and M exhibited the best emulsifying properties, which improved significantly by adding 0.2, 0.4, and 0.6 ovoalbumin to the emulsifying media at 1%. Effects of fiber substitution were evaluated through alteration of control diet (AINP), substituting each YCW fraction with 10% of fiber, which resulted in the diets G+M, M, IG, SG. After 28 days, animals on a G+M diet had gained less body weight than the others. AIN-M (standard modified with 10% cellulose) and M diets promoted the highest growth, followed by AIN-P and IG. The DER of the G+M diet was the lowest along 28 days of experiment. Higher protein digestibility indexes were found for AIN-P, AIN-M, and M. With exception of the G+M diet, hypocolesterolemic and hypolipidemic effects were found for all the diets, compared to the starting point (T0). No significant modification of the intestinal microbiota was verified in any dietary treatment. Great variation was verified among the diets for fecal lipids and cholesterol excretion. The M diet showed greater capacity to excrete cholesterol in the rat feces. Among the SCFA, acetic acid predominated in all treatments, followed by propionic acid and butiric acid. Butiric concentrations were significantly higher in the M, G+M, and G diets compared with AIN-P and AIN-M / Doutorado / Doutor em Alimentos e Nutrição
32

Synthesis of water soluble polymer-bound antiproliferative agents

Johnson, Mark Trevor 31 October 2006 (has links)
Student Number : 9903022H MSc Dissertation School of Chemistry Faculty of Science / Cancer is characterised by the unconstrained growth of cancerous cells, which damages the healthy cells and ultimately the tissue of the host. Chemotherapy forms an essential component in the treatment of this disease, however most anti-tumour drugs suffer from various deficiencies, e.g. increased toxicity, reduced serum half life and poor water solubility. The focus of this project was to address some of these deficiencies by conjugating selected drugs to a water-soluble polymeric carrier. Selected water-soluble biodegradable carriers were synthesized. Copolyaspartamides, polyamidoamines and polyamides were obtained by condensation polymerisation, Michéal–type addition polymerisation and ester amine base-catalysed polymerisation. The nascent water soluble polymers were used to conjugate platinum, ferrocene and tetramethylmelamine derivative, respectively. The percentage drug in each polymer drug conjugate was determined by considering the mass of the drug in the conjugate as a percentage of the total mass of the drug-polymer conjugate. Platinum was linked to the carrier via polymer attached amine, carboxyl and hydroxyl ligands. Platinum content of the conjugates ranged from 7 to 11 % by mass. The ferrocenylation agent, 4-ferrocenylbutanoic acid, and the tetramethylmelamine derivative, 3-(4,6-bis(N,N-dimethylamino)-1,3,5-triazacyclohexatrien-2-yl) propanoic acid was polymer-bound by amidation reactions. Iron content of the ferrocence conjugated ranged from 2 to 12 % by mass. While the drug content based on tetramethylmelamine in the 3-(4,6-bis[N,N-dimethylamino]-1,3,5-triazacyclohexatrien-2-yl) propanoic acid polymer conjugate ranged from 8.4 to 8.6 % by mass. There was a preliminary attempt to coconjugate both, 4-ferrocenylbutanoic acid and 3-(4,6-bis[N,N-dimethylamino]-1,3,5- triazacyclohexatrien-2-yl) propanoic acid to the same polymer. This co-conjugate contained 2.9 % iron and 3.4 % tetramethylmelamine by mass.
33

Le rôle de l'Epoxyde hydrolase soluble (sEH) dans la physiopathologie des calcifications vasculaires / The role of soluble Epoxide Hydrolase (sEH) in the pathophysiology of vascular calcifications

Varennes, Olivier 17 December 2018 (has links)
L'Epoxide Hydrolase soluble (sEH) est une enzyme exprimée dans les vaisseaux. Elle possède un domaine hydrolase à l'extrémité COOH-term (sEH-H) qui métabolise des facteurs vasodilatateurs et anti-inflammatoires comme les acides époxyeicosatriénoïques (EETs). Elle possède également un domaine phosphatase à l'extrémité NH2-term (sEH-P) dont le rôle biologique n'est pas totalement élucidé. Afin de comprendre le rôle de sEH-H et sEH-P dans la calcification vasculaire, des anneaux aortiques de rats et des cellules musculaires lisses vasculaires humaines (CMLVh) ont été exposés à des conditions procalcifiantes pendant 7 et 14 jours respectivement. Le N-acétyl-S-farnesyl-L-cystéine (AFC), un inhibiteur de sEH-P, et le trans-4-(4-(3-adamantan-1-yl-ureido)-)cyclohexyloxy) acide benzoïque (t-AUCB), un inhibiteur de sEH-H, ont été utilisés entre 0,1 et 10 μM. En condition procalcifiante, l'AFC réduit de façon dose-dépendante la calcification vasculaire. Au contraire, le t-AUCB augmente de façon dose-dépendante la minéralisation au sein des anneaux aortiques. Une augmentation de l'activité TNAP a été observée dans les surnageants de culture des anneaux aortiques avec le t-AUCB. Sur les anneaux désendothélialisés ou sur les cultures de CMLVh, les inhibiteurs n'ont pas d'effet sur la calcification, soulignant le rôle crucial joué par les facteurs endothéliaux métabolisés par la sEH. L'ensemble de nos résultats montrent que l'inhibition pharmacologique de la sEH-H augmente la calcification vasculaire in vitro en augmentant la biodisponibilité des EETS. Au contraire, l'inhibition de la sEH-P protège contre la calcification vasculaire à travers un mécanisme dépendant de l'endothélium / Expressed in the vasculature, soluble epoxide hydrolase (sEH) exhibits a COOH-terminal hydrolase domain metabolizing endothelial vasodilator and anti-inflammatory factors like epoxyeicosatrienoic acids (EETs) and, a NH2-terminal phosphatase domain whose biological role remains unclear. To assess the role of sEH phosphatase and hydrolase domains in vascular calcification, rat aortic rings and hVSMCs were exposed to procalcifying culture media for 7 and 14 days, respectively. N-acetyl-S-farnesyl-L-cysteine (AFC), an inhibitor of the phosphatase domain, and trans-4-(4-(3-adamantan-1-yl-ureido)-cyclohexyloxy)-benzoic acid (t-AUCB), a hydrolase domain inhibitor, were used at concentrations ranging from 0.1 to 10 μM. Under procalcifying culture condition, AFC significantly and dose-dependently reduces aortic calcification. Conversely, addition of t-AUCB results in a significant and dose-dependent increase in aortic calcification in rats, without modification of tissue viability. A concomitant increase in TNAP activity was observed in supernatants of aortic rings cultured in the presence of t-AUCB. On de-endothelialized aortic rings or hVSMCs cultures, both inhibitors had no significant effect on the calcification process, pointing out the crucial role played by endothelial factors metabolized by sEH in the control of this biomineralization process. Together, our data demonstrates that pharmacological inhibition of sEH hydrolase increases vascular calcification in vitro by majoring the bioavailability of endothelium- derived EETs. Contrarily, the inhibition of sEH phosphatase is protective against vascular calcification through an endothelium-dependent mechanism.
34

Subnormal Structure of Finite Soluble Groups

Wetherell, Chris, chrisw@wintermute.anu.edu.au January 2001 (has links)
The Wielandt subgroup, the intersection of normalizers of subnormal subgroups, is non-trivial in any finite group and thus gives rise to a series whose length is a measure of the complexity of a group's subnormal structure. Another measure, akin to the nilpotency class of nilpotent groups, arises from the strong Wielandt subgroup, the intersection of centralizers of nilpotent subnormal sections. This thesis begins an investigation into how these two invariants relate in finite soluble groups. ¶ Complete results are obtained for metabelian groups of odd order: the strong Wielandt length of such a group is at most one more than its Wielandt length, and this bound is best possible. Some progress is made in the wider class of groups with p-length 1 for all primes p. A conjecture for all finite soluble groups, which may be regarded as a subnormal analogue of the embedding of the Kern, is also considered.
35

Synthesis and Solution Behavior of Doubly Responsive Hydrophilic Block Copolymers

Jiang, Xueguang 01 August 2010 (has links)
This dissertation presents the synthesis of stimuli-sensitive hydrophilic polymers, particularly doubly responsive hydrophilic block copolymers, by controlled radical polymerizations and the study of their solution behavior in water. By incorporating a small amount of stimuli-responsive groups into the thermosensitive block of a hydrophilic block copolymer, the lower critical solution temperature (LCST) of the thermosensitive block can be tuned by a stimulus and multiple micellization/dissociation transitions can be achieved by combining two external triggers. Chapter 1 describes the synthesis and thermosensitive properties of two new watersoluble polystyrenics with a short oligo(ethyl glycol) pendant from each repeat unit and the study of hydrophobic end group effects on cloud points of thermosensitive polystyrenics. Well-defined polymers were prepared from monomer-based initiators via nitroxide-mediated polymerization and the alkoxyamine end groups were removed by tri(n-butyl)tin hydride, yielding thermoresponsive polystyrenics with essentially no end groups. The results showed that hydrophobic end groups could significantly change the cloud points and the molecular weight dependences of cloud points of polystyrenics. Chapter 2 presents the synthesis of thermo- and light-sensitive hydrophilic block copolymers, poly(ethylene oxide)-b-poly(ethoxytri(ethylene glycol) acrylate-co-onitrobenzyl acrylate), and their responsive behavior in dilute aqueous solutions. Dynamic light scattering and fluorescence spectroscopy studies showed that these copolymers were molecularly dissolved in water at lower temperatures and self-assembled into micelles at temperatures above the LCST of the thermosensitive block. Upon UV irradiation, the oiv nitrobenzyl group was cleaved and the LCST of the thermosensitive block was increased, causing the dissociation of micelles into unimers. The resultant copolymers underwent thermo-induced reversible micellization at higher temperatures. Chapter 3 describes multiple micellization/dissociation transitions of thermo- and pH-sensitive hydrophilic block copolymers, poly(ethylene oxide)-b-poly(methoxydi(ethylene glycol) methacrylate-co-methacrylic acid), in response to temperature and pH changes. The LCST of the thermosensitive block can be reversibly tuned and precisely controlled by solution pH. Chapter 4 presents the study on multiple sol-gel-sol transitions of a 20.0 wt % aqueous solution of poly(ethylene oxide)-b-poly(ethoxytri(ethylene glycol) acrylate-co-o-nitrobenzyl acrylate) induced by temperature changes and UV irradiation. The solution underwent thermo-induced sol-gel-sol transitions. Upon UV irradiation to dissociate micelles, the gel was transformed into a free-flowing liquid, which upon heating underwent sol-gel-sol transitions again.
36

The behavior and separation of polystyrene in mixed solvent systems

Hamilton, Patrick Neal 15 May 2009 (has links)
Non-polar phase selective solubility of modified poly(4-n-alkylstyrene) supports can be measured using fluorescent dyes as catalyst surrogates with thermomorphic and latent biphasic systems. By modifying the solvent compositions in heptane/ethanol and heptane/N, N-dimethylacetamide, increased non-polar phase selective solubility of modified polystyrene supports can be attained. Likewise, by varying the structure and length of the pendant alkyl chain, an increase in non-polar phase selective solubility is measured. These heptane soluble polymer supports can be useful for applications involving heptane soluble polymer-bound reagents and catalysts. Various polar and non-polar polymer supports were synthesized with an attached solvatochromic catalyst surrogates to determine the solvent accessibility of the supported species in pure and mixed solvents. The results of these studies indicate that in pure solvents, the influence of both polar and non-polar polymer supports on the solvent microenvironment of these polymer-supported probes is minimal. In mixed solvent systems, a polymer-like solvent microenvironment is measured in solvent mixtures comprised of solvents the polymer has unfavorable interactions. Poly(4-n-alkylstyrene) and internally functionalized polyisobutylene supports are two such polymer supports that exhibit this behavior. For terminally functionalized polymers in mixed solvents, the solvatochromic behavior does not indicate a collapsed structure. In mixed solvents, there is minimal influence of the polymer support on the solvent microenvironment of these terminally functionalized polymers. The application of soluble polyisobutylene supported copper complexes in the ATRP polymerization of styrene was investigated. Using the difference in solubility of the product polystyrene and the polyisobutylene copper complex in heptane, a solid/liquid separation of the soluble copper complex from the solid product was achieved. The results of these polymerizations indicate that the polyisobutylene copper complex behaves exactly like a low molecular weight copper complex in terms of control over molecular weight and molecular weight distribution. After the polymerizations, the polyisobutylene complexes could be separated as a heptane solution and recycled in multiple polymerizations of styrene.
37

Organometallic catalysis in aqueous solution : reactions and mechanisms of water-soluble molybdocenes /

Breno, Kerry L., January 2004 (has links)
Thesis (Ph. D.)--University of Oregon, 2004. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 213-252). Also available for download via the World Wide Web; free to University of Oregon users.
38

Crosstalk between VEGF and BMP9 Signalling in the Context of Preeclampsia

Sotov, Valentin 28 November 2013 (has links)
Preeclampsia is a pregnancy related disorder, characterized by proteinuria and hypertension. The pathogenesis of preeclampsia is poorly understood; however, two proteins, called sFlt-1 and sEng, were found to be highly elevated in the maternal plasma weeks prior to the onset of clinical symptoms. sFlt-1 and sEng are thought to inhibit VEGF and TGF-β receptor signalling respectively. In order to elucidate how these proteins may contribute to preeclampsia, we looked at their ability to affect the secretion of endothelin-1 (ET-1), a powerful vasoconstrictor, shown to be dysregulated in preeclampsia. We found that both TGF-β1 and BMP9, a recently described ligand for sEng, induce ET-1 secretion through Smad1/5/8 and p38 pathways. Moreover, we report that sEng and VEGF can efficiently block ET-1 secretion, induced by BMP9. We propose that the balance between VEGF and BMP9 signalling is disturbed during preeclampsia, leading to excessive release of ET-1, which in turn may cause hypertension.
39

Crosstalk between VEGF and BMP9 Signalling in the Context of Preeclampsia

Sotov, Valentin 28 November 2013 (has links)
Preeclampsia is a pregnancy related disorder, characterized by proteinuria and hypertension. The pathogenesis of preeclampsia is poorly understood; however, two proteins, called sFlt-1 and sEng, were found to be highly elevated in the maternal plasma weeks prior to the onset of clinical symptoms. sFlt-1 and sEng are thought to inhibit VEGF and TGF-β receptor signalling respectively. In order to elucidate how these proteins may contribute to preeclampsia, we looked at their ability to affect the secretion of endothelin-1 (ET-1), a powerful vasoconstrictor, shown to be dysregulated in preeclampsia. We found that both TGF-β1 and BMP9, a recently described ligand for sEng, induce ET-1 secretion through Smad1/5/8 and p38 pathways. Moreover, we report that sEng and VEGF can efficiently block ET-1 secretion, induced by BMP9. We propose that the balance between VEGF and BMP9 signalling is disturbed during preeclampsia, leading to excessive release of ET-1, which in turn may cause hypertension.
40

Fluid placement and diversion in matrix acidizing : numerical modelling of particulate diverting agent behaviour

Chatzichristos, Christos January 1996 (has links)
No description available.

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