Global ETD Search

1	Etude des mécanismes de structuration d’assemblages β-lactoglobuline-gomme d’Acacia en présence d’un flavonoïde, la quercétine / Structuration mechanism study of protein-polysaccharide assemblies in presence of flavonoid, quercetin Aberkane, Leïla 08 October 2010 (has links) Les flavonoïdes sont des ingrédients prometteurs pour différentes applications alimentaires et non alimentaires, grâce à leurs propriétés antioxydantes et biologiques. Cependant, la formulation de ces molécules est difficile à réaliser en raison de leur faible solubilité dans la plupart des solvants. Afin de remédier à cette difficulté, l’approche suivie dans cette étude est l’incorporation des flavonoïdes dans des particules à base de biopolymères (protéine-polysaccharide), stables et fonctionnelles. Le principal objectif de cette thèse était d’acquérir des connaissances à différentes échelles d’étude sur les mécanismes d’interaction et d’assemblage entre un flavonoïde, la quercétine, et deux biopolymères,B-lactoglobuline (BLG) et la gomme d’Acacia (AG). Dans une première étape, nous avons pu mettre au point des particules submicroniques (Dh : ~250 nm) de gomme d’Acacia-quercétine (GAQ) possédant une structure assimilée à un assemblage « cœur-couronne » et traduisant un comportement correspondant à celui de particules molles. Dans une seconde étape, nous avons étudié les mécanismes d’assemblage des particules de GAQ avec la BLG à pH 4,2 et à 25 °C. Les paramètres thermodynamiques d’interaction ont été déterminés par calorimétrie de titration isotherme (ITC) et montrent des isothermes de liaison caractérisées par une séquence exothermique-endothermique. Les différentes entités structurales formées durant la complexation entre la GA et la BLG ou la GAQ et la BLG ont été caractérisées en utilisant la même approche par titration que pour l’ITC. Enfin, des mesures par spectroscopie infra-rouge à transformée de Fourier (FTIR) ont montré une modification de la structure secondaire de la BLG après interaction avec la GA et la GAQ. D’importantes pertes de structures (hélices-α et feuillets-β), encore plus marquées en présence de quercétine / Flavonoids are promising ingredients in food and non food applications through their antioxidative and biological properties. However, their negligible solubility in most solvent renders problematic technological developments. In order to overcome this drawback, the approach followed in this study was the incorporation of flavonoids in stable and functional particles based on biopolymers (protein-polysaccharide). The main objective of this thesis was to acquire knowledge at different scales to study the mechanisms of interaction and linkage between a flavonoid, quercetin, and two biopolymers, B-lactoglobulin (BLG) and Acacia gum (AG). In a first step, we were able to develop submicronic particles (Dh : ~250 nm) of quercetin-Acacia gum (GAQ) based on a core of quercetin and a shell of Acacia gum, reflecting a behavior of soft particles. In a second step, we investigated the assembly mechanisms GAQ with BLG at pH 4.2 and 25 ° C. The thermodynamic parameters of interaction were determined by isothermal titration calorimetry (ITC) and show binding isotherm characterized by an exothermic-endothermic sequence. The various structural entities formed during the complexation between GA and BLG or BLG and GAQ were characterized using the same approach as for the ITC titration. Finally, measurements using infra-red Fourier transform (FTIR) showed changes in the secondary structure of BLG after interaction with the GA and the GAQ. There was a significant loss of secondary structures (α-helices and β-sheets), even more pronounced in presence of quercetin Assemblages protéine-polysaccharide Flavonoïde Β-lactoglobuline Gomme d’Acacia Caractérisation thermodynamique Transitions structurales Protein-polysaccharide assemblies Flavonoid Β-lactoglobuline Acacia gum Thermodynamic characterization Structural transitions
2	Analysis of a novel thermoelectric generator in the built environment Lozano, Adolfo 05 October 2011 (has links) This study centered on a novel thermoelectric generator (TEG) integrated into the built environment. Designed by Watts Thermoelectric LLC, the TEG is essentially a novel assembly of thermoelectric modules whose required temperature differential is supplied by hot and cold streams of water flowing through the TEG. Per its recommended operating conditions, the TEG nominally generates 83 Watts of electrical power. In its default configuration in the built environment, solar-thermal energy serves as the TEG’s hot stream source and geothermal energy serves as its cold stream source. Two systems-level, thermodynamic analyses were performed, which were based on the TEG’s upcoming characterization testing, scheduled to occur later in 2011 in Detroit, Michigan. The first analysis considered the TEG coupled with a solar collector system. A numerical model of the coupled system was constructed in order to estimate the system’s annual energetic performance. It was determined numerically that over the course of a sample year, the solar collector system could deliver 39.73 megawatt-hours (MWh) of thermal energy to the TEG. The TEG converted that thermal energy into a net of 266.5 kilowatt-hours of electricity in that year. The second analysis focused on the TEG itself during operation with the purpose of providing a preliminary thermodynamic characterization of the TEG. Using experimental data, this analysis found the TEG’s operating efficiency to be 1.72%. Next, the annual emissions that would be avoided by implementing the zero-emission TEG were considered. The emission factor of Michigan’s electric grid, RFCM, was calculated to be 0.830 tons of carbon dioxide-equivalent (CO2e) per MWh, and with the TEG’s annual energy output, it was concluded that 0.221 tons CO2e would be avoided each year with the TEG. It is important to note that the TEG can be linearly scaled up by including additional modules. Thus, these benefits can be multiplied through the incorporation of more TEG units. Finally, the levelized cost of electricity (LCOE) of the TEG integrated into the built environment with the solar-thermal hot source and passive ground-based cold source was considered. The LCOE of the system was estimated to be approximately $8,404/MWh, which is substantially greater than current generation technologies. Note that this calculation was based on one particular configuration with a particular and narrow set of assumptions, and is not intended to be a general conclusion about TEG systems overall. It was concluded that while solar-thermal energy systems can sustain the TEG, they are capital-intensive and therefore not economically suitable for the TEG given the assumptions of this analysis. In the end, because of the large costs associated with the solar-thermal system, waste heat recovery is proposed as a potentially more cost-effective provider of the TEG’s hot stream source. / text Thermoelectric generator TEG Novel thermoelectric generator Thermoelectrics Thermoelectric effect Thermoelectric modules Thermoelectric device Patent application Hot stream source Cold stream source EIA EERE Systems-level analysis Energy balance Control volume analysis Thermodynamic analysis Insolation data Insolation incident on a panel Incident insolation Extraterrestrial insolation NREL Ambient temperature data NOAA Renewable energy sources Energy generation technology Electricity generation technology Thermal energy Coupled system Emissions Greenhouse gas GHG Emissions analysis Zero-emission Emissions avoided Emission factor EF Reliability First Corporation RFC Built environment Integrated into the built environment Solar-thermal energy Solar collector system Photovoltaic thermal PVT panel Thermal storage tank Geothermal energy Geothermal heat pump GHP Ground source heat pump GSHP Numerical analysis Numerical model MATLAB Finite-difference Euler explicit Electric grid Annual energetic performance Annual electricity generation Operating efficiency System efficiency Thermodynamic characterization Economic analysis Levelized cost of energy LCOE Waste heat recovery Carbon dioxide equivalent CO2e Capital costs Installed costs Operating and maintenance costs

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Etude des mécanismes de structuration d’assemblages β-lactoglobuline-gomme d’Acacia en présence d’un flavonoïde, la quercétine / Structuration mechanism study of protein-polysaccharide assemblies in presence of flavonoid, quercetin

Analysis of a novel thermoelectric generator in the built environment