Um die anderen Arten von Veröffentlichungen zu diesem Thema anzuzeigen, folgen Sie diesem Link: Solvent media.
Dissertationen zum Thema „Solvent media“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit Top-50 Dissertationen für die Forschung zum Thema "Solvent media" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Sehen Sie die Dissertationen für verschiedene Spezialgebieten durch und erstellen Sie Ihre Bibliographie auf korrekte Weise.
1
Bhattarai, Ajaya. „Polyelectrolyte-surfactant interactions in mixed solvent media“. Thesis, University of North Bengal, 2010. http://hdl.handle.net/123456789/1321.
Der volle Inhalt der Quelle
2
Fowler, Sandra Dee. „COPPER SOLVENT EXTRACTION FROM CHLORIDE-SULFATE MEDIA“. Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275369.
Der volle Inhalt der Quelle
3
Choudhury, Ankan. „Physico-chemical investigation of solute-solute, solute-solvent and solvent-solvent interactions of some compounds in non-aqueous and mixed solvent media“. Thesis, Th 541.34:C552p, 2005. http://hdl.handle.net/123456789/704.
Der volle Inhalt der Quelle
4
Dioum, Ndeye. „Biocatalysis of immobilized lipoxygenase in organic solvent media“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0033/MQ64344.pdf.
Der volle Inhalt der Quelle
5
Khamessan, Ali. „Chlorophyllase biocatalysis of chlorophyll in organic solvent media“. Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28798.
Der volle Inhalt der QuelleAnnotation:
Cette recherche comprend l'etude de la bioacatalyse de la chlorophyllase partiellement purifiee a partir d'algue (Phaeodactylum tricornutum) dans differents milieux organiques incluant les solvants miscibles et non miscibles a l'eau et les systemes micellaires tertiaires. Les quantites optimales d'eau et de solvant, choisi en fonction de son degre d'hydrophobicite et incluant l'acetone, l'ethanol, le propanol, le butanol, le pentanol, l'hexanol, le toluene, le pentane, l'hexane, l'heptane et l'octane, necessaire a la catalyse de l'effet hydrolytique de la chlorophyllase, ont ete mesurees. Les valeurs d $V sb{ rm max}$ obtenues mesurant l'activite hydrolytique de la chlorophyllase sont plus elevees chez les solvants miscibles a l'eau (log P 0.8). L'activite hydrolytique de la chlorophyllase decroit d'approximativement 12 fois lorsque le nombre de carbone pour les alcools, passent de 2 a 5. Certains resultats a partir du FTIR ("Fourier transform infrared spectroscopy") tendent a montrer que le phytol pourrait agir comme un donneur d'electron, ainsi, si un compose nucleophilique approprie est ajoute a un syteme biphasique, la solubilite de la chlorophylle dans l'hexane augmentera et l'activite hydrolytique de la chlorophyllase augmentera. En milieu biphasique (hexane/eau), l'addition de solvants polaires tels que l'acetone, l'ethanol, et le propanol augmente l'activite de la chlorophyllase et ce seulement a certaines concentrations. La mesure optimale de l'activite hydrolytique de la chlorophyllase en milieu micellaire tertiaire (tampon/hexane/surfactant) utilisant les polysorbates et les Spans ainsi que differentes chai nes hydrophobiques comme surfactant indique que les concentrations necessaires de surfactants sont dependantes a la fois de la chai ne hydrophobique et du groupement polaire. Toutefois, l'utilisation du Span 85 s'est avere plus approprie et les valeurs de $V sb{ rm max}$ obtenues mesurant l'activite enzymatique de la chlorophyllase sont 288 fois
6
Spadina, Mario. „Solvation and Ion Specificity in Complex Media“. Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS020/document.
Der volle Inhalt der QuelleAnnotation:
Le but de cette thèse était de créer des modèles pour deux applications qui apparaissent couramment en chimie séparative, à savoir la séparation solide-liquide et la séparation liquide-liquide. L'avantage de la modélisation est manifeste dans les deux cas. L'étude fondamentale des propriétés des ions et de leur solvatation dans les milieux complexes, en tenant compte de façon simplifié des différents effets mis en jeu, nous a permis de construire un cadre qui utile aussi bien aux chimistes en laboratoire qu’aux ingénieurs lors de la conception des procédés. Nous avons adapté cette stratégie sur deux systèmes différents, qui peuvent tous deux être considérés comme complexes. Le premier système modèle pour étudier la séparation solide-liquide était des nanotubes de TiO2 dispersés dans une solution aqueuse. Ce système a été étudié au moyen de la Théorie de la Fonctionnelle de la Densité Classique couplée à une méthode de régulation de charge, au sein de l'ensemble Grand-Canonique. La méthode s'est avérée efficace pour établir la description complète des propriétés de charge des nanotubes de TiO2. Dans ce cas, nous nous sommes intéressés à obtenir la description de l'ion à l'intérieur des nanotubes chargés sous l'influence du champ électrique (créé par les nanotubes). Les calculs ont prédit des effets tels que la différence de charge de surface entre la surface externe et la surface interne, ou la violation de l'électroneutralité à l'intérieur des nanotubes. Il a été démontré que le modèle était en accord avec les données expérimentales. De plus, la méthode peut être utilisée directement pour prédire diverses techniques de titrage. Une simple généralisation de l'approche proposée permettra d'étudier l'efficacité d'adsorption réelle du procédé de séparation solide-liquide. Le second système modèle concerne l'étude du procédé d'extraction liquide-liquide et il comprend trois parties distinctes. Les trois parties ont été consacrées aux cas des extractants non ioniques, puis acides (échangeurs d'ions), et enfin aux mélanges synergiques d'extractants. Un modèle simple de thermodynamique statistique, dans lequel nous avons incorporé certains des concepts bien établis en chimie colloïdale, a fourni une approche de type matière molle pour calculer le processus à l'échelle de l'ingénieur. Nous avons développé une approche classique d'équilibres simples pour une compréhension plus large et plus intuitive de la formation des agrégats polydisperses dans l'extraction liquide-liquide. La principale conclusion présentée est que l’on doit proposer un nouveau paradigme pour la chimie : à l'équilibre, de nombreux agrégats de composition très différente mais similaires en énergie libre, coexistent. Avec la polydispersité obtenue, nous avons ainsi proposé un outil pour étudier un comportement plus "global" de l'extraction liquide-liquide. Cela nous a poussés à passer des considérations classiques d'isothermes d'extraction à celles plus précises des " cartes " d’extraction. Un grand soin a été apporté à l'étude de la synergie puisqu'il s'agit d'une important question depuis 60 ans dans la communauté scientifique et industrielle de la séparation. A notre connaissance, la première rationalisation quantitative de la synergie d’extraction a été proposée dans le cadre de cette thèse. Les effets sous-jacents des contrôles enthalpique et entropique sur la structuration des phases organiques ont été découplés et étudiés en détail. Nous espérons que cette thèse a démontré l'importance de la modélisation mésoscopique sur des exemples pratiques utilisés à la fois par les chimistes et les ingénieursThe object of this thesis was to create models for two applications which readily appear in separation chemistry, namely the solid-liquid and the liquid-liquid extractions. The benefit of modelling in both cases is twofold. Studying the fundamental properties of ions and their solvation properties in the complex media, and simplifying the expression for important effects, enables us to construct the framework which can be used by both chemists in the laboratory, as well as the chemical engineers in the process design. For two applications we adapted two different systems, both of which can be considered as complex. The model system to study the solid-liquid separation were TiO$_{mathrm{2}}$ nanotubes dispersed in the aqueous solution. This system was studied by the means of Classical Density Functional Theory coupled with the charge regulation method, within the Grand-canonical ensemble. Indeed, the method proved to be successful in establishing the full description of the charge properties of TiO$_{mathrm{2}}$ nanotubes. In this case, we were interested in obtaining the description of ion inside the charged nanotubes under influence by the electric field (exhibited by nanotubes). Calculations predicted effects such as the difference in surface charge between the outer and the inner surface, or the violation of electroneutrality inside the nanotubes. It was demonstrated that the model was in the agreement with the experimental data. Moreover, the method can be directly used to predict titration for various techniques. A simple generalization of the proposed approach can be used to study the actual adsorption efficiency of the solid-liquid separation process. The model system to study the liquid-liquid extraction process included three distinct parts. The three parts were devoted to the cases on non-ionic, acidic ion exchangers, and finally the synergistic mixtures of extractants. Simple bulk statistical thermodynamics model, in which we incorporated some of the well-established concepts in colloidal chemistry provided a soft-matter approach for the calculation of actual engineering-scale processes. Were have expanded a classical simple equilibria approach to broader, more intuitive polydisperse aggregates formation that underlines the liquid-liquid extraction. The key finding can be presented as a current opinion or newly-proposed paradigm: at equilibrium, many aggregates completely different in composition but similar in free energy coexist. With obtained polydispersity, we were equipped with a tool to study a more 'global' behavior of liquid-liquid extraction. This urged us to pass our considerations of historical extraction isotherms to extraction 'maps'. Great care was devoted to the study of synergy since it is a 60-year old ongoing question in the separation industrial and science community. To our best knowledge, the first quantitative rationalization total synergistic extraction was proposed within this thesis. Underlying effects of enthalpy and entropy control on the organic phase structuring were decoupled and studied in detail. Hopefully, this thesis demonstrated the importance of mesoscopic modelling to assist both chemists and chemical engineers in practical examples
7
Arriagada, Strodthoff Paula. „Optimization of biocatalysis of chlorophyllase in neat organic solvent media“. Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81263.
Der volle Inhalt der QuelleAnnotation:
The biocatalysis of a crude chlorophyllase extract, obtained from the biomass culture of Phaeodactylum tricornutum, in neat organic solvent media was investigated. The addition of selected excipients, including crown ether (enzyme:crown ether, 135:1--2.7:1, w/w), dextran (enzyme:dextran, 1:2--1:0.25, w/w), Span 40 and Span 60 (enzyme:Span, 1:2, w/w) and sodium bis (2-ethylhexyl) sulfosuccinate (enzyme:AOT, 1:12.6, w/w), to the crude solid enzyme preparation decreased the chlorophyllase activity. The effects of selected parameters, including solvent hydrophobicity (Log P, 2.40--4.45), initial water activity (aw, 0.44--0.97), agitation speed (0--200 rpm), reaction temperature (25--45°C) and enzyme concentration (1.67--5.3 mg solid enzyme/mL) on chlorophyllase activity, were investigated using a crude solid enzyme. The experimental findings showed that the highest chlorophyllase specific activity of 362.4 nmol hydrolyzed chlorophyll/g solid enzyme/min and bioconversion yield of 90.7% were obtained with the hexane/octanone mixture (98.7:1.3, v/v), aw of 0.90, agitation speed of 200 rpm, reaction temperature of 35°C and enzyme concentration of 3.33 mg solid enzyme/mL.
8
Nandi, Prabir. „Solution properties of sodium carboxymethylcellulose in acetonitrile-water mixed solvent media“. Thesis, University of North Bengal, 2009. http://hdl.handle.net/123456789/1350.
Der volle Inhalt der Quelle
9
Gurung, Bhoj Bahadur. „Physico-chemical studies on the solute-solvent interactions of some electrolytes in various single and binary solvent media“. Thesis, University of North Bengal, 2006. http://hdl.handle.net/123456789/747.
Der volle Inhalt der Quelle
10
Brahman, Dhiraj. „PHYSICO-CHEMICAL STUDIES OF SOME SCHIFF BASE COMPLEXES OF TRANSITION METALS IN PURE AND MIXED SOLVENT MEDIA“. Thesis, University of North Bengal, 2013. http://hdl.handle.net/123456789/973.
Der volle Inhalt der Quelle
11
Chatterjee, Amritendu. „Solution properties of sodium carboxymethylcellulose in methanol-water mixed solvent media“. Thesis, University of North Bengal, 2012. http://hdl.handle.net/123456789/1573.
Der volle Inhalt der Quelle
12
Ionidis, Georgios. „The productivity of biocatalytic oxyfunctionalization reactions in polar solvent / aqueous media /“. Zürich : ETH, 2006. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16853.
Der volle Inhalt der Quelle
13
Bao, Haihong. „Biocatalysis of tyrosinase in organic solvent media using phenolic substrate models“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ50716.pdf.
Der volle Inhalt der Quelle
14
Vega, Mireille. „Biocatalysis of immobilized lipoxygenase and hydroperoxide lyase in organic solvent media“. Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18733.
Der volle Inhalt der QuelleAnnotation:
The secondary structure of commercially purified soybean lipoxygenase (LOX) type I-B as well as its immobilization and biocatalysis in organic solvent media (OSM) were investigated. The Fourier transform infrared (FT-IR) spectra of LOX obtained in chloroform, methanol and acetonitrile showed an absorption band at 1617 cm-1 indicative of significant protein aggregation, whereas spectra of lipoxygenase in hexane and octane exhibited substantially less aggregate formation. Variable-temperature infrared studies of lipoxygenase in D2O show that the predominately alpha-helical structure of the protein undergoes an irreversible transition to intermolecular beta-sheet at and above 65 Celsius. The biocatalysis of free and immobilized (EupergitC250L/EDA) LOXs was investigated in different mixtures of hexane and a selected cosolvent (95:5, v/v). The results showed a 1.5 and a 1.6-fold increase in the enzymatic activity of free and immobilized LOXs, respectively, using a mixture of hexane and 1,4-dioxane as compared to that in hexane. To determine the enzymatic production of hydroperoxides of linoleic acid in OSM, the xylenol orange (FOX) assay was optimized. An increase in the proportion of methanol from 0 to 75% in the FOX reagent resulted in a 93% increase in the molar absorption coefficients at 560 nm. Moreover, when perchloric acid was used, the source of ferrous ions and presence of denatured LOX had little effect on the sensitivity of the FOX assay whereas sensitivity decreased by 40 and 46%, respectively, with sulfuric acid. In addition, the immobilization of an enriched enzymatic extract of Penicillium camemberti, containing LOX and hydroperoxide lyase (HPL) activities, and its biocatalysis in OSM were investigated. The highest immobilization efficiency (173.9 and 694.4% for LOX and HPL, respectively) was obtained with unmodified EupergitC250L. The increase in thermal stability of both LOX and HPL activities were obtained by the immobilization of the enriched enzymLa structure secondaire de la lipoxygenase (LOX) de soya purifiée commerciale de type I-B, de même que son immobilisation et sa biocatalyse en milieu de solvant organique (OSM), ont été investiguées. Les spectres infrarouges de transformée de Fourier (FT-IR) de la LOX obtenus en chloroforme, méthanol et acétonitrile ont montrés une bande d'absorption à 1617 cm-1 qui indique une agrégation significative de protéines, tandis que les spectres de la LOX en hexane et octane ont montrés sensiblement moins de formation d'agrégats. Les études infrarouges en Variation-Température de la lipoxygénase dans le D2O ont également démontrées que la structure prédominante en alpha-hélices de la protéine subit une transition irréversible, à et au-dessus de 65 Celsius, vers les beta-feuillets intermoléculaires. La biocatalyse de la LOX de soya libre et immobilisée (LOXi; EupergitC250L/EDA) a été étudiée dans différents mélanges d'hexane et de cosolvent sélectionné (95:5, v/v). Les résultats ont dévoilé des augmentations de 1.5 et 1.6 fois de l'activité enzymatique de la LOX libre et immobilisée, respectivement, en utilisant un mélange d'hexane et de 1,4-dioxane par rapport à celui en hexane. Pour déterminer la production enzymatique des hydroperoxides d'acide linoléique en OSM, la méthode par oxydation ferreuse avec l'orange de xylenol (FOX) a été optimisée. Une augmentation de la proportion de méthanol dans le réactif de FOX de 0 à 75% a eu comme effet une augmentation de 93% des coefficients d'absorption molaires à 560 nm. De plus, quand l'acide perchlorique a été employé, la source des ions ferreux et la présence de la LOX dénaturée n'ont eu que peu d'effet sur la sensibilité de la méthode de FOX tandis que la sensibilité a diminué de 40 et de 46%, respectivement, avec l'utilisation de l'acide sulfurique pour ces mêmes interférences. En outre, l'immobilisation d'un extrait enzymatique enrichi de Penicillium camemb
15
Sabally, Kebba. „Lipase-catalyzed synthesis of selected phenolic lipids in organic solvent media“. Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102161.
Der volle Inhalt der QuelleAnnotation:
Lipase-catalyzed esterification and transesterification reactions of selected phenolic acids with lipids were investigated in organic solvent media. The esterification of linoleyl alcohol with dihydrocaffeic acid (DHA) in neat hexane medium resulted in highest esterification yield (EY) of 17% when a Candida antarctica lipase (Novozym 435) was used to catalyze the reaction. The use of co-solvents t-butanol and 2-butanone with hexane resulted in a dramatic increase in EY. The highest EY of 83% was obtained in hexane:2-butanone mixture of 85:15 (v/v) using Novozym 435; however lower EY (40%) was obtained when a lipase from Rhizomucor meihei (Lipozyme IM 20) was used. Increasing the amount of the co-solvent 2-butanone in the hexane:2-butanone mixture to 75:25 (v/v) resulted in a lower EY of 75% with Novozym 435; using the same enzyme, the esterification of a more unsaturated alcohol, linolenyl alcohol, with DHCA in the hexane:2-butanone mixture of 75:25 (v/v) resulted in EY of 76% which was similar to that obtained with linoleyl alcohol as lipid substrate. The esterification of DHCA and ferulic acid with linolenyl alcohol in the hexane:2-butanone mixture of 65:35 (v/v) resulted in an EY of 58 and 16%, respectively. Both linoleyl and linolenyl alcohols demonstrated mass action effects with EY of 99% in DHCA: fatty alcohol ratio of 1:8. Using a molar ratio of 1:2, the transesterification reactions of DHCA with trilinolein (TLA) and trilinolenin (TLNA) in hexane:2-butanone mixture of 75:25 (v/v) resulted in total transesterification yields (TYs) of phenolic lipids of 66 and 62%, respectively. The TYs of phenolic monoacylglycerols was higher than that of phenolic diacylglycerols for both TLA and TLNA transesterification reactions. A lower molar ratio of DHCA to TLA of 1:4 resulted in a lower TY of 53%. Using a molar ratio of 1:2, the TY of TLA and TLNA with ferulic acid in hexane:2-butanone mixture of 65:35 (v/v) was 16 and 14%, respectively. An equal molar transesterification reaction of DHCA with flaxseed oil, in a hexane:2-butanone mixture of 75:25 (v/v), resulted in the production of only phenolic monoacylglycerols (19%); however, decreasing the molar ratio resulted in the production of both phenolic mono and diacylglycerols. A molar ratio of DHCA to flaxseed oil (1:8) resulted in a TY of 76%, with 43 and 33% phenolic mono and diacylglycerols, respectively. Changing the solvent mixture of hexane:2-butanone from 65:35 to 85:15 (v/v) resulted in an increased in the TY of phenolic diacylglycerols from 24 to 55% with no significant effect on the TY of phenolic monoacylglycerols. The transesterification reaction resulted in a change in the composition of the C18:3 FA from 53% in the unmodified oil to 60 and 65% in the phenolic mono and diacylglycerols. Transesterification reaction of DHCA with fish liver oil in the solvent mixtures of hexane:2-butanone of 75:25 and 85:15 (v/v) resulted in TY of 56 and 65%, respectively. Transesterification in solvent: mixture of 75:25 resulted in a 40 and 16% TY of phenolic mono and diacylglycerols, respectively, whereas that in the solvent mixture of 85:15 (v/v) resulted in a 38 and 37% TY of phenolic mono and diacylglycerols, respectively. The structures of phenolic lipids of linoleyl and linolenyl alcohols with DHCA were confirmed by LC/MS analysis likewise for the phenolic mono and diacylglycerols from transesterification of DHCA with TLA and TLNA as well as flaxseed and fish liver oils. The phenolic esters of the fatty alcohols demonstrated radical scavenging properties similar to that of alpha-tocopherol but less than for DHCA; however, the phenolic lipids obtained with the use of TLA and TLNA as substrate as well as flaxseed and fish liver oil, demonstrated significant radical scavenging effects but less than that of alpha-tocopherol and DHCA.
16
Safari, Mohammad. „Interesterification of butter fat by commercial microbial lipases in organic solvent media“. Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41762.
Der volle Inhalt der QuelleAnnotation:
The interesterification yield (IY) and changes in fatty acid positional distribution of selected butter fat triacylglycerols were investigated, using a wide range of commercial microbial lipases and organic solvent media. The interesterification of butter fat by lipase from Mucor miehei was carried out in hexane, hexane-chloroform, and hexane-ethyl acetate; the results showed that the addition of 30% of either chloroform or ethyl acetate to the hexane resulted in a 23% increase in the IY. The interesterification of butter fat in a microemulsion co-surfactant system, containing Brij 35 as surfactant and 1-heptanol as co-surfactant, resulted in an increase in the triacylglycerols that contain C18:0 at sn-2 position, located originally at sn-1,3 positions, with a concomitant interchange with C14:0 and C18:1 at the same position. The interesterification of butter fat by lipase from Rhizopus niveus, in a phosphatidylcholine reverse micellar system, showed an increase in C16:0 at the sn-2 position, with a concomitant decrease in the proportion of small chain fatty acids (C4-C10:0); however, the interesterification of butter fat in co-surfactant free microemulsion systems, containing hexane and ionic (phosphatidylcholine) and non-ionic (sorbitol monostearate and polyoxyethylene sorbitan monostearate) surfactants, showed that the interesterified selected triacylglycerols were enriched with C18:0 and C18:1, originally located on sn-1,3 position, at sn-2 position with concomitant interchange with C12:0, C14:0 and C16:0, originally located at the same position. The interesterification of butter fats, in co-surfactant free microemulsion system, by four microbial lipases showed that those catalyzed by lipase from R. niveus demonstrated a 46% increase in the proportion of C18:1 at sn-2 position whereas those catalyzed by enzymes from M. javanicus, R. delemar and M. miehei were enriched with C16:0 at the same position, by 21%, 35% and 41%, respectively. In addition, lipase from
17
Alturaihi, Haydar. „Biocatalysis of lipoxygenase in a model system using selected organic solvent media“. Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=96760.
Der volle Inhalt der QuelleAnnotation:
The biocatalysis of commercially purified soybean lipoxygenase (LOX-1B: EC 1.13.11.12) in ternary micellar and neat organic solvent media, using linoleic acid as a substrate model, was investigated. The organic solvent, used throughout this study, was at different ratios in the ternary micellar system, composed of Tris-HCl buffer solution (0.1 M, pH 9.0) and 10 µM of Tween-40 as the surfactant. The results indicated a 1.4- and 1.7-fold increase in LOX activity when, respectively, 2% iso-octane or 2% hexane was used as the organic solvent in comparison to that in the aqueous medium. The kinetic parameters, including Km and Vmax values, the choice of the surfactant, the optimum reaction temperature and the optimum pH, were investigated. The effects of selected parameters, including initial water activity (aw, 0.23 to 0.75), agitation speed (0 to 200 rpm), reaction temperature (20 to 45ºC) and thermal stability of LOX activity in neat organic solvent, were also studied. The experimental findings showed that the Km and Vmax values in the ternary micellar system containing 2% hexane was calculated to be 7.7 µmol of linoleic acid and 30.0 nmol of linoleic acid hydroperoxides (HPODs)/mg protein/min, respectively, as compare to that of 20.7 µmol of linoleic acid and 8.3 nmol HPODs/mg protein/min in the neat organic solvent, respectively. The experimental results indicated that the major LOX specific activity, for both aqueous and ternary micellar systems, was measured at pH 9.0, with a minor one at pH 6.0 for the aqueous system and at pH 7.0 for the ternary micellar system. The activation energy (Ea) of the reaction system of LOX was 9.87 kJ/mol or 2.36 kcal/mol. The half-life (T50) for LOX was 27.61, 66.63 and 138.6 min for the aqueous, ternary micellar and neat organic media, respectively.La biocatalyse de la lipoxygénase purifiée, obtenus à partir de la graine de soja (LOX-1B: EC 1.13.11.12), a été étudiée en milieux micellaire ternaire et en monophasique organique, en utilisant l'acide linoléique comme substrat modèle. Le solvant organique, utilisé dans cette étude, a été utilisé à différentes concentrations dans le système micellaire ternaire, composé d'une solution tampon Tris-HCl (0,1 M, pH 9,0) et 10 µM d'un surfactant, le Tween-40. Les résultats obtenus ont démontré qu'il y a une augmentation de 1,4 et 1,7 fois de l'activité enzymatique de la LOX en utilisant, respectivement, soit du l'iso-octane à 2% ou soit du l'hexane à 2%, comme le solvant organique en comparaison avec celle en milieux aqueux. Les paramètres cinétiques, comportant les valeurs de Km et de Vmax, le choix de surfactant ainsi que la température et le pH optimal de la réaction ont été étudiés. Les effets de différents paramètres tels que l'activité initiale de l'eau (aw) du 0,23 à 0,75, l'agitation du 0 à 200 rpm, la température de la réaction du 20 à 45ºC et la stabilité thermique de l'activité de la LOX en milieux monophasiques organiques ont été aussi étudiés. Les résultats obtenus tendent à montré que les valeurs de Km et de Vmax en système micellaire ternaire, contenant de l' hexane à 2%, ont été de 7,7 µmol d'acide linoléique et 30,0 nmol d'hydroperyde de l'acide linoléique (HPODs)/mg protéine/min, respectivement, en comparaison à des valeurs de 20,7 µmol d'acide linoléique et 8,3 nmol HPODs/mg protéine/min dans les milieux monophasiques organiques, respectivement. De plus, les résultats expérimentaux ont démontré que l'activité spécifique maximale de la LOX pour les deux systèmes aqueux et micellaire ternaire a été obtenue à pH 9,0, avec aussi une activité minimale à pH 6,0 pour le système aqueux et à pH 7,0 pour le système micellaire ternaire. L'énergie d'activation (Ea) du système de réaction de la LOX était d'une valeur de 9,87 kJ/mol ou 2,36 kcal/mol. La demi-vie (T50) de LOX a été déterminée à 27,61 min dans le milieu aqueux, 66,63 min dans le milieu micellaire ternaire et 138,6 min dans les milieux monophasiques organiques.
18
Kuldamrong, Watchareeya. „Immobilization, stabilization and biocatalysis of hydroperoxide lyase in neat organic solvent media“. Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106486.
Der volle Inhalt der QuelleAnnotation:
The stabilization, immobilization and biocatalysis of hydroperoxide lyase (HPL) of the enzymatic extract, from Penicillium camemberti, in neat organic solvent media (NOSM) were investigated. The effects of lyoprotectants, KCl and dextran 1 kDa, on HPL activity and its stability were studied. The addition of KCl to the HPL enzymatic protein 70:1 (w/w), prior to its lyophilization, enhanced its activity by 6.53-fold, whereas the use of dextran resulted in its inactivation. The thermostability of HPL activity of the enzymatic extract at 80°C, in the presence of KCl, was higher by 2.78-fold than that without it. Selected chemical additives, glycine and 2-mercaptoethanol, as well as surfactant coated-enzyme (SCE) were also employed to increase the catalytic activity and stability of HPL enzymatic extract. The presence of 7% glycine or 2.5% of 2-mercaptoethanol in hexane reaction medium increased the HPL activity by 1.76- and 1.22-fold, respectively, as compared to that without additive. The modification of the enzymatic extract by its coating with Span 65, at a surfactant to protein ratio of 1:1 (w/w), resulted in 2.57-fold increase in HPL activity. The presence of 7.0% glycine or 2.5% of 2-mercaptoethnol resulted also by a higher HPL thermostability, with 3.8- and 3.5-fold, respectively, as compared to that without additive; however, the decrease in HPL thermostability was obtained with Span 65 coated-enzyme. The HPL enzymatic extract was encapsulated within alginate and hydrophobically modified alginate hydrogel, using reverse micellar system (RMS) and ternary micellar system (TMS). The dehydration, with 2-propanol, of the encapsulated enzymatic extract increased the HPL specific activity by 1.83-fold as compared to that without dehydration. Using hexane as the reaction medium, the encapsulated HPL extract in 2.0% (w/v) alginate (Alg) resulted by a 52.5% encapsulation yield and 1.37-fold higher enzyme activity than that of the free one. With ratio of 2.5 alginate to 1 of either RMS or TMS, the partition coefficient of 10-HPOD was 2.40- and 1.67-fold, respectively, higher than that of alginate alone. The HPL activity of the enzymatic extract, encapsulated in Alg:TMS (2.5:1), was enhanced by 1.42-fold, as compared to that with alginate alone; however, the inactivation of HPL activity was obtained with Alg:RMS (2.5:1). The immobilization of HPL enzymatic extract, using selected supports, and its biocatalysis in NOSM were also investigated. Dowex®50WX4-200 was found to be the most appropriated support, with an increase in HPL activity by 2.66-fold as compared to that of the free one; however, an inactivation of HPL activity was obtained with the use of Eupergit®C250L-IDA, Eupergit®C250L-EDA and Silica as supports. The chemical modification of HPL enzymatic extract with succinic anhydride, at a molar ratio of 10:1 of succinic anhydride to lysine, increased the immobilization yield by 2.21-fold, as compared to that of the untreated one. The chemical modification of HPL enzymatic extract by 14.37 to 54.98% enhanced the enzyme activity of the immobilized one by 4.28- and 3.31-fold, respectively. On the other hand, the highest HPL enzyme activity in hexane reaction medium of the free and the Dowex immobilized enzyme extracts was obtained with an initial water activity (aw) of 0.10 and 0.33, respectively. In addition, the optimum reaction temperature for the HPL activity was determined to be 55 and 45°C for the free and immobilized enzymatic extract, respectively.La stabilisation, l'immobilisation et la biocatalyse en milieux des solvants organiques (OSM) de l'extrait enzymatique de l'hydroperoxide lyase (HPL), obtenu à partie de Penicillium camemberti, ont été étudiés. Les effets des lyoprotecteurs tels que le KCl et le dextrane 1 kDa sur l'activité et la stabilité de l'HPL ont aussi été étudiés. Bien que l'activité de l'HPL a été 6,53 fois plus élevée que celle après l'ajout de KCl à la protéine enzymatique avant sa lyophilisation dans une proportion de 70 à 1 (p/p); l'ajout de la dextrine a rendu l'enzyme inactive. De plus, la stabilité thermique à 80°C de l'activité de l'HPL de l'extrait enzymatique en présence de KCl est 2,78 fois plus élevée. Des additifs chimiques sélectionnés tels que la glycine et le 2-mercaptoéthanol ainsi que des surfactants enrobant l'enzyme ont aussi été utilisées pour augmenter l'activité catalytique et la stabilité de l'HPL. L'activité de l'HPL en milieu réactionnel de l'hexane a été 1,76 et 1,22 plus élevée en présence, respectivement, de 7% de la glycine ou du 2.5% de 2-mercaptoéthanol. L'activité de l'HPL a augmentée de 2,57 fois lorsque l'extrait enzymatique a été enrobé par le Span 65 dans une proportion du surfactant à protéine de 1:1 (p/p). La stabilité thermique de l'HPL est 3,8 et 3,5 fois plus élevée en présence de 7% de la glycine et du 2.5% de 2-mercaptoéthanol, respectivement. Cependant, la stabilité thermique de l'HPL a diminué quand l'extrait enzymatique été enrobé par le Span 65. De plus, l'extrait enzymatique de l'HPL a été encapsulé dans l'alginate (Alg) et dans l'hydrogel d'alginate hydrophobiquement modifiée, en utilisant le système micellaire inversé (SMI) et le système micellaire ternaire (SMT). L'activité de l'HPL a été 1,83 fois plus élevée lorsque l'extrait enzymatique encapsulé a été déshydraté par le 2-propanol. Les résultats tendent à montrer que l'encapsulation de l'extrait enzymatique de l'HPL dans 2,0% (p/v) d'Alg a un taux d'un taux d'immobilisation de 52,5% et de1,37 fois de plus d'activité enzymatique dans l'hexane par rapport à celui non-encapsulé. En utilisant le ratio de 2,5 d'Alg à 1 SMI ou SMT, le coefficient de partage du 10-HPOD a été, respectivement, de 2,40 et de 1,67 fois plus élevé que celui réalisé dans un milieu réactionnel contenant seulement de l'Alg. L'activité de l'HPL de l'extrait enzymatique encapsulé dans un milieu réactionnel contenant Alg:TMS (2,5:1) a été 1,42 fois plus grande que celle dans celui formé seulement de l'Alg. Cependant, dans un milieu réactionnel contenant le mélange de Alg:RMS (2,5:1), l'HPL a été inactive. L'étude s'est ensuite portée sur l'immobilisation et de la biocatalyse en OSM de l'extrait enzymatique de l'HPL en utilisant des supports sélectionnés. Les résultats tendent à montrer que le Dowex®50WX4-200 a été le support le plus approprié puisque l'activité de l'HPL a été 2,66 fois plus que celle obtenue en l'absence du support. D'autre part, l'utilisation de l'Eupergit®C250L-IDA, l'Eupergit®C250L-EDA et le Silica, comme supports, a rendue l'HPL inactive. Quand l'extrait enzymatique de l'HPL a été chimiquement modifié avec une solution d'anhydride succinique et de lysine à un ratio molaire de 10:1, le taux d'immobilisation a été 2,21 fois plus grande que celui de l'extrait non-modifié. L'activité de l'HPL de l'extrait enzymatique immobilisé a été 4,28 et 3,31 fois lorsqu'il a été modifié chimiquement à 14,37 et 54,98%, respectivement. De plus, la plus grande activité enzymatique de l'HPL des extraits enzymatiques, libre et immobilisé sur le Dowex, a été obtenue en utilisant l'hexane comme le milieu réactionnel, avec une activité initiale de l'eau (aw), respectivement, de 0,10 et de 0,33. La température optimale de la réaction enzymatique de l'HPL est 55 et de 45°C pour l'extrait libre et immobilisée, respectivement.
19
De, Ranjit. „Solution properties of sodium polystyrene sulphonate in 2-ethoxyethanol-water mixed solvent media“. Thesis, University of North Bengal, 2011. http://hdl.handle.net/123456789/1435.
Der volle Inhalt der Quelle
20
Hossain, Abzal. „Immobilization of selected enriched polyphenol oxidases and their biocatalysis in organic solvent media“. Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85557.
Der volle Inhalt der QuelleAnnotation:
Polyphenol oxidase (PPO) enzymatic extracts were recovered from apple fruit and potato tubers and enriched by an acetone precipitation. The enriched PPO extracts were immobilized by adsorption onto a wide range of inorganic supports, including chitin, alumina oxide, glass beads, Celite, Dowex and Silica gel using selected media, including water, sodium phosphate buffer and a ternary micellar system. The highest immobilization efficiencies and specific activities were obtained when the PPO extracts were suspended in sodium phosphate buffer and adsorbed onto alumina oxide. Biocatalysis of the free and immobilized PPO extracts was investigated in selected organic solvent media, including hexane, heptane, toluene and dichloromethane, using chlorogenic acid, catechin, and the endogenous phenolic compounds from apple fruit and potato tubers as substrate models. In the organic solvent media, the free PPO extracts from apple and potato demonstrated optimal enzymatic activities at 28°C and between 25 to 35°C, respectively, whereas the immobilized extracts both showed optimal enzymatic activities at 30°C. The free and immobilized extracts from apple and potato also showed similar pH values for optimal enzymatic activity in the range of 6.0 to 6.5. The immobilized apple and potato PPO extracts demonstrated a 1.5 to 1.8 and 2.1 to 3.2-fold increases in PPO activity, respectively, compared to those observed with their free counterparts, and the lowest Km values were obtained with chlorogenic acid followed by catechin and the endogenous phenolic compounds. The immobilized and free PPOs from apple and potato also showed higher Vmax values in the hexane medium followed the heptane, toluene and dichloromethane media. The end products of PPO biocatalysis were purified by size-exclusion chromatography and detected at 280 nm for the residual catechin and endogenous phenolic compounds, and at 320 nm for the PPO-catalyzed end products. Spectroscopic scanning
21
Yang, Zhengnan. „Formation of Colloidal Dispersions of Polymer Materials in Aqueous Media by Solvent Shifting“. University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1399561414.
Der volle Inhalt der Quelle
22
Sinha, Biswajit. „Physico-chemical investigation on various interactions in 1,4-dioxane and its binary systems and viscous antagonism and synergism prevailing in some solvent media“. Thesis, University of North Bengal, 2007. http://hdl.handle.net/123456789/706.
Der volle Inhalt der Quelle
23
Karam, Rosalie. „Lipase-catalyzed acidolysis of fish liver oil with dihydroxyphenylacetic acid in organic solvent media“. Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18687.
Der volle Inhalt der QuelleAnnotation:
ABSTRACT M.Sc. Rosalie Karam Commercial lipases, including Lipozyme IM 20 from Rhizomucor meihei and Novozym 435 from Candida antarctica, were investigated to determine their capacity as biocatalysts for the biosynthesis of phenolic lipids, using dihydroxyphenylacetic acid (DHPA) and fish liver oil (FLO) as substrates. Novozym 435 showed a higher bioconversion yield (63%) as compared to that (18%) for Lipozyme IM 20. As a result, Novozym 435 was subsequently used for further investigations. The phenolic lipids were recovered and characterized by thin-layer chromatography, high-performance liquid chromatography and gas-liquid chromatography. The structural analyses indicated the synthesis of five major phenolic lipids. In order to optimize the initial enzymatic activity and bioconversion yield, selected parameters, including lipase amount (20 to 60 mg solid enzyme or 200 to 600 U), organic solvent ratios (hexane:2-butanone; 65:35 to 85:15, v/v), substrate molar ratios (FLO/phenolic acid, 1:1 to 8:1), Silica gel (1.5 to 5.5 mg/mL) and molecular sieve (10 mg/mL, Type 4A; 8-12 mesh), were investigated. The experimental results showed that the use of 50 mg of solid Novozym 435 (500 U) resulted in a maximum bioconversion yield of 83% of total phenolic lipids, at a molar substrate ratio 4:1. The bioconversion yield of phenolic monoacylglycerols (MAGs) increased from 11 to 70%, when the ratio of the hexane:2-butanone reaction medium was changed from 85:15 to 75:25 (v/v), respectively, whereas that of phenolic diacylglycerols (DAGs) remained relatively unchanged (13 to 16%). However, the addition of molecular sieve and Silica gel to the reaction medium resulted in a decrease in the bioconversion yield by 34% and 62%, respectively. Under the optimized conditions, the phenolic lipids showed a significant relative increase in C20:5 n-3 and C22:6 n-3 content in the phenolic MAGs and phenolic DAGs as compared to that in the unmodified FLO. The phenolic lipids demonstrated radRESUME M.Sc. Rosalie Karam Des lipases commerciales, incluant Lipozyme IM 20 de Rhizomucor meihei et Novozym 435 de Candida antarctica, ont été étudiées afin de déterminer leur efficacité comme biocatalyseur dans la biosynthèse des lipides phénoliques, en utilisant comme substrats, l´acide dihydroxyphényl acétique (ADHP) et l'huile du foie de poisson (HFP). Novozym 435 a montré un rendement de bioconversion élevé (63%) en comparant (18%) avec Lipozyme IM 20. Novozym 435 a ainsi été considéré comme un biocatalyseur approprié pour la suite du travail. Les lipides phénoliques ont été récupérés et caractérisés par chromatographie sur couche mince, chromatographie liquide à haute performance et celle liquide en phase gazeuse. Les analyses structurales ont révélé la synthèse de cinq phénoliques lipides majeurs. Afin d'optimiser l'activité enzymatique et le rendement de la bioconversion, des paramètres sélectionnés ont été étudiés, incluant la concentration en enzyme (20 à 60 mg d'enzyme solide ou 200 a 600 U), le ratio du solvant organique (hexane:2-butanone; 65:35 à 85:15, v/v), le ratio molaire des substrats (HFP/acide phénolique, 1:1 à 8:1), gel du Silice (1.5 à 5.5 mg/mL) et le tamis moléculaire (10 mg/mL, Type 4A; 8-12 mesh). Les résultats expérimentaux ont montré que l'utilisation de Novozym 435 (500 U), sous forme solide, à une concentration de 50 mg permettait d'atteindre un rendement maximal de la bioconversion des lipides phénoliques de 83% à un ratio molaire des substrats de 4 :1. Le rendement de la bioconversion de monoacylglycerols (MAGs) phénoliques a augmenté de 11 à 70%, lorsque le ratio du mélange réactionnel hexane:2-butanone a été changé de 85:15 à 75:25 (v/v), respectivement. En parallèle, le rendement de la bioconversion des diacylglycerols phénoliques (DAGs) est resté relativement constant (13 to 16%). Cependant, l'addition du tamis moléculaire ou du gel de silice dans le milieu r
24
Aziz, Sarya. „Enzymatic synthesis of phenolic lipids from krill oil in solvent-free media and their microencapsulation“. Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121162.
Der volle Inhalt der QuelleAnnotation:
The optimization of the synthesis of phenolic lipids (PLs), obtained by the enzymatic transesterification of krill oil (KO) with selected phenolic acids (PAs) in solvent-free media (SFM), as well as their separation, characterization and encapsulation were investigated. Using high-performance liquid chromatography (HPLC), the evaporative light-scattering detector (ELSD) was shown to be a more appropriate tool of detection of PLs. The structural analyses of the synthesized PLs by HPLC/mass spectrometry (MS) suggested the formation of two phenolic monoacylglycerols. Using two immobilized commercial enzymes, Novozym 435 and Lipozyme TL IM, the enzymatic synthesis of PLs from KO with two phenolic acids (PAs), including 3,4-dihydroxyphenylacetic acid (DHPA) and dihydrocaffeic acid (DHCA), was investigated. The use of Novozym 435 and DHPA resulted in the highest bioconversion yield (BY). The central composite rotatable design (CCRD) was used to evaluate the effects of PA concentration (PAC) and lipase concentration (LC) as well as the agitation speed (AS) on the BY of PLs. For the models with PAC, fixed at 10 and 20 mM, the results revealed that LC had a significant quadratic effect (P <0.05) on the BY, whereas a significant linear effect was only obtained with PAC, fixed at 20 mM. The AS had a significant quadratic effect (P <0.05) on the BY, only for the model, with a PAC fixed at 10 mM. At fixed PAC of 20 mM, the response surface model predicted a BY of 75%, using a LC of 62 mg/mL and an AS of 154 rpm. The antioxidant capacity (AOC) and the oxidative stability of PLs, obtained by the enzymatic transesterification of PAs with the selected edible oils (EOs), including flaxseed (FSO), fish liver (FO) and krill (KO) oils, were determined. The statistical analyses of Tukey's test at P <0.05 revealed that the difference in AOC between that of the esterified oils of flaxseed (EFSO) and krill (EKO) and that of EOs was significant (P <0.05). The experimental findings showed that all esterified oils containing PLs had higher oxidative stability when they were subjected to light, oxygen and agitation at 50ºC as compared to that of the EOs; nevertheless, only the esterified fish oil (EFO) showed a significant difference in its peroxide value (PV), when it was placed in the dark at 25ºC. The development of a process to yield gelatin (GE)-gum arabic (GA) multinuclear microcapsules of KO, via complex coacervation, was investigated. A three-level-by-three factor Box-Behnken design (BBD) was used to evaluate the effects of the ratio of the core material to the wall (RCW), with x1 of 1.25:1 to 1.75:1, the stirring speed (SP) with x2 of 2 to 4, over a scale of 10 and the pH with x3 of 3.8 to 4.2, on the encapsulation efficiency (EE). The experimental findings indicated that x3 had the most significant linear and quadratic effects on the EE of KO and a bilinear one with x1; however, x2 did not have any effect. The optimal predicted conditions for a 92% of EE were 1.75:1 for RCW, 3.8 for pH and 3 for SP. The microcapsules, formed by complex coacervation and without any cross-linking agent, were multinucleated, circular in shape and had sufficient stability to maintain their structure. The microencapsulation of the esterified krill oil (EKO), obtained by complex coacervation, was carried out. The experimental findings showed that the presence of DHPA and PLs, in the EKO, affected the stability of GE-EKO emulsion. The ultrasonic liquid processor was found to be a more appropriate device for the emulsification of the EKO into GE, as compared to the high-shear homogenizer. In addition, the capsules prepared with a GE at pH 8.0 showed higher storage stability, with significantly (P <0.05) lower primary oxidative products, as compared to those prepared with a GE at pH 6.5. The microencapsulation of the EKO was effective in delaying the development of primary and secondary oxidation products during a period of 25 days of storage at room temperature.L'optimisation de la synthèse de lipides phénoliques (PLs), obtenus par la transésterification enzymatique de l'huile de krill (KO) avec des acides phénoliques sélectionnés en milieu réactionnel sans solvant (SFM) ainsi que de leur séparation, caractérisation et encapsulation ont été étudiées. En utilisant la chromatographie en phase liquide (HPLC), le détecteur évaporatif à diffusion de lumière (ELSD) a été sélectionné pour les analyses des composants de KO et ses PLs estérifiés. Les analyses structurales des PLs synthétisés par HPLC/spectrométrie de masse (HPLC/MS) ont suggéré la formation de deux lipides phénoliques monoacylglycéroles. En utilisant deux enzymes commerciales immobilisées, Novozym 435 et Lipozyme TL IM et deux acides phénoliques (PA) modèles y compris l'acide 3,4-dihydroxyphénylacétique (DHPA) et l'acide dihydrocaffeique, la synthèse enzymatique des PLs à partir de KO, a été investiguée. Le meilleur rendement de bioconversion (BY) a été obtenu avec la Novozym 435 et le DHPA. Le plan composite central à caractère rotatif (CCRD) a été utilisé pour évaluer les effets de la concentration de l'acide phénolique (PAC) et de celle de la lipase (LC) ainsi que de la vitesse d'agitation (AS) sur le BY des PLs. Pour les modèles avec PAC, fixée à 10 et 20 mM, les résultats ont montré que la LC a un effet quadratique significatif (P <0,05) sur le BY, alors qu'un effet linéaire a été seulement obtenu avec PAC fixée à 20 mM. L'AS avait un effet quadratique significatif (P <0,05) sur le BY, seulement pour le modèle, avec une PAC fixée à 10 mM. Á PAC fixée à 20 mM, la surface de réponse du modèle a prédit un BY de 75%, en utilisant la LC de 62 mg/mL et la AS de 154 rpm. La capacité antioxydante (AOC) et la stabilité oxydative des PLs dans les huiles de lin (FSO), de poisson (FO) et de krill, ont été déterminées. Les analyses statistiques du test Tukey à P <0,05 ont révélé que la différence en AOC entre celle des huiles estérifiées de lin (EFSO) et de krill (EKO) et celle des blancs a été significative (P <0,05). Les résultats ont montré que tous les huiles estérifiées avec PLs avaient une stabilité oxydative plus élevée quant ils étaient exposés à la lumière et en présence de l'oxygène mais aussi soumis à l'agitation et à 50ºC comparée à celle des EOs. Le développement d'un processus pour produire des microcapsules multinucléaires, en utilisant l'association de gélatine (GE)-gomme arabique (GA) par la coacervation complexe a été investigué. Le plan Box-Behnken (BBD) à trois-niveaux-par-trois facteurs a été utilisé pour évaluer les effets du ratio huile/polymères (RCW) avec x1 de 1,25:1 à 1,75:1, la vitesse de la turbine (SP) avec x2 de 2 à 4, sur une échelle de 10 et un pH avec x3 de 3,8 à 4,2, sur l'efficience d'encapsulation (EE). Les résultats expérimentaux ont indiqué que x3 avait les effets linéaires et quadriques les plus significatifs sur la EE de KO et un effet bilinéaire avec x1; Par contre, x2 n'avait aucun effet. Les conditions optimales prédites pour une EE de 92% étaient 1,75:1 pour RCW, 3,8 pour pH et 3 pour SP. Les microcapsules, formées par la coacervation complexe et sans aucun agent d'articulation, étaient multinucléées, circulaires et assez stables pour maintenir leurs structures. La microencapsulation de l'huile de krill estérifiée par la coacervation complexe a été effectuée. Les résultats ont montré que la présence du DHPA et des PLs, dans l'EKO, avait un effet sur la stabilité de l'émulsion de GE-EKO. L'ultrason utilisé pour traitement liquide a été plus approprié pour l'émulsification de l'EKO dans GE, par rapport à l'homogénéisateur à haut débit. Les capsules préparées avec un GE à pH 8,0 ont montré une stabilité d'entreposage plus élevée avec une PV significativement (P <0,05) moins élevée que celles pour les capsules préparées avec un GE à pH 6,5. La microencapsulation de EKO a été effective pour retarder le développement de produits d'oxydation primaires et secondaires.
25
Bou, Mitri Christelle. „Stabilization and immobilization of laccase, from Coriolus hisutus, and its biocatalysis in organic solvent media“. Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119558.
Der volle Inhalt der QuelleAnnotation:
The stabilization and immobilization of laccase enzymatic extract, obtained from Coriolus hirsutus, and its biocatalysis in organic solvent media (OSM) for the synthesis of selected oligophenols, were investigated. Among the investigated lyopotectants, 2.5% mannitol was found to be the most appropriate one, where the stability of the laccase lyophilized extract was greatly enhanced, with 96.2, 38.9 and 24.7% of residual activity after 4 weeks of storage at -80, 4 and 25°C, respectively. Using syringaldazine (SG) as substrate, the free laccase showed its highest catalytic activity only in the ternary micellar system (TMS), composed of sodium acetate buffer/hexane and AOT, but not in the mono- or biphasic ones. Under the optimum conditions, the relative laccase activity in TMS was found to be 84.0% as compared to that in the aqueous medium. The results also demonstrated that 50% of the residual laccase activity was obtained after 56.8, 14.7, 8.5 and 5.0 h of incubation at 4, 25, 37 and 50ºC, respectively. The kinetic studies indicated that the Km value for laccase was 15.8, 15.8, 26.1, 44.4, 69.3, 80.5 and 330.0 µM, using sinapic acid, m-coumaric acid, ferulic acid, SG, 2,6-dimethoxyphenol, caffeic acid and 2,2ʹ-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt or ABTS, respectively, with the corresponding relative percent kcat values of 8.2, 7.0, 3.8, 1.6, 1.0, 6.8 and 0.1. Using ferulic acid (FA) as the substrate model, the optimization of laccase immobilization by physical adsorption, covalent binding and encapsulation showed that the encapsulation of the enzyme into Ca-alginate was the most appropriate approach. The highest immobilization yield of 60.9% and the residual laccase activity of 62.6% were obtained when the enzyme extract was immobilized with 1.5% (w/v) alginate and 100 mM CaCl2 at 1.5 mg/mL initial protein load. The encapsulated laccase exhibited an increase in its activity in OSM as compared to that in the aqueous one. Moreover, the encapsulated laccase was stable when it was dehydrated with iso-propanol and acetone, with 114.0 and 100.6% of residual activity, respectively; it retained 60.8 and 74.9% of its initial activity, after 24 h of its incubation at 55°C, in the aqueous and hexane medium. The encapsulated laccase also maintained 25.6 and 76.4% of its residual activity after 6 cycles of reaction in aqueous and hexane medium, respectively. The characterization of the laccase-catalyzed end products was obtained by size-exclusion chromatography (SEC), high-performance liquid chromatography (HPLC), spectrophotometric, Fourier-transform infrared spectroscopy (FTIR), pyrolysis/gas liquid chromatography/mass spectrometry (Py/GC/MS) and mass spectrometry (MS) analyses. The results showed that the biocatalysis of laccase in aqueous medium resulted in the synthesis of three end products, identified as di-, tri- and tetramer of FA with a molecular weight (MW) of 386.4, 578.5 and 770.7 Da, respectively; however, only the dimers of FA were obtained in OSM, with a MW of 386.4 Da. The FTIR and MS analyses indicated that the polymerization of FA involved the C-O coupling modes in the aqueous medium. The pyrograms showed that the dimers, obtained in OSM, were more stable than all the end products obtained in the aqueous medium. The dimers, obtained in the OSM, demonstrated also the highest oxygen-radical absorbance capacity (ORAC) value, with 2.7 and 14.5-fold higher than that for FA and for its dimers, obtained in the aqueous medium, respectively.La stabilité et l'immobilisation de l'extrait enzymatique contenant la laccase, obtenu de Coriolus hirsutus, et sa biocatalyse dans un milieu réactionnel de solvants organiques (OSM) pour la synthèse des oligophenols sélectionnés, ont été étudiés. Parmi les différents lyoprotectants utilisés, 2.5% mannitol a été jugée le plus approprié, où la stabilité de l'extrait lyophilisé de la laccase a été énormément amélioré, avec 96,2, 38,9 et 24,7% d'activité résiduelle après 4 semaines d'entroposage à -80, 4 et 25°C, respectivement. En utilisant la syringaldazine (SG) comme substrat modèle, la laccase a seulement montré une activité catalytique dans le milieu micellaire ternaire, composé du tampon d'acétate de sodium/ hexane et l'AOT, mais pas dans les milieux mono- ou bi-phasiques. Sous les conditions optimales, l'activité de la laccase dans le milieu micellaire ternaire a été de 84,0% relativement à celle obtenu dans le milieu aqueux. Les résultats ont également démontré que dans le milieu micellaire ternaire 50% de l'activité résiduelle de la laccase a été obtenu après 56,8, 14,7, 8.5 and 5,0 h d'incubation à 4, 25, 37 et 50ºC, respectivement. Les études cinétiques ont indiqué que la valeur de Km pour la laccase a été de 15,8, 15,8, 26,1, 44,4, 69,3, 80,5 et 330.0 µM, en utilisant l'acide sinapique, l'acide m-coumarique, l'acide férulique, la SG, le 2,6-dimethoxyphenol, l'acide cafféique et le sel diammonium 2,2`-azino-bis(3-ethylbenzothiazoline-6-sulfonic acide) ou l'ABTS, respectivement, avec les valeurs correspondantes relatives de kcat de 8,2, 7,0, 3,8, 1,6, 1,0, 6,8 et 0,1. L'utilisation de l'acide férulique (FA) comme substrat modèle, l'optimisation de l'immobilisation de la laccase par adsorption physique, liaison covalente et encapsulation a démontré que l'approche la plus appropriée était l'encapsulation de l'enzyme avec l'alginate de calcium. Le rendement d'immobilisation (60,9%) et l'activité résiduelle (62,6%) les plus élevés ont été obtenue lorsque l'extrait enzymatique a été immobilisé avec 1,5% (p/v) d'alginate, 100 mM CaCl2 et 1,5 mg/mL de quantité initiale de protéine. La laccase encapsulée présente une augmentation de son activité dans l'OSM par rapport à celle dans le milieu aqueux. En outre, la laccase encapsulée présente une haute stabilité quand elle est déshydratée avec de l'iso-propanol et l'acétone, en conservant 114,0 et 100,6% de son activité, respectivement. De plus, elle a retenu 60,8 et 74,9% de son activité initiale, après 24 h d'incubation à 55°C, dans le milieu aqueux et l'hexane. Également, la laccase encapsulée a maintenu 25,6 et 76,4% de son activité initial après 6 cycles de réaction en milieux aqueux et l'hexane, respectivement. La caractérisation des produits finaux obtenus par l'oxydation du FA par la laccase a été faite par des analyses de chromatographie d'exclusion stérique (SEC), chromatographie en phase liquide a haute performance (HPLC), spectrophotométrie, spectroscopie infrarouge a transformée de Fourier (FTIR), la pyrolyse couplée à la chromatographie en phase gazeuse et la spectrométrie de masse (Py/GC/MS), la chromatographie liquide ainsi que par spectrométrie de mass (MS). Les résultats ont montré que la biocatalyse de la laccase dans un milieu aqueux, mène à la synthèse de produits finaux différents identifiés comme des di-, tri- et tétramère du FA avec des poids moléculaires (MW) de 386,4; 578,5 et 770,7 Da, alors que dans le OSM, seuls des dimères du FA de PM 386.4, ont été obtenu. L'analyse de FTIR ainsi que ceux du MS ont démontré que la polymérisation du FA dans le milieu aqueux implique les modes de couplage C-O. Les pyrogrammes ont démontré que les dimères, obtenus dans l'OSM sont plus stables que les ceux obtenus dans le milieu aqueux. Les dimères, obtenus dans l'OSM, ont démontré une capacité d'absorption des radicaux oxygénés (ORAC) avec des valeurs de 2,7 et 14,5 fois plus élevées que ceux du FA et les dimères obtenus dans le milieu aqueux, respectivement.
26
ZHANG, WENWEN. „Catalytic Conversion of Sugar Mixtures into Furan Products in Ionic Liquid Media with Organic Solvent Extraction“. University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1341540235.
Der volle Inhalt der Quelle
27
Banik, Ishani. „Physico-Chemical studies on interaction of biologically active solutes and ionic salts in some industrially important solvent media“. Thesis, University of North Bengal, 2014. http://ir.nbu.ac.in/handle/123456789/1491.
Der volle Inhalt der Quelle
28
Sarma, D. „Effect of solvent media in altering the rates of diels-alder reactions and other C-C bond forming reactions“. Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2007. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2545.
Der volle Inhalt der Quelle
29
Mahi, Mohammed Ridha. „Captage du CO2 par des amines en milieu aqueux et non aqueux (solvant eutectique profond)“. Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1104.
Der volle Inhalt der QuelleAnnotation:
Ce travail porte sur l'étude de la capacité d'absorption du CO2 par différents types d'amines dissoutes en milieux aqueux et non aqueux. Ce dernier est constitué d'un mélange de chlorure de choline et d'éthylène glycol dans une proportion molaire respectivement de 1 pour 2. Ce solvant, communément appelé "Ethaline", appartient à la catégorie dite des « Solvants à Eutectique Profond » ainsi désignés car leur composition eutectique permet d'obtenir des mélanges généralement liquides à température ambiante. Pour ce faire un appareil d'équilibre liquide-vapeur avec analyse en ligne de la phase vapeur par GC a été réalisé et son fonctionnement validé. Les isothermes d'absorption du CO2 ainsi que la volatilité (composition de la phase vapeur) des mélanges étudiés, avec et sans CO2, ont été déterminées à différentes températures et pour différentes compositions en amines. Le domaine de pression exploré est particulièrement large : du Pascal à 800 kPa. L'étude a montré que la substitution de l'eau par "l'Ethaline" conduit à une capacité d'absorption du CO2 presque identique à celle de la MEA et DEA en solution aqueuse. Par contre dans le cas de la MDEA on observe une capacité d'absorption plus faible en milieu « Ethaline » qu'en milieu aqueux. Les isothermes d'absorption du CO2 des trois classes d'amines en milieu aqueux et non aqueux ont été corrélés par les modèles semi empiriques de (Gabrielsen et al., 2005) initialement établis par ces auteurs pour les solutions aqueuses (un modèle pour les amines primaires et secondaires conduisant à la formation de carbamates en présence de CO2, un modèle pour les amines tertiaires donnant des sels d'ammonium avec le CO2). Nous avons montré que ces deux modèles représentent avec succès les isothermes d'absorption en milieu non aqueux. Les constantes d'équilibre et les enthalpies de réaction qui s'en déduisent montrent que ces dernières sont plus faibles (en valeur absolue) pour la MEA et TMDEA en solution éthaline qu'en solution aqueuse. Dans le cas de la MDEA la nature du solvant n'a qu'une influence minime sur l'enthalpie de réaction. Les valeurs expérimentales des volatilités des amines dans les différents mélanges Amine- CO2 en milieu aqueux ont été corrélées par différents modèles semi-empiriques. Trois modèles thermodynamiques de coefficients d'activité ; le modèle de Wilson, NRTL et UNIQUAC ont été utilisés afin de restituer les données expérimentales de l'équilibre liquide-vapeur des systèmes aqueux d'amines (sans CO2). Une représentation satisfaisante des résultats expérimentaux par les trois modèles a été obtenueThis work focuses on the study of the absorption capacity of CO2 by different types of dissolved amines in aqueous and non-aqueous media. The latter consists of a mixture of choline chloride and ethylene glycol in a molar proportion of 1 to 2 respectively. This solvent, commonly called "Ethaline", belongs to the category called "Deep Eutectic Solvents" so designated because their eutectic composition makes it possible to obtain mixtures that are generally liquid at room temperature. With this aim, a liquid-vapor equilibrium apparatus with on-line analysis of the vapor phase by GC was performed and its operation validated. The CO2 absorption isotherms and the volatility (composition of the vapor phase) of the studied mixtures, with and without CO2, were determined at different temperatures and for different amine compositions. The explored pressure range is particularly large: from 1 Pa to 800 kPa. The study showed that the substitution of water by "Ethaline" leads to a CO2 absorption capacity almost identical to that of MEA and DEA in aqueous solution. On the other hand, in the case of MDEA, a lower absorption capacity is observed in Ethaline than in aqueous medium. In the hypothesis of a use of the DES+amine solvent for CO2 capture in post-combustion process, a decrease of the vapor pressure of the solvent (comparing to that of water+amine) has an advantage because of the low solvent loss due to vaporization in the absorber. The second advantage is most likely a lower effect of equipment corrosion, the third positive point is a lower enthalpy of absorption of MEA and MDEA in (1 ChCl : 2 EG) comparing to aqueous medium, resulting in a possible saving of energy in the regenerator of almost 40%. The disadvantage of the use of amines in "Ethaline" solution is the high viscosity of this solvent which decreases the kinetics of material transfer and reaction with CO2. The CO2 absorption isotherms and the experimental values of the amine volatilities in the different Amine-H2O-CO2 mixtures were well correlated by different semi-empirical models. Three thermodynamic models based on the activity coefficients; the Wilson model, NRTL and UNIQUAC were used to restitute experimental data for the liquid-vapor equilibrium of aqueous amine systems (without CO2). A satisfactory representation of the experimental results by the three models was obtained
30
Leang, Marguerite. „Pénétration d'un solvant dans un gel poreux en consolidation : application à la restauration des oeuvres d'art“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS469/document.
Der volle Inhalt der QuelleAnnotation:
La restauration des peintures d'art consiste à restaurer la lisibilité d'une œuvre d'art et à préserver son intégrité. La plupart des techniques consiste à déposer des solvants juste en surface afin de ne dissoudre que la couche de vernis. Cependant, les couches sous-jacentes risquent d'être endommagées par la pénétration de ces solvants, causant éventuellement un gonflement ou un craquèlement de ces dernières. Du fait de la complexité physico- chimique de la couche picturale, nous proposons d'étudier la pénétration de solvants dans un nanoporeux modèle issu du séchage contrôlé de dispersions aqueuses de nanoparticules de silice. Le séchage et la consolidation de ces dispersions colloïdales jusqu'à l'apparition de craquelures de séchage sont étudiés. La réflectivité de neutrons et la diffusion de neutrons aux petits angles permettent d'accéder à la structuration des systèmes en surface et en volume, respectivement, au cours du séchage. L’étude expérimentale des ouvertures de craquelures dues au séchage, associée à un modèle de poroélasticité que nous développons, renseigne sur les propriétés mécaniques des systèmes consolidés et du tableau « Jeanne d'Arc en prison » (1824) du peintre français Louis Crignier (1790-1824). La caractérisation du milieu poreux formé après la consolidation est réalisée par imagerie de neutrons et permet de déterminer la perméabilité et les porosités des milieux. Enfin, nous présentons la dynamique d'imprégnation d'une goutte sessile de solvant dans plusieurs milieux poreux, qui diffèrent de par leur taille de pores. Notre montage expérimental permet une quantification précise et directe des écoulements au-dessus et à l'intérieur du milieu poreux. Des mesures de propriétés mécaniques sont réalisées avant et après imprégnation par micro-indentationArt painting restoration aims to restore the readability of a painting and to preserve its integrity. Most of the techniques consist of depositing solvents on the surface of the painting to dissolve the varnish layer. However, the sublayers can be damaged by the penetration of the solvent, possibly resulting in swelling or cracking processes. Due to the physical and chemical complexity of the pictorial layer, we propose to study solvent penetration in model nano porous media obtained by controlled drying of aqueous silica nanoparticles dispersions. Drying and the consolidation process of these colloidal dispersions are studied until drying cracks appear. Neutron reflectivity and small angle neutron scattering provide structural information on particles near the interface between the dispersion and the air and in the bulk, respectively, during drying. The experimental study of drying cracks, associated to a poroelastic model, inform on mechanical properties of consolidated model systems and of the painting “Jeanne d'Arc en prison” (1824) by the French painter Louis Crignier (1790-1824). Characterization of the porous media obtained after consolidation is carried out with neutron imaging to determine the permeability and the porosities of the porous media. Finally, we present the dynamics of imbibition of sessile solvent drops on several porous media with different pore sizes. Our experimental set-up provides a precise and a direct quantification of the different flows outside and through the porous media. Mechanical properties are performed before and after solvent imbibition, by micro-indentation testing
31
Tran, Van Duy. „Prise en compte du caractère discontinu du solvant dans la modélisation mécanique des argiles gonflantes“. Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0036/document.
Der volle Inhalt der QuelleAnnotation:
Ce travail vise à améliorer la description à l'échelle du nanomètre des sols argileux expansifs en utilisant la théorie de la fonctionnelle de densité (DFT). L’eau n’est plus considérée comme un solvant continu mais comme un fluide de molécules polaires individuelles. L'objectif est de reproduire les résultats issus de l'expérience ou de la modélisation numérique tels que la présence de couches d'eau discrètes dans l'espace interfolaire ou la variation de la pression de disjonction avec la distance interfolaire dans le régime de gonflement cristallin. Différents phénomènes physiques de complexité croissante sont successivement étudiés. La taille finie des molécules d'eau est tout d'abord prise en compte en modélisant l'eau comme un fluide de sphères dures traité par la théorie fondamentale de la mesure. La nature polaire du solvant est ensuite implicitement considérée en utilisant un potentiel intermoléculaire de Lennard-Jones pour reproduire les différents types d'interactions de Van der Waals. La nature dipolaire de l'eau est ensuite explicitement modélisée par un fluide dipolaire de sphères dures. Ces deux derniers modèles utilisent une approche perturbative de la théorie de la fonctionnelle de densité dans laquelle les effets de corrélation entre les molécules du fluide sont incorporés. Les ions sont finalement ajoutés afin de compléter la description de la double couche électrique. En vue d'une application au génie civil, l'expression améliorée de la pression de disjonction à l'échelle nanométrique est incluse dans une forme modifiée du principe de Terzaghi appliqué aux argiles expansives non-saturées récemment développée dans notre groupe afin de simuler numériquement le comportement hydro-mécanique des argiles gonflantes lors d’essais d'infiltration d’eauThis work aims at improving the nanoscale description of expansive clayey soils using the Density Functional Theory (DFT). Water is no longer considered as a continuous solvent but as a fluid of individual polar molecules in order to recover existing experimental and modeling results such as the presence of discrete water layers in the interplatelet space or the variation of the disjoining pressure with the interplatelet distance at low hydration level. Different physical phenomena of increasing complexity are successively considered. The finite size of the water molecules is firstly taken into account by modeling water as a Hard Sphere fluid using the Fundamental Measure Theory. The polar nature of the water solvent is then implicitly taken into account through a Lennard-Jones potential averaging the different types of Van der Waals interactions. Next the polar nature of the solvent is explicitly modelized by considering water as a Dipolar Hard Sphere fluid. These two fluid models are studied in the framework of the Density Functional Perturbation Theory in which correlation effects between the fluid molecules are incorporated. Ions are finally added in order to complete the Electrical Double Layer description at the nanoscale. With the objective of an application to civil engineering, the improved expression of the disjoining pressure at the nanoscale is included in a modified form of Terzaghi's effective stress principle for unsaturated expansive clays recently developed by our group in order to numerically simulate the hydro-mechanical behavior of expansive clays during water uptake
32
Braybrook, David Robert. „Studies of cytochromes P450â†CAM in non-aqueous media“. Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386896.
Der volle Inhalt der Quelle
33
Boving, Thomas Bernhard. „Performance and simulation of chemically enhanced solubilization and removal of residual chlorinated solvents from porous media“. Diss., The University of Arizona, 1999. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1999_154_sip1_w.pdf&type=application/pdf.
Der volle Inhalt der Quelle
34
Donderici, Burkay. „Time-Domain Solvers for Complex-Media Electrodynamics and Plasma Physics“. The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1216744283.
Der volle Inhalt der Quelle
35
Paul, Chowdhury Madhurima. „Physicochemical studies on double-chain amphiphiles and their aggregation behavior in different media“. Thesis, University of North Bengal, 2018. http://ir.nbu.ac.in/handle/123456789/2692.
Der volle Inhalt der Quelle
36
Pätzold, Magdalena [Verfasser]. „Evaluation of deep eutectic solvents as alternative reaction media in biocatalysis / Magdalena Pätzold“. Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2020. http://d-nb.info/1222589087/34.
Der volle Inhalt der Quelle
37
SOARES, PAULO S. M. „Estudo preliminar do fracionamento de terras raras medias e pesadas em grupos com extracao por solventes“. reponame:Repositório Institucional do IPEN, 1994. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10353.
Der volle Inhalt der QuelleAnnotation:
Made available in DSpace on 2014-10-09T12:37:40Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:00:21Z (GMT). No. of bitstreams: 1 05345.pdf: 9869797 bytes, checksum: 233848268ca6b451d04e82fb4874216e (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
38
Greenberg, Jeffrey H. Nezu Christine M. „Televised news media exposure, fear of terrorism, and social problem-solving /“. Philadelphia, Pa. : Drexel University, 2006. http://hdl.handle.net/1860/1242.
Der volle Inhalt der Quelle
39
Kemshal-Bell, Guy Jonathon, und guykb@bigpond net au. „Interactive media - a tool to enhance human communication“. RMIT University. Creative Media, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080102.100544.
Der volle Inhalt der QuelleAnnotation:
This exegesis investigates the use of interactive online media to support the development of communication and problem solving skills amongst learners in a Vocational Education and Training (VET) context. It describes the development of the Maelstrom website as a response to the identified need for a collaborative, interactive online space where learners can explore and experiment within the safe and anonymous environment provided. The user interaction within the Maelstrom and user responses to their experiences are discussed and analysed to not only inform the role of the Maelstrom within the broader context on interactive online communication and collaboration, but also to guide future research.
40
Rivière, Béatrice. „Discontinuous Galerkin methods for solving the miscible displacement problem in porous media /“. Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Der volle Inhalt der Quelle
41
Medina, Oliva Angel Francisco [Verfasser]. „Formation of DNA complexes in aqueous and organic solvents / Angel Francisco Medina Oliva“. Mainz : Universitätsbibliothek Mainz, 2012. http://d-nb.info/102599566X/34.
Der volle Inhalt der Quelle
42
Söldner, Anika [Verfasser], und Burkhard [Akademischer Betreuer] König. „Deep Eutectic Solvents as Extraction, Reaction and Detection Media for Inorganic Compounds / Anika Söldner ; Betreuer: Burkhard König“. Regensburg : Universitätsbibliothek Regensburg, 2020. http://d-nb.info/1210728869/34.
Der volle Inhalt der Quelle
43
Rees, Ian. „Development of an edge-based finite volume solver for porous media flow applications“. Thesis, Swansea University, 2004. https://cronfa.swan.ac.uk/Record/cronfa43012.
Der volle Inhalt der QuelleAnnotation:
The work presented in this thesis constitutes the first phase in the development of a solver in handle the highly non-linear systems that describe the flow of fluids through porous media. Aspects researched are the mathematical description, discretization as well as the computer code implementations. With regards to the spatial discretization a computational efficient edge-based vertex-centred finite volume scheme is proposed, with the application of a ‘compact stencil’ to calculate second derivative terms. With regards to the software implementation, a novel label based approach was employed using FORTRAN that greatly improved the flexibility of the code. The modelling capabilities of the proposed numerical scheme were validated successfully through the simulation of problems for which benchmark numerical solutions or analytic solutions exist.
44
Parmar, Manish M. „Polymorph selection with morphology control using solvents and additives“. Thesis, Liverpool John Moores University, 2016. http://researchonline.ljmu.ac.uk/4399/.
Der volle Inhalt der QuelleAnnotation:
Sulphathiazole is a highly polymorphic model system exhibiting at least five polymorphic forms: I, II, III, IV, and V. Polymorph stability is known to be susceptible to solvent environment, and it is established that 1-propanol stabilizes the most metastable form I. This study examines the effect of a range of alcohols on polymorph selection and attempts to elucidate the mechanism. The role of the alcohol functional group in the polymorph selection process is thus investigated and evaluated. Crystals were characterized using optical microscopy, SEM, PXRD, DSC, IR, and single-crystal X-ray diffraction for their polymorphic identity. The role of solvent in the stabilization of polymorphs was investigated by visualizing and calculating energy requirements for the interaction of each solvent molecule with α- and β-dimers of sulphathiazole, using Cerius2 modeling software and GRID based systematic search simulation. These studies showed that solvent had a significant impact on polymorph selection. In common with 1-propanol, 1-butanol was found to stabilize form I by inhibiting the formation of the β-dimer, which is necessary for nucleation of and transformation to forms II-IV. Shorter chain alcohols and branched chain alcohols such as methanol, 2-propanol, and ethanol did not stabilize form I but stabilized forms II, III, and IV, respectively, showing that it is not only the alcohol functionality but also the steric effects of the alkyl chain that contributed to the effect. Sulphathiazole form I normally has a needlelike morphology. Form I with a modified rodlike morphology was produced by crystallization from 1-propanol with the addition of methanol in low concentration, showing that it is possible to control the morphology and selectively isolate polymorphs. Indomethacin is known to exhibit at least five polymorphs but only the stable γ Form and metastable α Form are reported to be reliably produced by standard methods. The metastable α Form has an undesirable fibrous needle-like morphology. The current study focused on producing crystals of α Indomethacin with a well-defined morphology using additives. Adipic acid, myristic acid, oleic acid and structurally related 3-indoleacetic acid were selected as additives and their impact on the morphology and polymorphism of indomethacin were investigated in this study. Additives did not change the needle-like morphology of α-indomethacin but less fibrous and less aggregated well defined needles were observed in presence of adipic acid, oleic acid and 3-indole-3-acetic acid.
45
Brogdon, Brian N. „Effects of ethanol media on chlorine dioxide and extraction stages for kraft pulp bleaching“. Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/7014.
Der volle Inhalt der Quelle
46
Calder, Nigel Stuart. „Processing mathematical thinking through digital pedagogical media the spreadsheet /“. The University of Waikato, 2008. http://hdl.handle.net/10289/2662.
Der volle Inhalt der QuelleAnnotation:
Abstract This study is concerned with the ways mathematical understanding emerges when mathematical phenomena are encountered through digital pedagogical media, the spreadsheet, in particular. Central to this, was an examination of the affordances digital technologies offer, and how the affordances associated with investigating mathematical tasks in the spreadsheet environment, shaped the learning trajectories of the participants. Two categories of participating students were involved, ten-year-old primary school pupils, and pre-service teachers. An eclectic approach to data collection, including qualitative and quantitative methods, was initially undertaken, but as my research perspective evolved, a moderate hermeneutic frame emerged as the most productive way in which to examine the research questions. A hermeneutic process transformed the research methodology, as well as the manner in which the data were interpreted. The initial analysis and evolving methodology not only informed this transition to a moderate hermeneutic lens, they were constitutive of the ongoing research perspectives and their associated interpretations. The data, and some that was subsequently collected, were then reconsidered from this modified position. The findings indicated that engaging mathematical tasks through the pedagogical medium of the spreadsheet, influenced the nature of the investigative process in particular ways. As a consequence, the interpretations of the interactions, and the understandings this evoked, also differed. The students created and made connections between alternative models of the situations, while the visual, tabular structuring of the environment, in conjunction with its propensity to instantly manage large amounts of output accurately, facilitated their observation of patterns. They frequently investigated the visual nature of these patterns, and used visual referents in their interpretations and explanations. It also allowed them to pose and test their informal conjectures and generalisations in non-threatening circumstances, to reset investigative sub-goals easily, hence fostering risk taking in their approach. At times, the learning trajectory evolved in unexpected ways, and the data illustrated various alternative ways in which unexpected, visual output stimulated discussion and extended the boundaries of, or reorganised, their interaction and mathematical thinking. An examination of the visual perturbations, and other elements of learning as hermeneutic processes also revealed alternative understandings and explanations. Viewing the data and the research process through hermeneutic filters enhanced the connectivity between the emergence of individual mathematical understanding, and the cultural formation of mathematics. It permitted consideration of the ways this process influences the evolution of mathematics education research. While interpretive approaches are inevitably imbued with the researcher perspective in the analysis of what gets noticed, the research gave fresh insights into the ways learning emerges through digital pedagogical media, and the potential of this engagement to change the nature of mathematics education.
47
Galluzzo, Benjamin Jason. „A finite-difference based approach to solving the subsurface fluid flow equation in heterogeneous media“. Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/966.
Der volle Inhalt der QuelleAnnotation:
In this thesis, we examine the equation describing fluid flow through saturated porous medium in order to develop a new method for approximating hydraulic head values in the subsurface. In particular, we show that under reasonable assumptions, the local explicit equation (LEE) method, an accurate, finite-difference based method that is highly sensitive to changes in the assumed location of hydraulic flow parameters, can be used to approximate hydraulic head values throughout a subsurface domain of interest. This forward solution of the fluid flow equation is solved using an altered finite difference scheme, designed to account for discontinuous jumps often encountered between subsurface material types. While the method is able to handle complicated discontinuities arising from the intermingling of various underground materials, the method determines values at nodes on an easy-to-use uniform Cartesian grid and only requires information from immediately adjacent points. The results of this research directly support the development of more accurate subsurface fluid flow models for use in a wide variety of real-world situations in areas such as water management, contaminant remediation and waste storage. Furthermore, the general development of the LEE method allows it to be used as an approximation technique for any equation where the media of interest encounters a jump.
48
Markovic, Angie. „An investigation of sparse matrix solvers with applications to models of transport in porous media“. Thesis, Queensland University of Technology, 1995. https://eprints.qut.edu.au/37194/1/37194_Markovic_1995.pdf.
Der volle Inhalt der QuelleAnnotation:
This thesis investigates several forms of conjugate gradient solvers, including generalized techniques for application to non-symmetric matrix systems. To increase
the robustness and convergence rates of these solvers, various point and block form preconditioners are applied and tested. The numerical simulation of the convective drying of timber is chosen as the representative problem for analysing the performance of these iterative solvers.
A control volume formulation of the three partial differential equations describing the timber drying process is adopted. These equations are strongly coupled,
highly non-linear and anistropic. These characteristics make the partial differential
equations difficult to solve and the matrix systems arising are in general large and sparse. Thus, the system requires considerable computational effort to solve
using traditional solution techniques. The techniques described in this work seek to reduce this computation effort and streamline what is typically the most time
consuming part of numerical simulations of this type.
This work identifies the optimal conjugate gradient solver for the test problem chosen. Additionally, the preconditioner which produced the most noticeable
increase in the robustness and convergence of the iterative solvers is established. Recommendations for future work to identify options for improving the overall
processing times and the robustness of the iterative schemes are presented.
49
Ahmed, Ejaz, Joachim Breternitz, Matthias Friedrich Groh und Michael Ruck. „Ionic liquids as crystallisation media for inorganic materials“. Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138932.
Der volle Inhalt der QuelleAnnotation:
Ionic liquids (ILs) have made a great impact on materials science and are being explored for potential applications in several disciplines. In this article, we briefly highlight the current state-of-the-art techniques employing ILs as new crystallisation media, working as neutral solvent, template or charge compensating species. The use of an IL as environmental friendly solvent offers many advantages over traditional crystallisation methods. The change from molecular to ionic reaction media leads to new types of materials being accessible. Room temperature ILs have been found to be excellent solvent systems for the crystallisation of a wide range of substances and morphologies ranging from nanoscopic crystals to micro- and even to macroscopic crystals. Moreover, high temperature routes, such as crystallisation from melts or gas phase deposition, have been replaced by convenient room or low temperature syntheses, employing ILs as reaction mediaDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
50
Samadi, Dinani Mahnoush. „Scalable Heuristics for Solving the p-median Problem on Real Road Networks“. Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1543837653046322.
Der volle Inhalt der Quelle