Dissertations / Theses on the topic 'Chemical Enhancement'
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Grewal, Burrinder S. "Mechanisms of chemical and physical transdermal penetration enhancement." Thesis, Aston University, 1999. http://publications.aston.ac.uk/10978/.
Full textVeilleux, Jocelyn. "The hydrodynamics of mass diffusion enhancement in nanofluids." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97103.
Full textLa diffusion massique dans les nanofluides est étudiée par l'entremise de la microscopie en fluorescence par réflexion totale interne (ci-après nommée microscopie TIRF, pour Total Internal Reflection Fluorescence) et de modélisation physique. En particulier, le design d'un microscope TIRF ainsi que les algorithmes de traitement d'images spécifiquement destinés à la mesure du coefficient de diffusion d'un colorant fluorescent dans les nanofluides sont présentés.La microscopie TIRF et les algorithmes de traitement d'images sont d'abord employés pour déterminer le coefficient de diffusion de la rhodamine 6G (R6G) dans l'eau déminéralisée. Le coefficient moyen obtenu, à savoir D = 3,3E-10 mètre carré par seconde, confirme à la fois la justesse et la précision de la méthode de mesure proposée, comparativement aux techniques établies.L'emploi d'une membrane poreuse hydrophile lors de l'injection de la solution de R6G permet de retarder l'apparition et de réduire les conséquences des effets de la flottabilité solutale sur les mesures de diffusivité dans un canal aux dimensions millimétriques.Ensuite, cette méthode de microscopie TIRF est utilisée pour mesurer le coefficient de diffusion de la R6G dans des suspensions de nanoparticules d'alumine dans l'eau, pour différentes fractions volumiques (0,1 à 4,0%). Les résultats montrent que la diffusion massique est améliorée par un facteur 10 pour un nanofluide contenant 2 vol% de nanoparticules, comparativement à la valeur obtenue dans l'eau déminéralisée.Enfin, un modèle de dispersion induite par mouvement brownien est développé pour expliquer l'amélioration de la diffusion massique. Il s'avère que le mouvement brownien des nanoparticules est suffisant pour induire une perturbation dans le fluide environnant et ainsi créer un profil de vitesse qui sera à l'origine de la dispersion. Ce profil de vitesse s'apparente à la solution aux équations de Brinkman et permet de tirer une analogie entre les nanofluides et les lits de particules fixes pour établir le modèle de dispersion. Les prédictions du modèle concordent avec l'ordre de grandeur du coefficient de diffusion mesuré.
Johnson, Mark E. "Biophysical aspects of transdermal drug delivery and chemical enhancement." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10912.
Full textLing, Juliette Roseanne. "Enhancement of the interfacial transfer of iodine by chemical reaction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29382.pdf.
Full textNadgouda, Sourabh Gangadhar. "Syngas and Hydrogen Production Enhancement Strategies in Chemical Looping Systems." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1564740683265567.
Full textPham, Vu Anh. "Surface modifying macromolecules for enhancement of polyethersulfone pervaporation membrane performance." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/9817.
Full textMcCleave, Robert W. (Robert William). "Impinging jet heat transfer with turbulence enhancement at the nozzle." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=68045.
Full textAverage turbulence intensity of the jet flow was characterised by integrating the local turbulence intensity values over the width of the nozzle and at several axial positions from the nozzle exit to the near approach to the impingement surface. Average impingement heat transfer was obtained by integrating the local Nusselt number over an area of the impingement surface relevant to the process engineering application of impingement drying of paper.
Of the several simple methods of turbulence generation examined, the most effective was the simple expedient of placing a bar with a diameter 1/8 that of the nozzle width along the centreline of the slot nozzle. For a heat transfer averaging area equivalent to a nozzle area of 5% of the impingement surface and a nozzle to impingement surface spacing of 1.0 to 1.5 times the nozzle width, this simple method increased average heat transfer rates over those of the plain nozzle by 14%, with only a 7% increase in nozzle operating pressure. The results are presented as enhancement in average heat transfer as a graphical function of mean turbulence intensity, and as an empirical correlation between mean Nusselt number, mean intensity of turbulence and Reynolds number.
Krishnan, Gayathri. "Skin penetration enhancement techniques." Thesis, Curtin University, 2011. http://hdl.handle.net/20.500.11937/1471.
Full textWagger, David Leonard 1963. "Turbulent flow enhancement by polyelectrolyte additives : mechanistic implications for drag reduction." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13125.
Full textAnantawaraskul, Siripon. "Heat transfer enhancement under a turbulent impinging slot jet." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33321.
Full textThe impingement heat transfer rate was observed to increase due to internal finning of the slot nozzles. Both rectangular and triangular fins were tested. The fins acted as roughness elements. Experimental results with the "rough" nozzle show that the stagnation and average heat transfer rates can be enhanced by up to 15% and 10%, respectively. However, an increase in pressure drop across the nozzles is also noted.
Use of inclined confinement surfaces of 10° and 20° angles accelerate the exit flow provides average impingement heat transfer rates comparable with those for parallel wall confinement. Experimental results show no significant change in the heat transfer distribution for the inclination angle of 10°, while the average heat transfer coefficient is in fact decreased slightly for the inclination angle of 20° at high jet Reynolds numbers.
It was found that insertion of a single turbulence generator in the jet flow provides superior impingement heat transfer without any increase in the system pressure drop. Two types of turbulence generators (square rod and thin plate) were investigated. Both turbulence generators provide the same level of average heat transfer enhancement (up to 15%).
Gullick, Darren R. "The enhancement of percutaneous absorption by chemical modification of therapeutic agents." Thesis, University of Portsmouth, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494435.
Full textKeller, Klaus 1966. "Chemical enhancement of carbon dioxide transfer across the air-sea interface." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35997.
Full textLeung, Ricky. "Enhancement of oxygen transfer rate using microencapsulated silicone oils as oxygen carriers." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56795.
Full textBotes, Jacobus Petrus. "Flux enhancement using flow destabilization in capillary membrane ultrafiltration." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51763.
Full textENGLISH ABSTRACT: The aim of the thesis was to investigate the use of flow destabilization methods, combined with permeate backflushing (BIF) or on their own, on flux recovery and maintenance in capillary UF membrane systems under cross-flow (XF) and dead-end (DE) operating conditions. Various hydraulic and mechanical methods have been used to remove the accumulated cake layer and improve steady state process flux. Permeate backflushing (B/F) is the most widely used but the drawbacks are loss of product and extensive down-time. In a pilot plant study for ultrafiltration of surface waters containing high NOM, turbidity and cation loads, the use of flow destabilization, or feed flow reversal (FFR) combined with cross-flow B/F was able to improve the normalised flux by 10.7 ± 3.4 %, compared with 3.2 ± 1.6 % improvement for BIF without FFR. When a second B/F included FFR, the flux improvement was 7.0 ± 2.0 % compared with 4.3 ± 2.5 % for a B/F without FFR. The hypothesis was proposed that the flow destabilization caused slight lifting of the oriented cake layer, while the cross-flow B/F was able to sweep the lifted cake out of the lumen. If the flow destabilization may be effected by a simple but effective and low-cost method, and if this flow destabilization may be combined with reverse flow for short durations, the "lift-and-sweep" approach will be the ideal method of maintaining process flux and increasing membrane life. Such a flow destabilization method, now named "reversepressure pulsing" (RIP), was developed. The method involves circulation of feed water in a recycle loop for 2 s to gain momentum, followed by closure of a fast-action valve upstream of the modules. The momentum of the water in the concentrate loop carries it into an air-filled feed accumulator, while concentrate and reverse-flow permeate (which also lifts the fouling layer) are discharged to the atmosphere using the recycle pump for 15 s. When the valve opens again, the air in the accumulator forces the water under pressure through the membrane lumens, causing a pressure pulse and flow perturbations that lift, shift and break up the fouling layer. During 3 such "lift-and-sweep" events, the cake is lifted and the debris is swept out of the lumen. Experimental results for uninterrupted dead-end filtration at a UF pilot plant using RIP only on a severely fouled membrane, indicated that the RIP increased the flux by 18.4 % and decreased the dP by 8.2 % over a 7.2 h period. The method is effective in removing the cake layer intermittently and no long-term flux decline occurred for a period of 555 h since the previous chemical cleaning.
AFRIKAANSE OPSOMMING: Die doel van die tesis was om die gebruik van vloei-destabiliserings metodes, alleen of gekombineer met permeaat-terugwas, op vloed-herwinning en instandhouding in kapillêre UF membraan-stelsels tydens kruisvloei en doodloop bedryf, te ondersoek. Verskeie meganiese en hidrouliese metodes word gebruik in membraan stelsels om die koeklaag op die membraan se oppervlak te verwyder en die gestadigde-toestand vloed te verbeter. Vanhierdie metodes word permeaat-terugwas die meeste gebruik, maar het sy nadele insluitend verlies van produk en produksietyd. In 'n loodsstudie vir die ultrafiltrasie van oppervlakwaters wat hoë beladings NOM, turbiditeit en katione bevat, is die waarneming gemaak dat kruisvloei terugwas met vloeidestabilisering (voerrigting-verandering) die genormaliseerde vloed met 10.7 ± 3.4 % kon verbeter, vergeleke met 'n 3.2 ± l.6 % verbetering sonder voerrigting-verandering. Vir 'n tweede terugwas was die verbetering 7.0 ± 2.0 % vergeleke met 4.3 ± 2.5 % sonder voerrigtingverandering. Die hipotese was voorgestel dat die vloei-destabilisering die geoiënteerde koeklaag van die oppervlak gelig het, en die kruisvloei terugwas die geligde koeklaag uit die lumen kon vee. Indien hierdie vloei-destabilisering bewerk kan word deur 'n eenvoudige maar effektiewe manier, en indien dit gekombineer kan word met terugvloei van produk vir kort tydperke, sal hierdie "lig-en-vee" benadering die ideale metode wees om die membrane se vloed te verbeter en leeftyd te verleng. So 'n vloei-destabiliseringsmetode, nou genoem "terugdruk-pulsering", is ontwikkel. Die metode behels die sirkuiering van voer-water vir 2 s in 'n hersirkulasielus om momentum op te bou, gevolg deur die toemaak van 'n snel-aksie klep stroom-op van die modules. Die water in die konsentraat-lus se momentum dra dit vorentoe tot in In lug-gevulde voer-akkumulator, terwyl konsentraat en terug-vloei permeaat (wat ook tot 'n mate die koeklaag lig) ook na die atmosfeer gewend word vir 15 s deur die hersirkulasiepomp. As die klep weer oopgaan, ontspan die lug in die akkumulator, en forseer die water daarin onder druk deur die membraan-lumens. Die druk-puls en vloei-perturbasies lig, skuif en breek die koeklaag op. Tydens 3 agtereenvolgende "lig-en-vee" aksies word die koeklaag effektief opgebreek en uit die lumen gevee. Eksperimentele uitslae vir ononderbroke doodloop bedryf op uitermate aangevuilde membrane van 'n ultrafiltrasie loodsaanleg toegerus met terugdruk-pulsering, het getoon dat die vloed met 18.4 % verbeter kon word en die dP met 8.2 % verminder kon word in slegs 7.2 h. Die metode breek die koeklaag effektief op, en geen langtermyn vloed-afname is waargeneem vir meer as 555 h sedert die vorige chemiese was-prosedure nie.
Al-Atta, Ammar Jaber. "Supercritical water oxidation of hazardous waste : process enhancement and reactor design." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/53356/.
Full textWaletzko, Ryan Scott. "Determining soft segment structure-property effects in the enhancement of segmented polyurethane performance." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/46671.
Full textIncludes bibliographical references.
Liquid Crystalline Elastomer (LCE)-inspired segmented polyurethane elastomers possessing widely different extents of ordering were created to mimic the hierarchical structure of the continuous matrix and superior mechanical performance of spider silk fibers. The silk's remarkable toughness originates from a fiber morphology that possesses [beta]-pleated crystalline sheets within an amorphous matrix. In the polyurethane materials, various extents of poly(ethylene oxide) (PEO) soft segment ordering were implemented within continuous soft domains that were connected by hexamethylene diisocyanate-butanediol (HDI-BDO) hard segments. Soft segment crystallinity studies revealed the need to optimize the extent of continuous soft domain ordering. Highly crystalline PEO soft segments, while they display good microphase segregation properties, sacrifice extensibility due to their high melting transition temperature. Moderately crystalline PEO soft segments, meanwhile, possess less defined phase segregation but enhanced mechanical properties from their reversible dispersed crystalline soft segment domains. Non-crystalline Pluronic copolymer systems had good mechanical properties that resulted from both a strong hard segment incompatibility and a highly mobile soft segment matrix. Hydrogen-bonded hard domain shearing during in-situ tensile deformation yields oriented hard blocks that align at a preferred tilt angle of ±60° from the strain direction. Extensive alignment and orientation of the moderately-ordered PEO soft segments occurred during deformation, which was consistent with its observed mechanical behavior. Pluronic-containing segmented polyurethanes formed an ordered mesophase in the continuous soft matrix during deformation. A series of cyclic, aliphatic polyurethanes with dicyclohexyl methane diisocyanate (HMDI) hard segments and poly(tetramethylene oxide) (PTMO) soft segments was synthesized to study compositional effects on the extent of soft segment mixing, and how these effects translated to both mechanical and barrier performance. Shorter soft segment chain systems displayed a greater hard segment compatibility, which resulted in materials that were both more rigid mechanically and provided better barrier characteristics.
(cont.) Longer soft segments in the continuous polymer matrix displayed a more phase segregated structure, which enhanced their mechanical properties but sacrificed barrier effectiveness. Incorporation of dimethyl propane diol (DMPD), a branched chain extender, created a completely amorphous polyurethane matrix. Polyurethane/Laponite nanocomposites were also created using particles that were capable of preferentially associating with hard or soft segments. HMDI-BDO-PTMO polyurethane/Laponite nanocomposites demonstrated drastically reduced mechanical performance (~13-fold decrease in toughness and ~10-fold decrease in extensibility). The deteriorated mechanical performance was attributed to the formation of an interconnected hard segment continuous morphology that significantly reduced matrix extensibility. HMDI-DMPDPTMO polyurethane/Laponite composites, on the other hand, only experienced modest reductions in extensibility (-70% of total initial extensibility) while maintaining toughess and increasing initial modulus 10-fold. Mechanical behavior resulted from well-dispersed Laponite clay platelets that reinforced the amorphous polymer matrix while imposing modest chain segmental mobility restrictions.
by Ryan Scott Waletzko.
Ph.D.
Valentine, Mark Edward. "Fundamental flux enhancement modelling of membrane microfiltration." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:f1b0388e-25b9-4038-be04-360b1414d172.
Full textPeng, Xiaodong. "Liquid air energy storage : process optimization and performance enhancement." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8615/.
Full textIbrahim, Sarah A. "A Structure-Enhancement Relationship and Mechanistic Study of Chemical Enhancers on Human Epidermal Membrane based on Maximum Enhancement Effect (Emax)." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1266598335.
Full textMaxson, Andrew. "Heat Transfer Enhancement in Turbulent Drag Reducing Surfactant Solutions." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500419520976994.
Full textHassan, Faiza. "Heterogeneous catalysis in supercritical fluids : the enhancement of catalytic stability to coking." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/3166/.
Full textZak, Andrew Joseph. "Determining the Transport Enhancement of Sodium Fluorescein in Mechanically-Loaded Canine Tibia." Cleveland State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=csu1449314893.
Full textAlsoqyani, Faihan Saleh. "Supercritical water oxidation of nitrogen-containing organic compounds : process enhancement using isopropyl alcohol." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7296/.
Full textShi, Haifeng. "Surfactant Drag Reduction and Heat Transfer Enhancement." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343664380.
Full textMuniz, Maisonet Maritza. "Topographical Enhancement of Cell Adhesion on Poorly Adhesive Materials." Scholar Commons, 2015. https://scholarcommons.usf.edu/etd/5748.
Full textSumair, Faisal Ahmed. "Preparation and characterisation of eutectic nanofluids for heat transfer enhancement in flat plate solar collectors." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/48390/.
Full textLatorre, Federico [Verfasser], Leticia Gutachter] Gonzales, and Volker [Gutachter] [Deckert. "Quantum chemical investigation towards Raman enhancement effects / Federico Latorre ; Gutachter: Leticia Gonzales, Volker Deckert." Jena : Friedrich-Schiller-Universität Jena, 2017. http://d-nb.info/1177599740/34.
Full textMatthews, Ben J. H. "The rate of air-sea COâ‚‚ exchange : chemical enhancement and catalysis by marine microalgae." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323350.
Full textMarr, Kevin M. "Transport Enhancement of Rate-Limited Chemical Reactions via Pt-Decorated, Carbon Nanotube Microarray Membranes." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5537.
Full textNaseer, Zarga. "Chemical and physical changes associated with maturity of different plants and enhancement of nutritional value by chemical treatment of crop residues." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07122007-103928/.
Full textBryden, Michelle D. (Michelle Denise). "Transport in Lagrangian-unsteady flows : dipersion in diverging or converging ducts, and transport rate enhancement accompanying laminar chaos." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/46053.
Full textHozhabr, Sassan. "Enhancement of interfacial adhesion in polymer blends of polypropylene and poly (ethylene vinyl alcohol copolymer)." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60598.
Full textThe results in the batch mixer demonstrated that blends containing high levels of MAH have well bonded morphology and impact strengths comparable to pure materials. Statistical analysis of the results showed that at processing temperature of 200$ sp circ$C and mixing time of 13 minutes, the highest impact strength and largest elongation at break were obtained.
In the extruder the morphological studies revealed the presence of a layered structure in the core region of the samples when a slit die was employed. The oxygen permeability of extruded samples with EVOH content higher than 20vol% resembled multi-layer systems.
Impact strength of extruded ribbons drastically improved by increasing the maleation level to 0.2wt% and precompounding the virgin resins in a twin screw extruder. Morphological observations however, revealed some disruption in the layered structure and consequently decline of oxygen barrier properties.
Dadafarin, Hesam. "Electrochemically-assisted functionalization of a 316L stainless steel surface with fibronectin: towards the enhancement of biocompatibility of coronary stents." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114476.
Full textLes maladies cardiovasculaires (MCV) sont la primaire cause de décès dans les pays développés. Parmi les différents types de maladies cardiovasculaires, l'athérosclérose est une maladie fréquente et répandue. Il est caractérisé principalement par la formation d'une plaque, ce qui entraîne un rétrécissement considérable (sténose) et le durcissement des artères. Cependant, toutes les endoprothèses vasculaires actuelles offrent une biocompatibilité faible ce qui résulte en la présence d'intra- endoprothèse vasculaire thrombose et une resténose chez environ 30 % des patients et la nécessité de traitement médical supplémentaire. Des approches diverses qui consistenten la modification de la surface des endoprothèses vasculaires ont été utilisées afin de minimiser la resténose intra-endoprothèse vasculaire, mais aucune d'entre elles n'a prouvé être satisfaisante à long terme. Le but de ce travail a été de développer une nouvelle méthode pour la modification de la surface de l'endoprothèse vasculaire, dans le but de réduire le taux de resténose intra-endoprothèse vasculaire. Le but ultime du projet était de rendre fonctionnant làcier inoxydable 316L, CoCr et les surfaces NiTi avec une matrice chimiquement liée et extracellulaire de la protéine fibronectine (Fn) avec le but de contrôler et de se faire le médiateur de l`interaction entre les cellules endothéliales (CE) et des cellules musculaires (CML). Dans ce projet, une nouvelle méthode basée sur l'électrochimie pour immobiliser le Fn sur l'acier inoxydable 316L, CoCr et les surfaces NiTi a été développé. La méthode est basé sur la formation d'une monocouche stable d'alcanethiol sur la surface de l'alliage, qui a été plus modifiée chimiquement pour permettre la fixation covalente de Fn. La Spectroscopie InfraRouge de Réflexion Absorption Modulation Polarisation (PM-IRRAS) a révélé que la monocouche d'alcanethiol formée est relativement ordonnée. La spectroscopie des photélectrons X-ray (XPS) a démontré que la monocouche est fixée sur la surface ende làcier inoxydable par l'atome de soufre. À long terme, des expériences de spectroscopie d'impédance électrochimique ont démontré que la monocouche formée a également fourni une barrière de diffusion pour les ions agressifs/corrosifs, ce qui donne un taux élevé (env. 94 %) d'efficacité en ce qui concerne la protection contre la corrosion de l'acier inoxydable 316L.Il a été déterminé que la liaison covalente entre Fn et la monocouche d'alcanethiol préformée sur l'acier inoxydable 316L, CoCr et les surfaces en NiTi, a résulté à la formation d'une couche de protéine très stable. PM-IRRAS indique que la fixation covalente du Fn a entraîné un changement dans la structure secondaire de la protéine. Microscopie électronique à balayage (MEB) et de dispersion d'énergie X-Ray (EDX) des molécules Fn immobilisées sur une stent commerciale en acier inoxydable 316L cardiovasculaire a révélé une distribution spatiale homogène de Fn et l'espacement moléculaire était approprié pour l'adhérence des cellules. L'effet de l'immobilisation de Fn sur une surface dàcier inoxydable 316L, sur le comportement entre la surface et la cellule a été plus abondamment étudié en examinant l'interaction entre les plaquettes, les CPP et les CML. Un taux inférieur d'adhérence et d'agrégation plaquettaire a été observé sur les surfaces modifiées avec Fn, ce qu'implique une thrombogénicité de la surface. Il a été démontré que la présence de Fn sur la surface a amélioré considérablement la fixation CE et aucune amélioration dans l'adhérence SMC n'a été observée. Une augmentation des taux de prolifération des ECs et SMCs a été réalisé sur les surfaces modifiées avec Fn. L'étude comparative de l'attachement EC et SMC a révélé que les surfaces Fn modifiées attirent sélectivement plus les ECs que les SMCs. Ca indique une meilleure biocompatibilité des surfaces modifiées avec Fn pour des applications coronaires endoprothèse vasculaire.
Rodriguez-Chiang, Lourdes. "Enhancement of methane production from the anaerobic digestion of chemical pulp and paper mill effluents." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/669251.
Full textLa sostenibilidad en la gestión de recursos como la energía, el agua y los residuos se ha convertido en un aspecto clave en nuestra economía actual. Para grandes industrias que consumen mucha agua y energía, como la industria de pulpa y papel (P&P) este es un tema especialmente relevante. Los grandes y heterogéneos volúmenes de efluentes que producen las fábricas de P&P hacen que su adecuado tratamiento sea una tarea difícil. La digestión anaerobia es una tecnología eficiente para el tratamiento de aguas residuales; que limpia el efluente, reduce el lodo producido y simultáneamente produce metano que puede usarse como fuente de energía. El objetivo del trabajo de investigación descrito en esta tesis es aumentar la producción de metano a partir de la digestión anaerobia de diferentes efluentes producidos en fábricas de pulpa. A través de la caracterización del efluente, determinación de parámetros del proceso, agentes promotores y la evaluación de pruebas de producción de metano bioquímico se evaluaron los beneficios de tres métodos potenciales para mejorar los rendimientos de metano de los efluentes. Asimismo, se exploró la conversión directa de fibras de pulpa química a metano. Los efluentes fácilmente degradables, como los filtrados hidrolizados y los condensados del evaporador, contienen altas concentraciones de azúcares y ácido acético, respectivamente, lo que podría provocar una sobresaturación de ácidos durante la acidogénesis. Se ha demostrado que una relación de inóculo a sustrato de 2 resulta óptima para aumentar la capacidad tampón del sistema y neutralizar el pH y producir rendimientos de metano significativamente altos, de hasta 333 mLCH4/gVS. La alta productividad de estos efluentes hace que se puedan considerar para la co-digestión con efluentes más difíciles de tratar, como las aguas ricas en lignina. Claramente la lignina obstaculiza la producción de metano, tal y como indica la correlación lineal negativa encontrada entre el contenido de lignina y el rendimiento de metano. La co-digestión del efluente rico en lignina con el condensado de evaporadores de pulpa semi-química de sulfito ha demostrado mejorar la productividad de metano en el tratamiento de aguas residuales de la planta. Además, la adición de hidrotalcitas (HT) como catatlizadores contribuye hacia un aumento en la producción de metano, tasas de producción más rápidas y una mayor eliminación de lignina. Con HT calcinadas se han obtenido rendimientos bajos, lo que sugiere que las ventajas de la adición de HT provienen de su estructura laminar. Finalmente, además de establecer el potencial de metano que existen en los efluentes de P&P, la evaluación de la productividad de metano de diferentes fibras de pulpa y sus productos ha demostrado ser una nueva alternativa energética para explorar. El uso de pulpa blanqueada, sin blanquear y deslignificada con oxígeno muestran biodegradabilidades de hasta 90% y rendimientos de metano de hasta 380 mLCH4/gVS. Con la cambiante bioeconomía actual, este último enfoque estimula la exploración de usos alternativos y novedosos para productos de plantas de pulpa química.
Chui, Yiu Loon. "Mechanisms of long term rat kidney allograft survival induced by chemical immunosuppression or immunological enhancement." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/37975.
Full textPap, Ilona. "Productivity enhancement in optical semiconductor manufacturing: Early warning of failures in BHet laser fabrication." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26736.
Full textHagelin, Johnny. "Enhancement of hydrolysis from co-fermentation of food waste and primary sludge." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299643.
Full textMer uppmärksamhet riktas till forskning kring resursåtervinning från komplexa avfallsströmmar eftersom värdefulla resurser kan produceras genom mer hållbara biologiska tillvägagångssätt. I anaeroba nedbrytningsprocesser är produkter såsom flyktiga fettsyror (VFAs) och biogas mycket eftertraktade. En av huvudparametrarna som påverkar utbytet av återvunna resurser är den hydrolytiska effektiviteten i avfallsströmmen av hydrolytiska bakterier. Syftet med studien var att undersöka hur bioaugmentering kan implementeras som strategi för att förstärka hydrolys i komplexa avfallsströmmar. Därav utfördes fermentering med tre valda hydrolytiska bakterier, Bacteroides thetaiotaomicron, Bacteroides amylophilus och Bacteroides ruminicola både i renkultur och bioaugmenterat med granulärt slam som mixad kultur i reaktorer. Avfallsströmmen som studerades var matavfall mixat med primärt slam hämtat från Henriksdals vattenreningsverk i Stockholm, Sverige. Högsta hydrolytiska effektivitet (90%) uppnåddes för reaktorn inokulerat med Bacteroides thetaiotaomicron och Bacteroides ruminicola i renkultur. Denna effektivitet uppmättes dag 10 efter reaktorerna sattes upp. För de bioaugmenterade reaktorerna så uppnåddes högsta hydrolytiska effektivitet (66%) dag 10 av reaktorn inokulerat med Bacteroides thetaiotaomicron. Ökningen i hydrolytisk effektivitet var långsammare för de bioaugmenterade reaktorerna jämfört med reaktorerna med renkultur. Den mest sannolika förklaringen till det är tävling om näringsämnen och vitaminer mellan introducerade bakterier och de bakterier som redan existerar i det granulära slammet.
Kashfipour, Marjan Alsadat. "Thermal Conductivity Enhancement Of Polymer Based Materials." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron156415885613422.
Full textBoss, Michael. "The Role of Diffusion in NMR Proton Relaxation Enhancement by Ferritin." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1275484465.
Full textHabibzadeh, Sajjad. "Employment of Ir/Ti-oxide coatings and electrochemical polishing of a 316L stainless steel surface for the enhancement of biocompatibility of coronary stents." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121444.
Full textEndoprothèses vasculaires métalliques sont des dispositifs médicaux (implantes) qui peuvent fournir des échafaudages endovasculaire afin de soulager une obstruction vasculaire et minimiser le risque d'infarctus du myocarde (crise cardiaque). Cependant, les prothèses actuels sont considérés d'offrir mauvais bio/hémocompatibilité, car leur surface provoque une réaction tissulaire indésirable lors de l'implantation.Dans la plupart des cas, cela se traduit par une resténose intra-prothèses (re-blocage des vaisseaux sanguins au niveau du site d'implantation). Alors, diverses caractéristiques de surface des prothèses jouent un rôle déterminant dans leur biocompatibilité et subséquemment leur fonctionnalité et sécurité. Par conséquent, afin d'augmenter la bio/hémocompatibilité de prothèses s, une méthode de modification de surface appropriée peut être utilisée pour ajuster la texture de la surface du stprothèses et les propriétés physico-chimiques de manière à favoriser les interactions cellulaires/surface souhaitables et rendre la surface des prothèses plus électrochimique stable (résistant à la corrosion).Le but de ce travail était d'étudier la possibilité d'augmenter un bio/hémocompatibilité d'une surface métallique en utilisant deux approches de modification de surface: (i) la formation de revêtements IrxTi1-x-oxyde (x = 0, 0,2, 0,4, 0,6, 0.8 et 1) sur un substrat de Ti et sur une base commerciale acier inoxydable 316L (316L-SS) prothèses coronariens et (ii) le polissage électrochimique d'une surface 316L-SS. La première approche a également été utilisée dans le but d'augmenter la radio-opacité des prothèses (visibilité). Des techniques électrochimiques et surface-caractérisation ont été utilisées pour étudier la topographie/morphologie de la surface, la structure et la composition chimique des revêtements Ir/Ti-oxyde, ainsi que leurs propriétés électrochimiques et des radio-opacité. Ces propriétés ont été trouvés fortement dépendent de la composition de revêtement. Tous les revêtements ont été jugées électrochimiquement stables dans les conditions expérimentales utilisées dans la recherche. 316L-SS prothèses coronaires modifiés par des revêtements Ir/Ti-oxyde ont été trouvés à être plus radio-opaque que celui sans revêtements 316L-SS prothèses. Le revêtement Ir0.4Ti0.6-oxyde a été montré pour être le plus uniforme, résistant à la corrosion et radio-opaque. Spectrométrie photoélectron du rayon-X résultats de spectroscopie de photoélectrons ont révélé que les films d'oxyde du EP ont été caractérisées par une proportion beaucoup plus élevé atomique Cr/Fe et d'épaisseur de film, par rapport au film d'oxyde passif naturellement développée formée sur la surface non traitée 316L-SS. Un particulièrement enrichissement élevé avec des espèces Cr a été enregistré à la couche la plus externe des films d'oxyde EP. En raison de l'augmentation de l'épaisseur du film d'oxyde et enrichissement relatif Cr, les surfaces 316-SS EP-traités offert une amélioration notable de la résistance à la corrosion générale et piqûres. L'influence des méthodes de modification de surface utilisés sur la bio/hémocompatibilité a été étudiée. Ceci a été implémenté en examinant l'interaction des plaquettes, des cellules endothéliales (EC) et les cellules musculaires lisses (SMC) avec les surfaces modifiées. Les expériences sur l'interaction entre la cellule et la surface ont révélé un plus grand ratio de fixation EC/SMC pour Ir0.2Ti0.8-oxyde, Ir0.4Ti0.6-oxyde et les trois surfaces du EP, lorsque en comparant avec la contrôle 316L-SS. Ceci. Ainsi, les surfaces modifiées permettront une endothélialisation plus rapide, ce qui les rend potentiellement supérieure pour les applications de prothèses coronaire.
Van, den Berg Jacobus A. "The utilisation of the ash disposal system as a salt sink : enhancement and optimisation of chemical interactions." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16450.
Full textENGLISH ABSTRACT: The fine ash produced at the Sasol Secunda Petrochemical Plant is disposed of through a wet ash disposal system. Other process waste streams with high salt concentrations are co-disposed of in the Sasol Secunda ash disposal system. This has led to a steady rise in the salt concentrations of the recycled clear ash effluent (CAE) over the past 17 years. To combat this increase in salt concentrations, the capability of the Sasol Secunda ash disposal system to act as a salt sink, needs to be enhanced. This investigation focussed on ways to enhance the salt removal/retention capabilities of the Sasol Secunda ash disposal system and consisted of the following: • A literature survey of relevant information. • The mixing of different combinations of fine ash, brine and CAE. • Adding CO2 to the fine ash and CAE mixtures. • Investigation to enhance salt precipitation in the CAE and Evaporation dams. • Salt balances and a residence time calculation over the CAE and Evaporation dams. From these investigations it were concluded that the Sasol Secunda ash disposal system could be used as a salt sink for SO4 ions. Up to 43% of the SO4 is removed from the brines after the initial ash/water contact. It was also found that the tubular reverse osmosis (TRO) brine could be used as a carrier medium for the ash. The large amounts of Ca that is leached into the ash water during the mixing of the CAE and fine ash can be prevented by the addition of CO2 to the mixing point. There is usually an increase of 240% in the Ca concentration and this is reduced to only an 8% increase with the CO2 addition. The most feasible precipitation enhancement for the CAE and Evaporation dams is an increase in evaporation. This enhances CaCO3 precipitation, which is the main mechanism for salt removal in the CAE and Evaporation dams. Ca, Na and Cl are retained in the evaporation and CAE dams. SO4 is leached from solid phases in the dams. There is however an overall decrease in the total dissolved solids (TDS) of the ash water. The salt removal of the CAE and Evaporation dams is approximately 57 tons per day. The capability of the Sasol Secunda ash disposal system to act as a salt sink can be enhanced by the addition of CO2 at the mixing point and by increasing the evaporation rate in the CAE and Evaporation dams. Using the TRO brine as carrier medium may also increase the SO4 precipitation capabilities of the Sasol Secunda ash disposal system.
AFRIKAANSE OPSOMMING: Die fynas wat by die Sasol Secunda Petrochemiese Aanleg geproduseer word, word verwyder deur ‘n geslote nat asstelsel. Ander afvalstrome wat hoë konsentrasies soute bevat word ook in die Sasol Secunda asstelsel gestort. Dit het tot gevolg dat daar oor die afgelope 17 jaar ‘n volgehoue styging in die sout konsentrasies van die hergebruikte aswater (genoem CAE – “clear ash effluent”) was. ‘n Manier om hierdie styging in die sout konsentrasies teen te werk, is om die sout verwyderingsvermoë van die Sasol Secunda asstelsel te verbeter. Hierdie ondersoek het gefokus op maniere om die sout verwyderings- /terughoudingsvermoë van die Sasol Secunda asstelsel te verbeter en het die volgende ingesluit: • ‘n Literatuur oorsig van toepaslike inligting. • Die meng van verskillende kombinasies van fynas, soutstrome en CAE. • Toediening van CO2 by die fynas en CAE mengsels. • ‘n Ondersoek na metodes om die soutverwydering in die CAE en Verdampingsdamme te verbeter. • Soutbalanse en ‘n residensie tyd berekening vir die CAE en Verdampingsdamme. Na hierdie ondersoeke kon die gevolgtrekking gemaak word dat die Sasol Secunda asstelsel ‘n sout sink vir SO4 ione is. Tot 43% van die SO4 word verwyder na die aanvanklike as/water kontak. Daar is ook gevind dat die TRO (“tubular reverse osmosis”) soutstroom gebruik kan word as ‘n draer vir die fynas. Die groot hoeveelhede Ca wat in die aswater in loog, kan voorkom word deur die toediening van CO2 by die mengpunt van die fynas en aswater. Daar is normaalweg ‘n verhoging van 240% in die Ca konsentrasie van die aswater en dit word verminder na ‘n skrale 8% met die toediening van CO2. Die mees praktiese metode om die soutverwydering in die CAE en Verdampingsdamme te verbeter, is met die verhoging van die verdamping. Dit sal die neerslag van CaCO3, wat die meeste soutverwydering tot gevolg het, verhoog. Ca, Na en Cl word teruggehou in die Verdampings en CAE damme. SO4 loog uit soliede fases in die damme. Daar is wel ‘n afname in die algehele opgeloste spesies (“TDS”) van die aswater. Die soutverwydering van die Verdampings en CAE damme is ongeveer 57 ton per dag. Die vermoë van die Sasol Secunda asstelsel om as ‘n sout sink gebruik te word, kan verbeter word deur CO2 by die mengpunt by te voeg en die verdampingstempo in die Verdampings en CAE damme te verhoog. Die gebruik van die TRO pekelstroom as draer van die as kan die SO4 neerslag in die Sasol Secunda asstelsel ook verhoog.
Olsson, Kevin. "Optimization of gas flow uniformity in enhancement of Metal Organic Chemical Vapor Deposition growth for III-nitrides." Thesis, Linköpings universitet, Halvledarmaterial, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157378.
Full textDickerson, Matthew Thomas. "PROTEIN BASED BIOMIMETIC APPROACHS TO SURFACE HEMOCOMPATIBILITY AND BIOCOMPATIBILITY ENHANCEMENT." UKnowledge, 2012. http://uknowledge.uky.edu/cme_etds/6.
Full textUpamali, Karasinghe A. Nadeeka. "Carbazole-Based, Self-Assembled, Π-Conjugated Systems As Fluorescent Micro And Nanomaterials - Synthesis, Photophysical Properties, Emission Enhancement And Chemical Sensing." Bowling Green State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1323099511.
Full textMyers, Philip D. Jr. "Additives for Heat Transfer Enhancement in High Temperature Thermal Energy Storage Media: Selection and Characterization." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5749.
Full textShapero-Holder, Barbara C. "Contributory role status and the development and treatment of chemical dependence a contextual enhancement of current recovery models /." View full text, 2003.
Find full textKuhlman, Andrew. "An Ab-Initio Study on the Chemical Modification of Raman Spectra of Organic Adsorbates on Semiconductor Surfaces." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1402334244.
Full textOrgill, James J. "Enhancement of Mass Transfer and Electron Usage for Syngas Fermentation." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4029.
Full textGiberti, Sara. "Surface Area enhancement of biochar and forestry biomass through activation by means of chemical impregnation with ZnCl2 and H3PO4." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Find full textJohnsen, Kim. "Sorption-enhanced steam methane reforming in fluidized bed reactors." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-994.
Full textHydrogen is considered to be an important potential energy carrier; however, its advantages are unlikely to be realized unless efficient means can be found to produce it without generation of CO2. Sorption-enhanced steam methane reforming (SE-SMR) represent a novel, energy-efficient hydrogen production route with in situ CO2 capture, shifting the reforming and water gas shift reactions beyond their conventional thermodynamic limits.
The use of fluidized bed reactors for SE-SMR has been investigated. Arctic dolomite, a calcium-based natural sorbent, was chosen as the primary CO2-acceptor in this study due to high absorption capacity, relatively high reaction rate and low cost. An experimental investigation was conducted in a bubbling fluidized bed reactor of diameter 0.1 m, which was operated cyclically and batchwise, alternating between reforming/carbonation conditions and higher-temperature calcination conditions. Hydrogen concentrations of >98 mole% on a dry basis were reached at 600°C and 1 atm, for superficial gas velocities in the range of ~0.03-0.1 m/s. Multiple reforming-regeneration cycles showed that the hydrogen concentration remained at ~98 mole% after four cycles. The total production time was reduced with an increasing number of cycles due to loss of CO2 -uptake capacity of the dolomite, but the reaction rates of steam reforming and carbonation seemed to be unaffected for the conditions investigated.
A modified shrinking core model was applied for deriving carbonation kinetics of Arctic dolomite, using experimental data from a novel thermo gravimetric reactor. An apparent activation energy of 32.6 kJ/mole was found from parameter fitting, which is in good agreement with previous reported results. The derived rate expression was able to predict experimental conversion up to ~30% very well, whereas the prediction of higher conversion levels was poorer. However, the residence time of sorbent in a continuous reformer-calciner system is likely to be rather low, so that only a fraction of the sorbent is utilized, highlighting the importance of the carbonation model at lower conversions.
A dual fluidized bed reactor for the SE-SMR system was modeled by using a simple two-phase hydrodynamic model, the experimentally derived carbonation kinetics and literature values for the kinetics of steam reforming and water gas shift reactions. The model delineates important features of the process. Hydrogen concentrations of >98 mole% were predicted for temperatures ~600°C and a superficial gas velocity of 0.1 m/s. The reformer temperature should not be lower than 540°C or greater than 630°C for carbon capture efficiencies to exceed 90%. Operating at relatively high solid circulation rates to reduce the need for fresh sorbent, is predicted to give higher system efficiencies than for the case where fresh solid is added. This finding is attributed to the additional energy required to decompose both CaCO3 and MgCO3 in fresh dolomite. Moreover, adding fresh sorbent is likely to result in catalyst loss in the purge stream, requiring sorbents with lifetimes comparable to those of the catalyst.
Thermo gravimetric analysis (TGA) was used to study the reversible CO2-uptake of sorbents. In general, the multi-cycle capacity of the dolomite was found rather poor. Therefore, synthetic sorbents that maintain their capacities upon multiple reforming-calcination cycles were investigated. A low-temperature liquid phase co-precipitation method was used for synthesis of Li2ZrO3 and Na2ZrO3. Li2ZrO3 showed a superior multi-cycle capacity compared to Arctic dolomite in TGA, but the rate of reaction in diluted CO2 atmospheres was very slow. The synthesized Na2ZrO3 proved to have both fast carbonation kinetics and stable multi-cycle performance. However, regeneration in the presence of carbon dioxide was not easily accomplished.
The findings of this thesis suggest that the bubbling fluidized bed reactor is an attractive reactor configuration for SE-SMR. Low gas throughput is the major disadvantage for this configuration, and operation in the fast fluidization regime is most likely to be preferred on an industrial scale of the process. Future work should focus on developing sorbents and catalysts that are suited for high velocity operation, with respect to reactivity and mechanical strength.