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1
Pandey, Sujata. "Design, Optimization and Characterization of Ibuprofen Microemulsions and Microemulsion-Based Gels." University of Toledo Health Science Campus / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=mco158894431613094.
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2
Bellich, Barbara. "Preparazione e caratterizzazione di forme farmaceutiche solide orali a partire da materiale composito." Doctoral thesis, Università degli studi di Trieste, 2008. http://hdl.handle.net/10077/2568.
Повний текст джерелаАнотація:
2006/2007La somministrazione per via orale è la preferita per il trattamento farmacologico cronico. Circa il 40% dei nuovi principi attivi, tra i quali numerosi potenti farmaci lipofilici, è caratterizzato da bassa solubilità in acqua e la somministrazione per via orale di tali farmaci è frequentemente associata a bassa biodisponibilità. Infatti l’assorbimento di un principio attivo rilasciato da una forma farmaceutica orale dipende essenzialmente da due fattori: la dissoluzione del p.a. nel tratto gastrointestinale e la sua permeabilità attraverso la mucosa. Sulla base di questi due parametri i principi attivi sono stati distinti in quattro classi (Biopharmaceutical Classification System). In particolare per la seconda classe di composti, la dissoluzione nel lume gastro-intestinale è lo step limitante il processo di assorbimento. Per questa classe, numerosi approcci tecnologici sono riportati in letteratura allo scopo di aumentare la biodisponibilità orale di farmaci lipofilici come per esempio l’incorporazione in veicoli lipidici inerti come olii, la formulazione di sistemi auto-emulsificanti, di emulsioni e microemulsioni, liposomi, complessi di inclusione e sistemi dispersi farmaco-carrier. Rispetto a tali metodi convenzionali, il lavoro svolto ha riguardato la preparazione di sistemi attivati a base di ubidecarenone e ciclosporina ricorrendo alla tecnologia NEC (Nanoemulsified Composites) in collaborazione con la ditta Remedia s.r.l. titolare della tecnologia brevettata. La tecnologia NEC si basa sull’incorporazione di una doppia microemulsione (o/a/o) in un carrier microporoso. Successivamente l’attenzione è stata focalizzata sull’innovativa applicabilità delle microonde alla preparazione di sistemi binari farmaco:carrier. Il riscaldamento per mezzo delle microonde sfrutta le proprietà che le sostanze chimiche hanno di assorbire l’energia direttamente dalle onde elettromagnetiche le quali sono in grado di aumentare l’agitazione termica, e quindi la temperatura. L’energia fornita dalle radiazioni viene ceduta direttamente alla sostanza ed in tempi molto brevi. Tutte le sostanze caratterizzate da un dipolo, anche minimo, possono assorbire microonde. In tale contesto, oggetto della ricerca è stata l’attivazione dell’ibuprofene e piroxicam. Per tutti i farmaci considerati è stato inizialmente effettuato uno studio di messa a punto delle sostanze e delle condizioni operative ottimali, atte a fornire un prodotto finale lavorabile (prodotto composito). Alla preparazione dei sistemi ha fatto seguito la caratterizzazione chimico-fisica, necessaria per appurare lo stato solido del principio attivo. In particolare le tecniche adottate sono state: calorimetria a scansione differenziale (DSC), raggi X su polvere (PXRD), microscopia elettronica (SEM), hotstage microscopi (HSM), laser-light scattering. Successivamente le formulazioni approntate sono state caratterizzate anche dal punto di vista tecnologico e dissolutivo in termini di studi di cinetica di solubilizzazione e di rilascio. Inoltre in alcuni casi il prodotto è stato testato in vivo su ratti. Ed è stata anche valutata, in alcuni casi, la possibilità di realizzare forme farmaceutiche solide ad uso orale quali capsule e compresse. I risultati ottenuti sono qui di seguito riassunti. UBIDECARENONE La tecnologia preparativa adottata unitamente alla selezione dei componenti, hanno dimostrato il raggiungimento dell’obiettivo del presente lavoro e cioè l’aumento della biodisponibilità in vivo dell’Ubidecarenone. Le caratteristiche tecnologiche del materiale composito hanno permesso un’agevole realizzazione di capsule rigide ma, con un’ulteriore selezione di eccipienti per compressione diretta, si potrà realizzare anche la forma di dosaggio in compresse. CICLOSPORINA Il prodotto composito preparato è dunque risultato essere in grado di aumentare la biodisponibilità in vivo della ciclosporina rispetto alla materia prima commerciale. IBUPROFENE Dai risultati ottenuti si può concludere che la tecnica utilizzata e i polimeri scelti hanno portato ad un grado di amorfizzazione del farmaco tale da essere responsabile dell’incremento del profilo di dissoluzione in vitro delle dispersioni solide (IBU:PVP/VA e IBU: HP-β-CD) rispetto ai campioni di confronto. PIROXICAM Anche in questo studio è stato possibile verificare l’applicabilità delle MW alla creazione di sistemi dispersi solvent-free. Gli indiscussi vantaggi al ricorso ad un reattore a MW focalizzate (CEM) in termini di tempi e potenze applicate sono stati verificati. Il raggiungimento dell’obiettivo del lavoro e cioè l’aumento della biodisponibilità in vitro del piroxicam è stato ottenuto associando alla tecnologia adottata il polimero PVP/VA 64.
XX Ciclo
1974
3
Taylor, Diana Jacqueline Falcon. "Temperature insensitive microemulsions." Thesis, University of Hull, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310404.
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4
Mertzman, Melissa Danielle Foley Joe Preston. "Chiral microemulsion electrokinetic chromatography /." Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/340.
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5
Kahle, Kimberly Ann Foley Joe Preston. "Effect of identity and number of chiral microemulsion components in chiral microemulsion electrokinetic chromatography /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/1293.
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6
Memon, Muhammad Hanif. "Microemulsions as analytical reaction media." Thesis, University of Hull, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235839.
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7
Mead, J. "Structure and reactivity in microemulsions." Thesis, University of Kent, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355149.
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8
Steudle, Anne Katharina. "Enzyme activity in bicontinuous microemulsions." Thesis, Durham University, 2015. http://etheses.dur.ac.uk/11178/.
Повний текст джерелаАнотація:
The thesis deals with enzymatic catalysis in bicontinuous microemulsions, which consist of a dynamic network of oil and water domains separated by a monolayer of surfactant molecules, i.e. the interfacial layer. Hence, a microemulsion with the composition buffer – n-octane – nonionic surfactant was tested as a reaction medium for enzyme-catalysed reactions with the emphasis on the conversion of hydrophobic substrates, which are difficult to convert in aqueous buffer solutions. The first part of the thesis focuses on the activity of the lipase B from Candida antarctica (CalB) in bicontinuous microemulsions. First, the optimum reaction conditions determined by temperature, pH and ionic strength were evaluated. Second, it was found that CalB concentrations which showed fast adsorption at an oil-water interface also displayed fast reaction rates. Additionally, no saturation was found for substrate concentrations up to 40 mM of p-nitrophenyl laurate, which according to Michaelis-Menten suggests a Km >> 40 mM. Third, the composition of the interfacial layer had a distinct influence on CalB activity, e.g. the presence of sugar surfactants (b-C10G1) or phospholipids (DOPC) enhanced or decreased CalB activity, respectively. The second part of the thesis describes the activity of the squalene-hopene cyclase from Alicyclobacillus acidocaldarius (Aac SHC) converting its natural substrate squalene in bicontinuous microemulsions. The Aac SHC activity studies revealed a linear dependence on enzyme concentration and a hyperbolic curve for the substrate concentration, with a saturation of Aac SHC at substrate concentrations above 20 mM. The composition of the interfacial layer was found to have neither a significant influence on the activity nor on the conformation of Aac SHC. In summary, good turnover rates were achieved for interfacially-active enzymes (CalB) due to enhanced enzyme-substrate contact at the interfacial layer. For water-soluble enzymes (Aac SHC), a distinctly enhanced selectivity was discovered, although no faster reaction rate was found. The main difference in the catalytic turnover was explained by the adsorption of CalB at the interfacial layer, whereas Aac SHC stays in the aqueous phase of the microemulsion. To conclude, bicontinuous microemulsions were suitable for enzymatic catalysis and are thus interesting in terms of reaction medium engineering to optimise biocatalytic processes.
9
Biggs, Simon Richard. "Block copolymers in microemulsion systems." Thesis, University of Bristol, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303769.
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10
Radiman, Shahidan. "Structural characterisation of microemulsion systems." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333282.
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11
Marcus, Julien [Verfasser], and Werner [Akademischer Betreuer] Kunz. "Study of surfactant-free microemulsions and microemulsions with fatty acid salts / Julien Marcus. Betreuer: Werner Kunz." Regensburg : Universitätsbibliothek Regensburg, 2016. http://d-nb.info/1081543353/34.
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12
Akhtar, Mahmood. "Microemulsions formation, stability and their characterisations." Thesis, Brunel University, 1996. http://bura.brunel.ac.uk/handle/2438/5004.
Повний текст джерелаАнотація:
This thesis is concerned with aspects of the surface and colloid chemistry of various microemulsion systems stabilised by pure nonionic surfactants and alcohol as well as mixtures of nonionic and anionic surfactants. Phase equilibria and interfacial characteristics of the systems are studied with a view to their potential usefulness for enhanced oil recovery, in which salinity and temperature are important parameters. The equilibrium microemulsion phases are scanned at different temperatures and salinities and thus interfacial boundaries can be determined and optimum salinity scans can be performed accurately using a modified spectrophotometer. Several analytical techniques (e.g., high performance liquid chromatography, gas chromatography, ion-exchange chromatography, mass spectrometry, viscometry, electrical conductivity, photon correlation spectroscopy, UV-spectrophotometry, thermogravimetric analysis, transmission electron microscopy, surface and interfacial tension techniques) have been used to characterise and understand the microchemistry of the microemulsion systems. Ultra-low interfacial tensions (>0.1 µN/m) can be achieved in the microemulsion systems. Surfactant transfer between phases, and phase inversion of micro emulsions are shown to occur around the condition which produces minimum interfacial tension. Adsorption of the surfactants from aqueous and nonaqueous solutions has been investigated and the results show that the extent of adsorption can be reduced significantly in the presence of alcohols (co-solvent). The extent of adsorption increases with increasing temperature and salinity; however, it decreases with an increase in the hydrophilic head group of the surfactant. Adsorption of nonionic surfactants on quartz from the nonaqueous solution (decane) is much greater than from aqueous solution. In microemulsion applications, droplet combustion of w/o microemulsions is also studied for different surfaces (i.e. silica, oxidised Fecralloy and catalyst coated Fecralloy) in the temperature range of 313-573K. Formaldehyde and acetaldehyde are formed as intermediate combustion products. Thus the microemulsion combustion can lead to new oxygenate products. The w/o microemulsion route is used to synthesize colloidal silica of controlled particle size and morphology. The particle size can be varied by changing the molar ratio of water to TEOS using a water pH of 10.5.
13
Billman, John Frederick. "Structure and phase behavior in microemulsions /." Thesis, Connect to this title online; UW restricted, 1990. http://hdl.handle.net/1773/9825.
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14
Husein, Maen. "Nucleophilic sulfonation in microemulsions and emulsions." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36814.
Повний текст джерелаАнотація:
The nucleophilic sulfonation of decyl halides and benzyl halides was carried out at 298.2 K in batches in o/w microemulsions and emulsions formed with the two-tailed cationic surfactants dioctyldimethylammomum chloride, R2(Me)2N +Cl-, or bromide, R2(Me) 2N+Br-. The effects of mixing, surfactant concentration and counterion, and reactant concentrations on the conversion of the halide were investigated. At the concentrations employed, phase separation occurred in most of the samples. Mixing did not affect the sulfonation of decyl halides, while it governed the sulfonation rate of benzyl halides. Chloride as the surfactant counterion reacted with the bromide and iodide halides to form an intermediate, decyl chloride, and a side product, benzyl chloride. At a fixed time, the conversion to the final product versus surfactant concentration displayed a broad maximum. The tendency of sodium decyl sulfonate to remain at the interface resulted in lower conversion with increasing decyl halide concentration, while the formation of a separate benzyl halide phase produced the same effect. Increasing the mole ratio sodium sulfite/halide reactant increased the conversion to the final product in a manner that supports the mechanisms of ion exchange with the surfactant counterions and a second order nucleophilic substitution.A single-pseudophase and a three-pseudophase model described the sulfonation of decyl halides and benzyl halides, respectively. The three new assumptions employed in the model are: (1) the volume of the interfacial region varies only with the amount of surfactant added, (2) the oil-soluble reactant may be unavailable for reaction if there is insufficient surfactant to bind all of the decyl halide to the interface, or insufficient mixing to eliminate the benzyl halide phase, and (3) a single ion exchange constant accounts for the exchange of three different anions at the interface.
15
Dowding, Peter John. "Characterisation of microemulsions containing silicone oils." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309956.
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16
Svensson, B. Martin. "Lipase catalysis in lecithin-stabilised microemulsions." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406836.
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17
Warisnoicharoen, Warangkana. "Pharmaceutical nonionic oil-in-water microemulsions." Thesis, King's College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286790.
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18
Peter, Ulrike. "Extremely diluted microemulsions : structure and dynamics." Bordeaux 1, 2000. http://www.theses.fr/2000BOR1A001.
Повний текст джерелаАнотація:
@Les microémulsions sont des phases de films flexibles de tensioactifs à l'interface entre l'eau et l'huile. Leur stabilité est déterminée par une compétition entre l'entropie du système et l'énergie élastique du film interfacial. Dans les systèmes de microémulsions classiquement étudiés, la constante élastique K de courbure du film est de l'ordre de kBT. Nous nous intéressons à un système contenant des interfaces plus rigides. Toutefois, l'interface est choisie telle que K reste suffisamment faible (de l'ordre de 2-4 kBT) pour que les fluctuations thermiques du système jouent encore un rôle important. Dans le présent travail, nous étudions le diagramme de phases du système eau/NaCL/décane/SDS/octanol. Dans ce diagramme particulièrement riche on trouve, outre des phases microémulsion extrêmement diluées, des phases présentant un ordre à longue distance (hexagonal, tétragonal, cubique ou mésophases intermédiaires) dont la taille caractéristique atteint 2000-3000 Å. Nos études, essentiellement menées par diffusion de rayonnement (rayons X et lumière), nous apportent des informations sur la symétrie de ces phases, la nature des transitions et le rôle du cosurfactant et de la température. Par ailleurs, l'étude par diffusion dynamique de la lumière des phases microémulsion met en évidence un nouveau mode de relaxation diffusif, que nous interprétons comme un mode de relaxation topologique lié à des processus de fusion du film. Nous soulignons le rôle de la courbure spontanée dans (interprétation de nos résultats.
19
Pleines, Maximilian. "Viscosity-control and prediction of microemulsions." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS139.
Повний текст джерелаАнотація:
La viscosité est une propriété fondamentale des fluides complexes et qui reste encore difficile à prédire quantitativement. Cette propriété macroscopique provient de propriétés moléculaires et mésoscopiques. La compréhension et l’estimation de l'évolution de la viscosité avec des paramètres variables est important pour plusieurs applications, entre autres pour l’extraction liquide-liquide et pour la formulation de systèmes tensioactifs aqueux.Dans ce travail, un modèle "minimal" prenant en compte les énergies libres mises en jeu a été développé pour aider à comprendre, contrôler et prédire l'évolution de la viscosité des microémulsions en présence de solutés. Le terme «minimal» signifie dans ce contexte que ce modèle est basé sur un ensemble minimal de paramètres qui sont tous mesurables ou ont une signification physique, ce qui permet d’éviter le recours à des paramètres ajustables. Ce modèle développé dans cette thèse considère les termes chimiques à l'échelle moléculaire, les termes physiques à l'échelle mésoscopique ainsi que les caractéristiques d'écoulement à l'échelle macroscopique a été appliqué sur des microémulsions pauvres en eau utilisé pour l’extraction des métaux ainsi que sur des systèmes tensioactifs anioniques aqueuxViscosity is a fundamental property of complex fluids that is still nowadays extremely difficult to predict quantitatively. This macroscopic property originates from molecular and mesoscopic properties. The understanding and prediction of the evolution of the viscosity with changing parameters is crucial for several applications, amongst others for liquid-liquid extraction processes and for formulation of aqueous surfactant systems.In this work, a “minimal” model taking into account the relevant free energies was developed that helps to understand, control and predict the evolution of the viscosity of microemulsions in presence of solutes. The term “minimal” means in that context that this model is based on a minimal set of parameters that are all measurable and have a physical meaning, thus avoiding input of any adjustable parameter. This model that considers the chemical terms at molecular scale, the physical terms at meso-scale as well as the flow characteristics at macroscale was applied on water-poor extracting microemulsions as well as on aqueous anionic surfactant systems
20
Atkinson, Peter J. "Characterisation of microemulsion-based organo-gels." Thesis, University of East Anglia, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292227.
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21
Rees, Gareth David. "Lipase catalysis in microemulsion-based systems." Thesis, University of East Anglia, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236927.
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22
Thorpe, Matthew Robert. "Microemulsion formation in 1,1,1,2-tetrafluoroethane (R134a)." Thesis, University of East Anglia, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410249.
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23
Galal, M. F. "Studies of micellar and microemulsion media." Thesis, University of Kent, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374302.
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24
Nicholson, Catherine Emma. "Crystallisation in emulsion and microemulsion systems." Thesis, Durham University, 2006. http://etheses.dur.ac.uk/1298/.
Повний текст джерелаАнотація:
The use of emulsions as an aid to the study of crystallisation has long been known. However, the exploitation of this technique has not yet been realised to its full potential. The various conditions that can be generated at, or near, an interfacial region provide a wide range of possibilities for the controL and probing of crystallisation mechanisms. In this thesis, the effect of the interfacial curvature is considered for the case of ice crystallisation within water-in-oil emulsions. The use of a known ice nucleator, heptacosanol, acting as a co-surfactant enables the effect of a reduced epitaxial match to be monitored, with decreasing water pool diameter. The extreme case where the water pool does not contain enough material to form a crystalline nucleus such that ~G ~ 0 on complete crystallisation is found. This demonstrates for the first time that a direct experimental measurement of the critical nucleus size is possible. The use of non-ionic surfactants allows emulsions to phase invert from water-in-oil to oil-in-water upon cooling, and on passing through the phase inversion, ultra low interfacial tensions are obtained. At the phase inversion, crystallisation by the surfactant layer is found to be greatly inhibited, even at high solute supersaturations for glycine and L-asparagine emulsions. Hence we achieve anomalous crystallization behaviour, with crystallisation achieved both on cooling and heating from the same system. Another unique effect characterised is that of oil droplet inclusion into a single crystal. The highly polar octanoic acid oil phase adheres to the growing glycine crystal so strongly that crystal growth proceeds around the droplet without disruption to the overall resulting crystal to produce macroporous crystals. Where growth rates are uneven, highly fenestrated single crystalline structures result. Upon reducing the oil droplet diameter, dendritic morphologies, highly unusual for such low supersaturations of glycine, are formed. Moreover, the surfactant mixture also controls the polymorph produced, and reproducibly yields the desired ~-glycine form.
25
Shoop, Brian H. "Applications of sugar-based microemulsion glasses." Cincinnati, Ohio : University of Cincinnati, 2009. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1258661949.
Повний текст джерелаАнотація:
Thesis (M.S.)--University of Cincinnati, 2009.Advisor: Chia-Chi Ho. Title from electronic thesis title page (viewed Feb. 19, 2010). Includes abstract. Keywords: Microemulsion; Sucrose Ester; Sodium Citrate; Glass; Template; Polymerization. Includes bibliographical references.
26
Girard, Nathalie Renee Claude. "Oil-in-water microemulsions and their polymerization." Thesis, Imperial College London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369502.
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Lankford, William Timothy. "The toxicity and pharmacokinetics of pyrethroid microemulsions." Thesis, Nottingham Trent University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384861.
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Aboofazeli, Reza. "The formation and characterization of phospholipid microemulsions." Thesis, King's College London (University of London), 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307045.
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Halliday, Nicola Ann. "Magnetic resonance investigations of pH in microemulsions." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1407/.
Повний текст джерелаАнотація:
The work presented in this thesis has investigated the development of magnetic resonance (MR) techniques to probe the pH in aqueous solutions and reverse micelles formed in CTAB, Triton-X and AOT microemulsions. These techniques have enabled visualisation of propagating acidity fronts in the bromate-sulfite reaction using magnetic resonance imaging. Contrast agents that are sensitive to pH were investigated in aqueous and microemulsion media. Successful magnetic resonance imaging of the aqueous system was achieved using the pH-dependent chelation of the paramagnetic species Cu(II), with the chelating ligand triethylenetetramine. However, it was found that MR contrast agents were not required for probing the pH in reverse micelles of the CTAB and Triton-X microemulsions. Magnetic resonance imaging of the bromate- sulfite reaction in a CTAB microemulsion system was achieved without the need for additional probe molecules or contrast agents and was found possible following investigations of pH in reverse micelles of the microemulsion using MR relaxation times. T_2 relaxation times of water in the CTAB and Triton-X microemulsions were found to change with pH, however, T_1 relaxation times remained unaffected. This behaviour was attributed to acid-catalysed exchange between protons of water and hydroxyl protons of the cosurfactant alcohol in these systems. These findings present the first direct monitoring of pH in reverse micelles of microemulsion systems without the need for probe molecules
30
Yan, Ci. "Surfactant films in water-in-CO₂ microemulsions." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682365.
Повний текст джерелаАнотація:
Supercritical C02 (SCC02) has attracted increasing attention as a promising alternative for volatile organic solvent s, due to its abundance, non-toxic, non-flammable, and non-hazardous properties which make C02 a strong candidate for use as a green solvent. However, SCC02 is generally a very poor solvent, especially for polar and high molecular weight solutes, which has largely limited the applications of this supercritical liquid as a processing medium. On the other hand, emulsions and microemulsions have been widely accepted as effective media to stabilize immiscible components, such as water and oil. Studies have been carried out extensively for water-in-scC02 (w/c) microemulsions over the last two decades, in particular, Small-Angle Neutron Scattering (SANS) has been recognised as a powerful technique characterise the self-assembly structures, and frequently applied to investigate such systems. In this thesis, the validity of contrast variation SANS (CV-SANS) has been examined in w/c microemulsions by employing mixtures of D20 and H20 as contrast agents. With this method, the core-shell structure of w/c microemulsions has been highlighted, which allows behaviour of the microemulsions and in particular, the properties of surfactant films to be studied in detail. In addition, a systematic study has also been conducted on the effects of amphiphilic additives known as 'hydrotropes' on surfactant films in both water-in-oil and water-in -C02 microemulsions. Based on these observations, a novel surfactant has been synthesised and applied to w/c microemulsions as an additive, which effectively triggers elongation of microemulsion droplets. This work takes significant step in both exploring the fundamental aspect of the self-assembly structures in C02, and also for the optimization of the physicochemical properties of such systems for potential applications.
31
Niemann, Björn. "Population dynamics of nanoparticle precipitation in microemulsions." Magdeburg Docupoint-Verl, 2009. http://d-nb.info/998665185/04.
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32
Yildiz, Ünveren Hesna Hülya. "Hydroformylation of long chain olefins in microemulsion." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972892109.
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33
Mutch, Kevin James. "Microemulsion-polymer mixtures in the protein limit." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500413.
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34
McDonald, J. A. "Phase behaviour and structure in microemulsion dispersions." Thesis, University of Kent, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375055.
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35
Shukla, Anuj. "Characterization of microemulsions using small angle scattering techniques." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969395817.
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Hussain, Arshad. "Phase behaviour of microemulsions for enhanced oil recovery." Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/8492.
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Krauel, Karen, and n/a. "Formulation and characterisation of nanoparticles from biocompatible microemulsions." University of Otago. School of Pharmacy, 2005. http://adt.otago.ac.nz./public/adt-NZDU20070424.130711.
Повний текст джерелаАнотація:
The aims of this study were to prepare poly (ethylcyanoacrylate) (PECA) nanoparticles on the basis of different types of microemulsions, to investigate the entrapment within and release of a bioactive from these particles and to establish a set of delivery systems with varying entrapment and release characteristics, thereby giving the formulator the opportunity of a more tailor-made approach in the development of a delivery system. Furthermore the scale up of particle preparation and the possible enhancement of the immunogenic properties of PECA particles by incorporation of the adjuvant Quil A was investigated.
Methods: Four phase triangles were established and microemulsion samples, used as a template to prepare nanoparticles, were characterised by viscosity and conductivity measurements, polarising light microscopy, freeze fracture transmission electron microscopy (TEM), cryo field emission electron microscopy (cryo FESEM) and self-diffusion NMR to determine their microemulsion type (droplet, bicontinuous, solution type). PECA nanoparticles were prepared from different types of microemulsions by interfacial polymerisation. Particle size, polydispersity index (PI) and [zeta]-potential were measured by photon correlation spectroscopy and electrophoretic mobility respectively. Normal scanning electron microscopy (SEM) and cryo FESEM were used to visualise particles. Fluorescently labelled ovalbumin (FITC-OVA) was used as a model protein/antigen and entrapment within and release from nanoparticles was investigated. To scale up nanoparticle preparation an instrumental set-up with reactor, peristaltic pump and stirrer was used. A 2⁷ fractional factorial study was designed to observe possible factors or their interactions that could influence particle formation under scale up conditions. For an immunological study freeze dried formulations of PECA nanoparticles, having FITC-OVA and Quil A entrapped, were prepared, and activation and uptake of formulations by murine bone marrow derived dendritic cells (DCs) and T cells in vitro were monitored.
Results: Results obtained from the measurements described above, for formulations from the four different phase triangles, indicated that microemulsions of w/o droplet, bicontinuous or solution type could be formed. It was possible to prepare PECA nanoparticles from all of the different types of microemulsions. Particles had an average size of 265 nm � 24, with an average PI of 0.18 � 0.05 and an average negative [zeta]-potential of -17 mV � -5. Particle size, PI and [zeta]-potential were not influenced by the type of microemulsion that was used as a polymerisation template. Entrapment and release were however influenced by the type of microemulsion and although entrapment of FITC-OVA was generally high for PECA particles, it was highest for particles prepared from a droplet type microemulsion. Entrapment could also be increased by increasing amounts of monomer. The rate of release was dependent on the amount of monomer used for polymerisation and the type of microemulsion used for particle preparation, with nanoparticles prepared from a w/o droplet type microemulsion showing the slowest release. Furthermore it was shown that particle preparation could be scaled-up with the instrumental set-up used in this study, but conditions need to be refined as the average particle size and polydispersity index were considerably larger (441 nm � 101, 0.68 � 0.14) when compared to particles prepared by the beaker-pipette method (see above). The adjuvant Quil A could efficiently be entrapped into PECA nanoparticles together with FITC-OVA. Incubation of DCs and T cells with the various formulations did, however, not result in increased uptake or activation.
Conclusions: PECA nanoparticles with high entrapment efficiency of antigen and adjuvant can be prepared from different types of microemulsions. Particles show different rates of entrapment and release depending on the type of microemulsion used as a polymerisation template, possibly because two different types of nanoparticles form. Nanocapsules are believed to form on the basis of droplet type microemulsions and nanospheres form on the basis of bicontinuous and solution type microemulsions. Freeze dried formulations of PECA nanoparticles, containing Quil A and FITC-OVA, were not able to induce an immune response, which might be due to charge repulsion effects between the negatively charged PECA nanoparticles and the negatively charged surface of dendritic cells. Moreover, no adjuvant effect of Quil A was apparent, perhaps caused by total encapsulation of the compound into the particle matrix with no active groups extending out displaying adjuvanticity.
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Hetherington, Karen J. "Properties of microemulsions formed with di-chained surfactants." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245512.
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Binks, Daniel Anthony. "Magnetic resonance studies of chemical reactions in microemulsions." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/573/.
Повний текст джерелаАнотація:
The Belousov-Zhabotinsky (BZ) reaction is the preeminent oscillating chemical reaction for the study of pattern formation in reaction-diffusion systems. The dispersal of the reaction in a water-in-oil AOT microemulsion (BZ-AOT reaction) gives rise to an extended range of patterns, including dash waves, segmented spirals and, most notably, stationary Turing patterns that are thought to be significant to an understanding of the biological process of morphogenesis. To date, these patterns have only been observed in two-dimensions using optical microscopy. In this project, nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) techniques were used along with existing optical methods in order to identify redox indicators suitable for the visualisation of pattern formation in the BZ-AOT reaction using MRI. The location of the redox indicator in the microemulsion was found to be important with respect to its application as an indicator. Thus, the use of Ru(II)(bpy)3 as an MR contrast agent was ruled out as it was found to reside within the micellar interface. Manganese, however, proved to be a viable MR indicator. Oscillations were observed in the manganese-catalysed BZ-AOT reaction through changes in the NMR relaxation times of solvent water molecules. The ability of manganese to act as an MR contrast indicator has enabled pattern formation in the BZ-AOT reaction to be visualised using MRI for the first time. Further development of the technique may allow pattern formation to be visualised in three-dimensions.
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Cook, Oliver James. "Control of crystallisation through the use of microemulsions." Thesis, Durham University, 2012. http://etheses.dur.ac.uk/7301/.
Повний текст джерелаАнотація:
Control of crystallisation is hugely important in many areas of science and technology. The size of crystals can often be crucial in how they perform. In addition the polymorphism of crystals is just as important, especially for the pharmaceutical sciences, where unexpected changes in polymorphism can spell disaster for certain drugs. With these requirements in mind, we have demonstrated that microemulsions can be used to offer thermodynamic control of crystallisation, not just with regards to polymorphism of organic crystals, but also to the synthesis of certain inorganic compounds. The polymorphism of glycine was first investigated in an attempt to grow all three polymorphs (α-, β- and γ-) at room temperature and pressure. The most stable of these, γ-glycine grows ~ 500 times more slowly than the next most stable form, α-glycine. Using microemulsions made up with the surfactant AOT, the continuous oil phase heptane and a nanoconfined aqueous glycine solution, all three polymorphs of glycine were crystallised by adding methanol dropwise under varying conditions. Non-ionic surfactant systems were also investigated, using combinations of the surfactants Span 80/Tween 80 and Span 80/Brij 30. Using the Span 80/Brij 30 system, the most stable form, γ-glycine, could be formed predominantly by mixing an aqueous glycine microemulsion with an aqueous methanol microemulsion. This proved that Ostwald’s Rule of Stages could be circumvented in order to obtain the most stable polymorph. Following this, microemulsions were used to demonstrate that inorganic crystalline materials could be synthesised in microemulsion droplets- again at room temperature and pressure. Hydroxyapatite, known as a component of natural bone, was made using Triton X-100/1-hexanol/cyclohexane microemulsions via two methods, firstly via direct addition of reactants, then again via mixed microemulsion methods. Subsequent analysis showed that the final product showed excellent correlation with bought-in hydroxyapatite (reagent grade), with regards to purity and crystallinity. Finally the synthesis of titanium dioxide nanoparticles was reported. These set of experiments brought both challenges of controlling polymorphism and synthesising materials together. Rutile – the most stable of polymorph of titanium dioxide – was synthesised as the predominant polymorph from the microemulsions. Electron microscopy studies were able to track the particle size growth between 2 and 13 nm at various times up to 18 hours after mixing the reactant microemulsions.
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Beckford, Elaine Susan. "Low frequency dielectric spectroscopic analysis of reverse microemulsions." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/low-frequency-dielectric-spectroscopic-analysis-of-reverse-microemulsions(28476252-5e4e-4c14-9d33-ce070394a5e5).html.
Повний текст джерелаАнотація:
Low frequency dielectric spectroscopy in the MHz down to 0.1 mHz range, was used to investigate and characterise ternary reverse microemulsions, micellar systems and their individual components. Anionic surfactant sodium bis (2-ethylhexyl) sulfosuccinate (AOT), oil isopropyl myristate (IPM) and deionised water were chosen as they readily form reverse microemulsions and have been investigated with other physicochemical techniques. Low frequency dielectric spectroscopy is a non-invasive technique, able to probe the electrical properties of materials without isotopic labelling. The dielectric response of the microemulsions stabilised with 20% w/w AOT displayed a small anomalous increase in the conductance and a decrease in the capacitance to negative values at frequencies below the characteristic intracluster frequency ω1, but above the commencement Maxwell-Wagner interface charging process. Spectroscopic measurements of the individual components showed IPM exhibited similar anomalous characteristics at frequencies below 1Hz. Increases in conductance are indicative of structural change, and negative capacitances have been reported to occur in animal cells such as neurons undergoing changes in membrane potential during ion flux. Hence the response of IPM displayed characteristics of biological membranes able to undergo structural changes resulting in an increased conductance in specific frequency ranges. The response of the anomalous features were fitted using the Dissado-Hill cluster model adapted to include the linearised frequency dependant conductance term G(ω). This term replaced the static conductance component in the bulk parallel conductance–capacitor pair of bulk–barrier series circuit model of the samples investigated. The anomalous features, together with the changing intracluster relaxation time τ1 were used to track the micellar to microemulsion transition as the molar concentration ratio W0=[H2O]/[AOT] was increased 0 < W0 < 26. The presence of microemulsion aggregates indicated by the slowing down of the τ1 response time at W0 > 9 was confirmed by the detection of particles with radii 12 to 29 nm using light scattering.
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Zheng, Guanyu. "Bioremediation of organochlorine pesticides contaminated soil with microemulsions." HKBU Institutional Repository, 2011. http://repository.hkbu.edu.hk/etd_ra/1245.
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Nonaka, Gen. "Behavior and Utilization of Sodium Dioleyl Phosphate Microemulsions." Kyoto University, 1999. http://hdl.handle.net/2433/181683.
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O'Donnell, Jennifer M. "Reversible addition-fragmentation chain transfer in microemulsion polymerizations." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 218 p, 2007. http://proquest.umi.com/pqdweb?did=1354135141&sid=45&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Carlile, Katherine. "Lipase-catalysed reactions in W/O microemulsion systems." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267466.
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Price, Ann Louise. "Characterisation of Ni(AOT)â†2 microemulsion systems." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389224.
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Katsikides, Andrew. "Phase behaviour structure and dynamics of microemulsion systems." Thesis, University of Kent, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329298.
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Khan-Lodi, A. N. "Microparticle synthesis and colloidal catalysis in microemulsion media." Thesis, University of Kent, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234057.
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Lee, Daniel Dongyuel. "Interfacial properties of surfactant monolayers in microemulsion systems." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/33538.
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Lopian, Tobias. "Characterization of a metal-extracting water-poor microemulsion." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT206/document.
Повний текст джерелаАнотація:
Le recyclage des terres rares à partir de déchets électroniques n'a toujours pas trouvé une réalisation industrielle significative. L'une des raisons est le manque de procédures de séparation optimisées en raison de connaissances fondamentales médiocres sur ces systèmes. En raison des similitudes chimiques et physiques de ces métaux, la conception d'une formulation efficace, adaptative et prédictive est toujours hors de portée des possibilités. L'interprétation supramoléculaire de la formation complexe dans la phase organique est de plus en plus importante au cours des dernières années. C'est l'approche la plus prometteuse permettant l'explication de divers phénomènes, tels que la formation de la troisième phase et les signaux forts dans de petites expériences de diffusion et de revenir à des méthodes bien connues de la science des tensioactifs. Notre contribution à une compréhension plus complète dans cette matière est l'analyse du comportement électrodynamique de ces phases et la corrélation de ces résultats avec les résultats des propriétés d'auto-assemblage et du transport de masse dans ces médias. Pour cette étude, nous avons spécifiquement conçu un modèle de référence, en passant un processus d'extraction à ses quatre composants fondamentaux: l'extracteur avant l'extraction (acide Di-(2-éthylhexyl) phosphorique, HDEHP), l'extrait après extraction (son sel de sodium, NaDEHP ), le toluène comme diluant apolaire et de l'eau. Un prisme de phase de Gibbs a été préparé (illustré sur la figure 1), où l'axe z donne le rapport de HDEHP à NaDEHP, ce qui représente le développement d'une extraction. Couvrant le domaine de basse fréquence, la spectroscopie d'impédance a été la méthode de choix afin de déterminer la conductivité dépendant de la fréquence. En utilisant la spectroscopie de relaxation diélectrique, nous révélons des processus dynamiques rapides à haute fréquence. Des mesures combinées SAXS et SANS ont été effectuées pour comparer les tendances électrodynamiques avec les propriétés d'agrégation et les interactions entre groupes. Deux phénomènes ont été identifiés comme responsables du profil de conductivité dans les systèmes micellaires inverse: la formation d'agrégats chargés par la dissimulation et la percolation. Tout au long du système de référence, ces deux processus ont été sondés en fonction de trois variables: la concentration totale d'agent d'extraction, le rapport eau-agent tensioactif et le rapport Na: H. En tant que résultat majeur, l'eau joue un rôle important dans les deux processus. En cas de percolation, les agrégats inverse ne peuvent pas fusionner en l'absence d'eau. Par conséquent, la conductivité électrique est interdite. Dans les systèmes dilués, l'eau facilite le processus de dismutation, entraînant une augmentation de la conductivitéRecycling of rare earths from electronic waste has still not found a significant industrial realization. One reason is the lack of optimized separation procedures due to poor fundamental knowledge on these systems. Due to the chemical and physical similarities of these metals, designing an efficient, adaptive and predictive formulation is still out of scope of possibilities. The supramolecular interpretation of complex-formation in the organic phase has gained an increasing importance in the last years. It is the most promising approach allowing the explanation of diverse phenomena, such as third phase formation and strong signals in small scattering experiments and to revert to methods well known from surfactant science. Our contribution towards a more complete understanding in this matter is the analysis of the electrodynamic behaviour of such phases and the correlation of these findings with the results of self-assembly properties and mass transport in these media.For this study, we specifically designed a reference model, breaking an extraction process down to its four fundamental components: The extractant before extraction (Di-(2-ethylhexyl)phosphoric acid, HDEHP), the extractant after extraction (its sodium salt, NaDEHP), toluene as apolar diluent and water. A Gibbs phase prism has been prepared (illustrated in Figure 1), where the z-axis gives the ratio of HDEHP to NaDEHP, representing the development of an extraction. Covering the low frequency-domain, impedance spectroscopy has been the method of choice in order to determine the frequency-dependent conductivity. Using dielectric relaxation spectroscopy, we reveal fast dynamic processes at high frequencies. Combined SAXS and SANS measurements have been performed to compare the electrodynamic trends with aggregation properties and intercluster interactions.Two phenomena have been identified to be responsible for the conductivity profile in reverse micellar systems: the formation of charged aggregates through dismutation and percolation. Throughout the reference system, these two processes have been probed as function of three variables: total extractant concentration, the water-to-surfactant ratio and the Na:H-ratio. As a major result, water plays a significant role in both processes. In case of percolation, reverse aggregates are not able to merge in the absence of water. Therefore, electrical conductivity is prohibited. In dilute systems, water facilitates the dismutation–process leading to an increase in conductivity