To see the other types of publications on this topic, follow the link: Reversed micelle.
Dissertations / Theses on the topic 'Reversed micelle'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Reversed micelle.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Sinha, Kaustav. "Approach to develop reverse micelle large-scale synthesis process for magnetic nanopowders /." abstract and full text PDF (free order & download UNR users only), 2005. http://0-wwwlib.umi.com.innopac.library.unr.edu/dissertations/fullcit/1433113.
Full textAbstract:
Thesis (M.S.)--University of Nevada, Reno, 2005."August, 2005." Includes bibliographical references. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2005]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
2
Bandyopadhyaya, Rajdip. "Modelling Of Precipitation In Reverse Micelles." Thesis, Indian Institute of Science, 1999. http://hdl.handle.net/2005/145.
Full textAbstract:
Nanoparticles have important applications in ceramics, metal catalysts, semiconductors etc. They are normally required to be of small size (~ nm) and monodisperse. The aim of the present work is to model the formation of nanoparticles, obtained by precipitation in reverse micellar microreactors. These are dispersions of tiny water drops in a surfactant laden oil medium. Two systems were investigated: (i) Reverse micelles, having nanometer sized spherical water droplets in the micellar core and (ii) Water-in-oil emulsions, having micron-sized aqueous drops. Two modes of precipitation, namely, gas-liquid (g-1) and liquid-liquid (1-1) were studied. In each case, the models could predict the number, average size and size distribution of the particles reported in literature.
Two groups have obtained widely divergent number and size of CaCO3 nanoparticles, formed by g-1 precipitation in reverse micelles. These particles are used as a fine suspension in lube-oil additives, where they serve to neutralize acid produced during combustion in engines. Kandori et al. (J. Colloid Interface Sci, 122,1988, 78) obtained particles of about 100 nm size, by passing CO2 through a reverse micellar solution, containing dissolved Ca(OH)2 in the micellar core. Roman et al. (J. Colloid Interface Sci., 144,1991, 324), instead of using lime solution; added micron-sized solid lime particles in the oil and generated the reverse micelles by in situ reaction. This is a commercial process known as overbasing. It led to a higher amount of lime in the micelles as well as unreacted lime particles in oil, at the beginning of the experiment Upon passing CO2, they got particles of only 6 nm in size, compared to 100 nm reported by Kandori et al.. Furthermore, while Kandori et al. found that one particle formed from 108 micelles, Roman et al. got one particle out of only ten micelles.
We have modelled the two processes in a common framework to explain the reported disparity in particle characteristics. A time scale analysis of CO2 mass transfer, reaction, collision-fusion of micelles, nucleation, and growth of particles was carried out It showed that, in the experiments of Kandori et al., the rate limiting steps are nucleation and fusion. The analysis also indicates that the contents of a particular micelle are well mixed and reaction of lime and incoming CO2 can be treated as instantaneous. In the process of Kandori et al., the amount of lime taken initially being very small, the average number of product molecules in a micelle is well below one. Rapid Brownian coalescence and exchange of micellar contents leads to Poisson distribution of CaCO3(l) molecules formed by reaction. The low occupancy therefore suggests that most of the micelles are empty. Nucleation in a particular micelle is much slow and occurs when it has a critical number of molecules. Thus only very few micelles can nucleate. Comparison of nucleation and growth time scales - both intrinsic growth in a micelle and growth during fusion of nucleated and non-nucleated micelles - show that growth is much faster than both nucleation and collision. Hence a micelle can have only one nucleus, with subsequent growth during collisions. A population balance equation (PBE) is written involving the above steps. Solution of the moments of the distribution yields the number of CaCO3 particles, its size, coefficient of variance (COV) etc. The model not only predicts the ratio of number of micelles to particles, obtained experimentally as 108, but also captures the maxima in this quantity with increasing micellar size. The increase in average particle size with micellar size is also predicted well.
The process of of Roman et ai, in addition, involves the time scale of solubilization of solid lime into micelles. Its comparison with other time scales demarcates their experiments into two distinct phases. Phase I consists of reaction of lime initially present in micelles. Time scale analysis also suggests that, as the lime content in the micelles is large, a high degree of supersaturation is rapidly generated. This results in a burst of nuclei. The other conclusions, like, well-mixed micelle, Poisson distribution of CaCO3(l) molecules, instantaneous growth and mono-nucleated micelles are found to hold good. Once the pre-existing lime is finished, relative time scales indicate that, further precipitation is controlled entirely by fresh solubilization of lime. This marks the beginning of phase II. However, solubilization being the slowest step, CaCO3(l) in micelles never builds up for any further nucleation. Phase II thus consists of pure growth of the particles formed in phase I. On developing more general PBEs and with solution of resulting moment equations - written separately for the two phases - the experimental data on number of particles and temporal evolution to the final particle size of 6 nm could be predicted very well. The model also captures the qualitative trend in COV of particle radius with time.
Thus within the same framework we could successfully predict both the results, differing by seven orders of magnitude. The above analysis indicates that relative rates of nucleation, fusion-growth and mass transfer of gas controls the carbonation process. We further simplify the process and obtain an analytical solution in the limit of instantaneous mass transfer. The solution gives close first estimates for both the experiments and also indicates the smallest panicle size that could be obtained for a given experimental condition.
In contrast to g-1 mode, precipitation in 1-1 mode - using two reverse micellar solutions having two reactants- occurs only on coalescence of two micelles. To obviate the solution of multivariate PBEs, we have developed a general Monte Carlo (MC) simulation scheme for nanoparticle formation, using the interval of quiescence technique (IQ). Starting with a fixed number of micelles, we conduct each coalescence-redispersion and nucleation events in this population, in the ratio of their relative frequencies. Our simulation code is much more general and realistic than the scheme of Li and Park (Langmuir, 15,1999, 952). Poisson distribution with realistic micellar occupancies of reactants, binomial redispersion of solutes after fission, a nucleation rate with critical number of molecules and Brownian collision-fusion rates were used. These considerations are based on our earlier findings in g-1 precipitation and those known in the literature too. The simulation of Li and Park then becomes a special case of our code. Our simulation code was then used to predict experimental data on two systems. The results of Lianos and Thomas (Chem. Phys. Lett. 125, 1986, 299 and /. Colloid Interface 5c/., 117, 1987, 505), on number of molecules per CdS particle, as a function of micelle size and reactant concentrations have been predicted very well. For the Fe(OH)3 nanoparticles, our simulation provides a better prediction of the experimental particle size range, than that of Li and Park.
Finally, 1-1 precipitation on mixing two emulsions, having respectively the two reactants, has been simulated. Here, large reactant amount leads to multiple nucleation in a single drop and renders growth rate to be finite. This requires solving a PBE for particle population in each drop. Moreover, emulsions have a drop size distribution due to independent coalescence and breakage. The IQ technique was used for handling these events. Thus a composite model of PBE and MC for a drop population was developed. Simulation of particle size distribution in MgCO3 precipitation shows that nearly monodisperse nanoparticles can be produced in emulsions. Furthermore, average particle size can be controlled by changing reactant concentration in a drop.
The findings of the thesis have provided new issues to be addressed in modelling nanoparticle formation. It points out the importance of finding models for coalescence efficiency and critical nuclear size in micelles. Extension of our model and simulation to precipitation in other organized surfactant assemblies can be done by starting from appropriate time scale analysis.
3
Petit, Christophe. "Relation entre structure et reactivite en micelles inverses d'aot." Paris 6, 1988. http://www.theses.fr/1988PA066473.
Full textAbstract:
Les micelles inverses d'aerosol ot sont des muroemulsions eau/huile dont la taille est controlee par la quantite d'eau solubilisee. La solubilisation des petites molecules ainsi que des petites proteines entrainent des perturbations dans la structure et la reactivite. Un modele de localisation des sondes en micelle est propose a partir des mesures de structure, par diffusion des rayons x, et de reactivite par radiolyse pulse. De plus, une synthese in situ des semiconducteurs en micelle inverse est exposee
4
Brochette, Pascal. "Reactivite en micelles inverses." Paris 6, 1987. http://www.theses.fr/1987PA066087.
Full textAbstract:
En utilisant l'electron hydrate comme sonde intramicellaire, etude du comportement de l'eau au sein des microphases aqueuses, et du transfert d'electron de la chlorophylle vers des viologenes dans la microemulsion
5
Alexandridis, Paschalis. "Thermodynamics and dynamics of micellization and micelle-solute interactions in block-copolymer and reverse micellar systems." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37749.
Full text
6
Ladanowski, Caroline. "Separation with reverse-micelles." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60587.
Full textAbstract:
Reverse-micelles are surfactant aggregates in an apolar solvent. The surfactants, which must have two hydrophobic tails, cluster around a water core. The effects of the compositions of the solvent and the aqueous phase on water solubilization were studied for two anionic surfactants: sodium di-2-ethylhexylsulfosuccinate (AOT) and dinonylnaphthalene sulfonic acid (DNNSA). Single straight chain alkanes having 6-17 carbons, mixtures of these alkanes and branched alkanes were used as solvents. The aqueous phases consisted of salts and buffers.For AOT in straight chain alkanes, water uptake increased as the length of the chain approached 9 carbons, the length of the AOT hydrocarbon tail. As the solvent length increased further, a critical carbon number was reached above which there was no water uptake. Different buffers shifted the critical carbon number somewhat. Mixtures of straight chain alkanes behaved similar to single alkanes when compared on the basis of volume-average carbon number. Branched alkanes solubilized more water than their straight chain isomers. For DNNSA the water uptake was the same for all solvents.
7
Bardez, Élisabeth. "Relation entre structure et reactivite acido-basique de l'eau incluse dans les micelles inverses." Paris 6, 1987. http://www.theses.fr/1987PA066033.
Full text
8
Ashrafizadeh, Seyed Nezameddin. "Cation exchange with reverse-micelles." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61109.
Full textAbstract:
Experimental and theoretical studies on the extraction of the cation K$ sp+$ and Mg$ sp{++}$ from a bulk aqueous phase to an organic phase using the water/dinonylnaphthalene sulfonic acid (HD)/heptane reverse-micellar system was conducted. The counter ion of the surfactant, H$ sp+$, was exchanged with the alkali metal cations in the aqueous phase. Two different types of experiments were conducted. The first set involved a constant total normality of ions while the second investigated the effect, of varying the normality of ions. Electrolyte solutions with molarities ranging from 0 to 1 were contacted with a reverse-micellar organic containing different concentrations of surfactant with different types of counter ions.The HD reverse-micellar extraction system exhibited behavior similar to that of conventional ion-exchange resin systems. A preferential extraction for Mg$ sp{++}$ over K$ sp+$ was observed. The efficiency of the extraction was high for low salt concentrations and it was independent of surfactant concentration. The amount of water uptake was low, with W$ sb{o}$ ranging between 4 and 10. For a wide range of salt and surfactant concentrations W$ sb{o}$ was independent of surfactant concentration. The HD surfactant showed a low solubility in the aqueous phase.
The results of the equilibrium partition experiments were correlated using a thermodynamic model. Interaction parameters determined from binary system experimental data were used to predict the ternary system partition behavior. The ternary system predictions were compared with experimental results and found to be satisfactory.
9
Pham, Thi Minh Hai. "Protein extraction using reverse micelles." Thesis, University of Greenwich, 2015. http://gala.gre.ac.uk/18122/.
Full textAbstract:
Reverse micelles are self-organized aggregates formed by a surfactant in a non-polar solvent or oil. The presence of a water pool in the polar core of reverse micelles is of considerable advantage in protein extraction. A lot of researches have been done with ionic reverse micelles applied in protein extraction. However, this ability of non-ionic reverse micelles has not been fully understood and therefore requires more research. In this project, different surfactants (anionic AOT, cationic CTAB, non-ionic triblock L61 copolymer) were investigated for their ability to form RM and for their application in protein extraction. It was found that lysozyme could be extracted using an AOT RMS, but not with a CTAB RMS. For the first time, an aromatic solvent, p-xylene, was used for the extraction of lysozyme and it was found that the AOT in p-xylene RM system resulted in the higher lysozyme activity (73.81 %) compared to an AOT/isooctane RM system (43.2 %). The effect of different salts (KCl, KF, KBr) on the FE and BE of BSA was investigated using the CTAB in mixture of 1-bromooctane, 1-hexanol and petroleum ether. The results indicated that KCl gave the highest extraction efficiency of 64 % as compared to around 40 % with both cases of KF and KBr. The secondary structure of extracted BSA was maintained with KCl only. L61 pluronics polymers was investigated for its reverse micelles forming ability and it was established that small reverse micelles with a maximum W0 of 4 was formed. Because of the small size of L61 reverse micelles, lysozyme could not be extracted but was precipitated out when combined with the co-surfactant AOT. The activity of the recovered lysozyme from the precipitate was maintained (66% as compared with native lysozyme). Moreover, if L61 was used as a co-surfactant with AOT reverse micelles, extraction efficiency was improved (88 %) and the activity of the extracted ly-sozyme was increased (56 %) as compare to extraction with an AOT system alone (46 %). These studies thus gives useful insights in the role of individual and mixed surfactant systems in the extraction and precipitation of proteins.
10
Gunther, Selina Lavinia. "Polypeptide extraction using reverse micelles." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5529.
Full textAbstract:
The reverse micelle (RM) extraction of human IgG4 monoclonal antibodies (MAbs), humanized IgG4 MAb B72.3 Fab fragments and horse heart cytochrome-c was investigated. The effects of system parameters on forward (FE) and backward (BE) extraction was examined, and optimal extraction conditions were determined. Sodium bis(2-ethylhexyl)sulfosuccinate (AOT), bis(2-ethylhexyl)phosphate (HDEHP), isooctane and corn oil were the model surfactants and solvents. Precipitate formation was investigated, and non-ionic (polyoxyethylene(4) lauryl ether i.e. Brij 30) and counterionic (trioctylmethylammonium chloride i.e. TOMAC) surfactants were assessed to reduce precipitate formation and increase extraction yields. Protein in the precipitate was measured using acetone precipitation. Conventional RM extraction of IgG4 for AOT- and HDEHP-isooctane resulted in yields of up to 99% FE, 58% BE for AOT-isooctane, and 92% BE for HDEHP-isooctane. It was found for AOT-isooctane with TOMAC for cytochrome-c 81% FE and 98% BE; and 41% FE and 85% BE for AOT-isooctane with Brij 30 and TOMAC, 56% FE and 71% BE for AOT-corn oil, 62% FE and 89% BE for HDEHP-isooctane, and 57% FE and 59% BE for HDEHP-corn oil with TOMAC for Fab fragments. Hollow fibre membrane (HFM) extraction of cytochrome-c resulted in complete FE and 40% BE with TOMAC; and with Fab fragments resulted in 99% FE and 79% BE for AOT, and in 88% FE and 46% BE for HDEHP with Brij 30. HFM FE using two aqueous phases showed that the quantity of Fab fragments adsorbed to the membrane surface and/or stuck in the membrane pores were negligible. Structural analysis revealed that precipitate formation during HFM module extraction was not an issue compared to conventional FE, where it structurally damaged and prevented the Fab fragments and MAbs from successfully transferring into the RM phase. RM phase water content analysis from both extraction methods confirmed that RM extraction was successful.
11
Mohd-Setapar, Siti H. "Reverse micelle liquid-liquid extraction of a pharmaceutical product." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/36143.
Full textAbstract:
Reverse micelle extraction has received considerable attention in recent years due to its ability to selectively solubilise solutes from an aqueous phase, and in the case of biomolecules to maintain their biological activities, This thesis reports the results from studies on the extraction of penicillin G from aqueous solution (forward extraction) and from the reverse micelle to a new aqueous solution (backward extraction), The extraction is influenced by the initial penicillin G concentration, the salt type and concentration in the aqueous phase, pH, and surfactant concentration. The results show that penicillin is an interfacially active compound that interacts with AOT, with the interfacial association being dependent on both pH and surfactant concentration. When the penicillin to surfactant concentration ratio [P]aq/[S] is high precipitation of the penicillin occurs. The distribution coefficient favours transfer of the penicillin into the reverse micelle at moderate AOT concentrations.
12
Baker, Michelle K. "The extraction of cytochrome c and DsRed2 into reverse micelles /." Full text available online, 2009. http://www.lib.rowan.edu/find/theses.
Full text
13
Doolittle, John William. "Synthesis of microporous faujasitic zincophosphates in novel environments." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1116983708.
Full textAbstract:
Thesis (Ph.D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xxiii, 248 p.; also includes graphics. Includes bibliographical references (p. 226-248). Available online via OhioLINK's ETD Center
14
Castagnola, Mario J. "Crystal nucleation of Zincophosphate open frameworks in Reverse Micelle Nanoreactors /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488186329503551.
Full text
15
Attwood, D. "Metal ion catalysed ester hydrolysis in reverse micelles." Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234927.
Full text
16
Rocha, Júlio Cézar Barbosa. "Estudo da formação de micelas reversas do copolímero tribloco (EO13PO30EO13) em p-xileno: efeito da adição de solução salina." Universidade Federal de Viçosa, 2012. http://locus.ufv.br/handle/123456789/4254.
Full textAbstract:
Made available in DSpace on 2015-03-26T13:35:17Z (GMT). No. of bitstreams: 1
texto completo.pdf: 2299113 bytes, checksum: b733c6bace2740290d2c97582cadca54 (MD5)
Previous issue date: 2012-02-15Fundação de Amparo a Pesquisa do Estado de Minas Gerais
Triblock copolymer (EO13PO30EO13) in p-xylene and small amounts of water forms various self-organized structures, one of which are the reverse micelles. Reverse micelles are a type of self-organized system that forms in solutions and interfaces. Reverse micelles can be used in the extraction of amino acids or as nanoreactors for the synthesis of nanoparticles. In this work, reverse micelles were produced by (EO13PO30EO13) the triblock copolymer in p-xylene at concentration of 15% w/w in the presence of water or 0.1 M aqueous solutions of cadmium chloride, sodium nitroprusside, sodium sulfide, sodium hydroxide, lithium sulfate and tetra methyl ammonium chloride. We evaluated the scattered intensity and hydrodynamic diameter in different amounts of water or salts by the techniques of static and dynamic light scattering, respectively. There was an increase in the hydrodynamic diameter in the presence of all salts in comparison with that of water. The scattered intensity also increased for all salts, except for the micelles with tetra methyl ammonium chloride. We measured the variation of the refractive index of solution of 15% w/w (EO13PO30EO13) in p-xylene with different amounts of water or aqueous solutions and compared to with solution of 15% w/w (EO13PO30EO13) without amounts of water or aqueous solutions. The variation of refractive index indicated the point of formation of reverse micelles for some salts, which was not possible to determine using light scattering, and the transition point in the form of reverse micelles from spherical to ellipsoidal. In addition to the scattering experiments, microcalorimetric measurements of the reverse micelles systems were carried out using the Isothermal Titration Calorimetry technique. The results showed that the enthalpy of mixing has changed from exothermic (micelles with water) to endothermic (micelles with salt) for very low water content. In addition, reverse micelles with tetra methyl ammonium chloride and sodium hydroxide showed enthalpy of mixing much smaller in magnitude than the reverse micelles with other salts or water. For the low aqueous solution content inside the reverse micelles the endothermic enthalpy of mixing indicates that the process of desolvation of salts by molecules of water and the interaction of salts and water with the EO segments happens with cost of energy. Nuclear magnetic resonance spectra of hydrogen of the molecules of water showed the formation of free water and bound water inside the reverse micelles. The chemical shift curves increased slightly in the presence of all salts. The relaxation spin-spin of hydrogens of groups CH3 decrease with the increase of water or aqueous solution content. This was interpreted as the passage of molecules of (EO13PO30EO13) from the form of free chain to the form of reverse micelles. The value of relaxation of groups CH2 did not show significant change with the increase of water or aqueous solution content. Measurements of the relaxation of the water molecules inside the reverse micelles were made and it was determined the relaxation constant T2 of the molecule of water in the macroscopic water phase and inside the reverse micelles. The value of T2 decreases from 3.2 seconds in the macroscopic phase to a few microseconds in the inside of reverse micelles. The presence of salt in the inside of reverse micelles induced a more significant decrease in the value of T2 of molecules of water than when there was only water inside the reverse micelles.
O copolímero tri-bloco (EO13PO30EO13) em p-xileno e com a adição de água forma diversas estruturas auto-organizadas, uma das quais são as micelas reversas. As micelas reversas são um tipo de sistema auto-organizado que se forma em soluções e interfaces. As micelas reversas podem ser usadas na extração de aminoácidos ou como nanorreatores para a síntese de nanopartículas. Nesse trabalho, micelas reversas foram produzidas pelo copolímero tri bloco (EO13PO30EO13) em p-xileno na concentração de 15% m/m com adição de água ou soluções aquosas 0,1 M de cloreto de cádmio, nitroprussiato de sódio, sulfeto de sódio, hidróxido de sódio, sulfato de lítio e cloreto de tetrametilamônio. Foram avaliados a intensidade espalhada e o diâmetro hidrodinâmico em diferentes quantidades de água ou solução aquosa 0,1 M, pelas técnicas de espalhamento estático e dinâmico de luz, respectivamente. Observou-se o aumento do diâmetro hidrodinâmico na presença de todos os sais em comparação com a água. A intensidade espalhada também aumentou para todos os sais, exceto para as micelas com cloreto de tetrametilamônio. Foi medida a variação do índice de refração para a solução com 15% m/m de copolímero (EO13PO30EO13) em p-xileno com diferentes quantidades de água ou soluções aquosa e comparada com a solução de 15% m/m de copolímero (EO13PO30EO13) sem a adição de água ou solução aquosa. A variação do índice de refração indicou o ponto de formação das micelas reversas com água e com os sais cloreto de cádmio e cloreto de tetrametilamônio, que não foi possível determinar com as medidas de intensidade espalhada. Além disso foi possível determinar o ponto de transição na forma das micelas reversas de esféricas para elipsoidais para todos os sais. Complementando as medidas de espalhamento de luz foram feitas medidas energéticas do sistema de micelas reversas usando a técnica de microcalorimetria isotérmica de titulação. As medidas microcalorimétricas mostraram que a entalpia de mistura mudou de exotérmica (micelas com água) para endotérmica (micelas com solução salina) nas primeiras adições. Além disso, micelas reversas com o cloreto de tetrametilamônio e hidróxido de sódio apresentaram entalpia de mistura muito menor em módulo do que as micelas reversas com os outros sais ou água. Em baixos conteúdos de água a entalpia de mistura endotérmica indica que o processo de desolvatação dos sais pelas moléculas de água e a interação dos sais e água com os segmentos EO ocorre com gasto de energia. Espectros de resonância magnética nuclear dos hidrogênios da molécula de água mostraram a formação de água livre e água ligada no interior das micelas reversas. As curvas de deslocamentos químicos aumentaram levemente na presença de todos os sais. Ocorreu uma redução da constante relaxação spin-spin dos prótons dos grupos CH3 da molécula de L64 com o aumento do conteúdo de água ou solução salina. Esse resultado foi interpretado como a passagem de moléculas do copolímero (EO13PO30EO13) da forma de cadeia livre para a forma de micelas reversas. Já as medidas dos grupos CH2 mostraram que a relaxação spin-spin não variaram significativamente com a quantidade de água ou solução salina. As medidas de relaxação das moléculas de água no interior das micelas reversas foram feitas e foi determinada a constante de relaxação T2 da molécula de água em fase macroscópica e no interior das micelas reversas. O valor de T2 diminui de 3,2 segundos em fase macroscópica para dezenas de milisegundos no interior das micelas reversas. A presença do sal no interior das micelas reversas induziu uma diminuição mais acentuada no valor de T2 das moléculas de água do que quando havia apenas água no interior das micelas reversas.
17
Francois, Adou Yedes Akpa. "Filtration removal of reverse micelle humic substances using a polypropylene medium." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150283.
Full text
18
Bueno, Vânia Aparecida Blasques. "Produção de hidrogéis micro e nanoestruturados." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/46/46135/tde-14102010-142141/.
Full textAbstract:
Hidrogéis (redes poliméricas tridimensionais capazes de absorver grandes quantidades de água) micro e nanoestruturados têm grande potencial como biomateriais em aplicações tais como dispositivos de liberação de fármacos e agentes embólicos. Neste trabalho foram estudadas técnicas de produção desses hidrogéis micro e nanoestruturados à base de poli(N-vinil-2-pirrolidona) (PVP), a partir da reticulação do polímero através de reações de Fenton, foto-Fenton e fotólise direta. Microgéis de PVP foram obtidos a partir da reticulação de esferas obtidas por eletropulverização ou de gotículas de solução aquosa do polímero em emulsão a/o. No primeiro caso, obtiveram-se partículas que, quando reticuladas com a reação de Fenton durante o processo de eletropulverização, apresentaram formato indefinido. No segundo caso, foram obtidas microesferas de PVP, tanto pela reticulação com a reação de Fenton, obtendo-se partículas menores da - ordem de 1 µm - como com a reação de foto-Fenton, que gerou partículas maiores de - 34 µm. Hidrogéis sub-micrométricos foram obtidos a partir da formatação em vesículas de lecitina e reticulados por meio da reação de foto-Fenton. Essas vesículas foram capazes de encapsular grande quantidade de polímero, mesmo sendo este de alta massa molar média. Os hidrogéis sintetizados apresentam estreita distribuição de diâmetro, porém sem forma definida e com baixo índice de intumescimento. Por fim, nanogéis (nanopartículas de hidrogéis) foram obtidos da reticulação de PVP com a reação de Fenton (Fe2+ na presença de H2O2), utilizando como sistema formatador o interior aquoso de micelas reversas de CTAB. Os nanogéis assim formados são esféricos e apresentam propriedades interessantes, como fator de intumescimento de até 6000, inédito na literatura, que os colocam na categoria de hidrogéis superabsorventes. Além disso, o intumescimento é passível de controle tanto pela remoção dos íons Fe3+ complexados, como pela acidez e composição iônica do meio. Durante o desenvolvimento da síntese dos nanogéis foi possível estudar a influência do Fe3+ na estruturação da solução polimérica e do hidrogel. Além disso, a cinética da reticulação do polímero dentro das micelas e uma comparação entre dois sistemas micelares diferentes na formatação do nanogel foram analisados. A análise do produto também permitiu constatar a baixa toxicidade do material obtido com testes in vitro utilizando macrófagos e fibroblastos.Micro and nanostructured hydrogels (three-dimensional polymeric networks capable of absorbing large amounts of water) have great potential as biomaterials in applications such as drug delivery devices and embolic agents. In this work techniques to produce micro and nanostructured hydrogels from poly(N-vinyl-2-pyrrolidone) (PVP) were studied from various crosslinking reactions like Fenton, photo-Fenton and direct photolysis. PVP microgels were obtained from crosslinking of polymer spheres obtained by electrospraying a polymer solution or from droplets of aqueous polymer solution in w/o emulsion. In the first case, particles were obtained that, when crosslinked with the Fenton reaction, showed undefined morphology. In the second case, spherical PVP hydrogel microparticles were obtained, which were formed by crosslinking with Fenton reaction, resulting in smaller particles - about 1µm - while with photo-Fenton reaction it generated larger particles - about 34 µm. Sub-micrometric hydrogels were obtained from lecithin vesicles as formatting system through crosslinking with photo-Fenton reaction. These vesicles were able to encapsulate large amounts of polymer, in spite of its high average molecular weight. Hydrogels synthesized by this method are formless, with narrow diameter distribution and low swelling properties. Finally, nanogels (hydrogel nanoparticles) were obtained from crosslinking of PVP by the Fenton reaction (Fe2+ in presence of H2O2), using aqueous pool of CTAB reverse micelles as formatting system. The thus formed nanogels are spherical and present interesting properties such as swelling ratio of 6000, a level unreported in literature, which classifies them as superabsorbent hydrogels. Moreover, the swelling is susceptible to control either by the removal of complexed Fe3+ ions or by acidity and ionic composition of the medium. During the nanogels synthesis development, the influence of Fe3+ in the arrangement of the polymer solution and of the hydrogel was studied. Morever, the polymer crosslinking kinetics inside the micelles and a comparison between two different micellar systems in formatting of nanogel were analyzed. The product analysis also revealed low toxicity of the obtained material by in vitro experiments using macrophages and fibroblasts.
19
Mall, Sanjay. "Studies on the transfer and refolding of lysozyme in reversed micelles." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319203.
Full text
20
Duangchan, Apinya. "Residue upgrading using dispersed catalysts prepared in reverse micelles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq27133.pdf.
Full text
21
Miletti, George. "Surfactant partition and water solubilization in reversed micellar systems." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59415.
Full textAbstract:
A reversed micellar phase was studied using infrared spectroscopy and surface tension analysis. The effect of the organic phase composition and the type and concentration of salt were investigated. Two parameters were measured, the surfactant partition between the organic and aqueous phases and the amount of water solubilized. The organic phase consisted of a mixture of hexane and hexadecane containing dissolved Aerosol OT. The aqueous phase contained a postassium salt in a buffer solution.The Aerosol OT partitioned essentially completely to the organic phase under conditions of high salt concentration or high hexane concentration. As the hexane:hexadecane ratio increased, the amount of water solubilized decreased. For all salts, except those of lanthanum, the water solubilized decreased considerably as the salt concentrations increased.
22
Gardner, Adam R. "Molecular dynamics of aot/water/isooctane reverse micelles dynamic and structural analysis and effect of zirconium ions on the micelles structure for ZrO2 nanoparticle production /." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1442844.
Full text
23
Corral, Jessica Olga. "Preparation of rare-earth (Eu3+, Tb3+, and Yb3+) doped Y2O3 luminescent ceramics by the use of reverse micelles." abstract and full text PDF (free order & download UNR users only), 2004. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1434067.
Full text
24
Lye, Gary James. "Kinetic studies on the extraction of proteins using reverse micelles." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357143.
Full text
25
Kitchens, Christopher Lawrence Roberts Christopher B. "Metallic nanoparticle synthesis within reverse micellar micromulsion systems." Auburn, Ala., 2004. http://repo.lib.auburn.edu/EtdRoot/2004/FALL/Chemical_Engineering/Dissertation/kitchcl_13_Dissertation(abbrv).pdf.
Full text
26
Clarkson, Ian Michael. "Energy transfer in lanthanide complexes." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4498/.
Full textAbstract:
This thesis details investigations into the photophysical properties of lanthanide ions in a number of different systems. The preparation and characterisation of lanthanide containing surfactant salts of the type Ln(A0T)(_3) (Ln = Tb, Nd, Eu, AOT = bis-(2-ethylhexyl) sulfosuccinate) is described. Small angle neutron scattering experiments have been used to determine the size and shape of reverse micelles formed by these surfactants in water/cyclohexane microemulsions. The luminescence lifetimes of the lanthanide ions have been used to investigate the solvation environment within reverse micelle systems as a function of water content. The use of lanthanide complexes based on 1,4,7,10-tetraazacyclododecane bearing phenanthridine antenna in luminescence microscopy has been explored. Samples such as silica particles, onion skin cells and guinea pig heart cells have been imaged. Time- resolved measurements have allowed time gating of the sample from a fluorescent background and lifetime maps of the images have been obtained. The preparation and characterisation of deuteriated complexes of dota (1,4,7,10- tetraazacyclododecane-1,4,7,10-tetraacetic acid) with lanthanide ions is described. Selective deuteriation of both the ring and arm sites allow the relative quenching effects of C-H/D oscillators to be determined for various lanthanides in a series of structurally well defined complexes. Finally, investigations into the distance dependence of the energy transfer between aromatic chromophores and lanthanide ions have been undertaken. The synthesis of a model system linking a phenanthridine donor to a europium complex by poly(valine) spacer units is described. Preliminary photophysical results show that the quantum yield of emission by europium decreases as the distance between the donor acceptor pair is increased.
27
Cavaco, Carolina Cavaco M. Carolina. "Structural and dynamic properties of giant polymer-like lecithin reverse micelles /." [S.l.] : [s.n.], 1994. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10897.
Full text
28
Mat, Hanapi bin. "Protein extraction using reverse micelles : system parameters and mass transfer studies." Thesis, Imperial College London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434439.
Full text
29
Jarudilokkul, Somnuk. "Protein extraction using reverse micelles : selectivity, activity recovery and contactor design." Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/11777.
Full text
30
Doolittle, John William Jr. "Synthesis of microporous faujasitic zincophosphates in novel environments." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1116983708.
Full text
31
Hicks, Tanya Temaca. "Preparation, characterization, and activity of mono-dispersed supported catalylsts [sic]." Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-07212004-102914/unrestricted/hicks%5Ftanya%5Ft%5F200412%5Fms.pdf.
Full textAbstract:
Thesis (M.S.)--Chemical Engineering, Georgia Institute of Technology, 2005.Agrawal, Pradeep K., Committee Chair ; Bommarius, Andreas S., Committee Member ; Schork, F. Joseph, Committee Member. Includes bibliographical references.
32
Borracini, Heloisa Maria Pitaro. "Estudo do processo de extração da bromelina por micelas reversas em sistema de descontinuo." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267644.
Full textAbstract:
Orientador: Elias Basile TamborgiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
Made available in DSpace on 2018-08-06T23:13:38Z (GMT). No. of bitstreams: 1 Borracini_HeloisaMariaPitaro_M.pdf: 561004 bytes, checksum: e3b9d20443cd5c9315ba77c397ee51dc (MD5) Previous issue date: 2006
Resumo: Bromelina é o nome dado a um conjunto de enzimas proteolíticas encontradas nos vegetais da família Bromeliaceae, da qual o abacaxi é o mais conhecido. A bromelina tem diversos usos, todos baseados em sua atividade proteolítica. Com a necessidade de desenvolver novos processos de purificação e concentração desses compostos, a extração líquido-líquido por rnicela reversa mostra-se como uma técnica atrativa, pois a micela reversa possui a capacidade de solubilizar biomoléculas específicas de uma solução aquosa, como o extrato bruto do abacaxi. O objetivo desse trabalho foi estudar a recuperação da enzima bromelina através da técnica de extração líquido-líquido por rnicelas reversas. Para tanto, utilizaram-se três sistemas micelares distintos formados a partir de BDBAC (agente tensoativo catiônico), AOT (agente tensoativo aniônico) e CTAB (agente tensoativo catiônico). Foram realizados planejamentos estatísticos com o intuito de realizar uma triagem das variáveis significativas em cada processo. A metodologia de superfície de resposta foi empregada para quantificação dos níveis das variáveis significativas à extração. No presente trabalho são apresentados estudos da influência conjunta que alguns parâmetros exercem sobre a extração líquido-líquido da bromelina com rnicelas reversas, nas etapas de extração e re-extração, para fins de caracterização, modelagem e otirnização
Abstract: Bromelain is a set of proteolitics enzymes found in vegetables of the Bromeliaceae family, from which pineapple is known more. Bromelain has several uses, alI based on its proteolitics activity. There are the necessity to develop new processes for purification and concentration of these composites, the liquid-liquid extraction by reversed micelles reveals as one attractive technique, therefore it has had the specific capacity of getting solub1e biomolecules of an aqueous solution, as the crude extract of the pineapple. This is a study on the recovery of bromelain through liquid-liquid extraction by reversed micelles. Three distinct micelar systems formed from BDBAC (cationic surfactant), AOT (anionic surfactant) and CTAB (cationic surfactant) were employed. Statistical designs were used to select the most significant variables for each process. Surface response methodology was used to quantify the levels of the significant variables. In this work systematic studies are performed on the influence that certain parameters have on the recovery of bromelain through liquid-liquid extraction by reversed micelles, concerning forward and back extration. The goal is the system mathematical characterization and otimization
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
33
Vitart, Xavier. "Contribution a l'extraction liquide-liquide et a la separation de certains elements du groupe viii, notamment du ruthenium, par des systemes synergiques polyimines aromatiques-echangeurs cationiques micellaires." Paris 6, 1987. http://www.theses.fr/1987PA066663.
Full textAbstract:
Caracterisation et quantification des equilibres chimiques qui regissent un nouveau systeme d'extraction dont l'apport est de pouvoir operer a partir du milieux fortement acides avec des cinetiques d'extraction tres rapides. Des substitutions de coordinats sont prealablement operees en phase aqueuse. L'extraction elle-meme est realisee par des echangeurs cationiques formant des micelles inverses dans les diluants utilises. Cas de l'acide dinonylnaphtalenesulfonique
34
Regalado, Gonzalez Carlos. "Protein extraction using reverse micelles recovery optimization, purification and mass transfer studies." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262612.
Full text
35
Göklen, Kent Emir. "Liquid-liquid extraction of biopolymers : selective solubilization of proteins in reverse micelles." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/15103.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Bibliography: leaves 297-308.
by Kent Emir Göklen.
Ph.D.
36
Michaels, Melissa A. "Quantitative Model for the Prediction of Hydrodynamic Size of Nonionic Reverse Micelles." VCU Scholars Compass, 2006. http://scholarscompass.vcu.edu/etd/789.
Full textAbstract:
The sizes of nonionic reverse micelles were investigated as a function of the molecular structure of the surfactant, the type of oil, the total concentration of surfactant [NP], the ratio of NP4 to total surfactant (r), the water to surfactant molar ratio (ω), temperature, salt concentration, and polar phase. The basis of our investigation was nonylphenol polyethoxylates - NP4 and NP7. Micelle sizes were determined using dynamic light scattering (DLS). A central composite experimental design was used to quantitatively model reverse micelle size as a function of ω, [NP], and r. The model has demonstrated the capability of predicting the mean diameter of micelles from 4 to 13 nm with a precision of ± 2 nm as measured by DLS. This quantitative correlation between the size of reverse micelles and the synthetic variables provides the foundation for choosing experimental conditions to control reverse micelle size.
37
Cheng, Xu. "Synthesis of Nanometer-sized Yttrium Oxide Particles in Diisooctyl Sodium Sulphosuccinate/Isooctane Reverse Micelle Solution." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/31610.
Full textAbstract:
This thesis describes the synthesis of yttrium oxide nanoparticles in an AOT/isooctane reverse micelle solution. Two synthetic methods are compared. First is the precipitation reaction between yttrium nitrate and ammonia, second is the hydrolysis of yttrium isopropoxide. The effects of annealing of the resulting the yttrium oxide nanoparticles are also described.
The nitrate method produced network-like aggregates of yttrium oxide nanoparticles ranging from 10 nm to 40 nm in diameter. Reaction conditions, including the water/AOT ratio (1 to 15), the nitrate concentration (0.02 M to 1.0 M), the ammonia concentration (2 M to 14.8 M), the AOT concentration (0.1 M and 0.5 M), the aging time (1 h to 5 d), and the washing method, were varied to investigate their influence on nanoparticle formation. The optimized synthetic conditions were: a water/AOT ratio of 7.5, [NO3-] = 0.5 M, [NH3] = 2 M, and [AOT] = 0.1 M.
The as-prepared yttrium oxide nanoparticles had highly distorted structures related to the cubic Y2O3 phase. Annealing improved the crystallinity of the as-prepared nanoparticle products and led to larger particles. As annealing temperatures increased, the yttrium oxide nanoparticles gradually evolved into the cubic Y2O3 phase. However, an unknown intermediate phase was also observed during the annealing process, which disappeared when the annealing temperature was sufficiently high and the annealing time was long enough (>1000 °C and 4 h).
As-prepared products from the isopropoxide hydrolysis also contained network-like nanoparticle aggregates. Particle sizes ranged from 10 nm to 20 nm. Some experimental conditions were varied; they were the water/AOT ratio (10 to 40), the isopropoxide concentration (0.0001 M to 0.003 M), the aqueous phase pH (7.0 and 12.0), the aging temperature (room temperature, approximately 25 °C, and refluxing temperature, approximately, 100 °C), and the aging time (1 h to 5 d). Transmission Electronic Micrographs showed that products of desirable morphology could be produced in a much wider range of experimental conditions by this method compared to those produced by nitrate hydrolysis.Master of Science
38
Fischer, Gilvan Anderson. "Estudo e modelagem do processo de extração da bromelina por micelas reversas em uma coluna de campanulas pulsantes." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267426.
Full textAbstract:
Orientador: Elias Basile TambourgiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
Made available in DSpace on 2018-08-06T05:30:03Z (GMT). No. of bitstreams: 1 Fischer_GilvanAnderson_D.pdf: 1330009 bytes, checksum: a03c001d3375eaae07873f0e8dd8d168 (MD5) Previous issue date: 2006
Resumo: Bromelina é um conjunto de enzimas proteolíticas encontradas nos vegetais da família Bromeliaceae, da qual o abacaxi é o mais conhecido. A bromelina tem diversos usos, todos baseados em sua atividade proteolítica. Com a necessidade de desenvolver novos processos de purificação e concentração desses compostos a extração líquido-líquido por micela reversa mostra-se como uma técnica atrativa, pois possui a capacidade de solubilizar biomoléculas específicas de uma solução aquosa, como o extrato bruto do abacaxi. Dentre os equipamentos disponíveis para a extração líquido-líquido foi usada uma micro-coluna de campânulas pulsantes, visando a separação e purificação de biomoléculas em operação contínua. A melhor condição de extração da bromelina com micelas reversas em operação batelada foi aplicada na coluna de extração. Com o objetivo de encontrar as condições ótimas de operação da coluna foi utilizada a técnica de planejamento de experimentos do tipo estrela, de forma a abranger toda região de operação. Para isto variouse a razão Vazão Fase Leve/Vazão Total e o intervalo entre os pulsos na entrada para determinar as variações na saída do rendimento de proteína total e o fator de purificação. Os valores dos pontos ótimos para as variáveis respostas encontrados foram: fator de purificação de 5 vezes e produtividade de 1,28 mg/min. E as condições operacionais que levam ao ótimo das respostas foram: Vazão Fase Leve/Vazão Total de 0,67 e intervalo entre os pulsos de 1 s. Para representar a dinâmica de operação da coluna de extração usouse uma simples aproximação baseada nas redes neurais, pois este modelo de conexão tem a habilidade de aprender procedimentos complexos do sistema físico. As entradas foram representadas pelos passados e presentes valores da razão vazão fase leve/vazão total e no intervalo entre os pulsos, e as saídas o valor presente do rendimento de proteína total e o fator de purificação. Com o objetivo de encontrar a melhor topologia, treinou-se a rede com o algoritmo Regularização Bayesiana, variando-se o número de neurônios da camada intermediária para encontrar o melhor modelo. A topologia final da rede neural foi 16-9-2, com funções de ativação sigmoidal. Observou-se o bom desempenho da rede neural com respeito à Proteína Total e o Fator de Purificação em toda a faixa de valores desejada
Abstract: Bromelain is a set of proteolitics enzymes found in vegetables of the Bromeliaceae family, from which pineapple is known more. Bromelain has several uses, ali based on its proteolitics activity. There is the necessity to develop new processes for purification and concentration of these composites, the liquid-liquid extraction for reversed micelles reveals as one attractive technique, therefore it has had the specific capacity of getting soluble biomolecules of an aqueous solution, as the crude extract of the pineapple. Amongst equipment for the liquid-liquid extraction available it was developed a microcolumn of pulsed caps, with the purpose to get an equipment for the accomplishment of extraction processes liquid-liquid, appropriate for the separation and purification of biomolecules in continuous operation. The best condition of bromelain extraction with reversed micelles in batch operation was applied in the extraction column. To find the best operation conditions of the column, the star design of experiments was used, covering ali region of operation. For this it had been varied the ratio between low density phase to total flow and the range of time between pulses on the input to determine the variations of the total protein yield and purification factor on output each three minutes. The best values found were: 5 for purification factor and 1.28 mg/min for productivity. And operational conditions that lead to results were: 0.67 for the ratio between low-density phase to total flow and 1 s for range of time between pulses. To represent the dynamics of operation of the extraction column a simple approach based on the neural networks was used, therefore this model of connection has the ability to leam complex procedures of the physical system. The input had been represented by the pasts and presents values of the ratio between low density phase to total flow and the range of time between pulses, and the outputs the present value of the total protein yield and purification factor. To find the best topology, the network was trained with Bayesian Regularization algorithm, varying the number of neurons on hidden layer to find the best model. The final topology of the neural network was 16-9-2, with sigmoid activation functions. It was observed that the performance of the neural network is good with respect to the total protein yield and purification factor in ali range of values desired.
Doutorado
Sistemas de Processos Quimicos e Informatica
Doutor em Engenharia Química
39
Souto, Ana Lúcia Carneiro Fernandes. "Micelas reversas e a interação de peptídeos melanotrópicos." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-14062012-142956/.
Full textAbstract:
Sabe-se que em sistemas biológicos, as funções de proteínas e de hormônios estão relacionadas com suas conformações espaciais e que suas estruturas e funções são freqüentemente influenciadas pela interação com os lipídeos das membranas plasmáticas e/ou intracelulares. Devido à importância das interações entre as proteínas e hormônios com as membranas, vários estudos têm sido realizados empregando modelos que simulam as membranas, pois as biológicas são estruturas bastante complexas. Entre esses modelos esta o de micelas reversas que pode ser considerado atualmente como o que melhor reproduz as condições existentes in vivo, pois a água presente nesse sistema e uma ótima representação para a água presente em sistemas biológicos em torno dos receptores de membrana. Visando estudar a interação do hormônio melanócito estimulante (- MSH) e do peptídeo sintético melanotrópico análogo (MSH1) com um modelo de membrana, na tentativa de compreensão de seu papel biológico, usamos micelas reversas preparadas com o anfifílico bis-(2-etilhexil)sulfosucinato de sódio, abreviado AOT. É sabido que - MSH é importante na regulação da pigmentação da pele, alem de estar relacionado a vários processos fisiológicos e neurológicos. Mais recentemente, foram encontradas evidencias de que ele atua também como neurotransmissor ou neuromodulador na aprendizagem, memória e capacidade de concentração. Clinicamente, os peptídeos melanotrópicos podem eventualmente ser utilizados no tratamento de alterações pigmentares e na detecção e erradicação de melanomas. Realizamos medidas de ressonância paramagnética eletrônica e de fluorescência de estado estacionário e resolvida no tempo para estudar a dinâmica interna dos peptídeos melanotrópicos na interação com micelas reversas de AOT. Monitoramos a fluorescência do resíduo Triptofano localizado na nona posição da seqüência de aminoácidos dos peptídeos melanotrópicos. A supressão da fluorescência do resíduo triptofano por acrilamida (que fica no meio micelar) também foi medida para auxiliar na tentativa de localizar a posição do fluoróforo nas micelas reversas. Dos espectros de EPR obtidos com o marcador de spin 5-SASL observamos que, com o aumento do tamanho das micelas reversas pelo aumento da quantidade de água, a região das cabeças polares tende a ficar flexível enquanto que, em oposição, aumenta a rigidez, a polaridade ordem da região das cadeias. Os resultados obtidos para o acréscimo de solução tampão fosfato e para soluções contendo Trp, LTL, -MSH e MSH1 são similares mostrando que essa técnica fornece informações sobre as micelas, independente da interação das mesmas com os peptídeos. Dos resultados obtidos com a fluorescência para o grau de anisotropia, tempo de vida e comprimento de onda de máxima emissão observamos que os fluoróforos utilizados (Trp, LTL, -MSHe MSH1) experimentam uma região menos polar e mais rígida do que a água. Vimos também que com o aumento da quantidade de água nas micelas reversas os peptídeos e o aminoácido tendem a assumir determinadas localizações na interface, sendo que o Triptofano fica no meio mais hidratado que não é a agua bulk. Os espectros de decaimentos associados mostram a ocorrência de conformações com diferentes graus de exposição do Triptofano ao ambiente aquoso. Assim, pudemos perceber que o Trp é o mais exposto à água tendendo a localizar-se na região de água estruturada. O LTL fica ancorado na região da interface e os peptídeos melanotrópicos inserem-se na região das cadeias hidrocarbônicas, sendo que o -MSH insere-se mais profundamente. Observamos também dos espectros de decaimentos associados diferenças das distribuições conformacionais para os hormônios melanotrópicos, especialmente para as micelas reversas maiores que simulam a situação biológica, o que pode estar relacionado com as diferentes atividades bio1ógicas dos mesmos.The biological function of proteins and hormones is related to their conformations and both structure and function are frequently dependent on the interactions with lipids of plasmatic and intracelular membranes. Due to the complexity of biological membranes, many studies about these interactions employ model membranes. The reverse micelle is a good model, for it offers an adequate representation of the structured water that is present in biological systems around the membrane receptors. We report here studies of the interaction of -melanocyte stimulating hormone (-MSH) and one synthetic analogue (MSH1) with reverse micelles prepared from the amphyphylic sodium bis-(2-ethylhexyl)sulfosuccinate (AOT) in isooctane. The -MSH is important in the regulation of skin pigmentation and is also involved with other physiological process. It was recently found evidences of its action as a neurotransmitter or neuromodulator in learning, memory and attention. It is claimed that potent analogues of melanotropin hormones could be used in the therapy of pigmentary disorders and detection and treatment of melanome. Electron paramagnetic resonance (EPR), steady state fluorescence and time-resolved fluorescence were employed to study the internal dynamics of the melanotropins in interaction with reverse micelles of AOT. We monitored the fluorescence of the residue tryptophan located in the 9 position of the aminoacids sequence of -MSH and MSH-l. The tripeptide Lysil-tryptophyl-Lysine (LTL) and the isolated aminoacid tryptophan were also investigated as simpler molecules interacting with the reverse micelles. It was also measured the fluorescence quenching by acrylamide, to obtain more information about the peptide location in reverse micelles. We monitored the EPR spectra of the spin label 5-doxyl stearate acid (5-SASL) at increasing values of Wo hat is the ratio between the number of water molecules and the number of AOT molecules. The region of the polar head gains flexibility when the size of the reverse micelles increases (due to increase in water content) and, opposite to this, the region of the hydrophobic tail becomes more rigid, showing higher order and polarity. Similar effects were observed upon addition of solutions containing either tryptophan, or LTL, or -MSH and MSH-1, indicating that the EPR measurements gave information about the changes in the micelles promoted by water molecules, independent of the interactions with the peptides. Monitoration of fluorescence parameters like spectral position of emission band, anisotropy and lifetime demonstrated that the environment around the fluorophore, in all compounds, is less polar and more rigid than bulk water. Those parameters reflect the location of the compounds in the heterogeneous isooctane/AOT/water medium and are sensitive to the changes induced in the micelles by the increasing the amount of water. However, in large micelles having wo above 10, the modifications detected by fluorescence re small and the addition of water no more affects the location of the fluorophores. Quenching measurements gave additional support to the data indicating that the different compounds occupy different positions in the large reverse micelles, but in any case they are in the interface region, without dispersing into the bulk water. Decay associated spectra allowed the identification of conformations with various degree of exposition to polar and non polar media. The conformation related to the long lifetime is more exposed to water while that associated to the intermediate lifetime is preferentially stabilised in non polar media. The native hormone -MSH in the large micelles shows predominance of the conformation sensing a non polar environment, with similar results presented by the analogue MSH-1. Those melanotropins are in the region of the hydrocarbon chain, with slightly deep location for the native hormone. The tripeptide LTL is anchored in the interface region, probably stabilised by electrostatic interaction between the charged groups in the peptide and the negative charge in AOT. Finally, the tryptophan is most exposed to water, probably interacting with structural water near to the interface.
40
Liu, Yan 1975. "Laccase-catalyzed oxidation of bisphenol A in a non-aqueous liquid reverse micelles." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82614.
Full textAbstract:
The catalytic oxidation of bisphenol A (BPA) by laccase (EC 1.10.3.2) has recently attracted considerable attention because laccase can rapidly transform potentially persistent and toxic pollutants such as bisphenol A in the presence of molecular oxygen. Direct treatment of wastewaters containing bisphenol A would require excessive amounts of laccase if the enzyme is lost with the effluent and, thus, treatment would be cost-prohibitive. Therefore, strategies are desired for retaining the enzyme in the treatment system. It was envisioned that this could be accomplished by extracting pollutants into a non-aqueous phase liquid and then treating them in that phase using enzymatic catalysis. In such a treatment scheme, preserving the enzyme and maintaining its high reactivity in a non-aqueous phase liquid can be easily achieved through the use of reverse micelles.Therefore, this study was conducted in order to examine the efficiency of enzymatic treatment of BPA in reverse micelles. It was found that laccase entrapped in the reverse micelles formed by dioctyl sulfosuccinate sodium salt (AOT) and isooctane exhibited the highest catalytic activity at a pH of 6, a water content of 10 (i.e., the molar ratio of water to AOT), and an AOT concentration of 80 mM.
41
Rabie, Hamid Reza. "Reverse micellar extraction of ionic and zwitterionic species from aqueous solutions." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34432.
Full textAbstract:
Experimental data have been measured at 23$ sp circ$C for reverse micelles formed by Aerosol-OT (AOT), and by dioctyldimethyl ammonium chloride (DODMAC), or bromide (DODMAB) in an organic phase in contact with an aqueous salt solution. The following studies in Winsor type II systems have been considered: (i) ion distribution in AOT and DODMAC reverse micellar systems, (ii) extraction of zwitterionic amino acids with AOT reverse micelles, (iii) extraction of proteins with DODMAC reverse micelles, (iv) water uptake of AOT, DODMAC and DODMAB reverse micelles. Depending on the study, the effects of the following variables were investigated: salt, amino acid or protein type and concentration, pH, volume ratio of the phases in contact, nature of solvent, alcohol concentration, surfactant type and concentration, and the presence of the impurities in the case of mixed salts.A systematic approach to describe the solubilization of different solutes in the reverse micellar phase, referred to as the "active interface model," has been adopted. Based on the active interface model, the reverse micellar interface is chemically active. Therefore, different species are able to react with the surfactant head groups at the reverse micellar interface and form different complexes.
Based on the active interface model, a theory has been developed for the ion distribution in reverse micellar systems. This theory has excellent capability for prediction of ion distribution in multiple salt systems. Dimensionless groups have been defined to regroup several independent variables. The theory of ion distribution has been further extended to predict the extraction of zwitterionic amino acids and proteins.
A general model, which accurately predicts the water content in the organic phase, has been developed for reverse micelles formed by the contact method. This model describes well the appearance of a maximum in water uptake, observed for the first time in this work, with an increase in salt concentration.
42
Rabie, Hamid Reza. "Reverse micellar extraction of ionic and zwitterionic species from aqueous solutions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30364.pdf.
Full text
43
fadhil, ali abd al-karim alkarim. "Reversed-phase and surfactant modified reversed-phase high and ultra-high performance liquid chromatography of phenolic and aliphatic carboxylic acids." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1574428923192499.
Full text
44
Wang, Chengle. "Controlled synthesis and properties of layered double hydroxides." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:80fc02cc-3e79-438f-9985-ae1663fc5554.
Full textAbstract:
The aims of this thesis are concerned with the synthesis of layered double hydroxide nanoparticles with controlled morphology and particle size distribution and an investigation of their physical properties. An introduction of layer double hydroxide chemistry, especially existing synthetic approaches, is reviewed in Chapter 1. Structural investigations, characterisation techniques, the properties and the applications of LDHs are discussed consecutively. The first successful synthesis of lithium aluminium nanorods using the hydrothermal treatment of a gibbsite precursor with a rod-like morphology is described in Chapter 2. The rod morphology is depicted using electron microscopy and confirmed by comparing refined X-ray diffraction patterns to a standard sample. Chapter 3 describes the application of reverse microemulsion method to prepare Co-Al and Ni-Al LDH nanoplatelets. The LDH particle sizes can be effectively controlled, and the structures of the nanoplatelets are investigated. The magnetic properties of the LDH nanoplatelets are dependent on the size of the nanoplatelets. A novel single component microemulsion system for the synthesis of LDHs is developed in Chapter 4. Mg-Al LDH nanoplatelets were successfully synthesised with precise particle size control. The factors affecting the formation of the microemulsions and the mechanism of the synthesis are discussed. Chapter 5 focuses on the applications of the novel single component microemulsion methods to prepare a range of LDHs with different metal combinations including Co-Al, Ni-Al, Zn-Al, Li-Al, Ca-Al, and Ni-Fe. This method proves very effective at controlling the particle sizes. The magnetic properties of the LDHs containing paramagnetic transition metal centres have been studied in detail. In Chapter 6, the DIFFaX program has been used to simulate the XRD patterns of layered structures. The factors influencing the XRD patterns in these materials have been systematically investigated including the effects of particle size, stacking faults, and disorder. The XRD patterns of materials described in previous chapters are simulated using the latest DIFFaX+ code in order to estimate the particle sizes and stacking sequences. The characterising techniques and the experimental details are listed in Chapter 7.
45
Hicks, Tanya Temaca. "Preparation, Characterization, and Activity of Mono-Dispersed Supported Catalysts." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4765.
Full textAbstract:
Mono-dispersed supported Ni catalysts were synthesized using the water-CTAB-hexanol reverse micellar system. The core of the reverse micelles contained an aqueous solution of NiCl2. Dynamic light scattering measurements showed that microemulsions having a water-to-surfactant molar ratio, Wo, of 10 lead to reverse micelles with lowest polydispersity, longest stability, and size range of interest. At an oil-to-aqueous phase ratio of 2, the diameter of the reverse micelles was found to increase with Wo in a linear fashion. At higher values of Wo (i.e. 25-30), the polydispersity was found to increase when lowering the amount of surfactant in the system. Ultimately, O/A = 2 and Wo = 10 were chosen as optimal conditions for microemulsion preparation.
The aqueous NiCl2 concentration within the micelles was varied between 0.1 and 0.001 M. DLS results showed that although the average micelle diameter was between 70-83 nm throughout the range of metal salt concentrations, the crystallite size estimate based upon the reported micelle diameter and known aqueous NiCl2 concentration ranged between 2 to 7 nm. Therefore, the Ni crystallite size was varied by changing the aqueous NiCl2 concentration due to instability issues arising when changing the value of Wo.
After deposition onto an alumina mesh support, the particles were dried, calcined, and reduced to produce Ni clusters. SEM and EDS analysis was used to confirm the presence of Ni compounds after the calcination stage. By the varying the aqueous NiCl2 concentration within the micelles, .0039, .0013, and .00039 wt. % Ni catalysts were produced and characterized using SEM. Particles in the size range of 10-14 nm were noticed for the .0039 wt. % Ni catalysts after reduction, 7-11 nm for .0013 wt. % Ni, and 5-9 nm for .00039 wt. % Ni. The lower-end of these particle size ranges was comparable to the crystallite size estimates.
Ethane hydrogenolysis and ethylene hydrogenation reactions were conducted over the emulsion-prepared catalysts in order to determine particle size effects on catalytic activity. Results showed that the catalytic activity, defined in terms of per unit metal surface atom (or TON, turnover number), decreases with increasing particle size for the hydrogenolysis reaction. This trend may be due to an intrinsic size effect in which smaller particles exhibit the chemical or structural properties necessary for achieving a higher reaction rate. The results for ethylene hydrogenation showed that the reaction rate did not significantly change with crystallite size, confirming that the reaction is facile or structure-insensitive.
46
Ueda, Ana Cláudia. "Aplicação de micelas reversas na remoção de corantes têxteis catiônicos." Florianópolis, SC, 2006. http://repositorio.ufsc.br/xmlui/handle/123456789/89344.
Full textAbstract:
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia QuímicaMade available in DSpace on 2012-10-22T19:40:31Z (GMT). No. of bitstreams: 1 225998.pdf: 1923818 bytes, checksum: 7b977346b3b9f79be8e47a40560e560f (MD5)
A remoção de corantes de águas residuárias têxteis tem sido um assunto de grande interesse nas últimas décadas. Hoje em dia, este tema tem tido destaque principalmente devido às novas normas ambientais à cobrança pela utilização da água. Os corantes têxteis modernos possuem alto grau de estabilidade química e fotocatalítica, de forma a manter sua cor por mais tempo. Devido à característica recalcitrante dos corantes, uma combinação de tratamentos é necessária para a purificação do efluente. Os mais estudados são tratamentos por: membranas, adsorção, oxidação avançada e físico-químicos, como coagulação/floculação e microemulsões. Os surfactantes são moléculas compostas por uma parte hidrofílica, denominada cabeça e uma cadeia linear carbônica apolar (hidrofóbica), denominada cauda. As micelas são agregados de monômeros de surfactantes, são estáveis termodinamicamente, isotrópicas e de baixa viscosidade. No caso das micelas reversas, sua formação se dá em solventes orgânicos contendo ínfimas quantidades de água, na qual a cabeça (polar) fica voltada para o pequeno "poço aquoso" em seu interior e a cauda (apolar) fica voltada para fora, na fase orgânica, "protegendo" a parte hidrofílica. No presente trabalho foi investigada a aplicação de micelas reversas na remoção de corantes têxteis catiônicos, através da variação das concentrações de corante e de surfactante, da temperatura, do efeito de sal e do volume de fase orgânica no sistema. Este método permite, além da remoção do corante, o seu posterior reaproveitamento através da recuperação da fase orgânica, bem como a reutilização da própria fase orgânica. Foi estudada a remoção dos corantes catiônicos (CI Basic Blue 41, CI Basic Red 46 e CI Basic Yellow 28) com o surfactante aniônico (Dodecil sulfato de sódio ou Lauril Sulfato de Sódio - SDS). Como solvente orgânico foi utilizado o Álcool Isoamílico e o sal foi o Cloreto de Potássio. A concentração de corante presente na fase aquosa foi determinada através de análise espectrofotométrica e os resultados foram expressos pela porcentagem de remoção do corante da fase aquosa. Os resultados obtidos experimentalmente foram analisados estatisticamente através do Método da Superfície de Resposta. Os ensaios experimentais forneceram resultados de remoção máxima superiores a 99% para os três corantes. A análise estatística dos resultados experimentais forneceu como principais fatores significativos a porcentagem de fase orgânica presente no sistema e a concentração de surfactante. Esta análise também forneceu um modelo estatístico-matemático que representa o processo, cujos coeficientes de determinação foram de 85, 70 e 87% para os corantes CI Basic Yellow 28, CI Basic Blue 41 e CI Basic Red 46, respectivamente.
47
Yang, Chin-Lin, and 楊青林. "spin crossover compound in nano-confined reversed micelle system." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/36002741994487726365.
Full textAbstract:
碩士國立臺灣大學
化學研究所
92
We are interesting in two step system,because it can be used in memory material.In this work,we try to prepare a material have transition temperature in RT.We can change the transition temperatue by control the micelle size.
48
Weng, Ji-Yu, and 翁基育. "Extraction and concentration of cytochrome c using reversed-micelle in countercurrent chromatograph." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/43861885157908817721.
Full textAbstract:
碩士國立交通大學
應用化學系所
92
Recently we have applied a countercurrent chromatograph to extract and concentrate cytochrome c molecules in our laboratory. The forward extraction was accomplished using an AOT-containing hexane solution retented in the countercurrent chromatograph by eluting a 0.2 M KCl cytochrome c aqueous solution and the backward extraction was performed by injecting a 5 mL alkaline solution through a sample loop to elute and liberate the protein molecules seized by the reverse micellar solution. The protein molecules were thus transferred from a low pH to a high pH aqueous solution via a micellar solution. Due to slow backward extraction rate and low recovery, a high pH, such as 12.8, solution was required. However, this alkaline solution would spoil the reverse micellar system permanently; therefore it could not be reused. The second drawback was the possibility of denature of the protein molecules. In this study, we discovered that the addition of ethyl acetate to the micellar solution may help improve the backward extraction as well as the sample recovery rate. In addition, we applied a buffer solution to replace the un-buffered solution used previously during the backward extraction. The outcome showed that a buffered solution with a lower pH (such as 11) could recover higher yield than an un-buffered solution of a higher pH. Accordingly, the micellar solutions could remain intact longer than those treated un-buffered solutions with higher pH values during the backward process. Finally, we achieved to concentrate a 10.8 mg in 540 mL cytochrome c aqueous solution to a 10.1 mg in 60 mL aqueous solution. The recovery was 93.2% with a volume reduction of one ninth to the original volume.
49
賴雋仁. "Combining countercurrent chromatography and reversed-micelle technologies to extract and concentrate protein molecules." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/88384559777812821015.
Full text
50
張文燈. "Optimization of reversed micelle liquid-liquid extraction for enzymepurification by experimental design methods." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/24829483690031641072.
Full text