Global ETD Search

1	Dispersion, assembly and electrochemistry of graphene at the liquid-liquid interface Rodgers, Andrew Norman John January 2015 (has links) The dispersion of graphene in 1,2-dichloroethane (DCE), its subsequent attachment at the water-DCE interface and the reduction of oxygen at the water-DCE interface proceeding via interfacial graphene have been investigated. Using addition of an electrolyte which screens surface charge, it was found that electrostatic repulsions play a significant role in determining the kinetic stability of lyophobic non-aqueous graphene dispersions. The onset of aggregation was determined and it was found that dispersions prepared from higher-oxygen content graphite were more stable than those prepared from lower-oxygen content graphite, indicating that oxygen content is important in determining the surface charge on graphene in non-aqueous dispersion. The presence of organic electrolyte was also found to promote assembly of graphene into a coherent film at the liquid-liquid interface. Measurement of the liquid-liquid interfacial tension and three-phase contact angle revealed that the energetics of particle attachment did not change in the presence of organic electrolyte, thus indicating a mechanism of inter-particle electrostatic repulsion minimisation through surface charge screening. Interfacial graphene was found to display a catalytic effect toward the oxygen reduction reaction at the water-DCE interface. A bipolar cell was developed which showed that this reaction occurs heterogeneously, with graphene acting as a conduit for electrons across the water-DCE interface. 541
2	Study of Lithium Solvation Environments in Water-saturated Nitrobenzene Moakes, Greg 14 November 2006 (has links) It was found that there exist three major water environments when water is dissolved in nitrobenzene. 2H NMR has proved that these solvatomers exist irrespective of whether lithium salt is added to the system. 7Li NMR experiments suggested that the first solvatomer is majority nitrobenzene, the second a mixed solvation shell consisting of nitrobenzene and water and the third solvatomer is a large water aggregated at the glass surface. The mixed solvation state is short lived and is promoted by addition of water of by supersaturating the system upon cooling. This is a high energy state and decays either into the homogenous bulk NB state or to the surface of the glass wall, depending on if glass surface is present. In the 7Li NMR experiments, the hydrophobicity of the salt, determined by the anion, affects the relative intensity of the three 7Li resonances. Addition of lithium serves to promote hydrogen bonding in the majority nitrobenzene solvatomer, as confirmed by FTIR and neutron diffraction studies. There is no evidence that it has an effect on the size of the mixed solvatomer or the water aggregate immobilized on the glass surface. A reasonable hypothesis is that lithium exchanges between the water species which are formed independent of lithium involvement. The system is summarized as follows: Below critical water concentration (~200mM) nitrobenzene/water is a homogeneous distribution of water molecules in nitrobenzene. Addition of lithium salt to such a system has two main affects. First, the lithium promotes hydrogen bonding between the dissolved water molecules, as confirmed by FTIR and neutron scattering. Second, the hydrogen bonded water may precipitate causing microheterogeneity of the system, leading to a second resonance observed in both the 2H and 7Li NMR spectra (LiNB/W). In the presence of glass, a third solvation state can nucleate at the glass surface; this solvation state has character even closer to that of bulk water (LiW). These two supplementary solvation states can be artificially induced by either adding aliquots of water or cooling. Electrochemistry Liquid-liquid interface Solvation FTIR NMR ITIES Solution (Chemistry) Surface chemistry Lithium silicates Nitrobenzene Solvation Electrochemistry Interfaces (Physical sciences)
3	Upon your sons and daughters : an analysis of the Pentecostalism within the Jesus People Movement and its aftermath Bustraan, Richard Anderson January 2011 (has links) The Jesus People Movement was a large religious phenomenon that arose out of an amalgamation of the American counterculture and Hippie movements and American Pentecostalism. Beginning in 1967 the movement‘s early participants were mostly hippies who had claimed a conversion experience and instantaneous healing from drug addiction through an encounter with Jesus Christ. By the mid-1970s the growing phenomenon had attracted a broad range of youth, many of whom were not former hippies, but who did relate to the counterculture movement and the generation gap. Several enduring institutions arose from the heyday and have continued to impact American Pentecostalism and American Christianity more broadly. This thesis examines the historical links between the Jesus People Movement, American Pentecostalism, and the Hippie movement as well as the sociological and theological resemblance to American Pentecostalism. Based on the family resemblance analogy, the thesis concludes that the Jesus People Movement should be included as a significant part of the story of American Pentecostalism. 200
4	Časově rozlišená potenciometrie na kapalném mezifází / Time-resolved potentiometry on liquid-liquid interface Mansfeldová, Věra January 2016 (has links) Věra Mansfeldová: Time-resolved potentiometry on liquid-liquid interface (Dissertation thesis) Abstract The aim of this work is to explore the method of temporal resolution in potentiometry as a new prospective electrochemical analytical technique. In connection with interface of two immiscible electrolyte solutions (ITIES) it may find utilization in analytical chemistry. This technique up to my knowledge has not been published yet. Potential response of analyte on liquid/liquid interface includes both distribution processes, their temporal resolution and redox processes, which specificity can modified by changing the composition of individual phases. Unlike "classic" potentiometric techniques, limited just to potential determination, this method, which I have given the working name "time resolved potentiometry at liquid-liquid interface" utilizes time development of potential response, which was found to be an analyte-specific function. The time resolved potentiometry presented in this work includes time course of potential response to analytical parameters specific for particular analyte. It brings series of data characterizing the analyte in given environment in a similar manner as spectra and may allow creating analyte-specific data package - fingerprint. Combination with ITIES allows, unlike...
5	Modification électrochimique de l'interface liquide - liquide avec de la silice mésoporeuse / Electrochemical modification of the liquid - liquid interface with mesoporous silica Poltorak, Lukasz 25 September 2015 (has links) Ce travail combine l'électrochimie à l'interface liquide - liquide avec le procédé sol - gel pour la modification interfaciale avec de la silice mésoporeuse. Dans la première partie de ce travail, l’interface liquide – liquide macroscopique a été utilisée pour séparer la solution aqueuse de l'espèce de précurseur de silice hydrolysées (tétraéthoxysilane (TEOS)) de l'agent tensioactif cationique (cethyltrimethylammonium (CTA+) qui a agi comme un template et a été dissous dans le dichloroéthane. Le dépôt de matériau de silice a été déclenchée par le transfert du CTA+ à partir de la phase organique vers la phase aqueuse. CTA+ qui a transféré à la phase aqueuse a catalysé la réaction de condensation de la silice sur l’interface liquide – liquide. Le dépôt de silice à des interfaces liquide – liquide miniaturisées était la deuxième partie de ce travail. Les dépôts stables sur le côté de l'interface ont été synthétisés in situ par voie électrochimique. La stabilité mécanique des dépôts de silice permis un traitement thermique de la silice. Basé sur les techniques d’imagerie (par exemple SEM) il a été constaté que les dépôts forment des hémisphères pour des temps plus long. La réaction interfaciale a également été suivie in situ par spectroscopie Raman confocale. Caractéristiques moléculaires de l'interface ont été modifiées de manière spectaculaire une fois les espèces CTA+ ont été transférés à la phase aqueuse. Les interfaces liquide – liquide miniaturisés et modifiés ont également été évaluée avec le transfert voltampérométrique / This work combines the electrochemistry at the interface between two immiscible electrolyte solutions (ITIES) with the Sol – Gel process of silica leading to an interfacial modification with mesoporous silica using soft template. In the first part of this work the macroscopic liquid – liquid interface was employed to separate the aqueous solution of the hydrolyzed silica precursor species (tetraethoxysilane (TEOS)) from the cationic surfactant (cethyltrimethylammonium (CTA+)) dissolved in the dichloroethane. The silica material deposition was controlled by the electrochemical CTA+ transfer from the organic to the aqueous phase. Template transferred to the aqueous phase catalyzed the condensation reaction and self-assembly resulting in silica deposition at the interface. Silica deposition at the miniaturized ITIES (membranes supporting array of micrometer in diameter pores were used in this regard) was the second part of this work. Silica interfacial synthesis performed in situ resulted in stable deposits growing on the aqueous side of the interface. Mechanical stability of the supported silica deposits allowed further processing – silica material was cured. Based on imaginary techniques (e.g. SEM) it was found that deposits forms hemispheres for longer experimental time scales. Interfacial reaction was also followed with in situ confocal Raman spectroscopy. Molecular characteristics of the interface were changed dramatically once CTA+ species were transferred to the aqueous phase. Array of microITIES modified with silica was also assessed by ion transfer voltammetry Tetraethoxysilane Interface liquide – liquide Ities Silice mésoporeuse Procédé Sol – Gel Cetyltrimethylammonium Tetraethylammonium Tetramethylammonium Tetrabuthylammonium Voltammétrie cyclique Spectroscopie Raman confocale Tamis moléculaire Modification interfaciale Dépôt de silice Voltammétrie de transfert d’ions 4-Octylbenzenesulfonate Miniaturisation MicroITIES Μities Membrane à base de silicium mésoporeux Tetraethoxysilane Liquid – liquid interface Ities Mesoporous silica Sol – Gel process Soft template Cetyltrimethylammonium Worm like structures Tetraethylammonium Tetramethylammonium Tetrabuthylammonium PAMAM dendrimers Cyclic voltammetry Confocal Raman spectroscopy Molecular sieving Interfacial modification Silica deposition Ion transfer voltammetry 4-Octylbenzenesulfonate Miniaturization MicroITIES Μities Mesoporous silicon wafers 541.37 660.297

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