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Padoan, Sara <1991>. "DETERMINAZIONE DI COMPOSTI IONICI IN CAMPIONI ANTARTICI MEDIANTE CROMATOGRAFIA IONICA ACCOPPIATA ALLA SPETTROMETRIA DI MASSA." Master's Degree Thesis, Università Ca' Foscari Venezia, 2015. http://hdl.handle.net/10579/6891.
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Nel presente lavoro di Tesi è stato sviluppato un metodo analitico per la determinazione di anioni e cationi rispettivamente mediante cromatografia ionica accoppiata alla spettrometria di massa e cromatografia ionica con rivelazione conduttimetrica in campioni di aereosol atmosferico. Il metodo è stato validato valutando la linearità del segnale strumentale, limiti di rilevabilità e precisione strumentale, recuperi, accuratezza e ripetibilità della procedura analitica di preparazione dei campioni. Il metodo così ottenuto è stato applicato a campioni antartici raccolti in quattro campagne di campionamento condotte presso il sito costiero di "Mario Zucchelli Station" (estate 2010-11), il sito continentale di Concordia (estati 2011-12 e 2012-13) e presso nave Italica durante una campagna oceanografica (gennaio-febbraio 2012). I dati ottenuti sono stati quindi valutati al fine di studiare l'origine dell'aerosol marino e il comportamento durante il trasporto a lunga distanza.
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Straccialano, Raffaela. "Simulazioni atomiche di canali ionici del potassio: limiti del Force Field AMBER nelle stime di conduttanza." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/19971/.
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Le simulazioni atomiche dei canali ionici del K+ mettono in evidenza una significativa inaccuratezza: i valori di conduttanza del canale stimati sono molto distanti dai valori sperimentali. Per tentare di migliorare le simulazioni e i loro risultati, è necessario modificare il modello di Force Field impiegato. Si è scelto di adottare il modello di Force Field AMBER, uno dei più utilizzati per simulazioni di molecole biologiche in dinamica molecolare, e di agire sui valori dei parametri di Lennard-Jones cercando un set di valori che permetta di minimizzare la distanza tra la conduttanza stimata e la conduttanza sperimentale delle soluzioni saline. L’analisi ha dimostrato che non è possibile riprodurre in modo quantitativo i valori sperimentali di conduttanza di soluzioni saline di Na+ e K+ in simulazioni atomiche basate su un modello di Force Field additivo.
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BOZZA, SARA. "ARCHITETTURA IONICA A HIERAPOLIS DI FRIGIA." Doctoral thesis, Università Cattolica del Sacro Cuore, 2016. http://hdl.handle.net/10280/10487.
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La ricerca di dottorato si inserisce nel quadro delle attività della MAIER – Missione Archeologica Italiana a Hierapolis di Frigia (Pamukkale, Turchia) e nel filone degli studi di architettura antica relativi ai complessi edilizi dei centri microasiatici. Vengono analizzati, in particolare, alcuni edifici e materiali architettonici di ordine ionico emersi dalle recenti indagini di scavo, allo scopo di fornire una ricostruzione dei monumenti nella planimetria e negli alzati, ma anche delle loro funzioni e le destinazioni d’uso; parallelamente si è sviluppata l’analisi del linguaggio formale delle architetture, allo scopo sia di definire le cronologie degli edifici sia di inserirli nel più ampio fenomeno della decorazione architettonica microasiatica, rintracciandone gli eventuali modelli, anche in rapporto al complesso problema dell’attività delle maestranze, per fornire un quadro aggiornato delle modalità di impiego dell’ordine ionico a Hierapolis di Frigia nel corso dell’età imperiale. La ricerca ha affrontato i due complessi santuariali del centro cittadino: nel Santuario di Apollo vengono analizzati il Tempio C, una serie di eccezionali capitelli ionici con collarino decorato e un consistente gruppo di elementi architettonici riferibili ad un portico di temenos (di ordine corinzio); nel Ploutonion si sono indagati alcuni materiali riferibil invece ad un portico ionico, posto a coronamento del theatron rituale.This doctoral research is part of the activities of MAIER – Italian Archaeological Mission in Hierapolis of Phrygia (Pamukkale, Turkey) and of the investigation field on the ancient architecture in Asia Minor. Some buildings and architectural blocks of Ionic order, recently discovered, are analyzed in order to achieve a reconstruction of the monuments, not only of the plan and elevation, but also of the ancient functions and use of the buildings. The stylistic analysis is also very important, to determine the chronology of the monuments and to relate the Ionic architecture of Hierapolis with the other urban centres in Asia Minor and their architectural tradition during the Imperial period. The dissertation is focused on both the sanctuaries of Hierapolis: in the Sanctuary of Apollo, the research analyzes the Temple C, a series of Ionic capitals with decorated hypotrachelion, and a group of architectural blocks from a (Corinthian) temenos portico; in the Ploutonion, the focus is on a series of blocks from an Ionic Stoa, related to the cultic theatre.
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BOZZA, SARA. "ARCHITETTURA IONICA A HIERAPOLIS DI FRIGIA." Doctoral thesis, Università Cattolica del Sacro Cuore, 2016. http://hdl.handle.net/10280/10487.
Full textAbstract:
La ricerca di dottorato si inserisce nel quadro delle attività della MAIER – Missione Archeologica Italiana a Hierapolis di Frigia (Pamukkale, Turchia) e nel filone degli studi di architettura antica relativi ai complessi edilizi dei centri microasiatici. Vengono analizzati, in particolare, alcuni edifici e materiali architettonici di ordine ionico emersi dalle recenti indagini di scavo, allo scopo di fornire una ricostruzione dei monumenti nella planimetria e negli alzati, ma anche delle loro funzioni e le destinazioni d’uso; parallelamente si è sviluppata l’analisi del linguaggio formale delle architetture, allo scopo sia di definire le cronologie degli edifici sia di inserirli nel più ampio fenomeno della decorazione architettonica microasiatica, rintracciandone gli eventuali modelli, anche in rapporto al complesso problema dell’attività delle maestranze, per fornire un quadro aggiornato delle modalità di impiego dell’ordine ionico a Hierapolis di Frigia nel corso dell’età imperiale. La ricerca ha affrontato i due complessi santuariali del centro cittadino: nel Santuario di Apollo vengono analizzati il Tempio C, una serie di eccezionali capitelli ionici con collarino decorato e un consistente gruppo di elementi architettonici riferibili ad un portico di temenos (di ordine corinzio); nel Ploutonion si sono indagati alcuni materiali riferibil invece ad un portico ionico, posto a coronamento del theatron rituale.This doctoral research is part of the activities of MAIER – Italian Archaeological Mission in Hierapolis of Phrygia (Pamukkale, Turkey) and of the investigation field on the ancient architecture in Asia Minor. Some buildings and architectural blocks of Ionic order, recently discovered, are analyzed in order to achieve a reconstruction of the monuments, not only of the plan and elevation, but also of the ancient functions and use of the buildings. The stylistic analysis is also very important, to determine the chronology of the monuments and to relate the Ionic architecture of Hierapolis with the other urban centres in Asia Minor and their architectural tradition during the Imperial period. The dissertation is focused on both the sanctuaries of Hierapolis: in the Sanctuary of Apollo, the research analyzes the Temple C, a series of Ionic capitals with decorated hypotrachelion, and a group of architectural blocks from a (Corinthian) temenos portico; in the Ploutonion, the focus is on a series of blocks from an Ionic Stoa, related to the cultic theatre.
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Bernhem, Kristoffer. "How ionic are ionic liquids?" Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-41033.
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Ionic liquids are continuously finding more and more applications, both in research and in the industry. Many attempts have been made to find parameters that could be used to describe all ionic liquid systems. Five years ago a Japanese group applied the work of Gutmann on ionic liquids to use ionic association to describe solvation effects. The group calculated ionic association from conductivity and diffusion measurements. This report presents a direct approach through electrophoretic NMR to measure ionic association in ionic liquids. The report contains a brief introduction to ionic liquids and their properties as well as a short explanation of Nuclear Magnetic Resonance (NMR) spectroscopy, diffusion NMR and a more detailed explanation of electrophoretic NMR (eNMR). Experimental setups, taken from previous work by the NMR group at Physical Chemistry KTH, have been modified to allow for measurements in ionic liquid systems. The report discusses the issues that can arise when measuring eNMR in ionic liquids and suggests solutions. The method developed is principally built upon experiments on 1-butyl-3-methyl-imidazolium trifluoroacetate and is directly applicable to other ionic liquid systems. For more viscous systems than the one investigated here, slight changes will need to be made, as explained in the report. In order to evaluate the method developed during the project the degree of association for 1-butyl-3-methyl-imidazolium trifluoroacetate has been calculated from experimental results and results in similar values as reported by Tokuda et al.. Furthermore, the temperature variation due to Joule heating during a complete eNMR experiment was also investigated by observing change in chemical shift.
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Barros, Davison Storai de. "Estudo espectroscopico e morfologico de filmes automontados de azocompostos." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249464.
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Orientador: Teresa Dib Zambon AtvarsDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Neste trabalho são estudadas as propriedades fotoquímicas e morfológicas de filmes automontados compostos de um polieletrólito fraco e azocorantes em função das condições impostas nas soluções de origem, como o pH, a força iônica e tamponamento. Na automontagem, os filmes são fabricados pela deposição de camadas alternadas de dois materiais, de cargas elétricas opostas, a partir de suas soluções aquosas em um substrato de vidro. Os materiais usados foram o polieletrólito catiônico hidrocloreto de poli(alilamina) (PAH) e três azocorantes aniônicos: Vermelho do Congo (CR), Ponceau SS (PSS) e Alaranjado de Metila (MO). Foram fabricados filmes de PAH/CR, PAH/PSS e PAH/MO. Para avaliar somente o efeito do pH, foram usados três valores de pH (3, 7 e 10). Para verificar o efeito da força iônica, foram usadas soluções aquosas de cloreto de potássio em diferentes concentrações e, para verificar a influência de tampão, foram usados três sistemas tampão, um para cada valor de pH. Foram usadas as técnicas de espectroscopia UV-vis e turbidimetria para investigar as propriedades espectroscópicas das soluções, dos filmes e a solubilidade do PAH. Foi utilizada a técnica de microscopia de força atômica para verificar a morfologia do filme. Observa-se que a deposição dos corantes e do PAH no filme depende de suas densidades de carga, bem como da presença de outras espécies iônicas em solução. Tanto um aumento do pH como a presença de contra-íons, leva a uma redução da carga do PAH e causa um aumento de sua adsorção no filme, acompanhado de um aumento de rugosidade superficial. Porém, a primeira condição pode ou não diminuir as cargas dos corantes e a segunda enfraquece a atração eletrostática, reduzindo as suas deposições. As interações do par corante-PAH induzem a agregação dos corantes em solução e nos filmes. As diferenças estruturais dos corantes são igualmente importantes, pois o CR e o PSS são os que mais se depositam e apresentam diferentes comportamentos de deposição em função do pH. Verifica-se também que o PAH interage distintamente com diferentes contra-íons, o que pode ser explicado considerando-se a especificidade iônica e não o simples conceito de força iônica
Abstract: In this work, the photochemical and morphological properties of layer-by-layer self¿assembly films made of a weak polyelectrolyte and azodyes are studied in dependence of the solution¿s pH, ionic strength and buffering. In self-assembly technique, films are made from deposition of alternate layers of two compounds, which have opposite electrical charges, from their solutions onto a glass substrate. We employed the polyelectrolyte poly(allylamine) hydrochloride (PAH) which is positively ionized when in aqueous solution and the three different anionic azodyes: Congo Red (CR), Ponceau SS (PSS) and Methyl Orange (MO). Films of PAH/CR, PAH/PSS and PAH/MO were prepared. To investigate only the pH effect, three pH values were used (3, 7 and 10). To investigate the ionic strength, potassium chloride aqueous solution at different concentrations were used and to verify the buffer effect, three buffer systems were used, one for each pH. The UV-Vis Spectroscopy and Turbidimetry were employed to study the spectroscopic properties of the solutions, films and PAH solubility. The Atomic Force Microscopy was used to verify the film morphology. One observes that the dyes and PAH deposition depend on their charge densities as well the presence of other ionic species. An increase in solution¿s pH and/or the presence of counter-ions reduces PAH¿s charge increasing its adsorption on film, accompanied by a higher surface roughness. Differently, the first condition can or cannot reduce the dye¿s charge and the second weakens the electrostatic interaction, reducing dye adsorption. The pair dye-PAH interactions induces the dye aggregation both in solution and film. The structural differences between dyes are equally important, as CR and PSS are the ones that adsorb most and show different deposition behavior in function of solution¿s pH. Also, one verifies that PAH interacts distinctly with different counter-ions, a fact that can be explained considering ionic specificity and not by the simple concept of ionic strength
Mestrado
Físico-Química
Mestre em Química
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Avala, Usha Kranthi. "Ionic Conductivity in Non-Ionic Compounds." TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1279.
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The main objective of this work is to investigate the ionic conductivity of the drugs under certain conditions and also to compare the ionic conductivities of drugs determined by single surface sensors and parallel plate sensors. The ionic conductivity of various materials at their pre-melt and melt states are studied in order to further study a recently discovered phenomenon. Polar solids like Lidocaine, Ketoconazole, Procainamide and Nifedipine were examined in this study. Experimental studies show an increase in ionic conductivity in both pre-melt (20 -30 °C below melting temperature) and melt transition regions. Results of ionic conductivity of both parallel plate and single surface sensor at different frequencies are compared. At 1000 Hz, all the samples show an increase in ionic conductivity with both parallel plate and single surface sensor, but at 0.1 Hz frequency, no increase in ionic conductivity is observed with parallel plate sensor except for Nifedipine.
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LATINI, GIULIO. "Bio-based ionic liquids and poly(ionic liquid)s for CO2 capture." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2912980.
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Figueira, Sebastiao Miguel. "Ionized regions and star formation in the galaxy." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0291.
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Ma thèse est centrée sur l'étude de l'interaction entre les étoiles massives et le milieu environnant. Je suis particulièrement intéressé par l'effet qu'ont ces étoiles sur les jeunes objets stellaires observés autour d'elles. Les étoiles massives forment des régions d'hydrogène ionisé (HII) dont l'expansion supersonique conduit à la formation d'une couche de gaz et de poussières où les conditions paraissent favoriser la formation stellaire. Mon travail consiste à étudier les propriétés des jeunes objets stellaires autour de ces régions HII et à savoir si la région HII a influencé positivement la formation de ces sources.En utilisant les données Herschel, issues des programmes HOBYS et Hi-GAL, complétées par d'autres observations, j'ai étudié deux régions HII galactiques (RCW~79 et RCW~120) afin de caractériser la formation stellaire observée à leurs frontières. Pour étudier l'impact de la photoionisation, j'ai calculé le taux de formation stellaire (SFR) pour ces deux régions. Cette grandeur suggère que RCW~79 et RCW~120 sont des régions de formation stellaire actives malgré leur relative faible densité surfacique de gaz. Une nouvelle étude de la région G345 est en cours. Cette région HII est située au-dessus du plan galactique et forme activement des étoiles. Avec les données disponibles, les propriétés de la formation stellaire seront discutées. Cette étude nous donne l'opportunité de mieux comprendre les effets de la photoionisation en dehors du plan galactique. Cette région viendra augmenter notre échantillon de régions HII, ce qui est nécessaire pour avoir une vision globale des mécanismes en jeu et pour mieux comprendre l'efficacité de la formation stellaireMy PhD thesis deals with the study of the interaction between high mass stars and their surrounding medium. I am particularly interested in the way high-mass stars affect the young stars observed around them. Massive stars form ionized (HII) regions which, during their supersonic expansion, lead to the formation of a layer of gas and dust where the conditions seem to favor star formation. My work aims at understanding the properties of star formation around Galactic HII regions.Using \herschel\, data (HOBYS and Hi-GAL programs) complemented with ancillary data, I studied two Galactic \HII\, regions (RCW~79 and RCW~120) to characterize the star formation observed at their edges. To study the impact of the ionization pressure, I computed the Star Formation Rate (SFR), which suggests that RCW~79 and RCW~120 are active star-forming regions despite their low gas surface density.A new study about the G345 region is in progress. This HII region is located above the Galactic plane and is actively forming stars. With the data available, the star formation's properties is being derived such as the spatial distribution of clumps, their stellar content, the SFR and CFE. This new study offers another opportunity to better understand the photoionization feedback out of the Galactic plane. Moreover, this will complete the sample of detailed studies of \HII\, regions, allowing us to obtain a global view of the mechanisms at play and of the efficiency of star formation in these regions
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Paschalidi, M. "Constructing Ionian identities : the Ionian Islands in British official discourses, 1815-1864." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19415/.
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Utilising material such as colonial correspondence, private papers, parliamentary debates and the press, this thesis examines how the Ionian Islands were defined by British politicians and how this influenced various forms of rule in the Islands between 1815 and 1864. It explores the articulation of particular forms of colonial subjectivities for the Ionian people by colonial governors and officials. This is set in the context of political reforms that occurred in Britain and the Empire during the first half of the nineteenth-century, especially in the white settler colonies, such as Canada and Australia. It reveals how British understandings of Ionian peoples led to complex negotiations of otherness, informing the development of varieties of colonial rule. Britain suggested a variety of forms of government for the Ionians ranging from authoritarian (during the governorships of T. Maitland, H. Douglas, H. Ward, J. Young, H. Storks) to representative (under Lord Nugent, and Lord Seaton), to responsible government (under W. Gladstone’s tenure in office). All these attempted solutions (over fifty years) failed to make the Ionian Islands governable for Britain. The Ionian Protectorate was a failed colonial experiment in Europe, highlighting the difficulties of governing white, Christian Europeans within a colonial framework.
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Ochoa, Becerra Erika Abigail. "Aceleração da nitretação iônica pela nanoestruturação de superfícies metálicas induzidas por bombardeio com gases nobres." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277721.
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Orientador: Fernando AlvarezTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: A presente tese trata o estudo as propriedades físicas resultantes em sistemas metálicos com superfícies nanoestrutura as pelo bombardeio com gás nobre e posteriormente nitretados com técnicas basea as em plasma. A busca e novas condições e tratamento que aumentem a velocidade a ifusão o nitrogênio é e grande interesse para a modificação e superfícies metálicas. Para isto, o pré-tratamento a superfície o material, através e métodos e refinamento os grãos a superfície, é fundamental na melhora a incorporação e nitrogênio no material. Este trabalho visa o estudo e sistemas basea os em ferro, especialmente aços e interesse tecnológico, com superfícies refinadas até a escala nanométrica e submeti os ao processo e nitretação. Neste caso, a superfície a amostra considera a po e ser nanoestrutura a por bombar eiodiônico com gases nobres ("atomic attrition") e posteriormente nitreta a usan o feixe e íons. O material escolhi o para o presente trabalho é o aço enomina o AISI 4140, um aço e baixa liga. O tratamento superficial ("atomic attrition") prévio ao processo e nitretação possibilita o aumento o conteúdo e nitrogênio em profundidade permitindo ainda que a nitretação possa ser realizada a temperaturas relativamente mais baixas (T ~ 300 °C). A caracterização as amostras pré-trata as e/ou nitretadas é realizada in-situ por espectroscopia e elétrons fotoemitidos garantindo condições únicas para o estudo o fenômeno e nanoestruturação e sua influência na ifusão o nitrogênio. Outras técnicas usuais e caracterização utiliza as foram a nano-in entação, raios-X (em nosso grupo e no LNLS) e microscopia óptica e eletrônica. Os resultados indicam o sucesso na nanoestruturação a superfície as amostras pela formação e caminhos e rápida difusão e nitrogênio e assim aumentando a dureza resultante o material
Abstract: The present thesis treats the stu y of the physical resultant properties in metallic systems with nano-structure surfaces by the bombar ment with noble gas an subsequently nitri e with techniques base on plasma. The search for new con itions of treatment that increase the spee of diffusion of the nitrogen is of great interest for the modification of metal surfaces. For this, the pre-treatment of the material surface, through methods of refinement of the grains at the surface, is fundamental in the improvement of the incorporation of nitrogen in the material. This work aims at the study of systems base on iron, especially steels of technological interest, with surfaces refine up to the nanometric scale an subjecte to the nitriding process. In this case, the surface of the considere sample can be nano - structure by ionic bombar ment with noble gases ("atomic attrition") an subsequently nitride using bundle of ions. The material chosen for the present work is the steel AISI 4140, a steel of low alloy. The superficial treatment ("atomic attrition") prior to the process of nitriding makes possible the increase of the content of nitrogen in epth allowing still that nitriding could be carrie out to relatively lower temperatures (T ~ 300 °C). The characterization of the samples pre-treate an / or nitride is carrie out in-situ by spectroscopy of photo-emitte electrons guaranteeing singular conditions for the study of the phenomenon of nano-structuring an its influence in the nitrogen iffusion. Other usual techniques of characterization use were nano - in dentation, X-rays (in our group an at LNLS), optical an electronic microscopy. The results indicate the success in the nano - structuring of the sample surface for the formation of ways of quick diffusion of nitrogen an so increasing the resultant har ness of the material
Doutorado
Física da Matéria Condensada
Doutor em Ciências
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Ariyadi, Hifni Mukhtar. "Thermodynamic study on absorption refrigeration systems using ammonia/ionic liquid working pairs." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/396178.
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This thesis was aimed to analyse the feasibility and the performance of ionic liquids as an absorbent for ammonia refrigerant in absorption refrigeration systems. Ionic liquids, novel and tailor-made absorbents, can be used with ammonia as working pairs for absorption refrigeration cycles and give some advantages such as elimination of the rectification process in ammonia/water systems. The performances of several ammonia/ionic liquid mixtures working pair available in the literature were then theoretically studied and analysed for absorption refrigeration applications using selected NRTL model. In addition, new selected ammonia/ionic liquid mixtures working pair for absorption refrigeration applications were also theoretically studied and analysed. The results show that the coefficient of performance (COP) of the absorption systems working with ammonia/ionic liquid working fluids were about similar when compared with ammonia/LiNO3 at same cooling capacity and operation conditions. Among all of selected ammonia/ionic liquid working fluids studied in this thesis, only [N1113][NTf2] presented higher COP that that of ammonia/LiNO3 at certain operation conditions. The COP of the systems with other ionic liquids as absorbents follows an order of [EtOHmim][BF4] > [N111(2OH)][NTf2] > [EtOHmim][NTf2] at all operation conditions. Finally it can be concluded that the ionic liquid has a great potential to be an alternative absorbent for ammonia refrigerant. The ammonia/ionic liquid working fluid can provide competitive performance in comparison with conventional absorbent for ammonia refrigerant. However, some drawbacks were still remains to be solved such as relatively low solubility of ammonia into ionic liquids which affects to the solution circulation mass flow ratio and relatively high viscosity of ionic liquid in comparison with other conventional absorbent which may affects to the performance of absorber and solution pump.
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Churchill, Layne Russell. "Trapping triply ionized thorium isotopes." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37161.
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Cold trapped ions have many applications in quantum information science and precision metrology. In this thesis, we present progress toward two objectives involving ions confined to linear RF traps: the strong coupling of Ba+ ions with a high finesse optical cavity, and the observation of an optical nuclear transition in 229Th3+. In pursuit of the first objective, a novel high-temperture vapor cell for the spectroscopy of neutral barium was constructed. Using this vapor cell, a new technique for isotope-selective photoionization loading of Ba+ in an ion trap was developed. In pursuit of the second objective, techniques ultimately to be used in creating, trapping, and observing 229Th3+ are studied using 232Th3+. Ion traps are loaded with 232Th3+ via laser ablation of thorium targets. 232Th3+ is detected optically using laser-induced fluorescence and electronically using a channel electron multiplier. A technique for creating ablation targets from trace quantities of thorium nitrate is presented. The primary loss mechanisms of Th3+, charge exchange and chemical reactions, are studied.
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Marinou, Pénélope. "Le tourisme dans l'archipel ionien." Aix-Marseille 1, 1993. http://www.theses.fr/1993AIX10017.
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Le tourisme dans l'archipel ionien (grece occidentale), qui est compose de vingt iles et ilots, presente un interet particulier. Assez developpe au nord, sur l'ile de corfou, des 1970, il n'acquiert une importance dans le reste de l7archipel qu'a partir des annees quatre vingts quand les departements ioniens se classent parmi les regions les plus touristiques de la grece. Les iles ioniennes, caracterisees par la presence de grandes iles, la proximite a la terre ferme et la fertilite du sol, supportent une population agricole dont les relations avec la mer sont minimes. Le tourisme dans les iles ioniennes doit son developpement surtout a l'intervention de l'etat dans le domaine de l'infra-structure (aeroports, ports,) et a l'interet qu'il a suscite chez les insulaires. Le flux touristique est compose principalement d'etrangers et, en particulier, d'anglais. C'est un flux a vocation balneaire, compose essentiellement de personnes plutot jeunes provenant de classes moyennes et aisees, dont la presence a conduit a developpement de stations touristiques mononucleaires. Le rayonnement national et europeen de ces stations justifie l'existence d'une region touristique. C'est un espace nettement hierarchise dans lequel nous observons quatre centres touristiques autour desquels gravitent plusieurs centres secondaires. Le tourisme a eu des effets possitifs sur l'evolution demographique et l'emploi mais, par manque de mesures appropriees, des effets plutot negatifs sur l'environnement.
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Yang, Junhong. "GLASS FORMATION BEHAVIOR AND IONIC CONDUCTIVITY OF IONIC LIQUIDS AND POLYMERIC IONIC LIQUID: INSIGHT FROM MOLECULAR SIMULATION." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1494886213137829.
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Coles, Samuel. "Interfacial nanostructure of solvate ionic liquids and ionic liquid solutions." Thesis, University of Oxford, 2018. https://ora.ox.ac.uk/objects/uuid:89c797e4-e000-4c8c-b6b8-ffa5ed202a4d.
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The technology employed by human beings for the generation, storage and usage of energy is presently undergoing the fastest and most profound change since the industrial revolution. The changes in the generation and usage of energy necessitate the development of new methods of energy storage. In these systems, electrochemical energy storage will play a crucial role and to this end new electrolytes need to be explored to complement these changes. One such class of liquids is ionic liquids, a class of salts that are molten at room temperature. These liquids have a broad applicability to batteries and supercapacitors. This thesis details work where molecular dynamics simulations have been used to explore the nanostructure of ionic liquids and their mixtures with various molecular solvents at simplistic electrodes. The thesis has two broad sections. The first is covered in Chapter 3, and explores the nanostructure of ionic liquid propylene carbonate solutions, developing a framework through which these nanostructures can be understood. The section concludes that the increasing dilution of ionic liquids decreases the surface charge at which the characteristic ionic liquid oscillatory interfacial structure gives way to a different structure featuring monotonic charge decay. The behaviour of ionic liquids at interfaces is found to be correlated to ion size and type, as well as concentration. A wide divergence in the observed behaviour is shown at positive and negative electrodes due to the asymmetry of propylene carbonate. The second section, consisting of two chapters, explores the interfacial nanostructure of solvate ionic liquids using two different boundary conditions to model the electrode. This work is the first simulation of solvate ionic liquids at electrified interfaces. This section will explore the effect of electrode model on the behaviour of these ionic liquids at the electrode. Chapter 4 uses a fixed charge electrode, whereas Chapter 5 uses one with a fixed potential. The section concludes that regardless of electrode model, the idealised portrait of a solvate ionic liquid - one where the liquid behaves exactly as an aprotic ionic liquid - is not applicable. In Chapter 4's exploration of fixed charged electrodes, the formation of 2 glyme to lithium complexes contradicts the idealised portrait of the liquid. A different change is observed in Chapter 5's exploration of fixed potential electrodes, with both lithium glyme and lithium anion clusters forming at the interface. The key difference between the two studies is that lithium does not coordinate to the electrode in the fixed charge simulations, while in the fixed potential case it does. At the end of Chapter 5 the results are compared against experimental data, with the efficacy of the two models discussed. The aim of both studies is to look at the nanostructure of ionic liquids, when the symmetry between co-ion and cation repulsion - and related effects - is broken by the presence of a non ionic constituent in the liquid.
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Kattner, Hendrik. "Radical Polymerization Kinetics of Non-Ionized and Fully-Ionized Monomers Studied by Pulsed-Laser EPR." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://hdl.handle.net/11858/00-1735-0000-0028-879B-7.
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Le, Goff Johan. "Evolution tectono-sédimentaire du système carbonaté "Plateforme Apulienne - Bassin Ionien" au Crétacé supérieur dans le sud de l'Albanie : faciès, géométries, diagénèse et propriétés réservoirs associées." Thesis, Bordeaux 3, 2015. http://www.theses.fr/2015BOR30024/document.
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L’intérêt scientifique porté depuis plusieurs décennies au développement des plateformes carbonatées tropicales s’explique par la complexité des facteurs de contrôle de la sédimentation, qui montre une influence de la tectonique, du climat, de l’eustatisme, de l’hydrodynamisme etc… Les plateformes carbonatées ne sont pas seulement des environnements enclins à accumuler des sédiments, mais sont aussi de prolifiques « usines » à carbonates qui produisent davantage que ce qu’elles peuvent stocker. Les sédiments en excès sont transférés vers le bassin profond. Ainsi, les transitions plateforme – bassin illustrent les interactions entre production carbonatée in-situ, transfert, et accumulation sédimentaire issue de la re-sédimentation. Dans le sud-ouest de l’Albanie, la série carbonatée du Crétacé Supérieur est composée de dépôts sédimentaire de plateforme et de bassin. Ces successions sont à présent intégrées dans le système chevauchant de la chaîne Dinarides - Hellénides, dont la mise en place est contemporaine d’une phase de déformation orogénique Plio-Holocène. La paléogéographie de la région péri-Adriatique au Crétacé Supérieur révèle une juxtaposition de méga-plateformes et de bassins adjacents dont le remplissage est en partie conditionné par la remobilisation gravitaire des sédiments de la bordure de plateforme. Les investigations sont menées sur cinq zones d’étude. Elles intègrent des descriptions faciologiques macro- et microscopiques pour chacune des huit successions étudiées. Les unités définies font l’objet d’une cartographie à l’échelle de la zone d’étude qui précise l’architecture stratigraphique du système. La datation des dépôts repose sur une étude biostratigraphique, elle est renforcée par les données chronostratigraphiques des isotopes du strontium. Sur la plateforme, les descriptions faciologiques sont appuyées par des méthodes complémentaires de pétrographie (cathodoluminescence, épifluorescence, microscopie électronique à balayage), de pétrophysique (porosimétrie à injection mercure) et de géochimie (isotopes stables du carbone et de l’oxygène) visant à révéler la dynamique de sédimentation et les propriétés réservoir de la succession.Les conditions de sédimentation sont précisées, i) sur la plateforme, dix faciès spécifiques sont identifiés, représentatifs de contidions de dépôt supra-, inter-, et subtidales. Ils s’intègrent dans des motifs d’empilement distinctifs (small-scale sequences) qui attestent le caractère cyclique de la sédimentation, contrôlé par des fluctuations haute-fréquence et basse amplitude du niveau marin relatif; ii) dans le bassin, quatorze faciès sont classés suivant le mécanisme de transport sédimentaire dominant. La répartition spatiale des dépôts permet d’identifier la provenance et les sources préférentielles du matériel calci-clastique. L’évolution tectono-sédimentaire plateforme – bassin au Crétacé Supérieur est déterminée par deux séquences: i) du Cénomanien au Turonien, la sédimentation de plateforme est caractérisée par l’aggradation plus de 700 mètres de faciès intertidaux organisés en séquences (small-scale sequences) émersives ou sub-émersives. Aucun transfert significatif n’est attesté dans le bassin adjacent, témoignant d’une relative stabilité du système évoluant dans un contexte subsident ; ii) l’intervalle Coniacien – Santonien marque l’installation d’une plateforme à rudistes favorable au transfert sédimentaire. Ce dernier se traduit par une progradation marquée des dépôts gravitaires dans le bassin pendant le Campanien. Cette dynamique de transfert est accentuée par la mise en place de slumps résultants du démantèlement tectonique de la bordure de plateforme au Campanien Supérieur et MaastrichtienThe evolution of tropical carbonate platforms depends on complex interacting factors influencing the sedimentation, such as tectonism, climate, eustacy, hydrodynamism etc… Due to this complexity, it has been of scientific interest for decades. Carbonate platforms are not only prone to accumulate sediments, but also represent prolific carbonates “factories” producing more than they can store on their tops. Excess sediments are shed basinward. Platform-to-basin transitions exemplify interactions between in-situ carbonate production, transfer and sedimentary accumulations resulting from re-sedimentation. In south-west Albania, the Upper Cretaceous carbonate series are made up of platform and basinal deposits. Sedimentary successions are presently integrated in the Dinarides-Hellenides fold-and thrust belt that originate from a Plio-Holocene phase of the Alpine Orogeny. The paleogeographic setting during the Late Cretaceous reveals a juxtaposition of mega-platforms and adjacent basins, partly filled with sediments derived from the shelf edge. Our scientific investigations focused on five study areas. Macro- and microfacies descriptions are provided for eight platform and basin successions. Sedimentary units are defined and mapped on each study area, supporting the stratigraphic reconstruction of the system. Dating is based on biostratigraphy and supported by strontium-isotope data. Regarding platform deposits, facies descriptions are seconded by complementary methods of petrography (cathodoluminescence, epifluorescence, scanning electron microscopy), petrophysics (mercury intrusion porosimetry), and geochemistry (stable carbon and oxygen isotopes), aiming to precise the sedimentation dynamics and reservoir properties of the succession. The sedimentation conditions are specified: i) within the platform, ten specific facies are identified, precising the depositional setting that comprise supra-, inter- and subtidal environments. These facies are integrated in distinctive stacking patterns (small-scale-sequences) pointing to a cyclic sedimentary dynamic controlled by high-frequency and low-amplitude sea level changes; ii) the basinal deposits comprise fourteen facies classified according to the dominant grain-support mechanism. Spatial distribution of the deposits allowed identifying the provenance and preferential sources of calciclatic sediments. The tectono-sedimentary evolution of the platform-to-basin system during the Late Cretaceous can be subdivided into two sequences: i) from the Cenomanian to the Turonian, the platform sedimentation is characterized by a substantial aggradation (700 meters) of intertidal small-scale sequences. No significant transfer was evidenced in the adjacent Ionian Basin, pointing to stable conditions in a subsiding context; ii) the Coniacian-Santonian interval evidences the establishment of a rudist platform massively shedding sediments basinward during the Campanian. A clear progradation of gravity-flow deposits is attested during this period. During the Upper Campanian and Maastrichtian, this transfer is accentuated by the setting of tectonically-triggered slumps resulting from the dismantling of the platform edge
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Santos, Júnior Garbas Anacleto 1988. "Desenvolvimento de um novo eletrólito polimérico baseado num derivado de PEO e metais de transição para aplicação em dispositivos fotoeletroquímicos." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248375.
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Orientador: Ana Flávia NogueiraDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Neste trabalho são apresentados os resultados da preparação e caracterização de eletrólitos poliméricos usando matriz polimérica de um copolímero derivado de PEO - poli (óxido de etileno-co-2-(2-metoxietoxi) etil glicidil éter) - P(EO-EM) - visando à substituição do par redox, I/I3 , usualmente mais comum em células solares do tipo DSSC, por pares de íons de metais de transição, como Fe e Co . Os eletrólitos foram preparados utilizando razões mássicas fixas de P(EO-EM):GBL de 30-70%. Para os eletrólitos de ferro foram utilizados os sais de FeCl2 + FeCl3·6H2O e para os eletrólitos de cobalto CoCl2 · 6H2O + CoF3. Em ambos os casos foram estudados razões molares entre os cátions de valência II:III de 1:1 e 10:1. Diferentes razões mássicas foram estudadas, sendo estas de 2, 5, 8 e 16% para os eletrólitos de ferro e de 1, 2, 3 e 5% para os eletrólitos de cobalto. Valores máximos de condutividade para os eletrólitos contendo sais de ferro foram de 1,88 x 10 e 1,40 x 10 S cm-1, para concentrações de 16% de sal e razões de 1:1 e 10:1 (Fe:Fe), respectivamente. Enquanto que no caso dos eletrólitos contendo cátions de cobalto foram de 1,41 x 10 e 1,16 x 10 S cm, para concentrações de 5% de sal e razões de 1:1 e 10:1 (Co:Co), respectivamente. Testes de PIA- Photoinduced Absorption Spectroscopy mostraram a eficiência do par redox Fe para regeneração dos corantes L0, N719, D35 e Z907. Entretanto, os mesmos testes mostraram a eficiência do par redox Co para regeneração somente do corante L0. A confecção de dispositivos do tipo DSSC com eletrólitos contendo sais de Fe e Co apresentaram resultados insatisfatórios, possivelmente relacionado com a alta taxa de recombinação do elétron ejetado no TiO2 com os mediadores redox
Abstract: This work presents the results of the preparation and characterization of polymer electrolytes using polymeric matrix of a PEO copolymer-poly (ethylene oxide-co-2-(2-methoxyethoxy) ethyl glycidyl ether) - P (EO-EM) - in order to substitute the redox couple , I-/I3-, usually most common mediators in DSSC solar cells, by transition metal ions pairs, such as Fe and Co . The electrolytes were prepared using fixed P(EO-EM) : GBL weight ratios of 30-70 % . The iron electrolytes were prepared using FeCl2 + FeCl3 o 6H2O salts and CoCl2 o 6H2O + CoF3 were used for the cobalt electrolytes. In both cases, it was studied the molar ratios between cations with valence of II: III of 1:1 to 10:1. Different weight ratios were studied, 2 , 5, 8 and 16% for iron electrolytes and 1 , 2, 3 and 5% for the cobalt electrolytes . Maximum conductivity values for the electrolyte containing iron salts were 1.88 x 10 and 1.40 x 10 S cm at salts concentrations of 16 % and ratios from 1:1 to 10:1 (Fe:Fe), respectively. While in the case of electrolyte containing cobalt cations the conductivity values were 1.41 x 10 and 1.16 x 10 S cm -1 at salts concentrations of 5 % and ratios from 1:1 to 10:1 ( Co:Co), respectively . PIA tests - Photoinduced Absorption Spectroscopy- showed the efficiency of the FeII/III redox couple for the regeneration of L0 , N719 , Z907 and D35 dyes. However, the same tests have shown that the CoI redox couple were only able to regenerate the L0 dye. The DSSC devices with electrolytes containing Fe and Co salts showed unsatisfactory results, possibly related to the high rate of recombination of the electron ejected in TiO2 with the redox mediators
Mestrado
Quimica Inorganica
Mestre em Química
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Adamová, Gabriela. "Phosphonium ionic liquids." Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.554341.
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This work was financially supported by Cytec Industries, Canada, providing a primary focus on phosphonium ionic liquids, their synthesis and characterisation. Four different series of tetraalkylphosphonium ionic liquids were studied, alkyltrioctyl-, alkyltrihexyl-, alkyltributyl-phosphonium chlorides and alkyltrihexylphosphonium bistriflamides, with variation of the alkyl chain from methyl to tetradecyl. This thesis describes their synthesis, their detailed characterisation (including spectroscopic, analytical and structural methods), and analysis of the relationship between their structure and their physical properties, and comparison with their ammonium analogues. Most of the salts prepared were new, and this is the first systematic study of coherent series of phosphonium ionic liquids. One of the series ([P8 8 8 n ]CI) exhibited an alternation effect in both, density and viscosity trends, which is the first evidence of such behaviour for any class of ionic liquids. This effect is attributed to the even and odd alkyl chain change in the cation, which has been previously observed in other classes of molecular organic compounds. Although the alternation effect was not witnessed in any other series of phosphonium ionic liquids (for the other chloride series, the number of salts liquid at room temperature was a restriction, while lack of zig-zag trend in the bistriflamide series might be pointing to the influence of anion on such behaviour), this finding (in combination with literature data and crystal structure presented for [P4 4 43]Cl) is pointing to possible interesting solid/glass-liquid rearrangements. The tetraalkylphosphonium ionic liquids were found to have superior thermal stability and viscosity to their tetraalkylammonium analogues. A part of this work was performed in cooperation with the research group of Dr. Cristina S. Pereira in Portugal: this focussed on ecotoxicity studies of [P4 4 4 n]Cl. These studies revealed that toxicity dramatically changes with changing alkyl substituent, but also suggested the nature of the mechanism of toxicity. This is the first study where the interaction of ionic liquids with cellular boundaries has been examined with fluorescence microscopy.
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Akle, Barbar Jawad. "Multilayer Ionic Transducers." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31733.
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A transducer consisting of multiple layers of ionic polymer material is developed for applications in sensing, actuation, and control. The transducer consists of two to four individual layers each approximately 200 microns thick. The transducers are connected in parallel to minimize the electric field requirements for actuation. The tradeoff in deflection and force can be controlled by controlling the mechanical constraint at the interface. Packaging the transducer in an outer coating produces a hard constraint between layers and reduces the deflection with a force that increases linearly with the number of layers. This configuration also increases the bandwidth of the transducer. Removing the outer packaging produces an actuator that maintains the deflection of a single layer but has an increased force output. This is obtained by allowing the layers to slide relative to one another during bending. A Finite Element Analysis (FEA) method capable of modeling the structure of the multilayer transducers is developped. It is used to model the interfacial friction in multilayer transducers.
Experiments on transducers with one to three layers are performed and the results are compared to Newbury's equivalent circuit model, which was modified to accommodate the multilayer polymers. The modification was performed on four different boundary conditions, two electrical the series and the parallel connection, and two mechanical the zero interfacial friction and the zero slip on the interface.
Results demonstrate that the largest obstacle to obtaining good performance is water transport between the individual layers. Water crossover produces a near short circuit electrical condition and produces feedthrough between actuation layers and sensing layers. Electrical feedthrough due to water crossover eliminates the ability to produce a transducer that has combined sensing and actuation properties. Eliminating water crossover through good insulation enables the development of a small (5 mm x 30 mm) transducer that has sensing and actuation bandwidth on the order of 100 Hz.
Due to the mechanical similarities of ionic transducers to biological muscles and their large flapping displacement capabilities we are studying the possibility of their use in flapping Micro Air Vehicle (MAV) application, as engines, controllers and sensors. The FEA modeling technique capable is used to design two ionic polymers actuated flapping wings.Master of Science
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Davidson, Jacob Daniel. "Actuation and Charge Transport Modeling of Ionic Liquid-Ionic Polymer Transducers." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/31204.
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Ionic polymer transducers (IPTs) are soft sensors and actuators which operate through a coupling of micro-scale chemical, electrical, and mechanical mechanisms. The use of ionic liquid as solvent for an IPT has been shown to dramatically increase transducer lifetime in free-air use, while also allowing for higher applied voltages without electrolysis. This work aims to further the understanding of the dominant mechanisms of IPT actuation and how these are affected when an ionic liquid is used as solvent. A micromechanical model of IPT actuation is developed following a previous approach given by Nemat-Nasser, and the dominant relationships in actuation are demonstrated through an analysis of electrostatic cluster interactions. The elastic modulus of Nafion as a function of ionic liquid uptake is measured using uniaxial tension tests and modeled in a micromechanical framework, showing an excellent fit to the data. Charge transport is modeled by considering both the cation and anion of the ionic liquid as mobile charge carriers, a phenomenon which is unique to ionic liquid IPTs as compared to their water-based counterparts. Numerical simulations are performed using the finite element method, and a modified theory of ion transport is discussed which can be extended to accurately describe electrochemical migration of ionic liquid ions at higher applied voltages. The results presented here demonstrate the dominant mechanisms of IPT actuation and identify those unique to ionic liquid IPTs, giving directions for future research and transducer development.Master of Science
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Ballantyne, D. R. "Ionized accretion discs around black holes." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596325.
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Many galaxies in the Universe show evidence of a supermassive black hole at their dynamical centre. About 10-20% of these galaxies also contain an extremely bright, point-like continuum source in their nuclear region. These luminous objects are called active galactic nuclei (AGN), and are thought to be powered by material accreting onto the central black hole. The infalling gas loses its energy and angular momentum by passing through an accretion disc. The disc then radiates away this energy, and it is this radiation that is observed as an AGN. When observed in the X-ray waveband AGN are found to be very bright and rapidly variable (on timescales as small as 1000 s), implying that the emission must originate from the innermost regions of the central engine. X-ray spectra of AGN often exhibit distinct features that are attributed to radiation reflecting off of the accretion disc. Therefore, it is possible to use sensitive X-ray spectroscopic observations of AGN to directly probe the physics of accretion flows only a short distance away from the black hole. Comparing the results from AGN with different properties, such as luminosity or radio power, may allow general conclusions on the AGN phenomenon to be drawn. This thesis applies computations of X-ray reflection spectra to observations of different AGN in order to determine various properties of their accretion flows. The calculations take into account the ionization effects of the incident radiation and consider different density structures for the surface of the accretion disc. It was found that the model spectra were a good description of the observed X-ray data for many AGN between 1 and 10 keV. In particular, five narrow-line Seyfert 1 galaxies were well fit with reflection spectra from a highly ionized accretion disc, consistent with the idea that they contain rapidly accreting black holes. A similar result was found when fitting the data of 3C 120, a broad-line radio galaxy, which argues against the claim that radio-loud AGN have truncated accretion discs. On the other hand, a weakly ionized reflector proved to be a better fit to the Seyfert 1 galaxy MCG-6-30-15.
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Menzel, Raymond. "Multifluid magnetohydrodynamics of weakly ionized plasmas." Thesis, Rensselaer Polytechnic Institute, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3630022.
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The process of star formation is an integral part of the new field of astrobiology, which studies the origins of life. Since the gas that collapses to form stars and their resulting protoplanetary disks is known to be weakly ionized and contain magnetic fields, star formation is governed by multifluid magnetohydrodynamics. In this thesis we consider two important problems involved in the process of star formation that may have strongly affected the origins of life, with the goal of determining the thermal effects of these flows and modeling the physical conditions of these environments.
We first considered the outstanding problem of how primitive bodies, specifically asteroids, were heated in protoplanetary disks early in their lifetime. Reexamining asteroid heating due to the classic unipolar induction heating mechanism described by Sonett et al. (1970), we find that this mechanism contains a subtle conceptual error. As original conceived, heating due to this mechanism is driven by a uniform, supersonic, fully-ionized, magnetized, T Tauri solar wind, which sweeps past an asteroid and causes the asteroid to experience a motional electric field in its rest frame. We point out that this mechanism ignores the interaction between the body surface and the flow, and thus only correctly describes the electric field far away from the asteroid where the plasma streams freely. In a realistic protoplanetary disk environment, we show that the interaction due to friction between the asteroid surface and the flow causes a shear layer to form close to the body, wherein the motional electric field predicted by Sonett et al. decreases and tends to zero at the asteroid surface. We correct this error by using the equations of multifluid magnetohydrodynamics to explicitly treat the shear layer. We calculate the velocity field in the plasma, and the magnetic and electric fields everywhere for two flows over an idealized infinite asteroid with varying magnetic field orientations. We show that the total electric field in the asteroid may either be of comparable strength to the electric field predicted by Sonett et al. or vanish depending on the magnetic field geometry. We include the effects of dust grains in the gas and calculate the heating rates in the plasma flow due to ion-neutral scattering and viscous dissipation. We term this newly discovered heating mechanism “electrodynamic heating”, use measurements of asteroid electrical conductivities to estimate the upper limits of the possible heating rates and amount of thermal energy that can be deposited in the solid body, and compare these to the heating produced by the decay of radioactive nuclei like Al26.
For the second problem we modeled molecular line emission from time-dependent multifluid MHD shock waves in star-forming regions. By incorporating realistic radiative cooling by CO and H2 into the numerical method developed by Ciolek & Roberge (2013), we present the only current models of truly time-dependent multifluid MHD shock waves in weakly-ionized plasmas. Using the physical conditions determined by our models, we present predictions of molecular emission in the form of excitation diagrams, which can be compared to observations of protostellar outflows in order to trace the physical conditions of these environments. Current work focuses on creating models for varying initial conditions and shock ages, which are and will be the subject of several in progress studies of observed molecular outflows and will provide further insight into the physics and chemistry of these flows.
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Graham, H. K. "Ionized calcium in health and disease." Thesis, Queen's University Belfast, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233353.
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Tsamis, Ionnis. "Heavy element abundance in ionized nebulae." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270150.
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Fontana, Luis Cesar. "Nitretação ionica em aços baixo carbono." reponame:Repositório Institucional da UFSC, 1991. http://repositorio.ufsc.br/xmlui/handle/123456789/75728.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina. Centro de Ciencias Fisicas e MatematicasMade available in DSpace on 2012-10-16T03:54:08Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T17:02:19Z : No. of bitstreams: 1 84779.pdf: 2948983 bytes, checksum: 8da9aacf73797b7837e25f1547bd8ab8 (MD5)
Amostras de aço 1020 são nitretadas ionicamente num plasma de N2+ H2. São feitos estudos da evolução das camadas de nitretos em função da temperatura, do tempo de nitretação e da composição da mistura gasosa N2 + H2. No estudo da temperatura de nitretação, são nitretadas amostras durante três horas em temperaturas que variam de 400 a 600 °C . Este estudo é feito para duas composições da mistura gasosa: 80%N2 + 20%H2 e 20%N2 + 80%H2. No estudo sobre a influência do tempo de nitretação são nitretadas amostras com tempos entre 0.25h e 12.0h. Este estudo é realizado com uma única composição da mistura (80%N2 + 20%H2) e em duas temperaturas: 490 e 550°C . No estudo da mistura gasosa N2 + H2 são nitretadas amostras em 480°C durante uma hora, com misturas gasosas que variam entre 10 e 100% de N2. As camadas de nitretos formadas são analisadas por metalografia, difração de raios X e microdureza. É identificada a formação de uma camada branca de fase e -Fe2-3N e/ou g'-Fe4N . Pode haver também a formação de uma camada escura, sob a camada branca, identificada como uma mistura das fases g' e nitroferrita. A microdureza da camada branca é da ordem de 800 Vickers e a da camada escura é da ordem de 400 Vickers enquanto que a microdureza do aço 1020 não nitretado é de 200 Vickers. A espessura da camada branca, em função da temperatura de nitretação, passa por um máximo e depois decresce. Em função do tempo de nitretação, a camada branca também passa por um máximo de espessura e depois decresce, porém de maneira mais suave. A camada escura, que se forma sob a camada branca, tem um crescimento contínuo no início do processo de nitretação com tendência à saturação no final. Esta camada pode ser considerada como um estágio intermediário de decomposição da camada branca. Uma taxa de hidrogênio maior que 5%, na mistura N2 +H2, diminui a espessura da camada de nitretos e evita a formação da camada escura. A mistura de 95%N2 + 5%H2 apresenta os melhores resultados quanto a espessura e microdureza da camada de nitretos bem como da estabilidade do plasma.
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Eliah, Dawod Ibrahim. "Structural integrity of highly ionized peptides." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-387886.
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In order to understand the behaviour and function of proteins, their three dimensional structure needs to be known. Determination of macro-molecules’ structures is done using X-ray diffraction or electron microscopy, where the resulting diffraction pattern is used for molecular reconstruction. These methods are however limited by radiation damage.The aim of this work is to study radiation damage of peptides in proteins using computer simulations. Increased understanding of the atomic and molecular dynamics can contribute to an improvement of the method ofimaging biological molecules. To be able to describe the processes that take place as accurately as possible, the problem must treated quantum mechanically.Thus, the simulations are performed with molecular dynamics based on first principles. In order to capture the dynamics of the excited states of the molecule when exposed to X-rays, time-dependent density functional theory with delta self-consistent field is used. These simulations are compared to ground state simulations. The results of the thesis conclude that the excited and ground state simulations result in differences in the dynamics, which are most pronounced for lager molecules.
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Paladini, Roberta. "The Warm Ionized Gas Thin Layer." Doctoral thesis, SISSA, 2003. http://hdl.handle.net/20.500.11767/4309.
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Among the phases of the interstellar gas, the warm ionized is the least known. Its spatial
distribution is characterized by a thin and a thick layer where the former corresponds
to the ionized gas in the proximity of the plane and the latter to the gas which is found
at larger distances from the plane. The thin layer comprises discrete HII regions and
diffuse gas. Despite the important role assigned to the thin layer by current theoretical
models, so far our knowledge of it has been based either on oversimplified analytical
calculations or on the scattered observational information coming from pulsar dispersion
and scattering measures which largely suffer from undersampling.
In this Thesis, after an overview of the current knowledge of the Galactic interstellar
medium and of its constituents, and particularly of the warm ionized medium, we focus
on our main goal which is to contribute to build a realistic picture of the thin layer
by exploiting the information widely spread in the literature. This work has proceeded
along two main lines: the systematic investigation of the thin-layer source-component,
i.e. HII regions, and the study of the interplay between this source-component and the
diffuse gas.
Collecting radio data on Galactic HII regions from 24 published works, we have built
a self-consistent data base comprising 1442 sources. This work has resulted in the construction
of a Master Catalog (which consists in 11 sub-catalogs storing the original
information from the source references) and of a Synthetic Catalog (which is a readily
accessible version of the Master Catalog at 2. 7 GHz). This represents the most extensive
list of compact HII regions to date. We have then exploited this data-base to investigate
the distribution of the warm ionized gas, as well as for applications in the field of Cosmic
Microwave Background studies (calibration, beam-shape and pointing reconstruction,
stray light, understanding of the Galactic foregrounds).
The kinematic information contained in the catalog has allowed us to study the spatial
distribution of 550 objects taken from the Synthetic Catalog. For each source, a
galactocentric distance has been derived using the Fich et al. [106] rotation model. vVe
have found a highly significant correlation between luminosities and linear diameters,
which was exploited to resolve the solar-distance degeneracy. vVe have then been able
to estimate the scale height of the HII region distribution. Within the solar circle, we
have obtained an azimuthally-averaged thickness, Omega_z around 52 pc which is comparable to the
estimated scale height of the OB star distribution but narrower than that of the diffuse HII and HI. The analysis of the z-clistribution has retrieved other important results: a
confirmation of the presence of the warp; evidence of an increasing width of the distribution
as a function of the galactocentric radius; a confirmation of the electron temperature
gradient with galactocentric radius; a spiral-like structure in agreement with the model
by Taylor & Cordes [311].
The relationship between HII regions and the diffuse gas in the thin layer has been
addressed by considering data at 408 MHz (Haslam et al. [150]) and at 5 GHz (Haynes
et al. [151]) for the region of the Galactic Plane in the coordinate range 20° < l < 30°,
-1.5° < b < +1.5°. After adjusting the zero levels of the two surveys, we have applied
a component separation technique to the observed radio continuum by exploiting the
spectral dependence of the two kinds of emissions which overlap at these frequencies,
namely free-free and synchrotron radiation. The synchrotron spectral index has been
kept fixed during this phase of the analysis. The distribution of spectral indices for the
total Galactic emission has been recovered across the considered region. Evidence of a
flattening of the spectral index in proximity of the plane has been found. This has been
interpreted as the effect of intense thermal emission due to HII regions. A comparison
between the latitude distribution of the free-free and that of the HII regions located in
this coordinate range has shown clearly the presence of diffuse gas in the thin layer. A
preliminary estimate of the contribution of HII regions to the total emission budget has
yielded a value of order of 11 % which, again, supports the hypothesis of a dominant role
of the diffuse ionized gas in the thin layer.
Finally, we want to point out that the analysis we have described has relied on radio data
which, so far, have found limited applications in this context. The continuum free-free
emission has long been considered (as in the case of experiments dedicated to the Cosmic
Microwave Radiation) as a source of disturbance, rather than a source of information
or, in other words, as a foreground to remove. This is mostly due to the fact that
this emission is partly masked by intense synchrotron radiation produced by relativistic
electrons accelerated in the Galactic magnetic field. However such data, when properly
handled, have the unique advantage with respect to other tracers of providing access to
the distribution of Galactic warm ionized gas without suffering from undersampling or
extinction. The same advantages also characterize radio recombination lines. So far, due
to the limited instrumental capabilities, it was not possible to exploit fully the wealth of
information contained in these data. Yet, the next generation of experiments will open
up a new window on the warm ionized gas, allowing its systematic, unbiased exploration
throughout the Galaxy.
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Nogueira, Viviane Carvalho. "Otimização do eletrolito polimerico baseado no complexo poli (epicloridrina-co-oxido de etileno) com NaI/I2 para celulas solares de TiO2/corante." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248662.
Full textAbstract:
Orientadores: Marco-Aurelio De Paoli, Claudia LongoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-04T15:23:29Z (GMT). No. of bitstreams: 1 Nogueira_VivianeCarvalho_M.pdf: 7956042 bytes, checksum: 3497431ee35a85b9d6ad28d95b6055c0 (MD5) Previous issue date: 2005
Resumo: As células solares de TiO2 sensibilizadas por corante, DSSC, são constituídas por um filme nanoporoso de TiO2 modificado por um corante fotosensibilizador, um eletrólito no qual está presente o par redox I¨/I3¨, e um contra-eletrodo de platina. Desde 1996 o Laboratório de Polímeros Condutores e Reciclagem (LPCR) do Instituto de Química da Unicamp vem se dedicando ao desenvolvimento de células solares de TiO2/corante de estado sólido, através do emprego de eletrólitos poliméricos. A substituição do eletrólito líquido por um eletrólito polimérico visa minimizar os problemas decorrentes de vazamento ou evaporação do solvente, além de facilitar a montagem dos dispositivos. Estudos anteriores mostraram que as DSSC com eletrólito polimérico apresentam uma baixa estabilidade. Como a durabilidade de um dispositivo é um fator fundamental visando sua produção e uso em larga escala, o objetivo desta dissertação foi investigar as possíveis causas da baixa estabilidade das DSSC e otimizar a composição do eletrólito polimérico baseado em poli(epicloridrina-co-óxido de etileno), P(EO-EPI)84:16, NaI e l2, visando obter células solares com maior eficiência e estabilidade. Os resultados obtidos mostraram que a baixa estabilidade destas células está relacionada com a elevada quantidade de solvente residual presente no dispositivo após o término de sua montagem. A primeira parte do trabalho consistiu em eliminar esta interferência. O eletrólito polimérico foi otimizado através da adição do plastificante poli(etileno glicol) metil éter, P(EGME), que levou a uma redução significativa da temperatura de transição vítrea (Tg) do material polimérico, aumentando a flexibilidade das cadeias poliméricas e também participando na coordenação dos cátions Na, levando ao aumento da condutividade do eletrólito polimérico (s = 1,7 x 10 S cm, para 13 % m/m NaI). O coeficiente de difusão estimado para os íons no eletrólito polimérico com plastificante foi de 2 x 10 cms, aproximadamente 5 vezes maior do que para o eletrólito sem plastificante. A adição do plastificante não comprometeu as estabilidades térmicas, eletroquímicas e dimensionais dos filmes de eletrólito polimérico. A DSSC preparada com o eletrólito de P(EO-EPI) : P(EGME) (1:1) e 13 % (m/m) de NaI/I2 apresentou uma corrente de curto-circuito (ISC) de 1,88 mA cm e eficiência de conversão de energia (h) de 0,52 % (100 mW cm). Sob 10 mW cm, ISC = 0,60 mA cm e h = 1,75 %. Estes resultados mostram que a adição do plastificante contribuiu para melhorar o desempenho da célula solar e o estudo de estabilidade desta DSSC mostrou uma redução de menos de 15 % na eficiência de conversão de energia após 30 dias de irradiação.
Abstract: Dye sensitized solar cells, DSSC, consist of a nanoporous TiO2 electrode modified by a Ru-complex dye, an electrolyte containing the redox couple I¨/I3¨and a Pt counter electrode. Since 1996 the Conductive Polymers and Recycling Laboratory (LPCR) of the Chemistry Institute at Unicamp is developing solid state dye sensitized solar cells through the use of polymer electrolytes. The substitution of the liquid electrolyte by a polymeric one, eliminates the need of perfect sealing and avoids many problems caused by leakage or evaporation of the solvent, besides making the assembly of the cells much easier. Previous works showed that the DSSC assembled with polymer electrolytes present a poor stability. The durability of a device is a very important parameter when considering practical interests for application of DSSC, so the aim of this dissertation was to investigate the major causes of the poor stability ofthe DSSC and to optimize the composition of the polymer electrolyte based on poly(epichlorohydrin-co-ethylene oxide), P(EO-EPI)84:16, NaI and I2, in order to obtain solar cells with improved efficiency and stability. The results showed that the poor stability of the solar cells could be assigned to the presence of a large amounts of residual solvent in the assembled devices. The first step of the work consisted in eliminating this interference. The polymer electrolyte was optimized through the addition of the plasticizer, poly(ethylene glycol methyl ether), P(EGME), leading to a significant reduction of the copolymer glass transition temperature (Tg), increasing the chains flexibility, and also coordinating the Nacations, enhancing the ionic conductivity of the polymer electrolyte (s = 1.7 X 10 S cm, with 13 wt. % NaI). The diffusion coefficient estimated for the polymer electrolyte with the plasticizer was 2 x 10 cm s, about 5 times larger than for the electrolyte without plasticizer. The plasticizer did not affeet the thermal, electrochemical and dimensional stabilities of the polymer electrolyte films. The DSSC assembled with the polymer electrolyte based on P(EO-EPI) : P(EGME) (1:1) and 13 wt. % of NaI/I2 showed short circuit current (ISC) of 1.88 mA cm and overall conversion efficiency (h) of 0.52 % (100 mW cm). At 10 mW cm, ISC = 0.60 mA cm and h = 1.75 %. These results show that the plasticizer enhanced the performance of the solar cell. The stability test showed a reduction of less than 15 % in the efficiency of energy conversion after irradiating the DSSC for 30 days.
Mestrado
Quimica Inorganica
Mestre em Química
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Arsenikos, Stavros. "Tectonic evolution and structure of the Cyrenaica margin, Libya (East Mediterranean )." Thesis, Cergy-Pontoise, 2014. http://www.theses.fr/2014CERG0741.
Full textAbstract:
En Méditerranée orientale, la paleo-marge sud de la Téthys a subit des épisodes polyphasés d'extension pendant le Paléozoïque et le Mésozoïque. Cette marge a été postérieurement inversée pendant des épisodes compressifs et discontinus depuis le Crétacé supérieur liés à la convergence entre l'Afrique et l'Eurasie.La marge Cyrénaïque (nord-est Libye) a enregistré ces épisodes extensifs et compressifs. Elle permet donc l'analyse des inversions et de leurs relations avec les évènements ayant eu lieu le long de la frontière de la plaque Africaine (i.e. subduction Hellenique).Le bassin de Sirte, adjacent à la Cyrénaïque montre une direction oblique, ne présente pas la même déformation et est caractérisé par une subsidence continue depuis le Mésozoïque.Des données de sismique (réflexion) combinées à des rapports et des corrélations de puits, nous ont permis d'examiner et de discuter les interactions entre la Cyrénaïque, le bassin de Sirte et les domaines profonds (i.e. bassin Ionien).Ce travail permet de mieux préciser les différents épisodes d'extension, de contraindre les évènements compressifs enregistrés par la région Cyrénaïque, d'observer les structures du bassin de Sirte et de clarifier en partie son évolution.Finalement cette partie de la marge est intégrée dans le cadre géodynamique régional de la Téthys sud et permet de discuter l'âge ainsi que le mécanisme d'ouverture pour la branche orientale de la MéditerranéeIn the Eastern Mediterranean, the South-Tethys paleo-margin experienced poly-phased rifting episodes during Paleozoic and Mesozoic times. This margin has been subsequently inverted by discontinuous events occurring since the Late Cretaceous as a consequence of the Africa-Eurasia convergence.The Cyrenaica margin (northeast Libya) has recorded these extensional and compressional events. It thus gives the opportunity to analyse these inversion and their possible causal links with events occurring along the plate boundary (i.e. within the Hellenic subduction).The adjacent Sirt Basin, follows an oblique direction, did not suffer the same deformation as Cyrenaica and has recorded a continuous subsidence since the Mesozoic.Offshore seismic data combined with well correlations have permitted us to investigate and discuss the interactions between Cyrenaica, Sirt Basin and the deeper domains (i.e. Ionian Basin).We were able to document the different rift episodes, better constrain the compressional events on Cyrenaica, observe characteristics of the architecture of the Sirt Basin and clarify part of its evolution.Finally we integrate this part of the margin, in the regional geodynamic frame of the East Mediterranean branch of the Neo-Tethys by discussing the timing and mechanism which led to its opening
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Kumar, Parveen, Ashok Kumar Shukla, and Subramanian Yashonath. "Relationship between ionic radius and pressure dependence of ionic conductivity in water." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-193244.
Full textAbstract:
Experimental measurements of ionic conductivity in water are analysed in order to obtain insight into the pressure dependence of limiting ionic conductivity of individual ions (λ0) for ions of differing sizes. Conductivities of individual ions, λ0 do not exhibit the same trend as a function of pressure for all ions. Our analysis suggests that the effect of pressure on ionic conductivity depends on the temperature. At low temperatures, the effect of pressure on relatively small ions such as Li+ exhibit an increase in conductivity with pressure. Intermediate sized ions exhibit an increase in conductivity with increase in pressure initially and then at still higher pressures, a decrease in ionic conductivity is observed. Although there are data at low temperatures for ions of large radius, the effect of increased pressure is expected to lower conductivity with increase in pressure over the whole range. At higher temperatures, the
dependence of conductivity on pressure changes and these changes are discussed. Divalent ions such as SO2−4 exhibit different trends as a function of pressure at different temperatures. Both the divalent ions (Ca2+ and SO2−4 ) for which experimental data exists, exhibit an increase with pressure at lower temperatures. At slightly higher temperatures, a maximum in conductivity is seen as a function of pressure over the same range of pressure.
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Kumar, Parveen, Ashok Kumar Shukla, and Subramanian Yashonath. "Relationship between ionic radius and pressure dependence of ionic conductivity in water." Diffusion fundamentals 6 (2007) 8, S. 1-14, 2007. https://ul.qucosa.de/id/qucosa%3A14182.
Full textAbstract:
Experimental measurements of ionic conductivity in water are analysed in order to obtain insight into the pressure dependence of limiting ionic conductivity of individual ions (λ0) for ions of differing sizes. Conductivities of individual ions, λ0 do not exhibit the same trend as a function of pressure for all ions. Our analysis suggests that the effect of pressure on ionic conductivity depends on the temperature. At low temperatures, the effect of pressure on relatively small ions such as Li+ exhibit an increase in conductivity with pressure. Intermediate sized ions exhibit an increase in conductivity with increase in pressure initially and then at still higher pressures, a decrease in ionic conductivity is observed. Although there are data at low temperatures for ions of large radius, the effect of increased pressure is expected to lower conductivity with increase in pressure over the whole range. At higher temperatures, the
dependence of conductivity on pressure changes and these changes are discussed. Divalent ions such as SO2−4 exhibit different trends as a function of pressure at different temperatures. Both the divalent ions (Ca2+ and SO2−4 ) for which experimental data exists, exhibit an increase with pressure at lower temperatures. At slightly higher temperatures, a maximum in conductivity is seen as a function of pressure over the same range of pressure.
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Mudarri, Timothy C. "A Novel Use for Ionic Polymer Transducers for Ionic Sensing in Liquid." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9671.
Full textAbstract:
Ionic electroactive polymers have been developed as mechanical sensors or actuators, taking advantage of the electromechanical coupling of the materials. This research attempts to take advantage of the chemomechanical and chemoelectrical coupling by characterizing the transient response as the polymer undergoes an ion exchange, thus using the polymer for ionic sensing. Nafionâ ¢ is a biocompatible material, and an implantable polymeric ion sensor which has applications in the biomedical field for bone healing research. An ion sensor and a strain gauge could determine the effects of motion allowed at the fracture site, thus improving rehabilitation procedures for bone fractures.
The charge sensitivity of the material and the capacitance of the material were analyzed to determine the transient response. Both measures indicate a change when immersed in ionic salt solutions. It is demonstrated that measuring the capacitance is the best indicator of an ion exchange. Relative to a flat response in deionized water (±2%), the capacitance of the polymer exhibits an exponential decay of ~25% of its peak when placed in a salt solution. A linear correlation between the time constant of the decay and the ionic size of the exchanging ion was developed that could reasonably predict a diffusing ion. Tests using an energy dispersive spectrometer (EDS) indicate that 90% of the exchange occurs in the first 20 minutes, shown by both capacitance decay and an atomic level scan. The diffusion rate time constant was found to within 0.3% of the capacitance time constant, confirming the ability of capacitance to measure ion exchange.Master of Science
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Guggilla, Srinivas. "Synthesis and characterization of Perovskite-related ionic and mixed ionic-electronic conductors /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Eren, Kenan. "Les sanctuaires et l'espace de l'Ionie à l'époque archaïque." Paris 1, 2009. http://www.theses.fr/2009PA010557.
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Il est difficile d'établir pour l'Ionie, surtout pour le VIle siècle, un territoire avec des frontières définies et avec des cités structurées. En conséquence, I'étude de la répartition des sanctuaires dans un espace ionien moins structuré ne nous permet pas d'établir une différenciation nette entre urbain et extra-urbain. En revanche, la géographie humaine apparaît comme I'acteur principal de la création des cultes et la relation des sanctuaires avec la mer, les habitats et les routes de communication reste toujours le facteur Ie plus important pour le choix de localisation. Ainsi, au cours du VIle siècle, I'appartenance a des réseaux internationaux à travers la communication maritime détermine les principales séries d'offrandes. En revanche, vers la fin de I'époque archaïque, I'espace des cités ioniennes se définissent plus précisément en relation à leurs différents composants déjà en place, et les productions locales constituent la majorité des offrandes.
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Crowhurst, Lorna. "Acidity in ionic liquids." Thesis, Imperial College London, 2006. http://hdl.handle.net/10044/1/11301.
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Johnson, Kristien Paul. "Variability of ionic magnesium." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60850.pdf.
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Anderson, K. "Hydrogenations in ionic liquids." Thesis, Queen's University Belfast, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411762.
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Fröhlich, U. "Chirality and ionic liquids." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426700.
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Fitzgerald, A. M. "Electrochemistry in ionic liquids." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419511.
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Brooks, C. B. "Electrochemistry in ionic liquids." Thesis, Queen's University Belfast, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401797.
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De, La Osa Maria Jose Torres. "Characterization of ionic liquids." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342984.
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Driver, Gordon William. "Thermodynamics of ionic liquids." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479423.
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Sangoro, Joshua, Ciprian Iacob, Rustem Valiullin, Jörg Kärger, and Friedrich Kremer. "Diffusion in ionic liquids." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-185598.
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Foreiter, M. B. "Novel chiral ionic liquids." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675450.
Full textAbstract:
Chiral ionic liquids have been present in the literature for more than a decade. The development of original chiral systems of ions is currently far more difficult than ever before. The path of innovation in this topic, however, should not be focussed exclusively on the introduction of chirality into the ionic liquid structure, but should go beyond, towards further functionalisation of these species. The combination of chirality and a functional moiety has been the starting point for the present work. Here, a focus was on creation of chiral ionic liquids possessing distinct functional groups: a strong hydrogen-bonding thiourea group was selected. Consequently, a series of novel chiral thiouronium salts were synthesised. The chirality was sourced in cheap, but structurally robust, chiral amines: (S)-1- phenylethylamine and (+)-dehydroabietylamine. Because the thiourea moiety can be functionalised at five different sites, a wide range of thiouronium and thiourea-functionalised ionic liquids could be prepared and analysed, and the influence coming from their structural diversity explored. The crucial point for the project was a confirmation of rotameric behaviour in these new thiouronium systems. Here, the hindered rotation has been examined by NMR spectroscopy, and compared with literature findings. The key message concludes that, in the thiouronium system, the C-S rotation predominates when placed in a highly polar solvent; then the syn syn conformation dominates. When, on the other hand, the constraints of the surroundings are eliminated, the syn-anti form is energetically preferable. Here, the rotamerism of the thiouronium cation in a neat liquid form was examined for the first time. Finally, these novel chiral compounds have found applications based on molecular recognition by the thiourea moiety. The discrimination of chiral oxoanions by these salts using NMR spectroscopy has been successful. A strong, double hydrogen-bonded connection between the chiral thiouronium moiety and the oxoanion proved to be a key point, generating results a competitive with the literature results. Following this approach, the separation capabilities of thiouronium systems were also explored, given that they can be effective agents for oxoanion extractions. This work demonstrated that a careful design of functional molecules is scientifically significant, and can have a great impact on their applications.
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Hall, L. S. I. "Supported ionic liquid catalysis." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676492.
Full textAbstract:
Over the last few years interest in supported ionic liquid (IL) catalysis has been growing. This is due to the increased selectivity and catalytic activity obtained in IL based systems compared with molecular solvents coupled with the advantages of solid catalyst in terms of separation. In this thesis, the effect of supported ionic liquid catalysis will be examined for various different reactions including the hydrogenation of citral and cinnamaldehyde, the Diels-Alder, Mukaiyama aldol and carbonyl-ene reactions. Solid catalyst ionic liquid layers (SCILL) catalysts and Ionic polymers (IP) were used for the hydrogenation of citral and cinnamaldehyde. Overall a Pd/Ab03 with and without an IL produced significantly higher selectivities and conversions compared with a Pd/C catalyst. The IP catalysts were shown to greatly increase the selectivity. The IP synthesised from the commercial Amberlite 910, produced the best results for both substrates achieving high selectivities up to 99%.
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Niedermeyer, Heiko Jannes. "Mixtures of ionic liquids." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/11645.
Full textAbstract:
Ionic liquids have gained a reputation as ‘designer solvents’ due to the wide range of properties that are accessible and the fine degree of ‘tuning’ allowed by varying the constituting ions. To further widen the parameter space, yet allow the prediction of properties, mixtures of ionic liquids are analysed in this project. An extensive literature review is performed, covering the full range of available publications on this subject at the time of writing. The available literature is extended by original research on mixtures covering a range of structurally different anions and cations that have not been reported in mixtures before. Chemical and physical properties such as conductivity, viscosity, density and solvent properties are evaluated. The physical properties are found to behave largely ideally with few exceptions, while the solvent properties of mixtures are found to behave in a systematic manner according to simple equilibrium laws. A potential explanation for the dependence of the H-bond acidity of ionic liquid cations on the basicity of the corresponding anion based on multiple available acidic protons of the cation is discussed and evaluated. Computational methods to predict the acidity and basicity parameters α and β of pure ionic liquids are developed and evaluated. For the H-bond acidity α the electrostatic potential, complex formation with NCH and electronic excitations of the complex with Reichardt’s Dye are found successful. For β, properties of the complex with HF are found to correlate well with the H-bond basicity. The properties of a siloxane substituted cation are analysed by DFT calculations to explain the low viscosity of the corresponding ionic liquids. The cation is found to form intramolecular interactions and have lowered barriers for the movement of the substituent, thus minimising cation–cation interactions, increasing entropy and facilitating the movement of anions.
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Engel, Brian Scott. "Studies in ionic liquids." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501259.
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MAIS, LAURA. "Electrodeposition of Nb, Ta, Zr and Cu from Ionic Liquid for Nanocomposites Preparation." Doctoral thesis, Università degli Studi di Cagliari, 2015. http://hdl.handle.net/11584/266571.
Full textAbstract:
Multilayer metal materials with nanometric scale are important in modern engineering applications. Composite materials based on metals with different characteristics give rise to new materials with unique properties. Among the others, nanostructured composites constituted by immiscible metals can present interfaces able to control defects produced by high doses of radiation, stress and temperature: their properties can be exploited in nuclear power reactor. Immiscible systems constituted by Cu/Nb or Cu/Ta multilayers exhibit higher thermal stability and improved mechanical properties with respect to bulk Nb, bulk Ta and bulk Cu. Refractory metals present high melting point, high hardness and high resistance against strong acids and bases. The electrodeposition of these metals presents several limitations: the most important is the very negative deposition potential that makes difficult the deposition of metals such as niobium, tantalum and zirconium. Since both oxygen reduction and hydrogen evolution from water splitting occur at potential values much less cathodic than the metals reduction, at the low potential requested to obtain niobium, tantalum and zirconium in metal form it is necessary the use of electrolytes free of water and oxygen and characterized by high stability in large potential windows. To overcome this limitation, the electrodeposition from molten salts or ionic liquids as solvents have been proposed.
In the present project the electrochemical coating of niobium, tantalum zirconium and copper has been investigated in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide([BMP][TFSA]) on both boron doped diamond (BDD) and metal substrates in order to determine the reduction path for both single metal and nanometric composites electrodeposition.
Electrochemical experiments have been performed at different temperatures in a glove box, under nitrogen atmosphere. Galvanostatic runs and cyclic voltammograms performed at different scan rates and different potential windows have been carried out in order to determine the behaviour of the systems employed. Potentiostatic experiments were performed at the potential values corresponding to the voltammetric peaks and the samples obtained were analysed by SEM-EDX analyses.
Regarding the electrodeposition of refractory metals nanometric crystallites have been obtained at 125 °C.
Cu/Nb and Cu/Ta composites have been prepared by a dual bath deposition technique; the deposits were constituted by fine crystallites with average sizes in the range 50-100 nm. The elemental maps indicate a different distribution of Cu/Nb and Cu/Ta in the composites obtained with the different substrates.