Made available in DSpace on 2014-12-17T14:09:14Z (GMT). No. of bitstreams: 1 AnaADP_TESE.pdf: 2810011 bytes, checksum: 6f11363dfc6e540fe688b7737b77893b (MD5) Previous issue date: 2012-11-04 / Aiming to reduce and reuse waste oil from oily sludge generated in large volumes by the oil industry, types of nanostructured materials Al-MCM-41 and Al-SBA-15, with ratios of Si / Al = 50, were synthesized , and calcined solids used as catalysts in the degradation of oily sludge thermocatalytic oil from oilfield Canto do Amaro, in the state of Rio Grande do Norte. Samples of nanostructured materials were characterized by thermogravimetric analysis (TG / DTG), X-ray diffraction (XRD), scanning electron microscopy (SEM), absorption spectroscopy in the infrared Fourier transform (FT-IR) and adsorption nitrogen (BET). The characterization showed that the synthesized materials resulted in a catalyst nanostructure, and ordered pore diameter and surface area according to existing literature. The oily sludge sample was characterized by determining the API gravity and sulfur content and SARA analysis (saturates, aromatics, resins and asphaltenes). The results showed a material equivalent to the average oil with API gravity of 26.1, a low sulfur content and considerable amount of resins and asphaltenes, presented above in the literature. The thermal and catalytic degradation of the oily sludge oil was performed from room temperature to 870 ? C in the ratios of heating of 5, 10 and 20 ? C min-1. The curves generated by TG / DTG showed a more accelerated degradation of oily sludge when it introduced the nanostructured materials. These results were confirmed by activation energy calculated by the method of Flynn-Wall, in the presence of catalysts reduced energy, in particular in the range of cracking, showing the process efficiency, mainly for extraction of lightweight materials of composition of oily sludge, such as diesel and gasoline / Com o objetivo de reduzir e reutilizar o res?duo de borra oleosa de petr?leo, gerado em grandes volumes pela ind?stria petrol?fera, materiais nanoestruturados dos tipos Al-MCM-41 e Al-SBA-15, com raz?es de Si/Al = 50, foram sintetizados, calcinados e utilizados como s?lidos catal?ticos na degrada??o termocatal?tica da borra oleosa de petr?leo, proveniente do campo petrol?fero Canto do Amaro, no estado do Rio Grande do Norte. As amostras dos materiais nanoestruturados foram caracterizadas por an?lise termogravim?trica (TG/DTG), difra??o de raios X (DRX), microscopia eletr?nica de varredura (MEV), espectroscopia de absor??o na regi?o do infravermelho com transformada de Fourier (FT-IR) e adsor??o de nitrog?nio (BET). A caracteriza??o mostrou que os materiais sintetizados resultaram em um catalisador nanoestruturado, ordenado e com di?metro de poros e ?rea superficial de acordo com a literatura existente. A amostra de borra oleosa foi caracterizada atrav?s da determina??o do grau API e do teor de enxofre e da an?lise do SARA (saturados, arom?ticos, resinas e asfaltenos). Os resultados mostraram um material equivalente ao petr?leo m?dio, com grau API de 26,1, baixo teor de enxofre e com quantidade consider?vel de resinas e asfaltenos, acima da apresentada na literatura. A degrada??o t?rmica e catal?tica da borra oleosa de petr?leo foi realizada da temperatura ambiente at? 870?C, nas raz?es de aquecimento de 5, 10 e 20oC min-1. As curvas geradas pela TG/DTG apresentaram uma degrada??o mais acelerada da borra oleosa quando se introduziram os materiais nanoestruturados. Esses resultados foram ratificados pela energia de ativa??o, calculada atrav?s do m?todo de Flynn-Wall, em que a presen?a dos catalisadores reduziu a energia, em especial na faixa de craqueamento, mostrando a efici?ncia do processo, principalmente para a extra??o de materiais leves da composi??o da borra oleosa, como diesel e gasolina

This study sought to enrich the research in cross-border strategic brand alliance (SBA), an international business practice highly utilized today. In order to spread out the risk of competing in international markets, firms formed alliances with overseas counterparts. However, confusing positioning and inaccuracies in communication in cross-cultural settings reduced the success rate of these partnerships. The content analysis examined cross-border SBA advertisements to shed light on their communicational strategies. Taiwan and the US, representative of inherent cultural values in Eastern and Western countries, served as great research subjects for this comparative study. The findings suggested that cross-border SBA advertisements do not have significantly distinctive communication strategies except for the inherent difference in multi-national characteristics. However, cross-border SBA advertisements in both countries differ from generic advertisements documented in previous studies in terms of information cues, advertising appeals, and general communication strategies. The comparison between cross-border SBA advertisements was reflective of the cultural differences in these cultural contexts. In sum, cross-border SBA advertisements were embedded with stronger cultural distinctiveness and in need of special execution to integrate proper messages. / text

L’électrofilage est actuellement la méthode la plus utilisée pour la production de nanofibres grâce à sa simplicité, sa reproductibilité et la possibilité d’être industrialisée. Grâce à leurs propriétés particulières telles qu’un grand rapport surface-volume, une porosité inter-fibre élevée et une grande capacité d’adsorption, les nanofibres électrofilées sont de bons candidats pour de nombreuses applications telles que la filtration, les masques respiratoires, les matériaux composites, etc. Cependant, certaines applications particulières, telles que les capteurs, les systèmes d'administration contrôlée de médicaments ou les super condensateurs, exigent que les nanofibres doivent présenter des propriétés complémentaires telles que la conductivité électrique, la porosité de surface de nanofibres, l’hydrophobicité, ou d’autres propriétés particulières. Certains nanomatériaux comme les nanotubes de carbone, la silice mésoporeuse ordonnée, les argiles, ont des propriétés particulières comme la conductivité électriques élevée des nanotubes de carbone, la porosité des matériaux de silice mésoporeuse ordonnée ou de l’argile. Ces propriétés des nanomatériaux peuvent être les fonctions complémentaires cherchées. Dans notre étude, des non-tissés composés de nanofibres de polyacrylonitrile chargées par nanotubes de carbone à multi-parois (MWNT), de la montmorillonite sodique (MMT-Na) ou de la silice mésoporeuse ordonnée (de type SBA-15), sont produits par électrofilage. Les résultats montrent que l’insertion de MWNT rend le non-tissé conducteur en augmentant la conductivité électrique volumique par six ordres de grandeur (de ~ 2×10-12 à ~ 3×10-6 S/m) avec un très faible seuil de percolation de 0.5 % massique. Lorsque le non-tissé est soumis à une compression, la conductivité électrique volumique augmente en augmentant la pression (jusqu’à ~ 2 kPa). Ces non-tissés conducteurs sont très intéressants pour le développement des capteurs à faible amplitude. Les résultats montrent aussi que l’accessibilité des pores des particules inorganiques (c’est-à-dire, les mésopores de SBA-15 et l’espace interfoliaire de MMT-Na) insérées dans la structure nano fibreuse est encore possible. Il a été trouvé que plus de 50% des mésopores de SBA-15 insérées sont encore accessibles quelles que soit les conditions de l’électrofilage et la fraction massique de SBA-15. En outre, l’insertion de ces particules inorganiques apporte plus de stabilité thermique aux nanofibres composites. / Electrospinning is the most common method for the production of nanofibres due to its simplicity, repeatability, and the ability to be scaled up. Owing to their advanced properties like the high surface-to-volume ratio, high interfibrous porosity, high adsorption capacity, etc. electrospun nanofibers are good candidates for many applications such as filtration, respiratory masks, composite materials and others. However, some specific applications including sensors, controlled drug delivery systems, supercapacitors, etc. still require complimentary functions that do not exist in pristine nanofibers in their basic structure like the electrical conductivity, surface porosity of the nanofibers, hydrophobicity, and others.Nanomaterials like carbon nanotubes, ordered mesoporous silica, layered silicate, etc. are characterized by particular properties like the high electrical conductivity of carbon nanotubes, the porosity of ordered mesoporous silica or layered silicate. These particular properties of nanomaterials can fulfill of the targeted functions.In our study, nonwovens made from nanofibers of polyacrylonitrile incorporated with multiwalled carbon nanotubes (MWNT), layered silicate type Na-montmorillonite (Na-MMT) or ordered mesoporous silica type SBA-15 are successfully produced by electrospinning.Results reveal that the incorporation of MWNT altered the electrical state of the nonwoven from insolent to conductor where the volume electrical conductivity increased by six order of magnitude (from ~ 2×10-12 to ~ 3×10-6 S/m) with a very low percolation threshold of about 0.5 wt%. The application of mechanical pressure to the conductive nonwoven causes an increase in the volume electrical conductivity with the increase of the applied pressure (up to ~ 2 kPa). Such conductive nonwoven is very interesting for the development of sensor with low amplitude.Results also show that accessibility of the pores of the inorganic particles (i.e. mesopores of SBA-15 and interlayer space of Na-MMT) incorporated into the nanofibers is still possible. It is found that at least 50% of SBA-15 mesopores are still accessible whatever is the electrospinning conditions and SBA-15 mass fraction. In addition, the incorporation of the studied inorganic particles yields higher thermal stability for the composite nanofibers.

Cette étude porte sur la synthèse et la caractérisation d'oxydes de titane à grandes surfaces spécifiques et avec des tailles de pores dans le domaine des mésopores. Après une analyse critique de la bibliographie, nous avons choisi différentes voies de synthèse en vue de structurer l'oxyde de titane. L'obtention d'une mésoporosité a été faite par : utilisation d'agents structurants de type tensioactif cationique et non-ionique, par voie sol-gel en présence de porogène et par recouvrement de MTS siliciques mésoporeux par une monocouche de TiO2. Des oxydes de titane de 200 à 400 m²/g de surface spécifique et de taille de pores de 60 à 140 Å ont été obtenus. Ils ont ensuite été fonctionnalisés par des acides phosphoniques comportant soit des fonctions basiques (guanidine) soit des fonctions hydrophobes (chaîne alkyle C8). Les matériaux hybrides ainsi obtenus pourront être utilisés pour faire de la catalyse basique hétérogène.

The results of this study show that novel mesoporous carbons were obtained as inverse replica of SBA-15, HMS and MCM-41 silica templates, with a large pore diameter (2-4 nm), a BET surface area of 1867, 874 and 910 m2g –1 respectively for CA_SBA-15_LPG_105, CA_HMS_LPG_80 and CA_MCM- 41_LPG_80 with bimodal pore size distribution (PSD) in the mesopores range. The results obtained show that mesoporous carbon with graphitic structures can be synthesized via the LPG route.

Ce travail de thèse a pour but la synthèse de solides constitués de nanoparticules d'oxyde de fer de taille contrôlée, dispersées et en interaction forte avec des supports mésoporeux. L'originalité du travail consiste en un choix judicieux de précurseurs de fer : des complexes de type chélate. Via une dégradation thermique contrôlée, ils libèrent la phase active sous forme d'oxyde et la déposent sur les parois internes à forte courbure de la silice SBA-15 avec un degré de dispersion optimal. Ce phénomène de confinement, désigné "effet de panier", conduit après calcination à des particules de Fe2O3, dont la taille est régie par la géométrie des chélates. Dans le cas des composites Fe/Al2O3, le fer est très dispersé (plages d'oxyde mixte (Fe,Al)2O3) et fortement stabilisé grâce à une bonne interaction acide-base avec le support. Ces composites sont d'excellents catalyseurs pour l'oxydation du phénol par H2O2 en milieu aqueux, puisque l'élution de l'espèce active est très limitée (<2%).

The results of this study show that novel mesoporous carbons were obtained as inverse replica of SBA-15, HMS and MCM-41 silica templates, with a large pore diameter (2-4 nm), a BET surface area of 1867, 874 and 910 m2g –1 respectively for CA_SBA-15_LPG_105, CA_HMS_LPG_80 and CA_MCM- 41_LPG_80 with bimodal pore size distribution (PSD) in the mesopores range. The results obtained show that mesoporous carbon with graphitic structures can be synthesized via the LPG route.

Philosophiae Doctor - PhD / The results of this study show that novel mesoporous carbons were obtained as inverse replica of SBA-15, HMS and MCM-41 silica templates, with a large pore diameter (2-4 nm), a BET surface area of 1867, 874 and 910 m2g–1 respectively for CA_SBA-15_LPG_105, CA_HMS_LPG_80 and CA_MCM- 41_LPG_80 with bimodal pore size distribution (PSD) in the mesopores range. The results obtained show that mesoporous carbon with graphitic structures can be synthesized via the LPG route. / South Africa

El presente trabajo describe la síntesis y caracterización de una serie de membranas híbridas organo-inorgánicas de intercambio iónico para su uso en pilas de combustible. Las membranas se prepararon por casting a partir de dispersiones de una serie de cargas inorgánicas fenil sulfonadas en disoluciones de Nafion, por una parte y poli estiren etilen/butilen estireno (SEBS) sulfonado. Como cargas se emplearon sílica gel, SBA-15 y sepiolita, todas ellas funcionalizadas con grupos de ácido fenilsulfónico. La sepiolita y la sílica gel se funcionalizaron anclando el grupo fenilo, al sólido. Se preparó la SBA-15 mediante una reacción sol-gel. Se funcionalizó mediante dos técnicas. El primer método consistió en funcionalizar en la síntesis y el segundo en funcionalizar la SBA-15 ya preparada al igual que las otras cargas. Se llevó a cabo una sulfonación heterogénea empleando una atmósfera de SO3 como agente sulfonante. El SEBS se sulfonó en disolución utilizando sulfato de acetilo como agente sulfonante. Posteriormente se preparó una disolución con el polímero sulfonado en THF/Etanol. Para las membranas Nafion se empleó una disolución comercial al 5% en alcoholes de bajo peso molecular. Se han caracterizado en primer lugar las cargas inorgánicas mediante medida de la capacidad de intercambio iónico y análisis elemental. De esta manera se seleccionaron las cargas a incorporar en las membranas. Con las cargas definitivas se ha hecho un ensayo de adsorción isoterma de N2 con el fin de obtener la superficie específica, un análisis termogravimétrico y se utilizó el SEM para determinar el tamaño de partícula. Las membranas se han caracterizado mediante absorción de agua, capacidad de intercambio iónico, SEM, TGA, DSC, DMA, FTIR y medida de la conductividad protónica por espectroscopía de impedancia. Del análisis microestructural se determinó que la sepiolita es la carga que proporciona mejores propiedades mecánicas a las membranas debido a su menor tamaño de partícula que p / Fernández Carretero, FJ. (2009). Síntesis y caracterización de membranas híbridas organo-inorgánicas para su uso en pilas de combustible [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/4325

Despite the increasing importance of digitization in all facets of teaching and learning, digital moderation (eModeration) has received little attention in research and practice. No evidence-based requirements on the secondary school environment could be found for the development of a digital moderation system. This finding provided the rationale for an investigation into the requirements for an efficient eModeration system for IT and CAT assessments at grade 12 level in South Africa. A critical literature review was employed to explore eModeration and the requirements for a digital moderation system. This study is novel in exploring the applicability of post-adoption technology acceptance models to a pre-adoption system. The inquiry was guided by the overarching research question of: What are the requirements for an efficient eModeration system for IT and CAT SBA assessments at grade 12 level in SA? This dissertation concludes that there is currently no dedicated eModeration system in use in the secondary school environment. This study draws on the eModeration literature, the technology adoption literature and empirical research in the private secondary school environment of IT and CAT assessments at grade 12 level in South Africa to provide an evidence-based contribution to the requirements for an efficient eModeration system. The findings serve as a theoretical basis for future research into eModeration systems and can make a practical contribution to future practices and policies within schools and assessment bodies. / School of Computing / M. Sc. (Computing)