Biotin Protein Ligase (BPL) is an essential enzyme responsible for the covalent attachment of biotin to a specific lysine residue of biotin-dependent carboxylases, transcarboxylases and decarboxylases. Due to the fundamental processes that these enzymes are involved in such as lipogenesis, amino acid catabolism and gluconeogenesis, much research has been conducted on these enzymes. Studies encompassing structural, mutational and catalytic functions of these enzymes have lead to novel drug developments for the treatment of obesity, diabetes, metabolic syndrome, bacterial and fungal infections. As BPL is required for activation of these enzymes by biotinylation, it is believed that it too could be targeted in a similar way to produce novel therapeutics. To date, the most characterised BPLs are from the Gramnegative bacteria Escherichia coli and the archea Pyrococcus hirokoshii. However minimal information is known about other forms of clinically important bacterial species or eukaryotic forms of this important enzyme. Through my candidature I have compiled a thorough literature review summarised as chapter 1: Introduction. Furthering this literature analysis, a human BPL model was generated with aid of BPL structural co-ordinates already deposited in the protein data bank (PDB), thus allowing focus on human BPL mutations that cause multiple carboxylase deficiency (chapter 2). I have solved the structure of BPL from the clinically important pathogenic bacteria Staphylococcus aureus. This was performed in several ligand-bound and non-bound states (chapters 3 and 4). A novel high-throughput assay was developed to test BPL activity. This assay allow testing of compounds that could potentially inhibit the BPL from Candida albicans (a species responsible for invasive fungal infections) (chapter 5). Large amounts of highly purified BPL from Saccharomyces cerevisiae allowed for the first structural analysis of a eukaryotic BPL (Chapter 6). The work has been summarised by a general discussion and future directions for the project (Chapter 7). / Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2009

Thesis (Ph.D.); Submitted to The University of California at Berkeley, Berkeley, CA (US); 1 Sep 2003. / Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--55022" Prilliman, Gerald Stephen. USDOE Director. Office of Science. Office of Basic Energy Sciences (US) 09/01/2003. Report is also available in paper and microfiche from NTIS.

Τα νανοϋλικά, τα υλικά δηλαδή που οι διαστάσεις τους είναι στην νανοκλίμακα, έχουν διαφορετικές ιδιότητες από τα αντίστοιχα υλικά σε μεγαλύτερη κλίμακα. Για αυτό το λόγο, τα νανοϋλικά παρουσιάζουν ιδιαίτερο ενδιαφέρον για περαιτέρω μελέτη και έρευνα. Σε αυτά τα υλικά ανήκει και το οξείδιο του ψευδαργύρου (ZnO). Το οξείδιο του ψευδαργύρου είναι ένας σύνθετος ημιαγωγός τύπου II-IV με άμεσο ενεργειακό χάσμα (Eg=3.37 eV) σε θερμοκρασία δωματίου και με μεγάλη ενέργεια σύνδεσης εξιτονίου (60 meV). Σκοπός της παρούσας διπλωματικής εργασίας είναι η σύνθεση, ο χαρακτηρισμός και η μελέτη ιδιοτήτων νανοσύνθετων υλικών οξειδίου του ψευδαργύρου. Προς αυτόν τον σκοπό, θα παρασκευάσουμε νανοδομές ZnO, με τη μέθοδο του ατμού-υγρού-στερεού (VLS), σε τριζωνικό φούρνο. Στην πορεία της εργασίας, στο πρώτο κεφάλαιο θα δοθούν οι ορισμοί της νανοτεχνολογίας και των νανουλικών. Στο δεύτερο κεφάλαιο, θα αναλυθεί η δομή και οι ιδιότητες του οξειδίου του ψευδαργύρου (ZnO), βάσει των κυρίων μεθόδων ανάπτυξης των νανοδομών του ZnO. Στο τρίτο κεφάλαιο, θα γίνει ανάλυση των μεθόδων χαρακτηρισμού των νανοδομών του ZnO,που θα ακολουθήσουμε στην παρούσα εργασία. Στο επόμενο κεφάλαιο (4ο), θα παρουσιαστεί η μέθοδος παρασκευής των νανοδομών του ZnO και στο αμέσως επόμενο, παρουσιάζονται τα αποτελέσματα του χαρακτηρισμού των νανοδομών ZnO, με τις μεθόδους PL, SEM και XRD. Στο τελευταίο κεφάλαιο αναφέρονται τα συμπεράσματα που προέκυψαν από την παρούσα διπλωματική εργασία. / Nanomaterials, materials on the scale of a few nanometers, have different properties in comparison with larger-scale materials. For this reason, nanomaterials are of particular interest for further study and research. Zinc Oxide (ZnO) belongs to these materials. ZnO is a complex II-VI semiconductor with a direct band-gap energy (Eg = 3.37 eV) at room temperature and a large exciton binding energy (60 meV). The aim of the present diploma thesis, is the preparation, the characterization and the study of the properties of ZnO nanoparticles. In order to accomplish that, we are going to produce nanostructures of ZnO, using the Vapor-Solid-Solid method, in a three-zone furnace. In the first chapter, we give the definitions of nanomaterials and various methods of producing them. In the chapter that follows, we are analyzing the properties of ZnO, the main methods of producing nanostructures of ZnO as well as the ways of exploiting these specific nanostructures. Thereafter, in chapter three, the three methods of characterizing the samples with the nanostructures, are analyzed. In the next chapter, the experimental procedure is presented, whereas on the fifth chapter the results are presented, using the methods of SEM, PL and XRD. In the final chapter we make about conclusion about this diploma thesis

O aço inoxidável hiperduplex possui alta resistência a corrosão por pite em ambientes contendo cloretos, quando comparado a outros aços inoxidáveis comercialmente conhecidos. Possui boas propriedades mecânicas, com limite de escoamento superior a 700MPa e limite de resistência a tração em torno de 1000MPa. Essas propriedades o tornam muito atrativos para aplicações em ambientes contendo cloretos, e por isso tem tido destaque na indústria de óleo e gás, refinarias, plataformas offshore, etc. A liga hiperduplex é composta por uma estrutura bifásica, contendo proporções aproximadamente iguais de ferrita e austenita. Esse material possui boa soldabilidade, mas por ser termodinamicamente metaestável, em altas temperaturas pode ocorrer a precipitação de fases intermetálicas não desejáveis, o que resulta em perda de propriedades mecânicas e diminuição da resistência a corrosão. A fase sigma tem sido fortemente estudada, pois é comum sua precipitação nos aços inoxidáveis da família duplex durante o procedimento de soldagem se este não for muito bem controlado. A fase sigma precipita preferencialmente na fase ferrítica, devido a maior concentração de Cr e Mo, que são os elementos formadores da fase. A resistência a corrosão é reduzida e as propriedades mecânicas do material são alteradas o tornando frágil devido a presença da fase sigma. É formada entre 600C e 1000C e possui uma estrutura tetragonal complexa. O objetivo do trabalho foi identificar a possível presença da fase sigma na junta soldada do aço inoxidável hiperduplex SAF 2707 HD (UNS S32707) pelo processo TIG autógeno manual através da difração de raios-x. Nessa pesquisa, foram analisadas uma junta soldada do material pelo processo TIG autógeno manual com arco pulsado. Complementando o estudo foram analisadas seis amostras do aço inoxidável superduplex, sendo que cinco amostras sofreram tratamento térmico para a proposital formação da fase sigma. O refinamento do resultado da difração das amostras foi feito utilizando o método de Rietveld no software Topas Academic versão 4.1. O resultado da amostra soldada de hiperduplex apresentou as fases austenita, ferrita e alguns prováveis óxidos. Os resultados das amostras de superduplex tratadas termicamente apresentaram a fase sigma, conforme esperado na pesquisa, e as fases austenita e ferrita. / Hyperduplex stainless steel has high pitting corrosion resistance in chloride enviroments, when they were compared to other commercially stainless steel. It has good mechanical properties, with yield strength exceeding 700MPa and tensile strength limit around 1000MPa. These properties make it very attractive for applications in chlorides environments, and for this reason had been emphasis on applications for oil and gas industry, refineries, offshore platforms, etc. The alloy hyperduplex is composed of a biphasic structure, containing approximately the same proportions of ferrite and austenite. This material has good weldability, but as it is thermodynamically metastable, at high temperatures can occur the precipitation of undesired intermetallic phases, resulting in loss of mechanical properties and reduced corrosion resistance. The sigma phase has been much investigated because their common precipitation in the different kinds of duplex stainless steels during the welding procedure if not well controlled. The sigma phase use to precipitate preferentially in the ferritic phase, because of the higher concentration of Cr and Mo, which are the elements of the phase formation. This phase reduces corrosion resistance and modify the mechanical properties making the material brittle. The sigma phase is formed between 600C and 1000C and has a tetragonal complex structure. The aim of this study is characterize the phases of an hyperduplex welded join SAF 2707 HD (UNS S32707) for TIG manual autogenous process and the cry size. In this research was analyzed an welded joint of the material for autogenous arc pulsed TIG manual. Complementing the study, six superduplex stainless steel samples were analyzed, and five of this were subjected to heat treatment for the purposeful sigma formation. The samples were analyxed for x-ray diffraction technique. The refinement results were done by Rietveld Method in Topas Academic 4.1 version software. The welded join of hyperduplex showed the austenite, ferrite and some probable oxides. The results of the heat treated samples of superduplex showed the sigma phase, as expected in this research, and the austenite and ferrite phases.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work describes the synthesis and structural analysis of different kinds of tellurium based compounds, depicting the preparation of zwitterions, coordination polymers and also heteronuclear complexes, using 4-ditellurobispyridine (4) and N , N , N , N -tetraethyl-N,N -pyridine-2,6-dicarbonyl-bis(thiourea) (12) as starting materials. These ligands are able to form complexes with tellurium allowing the simultaneous coordination of transition metals, producing novel compounds. The materials were characterized by single crystal X-ray diffraction, vibrational spectroscopy and 1H and 125Te nuclear magnetic resonance (when applicable). The methodology using the ligand 12 provided the preparation of three different classes of compounds: complexes with inorganic tellurium, complexes with organic derivatives of tellurium and tellurium based complexes with transition metals. The later ones are the most interesting owing the selectivity of the ligand, that coordinates to tellurium just with the softer site (sulfur atom), leaving the other donor atoms free to coordinate to another metallic center. / Este trabalho apresenta a síntese e a análise estrutural de diferentes classes de complexos derivados de telúrio, com a obtenção de zwitterions, polímeros de coordenação, e também, complexos heteronucleares, a partir de ditelureto de bis-4-piridila (4) e do ligante N , N , N , N -tetraetil-N,N -piridina-2,6- dicarbonil-bis(tioureia) (12). Os ligantes utilizados neste trabalho são capazes de formar complexos com telúrio permitindo a coordenação simultânea de metais de transição, de tal modo que as metodologias de síntese empregadas são capazes de fornecer compostos inéditos na literatura. Os materiais foram caracterizados por difração de raios-X em monocristal, espectroscopia no infravermelho, análise elementar, e ressonância magnética nuclear de 1H e de 125Te nos exemplos em que as técnicas são aplicáveis. As metodologias envolvendo o ligante 12 permitiram a obtenção de três classes distintas de compostos: complexos com telúrio inorgânico, com derivados orgânicos de telúrio e complexos em combinação com metais de transição. Os complexos envolvendo metais de transição têm especial destaque, pois o ligante 12 mostrou excelente seletividade, ocorrendo a coordenação ao átomo de telúrio exclusivamente pelo sítio macio (átomo de enxofre), deixando os outros sítios doadores livres para coordenação com outro centro metálico.

Ce travail porte sur la synthèse et la caractérisation d’oxydes de manganèse de formule généraleCaxMnyOz avec y/x > 1. Par une approche de chimie du solide, les propriétés redox de ces matériauxseront corrélées à leur composition chimique et leur structure cristalline ce qui constitue une étude enamont de l’application pour ces systèmes pouvant jouer le rôle de tampon à oxygène dans desprocessus catalytiques. Les composés ont été synthétisés par autocombustion en voie aqueuse etcaractérisés d’un point de vue structural. Les propriétés redox ont été évaluées par ATG et lespropriétés de réductibilité par H2-TPR pour certains composés. Quelles que soient la structure, ladimensionnalité ou la valence du manganèse dans les composés oxydés (Mn4+/Mn3+), le manganèsese réduit totalement en Mn2+ sous atmosphère réductrice (Ar/H2). Les composés réduits cristallisentdans une solution solide de type NaCl de formule Ca1-xMnxO. Les mécanismes de réduction dumanganèse au sein de ces structures ont été appréhendés sur la base des analysesthermogravimétriques. Afin de faire varier les températures de réduction, l’iono-covalence de la liaisonMn-O a été modifiée via des substitutions cationiques (i) sur les sites du calcium principalement ausein de réseaux 2D ou (ii) sur les sites du manganèse essentiellement dans les réseaux 3D avec laprésence d’Al3+ ou de Fe3+ de rayons ioniques comparables respectivement à Mn4+ et Mn3+. Lessolutions solides ont été caractérisées d’un point de vue structural mais aussi pour leurs propriétésredox. Il convient de souligner que les phases substituées au Fer présentent des propriétés redox toutà fait remarquables dans la mesure où les ions Fe3+ tout comme Mn4+/3+ se réduisent d’abord en Fe2+puis en Fe° qui est dès lors expulsé hors de la matrice oxyde. Lors de la réoxydation, le fer réintègrele réseau 3D et les matériaux sont cyclables dans des conditions réductrices puis oxydantes à l’air àdes températures inférieures à 1000°C. / This work deals with the synthesis and characterization of manganese oxides with CaxMnyOz formulaand y/x >1. According to a solid state chemistry scope, the redox properties of these materials will becorrelated to their chemical composition and crystallographic structure which constitutes a forehandexploratory study of compounds that are intended to be used for the automotive catalysis exhaustbased on the three-way catalysis principle. The materials were synthesized by aqueous selfcombustionroute and structurally characterized. Redox properties and reducibility properties wereevaluated by TGA and H2-TPR, respectively. Whatever the structure, the dimensionality of the networkor the manganese valence in the starting oxidized material, all of the manganese ions are completelyreduced (Mn2+) in a Ar/H2 atmosphere. The reduced compounds crystallize in a rock-salt type solidsolution with the formula Ca1-xMnxO. The mechanisms of manganese reduction within these structureswere explored on the basis of TGA analysis. In order to tune the reduction temperatures, the ionocovalenceof the Mn-O bond has been modified by either cationic substitution of calcium in the 2Dnetworks or either substitution of manganese in the 3D networks. In this last case, Substituting ionswere Al3+ and Fe3+ which ionic radii comparable to Mn4+ and Mn3+, respectively. Solid solutions havebeen characterized from a structural point of view but also for their redox properties. One shouldnotice that iron substituted compounds exhibit remarkable redox properties because Fe3+ ions firstreduce in Fe2+ iron before a final reduction in Fe° that is consequently expulsed from the matrix. Atreoxidation, iron returns into the 3D network and cycling can be observed when reducing and oxidizingat temperatures lower than 1000°C.

Made available in DSpace on 2014-12-17T14:06:58Z (GMT). No. of bitstreams: 1 JoaoBM.pdf: 4159366 bytes, checksum: 0675996da75ecb96ee8b23855ac7f866 (MD5) Previous issue date: 2008-05-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This work a studied the high energy milling effect in microstructure and magnetic properties of the WC-10wt.%Co composite. The composite powders were prepared by mechanical mixed and milled at 2 hours, 100 hours, 200 hours and 300 hours in planetary milling. After this process the composite were compacted in stainless steel die with cylindrical county of 10 mm of diameter, at pressure 200 Mpa and sintered in a resistive furnace in argon atmosphere at 1400 oC for 5 min. The sintered composite were cutted, inlaid, sandpapered, and polished. The microestrutural parameters of the composite was analyzed by X-ray diffraction, scanning electronic microscopy, optical microscopy, hardness, magnetic propriety and Rietveld method analyze. The results shows, with milling time increase the particle size decrease, it possibility minor temperature of sintering. The increase of milling time caused allotropic transformation in cobalt phase and cold welding between particles. The cold welding caused the formation of the particle composite. The X-ray diffraction pattern of composite powders shows the WC peaks intensity decrease with the milling time increase. The X-ray diffraction pattern of the composite sintered samples shows the other phases. The magnetic measurements detected a significant increase in the coercitive field and a decrease in the saturation magnetization with milling time increase. The increase coercitive field it was also verified with decrease grain size with milling time increase. For the composite powders the increase coercitive field it was verified with particle size reduction and saturation magnetization variation is relate with the variation of free cobalt. The Rietveld method analyze shows at milling time increase the mean crystalline size of WC, and Co-cfc phases in composite sintered sample are higher than in composite powders. The mean crystallite size of Co-hc phase in composite powders is higher than in composite sintered sample. The mean lattice strains of WC, Co-hc and Co-cfc phases in composite powders are higher than in composite sintered samples. The cells parameters of the composite powder decrease at milling time increase this effect came from the particle size reduction at milling time increase. In sintered composite the cells parameters is constant with milling time increase / O presente trabalho estudou o efeito da moagem de alta energia nos par?metros microestruturais e nas propriedades magn?ticas do comp?sito WC-10%pCo. Os p?s comp?sitos foram processados em moinho planet?rio por mistura mec?nica e mo?dos por 2 h, 100 h, 200 h e 300 h. Os comp?sitos em p? foram compactados numa matriz de 10 mm de di?metro a uma press?o de 200 Mpa e sinterizadas a 1400 0C/ 5 min no forno acoplado ao dilat?metro com atmosfera de arg?nio. Os comp?sitos foram submetidos a um processamento metalogr?fico de corte, embutimento, lixamento e polimento. A caracteriza??o dos comp?sitos consistiu em difra??o de raios-X, microscopia ?ptica, microscopia eletr?nica de varredura, dureza, propriedades magn?ticas e an?lise dos par?metros microestruturais pelo m?todo de Rietveld. Os resultados mostram que o tempo de moagem promove uma redu??o do tamanho de part?cula. Os comp?sitos com maior tempo de moagem sinterizam a menor temperatura. O tempo de moagem promove ainda a soldagem a frio das part?culas originando a forma??o de part?culas comp?sitas e transforma??es alotr?picas na fase cobalto. O difratograma de raios-X para os p?s comp?sitos mostra uma queda da intensidade dos picos de WC com o tempo de moagem. O difratograma de raios-X para os comp?sitos sinterizados mostra a presen?a de outras fases. As medidas magn?ticas detectaram um decr?scimo na magnetiza??o de satura??o e um crescimento no campo coercitivo com o aumento do tempo de moagem. Com o tempo de moagem foi verificado um decr?scimo do tamanho de gr?o. Para os p?s comp?sitos o aumento do campo coercitivo est? relacionado com a redu??o do tamanho de part?cula e a varia??o da magnetiza??o de satura??o est? relacionada com a varia??o do cobalto livre. O m?todo de Rietveld mostrou que a varia??o do tamanho m?dio do cristalito com o tempo de moagem das fases WC e Co-cfc foi menor nos comp?sitos sinterizados do que nos p?s comp?sitos. J? na fase Co-cfc esta varia??o foi maior nos p?s. A deforma??o m?dia do cristalito das fases WC, Co-hc e Co-cfc ? maior nos p?s comp?sitos do que nos comp?sitos sinterizados. Nos p?s comp?sitos os par?metros de rede para as fases WC, Co-hc e Co-cfc decrescem com o tempo de moagem. Este decr?scimo est? diretamente influenciado pela redu??o do tamanho das part?culas. Para os comp?sitos sinterizados os par?metros de rede para as fases WC, Co-hc e Co-cfc s?o praticamente constantes

Made available in DSpace on 2014-12-17T14:08:34Z (GMT). No. of bitstreams: 1 TiagoRS.pdf: 224853 bytes, checksum: a7ecf3c3cba57ff6b3ea1ac7c4fb7f05 (MD5) Previous issue date: 2009-06-02 / Petr?leo Brasileiro SA - PETROBRAS / Cementation operation consists in an extremely important work for the phases of perforation and completion of oil wells, causing a great impact on the well productivity. Several problems can occur with the cement during the primary cementation, as well as throughout the productive period. The corrective operations are frequent, but they are expensive and demands production time. Besides the direct cost, prejudices from the interruption of oil and gas production till the implementation of a corrective operation must be also taken into account. The purpose of this work is the development of an alternative cement paste constituted of Portland cement and porcelainized stoneware residue produced by ceramic industry in order to achieve characteristics as low permeability, high tenacity, and high mechanical resistance, capable of supporting various operations as production or oil wells recuperation. Four different concentration measures of hydrated paste were evaluated: a reference paste, and three additional ones with ceramic residue in concentrations of the order of 10%, 20% and 30% in relation to cement dough. High resistance and low permeability were found in high concentration of residues, as well as it was proved the pozolanic reactivity of the residue in relation to Portland cement, which was characterized through x-ray and thermogravimetry assays. It was evident the decrease of calcium hydroxide content, once it was substituted by formation of new hydrated products as it was added ceramic residue / A opera??o de cimenta??o consiste em um trabalho de extrema import?ncia para as fases de perfura??o e completa??o de po?os de petr?leo e tem grande impacto sobre a produtividade do po?o. Muitos problemas podem ocorrer com o cimento, tanto durante a cimenta??o prim?ria do po?o como tamb?m durante seu per?odo produtivo. As opera??es para corre??o destes problemas s?o freq?entes, por?m onerosas e demandam tempo de produ??o. Al?m do custo direto da opera??o corretiva, deve m ser ontabilizados, ainda, preju?zos devidos ? interrup??o da produ??o de ?leo e g?s at? que uma opera??o de corre??o seja realizada. Este trabalho tem como objetivo o desenvolvimento de pastas cimentantes alternativas, constitu?das por cimento Portland e um res?duo de porcelanato produzido pela ind?stria cer?mica, a fim de obter caracter?sticas como baixa permeabilidade, alta tenacidade e alta resist?ncia mec?nica, capazes de suportar as diversas opera??es, tanto de produ??o como de recupera??o de po?os de petr?leo. Foram avaliadas quatro concentra??es diferentes de pastas hidratadas: uma pasta de refer?ncia e tr?s pastas contendo res?duo cer?mico nas concentra??es de 10%, 20% e 30%, em rela??o ? massa do cimento. Foram encontradas, para as maiores concentra??es de res?duo, maior resist?ncia mec?nica e menor permeabilidade, al?m de ser comprovada a reatividade pozol?nica do res?duo com o cimento Portland. Esta foi caracterizada atrav?s dos ensaios de Difra??o de Raios X e Termogravimetria, ficando clara a diminui??o do teor de hidr?xido de c?lcio, substitu?do pela forma??o de novos produtos hidratados ? medida que se adicionava o res?duo cer?mico

Made available in DSpace on 2014-10-09T12:36:59Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:24Z (GMT). No. of bitstreams: 1 04491.pdf: 3155069 bytes, checksum: aa854e4a23f31eb334f216ec1ea726c2 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:37:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:46Z (GMT). No. of bitstreams: 1 01909.pdf: 4337748 bytes, checksum: 86acf59a272732a64c336ea3408816ec (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP