The aim of this thesis was to improve the understanding of microstructure in single crystal ferroelectrics. This was achieved through macroscopic testing of Lead Magnesium Niobate – Lead Titanate (PMN-PT) and microscopic observations of Barium Titanate (BT) single crystals. Multi-axial polarization rotation tests on PMN-PT showed a gradual increase in the change in dielectric displacement due to ferroelectric switching as the electric field is applied at increasing angles to the initial polarization direction. A relatively high remnant polarization for loading angle near to 90° suggested that PMN-PT is more polarizable in certain directions. Strains measured in two directions, parallel to the electric field and perpendicular to the electric field, showed a noticeable variation on two opposite faces of the specimen suggesting an effect of local domain configurations on macroscopic behaviour. A micromechanical model gave an insight into the switching systems operating in the crystal during the polarization rotation test. Domain structure in BT was mapped using synchrotron X-ray reflection topography. By making use of the angular separation of the diffracted reflections and specimen rocking, different domain types could be unambiguously identified, along with the relative tilts between adjacent domains. Fine needle domains (width ≈ 10μm) were successfully mapped providing a composite topograph directly comparable with optical micrograph. The domain structure was confirmed using other techniques such as piezoresponse force microscopy and atomic force microscopy/scanning electron microscopy and optical observations on the etched crystal. Results show that combined use of multiple techniques is necessary to gain a consistent interpretation of the microstructure. Finally, domain evolution in BT under compressive mechanical loading was observed in-situ using optical and X-ray diffraction techniques providing a series of images that show ferroelastic transition. The domain configurations influence the switching behaviour and constitutive models that can account for such effects need to be developed. Quantitative and qualitative data presented in this thesis can assist model development and validation.

Solid state chemical storage of hydrogen in metals offers promising advantages over compressed hydrogen gas and condensed liquid hydrogen, especially for mobile applications with respect to safety and energy efficiency. However, no single metal hydride simultaneously satisfies the essential performance criteria for onboard hydrogen storage namely, high gravimetric and/or volumetric energy density, fast kinetics and favorable thermodynamics. Recently, a breakthrough achievement was made by the development of reactive hydride composites in which two metal hydride systems (e.g. NaBH₄ and MgH₂) are mixed together resulting in better sorption properties than the individual pure systems. In this approach, the formation of MgB₂ by exothermic reaction destabilizes the composite and consequently reduces the overall enthalpy and sorption temperature of the endothermic desorption reaction. In this work the thermodynamic and kinetic properties of reactions in 2NaH + MgB₂ + 4H₂ ↔ 2NaBH₄ + MgH₂ and 3NaH + MgB₂ + 4H₂ ↔ 2NaBH₄ + NaMgH₃ were established using multiple experimental techniques like volumetric measurements, ex-situ and in-situ X-ray diffraction, calorimetry, and especially electron microscopy. Under the applied experimental conditions of 50 bar hydrogen and 400 °C during the hydrogenation of 2NaH + MgB2 and 0.1 bar hydrogen and 450 °C during the dehydrogenation of 2NaBH₄ + MgH₂, both reactions were kinetically limited and proceeded in multisteps. The absorption reaction was partial, being restricted by the unexpected formation of NaMgH₃ which limits the formation of NaBH₄ while the desorption reaction was complete and limited by the growth of MgB₂ through some intermediate complexes at the Mg/NaBH₄ interface where the intermediate phase forms a barrier to diffusion. Conversely, in the 3NaH + MgB₂ system, absorption in 100 bar hydrogen and 300 °C was complete but slow, while in the 2NaBH₄ + NaMgH₃ system, complete desorption was achieved in multisteps under 0.1 bar hydrogen and 450 °C. The formation of intermediate and stable complexes during these reactions poses a significant restraint to hydrogen sorption reactions. However, lower onset sorption temperatures have been established in these systems than in the pure compounds due to their simultaneous destabilization in the composite state. This study have demonstrated the complexity of desorption and absorption mechanisms in these composite systems and the difficulty of obtaining such reactions at low temperatures required for mobile applications. This understanding of the rate limiting reaction steps in reactive hydride composites provides the basis for further optimization of these materials for efficient hydrogen storage applications.

This thesis presents details of x-ray and neutron scattering experiments used to probe quantum magnets with strong spin-orbit interaction. The first of these systems are the three-dimensional iridate compounds, in which the three-fold co-ordination of IrO₆ octahedra has been theoretically hypothesized to stabilize anisotropic exchange between Ir⁴⁺ ions. This novel interaction between these spin-orbital entangled, J_eff=1/2 moments is described by a Hamiltonian first proposed by Kitaev, and would be the first physical realization of this Hamiltonian in a condensed matter system. This thesis details the determination of the structure of a new polytype within these compounds, the 'stripyhoneycomb' &gamma;-Li₂IrO₃. Furthermore, through resonant magnetic x-ray diffraction experiments on single crystals of &beta;-Li₂IrO₃ and &gamma;-Li₂IrO₃, an incommensurate, non-coplanar structure with counter-rotating moments is found. The counter-rotating moment structure is a rather counter-intuitive result, as it is not stabilizied by Heisenberg exchange between magnetic sites, however, the Kitaev exchange naturally accounts for this feature. As such, these experiments reveal, for the first time, systems which exhibit dominant Kitaev interactions. The ordering wavevector of both &beta;- and &gamma;-Li₂IrO₃ polytypes are found to be identical, suggesting that the same magnetic interactions are responsible for stabilizing magnetic order in both materials, despite their different lattice topologies. Following this, the spinel FeSc₂S₄ is considered. Here, despite the presence of strong exchange between Fe<sup>2+,/sup>, and the fact that these ions sit in a Jahn-Teller active environment, the system does not order in the spin or orbital degrees of freedom. A 'spin-orbital singlet' has been theoretically proposed to describe the groundstate of this system, and here inelastic neutron scattering (INS) is used to probe the resulting triplon excitations. This allows determination of microscopic parameters in the single ion and exchange Hamiltonians, and moreover experiments in external magnetic field reveal the true spin-and-orbital nature of these triplon excitations. Finally, Ba₃CoSb₂O₉, a physical realization of the canonical triangular antiferromagnet model is explored with INS and the high energy excitations from the 120 degree magnetic structure are found to display significant differences from those calculated by linear spin wave theory, suggesting the presence of quantum dynamics not captured in the 1/S linear spin wave expansion.

Shape memory alloys (SMAs) represent a revolutionary class of active materials that can spontaneously generate strain based on an environmental input, such as temperature or stress. SMAs can provide potential solutions to many of today's engineering problems due to their compact form, high energy densities, and multifunctional capabilities. While many applications in the biomedical, aerospace, automotive, and defense industries have already been investigated and realized for nickel-titanium (NiTi) based SMAs, the effects of controlling and designing the microstructure through processing (i.e. extreme cold working) have not been well understood. Current Ni-Ti based SMAs could be improved upon by increasing their work output, improving dimensional stability, preventing accidental actuation, and reducing strain localization. Additionally, there is a strong need to increase the transformation temperature above 115 °C, the current limit for NiTi and is especially important for aerospace applications. Previous research has shown that the addition on ternary elements such as Au, Hf, Pd, Pt, and Zr to NiTi can greatly increase these transformation temperatures. However, there are several limiting factors with these ternary additions such as increased cost, especially with Au, Pd, and Pt, as well as, difficulty in conventionally processing these alloys. Therefore, the main objectives of this research is to study how processing can alter the mechanical properties of NiTi and characterizing it using in situ synchrotron radiation x-ray diffraction (SR-XRD), understanding how we can process ternary SMAs (NiTiHf) by conventional means, and lastly how this processing alters precipitation characteristics and mechanical properties of these alloy systems.

O pró-fármaco antimetabólito 5-Fluorocitosina (5-FC) foi investigado no campo da Engenharia de Cristais (EC) segundo a abordagem de cocristais farmacêuticos, a fim de modular sua baixa estabilidade física em ambientes úmidos, o que leva à incorporação irreversível de uma molécula de água a nível estrutural em condições de armazenamento variáveis. A forma anidra da 5-FC é um análogo fluorado da citosina muito bem conhecido por sua atividade antifúngica e com isto tornou-se um dos insumos farmacêuticos ativos (IFAs) mais utilizados para o tratamento anticâncer direcionado por meio de terapia gênica. Neste estudo, novos cocristais de 5-FC foram obtidos a partir da reação supramolecular deste IFA com o IFA tuberculostático Isoniazida (INH), bem como com outros três coformadores listados como não tóxicos: cafeína (CAF), ácido p-aminobenzóico (PABA) e ácido caprílico (CA). As amostras foram caracterizadas por difração de raios X em monocristal e policristal (DRXM e DRXP), espectroscopia na região do infravermelho (IV) e espalhamento Raman (Raman); assim como pelas técnicas de análise termogravimétrica (TG), calorimetria exploratória diferencial (CED) e microscopia termo-óptica (MTO). A estabilidade física da 5-FC e seus respectivos cocristais foi avaliada em ambiente com aproximadamente 100% de umidade relativa e a solubilidade no equilíbrio medida em meio tamponado a pH 1,2 &ndash; mimetizando valores próximos ao do suco gástrico. Os estudos estruturais mostraram que a 5-FC é capaz de formar diferentes homo e heterossíntons que levam à formação de formas multicomponentes estáveis. Dados de IV e Raman forneceram evidências espectroscópicas sobre o envolvimento dos grupos funcionais na manutenção dos principais síntons e, por tanto, do empacotamento cristalino, confirmando assim a natureza neutra necessária para a obtenção de um cocristal. Pelas análises térmicas foi possível observar que todas as amostras apresentaram uma maior preferência pela degradação do que pela mudança da fase sólida para a líquida com o fornecimento de calor, corroborando que as ligações intermoleculares de hidrogênio que mantém estas formas sólidas são fortes. Adicionalmente, constatou-se que os perfis de solubilidade dos quatro cocristais são similares ao IFA de partida, um fármaco classificado como de classe I pelo Sistema Biofarmacêutico, exibindo, assim, alta solubilidade. A instabilidade frente à hidratação bem como sua irreversibilidade foram estudadas por DRXP à temperatura ambiente (25 °C) e por DRXP em função da temperatura (até 150 °C), respectivamente. Nos cocristais, por sua vez, nenhuma transição de fase pode ser assinalada. Deste modo, todos os cocristais de 5-FC aqui reportados mantiveram uma solubilidade aceitável e não hidrataram ou sofreram transição de fase sob condições extremas de armazenamento (estudo de estabilidade acelerada em atmosfera úmida) e muito menos ao final de 12 meses de estoque (estudo de estabilidade a longo prazo), sendo mais estáveis que o IFA 5-FC forma comercializada. Além disso, o cocristal fármaco-fármaco intitulado 5FC-INH é um potencial candidato para o tratamento concomitante de infecções fúngicas, tuberculose e câncer; principalmente de pulmão. / The prodrug antimetabolite 5-Fluorocytosine (5-FC) was investigated in the field of Crystal Engineering (CE) according to the Pharmaceutical Cocrystals approach, in order to modulate its poor physical stability in humid environments, which leads to the irreversible incorporation of a water molecule at structural level under variable storage conditions. 5-FC anhydrous form is a well-known fluorinated analog of cytosine with antifungal activity and it has become one of the most used active pharmaceutical ingredients (IFAs) for anticancer treatment directed through gene therapy. In this study, novel 5-FC cocrystals were obtained from the reaction of 5-FC with the tuberculostatic IFA Isoniazid (INH) as well as with other three coformers listed as nontoxic: caffeine (CAF), p-aminobenzoic acid (PABA) and caprylic acid (CA). The samples were characterized by single-crystal and powder X-ray diffraction (SCXRD and PXRD), spectroscopic (IR and Raman) and thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Hot-Stage microscopy (HSM) techniques. The physical stability of 5-FC and its cocrystals were evaluated in environment with high relative humidity (approximately 100 %) and the equilibrium solubility was measured in pH 1.2 buffer media &ndash; mimicking values close to that of gastric juice. The structural studies show that the prodrug 5-FC is able to form different homo and heterosynthons that lead to the formation of stable multicomponent forms. IR and Raman data provided spectroscopic evidence on the involvement of functional groups in the maintenance of major synthons and crystal packing assembly, thereby confirming the neutral nature required to obtain a cocrystal. From the thermal analyses it was possible to observe that all the samples presented a preference for degradation instead of phase transition form solid to liquid with the heat supply, corroborating the strength of intermolecular hydrogen bonds that maintain these solid forms. Additionally, the solubility profiles were found to be similar to those of the 5-FC API raw material, a Biopharmaceutical System classified as Class I drug, exhibiting high solubility profile. The instability against hydration and its irreversibility was studied by PXRD at room temperature (25 °C) and by PXRD as a function of temperature (up to 150 °C), respectively. In the cocrystals, in turn, no phase transition was found. Thus, all 5-FC cocrystals reported maintained acceptable solubility and did not hydrate or undergo phase transition under extreme storage conditions (accelerated stability study in moist atmosphere) even at the end of 12 months of storage (long-term stability study), being more stable than the commercially available IFA 5-FC. Furthermore, the drug-drug cocrystal (5FC-INH) is a potential candidate for the treatment of concomitantly fungal infections, tuberculosis and cancer, mainly lung cancer.

[pt] Os laboratórios analíticos de universidades e instituições de pesquisa privadas sem fins lucrativos estão expostos a um ambiente competitivo bem como à descontinuidade e contingenciamento de recursos financeiros oferecidos pelos órgãos de fomento. Objetivando a auto-sustentabilidade operacional, esses laboratórios estão buscando fontes de recursos próprios com a oferta crescente de prestação de serviços especializados a diferentes setores industriais. Contudo, as atividades de prestação de serviço são distintas quando comparadas às atividades de P&D&I, pois as primeiras são caracterizadas pela necessidade imediata ou de curto prazo e as últimas são caracterizadas pelo longo prazo. Neste contexto, torna-se necessário avaliar o trade-off entre ambientes competitivos e cooperativos (serviços e pesquisa) e estabelecer estratégias competitivas sustentáveis, além de práticas e técnicas de gestão que garantam a eficiência operacional sem prejuízo da qualidade e do nível de atendimento do laboratório analisado. O objetivo geral deste trabalho é, portando, analisar o desempenho do LabDRX da PUC-Rio em um cenário auto-sustentável através de um modelo de simulação de eventos discretos. Conclui-se que em tal cenário o desempenho do Laboratório atende a política de atendimento acordada com as categorias de clientes, desde que se faça a implementação conjunta de limitação dos pedidos de urgência na disciplina de fila do sistema e do aumento de capacidade com uma proposta de inovação em processo, o Distance Rietveld. A metodologia apresentada neste trabalho pode ser adaptada para outros laboratórios semelhantes que procurem sustentabilidade operacional através de prestação de serviços tecnológico para indústria. / [en] Private non-profit universities and research institutes have their analytical laboratories exposed to a competitive environment, as well as to discontinuity and limitation of financial resources offered by funding agencies. Aiming to operational self-sustainability, these laboratories are searching complementary resources by increasing the offer of specialized services to different industrial sectors. However, service activities are distinct from R&D&I activities, because the former are characterized by immediate or short-term need and the latter, by long-term need. In this context, it becomes necessary to evaluate the trade-off between competitive and cooperative environments (services and research), and to establish sustainable competitive strategies, as well as management practices and techniques that assure operational efficiency without quality losses or decrease in the service level. The objective of this work is, therefore, to analyze the performance of LabDRX at PUC-Rio in a self-sustainable scenario through discrete-event simulation. It was found that, in the self- sustainable scenario considered, the performance of the Laboratory satisfies the contracting policy agreed with the customer categories, as long as one makes simultaneous implementation of a limited urgent queue discipline and a capacity increase through an innovation proposal: Distance Rietveld. The methodology presented in this work can be adapted for many other similar laboratories searching for operational sustainability by offering technological services to industry.

Orientador: João Carlos Silos Moraes / Resumo: O presente trabalho tem como objetivo a síntese e caracterização estrutural de filmes finos a base de TeO2 usando o método Pechini. Os filmes finos foram produzidos seguindo a estequiometria 80TeO2–20Li2O (% molar), utilizando como precursores metálicos o ácido telúrico (H6TeO6) e o carbonato de lítio (Li2CO3). Os materiais precursores foram solubilizados em solução aquosa de ácido cítrico sob aquecimento para obtenção de um citrato metálico, o qual foi acrescido de etilenoglicol para polimerização. A resina polimérica obtida foi depositada sobre dois diferentes substratos, vidro e silício cristalino, pela técnica de spin-coating, para a obtenção dos filmes finos. Em substratos de vidro, a pirólise ocorreu a 300°C e o tratamento térmico foi realizado à 400°C e nos substratos de Si, os filmes foram pirolisados a 500°C e tratados termicamente em 600°C. A caracterização dos filmes foi realizada por meio das técnicas de difração de raios-X, microscopia eletrônica de varredura, espectroscopia de energia dispersiva e Raman. Os filmes obtidos apresentaram espessuras da ordem de micro a nanômetros e, dos dados de Espectroscopia de Energia Dispersiva, foi possível acompanhar a transformação do Te metálico para as fases do TeO2. Dos dados de difração de raios X e Raman foi possível identificar e observar a transição entre as fases γ e α-TeO2. A qualidade dos filmes finos obtidos usando a rota estabelecida neste trabalho, demonstra a viabilidade da produção de filmes finos a base de tel... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of this work is the synthesis and structural characterization of thin films based on TeO2 using the Pechini method. The thin films were produced following the stoichiometry 80TeO2-20Li2O (mol%) using telluric acid (H6TeO6) and lithium carbonate (Li2CO3) as metallic precursors. The precursor materials were solubilized in aqueous solution of citric acid under heating to obtain a metal citrate, which was added with ethylene glycol for polymerization. The obtained polymer resin was deposited on two different substrates, glass and crystalline silicon, by the spin-coating technique, to obtain the thin films. On glass substrates, the pyrolysis occurred at 300°C and the heat treatment was performed at 400°C, and on the Si substrates, the films were pyrolyzed at 500°C and thermally treated at 600°C. The films were characterized by X-ray diffraction, scanning electron microscopy, dispersive energy and Raman spectroscopy. The films obtained presented thicknesses of the order of micro to nanometers and, from the data of Dispersive Energy Spectroscopy, it was possible to follow the transformation of the metallic Te to the phases of TeO2. From the X-ray and Raman diffraction data it was possible to identify and observe the transition between the γ and α-TeO2 phases. The quality of the thin films obtained through the route established in this work, demonstrates the practicability of the preparation of tellurium based thin films by the Pechini method. / Mestre

No Capítulo 1, os fundamentos da cristalografia de raios X estão sucintamente descritos. No Capítulo 2, seis estruturas de pequenas moléculas contendo átomos pesados em sua constituição foram determinadas. As quais são resumidas a seguir: 1)[Ru2Cl5(CO)(PPh3)3], Mr = 1194,21, cristaliza-se no sistema monoclínico, grupo espacial P21/c com a =14,618(4)&#197, b=18,043(7)&#197, c=20,31(3)&#197; &#946=99,81(5)&#176; V=5277(8)&#1973; Z=4; Dcalç =1,503g/cm-3; &#955(MoK&#945) = 0,71073&#197; &#956 = 0,954 mm-1; F(000) = 2404; R=0,538 para 9281 reflexões independentes e 487 parâmetros refinados. Os átomos de Ru estão ligados em ponte através de três ânions Cl. Um átomo de Ru é coordenado a dois outros átomos de Cl e a um ligante PPh3, o outro átomo de Ru está coordenado a dois ligantes PPh3 e a uma molécula de CO. 2)[RuCl3(dppb)H2O], Mr = 651,88, cristaliza-se no sistema ortorrômbico, grupo espacial Pbca; com a=14,932(1) &#197, b=18,133 (3)&#197, c=20,59(3)&#197; V=5576,0(1)&#1973; Z=8; Dcalc =1,553g/cm-3; &#955(MoK&#945) = 0,71073&#197; &#956 = 0,985 mm-1; F(000)=2648; R=0,0461 para 4892 reflexões independentes e 316 parâmetros refinados. O complexo é hexacoordenado. Os átomos P encontram-se em posição cis, um em relação ao outro, formando um complexo próximo de uma estrutura octaédrica. Esta estrutura apresentou interação intermolecular Cl...H. A distância entre o H de uma molécula e o Cl é de 2,48(2)&#197. 3) FeC19H1919N19S19], Mr=377,28, cristaliza-se no sistema monoclínico, grupo espacial P21/n; com a=11,715(2)&#197, b=7,830(2)&#197, c=18,728(3)&#197; &#946=91,570(1)&#176; V=1717,1(6)&#1973; Z=4; Dcalc =1,459g/cm-3; &#955(MoK&#945) = 0,71073&#197; &#956 = 1,004 mm-1; F(000)=784; R=0,0453 para 3018 reflexões independentes e 218 parâmetros refinados. O complexo é formado por um átomo de ferro decacoordenado em uma extremidade e na outra existe um anel aromático, indicando que os radicais genéricos mostrados na Seção (2.5) são R\'=C\'H IND. 3\', X=S1 e R\"=fenil. 4)[pyH][RuCl4(dmso)(py)].(CH2Cl2)1/2, Mr=562,11 cristaliza-se no sistema triclínico, grupo espacial P1; com a= 7,7608(1)&#197, b=85451(1)&#197, c=15,095(5)&#197; &#945=88,27(2)&#186; &#946=79,33(2)&#186; &#947,=88,77(1)&#186; V=983,2(4)&#1973; Z=2; Dcalc=1,899gcm-3; &#955(CuK&#945)=1,54184 &#197; &#956=15,001 mm-1; F(000)=556; R=0,0886 para 2909 reflexões independentes e 204 parâmetros refinados. O Ru está octaedricamente coordenado a quatro átomos Cl coplanares, a um N do anel de uma piridina e ao dmso, em posição trans entre si. Um outro grupo piridina protonado, que forma o cátion da estrutura, completa a estrutura. 5)[RuCl2(CO)2(AsPh3)2, Mr =840,43, cristaliza-se no sistema monoclínico, grupo espacial P21/n; com a=710,520(4)&#197, b=25,823(5)&#197, c=12,780(2)&#197; &#946=100,7401(1)&#176; V=3411,0(1)&#1973; Z=4; Dcalc =1,637gcm-3; &#955(CuK&#945)=1,54184 &#197; &#956=7,576 mm-1; F(000)=1672; R=0,0739 para 4284 reflexões independentes e 406 parâmetros refinados. O átomo de Ru está ligado a dois átomos de Cl e a duas moléculas CO, que formam aproximadamente um plano entre si. Os CO\'s estão em posição trans em relação aos Cl\'s. O átomo de Ru também apresenta coordenação com duas PPh3. 6)[Ru2ClBr4(CO)(AsPh3).CH2Cl2)<, Mr=154,88 cristaliza-se no sistema monoclínico, grupo espacial P21/c; com a=14,766(2)&#197, b=18,519(2)&#197, c=20,730(4)&#197; &#946=100,085(1)&#176; V=5581,2(1)&#1973; Dcalc =1,839gcm-3; &#955(CuK&#945)=1,54184 &#197; &#956=10,947mm-1; F (000)=3004; R=0,0955 para 5738 reflexões independentes e 493 parâmetros refinados. O complexo é formado por dois átomos de Ru em ponte através de três ânions Br. Um átomo de Ru é também coordenado a um átomo Br, a um Cl e a um ligante trifenilfosfina. O outro átomo de Ru está ligado a duas trifenilarsinas e a uma molécula de monóxido de carbono. No capítulo 3, apresentam-se as conclusões e planos futuros / In Chapter 1, the basic principles of X-ray crystallography that have been used in this work are briefly described. In Chapter 2, six small molecule structures with heavy atoms are presented. They are summarized as follows: 1)[Ru2Cl5(CO)(PPh3)3], Mr = 1194,21, crystallizes in the monoclinic system, space group P21/c com a =14,618(4)&#197, b=18,043(7)&#197, c=20,31(3)&#197; &#946=99,81(5)&#176; V=5277(8)&#1973; Z=4; Dcalc =1,503g/cm-3; &#955(MoK&#945) = 0,71073&#197; &#956 = 0,954 mm-1; F(000) = 2404; R=0,538 for 9281 independent reflections and 487 refined parameters. This triply chloro-bridged binuclear complex is formed by two Ru atoms bridged through three chloride anions. One Ru atom is further coordinated to two non-bridging Cl atoms and a triphenylphosphine ligand, whereas the other is bonded to two PPh3 ligands and to a carbon monoxide molecule. 2) 3(dppb)H2O], Mr = 651,88, crystallizes in the orthorhombic system, space group Pbca; a=14,932(1) &#197, b=18,133 (3)&#197, c=20,59(3)&#197; V=5576,0(1)&#1973; Z=8; Dcalc =1,553g/cm-3; &#955(MoK&#945) = 0,71073&#197; &#956 = 0,985 mm-1; F(000)=2648; R=0,0461 for 4892 independent reflections and 316 refined parameters. The complex is hexacoordinated. The P atoms are in cis position to each other, forming a octhaedrical structure. This structure shows an intermolecular interaction between one Cl atom from one complex and a water hydrogen of a neighboring complex in the lattice, with Cl...H distance of 2,48(2)A. 3)[FeC19H1919N19S19], Mr=377,28, crystallizes in the monoclinic system, space group P21/n; a=11,715(2)&#197, b=7,830(2)&#197, c=18,728(3)&#197; &#946=91,570(1)&#176; V=1717,1(6)&#1973; Z=4; Dcalc =1,459g/cm-3; &#955(MoK&#945) = 0,71073&#197; &#956 = 1,004 mm-1; F(000)=784; R=0,0453 for 3018 indepen dent reflections and 218 refined parameters. This complex shows a decacoordinated Fe atom in one end of the molecule and an aromatic ring in the other, showing that the gereric radicals in Section (2.5) are R\'= CH3, X=Sl and R\" =phenyl. 4)[pyH][RuCl4(dmso)(py)].(CH2Cl2)1/2, Mr=562,11, crystallizes in the triclinic system, space group P1; a= 7,7608(1)&#197, b=85451(1)&#197, c=15,095(5)&#197; &#945=88,27(2)&#186; &#946=79,33(2)&#186; &#947,=88,77(1)&#186; V=983,2(4)&#1973; Z=2; Dcalç=1,899gcm-3; &#955(CuK&#945)=1,54184 &#197; &#956=15,001 mm-1; F(000)=556; R=0,0886 for 2909 independent reflections and 204 refined parameters. The Ru ion is octahedrally coordinated to four co-planar chloride atoms and to the nitrogen of the pyridine ring, which are trans to each other. Another protonated pyridine group, which forms the counter-cation complete the crystal struet ure. 5)[RuCl2(CO)2(AsPh3)2, Mr =840,43, crystalizes in the monoclinic system, space group P21/n; a=710,520(4)&#197, b=25,823(5)&#197, c=12,780(2)&#197; &#946=100,7401(1)&#176; V=3411,0(1)&#1973; Z=4; Dcalc =1,637gcm-3; &#955(CuK&#945)=1,54184 &#197; &#956=7,576 mm-1; F(000)=1672; R=0,0739 for 4284 independent reflections and 406 refined parameters. This complex shows a Ru atom bonded to two Cl atoms and to two CO molecules, which aproximatelly form a plane between then. The CO\'s are trans to the chlorides and the Ru further presents a coordination to two PPh3. 6) [Ru2ClBr4(CO)(AsPh3).CH2Cl2)<, Mr=154,88, crystallizes in the monoclinic system, space group P21/c; com a=14,766(2)&#197, b=18,519(2)&#197, c=20,730(4)&#197; &#946=100,085(1)&#176; V=5581,2(1)&#1973; Dcalc =1,839gcm-3; &#955(CuK&#945)=1,54184 &#197; &#956=10,947mm-1; F (000)=3004; R=0,0955 for 5738 independent reflections and 493 refined parameters. This complex is formed by two Ru atoms bridged by three Br anions. One Ru atom is further coordenated to a Br atom, to a CI atom and to a triphenylphosphine ligand, whereas the other is bonded to two AsPh3 and to a carbon monoxide molecule. In chapter 3, conclusions and future plans are given.

A bothropstoxina I (BthTX-I) é uma miotoxina isolada do veneno da serpente brasileira Bothrops jararacussu, a qual é um membro da família das fosfolipases A2, mas não apresentam atividade catalítica devido á substituição D49K. A proteína for fornecida pelo Prof. Dr. J. R. Giglio e Profa. Dra. A. C. O. Cintra do Departamento de Bioquímica da Faculdade de Medicina de Ribeirão Preto e usada em experimentos de cristalização, os quais foram realizados usando a técnica de difusão de vapor \"hanging drop\" a 18°C. A BthTX-I cristalizou em tampão HEPES 0.1 M, pH variando entre 7.0 e 7.6. O agente precipitante foi o (NH4)SO4 em concentrações que variaram de 57% a 62% de saturação. A coleta de dados foi inicialmente feita utilizando o difratômetro automático R-AXIS IIC da Rigaku Co. do Laboratório de Cristalografia de proteínas do IFSC-USP. Subseqüentemente foi realizado uma segunda coleta de dados no SERC Daresbury Laboratory na Inglaterra, usando radiação síncrotron. A BthTX-I cristalizou no grupo espacial P3121 com os seguintes parâmetros de rede: a=b=57.58 ANGSTROM, c= 131.27 ANGSTROM, ALPHA=BETA=90° e GAMA=120°. O processamento de dados foi realizado com o programa MOSFLM, conduzindo a um Rmerge=6.3% e completeza de 99.6% a uma resolução de 2.1 ANGSTROM. A estrutura foi resolvida por Substituição Molecular, utilizando o programa AMoRe, onde foi utilizada como modelo inicial a estrutura da miotoxina da serpente Agkistrodon piscivorus piscivorus e refinada usando o programa XPLOR que conduziu a um fator Rfinal= 18.7% e Rfree=27.4%. A unidade assimétrica contém dois monômeros, os quais podem ser escolhidos de forma a apresentar interações similares aquelas descritas para a miotoxina II da Bothrops asper. A superfície de interface é entretanto, surpreendentemente pequena quando comparada com outras estruturas diméricas e a complementaridade é menor do que o valor esperado. Um modelo teórico para a ligação do fosfolipídeo na BthTX-I sugere que nenhuma interação direta entre a ligação ester sn-2 e a K49 deve ser esperada de forma a explicar a falta de atividade catalítica. Foi visto também, que é possível se reproduzir um dendrograma baseado na seqüência de aminoácidos, pelo uso de estruturas tridimensionais para os membros da família das PLA2 / Bothropstoxin- I (BthTX-I) is a myotoxin isolated from the Brazilian snake Bothrops jararacussu which is a member of the phospholipase A2 but presents no catalytic activity due to a D49K substitution. Protein was provided from the Departamento de Medecina de Ribeirão Preto by Prof. Dr. J. R. Giglio and Profa. Dra. A. C. O. Cintra and used in crystallization experiments which were performed using the vapor diffusion technique in hanging drops at 18°C. The BthTX-I crystallized in 0.1 M HEPES, pH ranging from 7.0 to 7.6. The precipitant was (NH4)SO4 in concentrations ranging from 57% to 62%. The data collection was initially performed using the automatic difractometer R-AXIS IIC from the Rigaku Co. at the Laboratório de Cristalografia of IFSC-USP. Subsequently a second data set was collected at SERC Daresbury Laboratory in England using synchrotron radiation. BthTX-I crystallizes in space group P3121 with a=b=57.58 ANGSTROM, c= 131.27 ANGSTROM, ALPHA=BETA=90° e GAMA=120°. Processing of the data was performed with the MOSFLM program yielding an Rmerge= 6.3% and completeness of 99.6% at 2.1 ANGSTROM. resolution. The structure was solved by Molecular Replacement using the package AMoRe with the Agkistrodon piscivorus piscivorus enzyme as search model and refined using the refinement program X-PLOR to a Rfinal= 18.7% and Rfree=27.4%. The asymmetric unit contains two BthTX-I monomers, which can be chosen such that they present similar interactions to those described for the homologous myotoxin II from Bothrops asper. The interface is, however, surprisingly small when compared to other dimeric structures and is less complementary than expected. A theorical model for phospholipid building to BthTX-I suggests that no direct interactions between the sn-2 ester bond and K49 would be expected, thus explaining the lack of catalytic activity. It is shown that it is possible to reproduce a dendrogram based on amino acid sequences and by the use of three dimensional structures for members of the PLA2 family

Foram realizados estudos da síntese e do crescimento de cristais de BaY2F8:TR (TR= Nd3+; Pr3+; Er3+; Tb3+; Dy3+) simplesmente dopados e codopados (Nd3+:Dy3+ ; Nd3+:Pr3+) por meio do método de fusão por zona (FZ). Os cristais crescidos foram caracterizados quanto a sua estrutura por Difração de raios-x (DRX) e Difração de nêutrons (DN) com análise pelo método de Rietveld. Foi também estudado o comportamento na fusão deste material puro e dopado com elementos terras raras trivalentes através de: microscopia eletrônica de varredura (MEV) e espectroscopia dispersiva de raios-x (EDS). A concentração final de dopantes, bem como, sua distribuição nos cristais crescidos foi estimada e, quando possível, foi ainda calculado o coeficiente de segregação de cada dopante nesta matriz. Os cristais foram também analisados por espectroscopia de absorção e emissão no caso dos materiais duplamente dopados, sendo observada evidencias de transferência de energia Nd-Pr na região UV. Foram obtidos cristais com dimensões da ordem de 40 mm x 10mm com boa qualidade óptica e estrutural adequados para estudos espectroscópicos e testes de ação laser com bombeamento por laser de diodo. Experiências preliminares de crescimento de fibras monocristalinas desta matriz pura e dopada com Tb3+, pelo método de crescimento de micro-pulling down, foram também realizadas visando uma avaliação do método aplicado a este fluoreto. Foram obtidas apenas fibras translúcidas com diâmetro constante sendo necessária maior investigação sobre o crescimento de fibras deste material puro ou dopado. / Synthesis and Growth process of single crystals of BaY2F8:TR (TR= Nd3+; Pr3+; Er3+; Tb3+;Dy3+) single-doped and co-doped (Nd3+ :Dy3+ ; Nd3+:Pr3+) were performed by Zone Melting method (ZM). The grown crystals were characterized by X-ray diffraction (XRD) and Neutron Diffraction (ND) and analyzed by the Rietveld Method. The melting behavior of this pure and trivalent rare earth doped-fluoride was investigated also by scanning electron microscopy (MEV) and X-ray energy dispersive spectroscopy (EDS). The concentration and distribution of the dopants in the grown crystals were measured, and when feasible, the segregation coefficient was estimated. The single crystals were also analyzed by absorption spectroscopy and emission spectroscopy in the case of the co-doped crystals. Evidences of the occurrence of energy transfer process in the UV for Nd-Pr were detected. From the study of the growth process single crystals of 40mm x 10mm in size, with good optical and structural quality were obtained for spectroscopy studies and tests of laser emission. Initial experiments were also performed in the growth of single crystalline fibers of this host doped with Tb3+, by the micro-pulling down method aiming a preliminary evaluation of the use of this growth process. Only semi-transparent fibers were obtained. Additional studies are necessary to improve the growth of single crystalline fibers of this fluoride.