As cerâmicas porosas empregadas na substituição óssea, são utilizadas por apresentarem características como biocompatibilidade, ter estrutura tridimensional e apresentar alta porosidade. Nesse sentido, o objetivo desse trabalho foi obter e caracterizar cerâmicas porosas de Al2O3 e Al2O3 contendo 5% em volume de inclusões de ZrO2, produzidas pelo método da réplica. Essas cerâmicas porosas tiveram sua superfície tratada quimicamente com ácido fosfórico e foram recobertos, com fosfato de cálcio usando o método biomimético, em solução de SBF 5X (Simulated Body Fluid) por um período de incubação de 14 dias. Após o recobrimento, algumas cerâmicas porosas foram tratadas quimicamente para incorporação do Sr2+. Em seguida foram caracterizadas morfologicamente e estruturalmente usando ensaios de compressão axial, porosidade aparente, microscopia eletrônica de varredura (MEV), microtomografia de Raio X (µ-CT), difratometria de Raio X (DRX), Espectroscopia de Infravermelho Próximo (NIR), emissão óptica com plasma indutivamente acoplado (ICP-OES), Energia Dispersiva de Raio-X (EDS) e por Ensaios biológicos utilizando cultura de células para análise de viabilidade celular. As cerâmicas porosas de alumina e alumina-zircônia apresentaram, respectivamente, porosidade aparente de 80,93 % e 78,82 %, resistência à compressão axial, 2,93 MPa e 6,59 MPa, além de uma ampla faixa de tamanho de poros de, desejáveis para o favorecimento de interesses biológicos destinados à regeneração e formação de tecido ósseo. O recobrimento biomimético usando SBF 5X produziu a formação das fases α-TCP, β-TCP, TTCP e Hidroxiapatita, usando período de incubação de 14 dias. A incorporação de Sr2+ na estrutura dos fosfatos mostrou-se mais eficientes nos corpos porosos de alumina-zircônia. Os ensaios in vitro mostraram a biocompatibilidade das cerâmicas porosas estudadas, demonstrando a possibilidade de sua utilização como material para substituição ou preenchimento ósseo. / The porous ceramics used in bone substitution are used because they present characteristics as biocompatibility, have a three - dimensional structure and have high porosity. In this sense, the objective of this work was to obtain and characterize porous ceramics of Al2O3 and Al2O3 containing 5% by volume of ZrO2 inclusions, produced by the replica method. These porous ceramics were chemically treated with phosphoric acid and were coated with calcium phosphate using the biomimetic method in 5X SBF solution (Simulated Body Fluid) for a 14 day incubation period. After coating, some porous ceramics were chemically treated for Sr2+ incorporation. They were then characterized morphologically and structurally using axial compression, apparent porosity, scanning electron microscopy (SEM), microtomography (µ-CT), X-ray diffractometry (XRD), Near Infrared (NIR) Coupled (ICP-OES), X-ray Dispersive Energy (EDS) and Biological Assays using cell culture for cell viability analysis. The porous ceramics of alumina and alumina-zirconia showed, respectively, 80.93% and 78.82% apparent porosity, axial compression strength, 2.93 MPa and 6.59 MPa, as well as a wide range of pore size, desirable for the promotion of biological interests destined to the regeneration and formation of bone tissue. Biomimetic coated using SBF 5X produced the formation of α-TCP, β-TCP, TTCP and Hydroxyapatite phases using a 14-day incubation period. The incorporation of Sr2+ in the phosphate structure proved to be more efficient in porous alumina-zirconia bodies. The in vitro tests showed the biocompatibility of the porous ceramics studied, demonstrating the possibility of their use as material for bone replacement or filling.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-05-05T13:56:21Z No. of bitstreams: 1 gabrielpinheirolacerda.pdf: 1840814 bytes, checksum: 711c6aedc66cee4634cf4c1d2a8d1317 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-06-07T15:38:01Z (GMT) No. of bitstreams: 1 gabrielpinheirolacerda.pdf: 1840814 bytes, checksum: 711c6aedc66cee4634cf4c1d2a8d1317 (MD5) / Made available in DSpace on 2016-06-07T15:38:01Z (GMT). No. of bitstreams: 1 gabrielpinheirolacerda.pdf: 1840814 bytes, checksum: 711c6aedc66cee4634cf4c1d2a8d1317 (MD5) Previous issue date: 2015-04-27 / O propósito deste estudo foi avaliar in vitro, a resistência de união entre os constituintes dos pilares híbridos de zircônia, comparando diferentes tipos de cimentos resinosos. Para a realização do presente estudo foram confeccionadas trinta peças de zircônia com formato anatômico de primeiro molar inferior direito. Estas foram divididas em três grupos de acordo com os cimentos resinosos a serem utilizados para cimentá-las sobre bases metálicas de titânio: Grupo A- cimento auto adesivo de dupla ativação, Grupo B- cimento de dupla ativação convencional e Grupo C- cimento quimicamente ativado. Posteriormente ao processo de cimentação, os 30 corpos de prova foram armazenados em água destilada por 24 horas em temperatura ambiente e em seguida, foram submetidos à ciclagem térmica em equipamento específico sendo submetidos a banhos em 5o C e 55o C, com 30 segundos de permanência em cada banho, tempo de deslocamento de 2 segundos, totalizando 6.000 ciclos. Os testes de ciclagem mecânica foram realizados com os corpos de prova imersos em água destilada a 37o C, com carga de 100N, frequência de 2Hz e 200.000 ciclos. Após os testes termomecânicos, os espécimes foram submetidos a testes de tração na máquina de ensaio universal EMIC DL 2000. Os valores de resistência de união foram obtidos em Quilograma Força (Kgf) para cada espécime. Os dados obtidos pelo ensaio de tração foram submetidos ao teste ANOVA, com nível de significância de 5%. Anterior a realização deste teste, os dados foram verificados quanto a sua normalidade e homocedasticidade pelos testes de Shapiro-Wilk e Bartlett, respectivamente. Por meio de um estereomicroscópio verificou-se que o modo de falha de cimentação do tipo adesiva, entre cimento resinoso e superfície de zircônia, ocorreu em todos os corpos de provas. Conclui-se que os diferentes tipos de cimentos resinosos testados neste estudo se comportaram de maneira eficiente na cimentação das duas peças dos pilares híbridos de zircônia. / Objective: The purpose of this study was to evaluate in vitro by means of tensile test, the bond strength of the constituents of zirconia abutments of two pieces in unit restorations on implants with prosthetic connections cone morse type, comparing three different types of cements resinous. Materials and Methods: Thirty zirconia pieces with the mandibular first molar format were divided into three groups according to the cement to be used to cement them on metal titanium bases: Group A- Relyx U200, Group B- Panavia F 2.0 and Group C- Multilink. Subsequently the process of cementing, the 30 specimens were stored in distilled water for 24 hours at room temperature and then were submited to thermal cycling in specific equipment undergoing baths in 5°C and 55°C, with 30 seconds remaining in each bath, 2 seconds travel time, totaling 6.000 cycles. The mechanical cycling tests were performed with the samples immersed in distilled water at 37°C, with 100N load, frequency of 2Hz and 200.000 cycles. After the thermomechanical tests, the specimens were subjected to tensile tests in a universal testing machine EMIC DL 2000. The bond strength values were supplied by the computer of the testing machine, and obtained in kilogram force (Kgf) individually for each specimen. The data obtained hair tensile test were submitted when ANOVA test, with significance level of 5 %. Previous conducting this test, the were data are checked for normality and homocedasticity those testicles - Wilk Shapiro and Bartlett, respectivamente. By means of hum stereomicroscope has been found that the adhesive cementation failure mode to type, resin cement and surface zirconia occurred in all the evidence of bodies. It is concluded that the three types of resin cements tested in this study behaved way efficient cementation of two parts of hybrid pillars of zirconia.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study in vitro proposed to evaluate the influence of silica-based film coated on the Y-TZP surface on the durability bond strength (BS) between ceramic and resin cement. Eighty Y-TZP blocks (5x5x4 mm) were obtained, included in acrylic resin and were divided into four groups according to the surface treatments treatments (n=20): (TBS) tribochemical silica coating (Cojet, 3M/ESPE), (F-5) 5 nm SiO2 nanofilm and silanization, (F-500) 500 nm SiO2 nanofilm and silanization, and (F-500HF) 500 nm SiO2 nanofilm + HF + silanization. Specimen of composite resin were made with a metal matrix and cemented with resin cement (Relyx ARC) to Y-TZP blocks. Half of the specimens (n=10) of each treatment was tested 24 hours after adhesion (dry), and another half (n=10) will be subjected to the aging (storage for 90 days and 103 thermal cycles). The specimens were submitted to shear test (1min/min). After debonding, the surfaces will be analyzed by optical microscopy and scanning electron microscopy (SEM) to categorize the failure modes and the micro morphology of treated surfaces. Additional analyzes were made in X-ray dispersive energy analysis (EDS). Data were statistically analyzed for Kruskal-Wallis/Mann Whitney (α=0,05) tests. The surface treatment showed significant differences in conditions D (p=0.0001) and A (p=0.0000). In both test conditions , TBS and F-5 promoted the highest bond strength, significantly. Means (SD) for BS data (MPa) were: TBS/D: 10.2 (5.1)AB; F-5/D: 12.0 (3.9)A; F-500/D: 14.9 (4.7)A; F-500HF/D: 4.1 (5.6)B; TBS/A: 9.1 (4.4)a; F-5/A: 7.8 (5.3)a; F-500/A: 0.01 (0.0)b; F-500HF/A: 1.4 (2.3)b. The adhesion to zirconia can be improved if the surface receives a 5 nm layer of SiO2 nanofilm or is subjected to sandblasting with silica particles, followed by silanization. / O presente trabalho avaliou, in vitro, a influência da deposição de filmes à base de sílica sobre a superfície da Y-TZP na durabilidade da resistência de união entre essa cerâmica e um cimento resinoso. Foram confeccionados oitenta blocos (5x5x4 mm) de Y-TZP, estes foram incluídos em resina acrílica e divididos em 4 grupos de acordo com o tratamento de superfície (n=20): (TBS) tratamento triboquímico (Cojet, 3M/ESPE); (F-5) filme de SiO2 de 5 nm e silanização; (F-500) filme de SiO2 de 500 nm e silanização; (F-500HF) filme de SiO2 de 500 nm + HF + silanização. Sobre os blocos de Y-TZP foram cimentados (RelyX ARC) cilindros feitos com resina composta confeccionados com uma matriz metálica. Metade dos espécimes (n=10) de cada grupo foi testada após 24h de cimentação (S- sem envelhecimento) e a outra metade (n=10) foi submetida ao envelhecimento (TC, armazenagem por 90 dias e 103 ciclos térmicos). Então, os espécimes foram submetidos ao teste de cisalhamento (1min/min). Após o teste, as superfícies foram analisadas por Microscópio Óptico e MEV para categorizar o modo de falha. Também foram feitas análises adicionais em EDS. Os dados foram analisados estatisticamente pelo teste de Kruskal-Wallis/Mann Whitney (α=0,05). A resistência adesiva foi influencida pelo tipo de tratamento de superfície, nas condições S (p=0.0001) e TC (p=0.0000). Em ambas condições de armazenagem, os tratamentos TBS e F-5 promoveram mais alta resistência adesiva, significativamente. Médias (DP) de RU (MPa) foram: TBS/S: 10,2(5,1)AB; F-5/S: 12,0(3,9)A; F-500/S: 14,9(4,7)A; F-500HF/S: 4,1(5,6)B; TBS/TC: 9,1(4,4)a; F-5/TC: 7,8(5,3)a; F-500/TC: 0,01(0,0)b; F-500HF/TC: 1,4(2,3)b. Concluiu-se que a adesão a zircônia pode ser potencializada se a superfície receber a deposição do filme de SiO2 de 5 nm ou for submetida a jateamento com partículas de sílica, seguida de silanização.

Abstract The aim of the thesis was to find new information on the effect of BaO and oxygen storage capacity material on NOx reduction. A total of nine different kinds of Pd/Al2O3-based metallic monoliths were studied. Promoters such as oxygen storage capacity material (OSC material in our case Cex-1ZrxO2 mixed oxides) and stabilisers such as barium (BaO) were added into the catalyst alone or together to improve catalyst properties such as catalytic activity, selectivity, and thermal stability. The key aspects in this thesis can be divided into four parts. First, the behaviour of NO reduction and CO as well as C2H4 oxidation over Pd/Al2O3-based catalysts in rich, stoichiometric and lean conditions were studied. Secondly, the effect of BaO and the OSC material in NO reduction was considered. Thirdly, the preparation procedure, i.e. the addition order of BaO, OSC material, and Pd on the catalyst was considered. Finally, the effect of ageing on the behaviour of catalysts was investigated. Several characterization methods (in situ DRIFT, catalytic activity measurements, N2 physisorption, CO chemisorption, dynamic oxygen storage capacity measurements, and X-ray diffraction (XRD)) were utilised to find answers to the behaviour of these catalysts in the studied model reactions. The Rapid Ageing Hot in Laboratory (RAHLAB) method was used to age the catalyst. First, it was demonstrated that the CO and hydrocarbon oxidation and NO reduction reactions over the Pd/Al2O3-based catalyst behave differently. NO reduction and CO and hydrocarbon oxidation reactions were dependent on the reaction conditions and temperatures. Secondly, the effect of OSC and BaO on NO reduction was studied separately. In the case of OSC material, it was observed that the OSC material has an effect on NO reduction as well as on CO and C2H4 oxidation. In the case of BaO, it was observed that BaO has a positive effect on NO reduction as well as CO and C2H4 oxidation especially in rich conditions. Thirdly, the effects of the addition order of OSC and BaO on the catalyst was studied separately. It was shown that these have an effect on NO reduction, especially after ageing. First, on the fresh Pd/Al2O3 catalyst it was observed that the addition order of OSC on the catalyst has not an influence on catalyst performance. The effect of the BaO addition order on the Pd/OSC/Al2O3-based catalyst is found to be insignificant, especially, after the ageing process. Furthermore, it is observed that the effect of RAHLAB ageing was that the catalyst lost its catalytic activity, stability, and selectivity.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2015-12-04T17:19:33Z No. of bitstreams: 1 monizecarellifelipeantunes.pdf: 3029600 bytes, checksum: 8f67d08272a23a5ae00bcc9865b95fc8 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2015-12-07T03:23:14Z (GMT) No. of bitstreams: 1 monizecarellifelipeantunes.pdf: 3029600 bytes, checksum: 8f67d08272a23a5ae00bcc9865b95fc8 (MD5) / Made available in DSpace on 2015-12-07T03:23:14Z (GMT). No. of bitstreams: 1 monizecarellifelipeantunes.pdf: 3029600 bytes, checksum: 8f67d08272a23a5ae00bcc9865b95fc8 (MD5) Previous issue date: 2015-03-09 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este estudo avaliou o efeito de diferentes tratamentos de superfície na resistência de união e adaptação marginal entre uma coroa de cerâmica Y-TZP e um material análogo à dentina. Foram confeccionadas 40 bases de um material resinoso análogo à dentina (NEMA grade G-10) para originar preparos padronizados. Estes foram usinados para simular um dente preparado para coroa total com término em chanfro, paredes de 6 graus de convergência e anatomia radicular. A porção radicular foi coberta com poliéter (Impregum - 3M ESPE) e incluída em poliuretano (F16 - Axson). Quarenta coroas cerâmicas IPS emax ZirCAD (Ivoclar - Vivadent) foram fabricadas pelo sistema CAD/CAM. Para o tratamento de superfície foram realizadas a silicatização, aplição de primer para zircônia e duas técnicas de vitrificação, sendo que estas representaram os grupos teste. As coroas foram aleatoriamente divididas em 4 grupos (n=10), conforme o tratamento de superfície: GS (Glaze Spray VITA AKZENT), condicionamento com ácido fluorídrico a 10% (HF) (1 min) + silanização (RelyX Ceramic Primer - 3M ESPE); GP (Glaze Pó/Líquido VITA AKZENT), condicionamento com HF a 10% (1 min) + silanização (RelyX Ceramic Primer - 3M ESPE); P: aplicação do primer (Signum Zirconia Bond - Heraeus Kulzer) e RS: jateamento com partículas de óxido de alumínio revestidas por sílica 30 μm (Rocatec Soft® 3M ESPE ) (silicatização) + silanização (RelyX Ceramic Primer - 3M ESPE). Em seguida, realizou-se a cimentação das coroas com o cimento autoadesivo Rely X U200 (3M ESPE), seguindo as recomendações do fabricante. Todas as amostras de cada grupo foram submetidas à ciclagem termomecânica (TC) (2.000.000 ciclos – 100 N, 4 Hz, 5 ºC – 55 ºC, tempo de permanência 60 s), com um pistão de aço inoxidável (Ø=4mm) no centro da superfície oclusal. Para avaliação da desadaptação marginal entre a coroa cimentada e o G-10, realizou-se a análise por estereomicroscópio (EM) (40x), fazendo-se 8 aferições para cada amostra e, por microscópio eletrônico de varredura (MEV). Para determinação da resistência a tração, foi realizado o ensaio mecânico numa máquina de ensaio universal (célula de carga de 1000 Kgf, v= 1mm/min) até o descolamento da coroa. Os dados de desadaptação marginal obtidos foram analisados estatisticamente (Teste Kruskal Wallis e de Dunn: p ˂ 0,05) e os dados de resistência de união foram analisados pelo teste Anova (um fator) e de Tukey (p ˂ 0,05). Os resultados de desadaptação marginal (média e desvio padrão) foram os seguintes GS (48,69±19,90ª μm); GP (65,48±42,57ª μm); P (156,0±113,3c μm) e RS (96,05±62,98b μm). Os resultados de resistência de união foram: GP (470,5±104,1ª μm); GS (416,8±170,2ª μm); P (342,1±109,7ab μm) e RS (208,9±110,0b μm). Através do estudo realizado concluiu-se que os grupos que tiveram menor desadaptação marginal foram GS e GP; os valores de resistência de união dos grupos GP e GS foram estatisticamente superiores aos valores de resistência de união do grupo RS e semelhante aos valores encontrados para grupo P. / This study evaluated the effect of different surface treatments on the bond strength and marginal adaptation from a Y-TZP ceramic crown and a material similar to dentin. Were made 40 bases in a similar resinous material to dentin (NEMA G-10 grade) to give standardized preparations. These were machined to simulate a tooth prepared for full crown in bevel, walls of 6 degrees of convergence and root anatomy. The root portion was covered with polyether (Impregum - 3M ESPE) and included in polyurethane (F16 - Axson). Forty crowns IPS emax ZirCAD (Ivoclar - Vivadent) were fabricated by CAD / CAM system. For the surface treatment were carried out silica coating, application of primer to zirconia and two glazing techniques, and these test groups represented. The crowns were randomly divided into 4 groups (n = 10), as the surface treatment: GS (VITA Akzent Glaze Spray), etching with hydrofluoric acid 10% (HF) (1 min) + silanization (RelyX Ceramic Primer - 3M ESPE ); GP (Glaze Powder / Liquid VITA Akzent), etching with HF 10% (1 min) + silanization (RelyX Ceramic Primer - 3M ESPE); P: primer (Signum Zirconia Bond - Heraeus Kulzer) and RS: sandblasting with aluminum oxide particles coated with silica 30 microns (Rocatec SOFT® 3M ESPE) (silica coating) + silanization (RelyX Ceramic Primer - 3M ESPE). Then was held the cementation of crowns with the self-adhesive cement Rely XU200 (3M ESPE), following the manufacturer's recommendations. All samples from each group were submitted to thermomechanical cycling (TC) (2,000,000 cycles - 100 N, 4 Hz, 5° C - 55° C, residence time 60 sec) with a stainless steel piston (= Ø 4mm) the center of the occlusal surface. Then the analysis by stereomicroscope (MS) (40x) and scanning electron microscope (SEM) to evaluate the marginal leakage between the cemented crown and the G-10 was held. To determine the tensile strength, the mechanical test was performed in a universal testing machine (load cell of 1000 kgf, v = 1 mm / min) until the detachment of the crown. Data marginal misfit obtained were analyzed statistically (Kruskal Wallis and Dunn: p ˂ 0.05) and bond strength data were analyzed by ANOVA (one factor) and Tukey (p ˂ 0.05). The results of marginal leakage (mean and standard deviation) were as follows GS (48.69 ± 19,90ª μm); GP (65.48 ± 42,57ª μm); P (156.0 ± 113,3c μm) and RS (96.05 ± 62,98b μm). The results of bond strength were: GP (470.5 ± 104,1ª μm); GS (416.8 ± 170,2ª μm); P (342.1 ± 109,7ab μm) and RS (208.9 ± 110,0b μm). Through the conducted study showed that the groups that had less marginal discrepancy were GS and GP; values of bond strength of GP and GS groups were statistically superior to the values of bond strength of the RS group and similar to values found for group P.

Objetivo: Avaliar o desajuste vertical (gap) e discrepância horizontal (dh) na interface implante/pilares de zircônia (Zr) confeccionados por três sistemas CAD/CAM (Neodent Digital, Zirkonzahn e AmannGirrbach) e na interface implante de titânio/pilar de ZrTi confeccionado pela Neodent Digital, antes e após ciclagem mecânica. Também foi avaliada a superfície do hexágono do implante antes e após ciclagem mecânica e o destorque do parafuso do pilar pós-ciclagem. Método: Os grupos de estudo constituídos por oito amostras foram: implante/pilar de Zr AmannGirrbach (PZrAG), implante/pilar de Zr Neodent (PZrN), implante/pilar de Zr Zirkonzahn (PZrZ) e implante/pilar de Zr com infra-estrutura em Ti Neodent (PZrTiN). Pilares padronizados foram confeccionados a partir de três pilares idênticos fresados em cera, fixados sobre análogos e enviados para os laboratórios participantes do estudo. A análise da superfície, do gap e da dh foram realizadas em três amostras de cada grupo e o destorque em oito. Inicialmente, imagens da superfície dos hexágonos dos implantes foram obtidas em Microscópio Eletrônico de Varredura (MEV). Em seguida, imagens das superfícies dos pilares foram obtidas com microscópio óptico 3D (MO 3D) e posteriormente, os pilares foram acoplados aos implantes com torque de 32,0N.cm. Subsequentemente, imagens das interfaces implante/pilar foram obtidas em MEV para posterior comparação com as imagens pós-ciclagem. Coroas de CrCo foram cimentadas nos pilares e os conjuntos (implante/pilar/coroa) submetidos à ciclagem com carga de 400N, frequência de 8,0 Hz, por um milhão de ciclos. Novas imagens da interface implante/pilar foram obtidas em MEV e realizadas as medições inicial e final do gap e a avaliação da dh. Em seguida, foi mensurado o destorque. Para a avaliação da superfície dos implantes, novas imagens foram obtidas em MEV e comparadas com a situação inicial. As alterações verificadas foram classificadas segundo os escores: ausência(0), leve(1), moderada(2), intensa(3). Resultados: Para o destorque(N.cm) nos grupos de Zr, o PZrZ apresentou o maior valor médio 23,12(2,7), seguido pelo PZrAG 19,57(4,3) e PZrN 19,43(1,9). O valor aferido para o grupo PZrTiN foi 21,0(2,5). Com relação às alterações de superfície, entre os grupos de Zr, a maior alteração foi observada no PZrZ 1,39(0,99) e a menor no PZrAG 0,64(0,62). O PZrTiN apresentou o seguinte valor: 0,53(0,56). Com relação ao gap, entre os grupos de Zr, o maior valor médio foi evidenciado no PZrAG 5,19(2,07)μm e o menor no PZrN 3,21(1,47)μm. O grupo PZrTiN 1,48(1,04)μm apresentou valor inferior ao grupo PZrN. Entre os pilares de Zr, o maior valor de dh foi observado no PZrAG 49,98(9,06)μm e o menor no PZrZ 31,53(32,33)μm. O PZrTiN não apresentou dh. Conclusões: Com relação ao destorque, não foi observada diferença significativa entre os grupos de zircônia, assim como entre os grupos da Neodent (Zr e ZrTi). Entre os pilares de Zr, as maiores alterações de superfície do hexágono foram observadas no grupo PZrZ e entre os pilares fresados pela Neodent (Zr e ZrTi) no PZrN. Foi observado que as alterações de superfície mantiveram relação com a forma do hexágono fresado no pilar. Quanto ao gap, entre os pilares de Zr, não foi observada diferença significativa entre os grupos; entre os pilares da Neodent (Zr e ZrTi), antes e pós ciclagem, diferença significativa foi observada entre os dois grupos, apenas antes da ciclagem; quando avaliado o gap de cada grupo antes e após a ciclagem mecânica, só o PZrZ mostrou diferença significativa. Os grupos PZrAG e PZrZ apresentaram maiores valores de gap pré-ciclagem quando considerados por face e na situação pós-ciclagem os pilares sofreram inclinação sobre o implante. Com relação à dh, quando considerados os grupos em Zr, o menor valor médio foi verificado no PZrZ e o PZrN apresentou maior regularidade entre os quatro lados observados. Todos os pilares de Zr apresentaram discrepância horizontal, alternando graus diferentes de sobre-contorno numa mesma amostra. / Purpose: To evaluate the vertical misfit (gap) and horizontal discrepancy (dh) in the zirconium (Zr) implant-abutment interface manufactured by three CAD/CAM systems (Neodent Digital, Zirkonzahn and AmannGirrbach) and the ZrTi implant-abutment manufactured by Neodent, before and after cyclic loading. The surface of the titanium (Ti) hexagon implant was also evaluated before and after cyclic loading as well as the torque loss of the abutment screw post loading. Method: The study groups made up of 8 samples were as follows: Zr AmannGirrbach (PZrAG) implant-abutment, Zr Neodent (PZrN) implant-abutment, Zr Zirkonzhan (PZrZ) implant-abutment and Zr implant-abutment with Ti Neodent (PZrTiN) infrastructure. Standard-made abutments were manufactured from three identical abutments milled in wax, fixed on analogs and sent to the participant laboratories. The analysis of the surface, the gap and the dh were performed on three samples from each group and the torque loss was performed on eight samples. Initially, images of the surface of the hexagon implant were obtained by Scanning Electron Microscope (SEM). Then, images from the abutment surfaces were obtained from optical microscope 3D (MO 3D), followed by the tightening of the abutments to the implants with torque of 32.0N.cm. Subsequently, images of the implant-abutment interfaces were obtained from the SEM for comparison with the post loading images. CrCo crowns were cemented on the abutments and the combination (implant/abutment/crown) was submitted to cyclic loading with a load of 400N, frequency of 8.0Hz, for one million cycles. New images of the implant-abutment interface were obtained from the SEM, and initial and final gap measurements were done with evaluation of the dh. The torque loss was measured. For the evaluation of the surface of the implants, new images were obtained from the SEM and compared with the initial situation. The observed changes were classified according to the following categories: none (0), mild (1), moderate (2), intense (3). Results: In relation to the torque loss (N.cm) in the groups of Zr, the PZrZ showed the highest average of 23.12(2.7), followed by the PZrAG of 19.57(4.3) and the PZrN of 19.43(1.9). The measured value for the PZrTiN was 21.0(2.5). In regards to the surface alterations among the Zr groups, the highest change was observed in the PZrZ of 1.3 9(0.99) and the lowest change in the PZrAG of 0.64(0.62). The PZrTiN group presented the following value: 0.53(0.56). In regards to the gap among the Zr groups, the highest average value was evidenced in the PZrAG of 5.19(2.07)μm and the lowest in the PZrN of 3.21(1.47)μm. The PZrTiN group of 1.48(1.04)μm showed an inferior value compared to the PZrN group. Among the Zr abutments, the highest horizontal discrepancy value was observed in the PZrAG of 49.98(9.06) and the lowest value was observed in the PZrZ of 31.53(32.33)μm. The PZrTiN did not present dh. Conclusions: Regarding torque loss, significant differences were not observed among the zirconium groups, as well as among the Neodent groups (Zr and ZrTi). Among the Zr abutments, the largest hexagon surface alterations were observed in the PZrZ group and among the abutments milled by Neodent (Zr and ZrTi) in the PZrN. It was observed that surface changes showed that a relationship is maintained with the shape of the hexagon milled in the abutment. As to the gap among the Zr abutments, no significant difference was noted among the groups; between the Neodent abutments (Zr and ZrTi), before and after cyclic loading significant difference between the two groups was observed only before cyclic loading. When evaluated the gap of each group before and after cyclic loading, only the PZrZ showed significant difference. The groups PZrAG, and the PZrZ showed the highest pre-cycling gap when considered by face-value and in the post loading situation, the abutments suffered inclinations over the implant. As to dh when considering the Zr groups, the lowest average value was found in the PZrZ, and the PZrN showed highest regularity among the four sides observed. All Zr abutments showed horizontal discrepancy alternating different levels of over-contour in the same sample.

Objective: The goal of the present study was to investigate the effect of chairside surface treatments on biaxial flexural strength and subsurface damage of monolithic zirconia ceramics. Methods: Specimens (15x15x1.2 mm3) were prepared by sectioning from commercially available zirconia blanks (BruxZirTM) and sintering according to manufacturer's recommendations. Fully dense specimens were randomly divided into five groups (n=30) and treated as follows; 1) as-sintered (AS) 2) air abraded with 50 μm alumina fine particles (AAF), 3) air abraded with 250 μm coarse alumina particles (AAC), 4) ground (G), and 5) ground and polished (GP) to mimic chairside and dental laboratory treatments. Microstructural changes were thoroughly characterized by optical and scanning electron microscopy, surface profilometry and atomic force microscopy. Crystalline phases and their depth profile were investigated by x-ray diffraction (XRD) and grazing incidence x-ray diffraction (GIXRD). Results were analyzed by Kruskal-Wallis test and Tukey's adjustment for multiple comparisons. A 0.05 level of significance was used. Reliability was evaluated by Weibull analysis. Results: All treatment groups exhibited a significant difference in mean surface roughness (Rq) compared to the as-sintered group (p<0.05). The AAC group showed the highest surface roughness at 1.08 ± 0.17 μm, followed by the G, AAF and AS groups. The GP group exhibited the lowest surface roughness. The group air abraded with fine particles showed the highest mean biaxial flexural strength (1662.62 ± 202.58 MPa), but was not different from the ground and polished group (1567.19 ± 209.76 MPa). The groups air abraded with coarse particles or ground with diamond bur exhibited comparable mean biaxial flexural strength at 1371.37 ±147.62 MPa and 1356.98 ±196.77 MPa, respectively. The as-sintered group had the lowest mean biaxial flexural strength at 1202.29 ±141.92 MPa. The depth of compressive stress layer, measured by GIXRD was approximately 50 μm in the AAF group, followed by the AAC group with ~35 μm, ~10 μm for the ground group and ~5 μm for the ground and polished group. Deep subsurface cracks were observed in the AAC group (~80 μm in depth) and G group (~25 μm in depth), whereas shallower flaws were present in the AAF and GP groups at 10 and 3 μm, respectively. Weibull analysis represented a greater reliability in zirconia specimens treated with air abrasion groups. Conclusions: Surface treatments induced the t-m transformation in 3Y-TZP and associated development of compressive stresses to a depth that varied with the severity of the treatment performed. GIXRD revealed that AAF led to the thickest compressive stress layer, followed by AAC, G and GP. SEM revealed that subsurface damage was most severe with AAC, followed by G, AAF and GP. We propose that the flexural strength results can be explained by the difference between the depth of the compressive stress layer induced by the transformation and the depth of the subsurface flaws.

Actinides, especially plutonium (Pu) and americium (Am), are of large concern for the disposal of spent nuclear fuel (SNF). The rather long half-lives of the isotopes Pu-239, Am-241 and Am-243, are causing them to govern the radiotoxicity of SNF from about 500 to 1 million years after removal from the reactor core. Therefore, the safety of a final high-level radioactive waste (HLW) repository largely depends on the mobility of these actinide isotopes. In a worst-case scenario, where water enters a HLW repository, the dissolution of the SNF matrix may lead to the mobilization of actinides. In sub-surface environments under reducing conditions, these actinides can be expected to exist in their tetravalent or trivalent oxidation states, of which the latter one is more soluble and, thus, more mobile. Therefore, the trivalent oxidation state can be considered especially important. Following a release of these trivalent actinides, the multi-barrier concept of a final repository is designed to hinder their spreading into the environment through immobilization reactions such as adsorption to a surface or incorporation via secondary phase formation. One of the first possible interaction partners for actinides is the corrosion layer on the cladding material surrounding the fuel rods, consisting of zirconia (ZrO2). ZrO2 is capable to act as adsorber material for actinides as well as of incorporating large quantities of actinides. Furthermore, zirconia is a promising solid phase for the immobilization of certain waste streams from SNF reprocessing. Therefore, the possible interaction mechanisms between trivalent actinides and zirconia were studied in this thesis. In this work, various methods have been combined to gain comprehensive understanding of the macro scale as well as the molecular interactions taking place in the presence of zirconia. Information of macro scale phenomena in sorption and incorporation studies was obtained in batch-sorption experiments and with powder X-ray diffraction (PXRD), respectively. Luminescence spectroscopy (TRLFS, from time-resolved laser-induced fluorescence spectroscopy) was used in sorption and incorporation investigations to study molecular level interactions of trivalent elements on the surface or in the bulk of ZrO2. The incorporation studies were complemented with extended X-ray absorption fine-structure (EXAFS) spectroscopy. Most experiments were performed using Eu3+ (batch-sorption, TRLFS), or Y3+ (EXAFS) as actinide analogues. Spectroscopic sorption studies and complementary incorporation experiments were performed using the actinide Cm3+ (TRLFS). To study zirconia solid solutions, co-precipitation synthesis of M3+ doped hydrous zirconia, followed by calcination of the resulting phase was performed. A low-temperature hydrothermal synthesis procedure, adapted with the intent to simulate conditions potentially present in a HLW repository, was applied to selected Eu3+ doped ZrO2 compositions. The aim of these studies was to investigate how solid solution formation occurs under such hydrothermal conditions and to compare the incorporation behavior with that of the calcination method. Batch-sorption experiments revealed a favorable pH-dependent behavior for the retention of trivalent actinides in a HLW repository, as complete sorption of Eu3+ was achieved at a pH < 6 for low trivalent metal ion concentrations. The formation of three pH-dependent inner-sphere sorption complexes could be derived with TRLFS. Here, the spectroscopic signature of the third sorption complex differs from the other two. A very strong redshift of the Cm3+ emission peak (612.5 nm) and a long luminescence lifetime (190 ± 40 μs) allows for speculation, whether differing complexing anions, such as carbonates, could play a role or whether differing interaction processes, such as a surface layer incorporation could take place. The incorporation of trivalent cations into zirconia leads to a phase transformation from monoclinic (m) ZrO2, stable without any dopant to the stabilized tetragonal (t) and cubic (c) ZrO2 phases. At doping fractions high enough to stabilize the tetragonal or cubic phase, TRLFS revealed the presence of three differing dopant sites. The introduction of the aliovalent Eu3+ cation into the Zr4+ crystal structure results in the formation of oxygen vacancies to preserve charge neutrality in the crystal structure. Two of these dopant environments could be assigned to structurally incorporated Eu3+ with differing coordination numbers of 8 and 7, i.e. sites with zero or one oxygen vacancy in the first coordination sphere, respectively. The third Eu3+ species could be assigned to incorporation into surface or near-surface layers of zirconia. EXAFS revealed a constant environment of the host (Zr4+) and the dopant (Y3+) within the low doping range as well as within the stabilized zirconia phases. Therefore, the differing sites observed via TRLFS could not be observed here. Incorporation into t- or c-ZrO2 has shown a non-distinguishable spectroscopic behavior meaning that the dopant’s environment in t-ZrO2 and c-ZrO2 is very similar. TRLFS shows a low site symmetry of the dopant in both cases, despite of the high bulk symmetry, i.e. tetragonal or cubic. In the non-stabilized monoclinic crystal structure, Eu3+ incorporation was found to be accompanied by the formation of a secondary phase. The secondary phase is assumed to be nano clusters of the dopant’s oxide, forming inside the zirconia matrix. The hydrothermal synthesis of Eu3+ doped ZrO2 revealed a different phase composition as a function of dopant concentration than observed with the calcination method. At low dopant concentrations where the m-ZrO2 prevails after high-temperature treatment, t- and c-ZrO2 are very abundant after hydrothermal treatment. This is a result of the small crystallite size resulting from the low synthesis temperature and short synthesis time, which causes the stabilization of the tetragonal phase even without any dopant present. At higher doping fractions, phase compositions comparable to the calcination synthesis are obtained. Both, the sorption as well as the incorporation behavior of zirconia studied here show properties advantageous for the retention of trivalent actinides within the environment of a HLW repository. TRLFS studies of the sorption speciation showed the formation of inner-sphere complexes and, possibly surface layer incorporated species, which are more stable under environmental conditions than interactions based on Coulomb interactions only. The speciation of the Cm3+ sorption on zirconia was studied and thermodynamic data was derived via surface complexation modeling for the first time. The very systematic approach of studying the doping throughout a large range resulted in basic understanding of the dopant behavior in zirconia. The incorporation capabilities of actinides into the lattice was observed to be high for t- and c-ZrO2 while rather limited for m-ZrO2. Therefore, the monoclinic structure seems to be unsuitable for incorporating trivalent dopants. Under conditions potentially present in a HLW repository, i.e. hydrothermal synthesis conditions, the amount of m-ZrO2 was observed to be strongly reduced for low overall dopant concentrations. This could facilitate the incorporation of actinides into zirconia even at low concentration levels and therefore, increase its capabilities to act as a retention barrier in a HLW repository. The conclusions of this thesis are of importance in the field of nuclear waste management as they help closing gaps in the understanding of retention processes of trivalent actinides. The obtained molecular information can be built on with experiments designed to obtain reliable thermodynamic data, used in the safety analysis of a HLW repository. Furthermore, the interaction of zirconia with other actinides can be studied in a targeted manner based on the knowledge obtained in this thesis. In the field of material sciences, the molecular information obtained here is of interest as well, as zirconia is a very versatile material. This is due to its abundance of applications ranging from electrolyte material in solid oxide fuel cells to building materials.

Ce projet concerne la synthèse et caractérisation de nouveaux matériaux composites à base de nanoclusteurs de thiolates d’or Au25(SR)18 (tGNCs), supportés sur divers polymères de coordination (MOFs), ainsi que sur ZrO2. L’activité catalytique de ces matériaux a été évaluée sur la transformation de différents substrats. Les tGNCs sont des matériaux atomiquement bien définis et connus pour être actifs dans des réactions d’oxydation. Les nanoparticules de MOFs sont des matériaux pouvant servir de support pour des tGNCs avec de bonnes dispersions. Certains MOFs sont connus pour avoir des propriétés acides et peuvent être actifs en catalyse. Parmi eux, MIL-101 (Cr), UiO-66 (Zr) et ZIF-8 (Zn) on été choisis en raison de leur propriétés acides et/ou de stabilité thermique. La synergie entre les tGNCs et les MOFs a été évaluée à travers la conversion catalytique de différents substrats tels le glucose, le fructose, l’alcool benzylique et le furfural, impliquant des étapes nécessitant un caractère acide et/ou oxydant. Globalement, il n’a pas été observé d’impact de la présence d’or sur la réactivité de ces substrats, et les tendences catalytiques sont celles obtenues avec les MOFs seuls. Cela est certainement dû à la stabilité thermique non suffisante des MOFs qui prévient une calcination efficace des tNGCs. Lorsque ces clusters sont déposés sur ZrO2, il a été possible de les calciner à différentes températures pour étudier l’effet du ligand et de la taille de particules, pour des réactions d’oxydation en phase liquide. Ainsi, il a été montré par exemple que la température de calcination a un impact significatif sur le comportement catalytique de ces composites, qui ont donné de bonnes activités pour l’oxydation de l’alcool benzylique en benzaldéhyde dans le toluène et en conditions douces, et pour l’esterification oxydante du furfural en furoate de méthyle / This research project reports the synthesis and characterization of new composite materials based on Au25(SR)18 thiolate gold nanoclusters (tGNCs), supported over a range of metal organic frameworks (MOFs), and ZrO2. The synthesized composite materials were tested for catalytic transformations of various substrates. tGNCs are atomically well defined materials known to be active in oxidation reactions. MOFs nanoparticles are materials suitable for high dispersion of tGNCs. Some MOFs are known to have acidity and can be active as catalysts. Among them, MIL-101 (Cr), UiO-66 (Zr) and ZIF-8 (Zn) were chosen due to their acidic and/or thermal stability properties. The synergy between tGNCs and MOFs has been tested through catalytic conversions of different substrates like glucose, fructose, benzylalcohol and furfural, involving steps requiring acidic and oxidative features. Globally, no impact of the presence of Au clusters was observed, and the composite materials showed the same catalytic trends as those obtained with the MOFs alone. This is mainly due to the not sufficient thermal stability of the MOFs that prevents efficient calcination of the tGNCs. In contrast, when deposited on ZrO2 it was possible to calcine Au25(SG)18 nanoclusters at different temperatures to study the ligand and particle size effects in liquid phase oxidation reactions. For example, the calcination temperature had a significant impact on the catalytic behaviour of this composite materials, which showed good activity for the oxidation of benzyl alcohol into benzaldehyde in toluene under mild conditions, and of furfural oxidative esterification into methyl-2-furoate

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