Low temperature sintering has become a very important research area in ceramics processing and sintering as a promising process to obtain grain size below 100nm. For electronic ceramics, low temperature sintering is particularly difficult, because not only the required microstructure but also the desired electronic properties should be obtained. In this dissertation, the effect of liquid sintering aids and particle size (micrometer and nanometer) on sintering temperature and Positive Temperature Coefficient Resistivity (PTCR) property are investigated for Ba1-xSrxTiO3 (BST) doped with 0.2-0.3mol% Sb3+ (x = 0.1,0.2,0.3,0.4 and 0.5). Different sintering aids with low melting point are used as sintering aids to decrease the sintering temperature for micrometer size BST particles. Micrometer size and nanometer size Ba1-xSrxTiO3 (BST) particles are used to demonstrate the particle size effect on the sintering temperature for semiconducting BST. To reduce the sintering temperature, three processes are developed, i.e. 1 using sol-gel nanometer size Sb3+ doped powders with a sintering aid; 2 using micrometer size powders plus a sintering aid; and 3 using nanometer size Sb3+ doped powders with sintering aids. Grain size effect on PTCR characteristics is investigated through comparison between micrometer size powder sintered pellets and nanometer size powder sintered pellets. The former has lower resistivity at temperatures below the Curie temperature (Tc) and high resistivity at temperatures above the Curie temperature (Tc) along with higher ñmax/ñmin ratio (ñmax is the highest resistivity at temperatures above Tc, ñmin is the lowest resistivity at temperatures below Tc), whereas the latter has both higher ñmax and ñmin. Also, ñmax/ñmin is smaller than that of pellets with larger grain size. The reason is that the solid with small grain size has more grain boundaries than the solid with large grain size. The contribution z at room temperature and high temperature and a lower ñmax/ñmin ratio value.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22652号 / 工博第4736号 / 新制||工||1740(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 小池 克明, 教授 米田 稔, 准教授 柏谷 公希 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Orientador: Joni Augusto Cirelli / Resumo: Tratamentos de superfície, desenvolvimento de novas ligas e funcionalização das superfícies dos implantes com elementos bioativos têm sido objetivos de estudos recentes na área da Odontologia visando contribuir para o processo de osseointegração. Nesse trabalho, dois estudos investigaram a influência na resposta celular in vitro e de propriedades físico-químicas de ligas de Ti-15Mo submetidas a (1) funcionalização com estrôncio pelo método hidrotérmico previamente submetidas ou não ao tratamento químico por ácido (H3PO4) e base (NaOH) e a (2) dois métodos de aplicação de estrôncio método hidrotermal e método magnetron co-sputtering. Testes de composição química e topografia demonstraram que ambas as técnicas foram efetivas na aplicação de estrôncio. Em (1) o método hidrotermal conciliado a tratamento prévio com ácido e base apresentou resultados de maior quantificação de estrôncio com liberação mais lenta além de melhores resultados nas análises de molhabilidade, energia de superfície e resistência a corrosão. Os ensaios biológicos verificaram que em (1) células pré-osteoblásticas MC3T3-E1 apresentaram características morfológicas de maior espraiamento e proliferação em superfícies com adição de estrôncio. Em (2) células humanas do ligamento periodontal os resultados demonstraram maior proliferação e espraiamento em superfícies tratadas pelo método magnetron co-sputtering. Os estudos demonstraram que a adição de estrôncio contribuiu para os eventos celulares e, conciliadas co... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Surface treatments, development of new alloys and functionalization of implant surfaces with bioactive elements have been the objectives of recent studies in the field of Dentistry aimed at contributing to the process of osseointegration. In this dissertation, two studies investigated the influence on the in vitro cellular response and physical-chemical properties of Ti-15Mo alloys submitted to (1) strontium functionalization by the hydrothermal method previously submitted or not to chemical treatment with acid (H3PO4) and alkali (NaOH) and (2) two methods of strontium application: hydrothermal method and magnetron co-sputtering method. Tests of chemical composition and topography demonstrated that both techniques were effective in the application of strontium. In (1) the hydrothermal method reconciled the previous treatment with acid and alkali presented results of greater strontium quantification with slower release and better results in the analysis of wettability, surface energy and corrosion resistance. The biological tests verified that in (1) preosteoblastic cells MC3T3-E1 presented morphological characteristics of greater spreading and proliferation on surfaces with strontium addition. In (2) human periodontal ligament cells the results showed greater proliferation and spreading on surfaces treated by the magnetron co-sputtering method. The studies demonstrated that the addition of strontium contributed to cellular events and, combined with chemical treatment prior to... (Complete abstract click electronic access below) / Mestre

Orientador: Rosemary Adriana Chierici Marcantonio / Resumo: O objetivo desse trabalho foi avaliar o efeito preventivo da administração do Ranelato de Estrôncio sobre o processo de osteonecrose induzida por bisfosfonatos. Serão utilizados 60 ratos, divididos randomicamente em 6 grupos de acordo com os diferentes protocolos de administração dos medicamentos: Grupo CTR - Foi administrado soro fisiológico por injeção subcutânea diariamente por 60 dias, em seguida foi realizada uma cirurgia para extração dos primeiros molares inferiores, e posteriormente foi continuada a aplicação diária de soro por mais 30 dias; Grupo ALN -Foi administrado alendronato de sódio (1 mg/kg/dia) por via subcutânea durante 60 dias antes da extração dos primeiros molares inferiores e a mesma foi continuada por 30 dias após o procedimento cirúrgico; Grupo ALN/S - O alendronato foi administrado por 60 dias e após esse período foi feita a extração. Posteriormente, os animais receberam soro fisiológico por 30 dias; Grupo ALN/Sr - Foi administrado alendronato durante 60 dias e posteriormente foi interrompida a sua administração por 30 dias previamente a extração. Em seguida a extração, foi administrado o ranelato de estrôncio por 30 dias (625 mg/kg/dia) por gavagem; Grupo ALN /S60- O alendronato foi administrado durante 60 dias e tiveram sua administração interrompida por 30 dias até o momento da extração. Posteriormente a extração foi administrado soro por mais 30 dias após a cirurgia.; Grupo ALN/Sr 60 - Foi administrado alendronato por 60 dias, e após esse período ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study will be to evaluate the preventive effect on the administration of the Strontium Ranelate over the process of osteonecrosis induced by bisphosphonate. Sixty rats will allocate in 6 groups according to the different protocols of the medications administration: CTR- It will be apply daily a saline solution by subcutaneous injection for 60 days, then, a surgery will be made to remove the inferior molars and posteriorly the daily application of saline solution will be continued for 30 more days; ALN - administration of sodium alendronate (1mg/kg/day) by subcutaneous injection for 60 days before de extraction of the first inferior molars. The injections of sodium alendronate will continue for 30 days after the surgical procedure; ALN/S - Alendronate will be applying for 60 days and then, the extraction will be made. After that, the animals will receive saline solution for 30 days by daily injection; ALN/S60 - Alendronate will be apply for 60 days and then, the administration will be interrupted for 30 days before the surgery. A saline solution will be apply for 30 days after the tooth extractions; ALN/Sr Group - Alendronate will be apply for 60 days and posteriorly the administration will be interrupted for 30 days, before the extraction. After this, Strontium Ranelate will be apply for 30 days (625mg/kg/day) by gavage; ALN/Sr 60 Group - Alendronate will be apply for 60 days, and after that, this administration will be interrupted and the strontium ranelate w... (Complete abstract click electronic access below) / Mestre

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21004号 / 医博第4350号 / 新制||医||1028(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 戸口田 淳也, 教授 妻木 範行, 教授 開 祐司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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Insect migration stands as a phenomenon of paramount ecological importance, influencing ecosystems through a myriad of mechanisms, from facilitating pollination to aiding at disease transmission. Many insect species undertake multi-generational migrations in the Afro-tropical and Palearctic ranges, and increasing evidence highlights a number of migratory circuits across the entire Afro-Palearctic. Yet unravelling the migratory connectivity of the successive generations of these insects remains challenging given the impossibility to apply traditional biologger technology (e.g., radiotelemetry, light loggers), because of the small size, short life span and often large population sizes and ranges of insects. To address this challenge, this research pioneers the application of dual stable isotopic geolocation techniques based on hydrogen (δ2H) and strontium (⁸⁷Sr/⁸⁶Sr). Isotope geolocation consists of comparing the isotopic signatures of a mobile individual (e.g., migratory insect) to a map predicting isotope variations on the landscape (i.e., isoscape). Consequently, applying isotope geolocation to reconstruct insect migratory routes and connectivity requires the development of isoscapes across the migratory circuit. We first developed a novel δ2H isoscape in insect wing tissues across the Afro-Palearctic range. We analyzed wing tissue from resident butterflies across the Afro-Palearctic. A strong linear relationship between δ2H in local known-origin butterfly wings and local growing-season precipitation δ2H values was found across the Afro-Palearctic allowing the development of a robust isoscape. However, the relationship was weaker in the Afrotropics due to the region’s unique environmental characteristics, notably highly variable evaporation rates and relative humidity. Achieving increased geolocation precision in this region will necessitate the development of novel modeling approaches, incorporating more time-specific environmental and climate data as well as combining other independent geolocation tools. To enhance the isotope geolocation potential of migratory butterflies across the Afro-Palearctic range, we developed a bioavailable strontium isoscape. Strontium isotope variations on the landscape are usually independent from those of hydrogen providing a second level of geolocation evidence and enhancing geolocation potential. To build a ⁸⁷Sr/⁸⁶Sr isoscape, we first compiled bioavailable ⁸⁷Sr/⁸⁶Sr data across the range and analyzed a series of plant samples to fill existing spatial gaps. We then applied a novel spatial interpolation ensemble machine learning approach to predict bioavailable ⁸⁷Sr/⁸⁶Sr ratios across the range. Our analysis emphasizes the influence of factors such as geology, lithology, soil properties but also desert dust and volcanic aerosol deposition on bioavailable ⁸⁷Sr/⁸⁶Sr. The novel ensemble machine learning approach outperforms the traditional random forest regression approach and provides a better assessment of spatial uncertainty to produce the most accurate and unbiased bioavailable ⁸⁷Sr/⁸⁶Sr isoscape across the Afro-Palearctic range. As a first test to demonstrate the potential of this dual δ2H-⁸⁷Sr/⁸⁶Sr geolocation approach, we applied it to study the migratory routes and connectivity of Vanessa cardui individuals collected from each side of the Sahara Desert. Dual isotope-based metrics elucidated painted lady migration across the Sahara in unprecedented detail, notably moderate population connectivity across the Sahara with dominance of latitudinal migratory trajectories, a leapfrog migration during the southern leg across the Sahara, and incremental shorter distance migration during the northern leg of the migratory cycle. The study also highlighted the important role of the Arabian Peninsula as a significant stepping-stone for individuals traveling between Europe, Africa, and Asia. Such patterns and knowledge of this species' connectivity level will help conservation practitioners better assess risks and improve conservation strategies. In conclusion, this thesis presents two novel isoscapes, each with a range of applications. The δ2H isoscape is applicable to trace regional dispersal or migration of insects across the Palearctic, including both bidirectional migration and one-way dispersive behavior. The ⁸⁷Sr/⁸⁶Sr isoscape provides a basis to study mobility across the African continent and is applicable not only to trace the mobility of terrestrial insects but also the origin of other animals, humans, and manufactured materials across Africa. Together those isoscapes considerably advance the possibility of reconstructing the mobility of migratory insects to solve novel questions as evidenced by our case study on painted ladies.