III-nitride optoelectronic devices have become ubiquitous due to their ability to emit light efficiently in the blue and green spectral ranges. Specifically, III-nitride light emitting diodes (LEDs) have become widespread due to their high brightness and efficiency. However, III-nitride devices such as single photon sources are also the subject of research and are promising for various applications. In order to improve design efficient devices and improve current ones, the relationship between the structure of the constituent materials and their optical properties must be studied. The optical properties of materials are often examined by photoluminescence or cathodoluminescence, whilst traditional microscopy techniques such a transmission electron microscopy and scanning electron microscopy are used to elucidate their structure and composition. This thesis describes the use of a dual-beam focussed ion beam/scanning electron microscope (FIB/SEM) in bridging the gap between these two types of techniques and providing a platform on which to perform correlative studies between the optical and structural properties of III-nitride materials. The heteroepitaxial growth of III-nitrides has been known to produce high defect densities, which can harm device performance. We used this correlative approach to identify hexagonal defects as the source of inhomogeneous electroluminescence (EL) in LEDs. Hyperspectral EL mapping was used to show the local changes in the emission induced by the defects. Following this the FIB/SEM was used to prepare TEM samples from the apex of the defects, revealing the presence of p-doped material in the active region caused by the defect. APSYS simulations confirmed that the presence of p-doped material can enhance local EL. The deleterious effects of defects on the photoelectrochemical etching of cavities were also studied. We performed TEM analysis of an edge-defect contained in unetched material on the underside of a microdisk using FIB/SEM sample preparation methods. The roughness and morphology of microdisk and nanobeam cavities was studied using FIB-tomography (FIBT), demonstrating how the dual-beam instrument may be used to access the 3D morphology of cavities down to the resolution of the SEM and the slicing thickness of the FIB. This tomography approach was further extended with electron tomography studies of the nanobeam cavities, a technique which provided fewer issues in terms of image series alignment but also the presence of reconstruction artefacts which must be taken into account when quantitatively analysing the data. The use of correlative techniques was also used to establish the link between high Si content in an interlayer running along the length of microrods with changes in the optical emission of these rods. The combination of CL, FIB/SEM and TEM-based techniques has made it possible to gain a thorough understanding of the link between the structural and optical properties in a wide variety of III-nitride materials and devices.

abstract: Photochromic molecules, which photoisomerize between two chemically and optically distinct states, are well suited for electron and energy transfer to covalently attached chromophores. This dissertation aims to manipulate electron and energy transfer by photochromic control in a number of organic molecular systems. Herein the synthesis, characterization and function of these organic molecular systems will be described. Electron and energy transfer were quantified by the use of steady state absorbance and fluorescence, as well as time-resolved fluorescence and transient absorbance. A dithienylethene-porphrin-fullerene triad was synthesized to investigate photochromic control of photo-induced electron transfer. Control of two distinct electron transfer pathways was achieved by photochromic switching. A molecular dyad was synthesized, in which fluorescence was modulated by energy transfer by photoinduced isomerization. Also described is a triplet-triplet annihilation upconversion system that covalently attaches fluorophores to improve quantum yield. Overall these studies demonstrate complex molecular switching systems, which may lead to advancement in organic electronic applications and organic based artificial photosynthesis systems. / Dissertation/Thesis / Ph.D. Chemistry 2014

Orientador: Márcio Zaffalon Casati / Dissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-16T08:30:39Z (GMT). No. of bitstreams: 1 Pieri_AlexandraPaula_M.pdf: 2282598 bytes, checksum: 7fecd7736954b300b66152ae7095fe29 (MD5) Previous issue date: 2010 / Resumo: A topografia da superfície radicular é um fator importante para a manutenção da saúde dos tecidos periodontais, e a raspagem para remoção de biofilme promove alterações nessa superfície. O objetivo do presente estudo foi avaliar, por meio da análise rugosimétrica e em microscopia eletrônica de varredura, a rugosidade radicular provocada pela instrumentação periodontal com aparelho ultra-sônico piezoelétrico, utilizando diferentes substâncias irrigadoras, e comparar com o uso de cureta e de ultrassom magnetoestritivo. Para isso, foram selecionados 60 pré-molares humanos extraídos por motivos ortodônticos, que foram lavados em água corrente e acondicionados em recipientes com formol a 10%. Os dentes foram divididos aleatoriamente em 06 grupos experimentais (n=10 cada): Grupo 01: grupo controle, sem instrumentação; Gupo 02: instrumentados com curetas Gracey 5/6; Gupo 03: com aparelho ultra-sônico magnetoestritivo; Gupo 04: com aparelho ultra-sônico piezoelétrico associado ao fluido abrasivo; Grupo 05: com aparelho ultra-sônico piezoelétrico associado ao fluido polidor; Grupo 06: com aparelho ultra-sônico piezoelétrico associado aos fluidos abrasivo e polidor na seqüência. Após o tratamento das superfícies, foram realizadas, com Rugosímetro, três leituras paralelas e três perpendiculares ao sentido da raspagem para determinar os índices Ra e Rz de Rugosidade Superficial Média. Além disso, foram realizadas leituras com aumento de 50 e 250 vezes em Microscopia Eletrônica de Varredura (MEV). Para a avaliação estatística foi utilizada análise de variância (ANOVA) e teste Tukey, com nível de significância de 5%. Foi observado aumento da rugosidade independentemente do instrumento utilizado, ao comparar as superfícies tratadas com as do grupo controle (p<0,05). A instrumentação com o sistema piezoelétrico associado ao fluido polidor proporcionou as superfícies menos rugosas; o ultrassom magnetoestritivo produziu a maior rugosidade superficial entre os grupos estudados (p<0,05). Dentre os grupos do sistema piezoelétrico, o que utilizou o fluido abrasivo proporcionou os valores mais altos de rugosidade. O uso associado dos fluidos abrasivo e polidor foi semelhante ao uso da cureta, e produziu superfícies com rugosidade significativamente maior que a do uso do piezoelétrico com fluido polidor. Portanto, diante dos resultados obtidos, pode-se concluir que o uso das diferentes substâncias irrigadoras na instrumentação com ultrassom piezoelétrico influencia na rugosidade radicular. O fluido abrasivo incrementa a rugosidade superficial, mas ainda assim, o aparelho magnetoestritivo deixa as superfícies mais rugosas. A técnica que utilizou o ultrassom piezoelétrico com fluido polidor foi a que resultou nas superfícies menos rugosas / Abstract: The topography of the root surface is an important factor for maintaining periodontal tissues healthy, and scaling for biofilm removal promotes alterations in that surface. The aim of this study was to evaluate with rugosimeter and SEM examination, root roughness after instrumentation with a piezoelectric ultrasonic device using different irrigation substances, comparing with curettes and magnetostrictive ultrasonic device. Sixty human pre-molars that had been extracted for orthodontic reasons were washed in running water and kept in 10% formaldehyde until the experiment was carried. The teeth were randomly divided into 6 experimental groups (n=10, each): Group 01: control group, no instrumentation; Group 02: instrumentation with Gracey 5/6curettes; Group 03: instrumentation with a magnetostrictive ultrasonic device, Group 04: piezoelectric ultrasonic device associated to abrasive fluid, Group 05: piezoelectric ultrasonic device associated to polishing fluid, and Group 06: piezoelectric ultrasonic device associated to abrasive fluid followed by polishing fluid. After root surface treatments, three readings were carried with a rugosimeter, both parallel and perpendicularly to the direction of the scaling, in order to determine Ra and Rz rates of average surface roughness. In addition, readings with 50x and 250x magnification on Scanning Electron Microscope (SEM) were done. For statistical analysis, ANOVA and Tukey's test were used, with significance level at 5%. An increase in roughness was observed, regardless of the instrument used, when comparing treated surfaces to those in control group (p<0,05). Instrumentation with piezoelectric system associated to polishing fluid provided less rough surfaces; magnetostrictive device caused the highest roughness among the studied groups (p<0.05). Among the groups using piezoelectric system, the one using abrasive fluid caused the highest values in roughness. The combined use of abrasive and polishing fluids subsequently was similar to the curette, and produced surfaces with roughness significantly higher than piezoelectric system with polishing fluid. With the obtained results, it can be concluded that the use of different irrigation substances during instrumentation with piezoelectric ultrasonic device can influence on root surface roughness. The abrasive fluid increments surface roughness, but the magnetostrictive device is still less aggressive that. The technique that used piezoelectric ultrasound with polishing fluid resulted in less rough surfaces / Mestrado / Periodontia / Mestre em Clínica Odontológica

Orientadores: Jose Francisco Hofling, Mary Ann Foglio / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-16T21:12:15Z (GMT). No. of bitstreams: 1 Anibal_PaulaCristina_D.pdf: 11148957 bytes, checksum: 3ec093ddc1e8ca14d584eb167334aaee (MD5) Previous issue date: 2010 / Resumo: A diversidade de produtos naturais, por muitos anos, inspirou pesquisadores para identificar novos produtos que podem ser, eventualmente, desenvolvidos para novas terapias. Extratos obtidos Punica granatum L. (romã) tem demonstrado diversas atividades, dentre elas, efeito antimicrobiano. Nas últimas duas décadas, infecções por leveduras do gênero Candida cresceram significantemente pelo mundo inteiro, em decorrência do uso prolongado de antifúngicos, ligado ao aumento da resistência a esses fármacos. Sendo assim, pesquisas por novos componentes com ação antifúngica, os quais podem estar presentes nos compostos da P. granatum, justificam este estudo. Os extratos obtidos de diferentes partes do fruto da P. granatum foram testados através da metodologia da concentração inibitória mínima (CIM) frente a dez espécies de Candida spp. e analisados por espectrometria de massas. Foi observado, também, se os extratos produziam efeitos na morfologia e estrutura das leveduras através da microscopia eletrônica de varredura e de transmissão, respectivamente. Os resultados obtidos revelaram-se promissores, pois as cepas testadas foram sensíveis aos extratos, com CIM de 125µg/mL, causando danos em sua morfologia, como irregularidades em sua superfície e em sua parede celular, e a espectrometria de massas revelou compostos de reconhecida ação antimicrobiana, dentre eles, taninos. Esses dados indicam que os compostos da Punica granatum possuem ação antifúngica, sendo que as substâncias detectadas podem ser consideradas as principais responsáveis por essa atividade. Sendo assim, substâncias da Punica granatum apresentam capacidade antimicrobiana, sendo um campo promissor para descoberta de novos fitomedicamentos para o tratamento alternativo de doenças, abrindo caminhos para pesquisas que visem explorar de forma coerente essas substâncias, manipulando-as com segurança, eficácia e qualidade padronizados / Abstract: The diversity of natural products has inspired researchers for many years to identify novel products that could eventually be developed into therapeutics. The extracts obtained from Punica granatum L. (pomegranate) have demonstrated several activities as antimicrobial affects, among others. In the last couple decades infections by yeast genus Candida increased significantly worldwide, in consequence of abuse use of antifungal, associated with increase drug resistance. There researches for new compounds with antifungal action, which may be present at P. granatum justify this study. The extracts were obtained from different parts of P. granatum fruit and tested against ten strains of Candida spp., by minimal inhibitory concentration (MIC) methodology and analyzed by mass spectrometry. Also scan and transmission electron microscopy was employed to evaluate the extracts effects on the yeast's morphology and structures. The results obtained were promising, because the tested strains demonstrated sensibility towards the extracts, with MIC of 125µg/mL, causing damage to the morphology, as irregularities on its superfaces and cell wall. The mass spectrometry analysis showed compounds with known antimicrobial action, among them, tannins. The data indicated that compounds of Punica granatum have antifungal action and the detected substances can be considered to be involved with this activity. Therefore, P. granatum extracts presented antimicrobial capacity and is a promising source for the discovery of new therapeutic agents for alternative treatment, promoting scientist to continue studies on safety, efficiency and standard quality issues for P. granatum / Doutorado / Microbiologia e Imunologia / Doutor em Biologia Buco-Dental

Made available in DSpace on 2014-10-09T12:44:47Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:07Z (GMT). No. of bitstreams: 1 06999.pdf: 3514909 bytes, checksum: 57619a2289322ad837ce55b51c5b24ec (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Intituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo

Made available in DSpace on 2014-10-09T12:53:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:43Z (GMT). No. of bitstreams: 1 12360.pdf: 4474610 bytes, checksum: afe6b212ae16024e756b11010a52131a (MD5) / Tese (Doutoramento) / IPEN/T / Institut fur Metallkunde der Universitat Stuttgart, Alemanha

Made available in DSpace on 2014-10-09T12:52:12Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:02Z (GMT). No. of bitstreams: 0 / O polietileno de ultra alto peso molecular (UHMWPE) é um plástico de engenharia que tem várias aplicações atualmente, mormente em áreas específicas da indústria e da medicina. O UHMWPE pode ser utilizado ainda em outras aplicações: defensas portuárias; guias de corrente; revestimentos de caçambas, silos e calhas; engrenagens; buchas; guias de correias e próteses cirúrgicas. Esta gama de aplicações se deve ao fato das excelentes características técnicas que este material possui, como: alta resistência a abrasão, elevada resistência ao impacto, anti-aderência, atóxico, excelente resistência química, baixo peso específico, fácil usinagem e alta resistência a fadiga. Os tipos de polietileno de ultra alto peso molecular (UHMWPE) utilizados neste trabalho foram o UTEC 3041 e UTEC 6541 da Braskem. A reciclabilidade do UHMWPE ganhou interesse, porque a utilização desta matéria-prima na última década cresceu mais de 600%, tornando-se um dos plásticos de engenharia mais utilizados para obtenção de peças usinadas depois da poliamida. Com o crescimento na utilização deste polímero na confecção de peças para maquinários, o seu desperdício tem sido muito grande, porque o resto deste material é desprezado, geralmente não sendo reaproveitado. Este trabalho tem como objetivo reciclar o UHMWPE UTEC 3041 e estudar as propriedades deste material virgem e reciclado e comparar os resultados entre si e com o UHMWPE UTEC 6541, e com estes materiais submetidos a diferentes doses de radiação. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:24:21Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:27Z (GMT). No. of bitstreams: 1 01022.pdf: 2013876 bytes, checksum: 926d4f91ffb322f04f752913ee84577b (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Fisica, Universidade de Sao Paulo - IF/USP

Made available in DSpace on 2014-10-09T12:37:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:30Z (GMT). No. of bitstreams: 1 02032.pdf: 2356043 bytes, checksum: a593207617f1975d8e81afa9455b3bff (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Cristais únicos de pireno, C16H10, irradiados por raios X, à temperatura ambiente, foram estudados por técnicas de RPE para determinar os radicais livres formados pela radiação. A dependência angular dos espectros de RPE medidos, foi explicada pela presença de dois tipos de radicais, com um hidrogênio adicional: 2-H2 pireno e 3-H2 pireno. Estudamos o decaimento isotérmico do sinal de RPE e foram obtidos dois valores para a energia de ativação: (1,9 ± 0,1) eV e (1,93 ± 0,03) eV. / Single crystals of pirene, C16H10, irradiated with X-rays at room temperature was investigated by EPR to determine the types of stable free radicals formed by the radiation. Angular dependence of the EPR spectra was measured and explained on the basis that 2-H2 pyrene and 3-H2 pyirene were present. The annealing behavior of EPR signal was studied and we obtained two values of activation energy: (1,9 ± 0,1) eV and (1,93 ± 0,03) eV.