Recently, the rate of corrosion of copper water pipes in Bowling Green, Kentucky has unexpectedly accelerated. The specific reasons for this are unknown. Our aim is to elucidate the factors enhancing the corrosion and help understand the primary mechanisms of action. This will help in combating and reducing future corrosion incidents leading to pipe failure, thus reducing losses experienced when these pipes are replaced. This study seeks to explore the characteristics and factors involved. The scanning electron microscopy was used to obtain elemental composition, and images of both inside and outside of the corroded pipes. Strikingly, corrosion primarily occurred on the outside of the pipes, not inside. X-ray crystallography also was used to examine the pipes. The results showed that the interior of the pipes mostly consisted of SiO2, CuO2, CaCO3 while the exterior consisted of Cu2(OH)2CO3, Fe2Al2O4, CaCO3, SiO2 and Cu2O. There was no clear single factor for the corrosion observed. For further studies, we plan to long temporal experiments. The results from the study will help in minimizing the costs to the city in Bowling Green, Kentucky.

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

Spermiogenesis and ultrastructure of the spermatozoon of two bothriocephalidean cestodes, Oncodiscus sauridae and Senga sp., have been studied using transmission electron microscopy. The presence of a classical pattern for spermatological characters (spermiogenesis of type I with dense-material in early stages and sperm of type II with a characteristic ring of cortical microtubules in the anterior part) in Bothriocephalidea is discussed.

No description available.

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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.

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

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