Thesis (Masters Diploma (Medical Technology)--Cape Technikon, Cape Town, 1995 / The objective of the present study vvas primarily to determine vvhether modifications to the existing osmium tetroxide/potassium ferrocyanide method could be used as a general ultrastructural glycogen stain and whether this glycogen, vvhen so contrasted, differed in appearance in different tumours, such as Evving's sarcoma, Leiomyosarcoma, Rhabdomyosarcoma and Hepatocellular carcinoma. Normal skeletal muscle and liver were used to obtain a standard for the appearance of glycogen, and then, with diagnostic criteria in mind, the four glycogen-rich tumours, mentioned above vvere examined to determine the appearance, distribution and amount of glycogen present in them. Modifications to the osmium tetroxide/potassium ferrocyanide (OPF) method consisted of raising the concentration of the ferrocyanide, and using no en bloc or thin section staining by any uranyl salt solutions, because solutions of uranyl salts leaches glycogen from tissue. This procedure resulted in extremely electron-dense intracellular glycogen being retained, vvhich aided diagnosis of the these tumours. At high magnification. (>X30000) there vvas no morphological difference betvveen the glycogen particles in the various tumours, so these particles as such could not be used as a diagnostic criterion. Existing methods for the demonstration of myeloperoxidase and platelet peroxidase vvere modified to obtain more precise localization of the diaminobenzidine (DAB) reaction product. Different anti-coagulants, one of which was heparin and a modified fixation procedure vvas follovved.

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

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

Mixed metal oxides are ionic compounds containing at least two metal ions within an oxide structure. The literature contains a plethora of examples of mixed metal oxides on the bulk scale, which have been well characterised, however, mixed metal oxides on the nanoscale are far less well understood. The work presented here investigates the Bi2O3-CeO2-Nb2O5 mixed oxide system and characterises the resulting nanoparticles and crystal structures. Although the parent oxides are well known and much work has previously been done in analysing their crystal structures, combinations of these oxides have not been well characterised, especially on the nanoscale. Using high resolution electron microscopy (HRTEM), powder X-ray diffraction (PXRD), electron dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) as analytical tools, the structures of the nanoparticles in this system have been explored. As each of the parent oxides possess useful properties, which have been utilised in industrial applications such as electrolyte components in solid oxide fuel cells and as catalysts in a range of chemical reactions, it was hypothesised that if all three metal ions could be contained in one particle they could show novel and interesting characteristics. It was proposed that due to the more relaxed crystal structure in nanoparticles, the solid solubility of the metal ions should be increased, and a solid solution of ions would form. This work presents results showing the synthesis of binary and ternary oxides in the nano-form within the Bi2O3-CeO2-Nb2O5 system, including quantitative analysis of these particles. Secondly, and most importantly, it presents the first successful synthesis of quaternary oxide nanoparticles containing bismuth, cerium and niobium using the low temperature resin-gel method. Finally, the work attempts to explain how and why the ions are ordered in a given arrangement, with bismuth showing a preference for surface site occupation, as shown by XPS data, and describes some preliminary computational results which corroborate the experimental data.

abstract: The research of this dissertation has primarily involved using transmission electron microscopy (TEM) techniques to study several semiconductor materials considered promising for future photovoltaic device applications. Layers of gallium phosphide (GaP) grown on silicon (Si) substrates were characterized by TEM and aberration-corrected scanning transmission electron microscopy (AC-STEM). High defect densities were observed for samples with GaP layer thicknesses 250nm and above. Anti-phase boundaries (APBs) within the GaP layers were observed at interfaces with the Si surfaces which were neither atomically flat nor abrupt, contradicting conventional understanding of APB formation. Microcrystalline-Si (μc-Si) layers grown on crystalline-Si (c-Si) substrates were investigated. Without nanoparticle seeding, an undesired amorphous-Si (a-Si) layer grew below the μc-Si layer. With seeding, the undesired a-Si layer grew above the μc-Si layer, but μc-Si growth proceeded immediately at the c-Si surface. Ellipsometry measurements of percent crystallinity did not match TEM images, but qualitative agreement was found between TEM results and Ultraviolet Raman spectroscopy. TEM and Xray spectroscopy were used to study metal-induced crystallization and layer exchange for aluminum/ germanium (Al/Ge). Only two samples definitively exhibited both Ge crystallization and layer exchange, and neither process was complete in either sample. The results were finally considered as inconclusive since no reliable path towards layer exchange and crystallization was established. Plan-view TEM images of indium arsenide (InAs) quantum dots with gallium arsenide antimonide (GaAsSb) spacer layers revealed the termination of some threading dislocations in a sample with spacer-layer thicknesses of 2nm, while a sample with 15-nm-thick spacer layers showed a dense, cross-hatched pattern. Cross-sectional TEM images of samples with 5-nm and 10-nm spacer-layer thicknesses showed less layer undulation in the latter sample. These observations supported photoluminescence (PL) and Xray diffraction (XRD) results, which indicated that GaAsSb spacer layers with 10-nm thickness yielded the highest quality material for photovoltaic device applications. a-Si/c-Si samples treated by hydrogen plasma were investigated using high-resolution TEM. No obvious structural differences were observed that would account for the large differences measured in minority carrier lifetimes. This key result suggested that other factors such as point defects, hydrogen content, or interface charge must be affecting the lifetimes. / Dissertation/Thesis / Doctoral Dissertation Physics 2020

The work is devoted to problems of electron microscopy, focusing on the scintillation detector, which is located in chamber separating the field from different pressures. Using of the CAD and CAE was created 3D model of the detector, which took place on calculations focused to influence of the performance of different types of air pumps at gas flow between the chambers. The results of individual variants are compared in graphic form and evaluated.

The interaction of emotion and memory is necessary for establishing a cognitive map including current context and past experiences, which is used by prefrontal cortex to regulate the internal state and guide goal directed actions and decision making. The amygdala, hippocampus and anterior cingulate cortex (ACC) play critical roles in these processes, but the organization of pathways between them is largely unknown in primates. This issue was addressed using neural tracers in rhesus monkeys to label the bidirectional pathways between amygdala and hippocampus and the unidirectional pathway from hippocampus to ACC. The amygdala sent a robust projection to hippocampus that formed large and closely spaced dual synapses on spines from the same dendritic segment, suggesting a strong influence. Further, amygdalar axon boutons innervated some disinhibitory calretinin neurons in CA1, suggesting enhanced excitatory influence. In contrast, in CA3 the amygdala pathway innervated calretinin and some of the powerful parvalbumin inhibitory neurons, which may help enhance memory of affective events. The reverse pathway from hippocampus densely and mainly targeted the ventro-medial part of the amygdala, including the basolateral (BL) and paralaminar basolateral (PLBL) nuclei. Hippocampal terminations formed synapses mostly on spines vii of presumed excitatory neurons. Some hippocampal terminations innervated inhibitory neurons in BL and PLBL and showed a rank of preference, by targeting mostly calretinin, and then calbindin and least parvalbumin inhibitory neurons. This pattern of innervation may allow contextual information represented by hippocampus to influence affective processes in the amygdala. The hippocampus sent strong projections to ACC (A32, A24a and A25) and targeted particularly A25, suggesting a role in affective and autonomic regulation. About 90% of hippocampal terminations in A25 innervated excitatory neurons, suggesting strong excitatory effects. The hippocampal pathway had a close relationship with postsynaptic D1 receptors in A25, especially in the deep layers. Dopamine has a strong influence in goal-directed actions, rewards, and attention in prefrontal cortex in primates, and may facilitate contextual information from the hippocampus to A25 to influence emotional regulation. The pathways studied were distinct, and suggest specific roles in emotional memory by the amygdala in hippocampus, in flexible learning and forgetting fear based on context transmitted from hippocampus to the amygdala, and in the synthesis of current context and past experience carried out by the hippocampal pathway to ACC to influence adaptive goal directed behavior. / 2021-09-27T00:00:00Z

No description available.