The Microtubule (MT) network is a central component of the eukaryotic cell cytoskeleton. In the fission yeast S. pombe, a complex of three proteins specifically tracks MT +ends and stabilizes MTs in the cell. It is composed of the proteins Mal3, Tip1 and Tea2. Mal3, the S. pombe homologue of EB1, is a highly conserved ubiquitous protein found to be at the centre of many MT related processes. Tip1 is a CLIP170 homologue and Tea2 a kinesin-like motor protein. The mechanism by which they target the growing end of MTs and stabilize them is still unknown. A combination of biochemistry, electron microscopy and crystallography were used in an attempt to get a more precise understanding of the MT stabilization by this +Tip complex. Protein-A pull-down of the endogenous complex and analysis of its constituents by mass spectrometry revealed that Tea2 and Tip1 form a tight stoichiometric complex, making a much more labile interaction with Mal3. Biochemical experiments, light scattering and DIC microscopy demonstrate that Mal3 stabilizes the MT structure in a stoichiometric fashion by suppressing catastrophe events. 3D helical reconstruction of electron micrographs of Mal3 bound to the MT show that it most probably stabilizes the MT structure by bridging protofilaments together. Deletion mutant analysis suggests that contact with one of the protofilaments is via an interaction between the charged tails of tubulin and Mal3. Mal3 MT binding domain structure was solved by X-ray crystallography so that eventually it may be docked into a higher resolution electron microscopy map to provide a more precise structural insight on how Mal3 stabilizes the MT lattice. The EM analysis also shows that Mal3 regulates MT structure in vitro by restraining their protofilament number to 13, which is the number always found in vivo, and by driving the assembly of MTs with a high proportion of A-lattice. It is the first time that a protein is found to promote formation of A-lattice MTs. The fact that EB1 is such a ubiquitous protein reopens the question of MT structure in cells and has important implications for in vivo MT dynamics.

Avec les dernières avancées en matière de nanotechnologies, il est devenu possible de concevoir, avec une grande efficacité, de nouveaux dispositifs et systèmes nanométriques. Il en résulte la nécessité de développer des méthodes de pointe fiables pour la nano manipulation et la nano caractérisation. La d´étection directe par l’homme n’ étant pas une option envisageable à cette échelle, les tâches sont habituellement effectuées par un opérateur humain expert `a l’aide de microscope électronique à balayage équipé de dispositifs micro nano robotiques. Toutefois, en raison de l’absence de méthodes efficaces, ces tâches sont toujours difficiles et souvent fastidieuses à réaliser. Grâce à ce travail, nous montrons que ce problème peut être résolu efficacement jusqu’ à une certaine mesure en utilisant les informations extraites des images. Le travail porte sur l’utilisation des images électroniques pour développer des méthodes automatiques fiables permettant d’effectuer des tâches de nano manipulation et nano caractérisation précises et efficaces. En premier lieu, puisque l’imagerie électronique à balayage est affectée par les instabilités de la colonne électronique, des méthodes fonctionnant en temps réel pour surveiller la qualité des images et compenser leur distorsion dynamique ont été développées. Ensuite des lois d’asservissement visuel ont été développées pour résoudre deux problèmes. La mise au point automatique utilisant l’asservissement visuel, développée, assure une netteté constante tout au long des processus. Elle a permis d’estimer la profondeur inter-objet, habituellement très difficile à calculer dans un microscope électronique à balayage. Deux schémas d’asservissement visuel ont été développés pour le problème du nano positionnement dans un microscope électronique. Ils sont fondés sur l’utilisation directe des intensités des pixels et l’information spectrale, respectivement. Les précisions obtenues par les deux méthodes dans diff érentes conditions expérimentales ont été satisfaisantes. Le travail réalisé ouvre la voie à la réalisation d’applications précises et fiables telles que l’analyse topographique,le sondage de nanostructures ou l’extraction d’ échantillons pour microscope électronique en transmission. / With the latest advances in nanotechnology, it became possible to design novel nanoscale devicesand systems with increasing efficiency. The consequence of this fact is an increase in the need for developing reliable and cutting edge processes for nanomanipulation and nanocharacterization. Since the human direct sensing is not a feasible option at this particular scale, the tasks are usually performedby an expert human operator using a scanning electron microscope (SEM) equipped withmicro-nanorobotic devices. However, due to the lack of effective processes, these tasks are always challenging and often tiresome to perform. Through this work we show that, this problem can be tackle deffectively up to an extent using the microscopic vision information. It is concerned about using the SEM vision to develop reliable automated methods in order to perform accurate and efficient nanomanipulation and nano characterization. Since, SEM imaging is affected by the non-linearities and instabilities present in the electron column, real time methods to monitor the imaging quality and to compensate the time varying distortion were developed. Later, these images were used in the development of visual servoing control laws. The developed visual servoing-based autofocusing method ensures a constant focus throughout the process and was used for estimating the inter-object depth that is highly challenging to compute using a SEM. Two visual servoing schemes were developed toperform accurate nanopositioning using a nanorobotic station positioned inside SEM. They are basedon the direct use of global pixel intensities and Fourier spectral information respectively. The positioning accuracies achieved by both the methods at different experimental conditions were satisfactory.The achieved results facilitate in developing accurate and reliable applications such as topographic analysis, nanoprobing and sample lift-out using SEM.

The original work presented in this thesis describes research into Si-based luminescent materials, prepared specifically by ion implantation and rapid thermal processing of thermal oxide films. An in-depth optical characterisation, employing photoluminescence (PL) and Raman spectroscopy was complimented with electron microscopy, revealing the source of efficient room temperature PL as nano-scale silicon inclusions (Si-NCs). The evolution of the Si-NC size and density with isothermal and isochronal annealing may be described using classical thermodynamics according to a diffusion limited, Ostwald ripening process. Values for the coarsening rate and activation energy, extracted from the evolution of the Si-NC size with annealing indicate that the transport of Si atoms and precipitate formation are enhanced in ion implanted films, attributable to the presence of vacancy and interstitial defects generated during ion irradiation. The PL and Raman spectra are well correlated with the evolving Si-NC size and density according to the quantum confinement (QC) model in which samples containing larger clusters emit at longer wavelengths. However, the formation of bound exciton states within the band gap of small clusters (< 2nm), as a result of specific surface chemistries, suppresses higher energy emissions. The increase in PL intensity with annealing was exactly correlated with the increase in PL lifetime, characteristic of the removal of non-radiative defects. A dependence of the PL dynamics on emission energy, with higher energies exhibiting shorter lifetimes, further evidences the QC effect. Blue shifted emission at high excitation flux and/or low temperature is correspondent with the slower PL dynamics and preferential saturation at longer wavelengths. Raman spectra were fit using a phonon confinement model, from which Si-NC size distributions were extracted and found to compare favourably with those obtained from TEM images. Stresses in the films, determined from the Raman peak position, were used as an independent method for calculating the Si surface energy, which is very close to the literature values. A single, high temperature anneal of Si and erbium (Er) co-doped films revealed a preferential aggregation of Er at the Si-NC formation site, which is of particular importance for the photo-sensitization of Er PL around 1.5μm. The Er PL was enhanced in the presence of Si-NCs by several orders of magnitude compared with a reference SiO2:Er. Whilst broadband pumping of the Er via Si-NCs evidences a non-resonant energy transfer mechanism with an efficiency which depends on the Si-NC size, the process is limited at high excitation flux by a combination of low sensitizer (Si-NC) density and non-radiative losses. Finally the Si-NC PL intensity in phosphorus (P) co-doped films was studied and found to depend strongly on the annealing conditions and P concentration. For lower temperature treatments, a factor 2 PL enhancement, relative to an un-doped reference was obtained, attributed to the passivation of Si-NC surface defects. Higher temperature treatments resulted in the monotonic quenching of the PL with increasing P concentration, attributed to the introduction of an efficient Augerre combination channel as a result of the ionization of P-donors inside large Si-NCs. A simple statistical model predicts this behaviour and provides an incidental estimate of the Si-NC size.

Graphene, a one-atom thick sheet of carbon, is the thinnest, strongest and most electrically conductive material ever discovered. Alongside carbon nanotubes it is part of the group of nanocarbons whose unique properties have sparked huge interest in possible applications, including electronic devices, solar cells and biosensors. Doping of these materials allows for the modification of their optical and electronic properties,which is crucial to realising these applications. Studying the properties of these doped materials at atomic resolution and finding controllable and industrially scalable routes to doping, such as low energy ion implantation, are thus essential if they are to becomethe materials of the future. In this thesis, highly localised optical enhancements in metal doped graphene are studied using energy-filtered transmission electron microscopy in a monochromated and aberration corrected electron microscope. The ideal conditions for imaging the low energy loss region of graphene using EFTEM are discussed and new methods to compensate for image artifacts when using this technique at high resolution are presented. Density functional theory is used to reveal new visible spectrum plasmon excitations in the electron energy loss spectra of boron and nitrogen doped nanocarbons. Atomic resolution scanning transmission electron microscopy and nanoscale electron energy loss spectroscopy are used to investigate controllable and defect-free substitutional doping of suspended graphene films through low energy ion implantation. Computational methods for filtering high angle annular dark field images are shown and software for the automated processing and spectroscopic analysis of these images is developed.

A number of investigators have reported enhancement in oxidation and wear resistant of carbon-carbon composites (CCC) in the presence of protective coating layers. However, application of a surface and subsurface coating system that can preserve its oxidation and wear resistance along with maintaining lubricity at high temperature remains unsolved. To this end, thermodynamically stable protective oxides (ZnO/Al2O3/ZrO2) have been deposited by atomic layer deposition (ALD) to infiltrate porous CCC and graphite foams in order to improve the thermal stability and wear resistance in low and high speed sliding contacts. Characterization of microstructural evolution was achieved by using energy dispersive x-ray spectroscopy (EDS) mapping in scanning electron microscope (SEM) coupled with focused ion beam (FIB), x-ray tomography, high resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) and X-ray diffraction (XRD). Evaluation of the tribological properties of CCC coated with abovementioned ALD thin films were performed by employing low speed pure sliding tribometer and a high speed/frequency reciprocating rig to simulate the fretting wear behavior at ambient temperature and elevated temperatures of 400°C.It was determined with x-ray tomography imaging and EDS mapping that ALD ZnO/Al2O3/ZrO2 nanolaminates and baseline ZrO2 coatings exhibited excellent conformality and pore-filling capabilities down to ~100 μm and 1.5 mm in the porous CCC and graphite foam, respectively, which were dependent on the exposure time of the ALD precursors. XRD and HRTEM determined the crystalline phases of {0002} textured ZnO (wurtzite), amorphous Al2O3, and {101}-tetragonal ZrO2. Significant improvements up to ~65% in the sliding and fretting wear factors were determined for the nanolaminates in comparison to the uncoated CCC. A tribochemical sliding-induced mechanically mixed layer (MML) was found to be responsible for these improvements. HRTEM confirmed the presence of a high density of ZnO shear-induced basal stacking faults inside the wear tracks responsible for intrafilm shear velocity accommodation that mitigated friction and wear.

Orientador: Ines Joekes / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-07T21:43:58Z (GMT). No. of bitstreams: 1 Wagner_RitadeCassiaComis_D.pdf: 5300466 bytes, checksum: b220b80949a0b5e00e05ecef6360d5ac (MD5) Previous issue date: 2006 / Resumo: O cabelo é uma estrutura protéica de queratina formada por quatro estruturas principais: as cutículas, o córtex, o cimento intercelular (CMC) e a medula. Esta última nem sempre está presente no fio e, por acreditar-se que sua influência nas propriedades da fibra é negligenciável, foi pouco estudada. Este trabalho almeja esclarecer as estruturas da medula e verificar sistematicamente se ela afeta alguma propriedade na fibra. Os fios medulados e sem medula provenientes do mesmo couro cabeludo foram identificados e separados em mechas utilizando um micro-estereoscópio. Encontraram-se dois tipos de medula (fina e grossa) que foram diferenciadas por microscopia eletrônica de varredura (MEV) e de transmissão (MET). A medula tem uma estrutura esponjosa composta por três unidades principais: a fibrilar (desalinhada com as fibrilas do córtex), os glóbulos e uma camada de CMC na interface com o córtex. Por MET constatou-se que a medula fina é morfologicamente diferente da medula grossa. A medula fina apresenta contraste, interface limitada pelo CMC, nenhum grânulo de melanina e menor diâmetro. A medula grossa apresenta mais glóbulos, bem como maiores dimensões das cavidades, alguns grânulos de melanina disformes e organização gradual das células de fora para dentro. Essas características morfológicas sugerem que a medula seria um córtex em estágio atrasado de formação. Utilizando-se um espectrofotômetro de refletância difusa (ERD), verificou-se que os fios com medula são mais escuros, menos vermelhos e menos amarelos que os fios sem medula oriundos do mesmo couro cabeludo. Sugere-se que as cavidades da medula causem o espalhamento e o confinamento de luz pela diferença de índice de refração com o córtex, diminuindo, então, a reflexão externa da fibra, já que praticamente não possui melanina. Para a mecha estudada, a diferença de cor total está em 4,7 unidades de cor e é visível a olho nu. A medula, então, deve ser considerada em estudos de cor, juntamente com as melaninas e as condições de preservação das cutículas. Já nas propriedades mecânicas, a medula causa uma maior heterogeneidade nas curvas de tensão-deformação, mas não muda os valores médios das propriedades estudadas. Os fios medulados são mais espessos que fios sem medula. Descontando-se o valor do diâmetro da medula do diâmetro total da fibra, têm-se valores aproximados aos dos fios sem medula. A heterogeneidade observada é proveniente da diferença percentual que o diâmetro da medula representa do diâmetro total da fibra. Observaram-se mudanças estruturais quando o cabelo com medula fina é submetido à imersão em SDS 10 % e à 75 °C, transformando-se em medula grossa após os tratamentos / Abstract: Human hair is a keratinous material divided into four main units: cuticles, cortex, intercellular cement (CMC) and medulla. The last one could be present or not in the shafts. There are few studies about it mainly because it is believed to have small or no influence on any hair property. The present work aims to clarify the medulla structure and to systematically verify if mechanical or color properties are affected by its presence in the fiber. Medullated and unmedullated fibers from the same scalp were identified by stereo-microscopy and separated into tresses. Two kinds of medulla were found: thin and thick medulla. Their morphology was characterized by scanning (SEM) and transmission (TEM) electron microscopy. Medulla has a sponge structure composed by three units: fibril (not aligned longitudinally as in the cortex), globular and CMC layer in the interface with the cortex. Thin and thick medullas are different in TEM. Thin medulla has contrast, CMC limited interface, no melanin and smaller diameter. Thick medulla has more globular structures, larger cavities, some elliptical melanin granules and a gradual organization from the outside to the inner side of the medulla. These data suggest that medulla is in an earlier stage of the differentiation process compared to the cortex. Color data obtained using a diffuse reflectance spectrophotometer showed that unmedullated fibers are clearer, redder and yellowier than medullated fibers. Once that medulla presents no melanin, we suggest that the medulla cavities cause scattering and confinement of light by the difference with the refractive index of cortex which decreases the external reflectance of the fiber. For the studied tress, the total color difference was 4.7 (visible to naked eyes). Thus, medulla together with melanin and cuticles must now be considered in studies of hair color. Average values of the mechanical properties are similar for unmedullated and medullated fibers. However, higher dispersion in data for medullated fibers is observed. Unmedulated fibers are more uniform and show smaller diameters. These data indicate that the air cavities in medulla could act as defects but do not interfere in the crystalline character of the fiber. Thus, the heterogeneity observed might be attributed to the difference between the medulla diameter with the whole fiber diameter. Thin medulla regions became thick medulla after immersion in SDS 10 % and after 24 h at 75 °C / Doutorado / Físico-Química / Doutor em Ciências

>Magister Scientiae - MSc / Polymer electrolyte membrane fuel cells (PEMFCs) among other fuel cells are considered the best candidate for commercialization of portable and transportation applications because of their high energy conversion and low pollutant emission. Recently, there has been significant interest in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs), due to certain advantages such as simplified system and better tolerance to CO poisoning. Cost, durability and the reliability are delaying the commercialization of PEM fuel cell technology. Above all durability is the most critical issue and it influences the other two issues. The main objective of this work is to study the durability of membrane electrode assemblies (MEAs) for HT-PEMFC. In this study the investigation of commercial MEAs was done by evaluating their performance through polarization studies on a single cell, including using pure hydrogen and hydrogen containing various concentrations of CO as fuel, and to study the performance of the MEAs at various operating temperatures. The durability of the MEAs was evaluated by carrying out long term studies with a fixed load, temperature cycling and open circuit voltage degradation. Among the parameters studied, significant loss in the performance of the MEAs was noted during temperature cycling. The effect of temperature cycling on the performance of the cell showed that the performance decreases with increasing no. of cycles. This could be due to leaching of acid from the cell or loss of electrochemically active surface area caused by Pt particle size growth. For example at 160°C, a performance loss of 3.5% was obtained after the first cycle, but after the fourth cycle a huge loss of 80.8% was obtained. The in-house MEAs with Pt-based binary catalysts as anodes were studied for CO tolerance, performance and durability. A comparison of polarization curves between commercial and in-house MEAs illustrated that commercial MEA gave better performance, obtaining 0.52 A/cm² at 0.5V and temperature of 160°C, with in-house giving 0.39A/cm² using same parameters as commercial. The CO tolerance of both commercial and in-house MEA was found to be similar. In order to increase the CO tolerance of the in-house MEAs, Pt based binary catalysts were employed as anodesand the performance was investigated In-house MEAs with Pt/C and Pt-based binary catalysts were compared and a better performance was observed for Pt/C than Pt-alloy catalysts with Pt-Co/C showing comparable performance. At 0.5 V the performance obtained was 0.39 A/cm2 for Pt/C, and 0.34A/cm²,0.28A/cm²,0.27A/cm² and 0.16A/cm² were obtained for Pt-Co/C, Pt-Fe/C, Pt-Cu/C and Pt-Ni respectively. When the binary catalysts were tested for CO tolerance, Pt-Co showed no significant loss in performance when hydrogen containing CO was used as anode fuel. Scanning electron microscopy (SEM) revealed delamination between the electrodes and membrane of the tested and untested MEA's. Membrane thinning was noted and carbon corrosion was observed from the tested micro-porous layer between the gas diffusion layer (GDL) and catalyst layer (CL).

Estudos morfológicos representam ferramentas básicas para ampliação do conhecimento sobre determinado táxon e abrem caminhos para o desenvolvimento de outros estudos em diversas áreas como taxonomia, filogenia, etologia e ecologia. Neste trabalho, buscamos aprimorar o conhecimento morfológico na família Pentatomidae, investigando as variações presentes nas pernas de percevejos e como elas se desenvolvem ao longo do ciclo de vida. Estudando comparativamente as expansões tibiais e o aparato tibial na subfamília Asopinae, e verificamos que ambas as estruturas possuem uma ampla variação morfológica. As expansões podem estar presentes nas superfícies dorsal e ventral da tíbia, ou apenas na dorsal. A estrutura pode apresentar diferentes tamanhos entre as espécies, podendo ser até duas vezes a largura do eixo central da tíbia como nos gêneros Cazira e Heteroscelis, ou em outros casos como Alceorrhynchus, que se apresenta de forma diminuta. Além disso, as expansões podem ocorrer ao longo de toda a tíbia, ou apenas apicalmente. Em relação ao aparato tibial, verificamos que o número de cerdas é bastante variável entre as espécies analisadas, e que possui relação com o tamanho geral do inseto. Ainda, verificamos que a região circundante à estrutura apresenta morfologia variável. Com base nas variações encontradas, dez caracteres morfológicos foram propostos. Além dos adultos, estudamos a morfologia e alometria da tíbia ao longo da ontogenia em nove espécies de Pentatomidae das subfamílias Asopinae, Pentatominae e Edessinae. Foi constatado que o número de cerdas aumenta em cada estágio de desenvolvimento nas espécies de Asopinae, enquanto nas demais o número se mantém praticamente o mesmo. A alometria do aparato tibial se demonstrou positiva para todas as espécies de Asopinae nos testes realizados, enquanto nas subfamílias Pentatominae e Edessinae a alometria da estrutura foi maioritariamente negativa ou isométrica. Foi demonstrado que assim como em outros insetos, as pernas apresentam um crescimento acelerado em comparação com outras estruturas do corpo, neste caso, da cabeça. Além disso, constatamos que a largura de tíbia apresenta uma queda de tamanho do quinto ínstar para o estágio Adulto, e hipotetizamos que este fenômeno possa ter relação com a perda de estruturas presentes nas pernas das ninfas responsáveis por dar maior suporte ao peso do inseto. Os estágios imaturos de Tynacantha marginata Dallas são descritos, estruturas corporais são exploradas e comparadas morfologicamente, e características diagnósticas que permitem a identificação dos ovos e ninfas da espécie são fornecidas. / Morphological studies are basic tools to increase knowledge about a given taxon, opening paths for the development of other studies in several areas such as taxonomy, phylogeny, ethology and ecology. In this work, we aimed to improve the morphological knowledge in the Pentatomidae family, examining the variations present in the legs of stink bugs and how they develop throughout the life-cycle. Comparatively studying the tibial expansions and the foretibial apparatus in the Asopinae subfamily, we found that both structures have a wide morphological variation. The expansions may be present on the dorsal and ventral surfaces of the foretibia, or only on the dorsal surface. The structure can present different sizes between the species, being able to be up to twice the width of the tibial axis as in the genus Cazira and Heteroscelis, or in other cases like Alceorrhynchus, appears in a diminutive form. Besides, the expansions may occur along the entire tibia, or only apically. In relation to the foretibial apparatus, we verified that the number of setae is quite variable among the analyzed species, and that it is related with the general size of the insect. Also, we verified that the region surrounding the structure presents variable morphology. Based on the variations found, ten morphological characters are proposed. In addition to the adults, we studied the morphology and allometry of the foretibia along the ontogeny in nine species of Pentatomidae of the subfamilies Asopinae, Pentatominae and Edessinae. It was observed that the number of setae increases at each stage of development in the Asopinae species, while in the others the number remains practically the same. Allometry of the tibial apparatus was shown to be positive for all Asopinae species in the performed tests, while in the Pentatominae and Edessinae subfamilies the allometry of the structure was mostly negative or isometric. It has demonstrated that, as in other insects, the legs exhibit accelerated growth compared to other structures of the body, in our case, the head. In addition, we verified that tibia width shows a decrease in size of the fifth instar for the adult stage, and hypothesized that this phenomenon is related to the loss of structures present in the legs of the nymphs responsible for giving support to the weight of the insect. The immature stages of Tynacantha marginata Dallas are described, body structures are explored and morphologically compared and diagnostic features that allow identification of the eggs and nymphs of the species are provided.

abstract: A new nanoparticle deposition technique, Aerosol Impaction-Driven Assembly (AIDA), was extensively characterized for material structures and properties. Aerogel films can be deposited directly onto a substrate with AIDA without the long aging and drying steps in the sol-gel method. Electron microscopy, pore size analysis, thermal conductivity, and optical measurements show the nanoparticle (NP) films to be similar to typical silica aerogel. Haze of nanoparticle films modeled as scattering sites correlates strongly with pore size distribution. Supporting evidence was obtained from particle sizes and aggregates using electron microscopy and small-angle X-ray scattering. NP films showed interlayers of higher porosity and large aggregates formed by tensile film stress. To better understand film stress and NP adhesion, chemical bonding analyses were performed for samples annealed up to 900 °C. Analysis revealed that about 50% of the NP surfaces are functionalized by hydroxyl (-OH) groups, providing for hydrogen bonding. Ellipsometric porosimetry was used to further understand the mechanical properties by providing a measure of strain upon capillary pressure from filling pores. Upon annealing to 200 °C, the films lost water resulting in closer bonding of NPs and higher Young’s modulus. Upon further annealing up to 900 °C, the films lost hydroxyl bonds while gaining siloxane bonds, reducing Young’s modulus. The application of ellipsometric porosimetry to hydrophilic coatings brings into question the validity of pore size distribution calculations for materials that hold onto water molecules and result in generally smaller calculated pore sizes. Doped hydrogenated microcrystalline silicon was grown on crystalline silicon NPs, as a test case of an application for NP films to reduce parasitic absorption in silicon heterojunction solar cells. Parasitic absorption of blue light could be reduced because microcrystalline silicon has a mix of direct and indirect bandgap, giving lower blue absorption than amorphous silicon. Using Ultraviolet Raman spectroscopy, the crystallinity of films as thin as 13 nm was determined rapidly (in 1 minute) and non-destructively. A mono-layer of nanocrystals was applied as seeds for p-doped microcrystalline silicon growth and resulted in higher crystallinity films. Applications of the method could be explored for other nanocrystalline materials. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2020

Orientador: Regina Helena Garcia Martins / Resumo: Introdução: denomina-se presbifonia o conjunto de alterações nos padrões vocais consequentes ao envelhecimento da laringe, podendo cursar com sintomas de disfonia, voz fraca, trêmula e baixa. Estudos histológicos e imunohistoquímicos da presbilaringe demonstram atrofia do epitélio, da lâmina própria e do músculo vocal, além de aumento de fibras colágenas e diminuição de fibras elásticas e das proteínas não fibrosas da matriz extracelular. Os estudos de microscopia eletrônica da presbilaringe são escassos e podem acrescentar detalhes ultraestruturais importantes e auxiliar na compreensão da fisiopatologia da presbifonia. Objetivos: descrever os achados de microscopia eletrônica de varredura e transmissão da prega vocal senil. Casuística e métodos: Foram removidas 16 laringes humanas durante necrópsia e distribuídas em dois grupos: controle (n-8; idade 30 - 50 anos; 6F e 2M) e idoso (n-8; idade 75- 92 anos; 6F e 2M). As porções medianas de ambas as pregas vocais foram dissecadas, fixadas em glutaraldeído 2,5% e preparadas para exames de microscopia eletrônica de varredura e transmissão. A espessura do epitélio foi medida nas fotografias de microscopia eletrônica de varredura, com aumentos semelhantes, utilizando-se o programa de morfometria digital Scandium. Resultados: Microscopia eletrônica de varredura: Grupo controle: epitélio composto por 5 a 7 camadas de células sobrepostas, raras células em descamação, e discreta ondulação. Lâmina própria com rede uniforme de fibras col... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction: Presbyphonia is called the set of changes in vocal patterns consequent aging of the larynx, which can present with symptoms of dysphonia, weak voice, trembling and low. Histological and immunohistochemical studies of presbylarynx show atrophy of the epithelium, lamina propria and the vocal muscle, and increase of collagen fibers and diminution of elastic fibers and non-fibrous proteins of the extracellular matrix. The studies of electron microscopy of presbylarynx are scarce and can add significant ultrastructural details contribute to further understanding of the pathophysiology of presbyphonia. Objectives: To describe the findings of scanning and transmission electron microscopy of senile vocal folds. Methods: 16 human larynx were removed during autopsy and distributed into two groups: control (n-8; age 30-50 years; 6F and 2M) and elderly (n-8, age 75- 92 years; 6F and 2M). The median portions of the right and left vocal folds were dissected, fixed in 2.5% glutaraldehyde and prepared for examination using scanning and transmission electron microscopy respectively. The thickness of the epithelium was analyzed in the pictures of the scanning electron microscopy with similar magnification, using the Scandium morphometric digital program. Results: Scanning electron microscopy: Control Group: epithelium composed of 5-7 layers of overlapping cells, rare cells in flaking and slight ripple. Lamina propria with uniform network of collagen and elastic fibers running pa... (Complete abstract click electronic access below) / Mestre