O objetivo deste trabalho foi avaliar diferentes aspectos da displasia fibrosa por meio da tomografia computadorizada (sítio ósseo da lesão, padrões de imagem, expansão e/ou destruição óssea) e correlacioná-los com a classificação da lesão (displasia fibrosa monostótica e craniofacial) e o sexo dos pacientes, além de sugerir uma padronização da classificação destas imagens. Foram avaliados 52 pacientes com displasia fibrosa monostótica e craniofacial por meio de cortes axiais e coronais de tomografia computadorizada. Os padrões de imagem na tomografia computadorizada foram divididos em três aspectos: hiperdenso e homogêneo (“vidro despolido"); pagetóide (hipo e hiperdenso); hiperdenso e esclerótico e hipodenso (Apesar de não ter encontrado na minha tese, este foi um padrão citado). Quando comparados os sexos, observou-se maior proporção de imagens padrão pagetóide e esclerótico no sexo feminino e padrão de imagem “vidro despolido" no sexo masculino. O padrão de imagem “vidro despolido" predominou entre as displasias fibrosas monostóticas; entre as displasias fibrosas craniofaciais, as imagens padrão “vidro despolido" e pagetóide apresentaram igual freqüência. As imagens escleróticas apresentaram proporção semelhante nos dois casos. Nos sítios ósseos com displasia fibrosa monostótica, o padrão “vidro despolido" foi predominante no esfenóide e na maxila. Além disso, foi o único padrão observado nos ossos frontal e temporal. O padrão pagetóide foi predominante na mandíbula e foi o único padrão encontrado no occipital. O padrão esclerótico só foi encontrado no temporal. Nos sítios ósseos com displasia fibrosa craniofacial, foram observados todos os três padrões de imagem no esfenóide, zigomático, maxila, etmóide, frontal e osso temporal. O padrão pagetóide foi encontrado em todos os sítios ósseos com displasia fibrosa craniofacial. O teste de Fisher mostrou não haver nenhuma associação estatística entre padrões de imagem e classificação da lesão para cada sítio ósseo (p > 0,05). Independentemente do padrão de imagem, todas as lesões apresentaram expansão da cortical. No entanto, somente as lesões com padrão pagetóide apresentaram destruição da cortical. A tomografia computadorizada é essencial na avaliação da extensão e do padrão de imagem da lesão. Uma nova padronização da classificação das imagens foi sugerida para um melhor entendimento e tratamento da doença quando correlacionada com o sítio ósseo. / The aim of this study was to determine the different computed tomography aspects (site of involvement of the lesion per bone, pattern of imaging and behavior (expansive and/or destructive) of patients with monostotic fibrous dysplasia and craniofacial fibrous dysplasia considering sex and the bone locations and to suggest a standard imaging classification. 52 patients with monostotic fibrous dysplasia or craniofacial fibrous dysplasia were studied through CT (axial and coronal slices). The images were categorized in four patterns: 1) “ground glass", 2) pagetoid, 3) sclerotic and 4) hypodense. When the two sexes were compared, a greater proportion of pagetoid and esclerotic patterns was observed in the female while “ground-glass" in the male. The “ground-glass" pattern was predominant in the cases of monostotic fibrous dysplasia . In addition, the ground-glass" and pagetoid patterns showed equal frequency. The sclerotic images showed similar proportion in both cases. In the bone locations with monostotic fibrous dysplasia, the “ground-glass" pattern was predominant in the sphenoid and maxilla. In addition, it was the only pattern observed in the frontal and parietal bones. The pagetoid pattern was predominant in the mandible and it was the only pattern observed in the occipital. The sclerotic pattern was only found in the temporal bone. In the bone locations with craniofacial fibrous dysplasia, all patterns of imaging in sphenoid, zygoma, maxilla, ethmoid, frontal and temporal bones were observed. Furthermore, all the bone locations with craniofacial fibrous dysplasia showed the pagetoid pattern. When the Fisher test was used, statistically significant association between imaging pattern and lesion classification considering bone location was not observed (p>0.05). All lesions showed expansion of the cortical and only the lesions with the pagetoid pattern showed destruction of the cortical. Computed tomography determined the extension and imaging patterns of the bone affected with monostotic fibrous dysplasia and craniofacial fibrous dysplasia. A standard imaging classification could be established in order to clarify the diagnosis and treatment of these lesions.

A displasia fibrosa é uma alteração de desenvolvimento caracterizada pela substituição do osso normal por tecido conjuntivo denso e trabéculas ósseas imaturas, geralmente encontrada em adolescentes e adultos jovens. Uma alteração genética que envolve a proteína Gs-alfa parece ser a base do processo. A exata incidência e prevalência são difíceis de estabelecer, mas as lesões representam cerca de 5% a 7% dos tumores ósseos benignos. Nos ossos craniofaciais tem predileção pela maxila, podendo causar deformidade grave e assimetria, afetando igualmente ambos os sexos. Radiograficamente, pode apresentar diferentes padrões de imagem dependendo do grau de mineralização e maturação da lesão. .A avaliação da displasia fibrosa nas radiografias da região craniofacial pode ser difícil por causa das aparências variáveis e das estruturas que se sobrepõem, de modo que a tomografia computadorizada é um recurso relevante para o seu correto diagnóstico e planejamento de tratamento. O objetivo deste estudo foi caracterizar a displasia fibrosa através da análise da lacunaridade, um método multiescala para descrever padrões de dispersão espacial. Foram avaliados 10 pacientes (6 homens e 4 mulheres) comprometendo a maxila em sua grande maioria. Para a análise da lacunaridade, empregou-se cortes tomográficos axiais e coronais e, posteriormente, selecionou-se as regiões de interesse das áreas displásicas e do osso normal contralateral por meio do software MATLAB®. Após testes e análises estatísticas, concluiu-se que os cortes coronais, com ampliação de 3x do seu tamanho original, mostraram superioridade em relação aos axiais e, que a lacunaridade foi menor nas áreas da região displásica em relação ao osso normal, ou seja, a primeira apresentou uma maior homogeneidade de textura que a segunda. Mediante isso, pela técnica da validação cruzada leave-one-out é possível separar os grupos com uma alta acurácia (94,75%) concluindo-se que a lacunaridade é um método de análise de imagens contributivo na caracterização da displasia fibrosa. / Fibrous dysplasia is an alteration of development characterized by replacing normal bone for dense connective tissue and immature trabecular bones, typically found in teenagers and young adults. Genetic modification which involves alpha-Gs protein appears to be the basis of the process. The exact incidence and prevalence are difficult to be established, but injuries represent about 5% to 7% of benign bone tumors. On the craniofacial bones, the tumors have a predilection for the maxilla and often can cause severe deformity and asymmetry affecting both sexes equally. Radiographically, it may have different patterns depending on the image degree of mineralization and maturation of the lesion. The evaluation of radiographs of fibrous dysplasia in the craniofacial region can be difficult because of the different appearances and structures that overlaps, however, CT is an important resource for proper diagnosis and treatment planning. The aim of this study was to characterize the fibrous dysplasia by analyzing the lacunarity which is a multiscale method to describe patterns of spatial dispersion. We evaluated 10 patients (6 males and 4 females) and the maxillary was the most affected area. To the lacunarity analysis, we used an axial and coronal view and then were selected the regions of interest in the areas of dysplastic and contralateral normal bone by means of MATLAB® software. After tests and statistical analysis can be conclued that the coronal magnification 3x its original size showed superiority compared to thrust, and that the lacunarity was lower in the areas of dysplastic region in relation to normal bone, namely the first presented a more uniform texture than the second. Through this, the technique of cross-validation \"leave-one-out\" is possible to separate the groups with a high accuracy (94.75%) concluding that the lacunarity is a method of image analysis to characterize the contributory fibrous dysplasia.

Os compósitos reforçados com fibras naturais são uma opção frente a fibrocimentos com amianto, devido à grande disponibilidade de fibras naturais como as de coco, sisal além das fibras de celulose. Aspectos relacionados com a durabilidade precisam ser melhorados, podendo ser citado a diminuição da resistência das fibras quando em meio alcalino causando a perda de propriedades mecânicas dos compósitos. Uma alternativa a esse problema é o uso de pozolana que irá consumir o hidróxido de cálcio proveniente da hidratação do cimento Portland, resultando em fases hidratadas como o C-S-H e aluminatos de cálcio, contribuindo assim, para a redução da alcalinidade e para o aumento da resistência mecânica. A metodologia adotada consistiu da análise do efeito de ciclos de molhagem e secagem quanto à formação de produtos da hidratação do cimento e da reação pozolânica a partir de formulações de cimento, filler dolomito, pozolana (metacaulim ou sílica ativa) e fibras de PVA (polivinil álcool) e celulose. As pozolanas empregadas foram efetivas no consumo de hidróxido de cálcio, porém não se constatou grandes ganhos mecânicos devido à degradação da matriz, observada em 250 ciclos, causada pela formação de hidróxido de magnésio com caráter expansivo. As hipóteses para a causa da formação de brucita consistem da reação de desdolomitização do filler dolomito ou da hidratação do periclásio que compõe o cimento Portland. / Composites reinforced with natural fibers are a good asbestos fibercomposites replacement material, as a result of the great natural fiber avaibility such as coco nut, sisal and cellulose. Durability aspects need to be improved, like the decrease of fiber resistance in alkaline environment causing the loss of mechanical properties of the composites. An alternative way to solve this problem is using pozzolan. It will react with calcium hydroxide formed by Portland cement hydration and will provide hydration phases as C-S-H and calcium aluminate hydrated, which contributes for the alkaline reduction and in an increase of mechanical performance. The methodology analyzes the effect of wet/dry cycles in composites among the hydration of cement and pozzolanic reaction in composite formulation made with cement, dolomite filler, pozzolan (metakaolin or silica fume) and PVA and cellulose fibers. The pozzolans used in this study consumed almost calcium hydroxide, although low mechanical properties were found. The matrix degradation with expansive brucite formation is explained with two hypotheses: dedolomitization reaction from dolomite filler or periclase hydration from Portland cement observed from 250 cycles.

Cette thèse traite de la simulation numérique de systèmes composés de nombreuxobjets distincts, et dont le principal mécanisme d'interaction consiste en des contacts inélastiques avec frottement solide.On trouve de nombreuses occurrences de tels systèmes dans la nature,par exemple sous la forme de sable ou d'une chevelure humaine ;aussi la reproduction numérique de leur dynamique trouve des applications diverses, allant de considérations géotechniques à la production d'effets spéciaux réalistes pour le cinéma.Une difficulté majeure pour la simulation de tels systèmes concerne la non-régularité de leur dynamique ; à une échelle de temps macroscopique, on observe par exemple des sauts dans les vitesses des constituants lors d'impacts.La première partie de ce manuscrit est ainsi dédiée à la conception d'algorithmes efficaces permettant de prendre en compte les contacts avec frottement de Coulomblors de la simulation de systèmes mécaniques discrets. La méthode que nous proposons, basée sur un algorithme de type Gauss--Seidel avec stratégie hybride, s'avèrerobuste et perfomante sur le problème délicat de la simulation virtuelle de chevelures.La second partie de ce manuscrit est consacrée à l'étude de systèmes à une échelle beaucoup plus grande, au delà du million de grains. Puisque le calcul de toutes les forces de contacts pour chaque paire de grains s'avérerait trop coûteux, on adopte un point de vue macroscopique en utilisant le formalisme des milieux continus. On propose ainsi d'adapter les méthodes développées pour la simulation de systèmes discrets à la résolution de la rhéologie dite de Drucker--Prager, une relation entre la contrainte et le cisaillement du matériau exprimant l'influence moyennée des forces de frottement.On montre que cette approche nous permet de retrouver le comportement qualitatif de matériaux granulaires secs observé expérimentalement.Finalement, nous proposons un nouveau modèle numérique pour l'étudedes dynamiques couplées d'un matériau granulaire immergé dans un fluide Newtonien,et montrons une nouvelle fois que les algorithmes développés pour la mécanique discrètes'avèrent également pertinents dans le cas continu. / This dissertation focuses on the numerical simulation of mechanical systems consisting of a large number of discrete pieces interacting with each other through contacts and dry friction. Examples of such systems --- for instance, sand or human hair --- are common in natural environments; being able to predict their dynamics is therefore of great importance for diverse applications ranging from geotechnical considerations to engaging visual effects for feature films.A major difficulty that complicates the numerical simulation of such complex systems stems from the nonsmoothness of their dynamics. For instance, from a macroscopic viewpoint, the velocity of the individual constituents may exhibit instantaneous jumps when impacts occur.The first part of this manuscript will be dedicated to the establishment of efficient algorithms for the numerical simulation of discrete mechanical systems subject to contacts and Coulomb friction. We advocate using a Gauss--Seidel algorithm with a hybrid local solver, and show that this strategy performs robustly in the challenging context of virtual hair simulation.The second part of this dissertation will focus on much bigger systems, consisting of millions or billions of grains.As computing every force between pairs of contacting grains quickly becomes intractable, we embrace a continuum viewpoint instead. We show how the numerical methods devised for the simulation of discrete mechanical systems can be adapted to thesimulation of flows governed by the Drucker--Prager rheology --- a constitutive relationship between the material's stress and strain rate that macroscopically models the action of frictional contact forces. This approach allows us to capture qualitative features of granular flows that have been observed experimentally. Finally, we propose a new numerical model for the coupled simulation of a granular continuum with a surrounding fluid, and show that once again, we are able to leverage efficient algorithms from discrete contact mechanics to solve the resulting equations.

Enhancement of mechanical, thermal and hygrothermal properties of carbon fiber/vinyl ester (CFVE) composites through nanoparticle reinforcement has been investigated. CFVE composites are becoming more and more attractive for marine applications due to two reasons : high specific strength and modulus of carbon fiber and low vulnerability of vinyl ester resin to sea water. However, the problem with this composite system is that the fiber matrix (F/M) interface is inherently weak. This leads to poor mechanical properties and fast ingress of water at the interface further deteriorating the properties. This investigation attempts to address these deficiencies by inclusion of nanoparticles in CFVE composites. Three routes of nanoparticle reinforcement have been considered : nanoparticle coating of the carbon fiber, dispersion of nanoparticles in the vinyl ester matrix, and nanoparticle modification of both the fiber and the matrix. Flexural, short beam shear and tensile testing was conducted after exposure to dry and wet environments. Differential scanning calorimetry and dynamic mechanical analysis were conducted as well. Mechanical and thermal tests show that single inclusion of nanoparticles on the fiber or in the matrix increases carbon/vinyl ester composite properties by 11-35%. However, when both fiber and matrix were modified with nanoparticles, there was a loss of properties. / by Felicia M. Powell. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

This study focused on the fracture and fatigue crack growth behavior in polyvinylchloride (PVC) and polyethersulfone (PES) foams. A new sandwich double cantilever beam (DCB) test specimen was implemented. Elastic foundation and finite element analysis and experimental testing confirmed that the DCB specimen is appropriate for static and cyclic crack propagation testing of soft polymer foams. A comprehensive experimental mechanical analysis was conducted on PVC foams of densities ranging from 45 to 100 kg/m3 and PES foams of densities ranging from 60 to 130 kg/m3. An in-situ scanning electron microscope study on miniature foam fracture specimens showed that crack propagation in the PVC foam was inter-cellular and in the PES foam, failure occurred predominately by extensional failure of vertical cell edges. Sandwich DCB specimens were loaded cyclically as well. For the PVC foams, the crack growth rates were substantially influenced by the density. For the PES foams, there was no clear indication about the influence of foam density on the crack growth rate. / by Elio Saenz. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

In fabrication of nanoparticle-reinforced polymers, two critical factors need to be taken into account to control properties of the final product; nanoparticle dispersion/distribution in the matrix; and interfacial interactions between nanoparticles and their surrounding matrix. The focus of this thesis was to examine the role of these two factors through experimental methodologies and molecular-level simulations. Carbon nanotubes (CNTs) and vinyl ester (VE) resin were used as nanoparticles and matrix, respectively. In a parametric study, a series of CNT/VE nanocomposites with different CNT dispersion conditions were fabricated using the ultrasonication mixing method. Thermomechanical properties of nanocomposites and quality of CNT dispersion were evaluated. By correlation between nanocomposite behavior and CNT dispersion, a thermomechanical model was suggested; at a certain threshold level of sonication energy, CNT dispersion would be optimal and result in maximum enhancement in properties. This threshold energy level is also related to particle concentration. Sonication above this threshold level, leads to destruction of nanotubes and renders a negative effect on the properties of nanocomposites. In an attempt to examine the interface condition, a novel process was developed to modify CNT surface with polyhedral oligomeric silsesquioxane (POSS). In this process, a chemical reaction was allowed to occur between CNTs and POSS in the presence of an effective catalyst. The functionalized CNTs were characterized using TEM, SEM-EDS, AFM, TGA, FTIR and Raman spectroscopy techniques. Formation of amide bonds between POSS and nanotubes was established and verified. Surface modification of CNTs with POSS resulted in significant improvement in nanotube dispersion. In-depth SEM analysis revealed formation of a 3D network of well-dispersed CNTs with POSS connections to the polymer. In parallel, molecular dynamics simulation of CNT-POSS/VE system showed an effective load transfer from polymer chains to the CNT due to POSS linkages at the interface. The rigid and flexible network of CNTs is found to be responsible for enhancement in elastic modulus, strength, fracture toughness and glass transition temperature (Tg) of the final nanocomposites. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

The tensile strength of the fiber/matrix interface was determined through the development of an innovativetest procedure.Aminiature tensile coupon with a through-thickness oriented, embedded single fiberwas designed. Tensile testing was conducted ina scanning electron microscope (SEM)while the failure process could be observed.Finite element stress analysis was conducted to determine the state of stressat the fiber/matrix interface in the tensile loaded specimen, and the strength of the interface.Test specimensconsistingof dry E-glass/epoxy and dry and seawater saturatedcarbon/vinylester510Awere preparedand tested.The load at the onset of debondingwascombined withthe radial stressdistributionnear thefree surface of the specimento reducethe interfacial tensile strength. For glass/epoxy, was 36.7±8.8MPa.For the dryand seawater saturated carbon/vinylester specimensthetensilestrengthsof the interface were 23.0±6.6 and 25.2±4.1MPa, respectively.The difference is not significant. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Ces travaux ont pour objet l’élaboration de nouvelles structures poreuses non tissées antibactériennes. Différentes stratégies ont été développées : l’une a consisté à élaborer des mats poreux par electrospinning en utilisant un polymère biosourcé et biocompatible et l’autre voie consistait à modifier un support fibreux provenant d’un masque de protection respiratoire commercial. La méthode des assemblages par interactions ioniques en superposant de façon alternative les couches de polymères cationiques et les polymères anioniques à la surface du filtre médian en polypropylène (PP) a permis d’élaborer de nouvelles structures ayant de bonnes propriétés antioxydantes et antibactériennes. Le polymère anionique, dérivé du polymère de cyclodextrine présente l’avantage de pouvoir encapsuler un agent antimicrobien biosourcé, le carvacrol. Une autre approche a consisté à modifier des supports en PP avec de l'acide tannique, un polyphénol d'origine naturelle. Dans cette étude, deux stratégies ont été mises en place afin de fonctionnaliser le PP avec de l’acide tannique (AT). La première est l’extrusion réactive du PP avec l’AT en présence (ou non) de peroxyde de dicumyle (DCP) pour greffer directement l’acide tannique sur le PP. La deuxième stratégie consiste à polymériser l’AT au travers d’une couche poreuse de PP extraite d’un masque de protection commercial, afin de permettre l’immobilisation physique de l’AT à la surface du mat fibreux en PP. Le greffage en surface via un procédé “grafting from” a également été étudié. Ces matériaux ont montré de bonnes propriétés antiradicalaires. / The purpose of this work is to develop new antibacterial non-woven porous structures. Different strategies were developed: one was to develop porous structures by electrospinning using a biosourced and biocompatible polymer, the other was to modify a fibrous support from a commercial respiratory protection mask. Assembling materials using ionic interactions by alternatively superposing cationic polymer layers and anionic polymers on the surface of the polypropylene (PP) median filter allowed to develop new structures with good antioxidant and antibacterial properties. The anionic polymer, derived from the cyclodextrin polymer, has the advantage of being able to encapsulate a bio-based antimicrobial agent, carvacrol. Another approach was to modify PP filters with tannic acid, a naturally occurring polyphenol. In this study, two strategies were implemented to functionalize PP with tannic acid (TA). The first is the reactive extrusion of PP with TA in the presence (or not) of dicumyl peroxide (DCP) to directly graft tannic acid onto PP. The second strategy consists in polymerizing the TA through a porous layer of PP extracted from a commercial mask, in order to allow the physical immobilization of the TA on the surface of the PP fibrous mat. Surface grafting using a "grafting from" process was also studied. These materials have shown good anti-free radical properties.

The effective radiative conductivity of fibrous material is an important part of the evaluation of the thermal performance of fibrous insulators. To better evaluate this material property, a three-dimensional direct simulation model which calculates the effective radiative conductivity of fibrous material is proposed. Two different geometries are used in this analysis. The simplified model assumes that the fibers are in a cylindrical shape and does not require identically-sized fibers or a symmetric configuration. Using a geometry with properties resembling those of a fibrous insulator, a numerical calculation of the geometric configuration factor is carried out. The results show the dependency of thermal conductivity on temperature as well as the orientation of the fibers. The calculated conductivity values are also used in the continuum heat equation, and the results are compared to the ones obtained using the direct simulation approach, showing a good agreement. In continue, the simulated model is replaced by a realistic geometry obtained from X-ray micro-tomography. To study the radiative heat transfer mechanism of fibrous carbon, three-dimensional direct simulation modeling is performed. A polygonal mesh computed from tomography is used to study the effect of pore geometry on the overall radiative heat transfer performance of fibrous insulators. An robust procedure is presented for numerical calculation of the geometric configuration factor to study energy-exchange processes among small surface areas of the polygonal mesh. The methodology presented here can be applied to obtain accurate values of the effective conductivity, thereby increasing the fidelity in heat transfer analysis.