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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Avaliação por microtomografia de raio-X do reparo ósseo em osteotomia completa de tíbia de ratos após tratamento com ultrassom de baixa intensidade e laser de baixa potência / Assessment of bone repair by x-ray microtomography in complete Tiba rats osteotomy after low-intensity pulsed ultrasound and low-level laser therapy

Alessandra Rossi Paolillo 12 December 2013 (has links)
As fraturas são consideradas um dos maiores problemas de saúde pública pelo custo e morbidade a elas associados. O objetivo deste estudo foi investigar os efeitos do ultrassom de baixa intensidade (LIPUS) e do laser de baixa potência (LLLT) sobre o reparo ósseo de tíbia de ratos (Wistar) utilizando a microtomografia por raio-x (&#956CT) e a análise histomorfométrica. Uma osteotomia total no terço médio foi fixada com fio de Kirschner (0,89 mm) e utilizado um espaçador polimérico de 2 mm de espessura e 1 mm de diâmetro entre os fragmentos proximal e distal para induzir retardo de consolidação da fratura. Foram utilizados 24 animais separados aleatoriamente em 4 grupos experimentais: Grupo Controle: sem tratamento do retardo da consolidação (n = 5); Grupo Laser: tratamento da fratura com laser (n = 6); Grupo LIPUS: tratamento da fratura com LIPUS (n = 7) e; Grupo LIPUS + Laser: tratamento da fratura com LIPUS e Laser (n = 7). Os tratamentos com LIPUS e/ou Laser foram iniciados após 5 semanas da cirurgia e realizados durante 5 dias consecutivos de tratamento, seguidos por 2 dias sem serem tratados até totalizarem 12 sessões terapêuticas. Os parâmetros de irradiação laser foram: 808 nm; 100 mW; 2500 mW/cm² , 125 J/cm² durante 50 segundos. Os parâmetros do LIPUS foram: 1,5 MHz, ciclo de trabalho 1:4, intensidade de 30 mW/cm², 20 minutos por sessão. Quando as duas técnicas foram associadas, o laser foi aplicado perpendicularmente ao LIPUS no décimo minuto de aplicação do LIPUS. Radiografias da tíbia foram feitas para acompanhar a evolução da fratura após a cirurgia, antes dos tratamentos e antes da eutanásia. Após a eutanásia foram realizadas avaliações microtomográficas por raio-x e histomorfométricas para análise do reparo ósseo. Na análise microtomográfica do reparo ósseo o tecido neoformado de reparo (calo ósseo) e o tecido normal não foram isolados. Na análise estatística foi utilizada a ANOVA one-way com posthoc de Tukey. Não foi constatada diferença significativa para maioria das variáveis, exceto para o fator padrão trabecular (Tb.Pf) no grupo LIPUS+Laser comparado aos grupos LIPUS (p = 0.02), Laser (p = 0.02) e Controle (p = 0.01), para a conectividade (Conn) no grupo Laser comparada ao grupo Controle (p = 0.04) e para a densidade de conectividade (D.Conn) no grupo LIPUS+Laser comparado ao grupo Controle (p = 0.04). As imagens histológicas mostram maior quantidade de tecido esponjoso no grupo LIPUS+Laser. Parâmetros morfométricos e histomorfométricos não revelaram um avanço do reparo ósseo na comparação entre os grupos com tratamento em relação ao grupo controle provavelmente devido a não reabsorção do espaçador polimérico pelo organismo dos animais. A &#956CT é uma técnica de grande potencial que permite análises qualitativas e quantitativas e reconstruçoes 2D e 3D. / Bone fractures are important public health problems due to the morbidity and high cost related to them. The aim of this study was to evaluate the effects of low pulsed intensity ultrasound (LIPUS) and infrared low level laser therapy (LLLT) in the bone repair of a transverse rat tibia osteotomy with assessement by x-ray microtomography (&#956CT) and histomorphometry. An easily implemented transverse osteotomy with a Kirchner wire and 2 mm width polymeric spacer beads established a delayed union in the fracture. Twenty four rats were divided into four experimental groups: Control Group - untreated; Laser Group - treated with infrared LLLT; LIPUS Group treated with low intensity pulsed ultrasound; LIPUS+Laser Group - treated with low intensity pulsed ultrasound and infrared LLLT. The treatments with infrared LLLT (808 nm, 100 mW, 2500 mW/cm², 125 J/cm², 50 seconds) and LIPUS (1,5 MHz, 1:4 duty cicle, 30 mW/cm², 20 minutes) started 5 weeks after the surgery following a sequence of 5 days on and 2 days off until 12 sessions were reached. When LLLT and LIPUS therapies were used simultaneously there was a 90º angle between the laser and the ultrasound beams. The surgical technique and the bone repair were assessed by x-ray radiography. One-way analysis of variance (one-way ANOVA) and Tukey post-hoc were used for statistical analysis. The normal bone and the callus were kept together in the &#956CT analysis. There was no significant difference between treatments results except for the parameters trabecular pattern factor - Tb.Pf [US+Laser group x LIPUS group (p = 0.02); US+Laser group x Laser group (p = 0.02) and US+Laser group x Control group (p = 0.01)], connectivity - Conn [Laser group x Control group (p = 0.04)] and connectivity density D.Conn [US+Laser group x Control group (p = 0.04)]. The histology showed greater amount of spongeous bone in the LIPUS+Laser group. The morphometric and histomorphometric assessments didn´t show a faster bone repair when treated groups were compared against the control one. The non absorption of the polymeric spacer bead is probably the reason of these findings. The &#956CT is a powerful technique that allows 2D and 3D quantitative analysis and reconstructions.
132

Vyhodnocení ošetření zubních kanálků pomocí rentgenové počítačové mikrotomografie / Evaluation of dental pulp treatment based on the X-ray micro computed tomography

Břínek, Adam January 2016 (has links)
This work deals with processing and analysis of micro-CT images of dental-canals filled by~two materials (AH-plus and NaMPC). For that reason, six dog-teeth were scanned in the X-Ray Micro CT Research Lab. The main aim was to produce an algorithm (in Matlab) that evaluates the quality of filling of dental canals (quality of filling materials). The algorithm performs the segmentation of dental canals and calculates their borders. Also, the algorithm measures the percentage contacts of filling materials with dental walls. Moreover, the algorithm provides masks of dental canals according to requirements of the commercial program VG Studio, that evaluates the porosity of filling materials. The results of percentage contacts and porosities show on not-remarkable differences of tested filling materials.
133

Análise do preparo, limpeza, desinfecção e obturação de canais radiculares de molares inferiores por diferentes protocolos e materiais /

João, Mariana Mena Barreto Pivoto January 2019 (has links)
Orientador: Juliane Maria Guerreiro Tanomaru / Resumo: Este estudo avaliou o preparo, limpeza e obturação de canais radiculares de molares inferiores por diferentes protocolos e materiais. Canais mesiais (n=48) de molares inferiores curvos (20°- 40°) foram preparados usando ProDesign Logic (PDL) até 25/.06 ou HyFlex EDM (HFEDM) 25/.08, e até PDL-40/.05 ou HFEDM-40/.04 na ampliação (Publicação 1). A irrigação final foi realizada com irrigação ultrassônica passiva-PUI ou easy clean-EC, hipoclorito de Sódio-NaOCl ou clorexidina-CLX ou água destilada (n=8): PUI/NaOCl2,5%; EC/NaOCl2,5%; EC/água destilada; PUI/CLX 2%; PUI/NaOCl 1%; PUI/NaOCl 2,5% (Publicação 2). A obturação foi realizada por condensação lateral-CL ou Termo Pack II e AHP (Publicação 3); cone único (CU) com nMTAP ou TFBC (Publicação 4). Escaneamentos (9 μm) foram realizados antes e após cada etapa experimental. Percentual de aumento volumétrico (%AV), debris (%D), redução de debris (%RD), superfície não instrumentada (%SNI), centralização, material obturador (%MO) e falhas (%F) foram analisados em toda a extensão do canal (total) e nos terços dos canais radiculares. Testes ANOVA e Tukey ou Kruskal-Wallis e Dunn, e T Pareado foram realizados (α = 0,05). HFEDM-25/.08 promoveu maior % AV. Após a dilatação, HFEDM apresentou maior volume (P < 0,05) e houve redução de %D e %SNI. Os sistemas produziram canais centralizados (Publicação 1). Houve diminuição do percentual e volume de debris acumulados após as técnicas e entre o PUI com diferentes soluções irrigantes. EC/NaOCl prop... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor
134

Preparo e obturação de canais distais achatados de molares inferiores : análise por microtomografia computadorizada /

Santos Júnior, Airton Oliveira. January 2020 (has links)
Orientador: Juliane Maria Guerreiro Tanomaru / Resumo: Objetivo: Avaliar o preparo com instrumentos de níquel-titânio tratados termicamente em movimento rotatório ou reciprocante e a associação com inserto ultrassônico e capacidade de preenchimento pelas técnicas híbrida de Tagger ou cone único empregando o cimento Bio-C Sealer em canais radiculares achatados. Metodologia: Canais distais achatados de molares inferiores com diâmetro vestíbulo-lingual igual ou maior que 4 vezes o diâmetro mésio-distal foram preparados (n=12) por Reciproc Blue (RB) R40 em movimento reciprocante ou ProDesign Logic (PDL) 40.01 e 40.05 em movimento rotatório. Etapa complementar de instrumentação foi realizada com inserto ultrassônico Flatsonic nos dois grupos. Os canais foram obturados (n=12) pela técnica híbrida de Tagger ou cone único com o cimento Bio-C Sealer. Escaneamentos em resolução de 8,74 µm foram realizados em microtomografia computadorizada (micro-CT) antes e após todas as etapas experimentais. Percentual de aumento volumétrico, debris e superfície não instrumentada foram analisados para as etapas de preparo e percentual de falhas para obturação. Testes estatísticos ANOVA e Tukey, teste t pareado e não pareado foram realizados com nível de significância de 5%. Publicação 1 – Resultados: O percentual de aumento volumétrico, debris e superfície não instrumentada foi semelhante entre RB e PDL na extensão total do canal (P>0,05). PDL promoveu menor percentual de debris no terço cervical e menor percentual de aumento volumétrico no terço apical ... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre
135

Análise por microtomografia computadorizada do preparo e obturação de canais radiculares achatados de segundos pré-molares superiores /

Tavares, Karina Ines Medina Carita. January 2020 (has links)
Orientador: Mario Tanomaru Filho / Resumo: Objetivo: Avaliar o preparo empregando dois sistemas rotatórios de níquel-titânio tratados termicamente e efeito do novo inserto ultrassônico e instrumento de menor diâmetro e a capacidade de preenchimento dos cimentos Bio-C Sealer ou AH Plus pela técnica de cone único em canais radiculares achatados de segundos pré-molares superiores. Metodologia: Canais radiculares achatados de segundos pré-molares superiores humanos com diâmetro vestíbulo-lingual igual ou maior que 4 vezes o diâmetro mésio-distal foram preparados com sistemas rotatórios(n=16): ProDesign Logic (PDL) 30.01 e 30.05 ou HyFlex EDM (HEDM) 10.05 e 25.08. Etapa do preparo complementar foi realizada com inserto ultrassônico Flatsonic (terço cervical e médio) e PDL 25.03 (terço apical) (FPDL) em ambos os grupos. Os canais radiculares foram obturados (n=16) com o cimento Bio-C Sealer ou AH Plus pela técnica de cone único. Escaneamentos em resolução de 8,74 µm foram realizados em microtomografia computadorizada (micro-CT) antes e após as etapas experimentais. Percentual de aumento volumétrico, debris e superfície não instrumentada foram analisados para as etapas de preparo e percentual de falhas para obturação. Os testes estatísticos específicos para o preparo e obturação foram realizados com nível de significância de 5%. Publicação 1 – Resultados: Não houve diferença estatística entre PDL e HEDM para o aumento de volume, debris e superfície não instrumentada no canal como um todo (P>0,05). PDL obteve maior percentual... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Objective: The aim of this study was to evaluate root canal preparation using two rotary nickel-titanium systems thermally treated and the effect of ultrasonic tip and small diameter instrument; and the filling capacity of sealers Bio-C Sealer and AH Plus by single cone technique in flattened root canals of maxillary second premolars. Methods: Flattened root canals of human maxillary second premolars with buccolingual diameter 4 or more times larger than the mesiodistal diameter were prepared with rotary systems (n=16): ProDesign Logic (PDL) 30.01 e 30.05 or HyFlex EDM (HEDM) 10.05 e 25.08. Complementary preparation step was performed with ultrasonic tip Flatsonic (cervical and middle thirds) and PDL 25.03 (apical third) (FPDL) in both groups. The root canals were filled (n=16) with Bio-C Sealer or AH Plus by single cone technique. Scanning in resolution of 8,74 µm were performed by microcomputed tomography (micro-CT) before and after the experimental steps. Percentage of increase in volume, debris and uninstrumented surface were analysed for the preparation steps and percentage of voids for obturation. The statistical tests specific to preparation and obturation analyses were performed with a significance level of 5%. Publication 1 - Results: There was no statistically difference between PDL and HEDM for volume increase, debris and uninstrumented surface, in entire canal (P>0,05). PDL showed higher debris in the middle and apical thirds than HEDM (P<0,05). The FPDL protocol ... (Complete abstract click electronic access below) / Mestre
136

Micromechanics of Fiber Networks

Borodulina, Svetlana January 2016 (has links)
The current trends in papermaking involve, but are not limited to, maintaining the dry strength of paper material at a reduced cost. Since any small changes in the process affect several factors at once, it is difficult to relate the exact impact of these changes promptly. Hence, the detailed models of the network level of a dry sheet have to be studied extensively in order to attain the infinitesimal changes in the final product. In Paper A, we have investigated a relation between micromechanical processes and the stress–strain curve of a dry fiber network during tensile loading. The impact of “non-traditional” bonding parameters, such as compliance of bonding regions, work of separation and the actual number of effective bonds, is discussed. In Paper B, we studied the impact of the chemical composition of the fiber cell wall, as well as its geometrical properties, on the fiber mechanical properties using the three-dimensional model of a fiber with helical orientation of microfibrils at a range of different microfibril angles (MFA). In order to accurately characterize the fiber and bond properties inside the network, via statistical distributions, microtomography studies on the handsheets have been carried out. This work is divided into two parts: Paper C, which describes the methods of data acquisition and Paper D, where we discuss the extracted data. Here, all measurements were performed at a fiber level, providing data on the fiber width distribution, width-to-height ratio of isotropically oriented fibers and contact density. In the last paper, we utilize data thus obtained in conjunction with fiber morphology data from Papers C and D to update the network generation algorithm in order to produce more realistic fiber networks. We also successfully verified the models with the help of experimental results from dry sheets tested under uniaxial tensile tests. We carry out numerical simulations on these networks to ascertain the influence of fiber and bond parameters on the network strength properties. / <p>QC 20160613</p>
137

Microtomographie X de matériaux à comportement pseudo-fragile : Identification du réseau de fissures / X-ray microtomography of materials to brittle-like behavior : Identification of the crack network

Hauss, Grégory 06 December 2012 (has links)
L'étude de l'endommagement des matériaux à comportement pseudo-fragile fait l'objet denombreuses études et la caractérisation du réseau de fissures constitue une étape nécessairepour une meilleure compréhension de leur comportement. L'objectif principal est ici d'identifierde manière la plus fine possible cet espace fissuré en trois dimensions grâce à la techniqued'imagerie nommée microtomographie X. Pour ce faire, une machine d'essai in-situ a étédéveloppée et une procédure d'analyse des images 3D a été validée. L'objectif du dispositif insituest de maintenir l'échantillon dans différents états fissurés pour rendre possible lesacquisitions microtomographiques. Une fois les images 3D reconstruites, la procédure detraitement est appliquée et l'espace fissuré est identifié. Des mesures sont alors réalisées surl'évolution du réseau de fissures au cours de l'endommagement. Ce travail constitue la premièreétape d'un traitement plus général qui a pour objectif de simuler numériquement lecomportement mécanique de ces matériaux en se basant sur leur géométrie réelle. / Materials displaying a pseudo-brittle behavior have been well studied over the past decade andthe characterization of the cracks network has become nowadays an important step for theunderstanding of their damaging behavior. The aim of this work is to characterize, in the finestavailable way, this crack space in 3D using X-ray computed microtomography. This wasachieved: 1) by designing an in-situ compressive device which maintains a sample in a crackedstate during microtomographic data acquisition and, 2) by processing the images with relevantimage filtering techniques for a better cracks network characterization. Two parameters ofchoice are then measured: the cracks network surface and volume. This work is the first step ofa global procedure which aims to numerically model the mechanical behavior of pseudo-brittlematerials by using real 3D crack geometry.
138

Caractérisation des changements dans les propriétés de réservoir carbonaté induits par une modification dans la structure des pores lors d'une injection de CO2 : application au stockage géologique de CO2 / Experimental characterization of the change in hydrodynamic properties induced during carbonate dissolution with water enriched in CO2

Mangane, Papa Ousmane 25 June 2013 (has links)
Le stockage géologique du CO2 est l'une des diverses technologies étant explorées afin de réduire les émissions de carbone atmosphérique des processus industriels (i.e. combustion de l'énergie fossile). L'une des spécifiques caractéristiques de l'injection du CO2 en profondeur reste la possibilité de réactions géochimiques (dissolution-précipitation) entre la saumure réactive mobile (e.g. eau de formation enrichie en CO2) et la roche encaissante durant l'évolution spatiale et temporelle du CO2, conduisant à des modifications dans la structure des pores et par conséquent dans les propriétés d'écoulement du réservoir (e.g. la perméabilité k). Donc, ces changements structuraux peuvent largement contrôler l'injectivité, ainsi que le champ de pression dans le réservoir et aussi la propagation du CO2. Il demeure ainsi crucial d'explorer les changement dans les propriétés de réservoirs (e.g. structurales et hydrodynamiques) induits durant une injection de CO2 et explicitement les relations existantes entre eux (e.g. k ou surface réactive-Sr versus porosité- , k versus hétérogénéité de la roche), afin de développer des outils de modélisation prédictive des processus de transport et réactionnels se produisant durant une injection de CO2 et d'évaluer de façon fiable les risques. Dans le cas des réservoirs carbonatés, l'application des modèles prédictifs de transport réactif demeure toujours un enjeu, car contrainte par la forte hétérogénéité en leur sein ainsi que par l'incertitude dans la cinétique de réactions des minéraux carbonatés dans ce contexte. Dans cette optique, nous avons réalisé des expériences de percolation à travers des échantillons de roches carbonatées dans les conditions thermodynamiques de stockage en profondeur (T = 100°C et P =12 MPa). L'évolution de la perméabilité est suivie au cours des expériences ; et la variation de la porosité est calculée à partir des résultats d'analyses chimiques au ICP-AES des fluides de sortie échantillonnés. L'investigation des modifications apportées à la structure des pores est réalisée par le biais de la Micro-Tomographie haute résolution à rayon X, acquise au synchrotron de Grenoble (e.g. ESRF). Dépendant du régime de dissolution, contrôlé par la fabrique de la roche réservoir et la composition chimique de la saumuré chargée en CO2 (e.g. PCO2 engagée), on a observé qu'une modification de la structure de la roche peut soit améliorer soit détériorer (résultat atypique en contexte de dissolution) la valeur de la perméabilité k. Mots clés : Stockage géologique du CO2, transport, réactions géochimiques, structure des pores, propriétés hydrodynamiques, expériences de percolation de CO2, micro-tomographie à rayon X. / Geological storage of CO2 is one of diverse technologies being explored to reduce atmospheric carbon from industrial processes (i.e. fossil fuel combustion). One of the specific features of CO2 injection is the possibility of geochemical reactions (dissolution – precipitation) between mobile reactive brine (e.g. formation water enriched in CO2) and the host rock during the spatial and temporal evolution of CO2. That leads to modifications in the pore structure which in turn change the flow dynamics of the reservoir (e.g. the permeability k). Then, theses structural modifications can largely control the injectivity, so that the pressure field in the reservoir and also the CO2 propagation. Accordingly, it is crucial to explore the changes in the reservoir properties (e.g. structural and hydrodynamic) induced during a CO2 injection and specially the relationships between them (e.g. k or reactive surface-Sr versus porosity- , k versus rock heterogeneity), for developing predictive modelling tools of the transport and reaction processes occurring during a CO2 injection and reliable risk assessment. In the case of carbonate rocks, the application of the predictive models of transport and reaction is still challenging, because of their high heterogeneity so that the incertitude in the reaction kinetics of carbonate minerals. From this perspective, we realized brine-enriched in CO2 percolation experiments through carbonate rock samples in thermodynamic conditions expected during CO2 injection in deep reservoirs (T = 100°C et P =12 MPa). The permeability changes k(t) is monitored during the experiments and the porosity variation is calculated from chemical analyses of the sampled outlet fluids, using ICP-EAS. The pore structure modifications are investigated from high resolution X ray micro tomography images acquired from the synchrotron of Grenoble (ESRF). Depending to the dissolution regime, controlled by the reservoir rock fabric and the chemical composition of the brine (e.g. PCO2), we observed that a modification of pore structure can either improve (atypical result in dissolution context) or impair the value of the permeability k. Keywords: CO2 geological storage, transport, geochemical reactions, pore structure, hydrodynamic properties, brine enriched in CO2 percolation experiments, X ray microtomography.
139

Simulation numérique directe multiphasique de la déformation d’un alliage Al-Cu à l’état pâteux – Comparaison avec des observations par tomographie aux rayons X in situ en temps réel / Direct and multiphase numerical simulation of the Al-Cu alloy deformation in the mushy state – Comparison with in situ and real-time X-ray tomography observations

Zaragoci, Jean-François 09 July 2012 (has links)
La fissuration à chaud est un défaut majeur rencontré en solidification des alliages d'aluminium. Elle est liée à l'incapacité du liquide de s'écouler dans les zones où des porosités sont présentes, ne permettant pas de les refermer avant qu'elles gagnent en volume. Pour comprendre la fissuration à chaud, il est crucial de développer nos connaissances du comportement mécanique de la zone pâteuse. Pour cela, il est très utile d'effectuer des expériences de microtomographie aux rayons X et des simulations mécaniques sur des volumes élémentaires représentatifs. Dans cette thèse, nous proposons de coupler les deux approches en initialisant une simulation par éléments finis grâce à des données de microtomographie issues d'un test de traction isotherme d'un alliage d'aluminium-cuivre à l'état pâteux. Cette approche originale nous donne directement accès à la réalité expérimentale et permet des comparaisons des évolutions numérique et expérimentale de l'éprouvette. Nous expliquons dans un premier temps comment obtenir la représentation numérique à l'aide de l'algorithme des marching cubes et de la méthode d'immersion de volume. Nous présentons ensuite notre modèle numérique qui s'appuie sur une résolution monolithique des équations de Stokes. Une fois le champ de vitesse obtenu dans l'ensemble des phases solide, liquide et gazeuse, nous utilisons une méthode level set dans un formalisme eulérien afin de faire évoluer la morphologie de notre échantillon numérique. Malgré la simplicité du modèle, les résultats expérimentaux et numériques montrent un accord raisonnable en ce qui concerne la propagation de l'air à l'intérieur de l'échantillon. / Hot tearing is a major defect arising during solidification of aluminium alloys. This defect is associated with the inability of liquid to feed areas where voids have started to appear, not allowing to heal small defects before they grow bigger. To understand hot tearing, it is mandatory to develop a good knowledge of the semi-solid mechanical behaviour. It is thus very useful to carry out X-ray microtomographies experiments and mechanical simulations on representative elementary volumes. In this work, we couple the both approaches by initialising a finite element simulation with the help of microtomography data obtained during an isothermal tensile testing of an aluminium-copper alloy in the mushy state. This innovative approach gives a direct access to the experimental reality and allows comparisons of numerical and experimental evolutions of the sample. We explain in a first time how to get the numerical representation thanks to a marching cubes algorithm and the immersed volume method. Then, we present our numerical model for which we solve the Stokes equations in a monolithic way. Once the velocity computed in all the solid, liquid and gaseous phases, we use a level set method in a Eulerian formalism to obtain the morphological evolution of our numerical sample. Despite the model simplicity, numerical and experimental results show a reasonable agreement concerning the air propagation inside the sample.
140

Efeito da membrana de poli (vinilideno-trifluoretileno)/titanato de bário no reparo de defeitos ósseos em calvárias de ratas ovariectomizadas / Effect of poly (vinylidene-trifluoroethylene)/barium titanate membrane on the repair of bone defects in calvaria of ovariectomized rats

Scalize, Priscilla Hakime 06 April 2018 (has links)
O aumento da longevidade da população mundial vem acompanhado do aumento da incidência de doenças crônicas. Várias são as doenças que podem acometer esta população e entre estas, a osteoporose, que compromete a resistência e qualidade do tecido ósseo, predispondo a fraturas. Além disso, a osteoporose pode dificultar a reparação óssea. Uma técnica importante e que tem por objetivo a neoformação óssea é a regeneração óssea guiada (ROG), que utiliza uma membrana que atua como uma barreira mecânica, permitindo a criação de um espaço protegido em torno do defeito ósseo. Embora a membrana de politetrafluoretileno (PTFE) seja uma das mais utilizadas na ROG, novas membranas têm sido desenvolvidas dentre elas a membrana obtida pela associação do polímero de poli(vinilideno-trifluoretileno) e da cerâmica de titanato de bário (P(VDF-TrFE)/BT). Estudos in vitro demonstraram resultados favoráveis à membrana de P(VDF-TrFE)/BT. Desta forma, o objetivo deste estudo foi avaliar in vivo, o efeito da membrana de poli(vinilidenotrifluoretileno)/titanato de bário (P(VDF-TrFE)/BT), e como controle a de PTFE no reparo ósseo em ratas com modelo experimental para a osteoporose. Foram utilizados 30 animais, sendo 5 pertencentes ao grupo controle - Grupo 1 (G1) e 25 que foram ovariectomizados bilateralmente (OVX). Após 150 dias foram confeccionados defeitos ósseos (5 mm) na calvária e os animais OVX foram distribuídos em três grupos com relação à utilização ou não de membranas nos defeitos ósseos: Grupo 2 - nenhum tipo de membrana; Grupo 3 - membrana de PTFE e Grupo 4 - membrana de P(VDF-TrFE)/BT. Após 4 semanas, os animais foram eutanasiados e as calvárias foram coletadas para as análises histológica, histomorfométrica por micro-CT e de expressão gênica por PCR em tempo real. A análise histomorfométrica mostrou que os animais que receberam a membrana de P(VDF-TrFE)/BT apresentaram parâmetros morfométricos semelhantes ou até melhores quando comparados com os animais que receberam a membrana de PTFE. A comparação dos grupos que receberam as membranas mostrou para o grupo P(VDF-TrFE)/BT uma menor expressão para os genes RUNX2, BSP, OPN, OSX e RANKL; uma expressão semelhante para os genes ALP, OC, RANK e CTSK e uma maior expressão dos genes OPG, CALCR e MMP9. Estes resultados evidenciam que a membrana de P(VDF-TrFE)/BT pode ser considerada um biomaterial promissor para a reparação óssea em condições de osteoporose / The worldwide population age is increasing accomplished by chronic disease. The most common disease which involves the population is the osteoporosis. The bone resistance and quality of bone matrix are compromised and the fractures risks are higher. Nonetheless, the osteoporosis can avoid the bone healing. The important technique to achieve the bone neoformation is the Bone Guided Regeneration (BGR), which used a membrane as mechanic barrier to allow the new gap protection around the bone defect. Although the politetrafluoetilene (PTFE) is the most used in BGR, newest membranes have been developed as the polyvinylidene-trifluoroethylene polymer and barium titanate ceramics (P(VDF-TrFE)/BT). In vitro assays showed favorable results to P(VDF-TrFE)/BT membrane. The aim of the study was to evaluate the poly(vinylidene fluoride-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT) effects, and the PTFE has been used as control on the bone repair in the osteoporosis experimental rats model. It was used 30 animals, 5 on the control group- Group 1 (G1) and 25 were ovariectomized bilaterally (OVX). Bone gaps were done 5mm size on the rats calvaria´s and the (OVX) were housed in three different groups concerned by membranes applied or not at the bone gap. Group 2 no membrane applied; Group 3 PTFE membrane and Group 4 P(VDF-TrFE)/BT membrane. Four weeks later, the animals were euthanized and the calvarias were collected to the histological analysis, histomorphometric assays by micro CT and the gene expression by the real time PCR. The histomorphometric analysis showed that the animals which received P(VDF-TrFE)/BT membrane presented similar morphometric parameters better than PTFE. The P(VDF-TrFE)/BT showed a minor expression to RUNX2, BSP, OPN, OSX e RANKL genes; the similar were to RANK e CTSK and the higher expression were to OPG, CALCR e MMP9. These results evidence that the P(VDF-TrFE)/BT could be used as promising biomaterial to bone healing under osteoporosis

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