Self-ligating brackets, including molar buccal tubes, have gained popularity in recent decades. The primary advantage of using self-ligating systems has been based on the claim that they provide reduced friction and therefore reduced sliding resistance of the arch wire contained within their respective slots.1 This form of reduced friction and sliding resistance has been proposed to require less force and therefore produce more physiologic tooth movements.7-9 Limited scientific evidence is currently available to establish quality control of these products. The purpose of this study is to use Micro Computed Tomography (MicroCT) to analyze self-ligating molar tubes manufactured by different companies. Methods used here provide a novel way for measuring the accuracy and quality of these materials. This study has provided a highly innovative approach that had not been previously accomplished. Forty self-ligating lower left first mandibular molar samples were obtained from four different companies. Five samples from each company were randomly selected and scanned using MicroCT to determine the internal slot lumen of each tube for analysis of precision volumetric measurements. Additionally, qualitative analysis of the lumen of each tube was investigated for the presence of any internal slot defects or imperfections. Results showed that the volumetric slot measurements of all samples were highly statistically significant (P<0.001) and were found to be oversized compared to what is claimed by their respective companies. Qualitative analysis of all samples illustrated varying defects contained within their respective internal slot lumens. Notable defects included notched, beveled and irregular corners, as well as the presence of some bulbous metal projections. Based upon the results obtained in this study, it was determined that the investigated self-ligating buccal tubes, produced by all the companies tested, were oversized and had various internal slot defects. The potential clinical significance of these dimensional inaccuracies may include an increased amount of friction and a lack of torque control during tooth movement. / Oral Biology

Currently, the design model for flexural rupture of an eccentrically loaded bracket plate is based on the material tensile rupture strength times the net elastic section modulus. Different bolt and plate sizes were tested to determine if this model is correct. It was found that the current model is conservative and that the material tensile rupture strength times the net plastic section modulus is a superior design model. Also, limited finite element modeling was performed to predict the elastic stiffness of such connections. The resulting data correlates well with test results, and confirms that most of the connection ductility comes from bolt plowing. These results can be used for splice plate connections in cantilever construction, as well. / Master of Science

The effect on shear bond strength of bracket movement after seating the brackets and before light curing has not been reported. The purpose of this study was to determine the effect of linear and rotational pre-cure bracket movement on the shear bond strength of orthodontic brackets. 100 extracted human maxillary premolars were divided into 5 groups of 20 teeth each. The control group was bonded with no pre-cure bracket movement, and test groups were bonded with pre-cure bracket movement of 2 mm, 4 mm, 45¢ª or 180¢ª. Debonding force was measured with an Instron universal testing machine. Results were analyzed by ANOVA. Weibull survival analysis was used to determine the force required to produce a 5% bracket failure rate. Differences in the Adhesive Remnant Index (ARI) were analyzed by chi-square. No significant differences between groups were found for the mean shear bond strength or Weibull estimates. ARI scores differed significantly.

This Master's thesis clarifies the significance of Frölicher-Nijenhuis bracket and its applications in problems of physics. The basic apparatus for these applications is differential geometry on manifolds, tensor calculus and differential forms, which are contained in the first part of the thesis. The second part summarizes the basic theory of calculus of variations on manifolds and its selected applications in the field of physics. The last part of the thesis is devoted to the applications of Frölicher-Nijenhuis bracket in the derivation of Maxwell's equations and to the description of the geometry of ordinary differential equations.

O consumo de qualquer parte do organismo de um fungo denomina-se fungivoria e são raros os estudos que abordam a temática da interação trófica entre suas estruturas reprodutivas (basidiomas) e os insetos. Mesmo que seja um hábito alimentar freqüente entre os coleópteros, com muitas famílias obrigatoriamente fungívoras, pouco se conhece sobre a estruturação dessa assembléia. Entretanto, sabese que existem preferências por determinadas espécies de fungos, tanto para a postura dos ovos quanto para o próprio consumo. Algumas questões que este estudo aborda referem-se à riqueza e à especificidade dos besouros fungívoros. Adicionalmente investigarei a influência da taxonomia dos fungos, bem como da consistência e do sistema hifal dos basidiomas para o processo de seleção que as espécies de besouros realizam. Também foi verificado se a posição taxonômica dos besouros está relacionada com o grupo de fungos que estes utilizam ou com a consistência dos seus basidiomas. Foram realizadas oito coletas em um ambiente de Floresta Ombrófila Mista no Estado do Rio Grande do Sul, obtendo-se 376 indivíduos das Ordens Polyporales e Hymenochaetales. Estes espécimes foram mantidos individualizados em laboratório por três meses para a constante retirada dos besouros adultos e então dissecados. Todos os fungos que apresentaram besouros fungívoros associados (N = 207) foram identificados e totalizaram 40 espécies. Os coleópteros totalizaram 447 ocorrências e foram classificados em 90 morfoespécies e 20 famílias, sendo Ciidae e Staphylinidae as mais representadas. Os basidiomas foram classificados quanto às suas classes de consistência seguindo um gradiente de durabilidade e rigidez. A riqueza de besouros variou conforme a espécie do hospedeiro e não foram encontrados fatores que influenciam a variação de riqueza de besouros em fungos. A especificidade dos besouros não apresentou relação com a longevidade dos basidiomas. Também se verificou que a posição taxonômica dos fungos, bem como a consistência dos basidiomas, interferem na escolha do hospedeiro pelos besouros. Além disso, se observou que besouros mais relacionados filogeneticamente não utilizam uma assembléia de fungos mais semelhante nem basidiomas com consistências semelhantes. Isso demonstra que a habilidade em consumir as mesmas espécies não está tão relacionada com a filogenia dos besouros como ocorre com os herbívoros. / Fungivory is the consumption of any part of the fungi organism and just a few studies were done about the trophic interactions of its reproductive structures, so called basidiomes, and insects. Even though this is a disseminated habit among Coleoptera, which has many obligated fungivores families, little is known about its community organization. However, there have been works about feeding preferences and oviposing sites of some fungi species. Some of the questions of this study refer to richness and specificity of fungivores beetles on their host. It was also investigated the influence of fungi taxonomy, basidiomes consistency and hyphal system for the selection process of the beetle species, as well as the importance of the taxonomic position of the beetles regarding the host group they use and the basidiome´s consistency. The basidiomes of Polyporales and Hymenochaetales Orders were collected in an Araucaria angustifolia forest of Rio Grande do Sul State. It was obtained 376 fungal individuals, which were kept in the laboratory, individually separated in containers for three months, while the newly emerged beetles were captured, and the fungi were dissected afterwards. All individuals of fungi that had associations (207) were identified (40 species). It was found 447 occurcences of Coleoptera, which were classified in 90 morphospecies belonging to 20 families, with Ciidae and Staphylinidae being the most abundant. The basidiomes where classified by its consistency, following a longevity and hardness gradient. Beetle richness varied among fungal species and no factors that might influence the richness variation in fungi was found. Its specificity did not seem to be related to the longevity of the basidiomes. It was also verified that the fungus taxonomy as well as the consistency of its basidiomes demonstrated some importance for the process of host selection. Regarding the Coleoptera taxonomy, it was not verified that the more phylogenetic related ones use a more similar group of hosts or basidiomes that have similar consistency. This demonstrates that the ability to feed on the same species is not so related to the phylogeny of fungivore beetles as it occurs with herbivores.

Made available in DSpace on 2017-07-10T14:57:31Z (GMT). No. of bitstreams: 1 paulo_ guilherme.pdf: 1519251 bytes, checksum: 15d6c712ac248d997ddd8dbce7c01880 (MD5) Previous issue date: 2016-03-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The adhesion evolution in dentistry, currently, has suggested the nanoparticles addition to the composites in order to improve their mechanical properties. The aim of this study was to compare direct and indirect bracket bonding and to evaluate possible changes due to carbon nanotubes (CN) addition to two adhesives used in indirect bonding by examining the following variables: shear bond strength (SBS), bond failure location and microleakage in the enamel/composite interface. One hundred and eighty bovine incisors underwent 37% phosphoric acid etching and were randomly divided into 9 groups (n=20): (1) direct bonding with Transbond XT adhesive; (2) indirect bonding with Sondhi adhesive; (3), (4) and (5) indirect bonding with Sondhi to which CN at 0.5%, 0.25% and 0.05% concentrations were included; (6) indirect bonding with Concise adhesive; (7), (8) and (9) indirect bonding with Concise to which CN at 0.5%, 0.25% and 0.05% concentrations were included. Transbond XT resin was used in all groups. Maximum SBS was measured with a mechanical testing machine, the location of bond failure was evaluated using the Adhesive Remnant Index (ARI) and the microleakage was measured utilizing scores. One-way analysis of variance followed by the Tukey test (P<.05) was used to compare the SBS among groups, and the differences in ARI and microleakage scores were evaluated using the Kruskal-Wallis test (P<.05). The SBS in group 1 was statistically higher than groups 2 to 6 (P<.05). ARI analysis did not reveal statistically significant differences among the groups (P>.05). In CN groups, there was no statistical difference (P>.05) in SBS or ARI. About the microleakage in the enamel/composite interface, there was a statistically significant difference in group 1 compared to groups 2 and 6, and in group 4 compared to groups 3 and 5 (P<.05). The direct technique was superior to the indirect technique in SBS and microleakage. CN addition to Concise and Sondhi, at the concentrations used, did not significantly increase SBS, ARI or microleakage. / A evolução na área da adesão em Odontologia tem, atualmente, sugerido o acréscimo de nanopartículas ao material adesivo com o propósito de melhorar as suas propriedades mecânicas. Diversos tipos de partículas de carga podem ser adicionados, e entre eles, estão os nanotubos de carbono. A técnica de colagem indireta de bráquetes ortodônticos, na qual os acessórios são posicionados no modelo de gesso da arcada dentária do paciente e, através de uma moldeira, são transferidos aos dentes, parece ser bastante vantajosa, porém, a adesão ainda gera dúvidas com relação à resistência e ao índice de falhas. O objetivo deste trabalho foi comparar as técnicas direta e indireta de colagem de bráquetes, além de avaliar possíveis alterações causadas pela adição de nanotubos de carbono a dois tipos de sistemas adesivos na colagem indireta de bráquetes com relação às seguintes variáveis: resistência de união por microcisalhamento, quantidade de compósito remanescente sobre o esmalte dentário, através do Índice de Remanescente Adesivo (IRA), e microinfiltração ocorrida sob os bráquetes. Para tanto, foram utilizados 180 incisivos bovinos divididos aleatoriamente nos seguintes grupos: G1 (Transbond Controle): colagem direta com adesivo Transbond XT (3M Unitek - Monrovia - EUA); G2 (Sondhi Controle): colagem indireta com adesivo Sondhi Rapid Set (3M Unitek, Monrovia, USA); G3, G4, G5: colagem indireta utilizando o adesivo Sondhi Rapid Set (3M Unitek, Monrovia, USA), com sua porção base acrescida de nanotubos de carbono nas concentrações, respectivamente de 1%, 0,5% e 0,1%; G6: (Concise Controle): colagem indireta com adesivo Concise (3M Unitek - Monrovia - EUA); G7, G8 e G9: colagem indireta utilizando o adesivo Concise (3M Unitek - Monrovia - EUA), com sua porção base acrescida de nanotubos de carbono nas concentrações, respectivamente de 1%, 0,5% e 0,1%. Para a colagem, em todos os grupos foi utilizada a resina composta 10 Transbond (3M Unitek - Monrovia - EUA). Os dados obtidos foram submetidos à análise estatística específica para cada uma das variáveis. Com relação à resistência ao microcisalhamento, observou-se diferença estatisticamente significante do grupo 1 em relação aos grupos 2 e 6 (p<0,05). No que diz respeito ao IRA, não houve diferença estatisticamente significante entre os grupos (p>0,05). Já com relação à microinfiltração ocorrida sob os bráquetes, houve diferença estatisticamente significante do grupo 1 em relação aos grupos 2 e 6, e do grupo 4 em relação aos grupos 3 e 5 (p<0.05). Com base nos resultados obtidos, concluiu-se que a técnica direta mostrou-se superior em relação à técnica indireta nos quesitos de resistência ao microcisalhamento e microinfiltração. Além disto, a adição de nanotubos de carbono aos sistemas adesivos Concise (3M Unitek - Monrovia - EUA) e Sondhi Rapid Set (3M Unitek, Monrovia, USA), não se mostrou vantajosa, nas concentrações avaliadas, no que diz respeito ao aumento da resistência ao microcisalhamento dos bráquetes, na quantidade de compósito remanescente sobre o esmalte dentário e na prevenção da ocorrência de microinfiltração sob os mesmos.

In this work, Schr&ouml / dinger and Dirac equations will be examined in geometries that confine the particles to hypersurfaces. For this purpose, two methods will be considered. The first method is the thin layer method which relies on explicit use of geometrical relations and the squeezing of a certain coordinate of space (or spacetime). The second is Dirac&rsquo / s quantization procedure involving the modification of canonical quantization making use of the geometrical constraints. For the Dirac equation, only the first method will be considered. Lastly, the results of the two methods will be compared and some notes on the differences between the results will be included.

The recent improvement of additive manufacturing has allowed designers to achieve a level of complexity and customizability that is difficult or impossible to accomplish using traditional manufacturing processes. As a result, much research has been conducted on developing new methods to utilize the larger design space brought by additive manufacturing. One such research area is in the design of mesoscale lattice structures. Mesoscale lattice structures are a type of cellular structure with support element sizes on the order of magnitude of centimeters. These types of structures are engineered for high performance and have applications in industries where both low weight and high strength are desired. However, due to the small size of their struts, these structures can easily have hundreds to thousands of individual struts. As a result, design poses a unique challenge. Current methods approach design of mesoscale lattice structures as a topological optimization problem, treating each strut diameter in the structure as a design variable. For structures with a fewer number struts, these optimization methods can converge, but will generally be very time-consuming. For structures with a large number of struts, the optimization problem becomes too large for current algorithms to solve. In previous research, a new, highly efficient design method for mesoscale lattice structures was presented that eliminates the need for global size or topological optimization. This method, termed the Size, Matching and Scaling method, used a unique combination of a solid-body finite element analysis and a library of pre-defined lattice configurations, termed the "unit-cell library," to generate lattice topologies. The results from this method were highly promising: design time was significantly reduced when compared to optimization methods. Furthermore, lattices designed using the SMS method had performance results that were either comparable or better than their optimized counterparts. However, the method developed was highly conceptual, lacking a true systematic methodology for generating topologies and suffering from some gaps in implementation. In this research, we present a modified Size Matching and Scaling (SMS) design method. Firstly, we introduce and outline the modified methodology. This methodology particularly includes an optimization step for determining strut diameters that replaces the manual search used in the original method. Secondly, we expand and explore the unit-cell library in an attempt to improve the performance of lattices generated using the SMS method. In particular, we optimize several unit-cell configurations and compare their performance in the context of the SMS method. Finally, we test the updated SMS methodology and unit-cell library using various design examples. Results from the various example problems indicate that optimization is not only a viable systematic method for determining diameter values, but is actually preferred to the manual, iterative process used in the original method. Furthermore, various optimization algorithms and approaches yield different results. Between the two optimization algorithms utilized in this method: constrained optimization and least-squares minimization, constrained minimization converges faster, but least-squares minimization yields slightly improved performance results. In addition to these algorithms, a one-variable approach using an untested, simplifying assumption, dubbed the "28% approach," was tested. Results indicate that this assumption was incorrect and cannot be utilized. Finally, results from the expanded unit-cell library indicate that the best unit-cell configuration is still the same original unit-cell configuration utilized in the first SMS method. The addition of more unit-cell does not improve the performance of structures generated using the SMS method. In fact, both performance and design time worsen when additional configurations are utilized.

This degree project is the final part of the bachelor in mechanical engineering at Linnaeus University in Växjö. The project has been accomplished at ALT Hiss AB in Alvesta. The company manufactures hydraulic elevators, less traction elevators and escalators. The purpose of this thesis has been to design a tool that plumbs the elevator shaft. The thesis has been completed with literature studies, interviews and data collections. The final concept sketch and idea drawing is presenting the result.

Made available in DSpace on 2014-06-11T19:27:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-05Bitstream added on 2014-06-13T18:30:59Z : No. of bitstreams: 1 guimaraes_acm_me_guara.pdf: 1463910 bytes, checksum: 86d009497e85e3bccfe639908d568618 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Braquetes ortodônticos são feitos de diversos tipos de materiais, tais como, metais, cerâmicas e polímeros. Entre todos os materiais metálicos, o aço inoxidável é o mais empregado devido ao seu baixo custo associado a sua resistência à corrosão. No ambiente oral, eles estão sujeitos a fluídos agressivos e variações de pH, levando a liberação de íons nos tecidos e fluídos. Modificações na superfície destas ligas foram realizados utilizando tratamentos mecânicos, eletroquímicos, químicos e físicos. O carbono amorfo hidrogenado (a-C: H) preparado para técnicas de deposição apresentam muitas propriedades atraentes como alta dureza, serem químicamente inertes e biocompatíveis. Neste estudo in vitro, filmes de a-C:H foram depositados em braquetes ortodônticos pela técnica de deposição química por plasma de radiofreqüência (PECVD) e inibiu a liberação de íons níquel. Após o tratamento de superfície, os braquetes foram colados em incisivos bovinos com uma resina composta e as amostras foram imersas em soro fisiológico por 30 dias à 37 º C. Durante o tempo de imersão as amostras foram lavadas e imersas em flúor diariamente. Antes da imersão, o arranjo estrutural dos filmes foi analisado por espectroscopia de Raman e medidas do ângulo de contato foram realizadas, a fim de avaliar a molhabilidade da superfície. Espectrometria de absorção atômica foi usada para medir a liberação de elementos a partir de amostras e a análise superficial foi realizada em microscópio eletrônico de varredura (MEV). Os resultados mostraram que o revestimento previne a liberação de Ni dos braquetes nos testes estatísticos e o níquel foi liberado de outros grupos sem tratamento de superfície . A análise de variância não indicou diferença significativa entre os grupos depois do ensaio de cisalhamento. / Orthodontics brackets have been made from a variety of materials such as metals, ceramics and polymers. Among all the metallic materials, stainless steel are the most popular due low cost associated with reasonable corrosion resistance. In oral environment, they are subject aggressive fluids and pH variation can be leave nickel ions release to body tissues and fluids. Surface modifications of these alloys have been realized using mechanical, electrochemical, chemical and physical treatments. Hydrogenated amorphous carbon (a-C:H) prepared by deposition techniques have very attractive properties such as high hardness, chemical inertness and biocompatibility. In this in vitro study, a-C:H films were deposited on orthodontics brackets by r.f. plasmaenhanced chemical vapour deposition (PECVD) from inhibited nickel ions release. After treatment, brackets were bonded to bovine incisors with a composite resin and samples were immersed in physiological serum for 30 days at 37 ºC. During immersion time samples were brushed and/or immersed in mouthwashes daily. Prior immersion, the structural arrangement of films was probed by Raman spectroscopy and contact angle measurements were carried out in order to evaluate the wettability of surface. Atomic absorption spectrophotometry was used to measure the release of elements from the samples and SEM for surface analysis. Results showed that the coating prevents Ni release of brackets for statistic test and nickel was released for others groups. Analysis of variance no indicated significance different among groups after shear testing.