Torque teno virus (TTV) is a single stranded circular DNA virus and, despite its widespread nature in the human population, its pathogenesis is still unknown. Factors complicating TTV research include its huge genetic diversity, difficulties identifying an uninfected control population, the lack of a small animal model and lack of a good cell culture system for viral propagation. Recently we have identified a TTV homologue (RoTTV) in wild rodents. RoTTV was frequently observed in wood mice and field voles. RoTTV infections were also found in bank voles but not in Mus musculus populations. Analysis of complete genome sequencing shows that several genetic variants are found in wild rodent population with two distinct species containing several diverse genotypes. Furthermore, multiple variants were present in single individuals, consistent with infection patterns seen in humans. RoTTV transcripts in infected wild wood mice have also been detected and fully sequenced. Predicted protein coding regions from these transcripts have been expressed in cell culture and show the different expression patterns. Using cloned genomic DNA it has also been possible to observe the transcription from the virus in vitro and it was shown RoTTV viral titer in the supernatant of culture fluid increased. In addition, RoTTV propagation was observed by using the supernatant of culture fluid. Using cloned genomic DNA and the culture supernatant, an in vivo model system in naïve laboratory wood mice was developed.

The countersteering effect in motorcycles describes the apparent need to steer in the wrong direction in order to cause the chassis of the vehicle to lean over in the required direction just prior to executing a turn. The inherent danger with this procedure is that in a emergency situation where a motorcyclist must execute a sudden swerve to avoid a collision, the required behaviour is counterintuitive and panic may cause the rider to make the wrong initial movement thereby reducing their chance of avoiding a collision. As the importance of the countersteering effect is not taught in UK motorcycle training courses, the current work has attempted to establish whether doing so could significantly improve the ability of riders in swerve to avoid manoeuvres. An initial survey of motorcycle riders suggested some confusion about the nature of countersteering. To explore this further, four groups of riders with different levels of experience and training: novice, experienced, advanced and expert, were tested over a simple swerve to avoid course that was based on the procedure in the current UK motorcycle test. All the riders used the same motorcycle with on-board instrumentation to record the steering effort and the response of the machine. The tests were also videoed to gain extra information about rider behaviour. The results suggest that those riders that had been trained in exploiting countersteering were better able to avoid the obstacle and significantly better at returning the machine to the desired path thereby avoiding a potential secondary collision. It appeared that those riders who had learned by experience were still not proficient when faced with a sudden swerve to avoid scenario.

A proposta deste estudo foi avaliar o comportamento mecânico de dois designs de conexão implante/abutment; hexágono externo e triângulo interno, utilizando parafusos convencionais e parafusos experimentais cone morse. O estudo foi dividido em duas fases: na primeira, foi avaliado o efeito do carregamento mecânico na perda de torque dos parafusos. 40 implantes foram utilizados. Os implantes e abutments foram divididos em 4 grupos: Grupo 1: hexágono externo/parafuso convencional (HE); Grupo 2: triângulo interno/parafuso convencional (TI); Grupo 3: hexágono externo/parafuso cone morse (HECM); Grupo 4: triângulo interno/parafuso cone morse (TICM). Os abutments foram instalados em seus respectivos implantes com torque de aperto de 32Ncm; após intervalo de 10 minutos, foram medidos os valores dos torques de desaperto. Os abutments foram instalados novamente com torque de 32Ncm, e após 10 minutos foram carregados mecanicamente, simulando 1 ano de função oral normal; após o carregamento, os torques de desaperto dos parafusos foram medidos novamente. Os dados foram analisados com o teste one-way ANOVA, com nível de significância de p≤0,05%. Análises por microscopia óptica foram realizadas antes e após os ensaios. Na segunda fase, foi avaliada a resistência à flexão dos conjuntos implante/abutment. Os mesmos 40 conjuntos foram utilizados. Os testes foram realizados em máquina universal de ensaios, com célula de carga de 500 kgf, deslocamento de 1mm/min, e inclinação de 45°. A força máxima de flexão (FMF) e a força de ruptura (FR) foram determinadas. As informações coletadas foram analisadas com o teste one-way ANOVA, para p≤0,05. Análises por microscopia óptica foram realizadas para estudo dos componentes após os ensaios de resistência flexural. Os resultados sugeriram que houve diferença significante (p=0,000) na pré-carga residual antes e após carregamento mecânico entre os dois tipos de parafuso: os parafusos cone morse apresentaram torques de desaperto significativamente superiores aos apresentados pelos parafusos planos convencionais. Houve diferença significante nos resultados da FMF obtidos pelos parafusos planos convencionais e pelos parafusos cone morse (p=0,011), sendo que os conjuntos implante/abutment com parafusos cone morse apresentaram maior resistência à flexão. Para os resultados da FR houve influência significante do tipo de conexão (p=0,019), com melhores resultados para a conexão triângulo interno. Considerando as limitações deste estudo, concluiu-se que os parafusos cone morse apresentaram maiores torques de desaperto em comparação aos parafusos planos convencionais; que o design da conexão protética não teve influência significante sobre o torque de desaperto dos parafusos; que os parafusos cone morse obtiveram maiores valores de resistência à flexão, e que a conexão em triângulo interno obteve maiores valores para a força de ruptura. / The purpose of this study was to evaluate the mechanical behavior of two implant/abutment connection designs; external hex and internal tri-channel, using conventional screws and experimental conical screws. The study was divided in two parts; the first evaluated the effect of mechanical loading in the torque loss of the screws. 40 implants were used. The implants and abutments were divided in 4 groups: Group 1: external hex/conventional screw (HE); Group 2: tri-channel/conventional screw (TI); Group 3: external hex/conical screw (HECM); Group 4: tri-channel/conical screw (TICM). The abutments were installed in their respective implants with a tightening torque of 32Ncm, after a 10 minute interval, loosening torque were measured. The abutments were installed again with a 32Ncm torque, and after 10 minutes, they were mechanically loaded, simulating 1 year of normal oral function; after loading, loosening torques of the screws were measured again. Data were analyzed with one-way ANOVA test, with significance level of p≤0,05. Optical microscopy analysis were performed before and after the tests. The second part evaluated the flexural resistance of the implant/abutment assemblies. The same 40 assemblies were used. The tests were performed in an universal testing machine, with a 500kgf load cell, 1mm/min displacement, and 45° angulation. Maximum bending moment (FMF) and rupture force (FR) were determined. Collected information were analyzed with one-way ANOVA test, for p≤0,05. Optical microscopy analysis were performed for study of the components after the flexural resistance tests. The results suggested that there were significant differences (p=0,000) in the residual preload before and after mechanical loading between the two types of screws: conical screws showed significantly higher loosening torques than conventional flat screws. There were significant differences in the FMF obtained by the conventional flat screws and by the conical screws (p=0,000); the implant/abutment assemblies with conical screws presented higher flexural resistance. For the FR results, there was significant influence of the type of connection (p=0,019); the tri-channel connection presented better results. Considering the limitations of this study, it was concluded that the conical screws presented higher loosening torques compared to conventional flat screws; the design of the implant/abutment connection presented no significant influence on the loosening torques of the screws; conical screws showed higher bending moment values; and the tri-channel connection obtained higher rupture force values.

A proposta deste estudo foi avaliar o comportamento mecânico de dois designs de conexão implante/abutment; hexágono externo e triângulo interno, utilizando parafusos convencionais e parafusos experimentais cone morse. O estudo foi dividido em duas fases: na primeira, foi avaliado o efeito do carregamento mecânico na perda de torque dos parafusos. 40 implantes foram utilizados. Os implantes e abutments foram divididos em 4 grupos: Grupo 1: hexágono externo/parafuso convencional (HE); Grupo 2: triângulo interno/parafuso convencional (TI); Grupo 3: hexágono externo/parafuso cone morse (HECM); Grupo 4: triângulo interno/parafuso cone morse (TICM). Os abutments foram instalados em seus respectivos implantes com torque de aperto de 32Ncm; após intervalo de 10 minutos, foram medidos os valores dos torques de desaperto. Os abutments foram instalados novamente com torque de 32Ncm, e após 10 minutos foram carregados mecanicamente, simulando 1 ano de função oral normal; após o carregamento, os torques de desaperto dos parafusos foram medidos novamente. Os dados foram analisados com o teste one-way ANOVA, com nível de significância de p≤0,05%. Análises por microscopia óptica foram realizadas antes e após os ensaios. Na segunda fase, foi avaliada a resistência à flexão dos conjuntos implante/abutment. Os mesmos 40 conjuntos foram utilizados. Os testes foram realizados em máquina universal de ensaios, com célula de carga de 500 kgf, deslocamento de 1mm/min, e inclinação de 45°. A força máxima de flexão (FMF) e a força de ruptura (FR) foram determinadas. As informações coletadas foram analisadas com o teste one-way ANOVA, para p≤0,05. Análises por microscopia óptica foram realizadas para estudo dos componentes após os ensaios de resistência flexural. Os resultados sugeriram que houve diferença significante (p=0,000) na pré-carga residual antes e após carregamento mecânico entre os dois tipos de parafuso: os parafusos cone morse apresentaram torques de desaperto significativamente superiores aos apresentados pelos parafusos planos convencionais. Houve diferença significante nos resultados da FMF obtidos pelos parafusos planos convencionais e pelos parafusos cone morse (p=0,011), sendo que os conjuntos implante/abutment com parafusos cone morse apresentaram maior resistência à flexão. Para os resultados da FR houve influência significante do tipo de conexão (p=0,019), com melhores resultados para a conexão triângulo interno. Considerando as limitações deste estudo, concluiu-se que os parafusos cone morse apresentaram maiores torques de desaperto em comparação aos parafusos planos convencionais; que o design da conexão protética não teve influência significante sobre o torque de desaperto dos parafusos; que os parafusos cone morse obtiveram maiores valores de resistência à flexão, e que a conexão em triângulo interno obteve maiores valores para a força de ruptura. / The purpose of this study was to evaluate the mechanical behavior of two implant/abutment connection designs; external hex and internal tri-channel, using conventional screws and experimental conical screws. The study was divided in two parts; the first evaluated the effect of mechanical loading in the torque loss of the screws. 40 implants were used. The implants and abutments were divided in 4 groups: Group 1: external hex/conventional screw (HE); Group 2: tri-channel/conventional screw (TI); Group 3: external hex/conical screw (HECM); Group 4: tri-channel/conical screw (TICM). The abutments were installed in their respective implants with a tightening torque of 32Ncm, after a 10 minute interval, loosening torque were measured. The abutments were installed again with a 32Ncm torque, and after 10 minutes, they were mechanically loaded, simulating 1 year of normal oral function; after loading, loosening torques of the screws were measured again. Data were analyzed with one-way ANOVA test, with significance level of p≤0,05. Optical microscopy analysis were performed before and after the tests. The second part evaluated the flexural resistance of the implant/abutment assemblies. The same 40 assemblies were used. The tests were performed in an universal testing machine, with a 500kgf load cell, 1mm/min displacement, and 45° angulation. Maximum bending moment (FMF) and rupture force (FR) were determined. Collected information were analyzed with one-way ANOVA test, for p≤0,05. Optical microscopy analysis were performed for study of the components after the flexural resistance tests. The results suggested that there were significant differences (p=0,000) in the residual preload before and after mechanical loading between the two types of screws: conical screws showed significantly higher loosening torques than conventional flat screws. There were significant differences in the FMF obtained by the conventional flat screws and by the conical screws (p=0,000); the implant/abutment assemblies with conical screws presented higher flexural resistance. For the FR results, there was significant influence of the type of connection (p=0,019); the tri-channel connection presented better results. Considering the limitations of this study, it was concluded that the conical screws presented higher loosening torques compared to conventional flat screws; the design of the implant/abutment connection presented no significant influence on the loosening torques of the screws; conical screws showed higher bending moment values; and the tri-channel connection obtained higher rupture force values.

Orientador: Gustavo Ventorim / Banca: Cristian Inácio de Campos / Banca: Fábio Minoru Yamaji / Resumo: O presente estudo tem por objetivo elucidar sobre a correlação entre a viscosidade e as propriedades mecânicas da polpa. O material utilizado foi uma amostra de Eucalyptus grandis x Eucalyptus urophylla. Os cavacos foram submetidos a cozimentos com tempos de polpação de 90 e 120 minutos. Para as polpas produzidas com tempo de 90 minutos, realizou-se a deslignificação com oxigênio com temperatura de 95°C e para as polpas produzidas com o tempo de 120 minutos, a temperatura do estágio de deslignificação com oxigênio foi de 115°C, objetivando uma maior diferença de viscosidade entre as amostras. Ambas as polpas foram branqueadas a partir das sequências ECF OD(E+P)DD, OAHTD(E+P)DP e OD(E+P)(PO). Posteriormente as polpas foram refinadas em moinho PFI e avaliadas quanto ao índice de rasgo, tração e arrebentamento, segundo as normas da TAPPI (Technical Association of the Pulp and Paper Industry). Os resultados indicam que o aumento do tempo de cozimento em 30 minutos e aumento da temperatura da deslignificação com oxigênio de 95°C para 115°C afetam significativamente a viscosidade da polpa. O refino foi afetado pela diminuição da viscosidade das sequências produzidas com deslignificação com oxigênio à temperatura de 115°C. O índice de rasgo apresentou decréscimo quanto menor a viscosidade da polpa em todas as sequências de branqueamento deste estudo. Os índices de tração e arrebentamento apresentaram decréscimo de acordo com a diminuição da viscosidade em uma mesma sequência, entret... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study aims to elucidate the correlation between the viscosity and the mechanical properties of the pulp. The material used was a sample of Eucalyptus grandisx Eucalyptus urophylla. The chips were cooked with cooking times of 90 and 120 minutes. For the pulps produced in 90 minutes, the delignification with oxygen at temperature of 95ºC was performed and for the pulps produced in 120 minutes, the temperature of the oxygen delignification stage was 115ºC, aiming a greater difference of viscosity between the samples. Both pulps were bleached from the sequences ECF OD(E+P)DD, OD(E+P)(PO) and OAHTD(E+P)DP. Later, the pulps were refined in PFI mill and assessed for the tear, tensile and burst indexes, according to the TAPPI (Technical Association of the Pulp and Paper Industry) standards. The results indicate that the increase of cooking time in 30 minutes and the increase of temperature in oxygen delignification from 95°C to 115°C affect significantly the pulp viscosity. The refining was affected by the viscosity reduction of the sequences produced with delignification with oxygen at temperature of 115ºC. Tear index decreased as the pulp viscosity was lower, in all the bleaching sequences. Tensile and burst indexes presented decrease with the decrease of the viscosity in the same sequence, however, when comparing different bleaching sequences, there was no relation between the tensile and burst indexes with the pulp viscosity / Mestre

Orientador: Araildo Lima da Silva / Banca: Tamotsu Hirata / Banca: Luis Alberto Batista / Resumo: Os conseqüentes avanços na medicina esportiva incluem a busca por novos métodos tecnológicos que viabilizam uma melhor e mais eficaz avaliação muscular e articular no corpo humano. Associados a isso, a grande ocorrência de lesões de membros inferiores em especial aquelas da articulação do joelho, faz com que a procura por novos métodos de avaliação seja incentivada. Um recurso valioso consiste num método auxiliar de avaliação das lesões esportivas onde o exame deverá ser realizado através da aplicação de uma resistência constante. Na prática esportiva, há por um lado a importância da proporção do equilíbrio muscular agonista/antagonista, ou seja, do equilíbrio flexor/extensor representado, respectivamente, pelos isquiotibiais/quadríceps da coxa. De outro, a comparação dos valores absolutos da função muscular dos membros inferiores, quer seja para o quadríceps, ou para os isquiotibiais. Resultados alterados podem estar relacionados às lesões esportivas ou suas seqüelas. De interesse para o atleta e para a equipe multidisciplinar é poder dispor de um método de avaliação funcional muscular objetivo e seguro, que forneça dados confiáveis e reprodutíveis. Neste contexto um estudo foi desenvolvido objetivando-se a avaliação dos valores de torque bidirecional (flexão-extensão), potência, tempo e trabalho muscular do joelho quando submetido a uma resistência constante. Para tanto um dispositivo capaz de avaliar esses parâmetros foi desenvolvido no laboratório de biomecânica do Departamento de Mecânica da Unesp de Guaratinguetá, para gerar dados que caracterizem o estado físico e o desempenho dos indivíduos avaliados. Foram utilizados no estudo 19 voluntários do sexo masculino com idade entre 20-30 anos sem histórico de lesão na articulação do joelho, que foram submetidos a exercícios de flexão e extensão com amplitude de movimentos de 90 a 180° durante 40 segundos. / Abstract: The consequent advances in sports medicine include the search for new technological methods that permit a more efficient evaluation of the musculature and joints of the human body. The search for new methods of evaluation has been stimulated by the increased occurrence of injuries to inferior members and in particular knee articulation. A valuable approach consists of an auxiliary method of evaluation of sportive injuries. This examination is carried out through the application of a constant resistance. In sports practice, the agonist / antagonist muscle balance, that is, the flexor/extensor balance represented, respectively, by the hamstring muscle/quadriceps femuris, plays an important role. On the other hand, the comparison between the absolute values of the inferior members is also relevant. Changed results usually relate to sports lesions or their sequels. The development of an objective and safe method to evaluate muscular functionality will provide for reliable and reproducible results of the utmost importance to athletes and multidisciplinary teams. Therefore, a study was carried out proposing to evaluate values of bi-directional torque (flexion-extension), power, time and muscular effort of the knee when submitted to a constant resistance. To accomplish this, a device capable of evaluating these parameters was developed in the biomechanics laboratory of the Department of Mechanics at UNESP - Guaratinguetá. This device generated data that characterized the physical state and performance of the evaluated individuals. The apparatus was used in the study of 19 male volunteers, 20 - 30 years old without pathological history of joint injuries. These volunteers performed flexion and extension exercises during 40 seconds, with an amplitude of movements from 90 to 180°. From these results, a minimum performance standard was determined that characterized good performance among individuals evaluated by the system. / Mestre

Orientador: Lafayette Nogueira Júnior / Banca: Tarcísio José Arruda de Paes Junior / Banca: Argemiro Soares da Silva Sobrinho / Resumo: Esta pesquisa se propôs verificar a manutenção do torque, após fadiga mecânica, de parafusos de pilares protéticos com recobrimento de carbono tipo diamante (DLC) e com dopagem de diamantes (CD-DLC) submetidos ao retorque, em conexões hexagonais externa (HE) e interna (HI). Implantes HE e HI e diferentes tratamentos do parafuso protético foram alocados em grupos experimentais (n = 5): sem tratamento e não submetidos a fadiga (HE-CON) (HI-CON); sem tratamento fadigados (HECONF) (HI-CONF); com DLC fadigado (HE-DLCF) (HI-DLCF) e com CDDLC fadigados (HE-CD-DLCF) (HI-CD-DLCF). Os recobrimentos de DLC e CD-DLC foram depositados a plasma pelo método PECVD. As amostras (implante + parafusos + coroa metálica), que já haviam sido expostas a 1 milhão de ciclos de fadiga, foram retorqueadas com torquímetro digital, com o torque recomendado pelo fabricante 30 N (HE) e 20 N (HI), e submetidos novamente a 1 milhão de ciclos mecânicos. Ao término da fadiga, os parafusos foram destorqueados para verificar a manutenção do torque. Parafusos de cada grupo experimental foram selecionados para observação em MEV. A análise estatística foi realizada pelo teste Anova 2- Fatores (α = 0,05). Não houve interação entre os fatores em estudo (p = 0,765); o tratamento dos parafusos (p = 0,638) e o tipo de conexão (p = 0,615) não apresentaram diferença estatística. Alterações como danos nas roscas do parafuso e remoção do filme foram observados entre os grupos experimentais. Os grupos com revestimento apresentaram pouco ou nenhum dano nas roscas dos parafusos. O revestimento de DLC e CDDLC parece não ter interferido na adaptação do parafuso ao implante. Parafusos protéticos recobertos com DLC e CD-DLC, após o retorque, não elevaram a manutenção do torque / Abstract: The study analyzed the torque maintain of the screw abutments, with coating of diamond-like carbon (DLC) and doping of diamond (CD-DLC), submitted the retorque in external hexagonal (EH) and internal (IH) connections; after mechanical fatigue. HE and HI implants and different treatments of the abutments screws were divided into experimental groups (n = 5): untreated and not subjected to fatigue (EH-CON) (IHICON); fatigued untreatment (EH-CONF) (IH-CONF); fatigued with DLC (EH- DLCF) (IH-DLCF) and fatigued with CD-DLC (EH-CD-DLCF) (IH-CD-DLCF). The DLC and CD-DLC coating was deposited by plasma, PECVD method. Samples (Implant + abutment screew + metal crown), which had been exposed to 1 million fatigue cycles were retorquiadas, digital torque wrench, to the torque recommended by the manufacturer 30 N (HE) and 20 N (HI), and submitted again to 1 million cycles mechanics. At the end of fatigue, the screws were destorquiados to check the maintenance of torque. Screws from each experimental group were selected for observation by SEM. Statistical analysis was performed by ANOVA 2 Factors test (α = 0.05). There was no interaction among the factors studied (p = 0.765); the treatment of screws (p = 0.638) and the connection type (p = 0.615) showed no statistical difference. The microscopy images showed damage the threads and covering the presence of HI connections. Changes such as damage on the screws threads and film removal were observed among the experimental groups. The coating groups showed little or no damage on the screws threads. The DLC and CD-DLC coating did not interfere in the screw adaptation on the implant. Abutments screew coating with DLC and CD-DLC, after retorque, no raised torque maintenance / Mestre

Orientador: Lafayette Nogueira Júnior / Co-orientador: Marcos Massi / Banca: Tarcisio José de Arruda Paes Junior / Banca: Luís Guilherme Scavone de Macedo / Resumo: Objetivo: Avaliar os valores de torque reverso RT(%) de parafusos protéticos de liga de titânio recobertos com um filme de carbono amorfo tipo diamante (DLC) e filme dopado com partículas de diamante(CD-DLC) comparando-os com parafusos sem tratamento (controle). Método: Foram utilizados 60 implantes de plataforma regular, divididos de acordo com o tipo de conexão (hexágono externo e hexágono interno) e o tratamento do parafuso protético (n=10): Grupo A1: hexágono externo/parafuso controle; Grupo A2: hexágono externo/parafuso com DLC; Grupo A3: hexágono externo/parafuso com CD-DLC; Grupo B1: hexágono interno/parafuso controle; Grupo B2: hexágono interno/parafuso com DLC; Grupo B3: hexágono interno/parafuso com CD-DLC. Os filmes de DLC e CD-DLC foram depositados pelo processo conhecido como PECVD (Plasma Enhanced Chemical Vapour Deposition). Os implantes foram inseridos em blocos de poliuretano e as coroas protéticas cimentadas sobre os pilares que foram parafusados aos implantes. O torque reverso foi mensurado após ciclagem mecânica (1.106 ciclos). A análise estatística foi realizada pelo teste Anova 1 fator e Teste de Tukey e Teste t-student com nível de significância de 5%. Resultados: A análise dos resultados mostraram que após a ciclagem mecânica o torque reverso RT(%) do grupo sem tratamento (A1) foi significativamente maior que a dos grupos DLC (A2) e CD-DLC (A3) (p=0,0001), para os parafusos das conexões HE. Entretanto não houve diferença estatística entre os grupos com e sem tratamento na manutenção do torque para os parafusos dos grupos de conexão HI (p= 0.5476). Conclusão: Nas condições estudadas, concluiu-se que os parafusos revestidos com filmes DLC não foram efetivos na manutenção do torque reverso em relação aos parafusos sem tratamento para ambas... / Abstract: Objective: To evaluate the values of reverse torque RT ( % ) of prosthetic screws titanium alloy coated with a film of diamond-like carbon (DLC) and DLC film doped with diamond particles (CD- DLC) comparing them with screws without treatment (control). Method: Sixty implants were divided into six groups according to the type of connection (external or internal hex) and type of abutment screw (n = 10 ): Group A1: external hexagon / screw control, Group A2: external hexagon / screw with DLC; group A3: external hexagon / screw with CD- DLC; group B1: internal hex / screw control; group B2: internal hex / screw with DLC; group B3: internal hex / screw with CD- DLC. The DLC films and CD - DLC were deposited by PECVD process (Plasma Enhanced Chemical Vapour Deposition). The implants were inserted into polyurethane resin, and crowns of nickel chrome cast were cimented and the abutments screwed into the implants. The reverse torque was measured after the mechanical cycling (1.106 cycles). Statistical analysis was performed by one factor ANOVA and Tukey's test, with significance level of 5%. Analysis was performed screws through scanning electron microscopy (SEM) before and after loading . Results: The results showed that after mechanical reverse torque RT (%) for the untreated group (A1) was significantly higher than the one of the DLC groups (A2) and CD -DLC (A3) (p = 0.0001). However, there was no statistical difference for the groups with and without coating in maintaining torque for the screws' internal hex connections (p = 0.5476). Conclusion: After mechanical cycling, the diamond-like carbon with and without doping of diamond on the screws for abutments, showed no improvement in maintaining the torque in external and internal hex connections... (Complete abstract click electronic access below) / Mestre

The motion of domain walls due to the spin torque generated by coherent carrier transport is of considerable interest for the development of spintronic devices. We model the charge and spin transport through domain walls in ferromagnetic semiconductors for various systems. With an appropriate model Hamiltonian for the spin– dependent potential, we calculate wavefunctions inside the domain walls which are then used to calculate transmission and reflection coefficients, which are then in turn used to calculate current and spin torque. Starting with a simple approximation for the change in magnetization inside the domain wall, and ending with a sophisticated transfer matrix method, we model the common π wall, the less–studied 2π wall, and a system of two π walls separated by a variable distance. We uncover an interesting width dependence on the transport properties of the domain wall. 2π walls in particular, have definitive maximums in resistance and spin torque for certain domain wall widths that can be seen as a function of the spin mistracking in the system — when the spins are either passing straight through the domain wall (narrow walls) or adiabatically following the magnetization (wide walls), the resistance is low as transmission is high. In the intermediate region, there is room for the spins to rotate their magnetization, but not necessarily all the way through a 360 degree rotation, leading to reflection and resistance. We also calculate that there are widths for which the total velocity of a 2π wall is greater than that of a same–sized π wall. In the double–wall system, we model how the system reacts to changes in the separation of the domain walls. When the domain walls are far apart, they act as a spin–selective resonant double barrier, with sharp resonance peaks in the transmission profile. Brought closer and closer together, the number and sharpness of the peaks decrease, the spectrum smooths out, and the domain walls brought together have a transmission spectrum with many of the similar features from the 2π wall. Looking at the individual walls, we find an interesting interaction that has three distinct regimes: 1) repulsion, where the left wall moves to the left and the right wall to the right; 2) motion together, where the two walls both move to the right, even at the same velocity for one special value of separation; and 3) attraction, where the left wall moves to the right and the right wall moves to the left. This speaks to a kind of natural equilibrium distance between the domain walls. This is of major interest for device purposes as it means that stacks of domain walls could be self–correcting in their motions along a track. Much experimental work needs to be done to make this a reality, however.

This thesis investigates the development of a machine which is termed as singly salient reluctance (SSR) motor and its drive system. The stator of SSR motor is identical to that of a conventional induction motor or any other ac machine. Its rotor has salient poles with internal flux barriers or flux guides. This research covers the detailed designs of the SSR motors and their magnetic circuit analysis using finite element method (FEM). The parameters which are important for designing the SSR motor are investigated. This investigation resulted in designs which have low manufacturing cost as well as high torque per ampere, efficiency and power factors. This thesis also researches the different drive system for the SSR motor. The SSR motor is tested as a variable speed drive with closed loop control and supplied with dc source. Therefore for this purpose a controller system is designed and built. In addition, the SSR motor supplied by ac source using open loop control is also tested for synchronous operation. Some of the proposed designs are built and their performance compared with their predicted analysis. The SSR motors showed a competitive performance compared with equivalent induction motor in both efficiency and power factor. However the validity of the theoretical designs is assessed by comparing them with experimental results. Quite good agreement between experimental and theoretical evaluations has been achieved. In addition, suggested further improvements for SSR motors and drive systems are discussed. / Doctor of Philosophy (PhD)