Isobutylene-rich elastomers bearing functional groups that engage N-arylmaleimides in C-H bond addition and/or alternating copolymerization are described. While inactive to cross-linking when treated at high temperature with peroxide alone, these co-curing elastomers can be cross-linked substantially when combined with bis-maleimide coagents such as N,N’-m-phenylene dimaleimide (BMI). Poly(isobutylene-co-isoprene) (IIR) samples containing relatively high amounts of residual isoprene unsaturation are shown to provide relatively low coagent cure reactivity, whereas IIR derivatives bearing pendant polyether or vinyl ether functionality are shown to provide exceptional cross-linking rates and extents when treated with identical BMI formulations. The design of such co-curing elastomers is discussed, along with the physical properties of the resulting vulcanizates. Isobutylene rich elastomers bearing oligomerizable (C=C) functional groups, macromonomers, that are activated in the presence of free-radical initiators are described. The criteria for determining the macromonomers that are best suited for preparing thermosets of IIR is discussed. While IIR derivatives bearing pendant acrylic, styrenic and maleimide functionality are shown to provide exceptional cross-linking rates and extents, they are also shown to suffer from instability in the absence of peroxide. IIR carrying pendant methacrylic and itaconate functionality are shown to provide a good balance of cure rates and stability. Nitroxyl based radical trap that provides scorch protection to the macromonomers while regenerating the cure extent is discussed. Functional macromonomer derivatives of IIR bearing containing multi-functional pendant groups are discussed. IIR derivatives with itaconate and low amounts of BHT pendant groups is shown to act as bound anti-oxidant while IIR containing pendant fluoro groups are shown to have reduced surface energy. Ionic coagents are used to cross-link IIR containing itaconate pendant groups and their physical properties are discussed. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2012-07-06 11:20:56.915

The human immunodeficiency virus is presently one of the most significant global health issues to date, with a disease burden that encumbers developing and developed nations alike. Although current antiretroviral therapy can help patients maintain undetectable levels of the virus throughout their bodies, once the treatment is ceased, the virus will rebound and disease progression continues. Thus, modalities to; 1- stop HIV transmission and spread, or 2- eradicate the virus once it is acquired are both urgently needed. In this project, we seek to evaluate and understand the impact of a candidate vaccine therapy that targets the HIV protease cleavage sites (PCS) on viral fitness. Vaccination with this modality in a monkey model induces mutations at virus regions that are intolerant to change, presumably affecting the "fitness" of viral strains recovered from vaccines. Preliminary results of the study show that in the vaccine group (n=11), a disruption to one or more of the HIV protease cleavage sites results in improved maintenance of CD4+ T cells compared to unvaccinated controls (n=5). Furthermore, a correlation between the percentage of PCS mutations and reductions in viral load were seen. Our data indicate that the most common sites of mutation occur at two cleavage regions PCS2 and PCS12. We used site directed mutagenesis to introduce multiple PCS mutations into infectious clones of SIV. Our ongoing studies are evaluating the viral fitness of the SIV mutants in a cell lines and PBMC using competitive viral fitness assays. The data from these studies will help inform in the areas of vaccine and therapy development for HIV-1.

Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-04-11T17:28:24Z No. of bitstreams: 1 Dissertacao Gabriela Ricciardiseg.pdf: 2477938 bytes, checksum: 63f6884552d680476da5c151ae960218 (MD5) / Approved for entry into archive by Maria Alice Ribeiro(malice@ufba.br) on 2013-05-02T15:54:56Z (GMT) No. of bitstreams: 1 Dissertacao Gabriela Ricciardiseg.pdf: 2477938 bytes, checksum: 63f6884552d680476da5c151ae960218 (MD5) / Made available in DSpace on 2013-05-02T15:54:56Z (GMT). No. of bitstreams: 1 Dissertacao Gabriela Ricciardiseg.pdf: 2477938 bytes, checksum: 63f6884552d680476da5c151ae960218 (MD5) Previous issue date: 2008 / A cura religiosa é um tema que tem sido bastante abordado pelas CiênciasSociais, principalmente em virtude de relatos de adeptos de diversas religiões e seitas envolvendo a cura. A cura não médica, “espiritual” ou “religiosa”, precisa ser estudada pela ciência a fim de que se possa ter um panorama mais completo sobre as questões envolvendo doença, saúde, aflição e alívio, e como os indivíduos interagem com os seus problemas buscando diversos tipos de tratamento. Este trabalho visa compreender como se dá a experiência de transformação, alívio e cura na União do Vegetal (UDV) numa perspectiva sócio-antropológica. A União do Vegetal é uma das religiões que utiliza um chá enteógeno (cientificamente denominado Ayahuasca) nos rituais religiosos. Fundada na região amazônica em 22 de julho de 1961, por um seringueiro baiano de nome José Gabriel da Costa, o “Mestre Gabriel”, possui uma base doutrinária cristã reencarnacionista e hoje está presente nos centros urbanos do Brasil e exterior. Os adeptos se referem à UDV como sendo uma religião que possibilita transformações positivas nas suas vidas, alívio e cura para os problemas enfrentados. Os problemas vão desde “doenças físicas” ou “da matéria”, a depressão, angústia, dependência de drogas dentre outros. Tendo em vista a importância da narrativa na experiência da aflição e enfermidade, busca-se compreender, através do discurso dos adeptos, como eles concebem tais processos, a que ou a quem atribuem essas transformações, alívio e cura. A finalidade é contribuir com conhecimento científico, expandindo os paradigmas a respeito do fenômeno da “cura religiosa” ou “cura espiritual”. / Salvador

Made available in DSpace on 2013-01-07T15:55:04Z (GMT). No. of bitstreams: 2 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) 12.pdf: 499119 bytes, checksum: e4d2cca1a6b30febd288652f3fe6264f (MD5) Previous issue date: null / Reflete sobre questões relacionadas às crenças que sustentam a manutenção de práticas populares de cura, de como esse saber atravessa gerações sociológicas através da cosmovisão de rezadeiras e receitadores no município de Nova Friburgo, como esse saber se constituiu e como se manteve ao longo do tempo e qual sua influência na formulação do conceito de saúde e doença pelas pessoas em seu cotidiano.

O presente estudo objetivou avaliar a profundidade de polimerização através de testes de microdureza em dois tipos de resina composta com matrizes distintas utilizando um aparelho fotoativador do tipo LED, empregando-se diferentes densidades de energia, sendo avaliados no período inicial (baseline) e após 7 dias. O método utilizado foi o teste de dureza Knoop em amostras de dois compósitos fotoativáveis (P 90, 3M/ESPE, cor A2; Z 250, 3M/ESPE, cor A2). Os corpos-de-prova foram subdivididos em 8 grupos (n=10), metade realizado com cada resina testada. Cada grupo foi definido através de diferentes densidades de energia (600 mW/cm2 x 40s; 1000 mW/cm2 x 40s; 1000 mW/cm2 x 20s; 1400 mW/cm2 x 20s), cada corpo-de- prova obtinha 4 medidas, diferentes profundidades (0, 1, 2 e 3 mm). Cada corpo-de-prova foi confeccionado com o auxilio de uma matriz metálica, constituída por 3 partes, superior, intermediaria e inferior, cada uma com 1 mm de espessura e orifício central com diâmetro de 5 mm. Sobre cada parte preenchida com resina, era colocado um pedaço de tira de poliéster, sobre o qual, com uma lâmina de vidro era exercida uma pressão para promover uma superfície lisa e plana. A unidade fotoativadora utilizada foi LED, para conseguir as diferentes densidades de potência, anéis de plástico foram acoplados na ponta do aparelho fotoativador. A fotoativação foi realizada com a ponta da unidade fotoativadora em contato com a tira de poliéster colocada na parte superior do corpo-de-prova (0 mm). Assim , cada espécime era composto por três partes, cada uma com 1 mm de espessura. Logo após a fotoativação, as partes dos espécimes eram separadas e realizavam-se 5 impressões de dureza Knoop (dureza inicial), com carga de 50g durante 30s, em 4 superfícies, que eram: 1ª) superfície superior da parte superior do espécime, voltada para a fonte de luz (0 mm); 2ª) superfície inferior da parte superior do espécime (1 mm); 3ª) superfície inferior da parte intermediária do espécime (2 mm); e 4ª) superfície inferior da parte inferior do espécime (3 mm). Após 7 dias de estocagem numa estufa a 37ºC, novas leituras de dureza eram realizadas (dureza final). Verificou-se que: 1) A resina composta P 90 obteve menores médias dos valores de dureza Knoop em relação à outra resina composta estudada, Z 250; 2) Quanto maior a profundidade, menores alores de dureza Knoop foram mensurados; 3) Valores de dureza Knoop final foram maiores após 7 dias em comparação a dureza Knoop inicial; 4) De acordo com o aumento da densidade de potência, maiores médias dos valores de dureza Knoop foram mensurados. Esses resultados permitem concluir que: 1) A resina melhora sua propriedade de dureza num período de 7 dias; 2) Quanto maior a profundidade, menor a dureza; 3) quanto maior a densidade de potência utilizada neste trabalho, maior dureza foi avaliado; 4) a resina P 90 obteve valores inferiores a resina Z 250 avaliadas nas mesmas condições. / This study aimed to evaluate the depth of cure through microhardness tests on two types of resin composite with different matrices using LED curing unit, using different energy densities and are assessed during the initial (baseline) and after 7 days. Knoop hardness test was performed in samples made of two light cured composites (P 90, 3M/ESPE, A2; Z 250, 3M/ESPE, A2). The specimens were divided into 8 groups (n=10), and half of them were made with each composite resin tested. Each group was defined by different power densities (600 mW/cm2 x 40s, 1000 mW/cm2 x 40s, 1000 mW/cm2 x 20s; mW/cm2 1400 x 20s), each specimens obtained four measures, different depths (0, 1, 2 and 3 mm). Each specimens was made with the aid of a metal matrix, consisting of 3 parts, superior, intermediate and bottom, each with 1 mm thickness and center hole diameter of 5 mm. On each side filled with resin, was placed a piece of polyester strip, on which, with a glass slide was exerted pressure to promote a flat surface. A unit LED curing was used and to achieve different power densities, plastic rings were attached at the tip of the curing unit. The polymerization was carried out with the tip of the curing unit in contact with the polyester strip placed on top of the specimen (0 mm). Thus, each specimen was composed of three parts, each part with 1 mm thick. Immediately after curing, the parts of the specimens were separated and held up five impressions of Knoop hardness (initial hardness), with a load of 50g for 30s on 4 surfaces, which were: 1) the upper surface of the upper specimen directed to the light source (0 mm), 2) lower surface of the upper specimen (1 mm); 3) lower surface of the middle section of the specimen (2 mm) and 4) lower surface of the bottom of the specimen (3 mm). After 7 days of storage in an oven at 37°C, new hardness re adings were made (final hardness). It was found that: 1) The composite P 90 had lower average values of Knoop hardness in relation to the other studied composite, Z 250, 2) The greater the depth, lower Knoop hardness values were measured, 3) Final values of Knoop hardness were higher after 7 days compared with initial hardness, 4) In accordance with the increase of power density, higher average values of Knoop hardness were measured. These results indicate that: 1) The resin improves the hardness property over a period of 7 days, 2) The greater the depth, the lower the hardness, 3) the higher the power density used in this study, higher hardness was evaluated; 4 ) P 90 resin obtained values less than Z 250 resin, evaluated under the same conditions.

Magister Scientiae Dentium - MSc(Dent) / Resin composite is one of the most commonly used materials in restorative dentistry. However, it has undergone continuous developments like changes in the fillers and initiators. One such improvement is the new bulk-fill composites which are materials intended for bulk placement up to 4mm. However, an optimum polymerization to the full depth of the restoration i.e. complete depth of cure is of utmost importance in order to obtain proper mechanical and physical properties of resin composites. Aim: The aim of this study was to measure the surface hardness of the top and bottom surfaces of the composites and to determine the depth of cure of bulk-fill composites using two different types of light curing units. Material and methods: A total of 160 specimens were used in this study: four bulk-fill composite were used of which two were conventional viscosity bulk-fill composites namely, Tetric N Ceram (Ivoclar Vivadent) and SureFil bulk-fill composite (Densply Caulk) and two were low viscosity flowable bulk-fill composites namely, SDR flowable (Densply Caulk) and Filtek bulk-fill flowable restorative (3M ESPE). Two different curing light were used namely, LED (Elipar Freelight, 3M ESPE) at 1500mW/cm2 and a Quartz Tungsten Halogen (QTH) curing unit (Megalux CS, Megadenta, Germany) at 600 mW/cm2. To evaluate micro-hardness, Vickers hardness at top and bottom of each sample was measured immediately after light curing and after 24 hours post curing using a Zwick micro-hardness machine load 300g/15 seconds. The mean hardness values obtained from the top and the bottom surface of each material were used to compare the micro-hardness of the various materials. The mean values obtained from the bottom surface were compared to the respective values of the top surface of each material (bottom/top ratio) and used to calculate the depth of cure. Results: The micro-hardness test showed a significant difference between the four materials (ANOVA, p<0.05) immediately after curing and after 24 hours post curing. The material with the greatest micro-hardness was SureFil followed by Tetric N Ceram, Filtek bulk-fill flowable and SDR flowable respectively. The material with the greatest depth of cure was Filtek bulk-fill flowable followed by SDR flowable, Tetric N Ceram and SureFil. When the curing lights were compared the Light Emitting Diode Curing Unit (LED) obtained significantly better depth of cure compared to Quartz Tungsten Halogen Light Curing Units. The LED curing light showed greater micro-hardness values than the QTH curing light except for Tetric N Ceram where the QTH curing showed more hardness values than the LED curing light. For all materials, the surface hardness and depth of cure values increased when tested 24hrs after light curing. Conclusion: There was a difference in the micro-hardness values between the four materials where the conventional viscosity materials showed greater surface hardness values than the low viscosity materials but the depth of cure compared to the bulk-fill flowable LED curing lights showed higher hardness values than QTH curing light except for Tetric N Ceram. Depth of cure ratios were found to be lower than 0.80 for all composite types, however the flowable bulk-fill materials showed higher depth of cure than the conventional viscosity bulk-fills. In general LED curing light produced better hardness and depth of cure values than QTH curing light. The low micro-hardness values for the bulk-fill flowable composites and the inadequate polymerization raises a concern regarding placing these materials in bulk. In such cases, the flowable bulk-fills should be protected with a conventional composite "covering or capping" especially in posterior teeth and in deeper cavities. Furthermore, bulk-fill composites should be used in layering incremental technique to ensure sufficient depth of cure.

In survival analysis or time-to-event analysis, one of the primary goals of analysis is to predict the occurrence of an event of interest for subjects within the study. Even though survival analysis methods were originally developed and used in medical re- search, those methods are also commonly used nowadays in other areas as well, such as in predicting the default of a loan and in estimating of the failure of a system. To include covariates in the analysis, the most widely used models are the propor- tional hazard model developed by Cox (1972) and the accelerated failure time model developed by Buckley and James (1979). The proportional hazard (PH) model as- sumes subjects from different groups have their hazard functions proportionally, while the accelerated failure time (AFT) model assumes the effect of covariates is to accel- erate or decelerate the occurrence of event of interest. In some survival analyses, not all subjects in the study will experience the event. Such a group of individuals is referred to `cured' group. To analyze a data set with a cured fraction, Boag (1948) and Berkson and Gage (1952) discussed a mixture cure model. Since then, the cure model and associated inferential methods have been widely stud- ied in the literature. It has also been recognized that subjects in the study are often correlated within clusters or groups; for example, patients in a hospital would have similar conditions and environment. For this reason, Vaupel et al. (1979) proposed a frailty model to model the correlation among subjects within clusters and conse- quently the presence of heterogeneity in the data set. Hougaard (1989), McGilchrist and Aisbett (1991), and Klein (1992) all subsequently developed parametric frailty models. Balakrishnan and Peng (2006) proposed a Generalized Gamma frailty model, which includes many common frailty models, and discussed model fitting and model selection based on it. To combine the key components and distinct features of the mixture cure model and the frailty model, a mixture cure frailty model is discussed here for modelling correlated survival data when not all the subjects under study would experience the occurrence of the event of interest. Longini and Halloran (1996) and Price and Manatunga (2001) developed several parametric survival models and employed the Likelihood Ratio Test (LRT) to perform a model discrimination among cure, frailty and mixture cure frailty models. In this thesis, we first describe the components of a mixture cure frailty model, wherein the flexibility of the frailty distributions and lifetime survival functions are discussed. Both proportional hazard and accelerated failure time models are considered for the distribution of lifetimes of susceptible (or non-cured) individuals. Correlated ran- dom effect is modelled by using a Generalized Gamma frailty term, and an EM-like algorithm is developed for the estimation of model parameters. Some Monte Carlo simulation studies and real-life data sets are used to illustrate the models as well as the associated inferential methods. / Thesis / Doctor of Philosophy (PhD)

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