Monodispersed nanoparticles of poly-N-isopropylacrylamide-co-allylamine (PNIPAM-co-allylamine) and PNIPAM-co-acrylic acid (AA) have been synthesized and used as building blocks for creating three-dimensional networks. The close-packed PNIPAM-co-allylamine and PNIPAM-co-AA nanoparticles were stabilized by covalently bonding neighboring particles at room temperature and at neutral pH; factors which make these networks amicable for drug loading and release. Controlled release studies have been performed on the networks using dextran markers of various molecular weights as model macromolecular drugs. Drug release was quantified under various physical conditions including a range of temperature and molecular weight. These nanoparticle networks have several advantages over the conventional bulk gels for controlling the release of biomolecules with large molecular weights. Monodispersed nanoparticles of poly-N-isopropylacrylamide-co-allylamine (PNIPAM-co-allylamine) can self-assemble into crystals with a lattice spacing on the order of the wavelength of visible light. By initiating the crystallization process near the colloidal crystal melting temperature, while subsequently bonding the PNIPAM-co-allylamine particles below the glass transition temperature, a nanostructured hydrogel has been created. The crystalline hydrogels exhibit iridescent patterns that are tunable by the change of temperature, pH value or even protein concentration. This kind of soft and wet hydrogel with periodic structures may lead to new sensors, devices, and displays operating in aqueous solutions, where most biological and biomedical systems reside. The volume-transition equilibrium and the interaction potential between neutral PINPAM particles dispersed in pure water were investigated by using static and dynamic light-scattering experiments. From the temperature-dependent size and energy parameters, the Sutherland-like potential provides a reasonable representation of the inter-particle potential for PNIPAM particles in swollen and in collapsed phases. An aqueous dispersion of PNIPAM particles can freeze at both high and low temperatures. At low temperatures, the freezing occurs at a large particle volume fraction, similar to that in a hard-sphere system; while at high temperature, the freezing occurs at low particle concentrations, driven by the strong van der Waals attraction due to the collapsed microgel particles. The calculated phase diagram has been confirmed semi-quantitatively by experiments.

The invention of electric arc welding revolutionized the steel construction industry, but also brought some problems when the welded region has inferior properties compared to the plate metal. A major cause of brittle failure was identi ed as hydrogen embrittlement of the weld zone, although a comprehensive understanding of this phenomenon is not, even now, available. Hydrogen in solution in the weld zone is found in arc welds, due to the intense conditions in the welding arc. There is invariably a sufficient source in the form of moisture and hydrocarbon residue to give a few parts-per-million (ppm) by mass of hydrogen in the weld pool, which is a sufficient concentration to bring the possibility of hydrogen cold cracking in the completed weld. Hydrogen is significantly mobile in steels at room temperature, which is certainly why a few ppm of hydrogen can concentrate on a microscopic scale and initiate cracks, but also means that on a macroscopic scale there is hydrogen dispersion, which can relieve the cracking risk or place hydrogen in hydrogen cracking susceptible regions. The understanding of solubility and mobility of hydrogen in steels of different compositions and microstructures is therefore paramount. The question investigated in this work is whether the characteristics of the weld hydrogen cracking tendency can be explained by the features of weld hydrogen transport, especially when steel selection is a variable. Plate steel ranging from a 0.22%C pearlitic steel to a 0.05%C thermo-mechanically controlled-rolled and accelerated-cooled (TMCR-AC) high strength low alloy (HSLA) steel with no pearlite, plus a 0.4%C non-plate steel, were included in the experimental program. Welds were made with rutile ux-cored-wire (R-FCW) at two hydrogen levels, together with rutile shielded-metal-arc (R-SMA) welds. In order to investigate the di usion rates, a novel experiment has been devised. The welded plate has been milled away at an angle from the underside of the weld to provide increasing distances between the fusion boundary and the plate under-surface. The formation of hydrogen bubbles in glycerol enabled the measurements of the time dependent diffusion distances. The results clearly show a square root time correlation, as expected from the Fickian mechanism and enabled the calculation of diffusion coefficients for different steels. A nearly four fold difference was found between the steels, with the fastest hydrogen movement in the TMCR-AC steel. To reveal the initial distribution of hydrogen some samples were frozen immediately after welding and machined under liquid nitrogen. This test ruled-out any signi cant hydrogen dispersion during the deposition of the weld and during the cooling down period. The experimental data were interpreted using a new numerical computer model, based on random jumps of hydrogen between equivalent lattice sites. It is shown that this numerical model gives identical results to the analytical Fickian approach, but has the advantage that it can be used for any boundary shape. When this model has been applied to the experimental data, some unexpected features have been found. The amount of hydrogen emerging at surfaces distant to the weld was higher than expected from a concentration-driven mechanism; suggesting that a di erent transport mechanism should be applied. The numerical model has also indicated a discontinuity in the hydrogen concentration at the fusion boundary. It is a consequence of the model that hydrogen solubilities and di usivities are inversely related properties of the metal; a feature which is supported by experimental evidence. The tendency of hydrogen cracking to appear in the weld metal rather than in the heat-a ected-zone (HAZ) can thus be explained by higher di usivity of hydrogen in the plate metal. It appears that there is a relationship between the diffusivity and the microstructure, particularly when the content and form of carbon is considered.

<p>The HIV epidemic in the United States continues to be a significant public health problem, with approximately 50,000 new infections occurring each year. National public health priorities have shifted in recent years towards targeted HIV prevention efforts among people living with HIV/AIDS (PLWHA) that include: increasing engagement in and retention in care, improving HIV treatment adherence, and increasing screening for and treatment of substance use and psychological difficulties. This study evaluated the efficacy of Positive Choices (PC), a brief, care-based, theory-driven, 3-session counseling intervention for newly HIV-diagnosed men who have sex with men (MSM), in the context of current national HIV prevention priorities. The study involved secondary analysis of data from a preliminary efficacy trial of the PC intervention (n=102). Descriptive statistics examined baseline substance use, psychological characteristics and strategies, and care engagement and HIV-related biological outcomes. Generalized Estimating Equations (GEE) examined longitudinal changes in these variables by study condition. Results indicated that PC improved adherence to HIV treatment, but increased use of illicit drugs, specifically amyl nitrates and other stimulant drugs; additionally, moderation analyses indicated differences in patterns of change over time in viral load by baseline depression status. Implications of the findings and suggestions for future research are discussed.</p> / Dissertation

Before vehicles that go to sale for public it goes through many stages of testing in different fields. All types of pre-production cars are the vehicles that come after prototypes which allow the OEM to find out possible issues by running different categories of tests. One of the most important fields of test is regarding safety. When it comes to autonomous cars, where safety is crucial, the number of tests to carry out, time for handling them and their complexity is increased. To reduce costs, complexity and time some of them might be simulated. After the analysis is done the cars have to be tested in real time to collect more data, not only from car sensors but also through observation from the tests filmed. This thesis contains an overview of whole project leading to develop an autonomous platform, driving after autonomous car and controlled by simulation environment and solving major issues of the project. The filming of autonomous cars remotely had two major issues. One of the issues was to integrate all the different software and platforms. The trajectories of the autonomous cars were controlled in different software and the trajectories of the RC were managed in different software. The solution to integrate all the software and platforms is shown in this thesis. The second issue was to make the RC car to follow the waypoints that are generated by simulation and by communicating with real car using a PID controller. The project is prepared for future improvements, like installing a camera to the RC car which will follow predefined test independently.

Com os avanços tecnológicos ocorridos nas últimas décadas, tornou-se possível às diversas áreas do conhecimento melhorar a qualidade e expectativa de vida da população. Dentre as diversas áreas da Engenharia de Materiais, a de Biomateriais é a que está se destacando, vindo ao encontro das necessidades crescentes de melhorar a qualidade de vida da população. O uso de materiais que possam substituir partes ósseas vem sendo motivo de estudos há muitos anos. Para isto, os materiais têm que possuir propriedades químicas e mecânicas semelhantes às do organismo. Materiais como: cerâmicas, polímeros, metais ou até mesmo combinações entre eles vem sendo utilizados como biomateriais. Uma linha de materiais cerâmicos que se destaca é a de produtos à base de alumina, em função de suas características de biocompatibilidade e excelentes propriedades mecânicas. Na medicina, as próteses assumiram um papel importante, tanto na questão estética quanto na funcional. Os desafios nesta área, no intuito de descobrir novos materiais que possam substituir os existentes com desempenho satisfatório e custos mais acessíveis, tornam-se objetos de pesquisa em todo mundo. Na literatura existem poucos trabalhos que correlacionam bioatividade e propriedades mecânicas de cerâmicas à base de alumina, com relação à área médica. Para contribuir nesta questão, propôs-se um estudo tendo como base a alumina. O trabalho tem como objetivo desenvolver cerâmicas a base de alumina porosa, utilizando para isto o hidróxido de alumínio como nucleador de microporos. Resultados obtidos para o material mostram que a porosidade cresce com o aumento da concentração de hidróxido de alumínio na amostra. O preenchimento dos poros da matriz com biovidro tem por objetivo facilitar o processo de osteocondução. A vantagem do processo é a diminuição do tempo de recuperação para o paciente. Os resultados obtidos mostram que a adição de hidróxido de alumínio leva a uma porosidade maior nas amostras. Ensaios realizados verificaram que a concentração máxima de hidróxido é de 20 % em volume, e que concentrações maiores levam os corpos de prova a instabilidade. Os ensaios com o biovidro em forma de gel mostraram-se promissores, devido a facilidade para impregnação nos corpos de prova. Testes de bioatividade in vitro revelaram que o biovidro poderá ser utilizado como material bioativo, revelando um material útil no uso em próteses médicas. / With technological advances in the past decades, it became possible for various areas of knowledge to improve the quality and life expectancy of the population. Among the various areas of Materials Engineering, the Biomaterials is one that is emerging, coming to meet the growing needs to improve the quality of life. The use of materials that can replace bony parts has been subject of study for many years. For this, the materials have to possess chemical and mechanical properties similar to the body. Materials such as ceramics, polymers, metal or even combinations of them have been used as biomaterials. A line of ceramic materials that stands out is that of alumina-based products, due to their biocompatibility and excellent mechanical properties. In medicine, prosthetics played an important role in both aesthetics and functionality. The challenges in this area in order to discover new materials that can replace the existing performance and costs more affordable, they become objects of research worldwide. In the literature there are few studies that correlate bioactivity and mechanical properties of alumina ceramic base with respect to the medical field. To contribute to this issue, a proposed a study based on alumina. The work aims to develop ceramic-based porous alumina, using study has been aluminum hydroxide as nucleator of micropores. Results obtained for the material show that the porosity increases with increasing concentration of aluminum hydroxide in the sample. The filling of pores of the matrix with bioglass aims to facilitate the process of osteoconduction. The advantage of the process is to reduce the recovery time for the patient. The results show that the addition of aluminum hydroxide leads to a higher porosity in the samples. Tests carried out found that the maximum concentration of hydroxide is 20%, and higher concentrations lead to specimens instability. The tests with the bioglass gel have show promising due to ease of impregnation in the specimens. Bioactivity in vitro tests revealed that the bioglass can be used as a bioactive material, revealing a useful material for medical prostheses.

A papaína é uma enzima proteolítica extraída do látex das folhas e frutos do mamão verde adulto. Tem sido amplamente utilizada como agente debridante de escaras e cicatrizante de feridas. No entanto, apresenta baixa estabilidade, o que limita seu uso a formulações de manipulação extemporânea ou de curto prazo de validade. O objetivo deste trabalho foi incorporar a papaína em uma matriz polimérica de modo a obter um sistema de liberação controlada do fármaco. Polímeros de aplicação médica foram selecionados e inicialmente avaliados quanto à sua citotoxicidade. Os polímeros não-citotóxicos foram submetidos ao ensaio de irritação cutânea primária in vivo em animais, para avaliar sua capacidade de causar irritação na pele humana. Diversas membranas foram preparadas com os polímeros considerados adequados para aplicação biomédica para incorporação da papaína. As membranas preparadas com 2% de papaína foram selecionadas para serem submetidas ao ensaio de liberação com células de difusão de Franz. Parte dessas membranas foi irradiada com raios &#947; na dose de 25 kGy para esterilização do material. As membranas irradiadas e não-irradiadas foram testadas simultaneamente a fim de verificar se a radiação &#947; interferiria no perfil de liberação do fármaco. Os resultados do ensaio de liberação indicaram que o fármaco é liberado de maneira constante durante as 12 horas iniciais do experimento. A análise, por Microscopia Eletrônica de Varredura, das membranas irradiadas revelou que as membranas formadas são bastante densas e que seus poros são pequenos. / Papain is a proteolytic enzyme extracted from the latex of green papaya leaves and fruits. It has been widely used as debridant for scars and wound healing agent. However, papain presents low stability, which limits its use to extemporaneous or short shelf life formulations. The purpose of this study was to entrap papain into a polymeric matrix in order to obtain a drug delivery system. Polymers of medical application were selected and firstly assessed for cytotoxicity. Non-cytotoxic polymers were evaluated for primary cutaneous irritation test in vivo in animals, in order to verify if they are able to cause irritation to human skin. Many membranes were prepared with the polymers considered suitable for biomedical application for papain entrapment. Membranes containing 2% papain were selected to be evaluated in the releasing test using Fanz diffusion cells. Some of these membranes were irradiated by &#947; rays with 25 kGy dose for material sterilization. Irradiated and non-irradiated membranes were simultaneously assessed in order to verify if &#947; radiation interferes on drug releasing profile. Results obtained from releasing test indicated the drug is released in a constant manner over 12 hours in the beginning of the experiment. Scanning Eletronic Microscopy analysis of the irradiated membranes revealed that membranes are very dense and its pores are small.

As redes de sensores sem fio (RSSF) ganham maior visibilidade a cada ano, e a sua utilização é cada vez mais imprescindível no sensoriamento dos mais diversos ambientes. Estas redes podem ser instaladas em praticamente todos os tipos de ambientes, graças ao seu tamanho reduzido, sua facilidade de comunicação e seu baixo custo. Esta tecnologia permite transportar os dados através de nós que utilizam algoritmos de roteamento oferecendo resistência a falhas. O conhecimento das principais arquiteturas e dos protocolos envolvidos na comunicação, bem como do comportamento destas redes em ambientes reais, é de extrema importância para a compreensão do funcionamento da rede e dos fenômenos que afetam o seu desempenho. Este trabalho apresenta a utilização de uma RSSF baseada no dispositivo Mica2dot, desenvolvido pela Universidade de Berkeley, no monitoramento de parâmetros ambientais de uma sala limpa utilizada na construção de dispositivos semicondutores. Apresentamos a caracterização dos dispositivos e do ambiente em questão; também avaliamos dois protocolos de roteamento neste ambiente e fatores que afetam o funcionamento do sistema de rádio, como a variação do RSSI (Receive Signal Strength Indicator). Os protocolos de roteamento escolhidos para esta avaliação foram o TOSB (TinyOs Beaconing), que é o protocolo padrão do sistema operacional TinyOS, e o PROC (Proactive ROuting with Coordination), que apresenta características de pró-atividade. Os protocolos foram avaliados segundo as métricas de consumo de energia e taxa média de entrega de pacotes. / Wireless sensor networks (WSNs) are growing year after year, and its use is being more and more indispensable in sensing the most varied environments. These networks can be installed in almost all kinds of environments, thanks to its reduced size, its easiness of communication and its low cost. One of the main characteristics of this technology is the capacity of transporting data through the nodes that use router algorithms, offering a good resistance to failures. The knowledge of the main architectures and of the protocols involved in communication, as well the behavior of these networks in real environments, is of extreme importance to the understanding of the working conditions of the network and of the phenomena that affect its performance. This piece of work aims to present a study related to the use of a WSN based on the Mica2dot device developed by the University of Berkeley, in the monitoring of the environmental parameters of a clean room used to the construction of semiconductor devices. This work presents the characterization of the devices and of the environment in question, as well evaluates some factors that affect the working of the radio system and evaluates two router protocols in this environment. The chosen router protocols for this evaluation were TOSB (TinyOs Beaconing) that is the standard protocol of the operational system TinyOS, and PROC (Proactive Routing with Coordination), that presents some pro-active characteristics. The protocols were evaluated according to the measurement of the energy consumption and average rate of deliver of packages.

This dissertation is directed towards the fundamental understanding of the controlled synthesis of noble-metal (silver, gold, and palladium) and metal oxide (manganese and copper oxide) nanostructures as well as their applications in heterogeneous and plasmonic catalysis. In the first part of this work (Section 1), we provided a general background concerning the science of controlled nanomaterials, their syntheses, properties, and applications in catalysis and plasmonic catalysis. Then, we describe and developed a series of protocols for the synthesis of these nanomaterials with controlled sizes and structures (spheres, cubes, rods, shells, flowers, dendrites, and tadpoles), mainly focusing on the mechanistic understanding of their formation and how physical and chemical parameters (size, shape, composition, surface morphology) may influence/modify their catalytic properties (Sections 2 and 3). In Section 4, we turned our attention for the design of simple protocols for the synthesis of advanced nanomaterials that are interesting for green catalytic transformations applications. In this case, we envisioned the use of MnO2-Au nanomaterials (nanowires and nanoflowers) displaying several properties (unique pore structure, high surface area, ultrasmall Au NPs at the surface, high concentration of oxygen vacancies and Au&#948;+ species, strong metal-support interactions, and uniform shapes and sizes) that are desirable for catalyzing a series of green oxidation reactions in mild conditions (low temperatures and molecular oxygen or atmospheric air as the oxidants). In Section 5, we have demonstrated that catalysis and optical properties can be merged together to improve catalytic processes, the so called-plasmonic catalysis. This allowed us the use of visible light as the energy input to drive chemical transformations in mild conditions and then provide new insights regarding the various factors that affect SPR-mediated catalytic activities in plasmonic nanostructures. Finally, in Section 6, we focused our attention on how important is to introduce both nanoscience and the synthesis/characterization of nanomaterials having controlled physicochemical features to undergraduate students. Specifically, we have described simple laboratory experiments for the synthesis of nanomaterials (gold nanospheres and Cu(OH)2/CuO nanowires) displaying uniform sizes and shapes in order to investigate and explain their optical properties, catalytic activities and formation mechanisms. / Não consta resumo na publicação.

Com os avanços tecnológicos ocorridos nas últimas décadas, tornou-se possível às diversas áreas do conhecimento melhorar a qualidade e expectativa de vida da população. Dentre as diversas áreas da Engenharia de Materiais, a de Biomateriais é a que está se destacando, vindo ao encontro das necessidades crescentes de melhorar a qualidade de vida da população. O uso de materiais que possam substituir partes ósseas vem sendo motivo de estudos há muitos anos. Para isto, os materiais têm que possuir propriedades químicas e mecânicas semelhantes às do organismo. Materiais como: cerâmicas, polímeros, metais ou até mesmo combinações entre eles vem sendo utilizados como biomateriais. Uma linha de materiais cerâmicos que se destaca é a de produtos à base de alumina, em função de suas características de biocompatibilidade e excelentes propriedades mecânicas. Na medicina, as próteses assumiram um papel importante, tanto na questão estética quanto na funcional. Os desafios nesta área, no intuito de descobrir novos materiais que possam substituir os existentes com desempenho satisfatório e custos mais acessíveis, tornam-se objetos de pesquisa em todo mundo. Na literatura existem poucos trabalhos que correlacionam bioatividade e propriedades mecânicas de cerâmicas à base de alumina, com relação à área médica. Para contribuir nesta questão, propôs-se um estudo tendo como base a alumina. O trabalho tem como objetivo desenvolver cerâmicas a base de alumina porosa, utilizando para isto o hidróxido de alumínio como nucleador de microporos. Resultados obtidos para o material mostram que a porosidade cresce com o aumento da concentração de hidróxido de alumínio na amostra. O preenchimento dos poros da matriz com biovidro tem por objetivo facilitar o processo de osteocondução. A vantagem do processo é a diminuição do tempo de recuperação para o paciente. Os resultados obtidos mostram que a adição de hidróxido de alumínio leva a uma porosidade maior nas amostras. Ensaios realizados verificaram que a concentração máxima de hidróxido é de 20 % em volume, e que concentrações maiores levam os corpos de prova a instabilidade. Os ensaios com o biovidro em forma de gel mostraram-se promissores, devido a facilidade para impregnação nos corpos de prova. Testes de bioatividade in vitro revelaram que o biovidro poderá ser utilizado como material bioativo, revelando um material útil no uso em próteses médicas. / With technological advances in the past decades, it became possible for various areas of knowledge to improve the quality and life expectancy of the population. Among the various areas of Materials Engineering, the Biomaterials is one that is emerging, coming to meet the growing needs to improve the quality of life. The use of materials that can replace bony parts has been subject of study for many years. For this, the materials have to possess chemical and mechanical properties similar to the body. Materials such as ceramics, polymers, metal or even combinations of them have been used as biomaterials. A line of ceramic materials that stands out is that of alumina-based products, due to their biocompatibility and excellent mechanical properties. In medicine, prosthetics played an important role in both aesthetics and functionality. The challenges in this area in order to discover new materials that can replace the existing performance and costs more affordable, they become objects of research worldwide. In the literature there are few studies that correlate bioactivity and mechanical properties of alumina ceramic base with respect to the medical field. To contribute to this issue, a proposed a study based on alumina. The work aims to develop ceramic-based porous alumina, using study has been aluminum hydroxide as nucleator of micropores. Results obtained for the material show that the porosity increases with increasing concentration of aluminum hydroxide in the sample. The filling of pores of the matrix with bioglass aims to facilitate the process of osteoconduction. The advantage of the process is to reduce the recovery time for the patient. The results show that the addition of aluminum hydroxide leads to a higher porosity in the samples. Tests carried out found that the maximum concentration of hydroxide is 20%, and higher concentrations lead to specimens instability. The tests with the bioglass gel have show promising due to ease of impregnation in the specimens. Bioactivity in vitro tests revealed that the bioglass can be used as a bioactive material, revealing a useful material for medical prostheses.

A papaína é uma enzima proteolítica extraída do látex das folhas e frutos do mamão verde adulto. Tem sido amplamente utilizada como agente debridante de escaras e cicatrizante de feridas. No entanto, apresenta baixa estabilidade, o que limita seu uso a formulações de manipulação extemporânea ou de curto prazo de validade. O objetivo deste trabalho foi incorporar a papaína em uma matriz polimérica de modo a obter um sistema de liberação controlada do fármaco. Polímeros de aplicação médica foram selecionados e inicialmente avaliados quanto à sua citotoxicidade. Os polímeros não-citotóxicos foram submetidos ao ensaio de irritação cutânea primária in vivo em animais, para avaliar sua capacidade de causar irritação na pele humana. Diversas membranas foram preparadas com os polímeros considerados adequados para aplicação biomédica para incorporação da papaína. As membranas preparadas com 2% de papaína foram selecionadas para serem submetidas ao ensaio de liberação com células de difusão de Franz. Parte dessas membranas foi irradiada com raios &#947; na dose de 25 kGy para esterilização do material. As membranas irradiadas e não-irradiadas foram testadas simultaneamente a fim de verificar se a radiação &#947; interferiria no perfil de liberação do fármaco. Os resultados do ensaio de liberação indicaram que o fármaco é liberado de maneira constante durante as 12 horas iniciais do experimento. A análise, por Microscopia Eletrônica de Varredura, das membranas irradiadas revelou que as membranas formadas são bastante densas e que seus poros são pequenos. / Papain is a proteolytic enzyme extracted from the latex of green papaya leaves and fruits. It has been widely used as debridant for scars and wound healing agent. However, papain presents low stability, which limits its use to extemporaneous or short shelf life formulations. The purpose of this study was to entrap papain into a polymeric matrix in order to obtain a drug delivery system. Polymers of medical application were selected and firstly assessed for cytotoxicity. Non-cytotoxic polymers were evaluated for primary cutaneous irritation test in vivo in animals, in order to verify if they are able to cause irritation to human skin. Many membranes were prepared with the polymers considered suitable for biomedical application for papain entrapment. Membranes containing 2% papain were selected to be evaluated in the releasing test using Fanz diffusion cells. Some of these membranes were irradiated by &#947; rays with 25 kGy dose for material sterilization. Irradiated and non-irradiated membranes were simultaneously assessed in order to verify if &#947; radiation interferes on drug releasing profile. Results obtained from releasing test indicated the drug is released in a constant manner over 12 hours in the beginning of the experiment. Scanning Eletronic Microscopy analysis of the irradiated membranes revealed that membranes are very dense and its pores are small.