Os implantes dentários de titânio comercialmente puro (Ticp) grau 4 e os de titânio-alumínio-vanádio (Ti6Al4V) grau 5, possuem boas propriedades mecânicas. No entanto, algumas situações clínicas com restrição de espessura óssea impedem a utilização dos implantes com 3.75mm de diâmetro tradicionalmente fabricados em titânio 4 e que apresentam resistência mecânica testada em profusão. Como a liga de grau 5 possui superior resistência à tração e à fadiga, este estudo objetiva analisar a resposta óssea do titânio grau 4 e grau 5 em implantes curtos e estreitos através da análise do contato osso-implante (BIC) e da área de neoformação óssea. Para este fim, o presente estudo utilizou 15 coelhos da raça New Zealand, que receberam um total de trinta implantes divididos em suas tíbias direita e esquerda. Os implantes de grau 4 e de grau 5, com dimensões de 3.5x8mm e 2.9x7mm, respectivamente, foram fornecidos pela empresa NEODENT® (Curitiba-Brasil). Neste estudo, dois grupos foram formados, um com implantes de titânio grau 4 e outro com implantes de titânio grau 5, ambos contendo quinze implantes curtos e estreitos. Cortes histológicos foram realizados após duas semanas de osseointegração. Mensurações no analisador de imagens ImageJ foram feitas para verificar o BIC e a área de osso neoformado. Para a análise dos dados estatísticos, utilizou-se o teste t de Student para amostras independentes com nível de significância de p<0.05. Os resultados mostraram que não houve diferença estatisticamente significante entre os grupos nos dois tipos de análises. A média dos valores de BIC do titânio grau 4 obteve o valor médio mais alto de 56,53%, variando de 95,74% a 9,4%. O grupo de titânio grau 5 apresentou média de 50,63%, variando entre 84,3% e 13,12%. Com base em imagens com fluorescência, realizou-se análise da área óssea. O grupo de titânio grau 5 apresentou valor de 46,3% (variando entre 79% a 14,21%) em fluorescência, número ligeiramente maior do que o verificado no grupo de titânio grau 4 (44,73%, com variância entre 78,93% e 18,36%). Com isso, concluiu-se que implantes de titânio de grau 4 e de grau 5 obtiveram respostas biológicas equivalentes, quando avaliados o BIC e a área óssea neoformada. / Commercially pure titanium implants (Ticp) of degree IV and of titanium-aluminum-vanadium degree V have good mechanical properties. However some clinical situations with limited bone thickness preclude the use of traditionally implants with 3.75mm diameter made from titanium IV and present strength tested in profusion. In addition, degree V alloy shows higher resistance to traction and fatigue, this study aims to analyze the bone response to degree IV and degree V titanium in short and narrow implants with the same surface treatment through the analysis of the bone-to-implant contact (BIC) and the area of the new bone formation. For such purpose, this study used15 New Zealand white rabbits which had a total of thirty implants inserted in their right and left tibiae. Both degree IV and degree V implants, measuring 3.5x8mm and 2.9x7mm, respectively, were provided by dental implant manufacturer NEODENT® (Curitiba-Brazil). The implants were allocated into two distinct groups. Fifteen short and narrow implants of degree IV were utilized in a group, whereas fifteen short and narrow implants of degree V were employed in the other group. Histological sections samples were carried out after a two-week period of osseointegration. Subsequently, measurements were calculated using ImageJ software in order to verify the BIC and the area of the newly grown bone. Analysis of statistical data of independent samples with significance level p<0.05 was carried out via Student\'s t-test. Results showed no statistically substantial difference between both groups regarding both measurement activities. The media values BIC for the degree IV titanium group reached the highest average value of 56,53%, varying from 95,74% to 9,4%. The degree V titanium group averaged 50,63%, oscillating between 84,3% and 13,12%. The bone areas were analyzed based on images with fluorescence. The degree V titanium group reached the percentage of 46,3% (varying from 79% to 14,21%) in fluorescence whereas the degree IV titanium group had a percentage of 44,73% (varying between 78,93% and 18,36%). Therefore, both degree IV and degree V implants had equivalent biological responses based on the analysis of BIC and newly grown bone areas.

Os fornos de pirólise, feitos a partir da liga HP modificada, são equipamentos destinados à produção de hidrocarbonetos leves na indústria petroquímica. A partir da pirólise, é possível obter etileno e outros produtos que são matérias-primas para obtenção de manufaturados formados por polímeros. Nesse processo, grandes moléculas de hidrocarbonetos, na forma gasosa, são craqueadas em condições especiais de temperatura e pressão. Durante o craqueamento, o teor de carbono dos materiais que constituem os fornos é aumentado por meio do ingresso de carbono através da superfície interna dos tubos, sendo oriundo da massa reativa que atravessa as colunas e, como consequência disso, ocorre uma alteração das propriedades mecânicas do material. Aliado a esse fato, existe o depósito nocivo de uma camada de coque a partir da superfície interna das tubulações, que funciona como um isolante térmico, diminuindo a temperatura do gás e exigindo uma maior temperatura de trabalho para o forno, além de causar tensões que podem resultar em trincas ou danos para as colunas dos fornos de pirólise. Durante a carburização, a liga metálica dos fornos de pirólise desenvolve propriedades tipo ferromagnéticas, as quais são resultado do processo de ingresso de carbono. Nesta etapa, a camada magnetizada do material coincide com a região onde houve propagação da carburização. Sendo assim, uma medida da magnetização do material pode resultar em uma medida direta do nível de carburização em que o forno se encontra. Neste trabalho, serão apresentadas técnicas para simulação de ambientes carburizantes em alta temperatura, e as amostras serão testadas tendo o tempo de exposição ao carbono como sua principal variável e as suas propriedades mecânicas serão avaliadas, além da alteração de sua composição química e sua microestrutura. / The pyrolysis heaters, made of HP-modified alloy, are equipments designed to produce lightweight hydrocarbon in the petrochemical industry. Because of the pyrolysis, it is possible to obtain ethylene and other products that are raw material to gain manufactured polymer. In this process, big gaseous hydrocarbon molecules suffer a cracking process under special conditions of temperature and pressure. During the steam cracking process, the amount of carbon from the constituent material of the heaters is increasing as a consequence of the carbon entrance through the inside surface of the tubes. This carbon comes from the reactive mass that crows the columns and, eventually, produces a change in the mechanical proprieties of the material. Besides that, there is a harmful deposit of a coke layer that comes from the internal surface of the heater tubes. This layer works as a thermal insulation and is responsible for the decreasing of the gas temperature and as a consequence, the heater demands a higher temperature to work properly. As a result, rupture or damages can occur in the pyrolysis heater columns. During the carburization, the above mentioned alloy presents magnetic properties in consequence of the increase of the carbon amount in the material. The magnetic layer is observed in the region where the carburization process happened. Therefore, a measure of the material magnetization can lead to a direct measure of the carburization level in which the heater is on. In this work, simulation techniques of the carburizing environment under high temperature will be presented, and the samples will be tested regarding the correlation between carbon exposition time and the mechanical properties, microstructural changes and chemical composition that occur as a result.

O desenvolvimento de trabalhos relacionados à compreensão do fenômeno de limiar de fadiga ou fator de intensidade de tensão limite (&#916K0), tem possibilitado a aplicação de medidas de segurança para evitar acidentes ou perdas. Estas medidas vão desde a avaliação e substituição de peças contendo falhas até o estabelecimento de prazos entre inspeções. O conhecimento mais aprofundado dos mecanismos que induzem ou promovem o fechamento de trinca por fadiga, auxilia na avaliação dos resultados obtidos para &#916K0 e permite o conhecimento mais preciso deste valor, introduzindo o parâmetro &#916K0,ef. Estudou-se o crescimento de trinca por fadiga para a liga aeronáutica 7050-T73651 com decaimento de &#916K para determinação de &#916K0. Foi considerado o efeito de fechamento de trinca para se verificar o valor de &#916K0,ef para a orientação de laminação LT. Foi verificada a eficiência das equações de Priddle e de Donahue para se prever o comportamento da curva da/dN versus &#916K em função dos parâmetros da equação de Paris e características do material. / The recent development of works on the fatigue threshold phenomenon has provided powerful knowledge applicable to reliability practices such as the replacement of parts or the establishment of periods between inspections. A better understanding of the mechanisms leading to fatigue crack closure has permitted investigators to describe more accurately &#916K0 values, thus introducing a new &#916K0,eff parameter. In this work, fatigue crack growth was carried out on the aeronautics aluminum alloy 7050-T73651 with &#916K decreasing in order to determine &#916K0. Fatigue crack closure effects were considered as to verify the &#916K0,eff value for the LT direction. The ability of the equation of Priddle and that of Donahue to predict the behaviour of da/dN versus &#916K curves based on the parameters m and C from Paris equation and on the materials characteristics was verified.

Estágio realizado na Extrusal - Companhia Portuguesa de Extrusão, S. A. e orientado pelo Eng.ª Margarida Martins / Tese de mestrado integrado. Engenharia Metalúrgica e de Materiais. Faculdade de Engenharia. Universidade do Porto. 2009

Trabalho realizado na Ferespe-Fundição de Ferro e Aço. Lda. e orientado pelo Engº Pedro Lacerda / Tese de mestrado. Engenharia Metalúrgica e de Materiais. Faculdade de Engenharia. Universidade do Porto. 2012

There are a significant number of microwave applications, where improvement of such qualities as manufacturing costs, size, weight, power consumption, etc. have attracted much research interest. In order to meet these requirements, new technologies can be actively involved in fabrication of microwave components with improved characteristics. One such fabrication technology is called LIGA (a German acronym with an English translation of lithography, electroforming, and moulding) that allows fabrication of high aspect ratio (tall) structures, and only recently is receiving growing attention in microwave component fabrication.<p> The characteristics of high aspect ratio microstrip and coplanar waveguide (CPW) transmission lines are investigated in this thesis. Very low impedance high aspect ratio CPW transmission lines can be realized. A high aspect ratio microstrip folded half wavelength open loop resonator is introduced. Effective configurations for external and bypass gap coupling with open loop resonators are given. Filters with transmission zeros in the stopband, consisting of high aspect ratio single mode open loop resonators are presented to demonstrate the advantages of high aspect ratio structures in realizing lower external quality factors or tight coupling. The transmission zeros are created by novel coupling routings. Some of the filters are fabricated and the filter responses are measured to validate high aspect ratio coupling structures. High aspect ratio diplexers with increased channel isolation are also designed by appropriately combining filters with transmission zeros.<p> A wideband bandpass filter design method, based on the electromagnetic bandgap (EBG) concept is introduced in this thesis. The wideband filters are miniaturized as a result of using the EBG concept in design. An EBG based wideband filter consisting of unit cells that are realized by using high aspect ratio CPW stepped impedance resonators is also presented. The main advantage of this approach is that the high aspect ratio CPW structures make short unit cells practically realizable, resulting in compact filter structure.

There are a significant number of microwave applications, where improvement of such qualities as manufacturing costs, size, weight, power consumption, etc. have attracted much research interest. In order to meet these requirements, new technologies can be actively involved in fabrication of microwave components with improved characteristics. One such fabrication technology is called LIGA (a German acronym with an English translation of lithography, electroforming, and moulding) that allows fabrication of high aspect ratio (tall) structures, and only recently is receiving growing attention in microwave component fabrication.<p> The characteristics of high aspect ratio microstrip and coplanar waveguide (CPW) transmission lines are investigated in this thesis. Very low impedance high aspect ratio CPW transmission lines can be realized. A high aspect ratio microstrip folded half wavelength open loop resonator is introduced. Effective configurations for external and bypass gap coupling with open loop resonators are given. Filters with transmission zeros in the stopband, consisting of high aspect ratio single mode open loop resonators are presented to demonstrate the advantages of high aspect ratio structures in realizing lower external quality factors or tight coupling. The transmission zeros are created by novel coupling routings. Some of the filters are fabricated and the filter responses are measured to validate high aspect ratio coupling structures. High aspect ratio diplexers with increased channel isolation are also designed by appropriately combining filters with transmission zeros.<p> A wideband bandpass filter design method, based on the electromagnetic bandgap (EBG) concept is introduced in this thesis. The wideband filters are miniaturized as a result of using the EBG concept in design. An EBG based wideband filter consisting of unit cells that are realized by using high aspect ratio CPW stepped impedance resonators is also presented. The main advantage of this approach is that the high aspect ratio CPW structures make short unit cells practically realizable, resulting in compact filter structure.

Dramatic advances are taking place in the microelectronic industry. The feature size continues to scale down and it is expected that the minimum feature size on the integrated circuit is expected to reach 9 nm by 2016, and there will be more than 8 billion transistors on a 310 cm² chip, according to various available roadmaps. Subsequently, this reduction in feature size would require the first-level input-output interconnects to decrease in pitch size to meet the increased number of transistors on the chip. Also, to minimize the on-chip interconnect delay, development of low-K dielectric/copper will become increasingly common in future devices. However, due to the low fracture strength of low-K dielectric, it is essential that the first-level interconnects exert minimal force on the die pads and therefore, do not crack or delaminate the low-K dielectric material. It is also preferable to have a wafer-level packaging approach to facilitate test-and-burn in and to produce known-good dies. Based on these growing demands from the microelectronics industry, there is a compelling need to develop innovative interconnect technologies. This thesis aims to develop one such innovative interconnect — G-Helix interconnect. G-Helix is a scalable lithography-based wafer-level electroplated compliant interconnect that has the potential to meet the fine-pitch first-level chip-to-substrate interconnect requirements. The three-mask fabrication of G-Helix is based on lithography, electroplating and molding (LIGA-like) technologies, and this fabrication can be easily integrated into large-area wafer-level fine-pitch batch processing. In this work, the fabrication, assembly, experimental reliability testing, and numerical physics-based modeling of the G-Helix interconnects will be presented. The fabrication of the interconnects will be demonstrated at 100μm pitch on a 20 x 20 mm die in a class 10/1000 cleanroom facility. The wafers with compliant interconnects will be singulated into individual dies and assembled on substrates using Pb/Sn eutectic solder. The assembly will then be subjected to air-to-air thermal cycling between 0℃and 100℃ and the reliability of the compliant interconnect will be assessed. In addition to the thermo-mechanical reliability testing, some of the dies with free-standing interconnects will also be used for measuring the compliance of the interconnects by compressing with a nanoindenter. In parallel to the experimental research, a numerical analysis study will also be carried out. The numerical model will use direction-, temperature, time-dependent, and time independent material constitutive properties as appropriate. The thermo-mechanical fatigue life of the compliant interconnect assembly will be determined and compared with the experimental data. Recommendations will be developed for further enhancement of reliability and reduction in pitch size.

The current tools for geometric analysis of micro-electromechanical systems (MEMS) are primarily limited to those of the semiconductor industry. These tools are suited for measuring entities that are two-dimensional in nature such as lines, circles, and planes. Hardware that is capable of collecting three-dimensional data is typically limited by the slope variations in the surfaces of the part, and cannot accurately capture information from steep sidewalls, particularly in parts fabricated using the LIGA micro-fabrication process. This research develops a methodology to qualify MEMS, by implementing a novel computer-aided inspection (CAI) software framework. This software platform uses data acquired from current MEMS inspection hardware, and applies newly developed analysis algorithms to geometrically characterize a part. This work implements algorithms for all the procedures typical to a CAI program (e.g., point-to-entity assignment, registration, and data analysis) in addition to new techniques suited for inspection of high aspect ratio MEMS. This methodology describes possible registration errors based on the type of geometries being analyzed and the type of data acquired. Analyses of multiple point clouds with the use of fiducial information are shown to provide a critical link between single point cloud analyses that has heretofore been unrealized.

SUMMARY Relevance and novelty of the topic. Cargivers of persons with clinical dementia experience a lot of social, psychological and physical health problems and feel burdened. Until recently there has been very little analysis of stress factors influencing the caregivers stress. Aim of the study. To measure and examine psychosocial stress of family members and relatives who are caregivers of persons with dementia at home. Methods. Caregivers of persons with dementia filled out an anonymous qeustionaire. The interviews were conducted from December, 2004 to February, 2005. Respondents, who participated in research, were members of Kaunas and Vilnius Alzheimer’s clubs, and the data was collected during the meetings of these two clubs in Kaunas Dainava Center for Psychological Health and Vilnius Antakalnis health centre respectively. 22 respondents were from Kaunas and 28 from Vilnius. From the 50 respondents, who participated in research, 35 (70%) were women, and 15 (30%) were men. The average age was 62 years (the range of age was 40-94 years). The questionnaire that was used to gather data consisted of five parts: general questions about the caregiver and the person with clinical dementia; Greene’s Relatives Stress Scale, Clinical Dementia Rating Scale and Rapid Disability Rating Scale. Results. 7 (14%) respondents experienced a low level of psychosocial stress, 30 (60%) – average, and 13 (26%) – high level of stress. Most often the caregiver for person with clinical... [to full text]