Correlation between the mechanical cycling behavior and microstructure in laser welded joints using NiTi memory shape alloys

Dissertação para obtenção do Grau de Mestre em Engenharia de Materiais

Robustness of timber structures in seismic areas

Some of the properties sought in seismic design of buildings are also considered fundamental to guarantee structural robustness. Moreover, some key concepts are common to both seismic and robustness design. In fact, both analyses consider events with a very small probability of occurrence, and consequently, a significant level of damage is admissible. As very rare events,in both cases, the actions are extremely hard to quantify. The acceptance of limited damage requires a system based analysis of structures, rather than an element by element methodology, as employed for other load cases. As for robustness analysis, in seismic design the main objective is to guarantee that the structure survives an earthquake, without extensive damage. In the case of seismic design, this is achieved by guaranteeing the dissipation of energy through plastic hinges distributed in the structure. For this to be possible, some key properties must be assured, in particular ductility and redundancy. The same properties could be fundamental in robustness design, as a structure can only sustain significant damage if capable of distributing stresses to parts of the structure unaffected by the triggering event. Timber is often used for primary load‐bearing elements in single storey long‐span structures for public buildings and arenas, where severe consequences can be expected if one or more of the primary load bearing elements fail. The structural system used for these structures consists of main frames, secondary elements and bracing elements. The main frame, composed by columns and beams, can be seen as key elements in the system and should be designed with high safety against failure and under strict quality control. The main frames may sometimes be designed with moment resisting joints between columns and beams. Scenarios, where one or more of these key elements, fail should be considered at least for high consequence buildings. Two alternative strategies may be applied: isolation of collapsing sections and, provision of alternate load paths [1]. The first one is relatively straightforward to provide by deliberately designing the secondary structural system less strong and stiff. Alternatively, the secondary structural system and the bracing system can be design so that loss of capacity in the main frame does not lead to the collapse. A case study has been selected aiming to assess the consequences of these two different strategies, in particular, under seismic loads.

Ankylosing spondylitis: genomic and functional characterization of candidate genes and their repercussion in clinical practice

RESUMO: Introdução: A espondilite anquilosante (EA) é uma doença inflamatória crónica caracterizada pela inflamação das articulações sacroilíacas e da coluna. A anquilose progressiva motiva uma deterioração gradual da função física e da qualidade de vida. O diagnóstico e o tratamento precoces podem contribuir para um melhor prognóstico. Neste contexto, a identificação de biomarcadores, assume-se como sendo muito útil para a prática clínica e representa hoje um grande desafio para a comunidade científica. Objetivos: Este estudo teve como objetivos: 1 - caracterizar a EA em Portugal; 2 - investigar possíveis associações entre genes, MHC e não-MHC, com a suscetibilidade e as características fenotípicas da EA; 3 - identificar genes candidatos associados a EA através da tecnologia de microarray. Material e Métodos: Foram recrutados doentes com EA, de acordo com os critérios modificados de Nova Iorque, nas consultas de Reumatologia dos diferentes hospitais participantes. Colecionaram-se dados demográficos, clínicos e radiológicos e colhidas amostras de sangue periférico. Selecionaram-se de forma aleatória, doentes HLA-B27 positivos, os quais foram tipados em termos de HLA classe I e II por PCR-rSSOP. Os haplótipos HLA estendidos foram estimados pelo algoritmo Expectation Maximization com recurso ao software Arlequin v3.11. As variantes alélicas dos genes IL23R, ERAP1 e ANKH foram estudadas através de ensaios de discriminação alélica TaqMan. A análise de associação foi realizada utilizando testes da Cochrane-Armitage e de regressão linear, tal como implementado pelo PLINK, para variáveis qualitativas e quantitativas, respetivamente. O estudo de expressão génica foi realizado por Illumina HT-12 Whole-Genome Expression BeadChips. Os genes candidatos foram validados usando qPCR-based TaqMan Low Density Arrays (TLDAs). Resultados: Foram incluídos 369 doentes (62,3% do sexo masculino, com idade média de 45,4 ± 13,2 anos, duração média da doença de 11,4 ± 10,5 anos). No momento da avaliação, 49,9% tinham doença axial, 2,4% periférica, 40,9% mista e 7,1% entesopática. A uveíte anterior aguda (33,6%) foi a manifestação extra-articular mais comum. Foram positivos para o HLA-B27, 80,3% dos doentes. Os haplótipo A*02/B*27/Cw*02/DRB1*01/DQB1*05 parece conferir suscetibilidade para a EA, e o A*02/B*27/Cw*01/DRB1*08/DQB1*04 parece conferir proteção em termos de atividade, repercussão funcional e radiológica da doença. Três variantes (2 para IL23R e 1 para ERAP1) mostraram significativa associação com a doença, confirmando a associação destes genes com a EA na população Portuguesa. O mesmo não se verificou com as variantes estudadas do ANKH. Não se verificou associação entre as variantes génicas não-MHC e as manifestações clínicas da EA. Foi identificado um perfil de expressão génica para a EA, tendo sido validados catorze genes - alguns têm um papel bem documentado em termos de inflamação, outros no metabolismo da cartilagem e do osso. Conclusões: Foi estabelecido um perfil demográfico e clínico dos doentes com EA em Portugal. A identificação de variantes génicas e de um perfil de expressão contribuem para uma melhor compreensão da sua fisiopatologia e podem ser úteis para estabelecer modelos com relevância em termos de diagnóstico, prognóstico e orientação terapêutica dos doentes. -----------ABSTRACT: Background: Ankylosing Spondylitis (AS) is a chronic inflammatory disorder characterized by inflammation in the spine and sacroiliac joints leading to progressive joint ankylosis and in progressive deterioration of physical function and quality of life. An early diagnosis and early therapy may contribute to a better prognosis. The identification of biomarkers would be helpful and represents a great challenge for the scientific community. Objectives: The present study had the following aims: 1- to characterize the pattern of AS in Portuguese patients; 2- to investigate MHC and non-MHC gene associations with susceptibility and phenotypic features of AS and; 3- to identify candidate genes associated with AS by means of whole-genome microarray. Material and Methods: AS was defined in accordance to the modified New York criteria and AS cases were recruited from hospital outcares patient clinics. Demographic and clinical data were recorded and blood samples collected. A random group of HLA-B27 positive patients and controls were selected and typed for HLA class I and II by PCR-rSSOP. The extended HLA haplotypes were estimated by Expectation Maximization Algorithm using Arlequin v3.11 software. Genotyping of IL23R, ERAP1 and ANKH allelic variants was carried out with TaqMan allelic discrimination assays. Association analysis was performed using the Cochrane-Armitage and linear regression tests as implemented in PLINK, for dichotomous and quantitative variables, respectively. Gene expression profile was carried out using Illumina HT-12 Whole-Genome Expression BeadChips and candidate genes were validated using qPCR-based TaqMan Low Density Arrays (TLDAs). Results: A total of 369 patients (62.3% male; mean age 45.4±13.2 years; mean disease duration 11.4±10.5 years), were included. Regarding clinical disease pattern, at the time of assessment, 49.9% had axial disease, 2.4% peripheral disease, 40.9% mixed disease and 7.1% isolated enthesopathic disease. Acute anterior uveitis (33.6%) was the most common extra-articular manifestation. 80.3% of AS patients were HLA-B27 positive. The haplotype A*02/B*27/Cw*02/DRB1*01/DQB1*05 seems to confer susceptibility to AS, whereas A*02/B*27/Cw*01/DRB1*08/DQB1*04 seems to provide protection in terms of disease activity, functional and radiological repercussion. Three markers (two for IL23R and one for ERAP1) showed significant single-locus disease associations. Association of these genes with AS in the Portuguese population was confirmed, whereas ANKH markers studied did not show an association with AS. No association was seen between non-MHC genes and clinical manifestations of AS. A gene expression signature for AS was established; among the fourteen validated genes, a number of them have a well-documented inflammatory role or in modulation of cartilage and bone metabolism. Conclusions: A demographic and clinical profile of patients with AS in Portugal was established. Identification of genetic variants of target genes as well as gene expression signatures could provide a better understanding of AS pathophysiology and could be useful to establish models with relevance in terms of susceptibility, prognosis, and potential therapeutic guidance.

Contributo para o desenvolvimento de uma metodologia que avalia a posição da omoplata: fidedignidade intra e interobservador e validade concorrente

RESUMO: Introdução: A relação cinemática entre as articulações do CAO apresenta grande importância na função do MS, e é por isso cada vez mais investigada e descrita. O posicionamento da omoplata ganha um importante papel para compreender as DCAO. É indiscutível o importante papel da omoplata na dinâmica do MS, bem como o posicionamento escapular como parâmetro clínico de disfunção do CAO. Todos estes factores criam a necessidade de desenvolver instrumentos de avaliação da posição da articulação ET. A grande maioria dos testes de avaliação, restringem a sua avaliação às disfunções da articulação GU, não integrando uma avaliação mais dinâmica e interactiva que respeite os pressupostos teóricos inerentes ao REU. È importante também que os métodos de avaliação sejam de fácil aplicabilidade clínica e que avaliem fidedignamente e com validade os outcomes. Objectivos: Contribuir para o desenvolvimento de uma metodologia de avaliação da omoplata em diferentes amplitudes do MS, através do estudo da validade concorrente, da fidedignidade intra e inter-observador. Metodologia: A amostra foi constituída por 20 elementos seleccionados por conveniência, entre o corpo de discentes da ESS-IPS, sem história de disfunção do CAO. Foi realizada uma análise cinemática ao MS de cada sujeito, usando um aparelho de análise por varrimento electromagnético, o FOB. Em cada sujeito foram ainda medidas, as distâncias escapulares em estudo, usando a fita métrica. Cada método de medição foi constituído por dois momento (teste e reteste), em cada momento, as medidas eram recolhidas por dois investigadores distintos. Resultados e Discussão: Foram considerados como positivos os resultados que se apresentassem acima do limiar de 0,5, que classifica uma correlação como moderada a excelente. Os resultados da validade mostram que para o investigador 1 nas medidas M1e M2 apenas houve correlação com valores excelentes a moderados até aos 30º de elevação do MS. Já para M3 apenas aos 30º no plano da omoplata essa mesma correlação não tem valores próximos do cutpoint. Em M4 nenhum valor tem correlação significativa com os valores do FOB, chegando mesmo a haver correlação negativa para os 120º no plano da omoplata. Em M5 apenas os 0º mostram valores correlacionais excelentes a moderados. Para o investigador 2, em M1 e M2 á semelhança do investigador 1, só existem valores de correlação significativos até aos 30º de elevação do MS. Já para M3 todos os valores mostram excelente a moderada correlação á excepção dos 120º no plano frontal. Em M4 este investigador apresenta maus resultados. Já em M5 os valores de correlação são moderados aos 0º e aos 90º. No que diz respeitos aos resultados dos CCI intra-observador,podemos afirmar que foi em M5 que estes valores mais se aproximaram do cut point. M1 e M2 são as medidas onde se encontram resultados menos satisfatórios. É aos 60º que existem valores mais satisfatórios, seguidos pelos 0º e 30º, quando nos aproximamos de graus mais elevados, como 90º e 120º, estes valores tendem a baixar. Quanto á fidedignidade inter-observador para M1 apenas aos 90º e aos 120º houve valores de correlação abaixo do cutpoint. Em M2, só os 60º do plano sagital não teve valores acima do cutpoint, em M3 apenas os 30º plano sagital não obtiveram valores acima do cut-point, o mesmo acontece para M3 aos 30º plano da omoplata e em M5 aos 30º e 120º no plano frontal. Conclusão: Os resultados deste estudo indicam que a metodologia em causa apresenta elevado grau de fidedignidade inter-observador, já no que toca é fidedignidade intra-observador o grau de semelhança não é tão elevado. Também o erro associado á medida não ultrapassou 1,5cm, sendo considerado baixo. Na validade concorrente concluímos que é aos 0º que a metodologia se torna uma opção válida na aferição das distâncias medidas com uma boa a excelente concordância com o FOB. As medidas consideradas como opções válidas, nas diferentes amplitudes, podem funcionar como parâmetros clínicos de caracterização do posicionamento da omoplata, podendo vir a contribuir ainda para a caracterização da orientação da mesma.-------------------- ABSTRACT:Introduction: The kinematic relationship between the joints of the CAO has great importance in the function of MS, which is why more and more investigated and described. The positioning of the blade gets an important role in understanding the DCAO. There is no doubt the important role of the scapula in the dynamics of MS as well as the positioning of scapular dysfunction as a clinical parameter of the CAO. All these factors create the need to develop tools for evaluating the place of articulation ET. Most assessment tests, restrict its assessment to GU joint disorders, not incorporating a more dynamic and interactive way that respects the theoretical assumptions inherent in the REU. It is also important that the methods are easy to apply clinical and reliably to assess the validity and outcomes. Objectives: To contribute to the development of a methodology for evaluating the scapula in different ranges of MS, through the study of concurrent validity, reliability of intra-and inter-observer. Methodology: The sample consisted of 20 selected elements for convenience, between the body of students of IPS-ESS with no history of dysfunction of the CAO. We performed a kinematic analysis of each subject to MS, using a scanning device for electromagnetic analysis, the FOB. In each subject were also measured, the scapular distances under study, using tape measure. Each method of measuring the time consisted of two (test and retest), in each moment, the measures were collected by two different investigators. Results and Discussion: We considered as positive results that were above the threshold of 0.5, which ranks as a moderate to excellent correlation. The results show that the validity for the researcher in an action M1e M2 was only correlated with moderate to excellent values up to 30º of elevation of the MS. As for M3 only to 30º in the plane of the scapula has the same correlation values near the cutpoint. M4 has no value in correlation with the values of the FOB, and even negative correlation to 120 ° in the plane of the scapula. In M5 show only the values 0 ° correlational excellent to moderate. For investigator 2 in M1 and M2 will be like an investigator, there are only significant correlation values up to 30º of elevation of the MS. As for M3 all the values show excellent correlation to moderate with the exception of 120 ° in the frontal plane. In this researcher M4 has bad results. M5 already in the correlation values are moderate to 0º and 90 º. Regarding the results of ICC intra-observer, we can say that M5 was that these values come closest to the cut point. M1 and M2 are measures which are less than satisfactory results. At 60 ° there are more satisfactory values, followed by 0º and 30º, when we approached the highest levels, such as 90 ° and 120 °, these values tend to decrease. The inter-observer reliability for M1 only to 90 º and 120 ºcorrelation values were below the cutpoint. In M2, only 60 of the sagital plane did not have values above the cutpoint in M3 only 30º sagital plane did not obtain values above the cut-point, the same goes for M3 at 30 ° plane of the scapula and M5 at 30 º and 120 º in frontal plane. Conclusion: The results of this study indicate that the methodology in question has a high degree of inter-observer reliability, as far as intra-observer reliability is the degree of similarity is not as high. Also the error of measure did not exceed 1.5 cm, and is considered low. In concurrent validity conclude that it is at 0 ° the methodology becomes a valid option for the measurement of distances measured with a good to excellent agreement with the FOB. The measures considered as valid options in different amplitudes, can function as clinical parameters to characterize the positioning of the shoulder blade and could further contribute to the characterization of the orientation of the same.

Joining copper to stainless steel by friction stir diffusion process

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do Grau de Mestre em Engenharia Mecânica

The influence of brick residues in the behaviour of lime mortars

XXXVI IAHS World Congress on Housing - National Housing Programs-New Visions, November 03–07, 2008, Kolkata, India

Lime mortars with brick dust and grounded particles for ancient masonry: development and evaluation

HMC08 - 1st Historical Mortars Conference: Characterization, Diagnosis, Conservation, Repair and Compatibilit, LNEC, Lisbon, 24-26 September 2008

Range of motion measurements based on depth camera for clinical rehabilitation

Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica

Historic timber roof structures

Dissertação para obtenção do Grau de Mestre em Engenharia Civil – Estruturas e Geotecnia

Osteoclast activity in ankylosing spondylitis patients before and after TNF-blocking therapy

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease of the axial skeleton. The major outcome of this disease is defined by new bone formation, commonly observed in the ligaments of the intervertebral joints, that can lead to the formation of bony spurs, known as syndesmophytes. Previous studies have shown that serum levels of TNF, IL-6 and IL-17 are increased in AS patients and may be implicated in the development of secondary osteoporosis, since these cytokines are able to induce osteoclast (OC) differentiation and, therefore, bone resorption. In this work we aimed to assess the effects of TNF-blocking therapy in the systemic inflammatory environment of AS patients with active disease as well as in OC differentiation and activity. To accomplish this objective, we cultured circulating monocytes from AS patients, before and after therapy, under osteoclastogenic conditions and we performed two functional assays (TRAP staining and resorption pit assay) and analyzed the expression of osteoclast specific genes. We have shown that AS patients with active disease have increased levels of pro-inflammatory cytokines when compared with healthy subjects. We also found that IL-17, TGF-β and osteoprotegerin are decreased after TNF-blocking therapy. Interestingly, we also observed that after TNF-blocking therapy the expression of some genes is favoring osteoclastogenesis and that differentiated OCs have increased resorption activity. These results suggest that in active AS there may be an uncoupling between inflammation and OC activity that is reset by TNF-blocking therapy.

Gas tungsten arc welding of NiTi shape memory alloy

Shape memory alloys are characterized by the ability of recovering their initial shape after being deformed and by superelasticity. Since the discovery of these alloys, a new field of interest emerged not only for the scientific community but also to many industries. However, these alloys present poor machinability which constitute a constrain in the design of complex components for new applications. Thus, the demand for joining techniques able to join these alloys without compromising their properties became of great importance to enlarge the complexity of existing applications. Literature shows that these alloys are joined mainly using laser welding. In the present study, similar NiTi butt joints, were produced using TIG welding. The welds were performed in 1.5 mm thick plates across the rolling direction. A special fixture and gas assist device was designed and manufactured. Also a robot arm was adapted to accommodate the welding torch to assure the repeatability of the welding parameters. Welds were successfully achieved without macroscopic defects, such as pores and distortions. Very superficial oxidation was seen on the top surface due to insufficient shielding gas flow on the weld face. The welded joints were mechanically tested and structurally characterized. Testing methods were used to evaluate macro and microstructure, as well as the phase transformation temperatures, the mechanical single and cyclic behaviour and the shape recovery ability. Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), microhardness measurements were techniques also used to evaluate the welded joints. A depletion in Ni in the fusion zone was seen, as well as a shift in Ms temperature. For strain values of 4% the accumulated irrecoverable strain was of about 30% and increased with the strain imposed during cycling. Nevertheless, a complete recovery of initial shape was observed when testing the shape memory effect on a dedicated device that introduces a deformation of 6.7%. That is, the welding procedure does not remove the ability of the specimens to recover their initial shape.

Osteoclastogenesis, inflammatory cytokines and biomarkers of bone metabolism in psoriatic arthritis

RESUMO:A artrite psoriática (AP) é uma doença inflamatória crónica caracterizada por várias manifestações nas articulações, nas enteses e na pele. A formação de novo osso após inflamação nas enteses é um dos aspetos mais intrigantes desta doença. Os mecanismos celulares e moleculares deste processo ainda não são completamente conhecidos. Este estudo tem como objetivo compreender melhor os mecanismos subjacentes à formação e reabsorção óssea, bem como o efeito de anti-inflamatórios não esteroides (AINEs) nestes processos. Para atingir este objetivo foram quantificados biomarcadores do metabolismo ósseo e citocinas inflamatórias em doentes AP, antes e após terapêutica com AINEs. Os biomarcadores selecionados foram marcadores de remodelação óssea como CTX-I e P1NP, fatores de diferenciação e ativação de osteoclastos como o RANKL e a OPG, inibidores da via de sinalização Wnt, nomeadamente o DKK-1 e a SOST e ainda citocinas pro-inflamatórias como a IL-22 e a IL-23 e a prostaglandina PGE2. Neste contexto foram também estabelecidas culturas celulares de monócitos, isoladas de doentes AP e de controlos saudáveis. Os monócitos foram cultivados in vitro em condições não estimuladas e estimuladas e realizados dois ensaios funcionais: coloração com TRAP e ensaio de reabsorção. Foi observada uma diminuição nos níveis séricos de CTX-I e OPG em doentes AP em relação aos controlos. De igual forma os níveis séricos de SOST encontram-se significativamente mais baixos, em comparação com os controlos saudáveis. Estes valores de SOST são semelhantes aos dos doentes com espondilite anquilosante (EA), documentados anteriormente. Os ensaios com osteoclastos confirmaram a necessidade da presença de RANKL para estimulação da osteoclastogénese e que o celecoxib parece ter um papel inibitório neste processo. Os resultados obtidos sugerem que a população de doentes com AP analisados têm baixos níveis de reabsorção óssea e alguma atividade na formação óssea. --------------------------- ABSTRACT: Psoriatic arthritis (PsA) is a chronic inflammatory disease characterized by several manifestations involving the joints, enthesis and the skin. New bone formation after inflammation at enthesis site has been one of the most intriguing aspects of the disease. Cellular and molecular mechanisms in this process are still not completely understood. This study aims to understand better the mechanisms underlying bone formation and resorption and the effect of non-steroid anti-inflammatory drugs (NSAIDs) in these processes. To access that, biomarkers of bone metabolism and inflammatory cytokines were measured in PsA patients’ serum before and after NSAID therapy. These selected biomarkers were bone turnover markers such as CTX-I and P1NP, osteoclast differentiation and activation factors RANKL and OPG, Wnt pathway inhibitors DKK-1 and SOST and pro-inflammatory cytokines IL-22, IL-23 and prostaglandin PGE2. In this context monocyte cell culture was also established after PBMC isolation from PsA patients and healthy controls. Monocytes were cultured in vitro under unstimulated and stimulated conditions and two functional assays were performed: TRAP staining and resorption pit assay. It was demonstrated that CTX-I and OPG serum levels in PsA patients were lower than controls. SOST levels were extremely decreased in comparison with controls, resembling the ankylosing spondylitis patients results already documented. Osteoclast assays confirmed the need of RANKL in stimulating osteoclastogenesis and that celecoxib seems to have an inhibitor role in this process. The results obtained suggest that PsA patient population analyzed in this study have low bone resorption levels and some bone formation activity.

Novel antibiotic-loaded orthopaedic bone cements: insights on drug release profiles and biocompatibility

Acrylic bone cement (BC) is widely used as an anchor of artificial joints. Bacterial infection due to biofilm formation and inflammation are common and difficult to treat problems associated with commercial available BC formulations. Research on novel BC compositions is urgently needed. The main objective of this thesis was to develop a new biocompatible antibiotic-loaded BC with improved release profile. To achieve that aim several additives were incorporated, as an antibiotic (levofloxacin) to combat bacterial growth, an anti-inflammatory drug (diclofenac) to decrease the inflammatory process and two well-known and broadly used biopolymers, alginate and chitosan in order to increase matrix porosity, and in this way to intensify the amount of released drug. Novel BC formulations were tested in order to find the most suitable one that had potential to proceed to clinical application. Numerous tests were conducted as: a) evaluation of drug release profiles in different biomimetic media, b) mechanical and surface studies, c) microbiological activity testing against Staphylococcus aureus and d) in vitro biocompatibility assays (fibroblasts and osteoblasts). In general, the addition of biopolymers increased drug release, didn’t compromised BC mechanical properties and increased BC hydrophilicity. Microbiological testing revealed that Lev[BC]Chi was the only matrix that reduced significantly biofilm formation. On the contrary, alginate and diclofenac loading into BC seemed to increase biofilm growth. Biocompatibility studies showed some decrease in cell viability, in particularly on osteoblasts, mainly due to the high amounts of released drugs. In conclusion, the present work has shown that the matrix with more potential to proceed in further investigations was Lev[BC]Chi. Other conditions (namely additives and drugs concentrations) should be evaluated with the other tested BC matrices before being discharged.