976 resultados para Pressure method
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Tese apresentada como requisito parcial para obtenção do grau de Doutor em Gestão de Informação
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We compare the performance of Cape Verde and Mozambique concerning financial credibility as measured by Exchange Market Pressure, an institutional feature that has often been overlooked in the literature as a relevant institution for economies. Drawing on previous research by Macedo et al. (2009), we expand their analysis and, using several definitions of “financial credibility”, all related to different angles on Exchange Market Pressure indices, we conclude that - against reasonable benchmarks in their respective regions - financial credibility has been very good for Cape Verde and fairly good for Mozambique.
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Dissertação para obtenção do Grau de Doutor em Química Sustentável
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Dissertation presented to obtain the Ph.D degree in Chemistry.
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Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica
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Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica
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Dissertação para obtenção do grau de Mestre em Engenharia Química e Bioquímica
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Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica
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Dissertação para obtenção do Grau de Mestre em Engenharia Geológica (Georrecursos)
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Due to the importance and wide applications of the DNA analysis, there is a need to make genetic analysis more available and more affordable. As such, the aim of this PhD thesis is to optimize a colorimetric DNA biosensor based on gold nanoprobes developed in CEMOP by reducing its price and the needed volume of solution without compromising the device sensitivity and reliability, towards the point of care use. Firstly, the price of the biosensor was decreased by replacing the silicon photodetector by a low cost, solution processed TiO2 photodetector. To further reduce the photodetector price, a novel fabrication method was developed: a cost-effective inkjet printing technology that enabled to increase TiO2 surface area. Secondly, the DNA biosensor was optimized by means of microfluidics that offer advantages of miniaturization, much lower sample/reagents consumption, enhanced system performance and functionality by integrating different components. In the developed microfluidic platform, the optical path length was extended by detecting along the channel and the light was transmitted by optical fibres enabling to guide the light very close to the analysed solution. Microfluidic chip of high aspect ratio (~13), smooth and nearly vertical sidewalls was fabricated in PDMS using a SU-8 mould for patterning. The platform coupled to the gold nanoprobe assay enabled detection of Mycobacterium tuberculosis using 3 8l on DNA solution, i.e. 20 times less than in the previous state-of-the-art. Subsequently, the bio-microfluidic platform was optimized in terms of cost, electrical signal processing and sensitivity to colour variation, yielding 160% improvement of colorimetric AuNPs analysis. Planar microlenses were incorporated to converge light into the sample and then to the output fibre core increasing 6 times the signal-to-losses ratio. The optimized platform enabled detection of single nucleotide polymorphism related with obesity risk (FTO) using target DNA concentration below the limit of detection of the conventionally used microplate reader (i.e. 15 ng/μl) with 10 times lower solution volume (3 μl). The combination of the unique optical properties of gold nanoprobes with microfluidic platform resulted in sensitive and accurate sensor for single nucleotide polymorphism detection operating using small volumes of solutions and without the need for substrate functionalization or sophisticated instrumentation. Simultaneously, to enable on chip reagents mixing, a PDMS micromixer was developed and optimized for the highest efficiency, low pressure drop and short mixing length. The optimized device shows 80% of mixing efficiency at Re = 0.1 in 2.5 mm long mixer with the pressure drop of 6 Pa, satisfying requirements for the application in the microfluidic platform for DNA analysis.
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In this work, a volumetric unit previously assembled by the research group was upgraded. This unit revamping was necessary due to the malfunction of the solenoid valves employed in the original experimental setup, which were not sealing the gas properly leading to erroneous adsorption equilibrium measurements. Therefore, the solenoid valves were substituted by manual ball valves. After the volumetric unit improvement its operation was validated. For this purpose, the adsorption equilibrium of carbon dioxide (CO2) at 323K and 0 - 20 bar was measured on two different activated carbon samples, in the of extrudates (ANG6) and of a honeycomb monolith (ACHM). The adsorption equilibrium results were compared with data previously measured by the research group, using a high-pressure microbalance from Rubotherm GmbH (Germany) – gravimetric. The results obtained using both apparatuses are coincident thus validating the good operation of the volumetric unit upgraded in this work. Furthermore, the adsorption equilibrium of CO2 at 303K and 0 - 10 bar on Metal-Organic Frameworks (MOFs) Cu-BTC and Fe-BTC was also studied. The CO2 adsorption equilibrium results for both MOFs were compared with the literature results showing good agreement, which confirms the good quality of the experimental results obtained in the new volumetric unit. Cu-BTC sample showed significantly higher CO2 adsorption capacity when compared with the Fe-BTC sample. The revamping of the volumetric unit included a new valve configuration in order to allow testing an alternative method for the measurement of adsorption equilibrium. This new method was employed to measure the adsorption equilibrium of CO2 on ANG6 and ACHM at 303, 323 and 353K within 0-10 bar. The good quality of the obtained experimental data was testified by comparison with data previously obtained by the research group in a gravimetric apparatus.
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This work is divided into two distinct parts. The first part consists of the study of the metal organic framework UiO-66Zr, where the aim was to determine the force field that best describes the adsorption equilibrium properties of two different gases, methane and carbon dioxide. The other part of the work focuses on the study of the single wall carbon nanotube topology for ethane adsorption; the aim was to simplify as much as possible the solid-fluid force field model to increase the computational efficiency of the Monte Carlo simulations. The choice of both adsorbents relies on their potential use in adsorption processes, such as the capture and storage of carbon dioxide, natural gas storage, separation of components of biogas, and olefin/paraffin separations. The adsorption studies on the two porous materials were performed by molecular simulation using the grand canonical Monte Carlo (μ,V,T) method, over the temperature range of 298-343 K and pressure range 0.06-70 bar. The calibration curves of pressure and density as a function of chemical potential and temperature for the three adsorbates under study, were obtained Monte Carlo simulation in the canonical ensemble (N,V,T); polynomial fit and interpolation of the obtained data allowed to determine the pressure and gas density at any chemical potential. The adsorption equilibria of methane and carbon dioxide in UiO-66Zr were simulated and compared with the experimental data obtained by Jasmina H. Cavka et al. The results show that the best force field for both gases is a chargeless united-atom force field based on the TraPPE model. Using this validated force field it was possible to estimate the isosteric heats of adsorption and the Henry constants. In the Grand-Canonical Monte Carlo simulations of carbon nanotubes, we conclude that the fastest type of run is obtained with a force field that approximates the nanotube as a smooth cylinder; this approximation gives execution times that are 1.6 times faster than the typical atomistic runs.
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In this study, the larvicidal activity of dried leaf extracts from Pinus caribaea Morelet against Aedes aegypti was evaluated for the first time. Pinus caribaea extracts were obtained by macerating dried leaves in alkaline hydroethanol, ethanol and acetone solutions followed by evaporation under reduced pressure. The lignin content was quantified using the thioglycolic acid complexation method. Lethality bioassays (LC50 and LC90) were carried out in accordance with the recommendations of the World Health Organization. The results showed that the acetone extract from Pinus caribaea was more active, and that larvicidal activity was associated with lignin concentration.
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Rupture of aortic aneurysms (AA) is a major cause of death in the Western world. Currently, clinical decision upon surgical intervention is based on the diameter of the aneurysm. However, this method is not fully adequate. Noninvasive assessment of the elastic properties of the arterial wall can be a better predictor for AA growth and rupture risk. The purpose of this study is to estimate mechanical properties of the aortic wall using in vitro inflation testing and 2D ultrasound (US) elastography, and investigate the performance of the proposed methodology for physiological conditions. Two different inflation experiments were performed on twelve porcine aortas: 1) a static experiment for a large pressure range (0 – 140 mmHg); 2) a dynamic experiment closely mimicking the in vivo hemodynamics at physiological pressures (70 – 130 mmHg). 2D raw radiofrequency (RF) US datasets were acquired for one longitudinal and two cross-sectional imaging planes, for both experiments. The RF-data were manually segmented and a 2D vessel wall displacement tracking algorithm was applied to obtain the aortic diameter–time behavior. The shear modulus G was estimated assuming a Neo-Hookean material model. In addition, an incremental study based on the static data was performed to: 1) investigate the changes in G for increasing mean arterial pressure (MAP), for a certain pressure difference (30, 40, 50 and 60 mmHg); 2) compare the results with those from the dynamic experiment, for the same pressure range. The resulting shear modulus G was 94 ± 16 kPa for the static experiment, which is in agreement with literature. A linear dependency on MAP was found for G, yet the effect of the pressure difference was negligible. The dynamic data revealed a G of 250 ± 20 kPa. For the same pressure range, the incremental shear modulus (Ginc) was 240 ± 39 kPa, which is in agreement with the former. In general, for all experiments, no significant differences in the values of G were found between different image planes. This study shows that 2D US elastography of aortas during inflation testing is feasible under controlled and physiological circumstances. In future studies, the in vivo, dynamic experiment should be repeated for a range of MAPs and pathological vessels should be examined. Furthermore, the use of more complex material models needs to be considered to describe the non-linear behavior of the vascular tissue.
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RESUMO - Prestar cuidados a um doente que além da patologia de base apresenta úlceras por pressão (UPP) implica um esforço acrescido por parte da Instituição de saúde e equipa multidisciplinar, custos acrescidos no tratamento e reactualizações frequentes, para que se prestem cuidados que primem pela excelência. OBJETIVOS: caracterizar o impacto clinico e económico das UPP e relacioná-los com as temáticas da Segurança do Doente e Qualidade em Saúde. METODOLOGIA: estudo observacional retrospetivo longitudinal, com uma população do estudo constituída por 164 adultos que estiveram internados entre 1 de janeiro a 31 de dezembro de 2012 no CHMT e que desenvolveram UPP durante o internamento. RESULTADOS: com uma população do estudo maioritariamente masculina (57,3%), e uma média de idades de 81 anos, a taxa de incidência de UPP foi de 1,4%. A maior parte de UPP desenvolvidas durante o internamento foram as de categoria II e a localização anatómica mais frequente os membros inferiores. Em termos de impacto económico, 842.609 euros foi o montante estimado correspondente aos custos totais associados às UPP. CONCLUSÃO: o contínuo investimento na Segurança do Doente e na Qualidade em Saúde e, em especial, na prevenção das UPP devem ser mantidos para que se continuem a mobilizar esforços que minimizem a frequência da ocorrência das últimas. Mais do que tratar pretende-se prevenir tendo em conta que as consequências, quer para a díade doente-família como para as Instituições de saúde, são significativas.