48 resultados para potential curves


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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

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Dissertation presented to obtain the Ph.D degree in Biochemistry

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RESUMO: A surdez súbita (SS) caracteriza-se por uma perda abrupta de audição, mais frequentemente unilateral e associada a sensação de preenchimento aural, acufenos e vertigem. Afecta 5-20/100.000pessoas/ano (sobretudo adultos em fase activa na década de 40), com grande impacto na qualidade de vida. Possíveis causas incluem doenças infecciosas, circulatórias, traumáticas, imunológicas, neoplásicas, neurológicas, tóxicas e cocleares. No entanto, a causa da SS permanece desconhecida na maioria dos casos (80%), o que origina tratamentos controversos e frequentemente ineficientes. Os tratamentos disponíveis variam desde corticosteróides a antivirais, vasodilatadores, anti-agregantes, anticoagulantes, vitaminas e oxigénio hiperbárico (OHB). Atendendo a falta de informação relativa à etiologia e fisiopatologia da SS, pretendemos avaliar a evolução clínica dos doentes com SS tratados com OHB no Centro de Medicina Subaquática e Hiperbárica (CMSH) de Lisboa entre 2000 e 2005, durante um período mínimo de 5 anos, na tentativa de identificar eventuais factores de risco ou noxas clínicas com a SS. O estudo retrospectivo proposto baseia-se na revisão de processos clínicos do CMSH e na aplicação telefónica de questionários médicos de “follow-up” confidenciais – tanto a doentes (grupo de estudo), como aos respectivos esposos/companheiros/membros próximos da família (grupo de controlo) –, com particular ênfase nos antecedentes médicos e história clínica actual. Um estudo preliminar de 20 pessoas (10 doentes e 10 controlos) foi efectuado para antecipar dificuldades e estimar as necessidades logísticas. As dificuldades identificadas foram: 1) selecção dos doentes com números de telefone válidos e processos clínicos completos (com audiograma inicial e final); 2) contacto telefónico com os participantes de ambos os grupos (de estudo e controlo); 3) recursos humanos requeridos. Dado que a SS não é uma doença em si, mas um sintoma de uma doença subjacente, acreditamos que este estudo epidemiológico seja importante e útil, capaz de gerar novas luzes sobre a fisiopatologia e mecanismos desta entidade clínica.-------------ABSTRACT:Sudden sensorineural hearing loss (SSHL) is characterized by abrupt, mostly unilateral loss of hearing, frequently associated to aural fullness, tinnitus and vertigo. It affects 5-20/100.000 people/year (particularly working adults in the 40ths), with huge impact on quality of life. Possible causes include infectious, circulatory, traumatic, immunologic, metabolic, neoplastic, neurologic, toxic and unidentified cochlear diseases. Nevertheless, SSHL’s etiology remains unknown in most cases (80%), giving rise to controversial (and frequently ineffective) treatments. Available therapies range from corticosteroids to antivirals, vasodilators, antiaggregants, anticoagulants, vitamins and hyperbaric oxygen (HBO). Given the lack of data concerning SSHL’s etiology and physiopathology, we intend to evaluate clinical evolution of such patients treated with HBO in the Underwater and Hyperbaric Medical Center (UHMC) at Lisbon from 2000 to 2005 during a minimum period of 5 years, in an attempt to identify eventual risk factors or clinical associations to SSHL. The intended retrospective study is based on the review of patients’ medical charts from UHMC and confidential follow-up questionnaires applied telephonically both to patients (study group) and patients’ spouse/partner/close family member (control group), focusing past and present medical history. A preliminary study of 20 subjects (10 of each group) was performed to anticipate difficulties and to estimate the required logistics. The identified difficulties were: 1) selection of subjects with valid phone numbers and complete medical charts (with initial and final audiograms); 2) telephonic contact with subjects from the study and control group; 3) human logistics required. As it is believed that SSHL is not a disease by itself but rather a symptom of an underlying disease, we believe that this epidemiologic study is important and will hopefully generate sound scientific knowledge concerning physiopathology and mechanism of disease of SSHL.

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Dissertation to obtain master degree in Biotechnology

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Dissertation to obtain a Master Degree in Molecular Genetics and Biomedicine

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Dissertação para obtenção do Grau de Mestre em Energias Renováveis – Conversão Eléctrica e Utilização Sustentável

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Dissertation toobtaina Master of Science degree in Bioorganics

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Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente, perfil de Ordenamento do Território e Impactes Ambientais

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Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente – Perfil Gestão e Sistemas Ambientais

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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

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Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente, perfil Gestão e Sistemas Ambientais

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Dissertação para obtenção do Grau de Mestre em Engenharia Geológica (Georrecursos)

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(Poly)phenols are the most widely distributed secondary metabolites, in plants, and, therefore, are regular constituents of human food products. The regular ingestion of (poly)phenol-containing foods has been associated with a reduced risk of acquiring chronic diseases and many studies are currently trying to corroborate this theory. However, the precise contribution of (poly)phenols to disease prevention is still unknown.(...)

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The main objective of this thesis is to study the developing fields of aquaponics and its potential for aquaculture wastewater treatment and human urine treatment. Aquaponics is a food production system which combines fish farming (aquaculture) with soilless crop farming (hydroponics). In this thesis the concept of aquaponics and the underlying processes are explained. Research on aquaculture wastewater and human urine wastewater is reviewed and its potential application with aquaponic systems is studied. An overview of the different types of aquaponic systems and current research on the field is also presented. A case study was conducted in a farm in Askeröd, Sweden, which involved building two aquaponic systems (System 1 and System 2) and a human urine-based aquaponic system (System 3), with different degrees of component complexity and sizes. The design, building and monitoring of System 1, System 2 and System 3 was documented and described in detail. Four day experiments were conducted which tested the evolution in concentration of Total Ammonia Nitrogen (NH4+/NH3), Nitrite (NO2-), Nitrate (NO3-), Phosphate (PO43-), and Dissolved Oxygen (O2) after an initial nutrient input. The goal was to assess the concentrations of these parameters after four days and compare them with relevant literature examples in the aquaculture industry and in source-separated urine research. Neither of the two aquaponic systems (System 1 and System 2) displayed all of the parameter concentrations in the last day of testing below reference values found in literature. The best performing of the aquaponic systems was the more complex system (System 2) combining the hydroponic Nutrient Film Technique with a Deep Water Culture component, with a Total Ammonia Nitrogen concentration of 0,20 mg/L, a Nitrite concentration of 0,05 mg/L, a Nitrate concentration of 1,00-5,00 mg/L, a Phosphate concentration of <0,02 mg/L and a Dissolved Oxygen concentration of 8,00 mg/L. The human urine-based aquaponic system (System 3) underperformed in achieving the reference concentration values in literature for most parameters. The removal percentage between the higher recorded values after the input addition and the final day of testing was calculated for two literature examples of separated urine treatment and System 3. The system had a removal percentage of 75% for Total Ammonia Nitrogen, 98% for Nitrite, 25% for Nitrate and 50% for Phosphate. These percentages still underperformed literature examples in most of the tested parameters. The results gathered allowed to conclude that while aquaculture wastewater treatment and human urine treatment is possible with aquaponics systems, overall these did not perform as well as some examples found in recirculating aquaculture systems and source-separated urine treatment literature. However, better measuring techniques, longer testing periods and more research is recommended in this field in order to draw an improved representative conclusion.

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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.