Ligantes de baixo impacto ambiental e baixo custo, baseados na ativação química de escórias de aciaria

Dissertação de mestrado integrado em Engenharia Civil

Desenvolvimento e validação de uma solução construtiva em BTC

Dissertação de mestrado integrado em Engenharia Civil

Fundamental studies on natural deep eutectic solvents: physico-chemical, thermal and rheological properties

When combined at particular molar fractions, sugars, aminoacids or organic acids a present a high melting point depression, becoming liquids at room temperature. These are called Natural Deep Eutectic Solvents – NADES and are envisaged to play a major role on the chemical engineering processes of the future. Nonetheless, there is a significant lack of knowledge of its fundamental and basic properties, which is hindering their industrial applications. For this reason it is important to extend the knowledge on these systems, boosting their application development [1]. In this work, we have developed and characterized NADES based on choline chloride, organic acids, amino acids and sugars. Their density, thermal behavior, conductivity and polarity were assessed for different compositions. The conductivity was measured from 0 to 40 °C and the temperature effect was well described by the Vogel-Fulcher-Tammann equation. The morphological characterization of the crystallizable materials was done by polarized optical microscopy that provided also evidence of homogeneity/phase separation. Additionally, the rheological and thermodynamic properties of the NADES and the effect of water content were also studied. The results show these systems have Newtonian behavior and present significant viscosity decrease with temperature and water content, due to increase on the molecular mobility. The anhydrous systems present viscosities that range from higher than 1000Pa.s at 20°C to less than 1Pa.s at 70°C. DSC characterization confirms that for water content as high as 1:1:1 molar ratio, the mixture retains its single phase behavior. The results obtained demonstrate that the NADES properties can be finely tunned by careful selection of its constituents. NADES present the necessary properties for use as extraction solvents. They can be prepared from inexpensive raw materials and tailored for the selective extraction of target molecules. The data produced in this work is hereafter importance for the selection of the most promising candidates avoiding a time consuming and expensive trial and error phase providing also data for the development of models able to predict their properties and the mechanisms that allow the formation of the deep eutectic mixtures.

Production and characterization of ZrCN-Ag coatings deposited by mganetron sputtering

Tese de Doutoramento (Programa doutoral em Engenharia de Materiais)

Effects of protein-calorie restriction on mechanical function of hypertrophied cardiac muscle

OBJECTIVE: To assess the effect of food restriction (FR) on hypertrophied cardiac muscle in spontaneously hypertensive rats (SHR). METHODS: Isolated papillary muscle preparations of the left ventricle (LV) of 60-day-old SHR and of normotensive Wistar-Kyoto (WKY) rats were studied. The rats were fed either an unrestricted diet or FR diet (50% of the intake of the control diet) for 30 days. The mechanical function of the muscles was evaluated through monitoring isometric and isotonic contractions. RESULTS: FR caused: 1) reduction in the body weight and LV weight of SHR and WKY rats; 2) increase in the time to peak shortening and the time to peak developed tension (DT) in the hypertrophied myocardium of the SHR; 3) diverging changes in the mechanical function of the normal cardiac muscles of WKY rats with reduction in maximum velocity of isotonic shortening and of the time for DT to decrease 50% of its maximum value, and increase of the resting tension and of the rate of tension decline. CONCLUSION: Short-term FR causes prolongation of the contraction time of hypertrophied muscles and paradoxal changes in mechanical performance of normal cardiac fibers, with worsening of the shortening indices and of the resting tension, and improvement of the isometric relaxation.

Técnicas de análise laboratorial para solos, matéria vegetal e corretivos orgãnicos

Dissertação de mestrado em Técnicas de Caracterização e Análise Química

Gestão integrada dos recursos hídricos da região de Fafe: caracterização da qualidade das águas superficiais, potencial hidrogeológico das rochas fraturadas

Dissertação de mestrado em Geociências (área de especialização em Recursos Geológicos)

Chemical functionalization in bionanoparticles

Dissertação de mestrado em Biofísica e Bionanossistemas

Clinical significance of in-hospital reocclusion after mechanical reperfusion and percutaneous transluminal coronary angioplasty for acute myocardial infarction

OBJECTIVE: To analyze the effects of in-hospital reocclusion of reperfused AMI culprit coronary arteries in mortality and to identify the predictors. METHODS: The present study comprises a sample of 155 patients with AMI who underwent successful mechanical reperfusion by direct coronary angioplasty and angiographic control during hospitalization or before discharge. Patients were classified into group A: reoccluded patients (n=30) and group B: non-reoccluded patients (n=125). RESULTS: We identified in-hospital reocclusion predictors and found a greater significance in mortality among reoccluded patients (23,3% x 1.6%; p=0.00004). Silent reocclusion or typical angina at reocclusion had a good prognosis. The independent predictors of in-hospital mortality were hypertension, multiarterial lesions, totally occluded AMI culprit lesions, failed redilatation, failed redilatation in comparison with no intention to redilate, no redilatation in comparison with no atempt to redilate, and reocclusion within the first 48 to 72 hours. The decision to redilate, independently of the result, led to a 50.0% reduction in hospital mortality (p=0.0366). CONCLUSION: In-hospital AMI culprit coronary artery reocclusion had an adverse effect similar to that reported in clinical studies with high mortality rates (23.3% x 1.6%; p=0.00004). The major contribution of this study is to recommend the reopening of reoccluded AMI culprit coronary arteries as a means for the management of coronary artery reocclusion.

Sensitive label-free electron chemical capacitive transducer signal for D-dimer electroanalyses

Supplementary data associated with this article can be found, in the online version, at: http://dx.doi.org/10.1016/j.electacta.2015.09.169.

Desenvolvimento de membranas poliméricas baseadas em Poli(fluoreto de vinilideno) para a filtração de materiais biológicos

Dissertação de mestrado em Biofísica e Bionanossistemas

Beeswax organogels: Influence of gelator concentration and oil type in the gelation process

This work focused on how different types of oil phase, MCT (medium chain triglycerides) and LCT (long chain triglycerides), exert influence on the gelation process of beeswax and thus properties of the organogel produced thereof. Organogels were produced at different temperatures and qualitative phase diagrams were constructed to identify and classify the type of structure formed at various compositions. The microstructure of gelator crystals was studied by polarized light microscopy. Melting and crystallization were characterized by differential scanning calorimetry and rheology (flow and small amplitude oscillatory measurements) to understand organogels' behaviour under different mechanical and thermal conditions. FTIR analysis was employed for a further understanding of oil-gelator chemical interactions. Results showed that the increase of beeswax concentration led to higher values of storage and loss moduli (G, G) and complex modulus (G*) of organogels, which is associated to the strong network formed between the crystalline gelator structure and the oil phase. Crystallization occurred in two steps (well evidenced for higher concentrations of gelator) during temperature decreasing. Thermal analysis showed the occurrence of hysteresis between melting and crystallization. Small angle X-ray scattering (SAXS) analysis allowed a better understanding in terms of how crystal conformations were disposed for each type of organogel. The structuring process supported by medium or long-chain triglycerides oils was an important exploit to apprehend the impact of different carbon chain-size on the gelation process and on gels' properties.

Percutaneous mechanical mitral commissurotomy performed with a Cribier's metallic valvulotome. Initial results

OBJECTIVE: To evaluate the immediate results of percutaneous mechanical mitral commissurotomy. METHODS: Thirty patients underwent percutaneous mechanical mitral commissurotomy performed with a Cribier's metallic valvulotome from 8/11/99 to 2/4/00. Mean age was 30.7 years, and 73.3% were women. With regards to functional class, 63.3% were class III, and 36.7% were class IV. The echocardiographic score had a mean value of 7.5± 1.8. RESULTS: The mitral valve area increased from 0.97±0.15cm² to 2.16±0.50cm² (p>0.0001). The mean diastolic gradient decreased from 17.9±5.0mmHg to 3.2±1.4mmHg. The mean left atrial pressure decreased from 23.6±5.4mmHg to 8.6±3.1mmHg, (p>0.0001). Systolic pressure in the pulmonary artery decreased from 52.7±18.3mmHg to 32.2±7.4mmHg. Twenty-nine cases were successful. One patient developed severe mitral regurgitation. Interatrial septal defect was observed and one patient. One patient had cardiac tamponade due to left ventricular perforation. No deaths occurred. CONCLUSION: This method has proven to be safe and efficient in the treatment of rheumatic mitral stenosis. The potential advantage is that it can be used multiple times after sterilization, which decreases procedural costs significantly.

Mechanical versus biological aortic valve implants in the elderly. A comparison of early and mid-term results

OBJECTIVE: Our aim was to compare, in a non randomized study, the surgical outcome in elderly patients with mechanical (Group 1; n=83) and bioprosthetic valve implants (Group 2; n=136). METHODS: During a three year period, 219 patients >75 years underwent Aortic Valve Replacement. The groups matched according to age, sex, comorbidity, valve pathology and concomitant Coronary Artery Bypass Surgery. Follow-up was a total of 469 patient-years (mean follow-up 2.1 years, maximum 4,4 years). RESULTS: Operative mortality was zero and the overall early mortality was 2.3 % (within 30 days). Actuarial survival was 87.5 ± 4.0% and 66.1 ± 7.7% (NS) at 4 years in Group 1 and Group 2, respectively. Freedom from valve-related death was 88.9 ± 3.8% in Group 1 and 69.9±7.9% (NS) in Group 2 at 4 years. CONCLUSION: Aortic Valve Replacement in the elderly (>75 years) is a safe procedure even in cases where concomitant coronary artery revascularization is performed. Only a few anticoagulant-related complications were reported and this may indicate that selected groups of elderly patients with significant life expectancy may benefit from mechanical implants .

Antibacterial properties of multifunctional coatings Ag-ZrCN for biomedical devices: a novel approach

PhD in Sciences Specialty in Physics