Modela����o estat��stica das co-infec����es da SIDA em pa��ses da Uni��o Europeia

Disserta����o apresentada para obten����o do Grau de Doutor em Matem��tica, especialidade de Estat��stica, pela Universidade Nova de Lisboa, Faculdade de Ci��ncias e Tecnologia

Estrat��gias de alimenta����o para a optimiza����o do processo de produ����o de PHAs por via bacteriana

Disserta����o apresentada na Faculdade de Ci��ncias e Tecnologia da Universidade Nova de Lisboa para obten����o do grau de Mestre em Engenharia Qu��mica e Bioqu��mica

An��lise cr��tica do programa da reforma educativa para o ensino do portugu��s LS na 7�� classe em Angola

Disserta����o para a obten����o de grau de Mestre em Ensino de Portugu��s Como L��ngua Segunda/ L��ngua Estrangeira

Medir a qualidade do com��rcio eletr��nico. Uma aplica����o ao e-Retalho em Portugal.

Disserta����o apresentada como requisito parcial para obten����o do grau de Mestre em Estat��stica e Gest��o de Informa����o

Partial Least Square ��� Path Modeling: metodologia, software e aplica����o

Trabalho de Projeto apresentado como requisito parcial para obten����o do grau de Mestre em Estat��stica e Gest��o de Informa����o

Green IT adoption via virtualization

Disserta����o apresentada como requisito parcial para obten����o do grau de Mestre em Estat��stica e Gest��o de Informa����o

Determinantes da satisfa����o dos estudantes de primeiro ciclo de estudos na Universidade Nova de Lisboa

Trabalho de Projeto apresentado como requisito parcial para obten����o do grau de Mestre em Estat��stica e Gest��o de Informa����o

A satisfa����o dos alunos do ensino superior: o caso do ISEGI-NOVA

Disserta����o apresentada como requisito parcial para obten����o do grau de Mestre em Estat��stica e Gest��o de Informa����o

Controlo de reac����es de polimeriza����o em miniemuls��o atrav��s de t��cnicas de espectroscopia NIR e Raman

Disserta����o para obten����o do Grau de Mestre em Engenharia Qu��mica e Bioqu��mica

Monitoring and modelling of membrane bioreactors for wastewater treatment incorporating 2D fluorescence spectroscopy

Disserta����o para obten����o do Grau de Doutor em Engenharia Qu��mica e Bioqu��mica, Especialidade em Engenharia Bioqu��mica

Desenvolvimento de m��todos de espetroscopia NIR. Quantifica����o de grupos hidr��xilo em pol��meros

O objetivo deste estudo �� o desenvolvimento e valida����o de m��todos espectrosc��picos (espectroscopia NIR) que possam vir a substituir os m��todos qu��micos convencionais, para quantifica����o de grupos hidr��xilo em resinas alqu��dicas. As resinas alqu��dicas estudadas neste trabalho s��o normalmente utilizadas em sistemas de revestimento de dois componentes, em que os seus grupos hidr��xilo reagem com pr��-pol��meros de isocianato para formar revestimentos de alta dureza. Por este motivo e por quest��es processuais ligadas �� estequiometria da rea����o existente na aplica����o referida, �� extremamente importante a quantifica����o destes grupos. O m��todo mais comum de quantifica����o de grupos hidr��xilo �� conhecido como m��todo de titula����o. Este �� um m��todo demorado, pois cada medi����o implica um procedimento experimental de cerca de duas horas, para al��m de ser muito dispendioso, a n��vel econ��mico. Foram estudadas as influ��ncias da temperatura, heterogeneidade e n��vel de enchimento da c��lula na recolha do espectro. As conclus��es dos estudos mencionados levaram �� fixa����o de um tempo ideal de perman��ncia da c��lula dentro da c��mara do espectrofot��metro antes da medi����o do espectro. Para al��m disto, conclui-se que para lotes standard, a heterogeneidade n��o �� uma vari��vel significativa. O n��vel da c��lula deve ser mantido constante. Os m��todos desenvolvidos, baseados na norma de qualidade ISO 15063:2011, foram constru��dos a partir de algoritmos de Partial Least Squares Regression (PLS), utilizando um equipamento NIRVIS, B��chi��. Foram obtidos bons coeficientes de regress��o linear para a Resina A (R2>0,9). Quanto aos restantes resultados, estes indicam a possibilidade de aplica����o em resinas do mesmo tipo. Este m��todo proporciona resultados 8 vezes mais r��pidos e com custos em material que representam 1% do m��todo standard.

Desenvolvimento de m��todos de espetroscopia NIR. Quantifica����o de grupos hidr��xilo em pol��meros

O objetivo deste estudo �� o desenvolvimento e valida����o de m��todos espectrosc��picos (espectroscopia NIR) que possam vir a substituir os m��todos qu��micos convencionais, para quantifica����o de grupos hidr��xilo em resinas alqu��dicas. As resinas alqu��dicas estudadas neste trabalho s��o normalmente utilizadas em sistemas de revestimento de dois componentes, em que os seus grupos hidr��xilo reagem com pr��-pol��meros de isocianato para formar revestimentos de alta dureza. Por este motivo e por quest��es processuais ligadas �� estequiometria da rea����o existente na aplica����o referida, �� extremamente importante a quantifica����o destes grupos. O m��todo mais comum de quantifica����o de grupos hidr��xilo �� conhecido como m��todo de titula����o. Este �� um m��todo demorado, pois cada medi����o implica um procedimento experimental de cerca de duas horas, para al��m de ser muito dispendioso, a n��vel econ��mico. Foram estudadas as influ��ncias da temperatura, heterogeneidade e n��vel de enchimento da c��lula na recolha do espectro. As conclus��es dos estudos mencionados levaram �� fixa����o de um tempo ideal de perman��ncia da c��lula dentro da c��mara do espectrofot��metro antes da medi����o do espectro. Para al��m disto, conclui-se que para lotes standard, a heterogeneidade n��o �� uma vari��vel significativa. O n��vel da c��lula deve ser mantido constante. Os m��todos desenvolvidos, baseados na norma de qualidade ISO 15063:2011, foram constru��dos a partir de algoritmos de Partial Least Squares Regression (PLS), utilizando um equipamento NIRVIS, B��chi��. Foram obtidos bons coeficientes de regress��o linear para a Resina A (R2>0,9). Quanto aos restantes resultados, estes indicam a possibilidade de aplica����o em resinas do mesmo tipo. Este m��todo proporciona resultados 8 vezes mais r��pidos e com custos em material que representam 1% do m��todo standard.

Experimental and modeling studies on reverse electrodialysis for sustainable power generation

A potentially renewable and sustainable source of energy is the chemical energy associated with solvation of salts. Mixing of two aqueous streams with different saline concentrations is spontaneous and releases energy. The global theoretically obtainable power from salinity gradient energy due to World���s rivers discharge into the oceans has been estimated to be within the range of 1.4-2.6 TW. Reverse electrodialysis (RED) is one of the emerging, membrane-based, technologies for harvesting the salinity gradient energy. A common RED stack is composed by alternately-arranged cation- and anion-exchange membranes, stacked between two electrodes. The compartments between the membranes are alternately fed with concentrated (e.g., sea water) and dilute (e.g., river water) saline solutions. Migration of the respective counter-ions through the membranes leads to ionic current between the electrodes, where an appropriate redox pair converts the chemical salinity gradient energy into electrical energy. Given the importance of the need for new sources of energy for power generation, the present study aims at better understanding and solving current challenges, associated with the RED stack design, fluid dynamics, ionic mass transfer and long-term RED stack performance with natural saline solutions as feedwaters. Chronopotentiometry was used to determinate diffusion boundary layer (DBL) thickness from diffusion relaxation data and the flow entrance effects on mass transfer were found to avail a power generation increase in RED stacks. Increasing the linear flow velocity also leads to a decrease of DBL thickness but on the cost of a higher pressure drop. Pressure drop inside RED stacks was successfully simulated by the developed mathematical model, in which contribution of several pressure drops, that until now have not been considered, was included. The effect of each pressure drop on the RED stack performance was identified and rationalized and guidelines for planning and/or optimization of RED stacks were derived. The design of new profiled membranes, with a chevron corrugation structure, was proposed using computational fluid dynamics (CFD) modeling. The performance of the suggested corrugation geometry was compared with the already existing ones, as well as with the use of conductive and non-conductive spacers. According to the estimations, use of chevron structures grants the highest net power density values, at the best compromise between the mass transfer coefficient and the pressure drop values. Finally, long-term experiments with natural waters were performed, during which fouling was experienced. For the first time, 2D fluorescence spectroscopy was used to monitor RED stack performance, with a dedicated focus on following fouling on ion-exchange membrane surfaces. To extract relevant information from fluorescence spectra, parallel factor analysis (PARAFAC) was performed. Moreover, the information obtained was then used to predict net power density, stack electric resistance and pressure drop by multivariate statistical models based on projection to latent structures (PLS) modeling. The use in such models of 2D fluorescence data, containing hidden, but extractable by PARAFAC, information about fouling on membrane surfaces, considerably improved the models fitting to the experimental data.

Assessing Cybersecurity service quality in corporate environments

This study assess the quality of Cybersecurity as a service provided by IT department in corporate network and provides analysis about the service quality impact on the user, seen as a consumer of the service, and on the organization as well. In order to evaluate the quality of this service, multi-item instrument ���SERVQUAL��� was used for measuring consumer perceptions of service quality. To provide insights about Cybersecurity service quality impact, DeLone and McLean information systems success model was used. To test this approach, data was collected from over one hundred users from different industries and partial least square (PLS) was used to estimate the research model. This study found that SERVQUAL is adequate to assess Cybersecurity service quality and also found that Cybersecurity service quality positively influences the Cybersecurity use and individual impact in Cybersecurity.

Development of process control strategies exploiting knowledge from systems biology: application to MDCK suspension cells

Madine Darby Canine Kidney (MDCK) cell lines have been extensively evaluated for their potential as host cells for influenza vaccine production. Recent studies allowed the cultivation of these cells in a fully defined medium and in suspension. However, reaching high cell densities in animal cell cultures still remains a challenge. To address this shortcoming, a combined methodology allied with knowledge from systems biology was reported to study the impact of the cell environment on the flux distribution. An optimization of the medium composition was proposed for both a batch and a continuous system in order to reach higher cell densities. To obtain insight into the metabolic activity of these cells, a detailed metabolic model previously developed by Wahl A. et. al was used. The experimental data of four cultivations of MDCK suspension cells, grown under different conditions and used in this work came from the Max Planck Institute, Magdeburg, Germany. Classical metabolic flux analysis (MFA) was used to estimate the intracellular flux distribution of each cultivation and then combined with partial least squares (PLS) method to establish a link between the estimated metabolic state and the cell environment. The validation of the MFA model was made and its consistency checked. The resulted PLS model explained almost 70% of the variance present in the flux distribution. The medium optimization for the continuous system and for the batch system resulted in higher biomass growth rates than the ones obtained experimentally, 0.034 h-1 and 0.030 h-1, respectively, thus reducing in almost 10 hours the duplication time. Additionally, the optimal medium obtained for the continuous system almost did not consider pyruvate. Overall the proposed methodology seems to be effective and both proposed medium optimizations seem to be promising to reach high cell densities.