Hygrothermal behaviour of earthen plasters for sustainable housing construction

A ready-mixed and several laboratory formulated mortars were produced and tested in fresh state and after hardening, simulating a masonry plaster for indoor application. All the mortars used a clayish earth from the same region and different compositions of aggregates, eventually including fibres and a phase change material. All the formulated mortars were composed by 1:3 volumetric proportions of earth and aggregate. Tests were developed for consistency, fresh bulk density, thermal conductivity, capillary absorption and drying, water vapour permeability and sorption-desorption. The use of PCM changed drastically the workability of the mortars and increased their capillary absorption. The use of fibres and variations on particle size distribution of the mixtures of sand that were used had no significant influence on tested properties. But particularly the good workability of these mortars and the high capacity of sorption and desorption was highlighted. With this capacity plasters made with these mortars are able to adsorb water vapour from indoor atmosphere when high levels of relative humidity exist and release water vapour when the indoor atmosphere became too dry. This fact makes them able to contribute passively for a healthier indoor environment. The technical, ecological and environmental advantages of the application of plasters with this type of mortars are emphasized, with the aim of contributing for an increased use for new or existent housing.

Process Engineering of Stem Cells for Clinical Application

Over the last decade, human embryonic stem cells (hESCs) have garnered a lot of attention owing to their inherent self-renewal ability and pluripotency. These characteristics have opened opportunities for potential stem cell-based regenerative medicines, for development of drug discovery platforms and as unique in vitro models for the study of early human development.(...)

Hydroxyapatite porous structures for bone tissue engineering

Esta dissertação teve como objetivo o desenvolvimento de espumas porosas de hidroxiapatite (HA) baseadas em réplicas invertidas de cristais coloidais (ICC) para substituição óssea. Um ICC é uma estrutura tridimensional de elevada porosidade que apresenta uma rede interconectada de poros com elevada uniformidade de tamanhos. Este tipo de arquitetura possibilita uma proliferação celular homogénea e superiores propriedades mecânicas quando comparada com espumas de geometria não uniforme. O cristal coloidal (CC) - o molde da espuma - foi criado por empacotamento de microesferas de poliestireno (270 μm) produzidas por microfluídica e posterior tratamento térmico. O molde foi impregnado com um gel de hidroxiapatite produzido via sol-gel utilizando pentóxido de fósforo e nitrato de cálcio tetrahidratado como percursores de fósforo e cálcio, respectivamente. A espuma cerâmica foi obtida num único passo depois de um tratamento térmico a 1100oC que permitiu a solidificação do gel e a remoção do CC. A análise por espetroscopia de infravermelho por transformada de Fourier (FTIR) e difração de raios-X (XRD) revelou uma hidroxiapatite carbonatada tipo A com presença de fosfatos tricálcicos. As propriedades mecânicas foram avaliadas por testes de compressão. A biocompatibilidade in vitro foi demonstrada através de testes de adesão e proliferação celular de osteoblastos.

Influence of the molecular weight in mechanical properties and degradation kinetics of chitosan inverted colloidal crystals

Tissue engineering arises from the need to regenerate organs and tissues, requiring the development of scaffolds, which can provide an optimum environment for tissue growth. In this work, chitosan with different molecular weights was used to develop biodegradable 3D inverted colloidal crystals (ICC) structures for bone regeneration, exhibiting uniform pore size and interconnected network. Moreover, in vitro tests were conducted by studying the influence of the molecular weight in the degradation kinetics and mechanical properties. The production of ICC included four major stages: fabrication of microspheres; assembly into a cohesive structure, polymeric solution infiltration and microsphere removal. Chitosan’s degree of deacetylation was determined by infrared spectroscopy and molecular weight was obtained via capillary viscometry. In order to understand the effect of the molecular weight in ICC structures, the mass loss and mechanical properties were analyzed after degradation with lysozyme. Structure morphology observation before and after degradation was performed by scanning electron microscopy. Cellular adhesion and proliferation tests were carried out to evaluate ICC in vitro response. Overall, medium molecular weight ICC revealed the best balance in terms of mechanical properties, degradation rate, morphology and biological behaviour.

Functional characterization and directed engineering of redox proteins for a rational improvement of Bioelectrochemical systems

In recent years, new methods of clean and environmentally friendly energy production have been the focus of intense research efforts. Microbial fuel cells (MFCs) are devices that utilize naturally occurring microorganisms that feed on organic matter, like waste water, while producing electrical energy. The natural habitats of bacteria thriving in microbial fuel cells are usually marine and freshwater sediments. These microorganisms are called dissimilatory metal reducing bacteria (DMRB), but in addition to metals like iron and manganese, they can use organic compounds like DMSO or TMAO, radionuclides and electrodes as terminal electron acceptors in their metabolic pathways.(...)

Determinants of Portuguese bank’s provisioning policies: Discretionary behaviour of generic and specific allowances

In this paper we test for the impact of the regulatory environment on a bank’s discretionary provisioning practices. We develop a model that structures the dynamics of the provision policy for the two classes of provisions: generic provisions and specific provisions. The model is tested using a comprehensive database of all financial institutions operating in Portugal for 1990-2000. This unique dataset comprises banks subject to the Portuguese rules as well as bank subsidiaries subject to their home-country regulation and we were able to identify distinct behaviours between them. Our results show the importance of handling he two types of provisions separately. They support the hypothesis that banks have a discretionary behaviour in setting up their provisions, and find evidence of income smoothing and capital management. We also find that the regulatory regime impacts on discretionary provisioning policies because banks when forced to increase one type of provision react by reducing the iscretionary component of the other, a finding we designated as a substitution effect.

Engineering of metal oxide nanoparticles for application in electrochemical devices

The growing demand for materials and devices with new functionalities led to the increased inter-est in the field of nanomaterials and nanotechnologies. Nanoparticles, not only present a reduced size as well as high reactivity, which allows the development of electronic and electrochemical devices with exclusive properties, when compared with thin films. This dissertation aims to explore the development of several nanostructured metal oxides by sol-vothermal synthesis and its application in different electrochemical devices. Within this broad theme, this study has a specific number of objectives: a) research of the influence of the synthesis parameters to the structure and morphology of the nanoparticles; b) improvement of the perfor-mance of the electrochromic devices with the application of the nanoparticles as electrode; c) application of the nanoparticles as probes to sensing devices; and d) production of solution-pro-cessed transistors with a nanostructured metal oxide semiconductor. Regarding the results, several conclusions can be exposed. Solvothermal synthesis shows to be a very versatile method to control the growth and morphology of the nanoparticles. The electrochromic device performance is influenced by the different structures and morphologies of WO3 nanoparticles, mainly due to the surface area and conductivity of the materials. The dep-osition of the electrochromic layer by inkjet printing allows the patterning of the electrodes without wasting material and without any additional steps. Nanostructured WO3 probes were produced by electrodeposition and drop casting and applied as pH sensor and biosensor, respectively. The good performance and sensitivity of the devices is explained by the high number of electrochemical reactions occurring at the surface of the na-noparticles. GIZO nanoparticles were deposited by spin coating and used in electrolyte-gated transistors, which promotes a good interface between the semiconductor and the dielectric. The produced transistors work at low potential and with improved ON-OFF current ratio, up to 6 orders of mag-nitude. To summarize, the low temperatures used in the production of the devices are compatible with flexible substrates and additionally, the low cost of the techniques involved can be adapted for disposable devices.

Essays in health economics: Volume-Outcome Effect, upcoding behaviour and the evaluation of a short-term intervention program

Evidence in the literature suggests a negative relationship between volume of medical procedures and mortality rates in the health care sector. In general, high-volume hospitals appear to achieve lower mortality rates, although considerable variation exists. However, most studies focus on US hospitals, which face different incentives than hospitals in a National Health Service (NHS). In order to add to the literature, this study aims to understand what happens in a NHS. Results reveal a statistically significant correlation between volume of procedures and better outcomes for the following medical procedures: cerebral infarction, respiratory infections, circulatory disorders with AMI, bowel procedures, cirrhosis, and hip and femur procedures. The effect is explained with the practice-makes-perfect hypothesis through static effects of scale with little evidence of learning-by-doing. The centralization of those medical procedures is recommended given that this policy would save a considerable number of lives (reduction of 12% in deaths for cerebral infarction).

Analysis of chromium behaviour and speciation during the electrodialytic process

The interest in chromium (Cr) arises from the widespread use of this heavy metal in various industrial processes that cause its release as liquid, solid and gaseous waste into the environment. The impact of Cr on the environment and living organisms primarily depends on its chemical form, since Cr(III) is an essential micronutrient for humans, other animals and plants, and Cr(VI) is highly toxic and a known human carcinogen. This study aimed to evaluate if the electrodialytic process (ED) is an appropriate treatment for Cr removal, through a critical overview of Cr speciation, before and after the ED experiments, to assess possible Cr(III)-Cr(VI) interconversions during the treatment. ED was the treatment technique applied to two types of matrices containing Cr: chromate copper arsenate (CCA) contaminated soil and municipal solid waste incineration (MSWI) fly ash. In order to study Cr remediation, three EDR set-ups were used: a new set-up, the combined cell (2/3C or 3/2C), with three compartments, alternating current between two anodes and different initial experimental conditions, one set-up with three compartments (3C cell) and the other set-up with two compartments (2C cell). The Cr removal rates obtained in this study were between 10-36% for the soil, and 1-13% for the fly ash. The highest Cr removal rates were achieved in the 26 days experiments: 36% for the soil, 13% for the fly ash. Regarding the 13 days experiments, the highest Cr removal rates were attained with the 2/3C set-up: 24% for the soil, 5% for the fly ash. The analysis of Cr(VI) was performed before and after ED experiments to evaluate eventual changes in Cr speciation during the treatment. This analysis was conducted by two methods: USEPA Method 3060A, for the extraction of Cr(VI); and Hach Company Method 8023, for the detection of Cr(VI). Despite the differences in Cr total concentration, both matrices presented a similar speciation, with Cr(III) being the main species found and Cr(VI) less than 3% of Cr total, before and after the treatment. For fly ash, Cr(VI) was initially below the detection limit of the method and remained that way after the treatment. For soil, Cr(VI) decreased after the treatment. Oxidation of Cr(III) to Cr(VI) did not occur during the ED process since there was no increase in Cr(VI) in the matrices after the treatment. Hence, the results of this study indicate that ED is an appropriate technique to remediate matrices containing Cr because it contributes to Cr removal, without causing Cr(III)-Cr(VI) interconversions.

Analysis of a controversial decision process: the case of the pumped hydro storage power plant Atdorf in Germany

Based on the report for the unit “Métodos Interactivos de Participação e Decisão A” (Interactive methods of participation and decision A), coordinated by Prof. Lia Maldonado Teles de Vasconcelos and Prof. Nuno Miguel Ribeiro Videira Costa. This unit was provided for the PhD Program in Technology Assessment in 2015/2016.

Engineering bio-based polymers using alternative solvents and processes

The work presented in this thesis explores novel routes for the processing of bio-based polymers, developing a sustainable approach based on the use of alternative solvents such as supercritical carbon dioxide (scCO2), ionic liquids (ILs) and deep eutectic solvents (DES). The feasibility to produce polymeric foams via supercritical fluid (SCF) foaming, combined with these solvents was assessed, in order to replace conventional foaming techniques that use toxic and harmful solvents. A polymer processing methodology is presented, based on SCF foaming and using scCO2 as a foaming agent. The SCF foaming of different starch based polymeric blends was performed, namely starch/poly(lactic acid) (SPLA) and starch/poly(ε-caprolactone) (SPCL). The foaming process is based on the fact that CO2 molecules can dissolve in the polymer, changing their mechanical properties and after suitable depressurization, are able to create a foamed (porous) material. In these polymer blends, CO2 presents limited solubility and in order to enhance the foaming effect, two different imidazolium based ILs (IBILs) were combined with this process, by doping the blends with IL. The use of ILs proved useful and improved the foaming effect in these starch-based polymer blends. Infrared spectroscopy (FTIR-ATR) proved the existence of interactions between the polymer blend SPLA and ILs, which in turn diminish the forces that hold the polymeric structure. This is directly related with the ability of ILs to dissolve more CO2. This is also clear from the sorption experiments results, where the obtained apparent sorption coefficients in presence of IL are higher compared to the ones of the blend SPLA without IL. The doping of SPCL with ILs was also performed. The foaming of the blend was achieved and resulted in porous materials with conductivity values close to the ones of pure ILs. This can open doors to applications as self-supported conductive materials. A different type of solvents were also used in the previously presented processing method. If different applications of the bio-based polymers are envisaged, replacing ILs must be considered, especially due to the poor sustainability of some ILs and the fact that there is not a well-established toxicity profile. In this work natural DES – NADES – were the solvents of choice. They present some advantages relatively to ILs since they are easy to produce, cheaper, biodegradable and often biocompatible, mainly due to the fact that they are composed of primary metabolites such as sugars, carboxylic acids and amino-acids. NADES were prepared and their physicochemical properties were assessed, namely the thermal behavior, conductivity, density, viscosity and polarity. With this study, it became clear that these properties can vary with the composition of NADES, as well as with their initial water content. The use of NADES in the SCF foaming of SPCL, acting as foaming agent, was also performed and proved successful. The SPCL structure obtained after SCF foaming presented enhanced characteristics (such as porosity) when compared with the ones obtained using ILs as foaming enhancers. DES constituted by therapeutic compounds (THEDES) were also prepared. The combination of choline chloride-mandelic acid, and menthol-ibuprofen, resulted in THEDES with thermal behavior very distinct from the one of their components. The foaming of SPCL with THEDES was successful, and the impregnation of THEDES in SPCL matrices via SCF foaming was successful, and a controlled release system was obtained in the case of menthol-ibuprofen THEDES.

The value creation radar applied to the space engineering sector

This case study illustrates the application of the Value Creation Radar (VCR) to SenSyF, an Earth Observation (EO) system which was developed by Deimos Engenharia S.A. (DME), the Portuguese affiliate of Elecnor Deimos. It describes how a team of consultants adopted the VCR in order to find new market applications for SenSyF, selected the one with the highest potential, and defined a path to guarantee a sustainable market launch. This case study highlights the main challenges of bringing a technology-driven company closer to the market in the pursuit of long-term sustainability, while not compromising its technological capabilities

From user browsing behaviour to user demographics

A Internet conta hoje com mais de 3 mil milhões de utilizadores e esse valor não para de aumentar. Desta forma, proporcionar uma experiência online agradável aos seus utilizadores é cada vez mais importante para as empresas. De modo a tirar partido dos benefícios deste crescimento, as empresas devem ser capazes de identificar os seus clientes-alvo dentro do total de utilizadores; e, subsequentemente, personalizar a sua experiência online. Existem diversas formas de estudar o comportamento online dos utilizadores; no entanto, estas não são ideais e existe uma ampla margem para melhoria. A inovação nesta área pode comportar um grande potencial comercial e até ser disruptiva. Com isto em mente, proponho-me a estudar a possível criacão de um sistema de aprendizagem automática (machine learning) que permita prever informa ações demográficas dos utilizadores estritamente com base no seu comportamento online. Tal sistema poderia constituir uma alternativa às atuais opções, que são mais invasivas; mitigando assim preocupações ao nível da proteção de dados pessoais. No primeiro capítulo (Introdução) explico a motivação para o estudo do comportamento dos utilizadores online por parte de empresas, e descrevo as opções disponíveis atualmente. Apresento também a minha proposta e o contexto em que assenta. O capítulo termina com a identicação de limitações que possam existir a priori. O segundo capítulo (Machine Learning) fornece uma introdução sobre machine learning, com o estudo dos algoritmos que vão ser utilizados e explicando como analisar os resultados. O terceiro capítulo (Implementação) explica a implementação do sistema proposto e descreve o sistema que desenvolvi no decorrer deste estudo, e como integra-lo em sistemas já existentes. No quarto capítulo (Análise e manipulação dos dados), mostro os dados compilados e explico como os recolhi e manipulei para testar a hipótese. No quinto capítulo (Análise de dados e discussão) vemos como e que os dados recolhidos foram usados pelos vários algoritmos para descobrir como se correlacionam com dados dos utilizadores e analiso e discuto os resultados observados. Por fim, o sexto e último capítulo apresenta as conclusões. Dependendo dos resultados, mostro como a hipótese poderia ser melhor testada, ou então discuto os próximos passos para tornar o sistema realidade.