Characterization of polymeric membranes for non-aqueous separations

The industrial application of solvent resistant nanofiltration (SRNF) membranes for solvent purification has grown considerably in the last decade. The number of solvent/membrane systems is increasing and consequently, the need for characterization of chemical and physical phenomena, i.e. sorption, swelling, compaction and mobility. This thesis provides a tool box with characterization methods that are aimed to be independent of the solvent and membrane material and to provide results focused on the transport determining layer of the membrane. In Chapter 2 the determining transport mechanism of three similar solvents (methanol, ethanol and 1-butanol) in a silicon-type SRNF membrane has been studied. The results suggest that diffusion alone can not explain the transport of alcohols and an additional transport mechanism takes place. Assuming the additional mechanism to be viscous in nature allows a fit of a flux expression to the experimental data using one single fitting parameter. For 1-butanol, the contribution of the additional mechanism is only small. In contrast, for the smaller methanol and ethanol the contribution of viscous flow is very high. This is in contrast with observations in literature for similar systems, signifying a limited applicability of state-of-the-art models for predicting solvent transport through SRNF membranes. Chapter 3 presents a generic method that allows the determination of retention behavior in non-aqueous solvent filtration. The method has limited restrictions with respect to solute solubility and is independent of the solvent studied. Using a low concentration of polyethylene glycol 1000 with a broad molecular weight distribution, combined with a powerful analytical technique such as mass spectroscopy, a single retention experiment produces a full retention curve. In this way, the molecular weight cut-off (MWCO) of a membrane can be directly determined and the cost and time of the experimental procedure is reduced. Retention has been shown to be mostly dependent on the rate and mechanism of solvent transport. For transport that is solely or partially viscous, dragging effects cause the retention of small PEG oligomers to be low. For transport determined by diffusion, dragging effects are insignificant and retention is high (98%) irrespective of the size and shape of the solute molecule. Chapters 4 and 6 show the versatility of attenuated total reflectance spectroscopy infrared (ATR-IR) to determine in-situ sorption and compaction in the active layer of a cellulose acetate (CA) membrane and a silicon-type SRNF membrane, respectively. Preferential sorption of water has been measured in a CA membrane for water/methanol and water/ethanol mixtures. The results are in accordance with literature. The extent of compaction of the transport determining layer of the commercial SRNF membrane has been determined under different pressure conditions. Results show that reduction in thickness of the entire membrane can not be directly related to the reduction in density of the active layer. Comparison with permeation experiments under the same conditions show the importance of measuring both swelling and compaction simultaneously. Chapter 5 shows the development of two straightforward techniques to measure swelling: mechanically using a micrometer and optically using an interferometer. Both methods allow the study of the dynamic swelling behavior and yield similar results. Different polymer layers present in the membrane show different contributions to swelling. Comparison of the dynamics of swelling and sorption reveals that these two phenomena, although interdependent, do not start simultaneously and are not comparable in magnitude. For this reason, if the extent of sorption is interpreted as a direct measure for the extent of swelling, incorrect conclusions can be drawn. Chapter 7 concludes the thesis by taking a look at the impact of the work developed. Furthermore, the future possibilities for developments regarding the characterization, prediction and process monitoring are discussed

Arabinogalactan Proteins as Interactors along the Crosstalk between the Pollen Tube and the Female Tissues

Arabinogalactan proteins (AGPs) have long been considered to be implicated in several steps of the reproductive process of flowering plants. Pollen tube growth along the pistil tissues requires a multiplicity of signaling pathways to be activated and turned off precisely, at crucial timepoints, to guarantee successful fertilization and seed production. In the recent years, an outstanding effort has been made by the plant reproduction scientific community in order to better understand this process. This resulted in the discovery of a fairly substantial number of new players essential for reproduction, as well as their modes of action and interactions. Besides all the indications of AGPs involvement in reproduction, there were no convincing evidences about it. Recently, several studies came out to prove what had long been suggested about this complex family of glycoproteins. AGPs consist of a large family of hydroxyproline-rich proteins, predicted to be anchored to the plasma membrane and extremely rich in sugars. These two last characteristics always made them perfect candidates to be involved in signaling mechanisms, in several plant developmental processes. New findings finally relate AGPs to concrete functions in plant reproduction. In this review, it is intended not only to describe how different molecules and signaling pathways are functioning to achieve fertilization, but also to integrate the recent discoveries about AGPs along this process

Tackling tourism-driven development in World Heritage cities: A comparison between Macao, China and Evora, Portugal

World Heritage cities, all over the world, are a centre of tourist attraction. In many of these cities, tourism is one of the main driving forces of local economies. As a result, these cities come under intense pressure to accommodate tourism-driven developments; summed up with the pressure to fulfil the needs of local communities. How development in World Heritage cities can be tackled is, thus, an important issue for both heritage management and urban development. This paper presents two World Heritage cities – Macao, a former Portuguese colony in China and Évora, the capital of Alentejo region in Portugal - as case studies and discusses and compares the way tourism-driven development is being tackled in these cities. Macao’s economy depends almost entirely on tourism-driven activities. While the World Heritage status has added additional attractiveness to Macao, the main attraction there is gambling. On the other hand, Évora is much less dependent on tourism. Similar to Macao, the World Heritage status has raised the attractiveness of Évora as a tourist destination; however, the university plays also a fundamental role. Consequently, despite the efforts of the local authorities, the city is losing its local community. Even if for different reasons, in both case studies, heritage is often sidelined in the urban development agenda. The case studies identify the raise of cultural-driven tourism and the consequent urban developments and illustrate the role of legislations and regulations and the impact of their variation per heritage protection zones. Moreover, it identifies the resultant urban development scenario that enhance or diminish the heritage values of the cities and, therefore, help retain or cause destruction to the very cultural capital that has brought and can bring many more benefits to these cities of outstanding universal value

Tackling tourism-driven development in World Heritage cities: A comparison between Macao, China and Evora, Portugal

World Heritage cities, all over the world, are a centre of tourist attraction. In many of these cities, tourism is one of the main driving forces of local economies. As a result, these cities come under intense pressure to accommodate tourism-driven developments; summed up with the pressure to fulfil the needs of local communities. How development in World Heritage cities can be tackled is, thus, an important issue for both heritage management and urban development. This paper presents two World Heritage cities – Macao, a former Portuguese colony in China and Évora, the capital of Alentejo region in Portugal - as case studies and discusses and compares the way tourism-driven development is being tackled in these cities. Macao’s economy depends almost entirely on tourism-driven activities. While the World Heritage status has added additional attractiveness to Macao, the main attraction there is gambling. On the other hand, Évora is much less dependent on tourism. Similar to Macao, the World Heritage status has raised the attractiveness of Évora as a tourist destination; however, the university plays also a fundamental role. Consequently, despite the efforts of the local authorities, the city is losing its local community. Even if for different reasons, in both case studies, heritage is often sidelined in the urban development agenda. The case studies identify the raise of cultural-driven tourism and the consequent urban developments and illustrate the role of legislations and regulations and the impact of their variation per heritage protection zones. Moreover, it identifies the resultant urban development scenario that enhance or diminish the heritage values of the cities and, therefore, help retain or cause destruction to the very cultural capital that has brought and can bring many more benefits to these cities of outstanding universal value

Alterações do tecido muscular com o envelhecimento

Sarcopenia is characterized by a progressive generalized decrease of skeletal muscle mass, strength and function with aging. Recent- ly, the genetic determination has been associated with muscle mass and muscle strength in elderly. These two phenotypes of risk are the most commonly recognized and studied for sarcopenia, with heritability ranging from 30 to 85% for muscle strength and 45-90% for muscle mass. It is well known that the development and maintenance of muscle mass in early adulthood reduces the risk of developing sarcopenia and leads to a healthy aging. For that reason it seems important to identify which genetic factors interact with aging and in particular with the musculoskeletal response to exercise in such individuals. This review is designed to summarize the most important and representative studies about the possible association between certain genetic polymorphisms and muscle phenotypes in older populations. Also we will focuses on nutrition and some concerns associated with aging, including the role that exercise can have on reducing the negative effects of this phenomenon. Some results are inconsis- tent between studies and more replication studies underlying sarcopenia are needed, with larger samples and with different life cycles, particularly in the type and level of physical activity throughout life. In future we believe that further progress in understanding the ge- netic etiology and the metabolic pathways will provide valuable information on important biological mechanisms underlying the muscle physiology. This will enable better recognition of individuals at higher risk and the ability to more adequately address this debilitating condition.Sarcopenia é caracterizada por uma diminuição generalizada e progressiva da força, massa e função muscular com o envelhecimento. Recentemente, a determinação genética tem sido associada com a massa muscular e força muscular em idosos. Estes dois fenótipos de risco são os mais comumente reconhecidos e estudados em relação à sarcopenia, com hereditariedade variando de 30 a 85% para a força muscular e 45-90% para a massa muscular. É bem conhecido que o desenvolvimento e manutenção da massa muscular na idade adulta reduz o risco de desenvolver sarcopenia e conduz a um envelhecimento saudável. Por isso, é importante identificar quais os fatores genéticos que interagem com o envelhecimento e, em particular, com a resposta músculo-esquelética ao exercício. Esta revisão destina-se a resumir os estudos mais importantes e representativos sobre a possível associação entre determinados polimorfismos genéticos e fenótipos musculares nas populações mais velhas. Os aspetos nutricionais serão discutidos, incluindo o papel que o exercício pode ter sobre a redução dos efeitos negativos deste fenômeno. Alguns resultados são inconsistentes e desta forma é necessária uma maior replicação subjacente à sarcopenia, com amostras maiores e em diferentes ciclos da vida, especial- mente no tipo e nível de atividade física. No futuro, acreditamos que mais progressos na compreensão da etiologia genética e as vias metabólicas vai fornecer informações valiosas sobre importantes mecanismos biológicos envolvidos na fisiologia muscular. Isto irá permitir um melhor reconhecimento dos indivíduos com maior risco e uma maior capacidade de enfrentar adequadamente essa condição debilitante

Alterações músculo-esqueléticas relacionadas com o envelhecimento: causas e consequências

O aumento da população idosa e a crescente procura de tratamentos mais adequados para aliviar a dor causada pelos fatores que caracterizam o envelhecimento, particularmente a instalação da sarcopenia, condição associada ao sedentarismo e em alguns casos a enfermidades como artrites e artrose, são responsáveis pelo desenvolvimento de dores articulares que impossibilitam a prática de exercício físico, despoletando outros riscos como a osteoporose e perda da estabilidade postural que em conjunto aumentam o risco de quedas, lesões e fraturas associadas (Powers & Howley, 1997). Porém, a sua origem deverá ser igualmente interpretada muitas vezes como consequência das crescentes limitações do foro ortopédico. A inatividade conduz a um desuso do sistema músculo-esquelético e naturalmente a uma hipo-estimulação do tecido muscular conduzindo à atrofia do mesmo com diminuição da sua função (Tavares, C. 2003). Um exemplo categórico é o caso da osteoartrose do joelho, uma patologia articular crónica degenerativa, frequente em adultos e idosos que interfere na mobilidade e autonomia. A osteoartrose é caracterizada pela presença de dor e limitação funcional, consequência da formação de osteófitos e/ou alteração na integridade da cartilagem articular, que conduzem a uma perda gradual da força, diminuição da mobilidade e instabilidade articular. Frequentemente assistimos nos indivíduos com esta patologia a uma diminuição gradual nos seus níveis de atividade física, já que a imobilização da articulação contribui para diminuir o processo inflamatório na mesma, diminuindo também a dor. No entanto, a imobilização da articulação com artrose vai potenciar: a atrofia, o encurtamento de músculos e tendões, o surgimento de contracturas, a perda de massa óssea, o aumento do risco de fratura, a redução da mobilidade articular e a degeneração da cartilagem (Gordon, N., 1992). Assim, a inatividade física torna-se contraproducente, sendo a prescrição de exercício físico adequado uma forma de combater o avanço progressivo da doença. O fortalecimento da musculatura peri articular é fundamental para a obtenção do equilíbrio da articulação, controlando o impacto do pé sobre o solo durante a marcha, lubrificando a articulação e reduzindo os movimentos anormais entre as superfícies articulares o que ajuda a diminuir a degeneração da articulação (Roddy, E., W. Zhang, and M. Doherty, 2005). A manutenção do equilíbrio é um aspeto determinante na funcionalidade e autonomia estando relacionado como o sistema visual, somatosensorial e vestibular, com a força dos membros inferiores, nomeadamente os grupos musculares flexores e extensores das articulações do joelho e tibiotársica, que tendem a diminuir com a idade. Além disso, as alterações degenerativas dos discos intervertebrais, somados à diminuição da flexibilidade e da força das estruturas musculares e das posturas incorretas frequentes, conduzem a desalinhamentos nas curvaturas da coluna que por sua vez contribuem para a deterioração do equilíbrio, não só estático, como também dinâmico, e consequentemente do padrão de marcha. Neste contexto, a realização de atividade física é fundamental na prevenção de quedas e de fraturas associadas, tendo sido demonstrado por vários estudos que a participação em programas de exercício e o treino de tarefas especificamente orientadas para o sistema sensorial e a manutenção da estabilidade postural reduzem significativamente o número de quedas quando comparado a grupos de controlo, tanto em homens como em mulheres (Izquierdo et al., 2005; 2004). Em suma, o treino da força com intensidade moderada a elevada pode ser efetuado com elevada tolerância por parte de adultos e idosos, com resultados bastante satisfatórios em termos de adaptação morfológica e funcional, assim como também em termos de propriedades elétricas e contrácteis.

Photo and electroluminescence behavior of Tb(ACAC)3phen complex used as emissive layer on organic light emitting diodes

This work shows the luminescence properties of a rare-earth organic complex, the Tb(ACAC)3phen. The results show the 5D4 -> 7F3,4,5,6 transitions with no influence of any ligand emission. The photoluminescence excitation spectrum is tentatively interpreted by the ligands absorption. An OLED was made by thermal evaporation (total thickness of 1200 Å) using TPD and Alq3 as hole and electron transport layers, respectively. The light emission reproduces the photoluminescence spectrum of the terbium complex at room temperature, with CIE (x,y) color coordinates of (0.28, 0.55). No presence of any bands from the ligands was observed. The potential use of this compound in efficient devices is discussed

Comparação electromiográfica do passe e do remate em Futsal

Foi objectivo deste trabalho comparar a actividade neuromuscular do membro inferior na execução do remate e do passe com o dorso do pé no Futsal. Estudaram-se 5 sujeitos do sexo masculino e federados com idades compreendidas entre os 20 e os 26 anos. Foram analisadas duas condições de execução: o passe e o remate. O passe foi efectuado para um jogador colocado à sua frente e a seis metros de distância. O remate foi efectuado a uma distância de seis metros com oposição de um guarda-redes. Os dados electromiográficos foram recolhidos através de eléctrodos bipolares pré-amplificados colocados no Vasto interno, Vasto externo, Gastrocnémio medial e Tibial anterior com uma frequência de aquisição de 1 kHz. O sinal foi processado digitalmente, a fim de se obter o valor quadrático médio (RMS). A RMS foi normalizada individualmente com base no valor máximo dentro de uma determinada condição de exercitação. Um electrogoniómetro foi colocado entre a perna e a coxa para determinação dos parâmetros cinemáticos. A frequência de aquisição foi de 1 kHz e os dados estavam sincronizados com o sinal electromiográfico. Foram avaliados o ângulo relativo mínimo entre a perna e a coxa, assim como, o valor máximo da velocidade angular entre a perna e coxa. A velocidade foi significativamente superior e o ângulo significativamente inferior no remate do que no passe. A actividade neuromuscular foi significativamente superior no remate do que no passe em todos os grupos musculares estudados

Incidence of late vitamin K deficiency bleeding in newborns in the Netherlands in 2005: evaluation of the current guideline

Vitamin K prophylaxis is recommended to prevent the hazard of haemorrhage caused by vitamin K deficiency in newborns. The present Dutch guideline recommends 1 mg of vitamin K1 orally at birth, followed by a daily dose of 25 μg of vitamin K1 from 1 to 13 weeks of age for breastfed infants. Since the introduction of this prophylaxis, the incidence of vitamin K deficiency bleeding (VKDB) has decreased; however, late VKDB is still reported. From 1 January to 31 December 2005, a nationwide active surveillance was performed by the Netherlands Paediatric Surveillance Unit (NSCK) to study the current incidence and aetiology of late VKDB in infants. Six cases could be validated as late VKDB: all were breastfed, one fatal idiopathic intracranial haemorrhage at the age of 5 weeks and five bleedings secondary to an underlying cholestatic liver disease between the age of 3 and 7 weeks. The total incidence of late VKDB and idiopathic late VKDB was calculated to be 3.2 (95% CI: 1.2–6.9) and 0.5 (95% CI: 0–2.9) per 100,000 live births, respectively. With the current Dutch guideline, idiopathic late VKDB is rare but late VKDB secondary to cholestasis still occurs in breastfed infants. Doubling the daily dose of vitamin K1 to 50 μg, as is comparable to formula-feeding, may possibly prevent VKDB in this group. Further research, however, is needed to prove this hypothesis