O carácter vernáculo na construção com terra no panorama contemporâneo

Dissertação de Mestrado Integrado em Arquitetura, com a especialização em Arquitetura, apresentada na Faculdade de Arquitetura da Universidade de Lisboa para obtenção do grau de Mestre.N/

Development of biocompatible and “smart” porous structures using CO2-assisted processes

Dissertação apresentada para a obtenção do grau de Doutor em Engenharia Química, especialidade Engenharia da Reacção Química, pela Universidade Nova de Lisboa, Faculdade de Ciências e TecnologiaOver the past three decades the use of supercritical carbon dioxide (scCO2) has received much attention as a green alternative in the synthesis and processing of polymers. The scope of this thesis is the development of biocompatible and “smart” porous structures using CO2-assisted processes. This thesis is organized in four main chapters. The first one reviews and highlights some potentialities of supercritical fluid technology and the following ones compile the experimental work developed. The work is divided in three main parts: in the first part (2nd chapter) a CO2-assisted phase inversion method was developed in order to prepare porous structures, namely membranes. In the second part (3rd chapter) the focus was the synthesis of “smart” polymers,especially thermo and pH sensitive polymers. Finally, these two areas were combined (4th chapter) for the preparation of “smart” porous structures. The common guide line was the preparation or processing of biodegradable and/or biocompatible materials with special emphasis on the preparation of porous matrices, namely membranes and scaffolds, with controlled morphology. For membrane preparation a new high pressure apparatus and a new high pressure cell were developed. Polysulfone membranes (a biocompatible polymer with numerous applications in the medical field) were prepared and the effect of the solvent affinity and depressurization rate in the morphology and in the performance in terms of pure water flux of the membranes was investigated. The incorporation of a foaming agent was also analyzed and the high pressure CO2 capability to swell and melt polycaprolactone (PCL) was used to produce and control the porosity and the properties of the membranes. Finally, a natural and water soluble polymer (chitosan) was processed. The presence of water in the casting solution introduced extraordinary difficulties due to the low affinity between water and CO2. To induce the phase inversion a co-solvent (ethanol)was introduced in the CO2 stream. The obtained devices (membranes and beads) were fabricated using moderate temperatures and “green” solvents (ethanol, water and CO2). The morphology and the three dimensional (3D) structures were controlled by altering the co-solvent (ethanol) composition in the CO2 non-solvent stream during the demixing induced process. Microarchitectural analysis by scanning electron microscopy identified the formation of particulate agglomerates when 10% of ethanol in the scCO2 stream was used and detected the development of porous membranes with different morphologies and mechanical properties depending on the programmed gradient mode and the entrainer percentage (2.5-5%) added to the scCO2 stream. These chitosan matrices exhibited low solubility at neutral pH conditions, with no further modifications, demonstrating their applicability in bioreactors as static (membranes) or stirred (beads) culture devices. It was also demonstrated that the current method is able to prepare, in a single-step, an implantable antibiotic release system by co-dissolving gentamicin with chitosan and the solvent. In addition, the cytotoxicity as well as the ability of these structures to support the adhesion and proliferation of human mesenchymal stem cells (hMSC) in vitro were also addressed. After 2 weeks in culture, a 9-fold increase was obtained (versus 6 of the control). More importantly, cells maintained their clonogenic potential and immunophenotype (>95% CD 105+ Cells after 7 days of culture). In this chapter, a hypothetical schematic ternary diagram for the systems polymer–solvent–CO2 is used to discuss and explain the results. Another goal of this thesis was the synthesis of “smart” polymers. Chapter 3, addresses the precipitation polymerization of a thermoresponsive hydrogel, poly(N-isopropylacrylamide)(PNIPAAm), in scCO2. This hydrogel has a transition temperature, hereinafter called low critical solution temperature (LCST), around 32 ºC in an aqueous solution, close to body temperature. A strategy of solvent-free impregnation/coating of polymeric surfaces with PNIPAAm was suggested, in order to further extend the applications of membranes or porous bulky systems. The in situ synthesis of PNIPAAm within a chitosan scaffold was tested as a proof of concept, in order to produce smart partially-biodegradable scaffolds for tissue engineering applications. The LCST was tuned by copolymerization or graft polymerization of NIPAAm with other monomers. Copolymerization with hydroxyethyl methacrylate (HEMA) was used to decrease the LCST temperature from 32.2 ºC to approximately 27.7 ºC. Cloud point measurements of CO2 + HEMA system were used to optimize the polymerization temperature. Experimental data were obtained at 40 ºC, 50 ºC and 65 ºC and pressures up to 21.1 MPa. Soave-Redlich-Kwong equation of state with Mathias-Klotz-Prausnitz mixing rule was used to model experimental results and a good correlation was achieved. To increase the LCST, polyethylene oxide (an hydrophilic polymer) was grafted to PNIPPAAm. Dual stimulus (thermo and pH responsive) hydrogels were also prepared by copolymerizing methacrylic acid with PNIPAAm. As a proof of concept fluorouracil was incorporated in the hydrogels network and their release was controlled by temperature and pH stimulus. In chapter 4 the concepts of the previous chapters were put together envisaging the preparation of“smart” functional polymeric devices with targeted physical and chemical properties namely: (i) chitosan-based dual stimulus scaffolds (temperature and pH responsive); (ii) polysulfone-based thermoresponsive membranes and (iii) polymethylmethacrylate-based membranes. The chitosan scaffolds (pH sensitive) were coated/impregnated with a thermoresponsive polymer,poly(N-isopropylacrylamide) (PNIPAAm), using scCO2 as a carrier to homogeneously distribute the hydrogels monomer within the chitosan scaffolds and as a solvent to perform the polymerization reaction.Fundação para a Ciência e Tecnologia através da bolsa de Doutoramento (SFRH/BD/16908/2004) e do projecto PTDC/CTM/70513/200

Rompiendo la “maldición de los vacíos fronterizos”: La construcción de la fisionomía urbana de Berlín a través de la “fachada bien ordenada” del viaducto ferroviario

This article unfolds the analysis of the railway viaduct that crosses the German capital in an eastern-western direction. The aim is to decipher the urban design strategies used in the highl planned Stadtbahn, focusing on the configuration of Berlin’s urban physiognomy through a “well-ordered facade”. Thus exposing the morphologically linear construction associated with transport infrastructure, making clear the railway project design as a building-viaduct, imposing its architectural façade’s scenic effects on the surrounding public space. Through an in situ survey it is left clear that this building-viaduct, has the ability to break the “curse of border vacuums”, counteracting the destruction of neighboring areas that typically converts the segregated path into a physical and social border route. The intention is to clarify the value that architecture adds to these infrastructures originated as an accurate response to specific problems of time and distance, enlightening a multidisciplinary field which becomes increasingly unavoidable, where the contribution of architects is still very much diffused. El presente artículo se despliega sobre el análisis del viaducto ferroviario que atraviesa el centro de la capital alemana en la dirección este-oeste. Con ello se pretende descifrar las estrategias de diseño urbano vinculadas a la planificación elevada de la Stadtbahn, discurriéndose sobre la configuración de la fisionomía urbana del centro de Berlín a través de una “fachada bien ordenada”. Así se expone la construcción de una morfología lineal asociada a la infraestructura de transporte segregado, aclarándose el designio de proyectar la línea de tren como un edificio-viaducto, que subordina la composición del espacio público a los efectos escénicos de su frontón arquitectónico. A través de un levantamiento in situ se deja de manifiesto que dicho edifico tiene la capacidad de romper la “maldición de los vacíos fronterizos”, contrariando la destrucción de las vecindades que típicamente convierte la vía segregada en una frontera físico-social. Esto con la intención de despejar el valor que la arquitectura agrega a estas construcciones originadas como respuesta exacta a problemas concretos de tiempo y distancia recogida, alumbrando un campo de trabajo multidisciplinario cada vez más ineludible, donde el aporte de los arquitectos al problema de la infraestructura de transporte aparece aún como figura difusa.

Agricultural Knowledge Management System Development for Knowledge Integration

Agricultural KMS development involves various participants from different communities of practice (CoPs) who possess their own knowledge. However, the current development of technology neglected the local communities who possess indigenous knowledge, which is the key success factor for agricultural development. This study aims at contributing in the discourse on how to integrate scientific and IK in agricultural KMS development and use. An interpretive analysis of primary qualitative data acquired through in-depth semi-structured interviews and participant observations was carried out following system development action research approach. The research result yields concepts for understanding the process conceptual framework in KMS development and use for knowledge sharing and integration

De la marginalidad del oído a la construcción auditiva del paisaje urbano

Centrado en el valor heurístico de las sonoridades, el presente artículo procura compilar algunos atributos fundamentales para la definición acústica del paisaje. Se trata de un recorrido que se inicia en la marginalidad del sentido auditivo promovida por la “sordera” de las ciencias sociales, hasta llegar al concepto de “soundspace” acuñado por el musicólogo canadiense Murray Schafer. De este modo se intenta descifrar como el paisaje se reintroduce en la agenda de la geografía y otros dominios del conocimiento, pasando a ser entendido como un constructo cultural donde los sonidos dan carácter al espacio y lo “humanizan”. Aquí se explicita el carácter antropocéntrico del paisaje sonoro, demostrándose como la biografía sonora del espacio se confunde con la memoria autobiográfica de quien escucha. De esta manera se procura aclarar de qué manera el sonido caracteriza y atribuye sentido a un determinado lugar, discurriéndose sobre los conceptos de imagen e identidad sonora del paisaje. Esto para demostrar, conclusivamente, que la componente ordinaria de dicha identidad tiende a estandarizar las señales patrimoniales de la “música de la ciudad”, conllevando al aparecimiento de un paisaje urbano genérico, producido por el “cosmopolitismo sonoro” característico de la ciudad contemporánea.Paisaje sonoro_ Imagen sonora_ Identidad sonora_ Música de la ciudad _ Cosmopolitismo sonoro_ Paisaje urbanoFocused on the heuristic value of the sounds, this article seeks to compile some fundamental attributes for the landscape’s acoustic definition. This is a journey that starts in the marginality of the auditive sense, promoted by the "deafness" of the social sciences, until the purview of the "soundspace" concept, coined by the Canadian musicologist Murray Schafer. This way, we try to decipher how the landscape is reintroduced in the geography´s agenda and other domains of knowledge, understanding it then, as a cultural construct, where sounds give character to the space and "humanise" it. Here, we try to reveal the anthropocentric character of the sonorous landscape, demonstrating how the soundspace biography is confused with the autobiographical memory of whoever listens. This way, we seek to clarify how the sound characterizes and gives a meaning to a particular place, explaining the concepts of image and sonorous identity of the landscape. This to conclusively demonstrate that the ordinary component of such identity tends to standardize the patrimonial signals of the "music of the city", leading to the emergence of a generic urban landscape, produced by the "sound cosmopolitanism", characteristic of the contemporary city.Soundscape__ Sonorous Identity _ Music of the city _ Cosmopolitanism sound_ Urban Landscap

Supercritical phase inversion of starch-poly(e-caprolactone) for tissue engineering applications

In this work, a starch-based polymer, namely a blend of starch-poly(ε-caprolactone) was processed by supercritical assisted phase inversion process. This processing technique has been proposed for the development of 3D structures with potential applications in tissue engineering applications, as scaffolds. The use of carbon dioxide as non-solvent in the phase inversion process leads to the formation of a porous and interconnected structure, dry and free of any residual solvent. Different processing conditions such as pressure (from 80 up to 150 bar) and temperature (45 and 55°C) were studied and the effect on the morphological features of the scaffolds was evaluated by scanning electron microscopy and micro-computed tomography. The mechanical properties of the SPCL scaffolds prepared were also studied. Additionally, in this work, the in vitro biological performance of the scaffolds was studied. Cell adhesion and morphology, viability and proliferation was assessed and the results suggest that the materials prepared are allow cell attachment and promote cell proliferation having thus potential to be used in some for biomedical applications.Ana Rita C. Duarte is grateful for financial support from Fundacao para a Ciencia e Tecnologia through the grant SFRH/BPD/34994/2007

Associations between vaccination and antimicrobial consumption in Danish pig herds, 2013

Antimicrobial agents are being used in modern swine production worldwide, generating concern in regards to the development of antimicrobial resistance. Identifying efficient alternatives has therefore become a subject of interest. The aim of this study was to explore the impact of routinely used vaccination as an alternative to antimicrobial consumption in weaner pig herds. The hypothesis was that herds with increased use of vaccination would have a lower antimicrobial consumption. Data were obtained from the Danish VetStat database in which prescriptions of medication for livestock are recorded as well as the Danish Central Husbandry Register. All Danish one-site pig herds, active in year 2013, with \u3e50 sows and \u3e200 weaners were selected for the study. Initially, data were analysed using a univariable model, and secondly a multivariable linear regression model was applied. The analyses included use of three different vaccines against Porcine Circovirus Type 2 (PCV2), Mycoplasma hyopneumoniae (M_HYO) and Lawsonia intracellularis (LAW), respectively, as well as annual production measured as number of weaners produced in a year. The outcome was the average antimicrobial consumption measured in animal daily does (ADD) per weaner pig. Out of the 1,513 herds selected for the study, 1,415 herds had antimicrobials prescribed for gastrointestinal disorders, and 836 for respiratory disorders. PCV2 vaccine was used in 880 herds, M_HYO vaccine in 787 and LAW vaccine was the least used, with 115 herds using it. The results suggested that antimicrobials to some extent were being used for other disease categories than those officially prescribed by the veterinarians. On average, herds using the different combinations of vaccines had higher use of antimicrobials than herds not using the vaccines – probably as a result of health problems in the herds existing prior to the initiation of vaccine use. Information about vaccination protocols, health status, biosecurity, and management practices was not available limiting the ability to assess causality

Gelatin porous scaffolds fabricated using a modified gas foaming technique: Characterisation and cytotoxicity assessment

The current study presents an effective and simple strategy to obtain stable porous scaffolds from gelatin via a gas foaming method. The technique exploits the intrinsic foaming ability of gelatin in the presence of CO2 to obtain a porous structure stabilised with glutaraldehyde. The produced scaffolds were characterised using physical and mechanical characterisation methods. The results showed that gas foaming may allow the tailoring of the 3-dimensional structure of the scaffolds with an interconnected porous structure. To assess the effectiveness of the preparation method in mitigating the potential cytotoxicity risk of using glutaraldehyde as a crosslinker, direct and in-direct cytotoxicity assays were performed at different concentrations of glutaraldehyde. The results indicate the potential of the gas foaming method, in the preparation of viable tissue engineering scaffolds