Three-dimensional layer-by-layer strategies for tissue engineering and nanomedicine

Layer-by-layer (LbL) is a self-assembly-driven surface modification strategy that allows the construction of nanostructured films onto substrates of any geometry, from simple bidimensional surfaces to more complex three-dimensional porous scaffolds. The principle behind LbL lies in the existence of multiple intermolecular interactions, such as electrostatic contacts, hydrophobic interactions, and hydrogen bonding, where the cooperative effects of multipoint attractions play the most important role. It is a technique that offers ease of preparation, versatility, fine control over the materials structure and robustness under physiological conditions. Although LbL has been mostly limited to the modification of planar surfaces, its potential lies in the capability to be extrapolated to 3D structures and coat increasingly complex geometries. Currently trending is the use of spherical templates – sacrificial or non-sacrificial – for applications in Nanomedicine, such as the construction of drug carriers or for the encapsulation of cells. The nanostructured nature of multilayered coatings makes it possible to build containers which permeability to molecules may be tuned simply by varying the number of involving layers or the class of materials involved. This way, in drug delivery it would be possible to construct structures in which the permeability of a drug to the exterior could be adjusted to a specific application or therapy, such as non-systemic approaches to cancer. In cell encapsulation, multilayer films could be employed to grant immune protection to the encapsulated biological materials, such as pancreatic islet cells, and enhanced control of both transport properties and surface physicochemical characteristics. Therefore, LbL presents an ambitious step in the development of effective encapsulating barriers for both active agents and cells

Nanostructured multilayers in the production of new devices for biomedical applications

Surface engineering is of the utmost significance in the conception of devices with an improved biological performance. By addressing physical and chemical features of interfaces, it has been possible to develop patterned and stimuli-responsive devices with tunable wettability and protein/cell adhesion properties with application in biomedicine and tissue engineering. While several surface engineering approaches exist, there is an increasing emphasis to non-harmful and versatile techniques to modify polymeric substrates: the sequential adsorption of proteins and polysaccharides, known as layer-by-layer (LbL) adsorption, is one of the most promising today. It is a simple and versatile technique where the cooperative effects of multipoint attractions allowing to produce robust coatings, even in substrates with complex geometries. Because it discards the need of organic and harmful solvents, it is an attractive technique for tissue engineering applications. Multilayer systems have already been proposed for different biomedical applications, including for biomimetic composite-like coatings, surfaces with smart properties, and to manipulate the adhesion and proliferation of cells

Avaliação do custo vs benefício na introdução de medidas de sustentabilidade na reabilitação de edifícios antigos – estudo de caso

Tendo por base os novos desafios com que o sector da construção, nomeadamente este artigo tem como objetivo a avaliação dos custos económicos e dos benefícios em termos energéticos e de sustentabilidade decorrentes da implementação de três cenários de reabilitação (básica, energética e sustentável) num edifício unifamiliar situado no centro histórico de Viana do Castelo

Reabilitação sustentável de edifícios antigos : contribuição para os edifícios de balanço energético nulo (nZEB) e otimização do nível de sustentabilidade

O aumento do consumo dos recursos energéticos não renováveis tornou-se num problema de grande relevo, tanto em termos económicos como ambientais. Para minimizar este problema foi publicada em 2002 uma diretiva europeia, a EPBD, cuja reformulação em 2010 obriga a que todos os edifícios novos e grandes reabilitações sejam caracterizados, a partir de 2020, por um balanço energético quase nulo. Em Portugal, a transposição desta diretiva deu-se através da implementação dos Decreto-Lei n.º 78/2006 (SCE), Decreto-Lei n.º 79/2006 (RSECE) e Decreto-Lei n.º 80/2006 (RCCTE). Contudo, apesar de estes regulamentos terem contribuído para uma melhoria das condições do parque habitacional português, não foi verificada uma melhoria significativa, uma vez que a maioria do edificado é anterior à implementação destes. Torna-se assim indispensável pensar na reabilitação como estratégia fundamental para reduzir as necessidades energéticas no país. No presente trabalho é efetuada a análise energética e de sustentabilidade de um caso de estudo através de três cenários de reabilitação diferentes, sendo eles, Reabilitação Básica, Reabilitação Energética e Reabilitação Sustentável. A análise energética foi realizada segundo o RCCTE com o apoio da ferramenta informática CYPE e a avaliação de sustentabilidade foi efetuada com recurso à metodologia SBToolPT-H

Nanostructured thin coatings from chitosan and an elastin-like recombinamer with acute stimuli-responsive behavior

Publicado em: Materials Science Forum, vols. 730-732; Online available since 2012/Nov/12In the present work, chitosan (CHI) and elastin-like recombinamers (ELRs) were used to conceive nanostructured thin films driven by sequential electrostatic layer-by-layer (LbL), a simple and versatile technique that discards the use of harmful reagents. Two similar ELRs were engineered to contain negatively charged aminoacids and organized and a single monoblock or a triblock. The buildup of the films was monitored in real time using a quartz-crystal microbalance with dissipation monitoring (QCM-D). Wettability transitions were observed from a moderate hydrophobic surface to an extremely wettable upon increasing the temperature to 50 ºC, accompanied by topography changes at the nanoscale as assessed by atomic force microscopy (AFM). Furthermore, the dependence on time for the surface molecular rearrangement was studied for the films with each ELR. The potential of this technology may stimulate the development of devices and biomaterials for biomedical applications in the near future, such as surfaces with tunable and patterned cell adhesion, while the use of ELRs will allow developing polypeptides with biological significance.The authors acknowledge the financial support through Fundação para a Ciência e Tecnologia (FCT, PhD grant SFRH/BD/61126/2009, ‘‘Junta de Castilla y Leon’’ (VA034A09), the MICINN (MAT 2009-14195-C03-03, ACI2009-0890, IT2009-0089, MAT2010-15310, and MAT2010- 15982), the CIBER-BBN and the ‘‘Network Center of Regenerative Medicine and Cellular Therapy of Castilla y León’’.MICINNFundação para a Ciência e a Tecnologia (FCT)Junta de Castilla y LeónCIBER-BBNNetwork Center of Regenerative Medicine and Cellular Therapy of Castilla y Leó

Evolution of body mass índex of women undergoing bariatric surgery in the pre- and pos-operative period: a retrospective study

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Weighing-in-motion wireless system for sustainable railway transport

Railway transport is well known as one of the safest and most energy-efficient transport modes, thus favoring its strengthening as part of a sustainable transport system. Yet, the track service life and the quality of the ride on a railway are dependent upon different factors, which can be assessed by a diverse set of technology based systems. In this context, this paper presents the EVO4Rail project that seeks to design, develop and implement a wireless monitoring system for weighing-in-motion and detecting faulty wheels in railway vehicles, positively impacting railway operation, maintenance and management, ultimately aiming at a sustainable rail transport.info:eu-repo/semantics/publishedVersio

Secagens convectivas de pêra S. Bartolomeu em túnel.

Foram realizadas em Agosto dos anos de 2007 e 2008 secagens de pêra São Bartolomeu em túnel, com circulação de ar forçada. Estes ensaios foram realizados, como alternativa às técnicas convencionais de secagem solar, em regime contínuo. Nos anos de 2007 e 2008 foram utilizadas temperaturas de sacagem de 40ºC. Em 2007 foi realizada também uma secagem a 30ºC. Foram utilizados diversos caudais de ar nos dois anos. Os resultados obtidos permitiram constatar que a temperatura desempenha um papel fulcral ao nível da velocidade de secagem, quando comparada com o factor velocidade do ar. As secagens a 40ºC revelaram-se vantajosas ao nível da rapidez, aliada a uma maior segurança alimentar do processo, quando comparadas com a mesma operação a 30ºC. As secagens convectivas efectuadas em regime contínuo mostraram ser uma alternativa a considerar relativamente à secagem tradicional de pêra São Bartolomeu, por permitir uma maior rapidez de secagem e controlo do processo. Contudo a ausência de algumas características organolépticas, nomeadamente ao nível da coloração do produto final, apresenta-se como uma condicionante a ser minimizada