Avaliação do impacte ambiental de duas soluções estruturais diferentes associado à construção de uma habitação unifamiliar

Em Portugal, a aplicação nas estruturas de materiais naturais ainda corresponde apenas a solução construtiva pontual. Neste contexto, foram estudadas duas soluções estruturais para uma habitação unifamiliar sendo uma de betão armado, denominada aqui por solução tradicional, e outra de alvenaria de adobe e pavimentos de madeira, denominada por solução sustentável. Avaliou-se o impacto ambiental associado à produção e ao transporte dos materiais para ambas as soluções estudadas e concluiu-se, como era espectável, que o impacte ambiental associado a solução sustentável é significativamente menor

Estudo do ganho energético associado à construção de uma habitação unifamiliar com recurso a materiais naturais no contexto português

Em Portugal a indústria de construção habitacional tem recorrido essencialmente às estruturas de betão armado e de alvenaria de tijolo cerâmico. As estruturas metálicas, de madeira e de alvenaria de pedra têm tido expressão reduzida neste sector da construção e são muito pontuais as aplicações da terra crua como solução construtiva, desenvolvidas por técnicos e empresas particularmente interessadas nestes materiais. Por sua vez, tem havido uma crescente sensibilização de todos os agentes envolvidos no sector da construção civil para aspectos relacionados com o equilíbrio do meio ambiente e com a sustentabilidade neste sector. É neste contexto que este trabalho de investigação se insere, estudando soluções construtivas sustentáveis recorrendo ao uso de materiais de construção naturais. Para o efeito, foi estudada uma habitação unifamiliar com uma tipologia típica para duas soluções estruturais: uma estrutura porticada pilar-viga de betão armado e lajes aligeiradas pré-fabricadas (designada neste trabalho por solução tradicional); uma solução estrutural à base de materiais naturais (designada aqui por solução sustentável). A solução estrutural com recurso a materiais naturais estudada é definida por paredes resistentes de adobe e estrutura de madeira nos pavimentos e cobertura. Estas duas soluções estruturais são comparadas em termos de estimativas de custo, parâmetros de gasto energético e do teor de emissão de CO2 associados à produção dos materiais e à própria construção tendo-se verificado que a solução sustentável é mais vantajosa no que diz respeito a estes três aspectos

Advantages of using raw materials in low cost sustainable structural solutions for single-family buildings

In the last decades, the Portuguese housing building industry has been mainly fo-cused on the construction based on reinforced concrete framed structures and non-structural clay brick masonry for exterior and interior partition walls. Recently, this industry started to in-clude alternative structural materials, such as steel and timber. The earth based construction techniques and solutions still remains limited to individual cases, in which the owner and/or contractor have a particular concern and knowledge of these ecological solutions. Within this context was developed the present research work, in which a sustainable structural solution for a typical house using natural materials is proposed and studied. Two different structural solu-tions are defined, namely a reinforced concrete framed column-beam solution (designated by traditional solution) and a solution based on adobe masonry and timber structures for floors and roof (designated by sustainable solution). These two alternative structural solutions are then compared in terms of building costs, energy consumption and CO2 emissions. All the main as-pects related to the design of the sustainable solution, such as the design assumptions, structural models and behaviour parameters are described. Taking into account that the proposed sustain-able solution is uncommon in the Portuguese building context, the difficulties faced during the design are also pointed out and commented

Semiclassical approach to black hole absorption of electromagnetic radiation emitted by a rotating charge

We consider an electric charge, minimally coupled to the Maxwell field, rotating around a Schwarzschild black hole. We investigate how much of the radiation emitted from the swirling charge is absorbed by the black hole and show that most of the photons escape to infinity. For this purpose we use the Gupta-Bleuler quantization of the electromagnetic field in the modified Feynman gauge developed in the context of quantum field theory in Schwarzschild spacetime. We obtain that the two photon polarizations contribute quite differently to the emitted power. In addition, we discuss the accurateness of the results obtained in a full general relativistic approach in comparison with the ones obtained when the electric charge is assumed to be orbiting a massive object due to a Newtonian force.Comment: 8 pages (revtex), 8 figure

Quantitative evaluation of visual function 12 months after bilateral implantation of a diffractive trifocal IOL

PURPOSE: To quantitatively evaluate visual function 12 months after bilateral implantation of the Physiol FineVision® trifocal intraocular lens (IOL) and to compare these results with those obtained in the first postoperative month. METHODS: In this prospective case series, 20 eyes of 10 consecutive patients were included. Monocular and binocular, uncorrected and corrected visual acuities (distance, near, and intermediate) were measured. Metrovision® was used to test contrast sensitivity under static and dynamic conditions, both in photopic and low-mesopic settings. The same software was used for pupillometry and glare evaluation. Motion, achromatic, and chromatic contrast discrimination were tested using 2 innovative psychophysical tests. A complete ophthalmologic examination was performed preoperatively and at 1, 3, 6, and 12 months postoperatively. Psychophysical tests were performed 1 month after surgery and repeated 12 months postoperatively. RESULTS: Final distance uncorrected visual acuity (VA) was 0.00 ± 0.08 and distance corrected VA was 0.00 ± 0.05 logMAR. Distance corrected near VA was 0.00 ± 0.09 and distance corrected intermediate VA was 0.00 ± 0.06 logMAR. Glare testing, pupillometry, contrast sensitivity, motion, and chromatic and achromatic contrast discrimination did not differ significantly between the first and last visit (p>0.05) or when compared to an age-matched control group (p>0.05). CONCLUSIONS: The Physiol FineVision® trifocal IOL provided satisfactory full range of vision and quality of vision parameters 12 months after surgery. Visual acuity and psychophysical tests did not vary significantly between the first and last visit

Macrophage-derived neutrophil chemotactic factor is involved in the neutrophil recruitment inhibitory activity present in the supernatants of LPS-stimulated macrophages

In a previous study, we demonstrated the presence of a neutrophil recruitment inhibitory factor (NRIF) in the supernatants of LPS-stimulated macrophages. Recently, the purification of a 54 kDa protein, identified as the macrophage-derived neutrophil chemotactic factor (MNCF) was reported. Since NRIF and MNCF are obtained under the same conditions, and, since the intravenous administration of TNF-α and IL-8 inhibits neutrophil migration, we have investigated whether MNCF could be responsible for this inhibitory activity. After affinity chromatography of the macrophage supernatants on a D-galactose column, the inhibitory activity was recovered in both the unbound (D-gal−) and bound (D-gal+) fractions, with MNCF being found in the D-gal+ fraction. Further gel filtration of the latter on Superdex 75 yielded a single peak containing both activities. In a cytotoxicity assay, most of the TNF found in the crude supernatants was recovered in the D-gal− fraction. Furthermore, the incubation of the D-gal− fraction with anti-TNF-α plus anti-IL-8 antisera partially prevents its inhibitory effect on neutrophil migration, but had no effect on the D-gal+ activity. Overall, these results suggest that the D-gal− inhibitory effect is partially mediated by TNF-α and IL-8, and that MNCF accounts for the inhibition of neutrophil migration in vivo by the D-gal+ fraction