Influência dos métodos de ensaio nas características de argamassas de cal aérea e hidráulica

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Civil – Reabilitação de Edifícios

Experimental study on polyester based concretes filled with glass fibre reinforced plastic recyclates – a contribution to composite materials sustainability

The development and applications of thermoset polymeric composites, namely fibre reinforced plastics (FRP), have shifted in the last decades more and more into the mass market [1]. Despite of all advantages associated to FRP based products, the increasing production and consume also lead to an increasing amount of FRP wastes, either end-of-lifecycle products, or scrap and by-products generated by the manufacturing process itself. Whereas thermoplastic FRPs can be easily recycled, by remelting and remoulding, recyclability of thermosetting FRPs constitutes a more difficult task due to cross-linked nature of resin matrix. To date, most of the thermoset based FRP waste is being incinerated or landfilled, leading to negative environmental impacts and supplementary added costs to FRP producers and suppliers. This actual framework is putting increasing pressure on the industry to address the options available for FRP waste management, being an important driver for applied research undertaken cost efficient recycling methods. [1-2]. In spite of this, research on recycling solutions for thermoset composites is still at an elementary stage. Thermal and/or chemical recycling processes, with partial fibre recovering, have been investigated mostly for carbon fibre reinforced plastics (CFRP) due to inherent value of carbon fibre reinforcement; whereas for glass fibre reinforced plastics (GFRP), mechanical recycling, by means of milling and grinding processes, has been considered a more viable recycling method [1-2]. Though, at the moment, few solutions in the reuse of mechanically-recycled GFRP composites into valueadded products are being explored. Aiming filling this gap, in this study, a new waste management solution for thermoset GFRP based products was assessed. The mechanical recycling approach, with reduction of GFRP waste to powdered and fibrous materials was applied, and the potential added value of obtained recyclates was experimentally investigated as raw material for polyester based mortars. The use of a cementless concrete as host material for GFRP recyclates, instead of a conventional Portland cement based concrete, presents an important asset in avoiding the eventual incompatibility problems arisen from alkalis silica reaction between glass fibres and cementious binder matrix. Additionally, due to hermetic nature of resin binder, polymer based concretes present greater ability for incorporating recycled waste products [3]. Under this scope, different GFRP waste admixed polymer mortar (PM) formulations were analyzed varying the size grading and content of GFRP powder and fibre mix waste. Added value of potential recycling solution was assessed by means of flexural and compressive loading capacities of modified mortars with regard to waste-free polymer mortars.

Hydraulic binders

Hydraulic binders play a vital role in the economic and social development because they are essential components of concrete, the most widely used construction material. Nowadays, Portland cement is the most predominantly used hydraulic binder due to its properties and widespread availability. Cement manufacture consumes large amount of non-renewable raw materials and energy, and it is a carbon-intensive process. Many efforts are, therefore, being undertaken towards the developing “greener” hydraulic binders. Concomitantly, binders must also correspond to market demand in terms of performance and aesthetic as well as fulfill mandatory regulations. In order to pursue these goals, different approaches have been followed including the improvement of the cement manufacturing process, production of blended cements, and testing innovative hydraulic binders with a different chemistry. This chapter presents a brief history of hydraulic binder’s discovery and use as well as the environmental and economic context of cement industry. It, then, describes the chemistry and properties of currently most used hydraulic binders—common cements and hydraulic limes—and that of the more promising binders for future applications, namely special Portland cements, aluminous cements, calcium sulfoaluminate cements, and alkali-activated cements.

Avaliação da evolução das características de argamassas de cal aérea com diferentes teores de metacaulino sujeitas a ambientes de diferente humidade relativa

Dissertação para obtenção do grau Mestre em Engenharia Civil – Perfil de Construção

Analysis of proteins from membrane and soluble fractions of Giardia duodenalis trophozoites of two Brazilian axenic strains

In the present study, we have analyzed by sodium docecyl sulphate - polyacrilamide gel electrophoresis (SDS-PAGE), immunoblotting and Concanavalin A blotting (Con A blotting) proteins of membrane fractions and soluble fractions obtained from Giardia duodenalis trophozoites of two axenic strains isolated in Brazil from a symptomatic (BTU-11) and an asymptomatic patient (BTU-10), as compared to the reference strain Portland 1. Both Brazilian strains showed a complex and homogeneous electrophoretic pattern of proteins, but some differences could be observed. Several glycoproteins were detected, particularly the proteins of 81, 72, 59 kDa and the protein of 62 kDa in the membrane proteins and cytosol, respectively. Many antigenic components were revealed by anti-Giardia rabbit IgG antibodies in the immunoblotting analysis. Among these components, the membrane protein of 32 kDa and the cytosol protein of 30 kDa could be related to giardin, as previously demonstrated.

Clonal types and antimicrobial resistance profiles of methicillin-resistant Staphylococcus aureus isolates from hospitals in south Brazil

In the present study were evaluated the DNA macrorestriction profile and SCCmec types for nine multi-resistant MRSA selected. Also antimicrobial susceptibility testing by disk diffusion method was evaluated for 68 MRSA isolates against 12 antimicrobial agents. The isolates were recovered from blood culture collected from hospitalized patients in three hospitals of Porto Alegre, Brazil. PFGE and PCR for mecA and SCCmec I, II, III, IV types genes were done on selected nine isolates with susceptibility only to vancomycin, teicoplanin and linezolid. Two clone profiles, with five subtypes, were demonstrated among multi-resistant MRSA analyzed. Eight isolates showed harbor SCCmec type III and one isolate was not typeable. The knowledge of SCCmec type, clone and antimicrobial profiles among S. aureus is essential mainly to prevention and control of dissemination of the antimicrobial resistance.

A contribuição das bombas de efluxo QacA e Smr para a multirresistência em Staphylococcus aureus

RESUMO: O efluxo de compostos antimicrobianos é um mecanismo importante na multirresistência em bactérias. Bombas de efluxo codificadas em plasmídeos, como a QacA e a Smr, estão implicadas na susceptibilidade reduzida a biocidas, geralmente utilizados na prevenção e controlo de infecções nosocomiais, incluindo as causadas por estirpes de Staphylococcus aureus resistentes à meticilina (MRSA). Neste trabalho pretendeu-se avaliar a relevância de QacA e Smr no perfil de susceptibilidade dos isolados clínicos MRSA SM39 e SM52, que transportam os plasmídeos pSM39 e pSM52 com os determinantes qacA e smr, respectivamente. A actividade de efluxo das estirpes SM39 e SM39 curada (sem pSM39) e das estirpes SM52 e RN4220:pSM52 (estirpe susceptível RN4220 transformada com pSM52) foi caracterizada por: (1) determinação da concentração mínima inibitória (CMI) de biocidas, corantes e antibióticos, na ausência e presença dos inibidores de efluxo tioridazina, clorpromazina, verapamil e reserpina; e (2) fluorometria em tempo-real. A determinação de CMIs demonstrou que a actividade de efluxo mediada por QacA e Smr está envolvida na susceptibilidade reduzida aos biocidas e corantes testados, que incluíram o brometo de hexadeciltrimetilamónio, a cetrimida, o cloreto de benzalcónio, a berberina, o cloreto de dequalínio, a pentamidina e o brometo de etídeo. Os ensaios fluorométricos confirmaram a elevada actividade de efluxo presente nas estirpes com os genes qacA ou smr. A determinação de CMIs para antibióticos β-lactâmicos em conjunto com o teste da nitrocefina revelou a presença simultânea do gene qacA e de uma β-lactamase no plasmídeo pSM39. Este trabalho evidencia a importância das bombas de efluxo QacA e Smr na resistência a biocidas em estirpes MRSA e na sobrevivência destas estirpes em ambiente hospitalar e na comunidade, para além de destacar a questão da potencial co-resistência entre biocidas e antibióticos.--------------- ABSTRACT: Drug efflux has become an important cause of multidrug resistance (MDR) in bacteria. Plasmid-encoded MDR efflux pumps, such as QacA and Smr, are implicated in reduced susceptibility to biocides, generally used in the prevention and control of nosocomial infections, including the ones caused by methicillin-resistant Staphylococcus aureus (MRSA). In this work, we aimed to evaluate the relevance of QacA and Smr to the susceptibility profile of the clinical MRSA isolates SM39 and SM52, which harbor the plasmids pSM39 and pSM52 that carry the determinants qacA and smr, respectively. Efflux activity of strain SM39 and its plasmid-free counterpart, SM39 cured, SM52 and RN4220:pSM52 (susceptible strain RN4220 transformed with pSM52) was characterized by: (1) determination of minimum inhibitory concentration (MIC) of biocides, dyes and antibiotics, in the absence and presence of the efflux inhibitors thioridazine, chlorpromazine, verapamil and reserpine; and (2) real-time fluorometry. MIC determination showed that QacA and Smr mediated efflux was involved in the reduced susceptibility profile to the biocides and dyes tested, which included hexadecyltrymethylammonium bromide, cetrimide, benzalkonium chloride, berberine, dequalinium chloride, pentamidine and ethidium bromide. Fluorometric assays confirmed the higher efflux activity present in strains harboring qacA or smr genes. Moreover, MIC determination for β-lactam antibiotics together with the nitrocefin test confirmed the presence of a β-lactamase in the plasmid carried by SM39 strain, pSM39. This work highlights the relevance of QacA and Smr to the biocide resistance in MRSA strains, and consequently to their survival and maintenance in the hospital environment and in the community. Furthermore, the presence of a β-lactamase and qacA determinants in the the same plasmid reinforces the question of the potencial biocide/antibiotic co-resistance in MRSA strains.

Cryptococcus neoformans isolation from swallow (Hirundo rustica) excreta in Iran

Cryptococcus neoformans is an encapsulated yeast that can cause cryptococcosis, a life-threatening infection that mainly occurs in immunocompromised patients. The major environmental sources of C. neoformans have been shown to be soil contaminated with avian droppings. In the present study, we evaluated the isolation of C. neoformans from swallow (Hirundo rustica) excreta in two northern cities of Iran. Ninety-seven swallow droppings were evaluated and 498 yeast-like colonies were isolated and identified as Rhodotorula spp. (62.8%), Candida spp. (28.5%)and C. neoformans (8.7%). Cryptococcus neoformans was isolated from 5/97 (5.2%) of collected samples. Min-Max colony forming units (CFU) per one gram for the positive samples were 3-10 C. neoformans colonies. The total mean CFU per one gram for the positive samples was 4.8. The results of this study demonstrate that excreta of swallow may harbor different species of potentially pathogenic yeasts, mainly C. neoformans, and may be capable of disseminating these fungi in the environment.

ANTIMICROBIAL DRUG RESISTANCE IN STRAINS OF Escherichia coli ISOLATED FROM FOOD SOURCES

A variety of foods and environmental sources harbor bacteria that are resistant to one or more antimicrobial drugs used in medicine and agriculture. Antibiotic resistance in Escherichia coli is of particular concern because it is the most common Gram-negative pathogen in humans. Hence this study was conducted to determine the antibiotic sensitivity pattern of E. coli isolated from different types of food items collected randomly from twelve localities of Hyderabad, India. A total of 150 samples comprising; vegetable salad, raw egg-surface, raw chicken, unpasteurized milk, and raw meat were processed microbiologically to isolate E. coli and to study their antibiotic susceptibility pattern by the Kirby-Bauer method. The highest percentages of drug resistance in isolates of E. coli were detected from raw chicken (23.3%) followed by vegetable salad (20%), raw meat (13.3%), raw egg-surface (10%) and unpasteurized milk (6.7%). The overall incidence of drug resistant E. coli was 14.7%. A total of six (4%) Extended Spectrum β-Lactamase (ESBL) producers were detected, two each from vegetable salads and raw chicken, and one each from raw egg-surface and raw meat. Multidrug resistant strains of E. coli are a matter of concern as resistance genes are easily transferable to other strains. Pathogen cycling through food is very common and might pose a potential health risk to the consumer. Therefore, in order to avoid this, good hygienic practices are necessary in the abattoirs to prevent contamination of cattle and poultry products with intestinal content as well as forbidding the use of untreated sewage in irrigating vegetables.

Estudo de Argamassas com Cinza de Casca de Amêndoa

Perante o elevado consumo de materiais naturais no processo e produtos na área da construção civil, o reaproveitamento de resíduos é uma das soluções a ser estudada. As cinzas agroindustriais têm lugar de destaque entre estes resíduos, pois têm a possibilidade de aplicação em materiais cimentícios, reduzindo assim o consumo de cimento de Portland. O presente estudo debruça-se sobre a substituição parcial (1,5% e 5%) de cimento de Portland por cinzas de casca de amêndoa. Realizaram-se provetes com diferentes tipos de argamassas: (i) uma de controlo sem substituição de cimento (ARF); (ii) uma com 1,5% de substituição parcial de cimento por cinzas de casca de amêndoa (CCA 1,5%); (iii) e uma com 5% de substituição parcial de cimento por cinza de casca de amêndoa (CCA 5%). Executaram-se ensaios para resistências mecânicas aos 3, 7, 14, 28 e 41 dias de idade. A nível químico pode-se concluir que esta cinza de casca de amêndoa não apresentou qualquer potencial pozolânico. A trabalhabilidade na generalidade diminui ligeiramente, contendo cinza de casca de amêndoa, mas ainda assim considerando-se de fácil manuseamento. Em relação às resistências mecânicas, pode-se concluir que o ideal é a substituição parcial de cimento com 1,5%, pois as resistências diminuem com o uso de uma maior percentagem de substituição, ou seja, o ideal é substituir em pequenas percentagens. Com os dados obtidos, conclui-se que as cinzas testadas não apresentam características necessárias para serem consideradas pozolanas e se será viável a sua utilização mesmo como filer.

New spectroscopic and electrochemical insights on a class I superoxide reductase: evidence for an intramolecular electron-transfer pathway

Biochem. J. (2011) 438,485–494 doi:10.1042/BJ20110836

Caracterização de argamassas de cal hidráulica natural NHL 3.5 de fabrico nacional

Dissertação para obtenção do Grau de Mestre em Engenharia Civil – Perfil de Construção

The compatibility of earth-based repair mortars with rammed earth substrates

3rd Historic Mortars Conference, 11-14 September 2013, Glasgow, Scotland

Earth-based repair mortars: experimental analysis with different binders and natural fibers

RESTAPIA 2012 - Int. Conf. on Rammed Earth Conservation, Valencia, 21-23 June 2012

Caracterização de argamassas pré-doseadas de fabrico nacional

PATORREB 2006 - 2º Encontro sobre Patologia e Reabilitação de Edifícios, FEUP, Porto, Março 2006, p. 381-390