Identification of Segments of European Banks with a Latent Class Frontier Model

This paper analyses technical efficiency of European banks over the period 1996-2003 with unbalanced panel data techniques. A latent class frontier model is used which allows the identification of different segments in the production frontier. We find that there are three statistically significant segments in the sample. Therefore, we conclude that no common banking policy can be effective for all the banks included in the sample, and that banking policies by segments are required instead.European banking, latent class frontier model, technical efficiency

Nanoparticles based on novel carbohydrate-functionalized polymers

PD/BD/109680/2015 UID/QUI/50006/2019 POCI-01-0145-FEDER-007265Polymeric nanoparticles can be used for drug delivery systems in healthcare. For this purpose poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) offer an excellent polymeric matrix. In this work, PLGA and PEG polymers were functionalized with coumarin and carbohydrate moieties such as thymidine, glucose, galactose, and mannose that have high biological specificities. Using a single oil in water emulsion methodology, functionalized PLGA nanoparticles were prepared having a smooth surface and sizes ranging between 114-289 nm, a low polydispersity index and a zeta potential from -28.2 to -56.0mV. However, for the corresponding PEG derivatives the polymers obtained were produced in the form of films due to the small size of the hydrophobic core.publishersversionpublishe

Gas-Phase Lubrication of ta-C by Glycerol and Hydrogen Peroxide. Experimental and Computer Modeling

Tetrahedrally coordinated hydrogen-free amorphous diamond-like carbon coating (denoted as ta-C) presents ultralow friction under boundary lubrication conditions at 80 °C in presence of OH-containing molecules. To understand the mechanism of ultralow friction, we performed gas-phase lubrication experiments followed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) analyses and this using two simple molecules: deuterated glycerol and hydrogen peroxide. The experiments were complemented by computer simulations using the ReaxFF reactive force field. These simulations suggest a ta-C surface rich in sp^2 carbon with some reactive sp^1 carbon atoms, in agreement with previous energy filtered transmission electron microscopy (EFTEM) results. Sliding simulations show that the carbon surface atoms react with glycerol and hydrogen peroxide to form OH-termination. Moreover, the hydroxylation is then followed by the chemical dissociation of some of the glycerol molecules leading to the formation of water. This is in agreement with the secondary ion mass spectrometry (SIMS) analyses and mass spectrometer results obtained with gas-phase lubrication experiments with the same molecules. Both experimental and computer simulations strongly suggest that the hydroxylation of the carbon surface is at the origin of ultralow friction together with the formation of water-rich film in the sliding interface

Durabilidade de argamassas de base cimentícia reforçadas com fibras sintéticas

O presente artigo apresenta os resultados obtidos num programa experimental de caracterização de três argamassas de matriz cimentícia reforçadas com diferente tipo de fibras, nomeadamente, fibras de poliacrilonitrila (PAN), vidro (GF), polipropileno (PP) e de álcool polivinílico (PVA). A avaliação do desempenho das fibras como reforço efetivo de materiais de matriz cimentícia, foi realizada com ensaios de avaliação das propriedades reológicas, mecânicas (compressão e flexão) e de durabilidade (absorção de água por capilaridade e permeabilidade ao ar e à água). De modo a comparar e analisar os resultados obtidos, foram também realizados os mesmos ensaios com uma argamassa comercial de base cimentícia. Os ensaios são descritos e os principais resultados obtidos são apresentados e discutidos.Esta investigação foi realizada no âmbito do projeto InoTec - Material inovador de ultra elevada ductilidade para a reabilitação do património construído, promovido pela Empresa CiviTest e pela Universidade do Minho e financiado pelo COMPETE / QREN / FEDER (NORTE-07-0202 FEDER-023024). O primeiro autor agradece a bolsa de investigação atribuída ao abrigo deste projeto. Um especial agradecimento à empresa Owens Corning pelo fornecimento das fibras de vidro, à Exporplas pelas fibras de polipropileno, à Sika pelo superplastificante, à Secil pelo cimento, à CHRYSO pelo VMA e à S&P Clever Reinforcement Ibérica pelo fornecimento da argamassa comercial

Durabilidade do betão auto-compactável reforçado com fibras de aço

A durabilidade é uma das características mais importantes que o betão deve possuir devido à sua fundamental incidência na vida útil das estruturas. Para os betões convencionais, sem adição de fibras de aço, existem indicadores de durabilidade que são já de utilização corrente. No entanto, para o betão auto-compactável reforçado com fibras de aço (BACRFA) a investigação relacionada com a durabilidade ainda é escassa, nomeadamente os aspetos relacionados com a resistência à corrosão das fibras. Neste seguimento, desenvolveu-se um trabalho experimental com provetes de BACRFA e provetes de betão auto-compactável (BAC) sem fibras, com o objetivo de caracterizar o comportamento mecânico (módulo de elasticidade, resistência à compressão e à flexão) e avaliar parâmetros indicadores de durabilidade (absorção de água por imersão e por capilaridade, permeabilidade ao ar, resistividade elétrica, difusão de cloretos por migração em regime não estacionário e resistência à carbonatação). Os resultados obtidos para os diferentes betões em estudo são apresentados e analisados.

M.S.W. bottom ash : mechanical characterization for road pavement purposes

Neste trabalho são estudadas as propriedades mecânicas, tais como a rigidez e a resistência, de escórias provenientes da incineração de resíduos sólidos urbanos na incineradora da Valorsul, S.A.. Pretende-se avaliar, sob o ponto de vista geotécnico, a viabilidade de utilização deste material alternativo nas camadas estruturais de pavimentos rodoviários. Neste sentido, são apresentados resultados provenientes dos seguintes ensaios laboratoriais: análise granulométrica; ensaios C.B.R. e ensaio triaxial estático consolidado não drenado com medição das pressões intersticiais. Este estudo pretende contribuir para a valorização das escórias, cuja produção em Portugal, para 2006, se estima em cerca de 293 000 toneladas por ano. Para além de permitir reduzir a quantidade de resíduos a encaminhar para deposição final, o estudo também implica a diminuição da exploração de agregados naturais.In this work the mechanical properties are studied, such as the stiffness and the strength, of bottom ashes from the incineration of municipal solid wastes in the Valorsul, S.A. incinerator. It is intended to evaluate, under the geotechnical point of view, the viability of using this alternative material in the structural layers of road pavements. In this direction, they are presented results proceeding from the following laboratory tests: grain sized analysis; C.B.R. test and undrained consolidated static triaxial test with measurement of the pore water pressures. This study intends to promote MSW bottom ashes, whose production for 2006, in Portugal, is estimated around 293 000 tons per year. Besides allowing reducing the amount of residues to final deposition, the study also implies the reduction of natural aggregate exploration

Systematic evaluation of the antioxidant potential of different parts of Foeniculum vulgare Mill. from Portugal

Fennel (Foeniculum vulgare Mill.) is a widespread perennial umbeliferous (Apiaceae) herb, traditionally used for medicinal purposes and human consumption. It is highly recommended for diabetes, bronchitis and chronic coughs, and for the treatment of kidney stones; some of those chronic diseases are related to the production of radical species involved in the oxidative stress. Therefore, the antioxidant potential of this herb might explain some of their empirical uses in folk medicine. This is the first time that a systematic study on different parts of fennel is performed, in order to understand differences in the antioxidant potential of shoots, leaves, steams, and inflorescences, particularly related to their composition in antioxidant compounds such as vitamins (ascorbic acid and tocopherols) and phenolics. The shoots seems to have the highest radical-scavenging activity and lipid peroxidation inhibition capacity (EC50 values < 1.4 mg/ml), which is in agreement with the highest content in phenolics (65.85 ± 0.74 mg/g) and ascorbic acid (570.89 ± 0.01 lg/g) found in this part. The shoots also revealed high concentration of tocopherols (34.54 ± 1.28 lg/g) and were the only part with flavonoids

Lamiaceae often used in Portuguese folk medicine as a source of powerful antioxidants: vitamins and phenolics

Three Lamiaceae often used in Portuguese folk medicine: Ground ivy (Glechoma hederaceae L.), oregano (Origanum vulgare subsp. virens (Hoffmanns. & Link) Ietswaart) and mastic thyme (Thymus mastichina L.), revealed to be good sources of powerful antioxidants such as vitamins (ascorbic acid and tocopherols) and phenolics. The HPLC methodology developed for tocopherols analysis proved to be, after validation assays, sensitive and accurate. Ground ivy showed the highest levels of vitamins: ascorbic acid (168 2 mg/g dry weight) and tocopherols (3692 57 mg/g dry weight). The phenolics extraction was optimized using mastic tyme, and different conditions (water and ethanol:water 50% v/v, 30 min at 25 C and boiling temperature; ethanol and methanol, 24 h at 25 C). The best methodology (25 C, 50 ml of methanol, 24 h) was further applied to the other Lamiaceae. Oregano proved to have the highest radical scavenging and lipid peroxidation inhibition capacity. Particularly, the very low EC50 value (0.01 mg/ml) obtained for TBARS inhibition in brain homogenates is very promising, considering that brain is highly sensitive to oxidative damage. Significantly negative linear correlations were observed between phenolics, including flavonoids, and antioxidant activity EC50 values of the three Lamiaceae

An experimental investigation on the post-cracking behaviour of Recycled Steel Fibre Reinforced Concrete

Steel fibres resulting from the industry of tyre recycling can be efficiently employed for the reinforcement of concrete structures. Recycled Steel Fibre Reinforced Concrete (RSFRC) is a promising candidate with technical, environmental and economic benefits for the development of ductile, high strength and durable constructive systems, as it is required for breakwater elements used on the protection of coastal zones. For assessing the potentialities of recycled steel fibres (RSF) as concrete reinforcement, an experimental program was performed in the present work by comparing the following properties of concrete reinforced with industrial steel fibres (ISF) and with RSF: compressive strength, modulus of elasticity, flexural strength, flexural toughness and indirect tensile strength. Under chloride attack, the durability performance of RSFRC requires the assessment of its corrosion resistance. To evaluate the corrosion effects on the post-cracking response of RSFRC, double edge wedge splitting tensile tests were conducted in RSFRC specimens previously exposed to aggressive chloride environment. The obtained results demonstrate that, for the adopted industrial and recycled fibres, the last ones had not inferior post-cracking strengthening performance than the first ones. The corrosion action caused a slight decrease of the average post-cracking tensile strength of the RSFRC. The small percentage of rubber attached to RSF surface had a negligible effect in the corrosion resistance of RSFRC.FCT through PTDC/ECMEST/2635/2014 project, as well as the collaboration of CiviTest Company in the production of concretes. The first author would like to thank the FCT for the financial support through the Research Grant PD/BD/113638/2015. The supplying of RSF and ISF from Twincon and Maccaferri Companie

Influence of the chloride attack on the post-cracking behavior of Recycled Steel Fiber Reinforced Concrete

The main purpose of the present work is to study the mechanical behavior and durability performance of recycled steel fiber reinforced concrete (RSFRC) under a chloride environment. To this end, the effect of chloride attack on the load-carrying capacity of pre-cracked RSFRC round panels is investigated by performing round panel tests supported on three points (RPT-3ps), considering the influence of the crack width and the fiber distribution/orientation profile. In addition, the influence of the adopted chloride exposure conditions on the post-cracking constitutive laws of the developed RSFRC is also assessed by performing numerical simulations for the prediction of the long-term performance of RSFRC under these aggressive conditions. The tensile stress–crack width relationship of RSFRC is derived by performing an inverse analysis with the RPT-3ps results. The obtained experimental and numerical results show a negligible effect of the chloride attack on the post-cracking behavior of RSFRC for the chloride exposure conditions and pre-crack width levels adopted in this study.This research was funded by C.F. research grant PD/BD/113638/2015 provided by Fundação para a Ciência e a Tecnologia (FCT) through the Doctoral Program in Eco Construction and Rehabilitation–EcoCoRe, and J.B. through the project ICoSyTec (POCI-01-0145-FEDER-027990) financed by FCT and co-funded by FEDER through Operational Competitiveness and Internationalization Programme (POCI)