716 research outputs found

    Physicochemical, microbiological and antimicrobial properties of commercial honeys from Portugal

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    The present study aimed to characterize five commercial honeys available in the Portuguese market in respect to their floral origins, physicochemical parameters and microbial safety and commercial quality assessment. Pollen profile, colour, moisture content, ash, acidity, electrical conductivity, pH, reducing sugars, apparent sucrose and HMF were the parameters analysed in each honey sample. Aerobic mesophiles, moulds and yeasts, fecal coliforms and sulphite-reducing clostridia were the microbial contaminants of interest studied. The antimicrobial effect against four fermentative yeasts was determined. Concerning the physicochemical parameters, all honey samples were found to meet European Legislation (EC Directive 2001/110) for all parameters, except for HMF and apparent sucrose. Microbiologically, the commercial quality was considered good and all samples showed to be negative in respect to safety parameters. We also verified that the presence of honey differentially affected the growth of fermentative yeasts under study, depending on the type of yeast, but this growth was not significantly influenced by the type of honey used

    Determination of ascorbic acid and acetylsalicylic acid in commercial preparations using an electronic tongue

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    The electronic tongue is a multi-sensors system used to identify the basic standards of taste, such as sweet, salty, sour and bitter, at levels not detectable by humans. Although the main purpose of electronic tongue is the qualitative analysis, the quantitative analysis of substances in a liquid matrix is also possible, having been the subject of these preliminary studies the application of electronic tongue to pharmaceutical products. In this way, the aim of the current study was the quantitative analysis of ascorbic acid (AA) and acetylsalicylic acid (ASA) in several commercial preparations using an electronic tongue. For that, solutions of standard compounds or of commercial preparations contain ascorbic acid and acetylsalicylic acid were analizes by an electronic tongue. The obtained data were using to determine the concentrations of the solutions thought através do multiple linear regression method. The preliminary tests showed that it is possible to quantify the ascorbic acid in effervescent formulations of vitamin C, using the predictor model obtained by multiple linear regression. In the case of acetylsalicylic acid it was verified that the matrix of the analgesics or antipyretics drugs significantly affect the signs of the electronic tongue. The electronic tongue can be used determined ascorbic acid in effervescent formulations while it is necessary developed more selective sensors to acetylsalicylic acid in order to improve the predictive power of electronic tongue quantification of this compound

    Ferromagnetism without flat bands in thin armchair nanoribbons

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    Describing by a Hubbard type of model a thin armchair graphene ribbon in the armchair hexagon chain limit, one shows in exact terms, that even if the system does not have flat bands at all, at low concentration a mesoscopic sample can have ferromagnetic ground state, being metallic in the same time. The mechanism is connected to a common effect of correlations and confinement.Comment: 37 pages, 12 figures, in press at Eur. Phys. Jour.

    A apicultura em modo de produção biológico em Portugal - projeto BIOIMPACT

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    Apesar do potencial para a profissionalização e organização do setor, da aptidĂŁo florĂ­stica do paĂ­s, dos investimentos recentes e do preço do mel, a expansĂŁo da apicultura orgĂąnica em Portugal Ă© restrita. Para abordar essa questĂŁo, a Federação Nacional dos Apicultores de Portugal, em colaboração com o Instituto PolitĂ©cnico de Bragançã, lançou o projeto BIOIMPACT. Este projeto visa identificar os motivos que restringem a expansĂŁo da apicultura orgĂąnica portuguesa e aumentar o nĂșmero de apicultores dedicados Ă  produção orgĂąnica. O projeto coleta as experiĂȘncias dos atuais operadores orgĂąnicos, permitindo que potenciais novos operadores compreendam o potencial desse setor. As informaçÔes sĂŁo obtidas por meio de questionĂĄrios individuais, que avaliam a atividade apĂ­cola em modo orgĂąnico.info:eu-repo/semantics/publishedVersio

    The evolution and current status of organic beekeeping in Portugal

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    The Portuguese beekeeping sector is one of the most resilient and persistent farming activities in the last decade. In the last five years, the figures reveal a counter cycle behavior with an increment in the number of colonies, apiaries and beekeepers, as shown in the National Beekeeping Program: there are 16.403 beekeepers with a total of 550.757 colonies. Following the same positive trend, the conversion from conventional to organic production as evolved in the period 2004/2012, from 738 up to 28.607 colonies (5% of the beekeeping sector), with a estimated production of 570 tons of certified honey, corresponding to an income of € 1.800.000. Even so, these figures are still below other European countries with similar environment potentialities like Italy, where the organic beekeeping represents more than 100.000 colonies (8% of total colonies) and even below the 7.6% that the organic farming represents in the Portuguese agriculture, which would be equivalent to more than 42.000 colonies. The sector organization and professionalization, the country natural resources (diverse nectar flows of high value) and the additional value given to organic products were expected to be self-sufficient factors for a sustainable enhancement of the number of organic beekeepers. However, it is been clear from the Portuguese experience that those key factors do not work alone without a continuous promotion of the production mode, focusing in the certification procedure, the specificities of beekeeping management and in the market approach: the distribution of Portuguese organic beekeepers is more concentrated in areas where the local organizations are more proactive towards the organic production. Additionally, it is interesting to notice that the profile of the organic beekeeper reveal some particularities: it is younger, with an academic background, frequently a degree in natural sciences or technologies complemented by specific beekeeping training. The interest for organic beekeeping, which represents the main income, arose from the commercial advantages, the environment protection but also from the influence of the local organization. More than 90% of the present Portuguese organic beekeepers are strongly engaged with the production mode, but highlight as the weakest points the efficacy and limitations of varroa treatments and a market value below their expectations

    Efficacy of menthol as an anesthetic for tambaqui (Colossoma macropomum, Characiformes: Characidae)

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    Anesthetics are important in fish culture to reduce handling stress and mortality. The objective of this work is to investigate menthol as an anesthetic for tambaqui. In the first series of tests, fish were exposed to various concentrations of menthol to evaluate induction time and stress responses. The second series examined the effect of exposure period to menthol at 150 mg/L on recovery time. The third assessed the best dosage for juveniles in larger tambaqui. The best concentration for surgical anesthesia is 150 mg/L. At this concentration the induction time is short, but their recovery time is significantly longer than that for lower concentrations. For biometry procedures, the best concentration is 100 mg/L. At this concentration the induction time is prolonged, but the recovery time is within the desired period. Recovery time for fish exposed to 150 mg/L is equal for 10, 20 or 30 minutes of exposure. The results confirmed that menthol is an adequate anesthetic for tambaqui.Os anestĂ©sicos sĂŁo importantes na piscicultura para reduzir o estresse e a mortalidade no manejo. Este trabalho tem como objetivo determinar a eficĂĄcia do mentol para tambaqui durante o manejo. Na primeira sĂ©rie de testes, foi examinado o efeito da concentração de anestĂ©sico sobre indução Ă  anestesia e o estresse de tambaqui. Na segunda sĂ©rie de testes, foi avaliada a recuperação dos peixes apĂłs a exposição a uma concentração de 150 mg/L de mentol por diferentes tempos. Na terceira sĂ©rie, foi avaliada se a melhor concentração encontrada para juvenil (150 mg/L) tambĂ©m era adequada para peixes maiores. A melhor concentração para uma anestesia cirĂșrgica foi 150 mg/L, pois o tempo de indução Ă© rĂĄpido, porĂ©m a recuperação Ă© significativamente mais demorada do que para as menores concentraçÔes testadas. Para uma anestesia, com finalidade de biometria, a melhor concentração foi 100 mg/L. Nesta concentração o tempo de indução Ă  anestesia Ă© prolongado, porĂ©m o tempo de recuperação estĂĄ dentro da faixa considerada adequada. O tempo de recuperação do tambaqui quando exposto a 150 mg/L Ă© significativamente igual para 10, 20 e 30 minutos de anestesia. Os resultados obtidos mostram que o mentol Ă© um anestĂ©sico eficiente para o tambaqui

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio
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