630 research outputs found

    Dynamics of drinking water biofilm in flow/non-flow conditions

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    Drinking water biofilm formation on polyvinyl chloride (PVC), cross-linked polyethylene (PEX), high density polyethylene (HDPE) and polypropylene (PP) was followed in three different reactors operating under stagnant or continuous flow regimes. After one week, a quasi-steady state was achieved where biofilm total cell numbers per unit surface area were not affected by fluctuations in the concentration of suspended cells. Metabolically active cells in biofilms were around 17-35% of the total cells and 6-18% were able to form colony units in R(2)A medium. Microbiological analysis showed that the adhesion material and reactor design did not affect significantly the biofilm growth. However, operating under continuous flow (0.8-1.9 Pa) or stagnant water had a significant effect on biofilm formation: in stagnant waters, biofilm grew to a less extent. By applying mass balances and an asymptotic biofilm formation model to data from biofilms grown on PVC and HDPE surfaces under turbulent flow, specific growth rates of bacteria in the biofilm were found to be similar for both materials (around 0.15 day(-1)) and much lower than the specific growth rates of suspended bacteria (around 1.8 day(-1))

    Medicago spp. as potential sources of bioactive isoflavones: Characterization according to phylogenetic and phenologic factors

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    A high variety of plant species are often proposed as potential natural sources of specific bioactive components, with emphasis in phenolic compounds. However, the ability to produce a determined phytochemical might be variable, even among species with close phylogeny. Furthermore, the metabolic dynamics vary greatly according to phenologic factors. Herein, it was verified whether isoflavone production in Medicago spp. is more associated with phylogenetic or phenologic determinants, to define the optimal productive conditions. Isoflavone profiles were characterized in field-grown Medicago species in three phenologic stages. Isoflavones were extracted by matrix solid-phase dispersion method and analyzed using high-performance liquid chromatography coupled with a diode-array detector. The obtained data were evaluated by a generalized linear model (GLM) and linear discriminant analysis (LDA). Formononetin, genistein and irilone were the most abundant isoflavones, reaching values higher than those present in acknowledged plant sources like soy or red clover. Outputs from GLM and LDA indicate that the phylogenetic factors are the most defining criteria. This study promotes Medicago spp. as potential isoflavone sources, particularly because the effects of these compounds are highly dependent on their type and concentration, with potential application as foodstuff, feedstuff, or in the nutraceutical and pharmaceutica l industry.Visnevschi-Necrasov and João C.M. Barreira are grateful to ‘‘FCT – Fundação para a Ciência e a Tecnologia’’ for their Grants (SFRH/BD/31734/2006 and SFRH/BPD/72802/2010, respectively). S.C. Cunha is grateful to ‘‘POPH-QREN – Tipologia 4.2, Fundo Social Europeu e Fundo Nacional MCTES’’.info:eu-repo/semantics/publishedVersio

    Phylogenetic insights on the isoflavone profile variations in Fabaceae spp.: Assessment through PCA and LDA

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    Legumes (Fabaceae) are important crops, known as sources of food, feed for livestock and raw materials for industry. Their ability to capture atmospheric nitrogen during symbiotic processes with soil bacteria reduces the need for expensive chemical fertilizers, improving soil and water quality. Several Fabaceae species are acknowledged for the high levels of secondary metabolites. Isoflavones are among the most well-known examples of these compounds, being recognized for their several types of biological activity. Herein, isoflavone profiles were characterized in nine species of four Fabaceae genera (Biserrula, Lotus, Ornithopus and Scorpiurus). Plants were harvested in the late flower physiological stage to prevent biased results due to naturally occurring variations along the vegetative cycle. Isoflavones were extracted using matrix solid-phase dispersion and analyzed by high performance liquid chromatography/diode-array detection. The detected profiles revealed significant differences, inclusively among species belonging to the same genus, indicating that other factors besides the genotypic features contribute to the expression of these phenolic compounds. The classification of the results by principal component analysis placed species belonging to the same genus in different clustering groups, proving this latter assumption. However, the detected profiles proved to be characteristic of the assayed, as it was proved by the applied linear discriminant analysis.info:eu-repo/semantics/publishedVersio

    Phytochemical profiling of underexploited Fabaceae species: Insights on the ontogenic and phylogenetic effects over isoflavone levels

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    There is an increasing trend towards finding alternative sources of valued phytochemicals due to their diverse potentialities in food industry and pharmaceutical applications. Phenolic compounds, in particular, have been the focus of several profiling reports, but isoflavones characterization has been studied in fewer cases and in a very limited group of plant species. Despite their acknowledged bioactivity, there's actually a strict number of plants validated for their isoflavones contents. In a previous report, we have identified nine Leguminosae species (from genera Biserrula, Lotus, Ornithopus and Scorpiurus) as potential alternative sources of these phenolic compounds. However, the isoflavone profiles are highly modulated by the ontogenic stage. Therefore, the present study was conducted in the same Leguminosae species, but harvested at three sequential vegetative development stages: vegetative elongation, late bud and late flowering, with the main purpose of assessing the evolution of isoflavones content throughout the plant development. In general, the plant species from Biserrula and Lotus genera showed the highest potential as new natural sources of isoflavones, especially owing their high levels of biochanin A. Independently of the plant species, it was possible to identify the phenologic stages where each of the quantified isoflavones is maximized. These findings are useful to predict isoflavone yields according to harvesting time, validating the potential use of the studied plants in innovative food formulations.João C.M. Barreira and T. Visnevschi-Necrasov are grateful to “FCT - Fundação para a Ciência e a Tecnologia” for their grants (SFRH/BPD/72802/2010 and SFRH/BD/31734/2006, respectively) financed by POPH-QREN and subsidized by FSE and MCTES. This work received financial support from the European Union (FEDER funds through COMPETE) and National Funds (FCT) through project Pest-C/EQB/LA0006/2013. The work also received financial support from the European Union (FEDER funds) under the framework of QREN through Project NORTE-07-0124 FEDER-000069.info:eu-repo/semantics/publishedVersio

    Advances in isoflavone profile characterisation using matrix solid-phase dispersion coupled to HPLC/DAD in medicago species

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    Analytical methods used in phytochemistry analysis are limited by the sample preparation step, which should ideally be fast, accurate, ecofriendly and achievable using low quantities of the sample. Matrix solid-phase dispersion (MSPD) may be a good alternative for combining extraction and purification procedures, thereby reducing the indicated limitations. Objective-Applying an MSPD extraction procedure coupled to high-performance liquid chromatography diode-array detection (HPLC/DAD) as an alternative methodology to evaluate isoflavone profiles. Methods-Isoflavone profiles were determined for the leaves of nine species of Medicago in the late flower phenological stage (one or more nodes with 50% open flowers, no seed pods). Extraction was performed following MSPD, and isoflavone profiles were characterised using HPLC/DAD. The quantified amounts were compared with previous results in different species commonly recognised as good sources of isoflavones. Results-Formononetin was the major isoflavone in most species, except M. polymorpha and M. truncatula. The isoflavone amounts were significantly different among the assayed species, with M. orbicularis and M. arabica as the major isoflavone sources, while M. rigidula presented the lowest contents. Furthermore, the detected differences allow electing the best species as a primary source of a specific isoflavone. Conclusion-The MSPD allowed good extraction efficiency, reproducibility and recovery. Some of the species showed relevant isoflavone contents, even when compared with acknowledged plant sources such as soy or red clover. To the best of our knowledge the results presented are reported for the first time in these species.T. Visnevschi-Necrasov and João C.M. Barreira are grateful to ‘FCT - Fundação para a Ciência e a Tecnologia’ for their grants (BD/ 31734/2006 and SFRH/BPD/72802/2010, respectively). S.C. Cunha is grateful to ‘POPH-QREN - Tipologia 4.2, Fundo Social Europeu e Fundo Nacional MCTES’.info:eu-repo/semantics/publishedVersio

    Livro Oficial do Parque Natural do Tejo Internacional

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    O Parque Natural do Tejo Internacional (PNTI) existe há 19 anos, sobrepondo-se parcialmente à Zona de Proteção Especial do Tejo Internacional, Erges e Ponsul, classificada ao abrigo da Diretiva Aves, integra o Parque Internacional Tejo-Tajo, desde 2013, e foi classificado como Reserva da Biosfera da UNESCO, em 2016. Entre outras iniciativas, que, no seu conjunto, dão corpo a uma gestão ativa e de proximidade, em abril de 2017, foi lançado o Projeto Piloto para a Gestão Colaborativa do PNTI, envolvendo sete entidades: os três Municípios (Castelo Branco, Idanha-a-Nova e Vila Velha de Ródão), o Instituto da Conservação da Natureza e das Florestas, a Quercus, o Instituto Politécnico de Castelo Branco e a Associação Empresarial da Beira Baixa. Pretendeu-se constituir uma dinâmica de colaboração e partilha, em que as diferentes entidades colocaram ao serviço do PNTI os seus saberes e competências. Este Projeto Piloto permitiu evoluir para a conceção de um novo modelo de cogestão para as áreas protegidas. Trata-se de um instrumento que marcará o futuro da valorização do nosso capital natural, baseado na proximidade aos territórios e às pessoas que nele habitam, exercem as suas atividades económicas e os visitam, mas também baseado em mais conhecimento, comunicação e reforço identitário. E este livro, que ilustra os atributos desta parcela do território, como é valiosa, singular e pode catalisar o seu desenvolvimento, é já uma evidência dos bons resultados que é possível alcançar quanto se trabalha em rede. É compilada informação disponível sobre o PNTI que se disponibiliza, de modo muito acessível a quem a lê. Informação que contribuirá para a promoção dos valores presentes nesta área protegida, dos seus habitats, espécies e paisagens que lhe conferem uma identidade tão própria. Reforçará ainda os comportamentos que reconhecem o valor dos serviços que os ecossistemas prestam que, não valorizados pelo mercado, são indispensáveis para o bem-estar da sociedade, tais como o controlo da erosão, o sequestro de carbono, a regulação do ciclo hidrológico, a conservação da biodiversidade, a redução da suscetibilidade ao fogo, os espaços de lazer e fruição, entre outros.info:eu-repo/semantics/publishedVersio

    Probing Isospin Dynamics in Halo Nuclei

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    Nuclear many-body theory is used to study nuclear matter and finite nuclei at extreme isospin. In-medium interactions in asymmetric nuclear matter are obtained from (Dirac-) Brueckner theory. Neutron skin formation in Ni and Sn isotopes is investigated by relativistic mean-field calculations in DDRH theory with density dependent meson-nucleon vertices. Applications to light nuclei are discussed with special emphasis on pairing and core polarization in weakly bound nuclei. Approaches accounting for continuum coupling in dripline pairing and core polarization are presented. Calculations for the halo nuclei 8^8B, 11^{11}Be and 19^{19}C show that shell structures are dissolving when the driplines are approached. Relativistic breakup data are well described by eikonal calculations.Comment: 10 pages, 8 figure

    Modeling Life as Cognitive Info-Computation

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    This article presents a naturalist approach to cognition understood as a network of info-computational, autopoietic processes in living systems. It provides a conceptual framework for the unified view of cognition as evolved from the simplest to the most complex organisms, based on new empirical and theoretical results. It addresses three fundamental questions: what cognition is, how cognition works and what cognition does at different levels of complexity of living organisms. By explicating the info-computational character of cognition, its evolution, agent-dependency and generative mechanisms we can better understand its life-sustaining and life-propagating role. The info-computational approach contributes to rethinking cognition as a process of natural computation in living beings that can be applied for cognitive computation in artificial systems.Comment: Manuscript submitted to Computability in Europe CiE 201

    Tejo Internacional. Guia de Visita.

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    Em sintonia com os objetivos fixados aquando da criação do Parque Natural do Tejo Inernacional, em agosto de 2000, assume-se como propósito deste guia a apresentação de um instrumento de informação e orientação que potencie o respeito pelos valores intrínsecos do PNTI, bem como o usufruto e fruição equilibrada dos mesmos. Neste contexto procede-se a uma breve descrição caracterizadora do Território do Parque, informação relativa ao apoio à visitação, é ainda apresentado um elenco de espécies de fauna e flora.info:eu-repo/semantics/publishedVersio

    Vibrational properties of amorphous silicon from tight-binding O(N) calculation

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    We present an O(N) algorithm to study the vibrational properties of amorphous silicon within the framework of tight-binding approach. The dynamical matrix elements have been evaluated numerically in the harmonic approximation exploiting the short-range nature of the density matrix to calculate the vibrational density of states which is then compared with the same obtained from a standard O(N4N^4) algorithm. For the purpose of illustration, an 1000-atom model is studied to calculate the localization properties of the vibrational eigenstates using the participation numbers calculation.Comment: 5 pages including 5 ps figures; added a figure and a few references; accepted in Phys. Rev.
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