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Repositório do Instituto Politénico de Castelo Branco (14.319 recursos)

O Repositório Científico do Instituto Politécnico de Castelo Branco tem como objectivos fundamentais a divulgação, a preservação em formato digital e a partilha do conhecimento científico gerado na instituição, constituindo-se numa ferramenta de valor acrescentado porque permite aumentar a visibilidade e o impacto da investigação desenvolvida.

ESACB - Artigos em revistas com arbitragem científica

Mostrando recursos 1 - 20 de 141

  1. A comparison of the growth performance between cattle reared in conventional systems and in feral condition

    Nogales, Sergio; Calderón, Juan; Lupi, T.M.; Bressan, Maria Cristina; Delgado, Juan Vicente; Camacho, María Esperanza
    Feral and conventional growth performances were compared using Marismeña cattle as a model. Marismeña calves are commonly reared under feral conditions in one of the most important reserves of Europe (Doñana National Park, Spain). Data recording in these natural conditions faces compromises as animals are only handled once per year. This fact has to be saved to obtain efficient estimations for the biological growth curve of cattle reared under feral conditions. On the one hand, we assessed the inference of the theoretical influence of human management on cattle growth. On the other hand, we studied the fitness of the best...

  2. Organic amendments as a source of phosphorus: agronomic and environmental impact of different animal manures applied to an acid soil.

    Monteiro, M.C.H.; Roboredo, M.; Carneiro, J.P.; Duarte, A.C.; Torrent, J.; Sharpley, A.
    Phosphorus (P) is a non-renewable resource highlighting the significance of developing and using alternative P sources for a sustainable agriculture. The work aims to compare the effects of different organic amendments (OA) and a mineral P fertiliser as reference on P use efficiency by the crop, and on P losses to runoff waters and eroded sediments. A two-year field trial was conducted in a Dystric Regosol with Lolium sp. Treatments were: cattle manure compost (CM), solid fraction of swine (SS) and duck (DS) slurries and triple superphosphate (TSP), each applied at 50 kg P ha−1 year−1. Olsen P (mg P...

  3. Organic amendments as a source of phosphorus: agronomic and environmental impact of different animal manures applied to an acid soil.

    Monteiro, M.C.H.; Roboredo, M.; Carneiro, J.P.; Duarte, A.C.; Torrent, J.; Sharpley, A.
    Phosphorus (P) is a non-renewable resource highlighting the significance of developing and using alternative P sources for a sustainable agriculture. The work aims to compare the effects of different organic amendments (OA) and a mineral P fertiliser as reference on P use efficiency by the crop, and on P losses to runoff waters and eroded sediments. A two-year field trial was conducted in a Dystric Regosol with Lolium sp. Treatments were: cattle manure compost (CM), solid fraction of swine (SS) and duck (DS) slurries and triple superphosphate (TSP), each applied at 50 kg P ha−1 year−1. Olsen P (mg P...

  4. Bioavailability of phosphorus from composts and struvite in acid soils.

    Monteiro, M.C.H.
    The objective of this study was to assess the type and fractions of phosphorus (P) forms in composts and struvite and how these P forms affect the bioavailability of P in the soil. P fertilization was performed with compost from sewage sludge (CSS), compost from poultry litter (CPL) and struvite (SV) and compared with single superphosphate (SSP). P forms were quantified through a sequential fractionation scheme. The first extraction was performed with H2O, the second with 0.5 M NaHCO3, the third with 0.1 M NaOH and the fourth with 1 M HCl. The release of P over time, after soil...

  5. Bioavailability of phosphorus from composts and struvite in acid soils.

    Monteiro, M.C.H.
    The objective of this study was to assess the type and fractions of phosphorus (P) forms in composts and struvite and how these P forms affect the bioavailability of P in the soil. P fertilization was performed with compost from sewage sludge (CSS), compost from poultry litter (CPL) and struvite (SV) and compared with single superphosphate (SSP). P forms were quantified through a sequential fractionation scheme. The first extraction was performed with H2O, the second with 0.5 M NaHCO3, the third with 0.1 M NaOH and the fourth with 1 M HCl. The release of P over time, after soil...

  6. IDE ‑OTALEX C: A Primeira Infraestrutura de Dados Espaciais transfronteiriça entre Portugal e Espanha

    Ceballos, Fernando; Caballero, Carmen; Vivas, Pedro; Batista, T.; Garrido, Ana; Rojas, Manuel; Pérez, Marisa; Reis, Sara; Quinta-Nova, L.C.; Fernandez, P.; Roque, N.; Cabaceira, S.; Cabezas, José; Pinto-Gomes, Carlos; Carreira, Duarte
    Em 2007 criou ‑se a primeira Infraestrutura de Dados Espaciais transfronteiriça entre Portugal e Espanha (IDE ‑OTALEX – www.ideotalex.eu), que constituiu o Observatório Territorial e Ambiental Alentejo e Extremadura, ao qual se incorporou, em 2011, a região Centro de Portugal, que no total abrange uma superfície de 92.500 km2. Assim, surgiu o Observatório Territorial Alentejo ‑Extremadura ‑Centro (OTALEX C), possibilitando a integração da informação produzida pelas diversas instituições que desenvolvem as suas competências de planeamento e gestão territorial, nestas três regiões. Tendo como objetivo a monitorização e análise de alterações decorrentes de fenómenos naturais e da atividade humana sobre o...

  7. IDE ‑OTALEX C: A Primeira Infraestrutura de Dados Espaciais transfronteiriça entre Portugal e Espanha

    Ceballos, Fernando; Caballero, Carmen; Vivas, Pedro; Batista, T.; Garrido, Ana; Rojas, Manuel; Pérez, Marisa; Reis, Sara; Quinta-Nova, L.C.; Fernandez, P.; Roque, N.; Cabaceira, S.; Cabezas, José; Pinto-Gomes, Carlos; Carreira, Duarte
    Em 2007 criou ‑se a primeira Infraestrutura de Dados Espaciais transfronteiriça entre Portugal e Espanha (IDE ‑OTALEX – www.ideotalex.eu), que constituiu o Observatório Territorial e Ambiental Alentejo e Extremadura, ao qual se incorporou, em 2011, a região Centro de Portugal, que no total abrange uma superfície de 92.500 km2. Assim, surgiu o Observatório Territorial Alentejo ‑Extremadura ‑Centro (OTALEX C), possibilitando a integração da informação produzida pelas diversas instituições que desenvolvem as suas competências de planeamento e gestão territorial, nestas três regiões. Tendo como objetivo a monitorização e análise de alterações decorrentes de fenómenos naturais e da atividade humana sobre o...

  8. Bioactive compounds of portuguese virgin olive oils discriminate cultivar and ripening stage

    Peres, M.F.; Martins, L.L.; Mourato, M.; Vitorino, M.C.; Dias, S.F.
    Só está disponível o resumo.

  9. Influence of enzymes and technology on virgin olive oil composition

    Peres, M.F.; Martins, L.L.; Dias, S.F.
    Só está disponível o resumo.

  10. Using apparent density of paper from hardwood kraft pulps to predict sheet properties, based on unsupervised classification and multivariable regression techniques

    Anjos, O.; García-Gonzalo, E.; Santos, A.J.A.; Simões, R.; Martínez-Torres, J.; Pereira, H.; García-Nieto, P.J.
    Paper properties determine the product application potential and depend on the raw material, pulping conditions, and pulp refining. The aim of this study was to construct mathematical models that predict quantitative relations between the paper density and various mechanical and optical properties of the paper. A dataset of properties of paper handsheets produced with pulps of Acacia dealbata, Acacia melanoxylon, and Eucalyptus globulus beaten at 500, 2500, and 4500 revolutions was used. Unsupervised classification techniques were combined to assess the need to perform separated prediction models for each species, and multivariable regression techniques were used to establish such prediction models....

  11. Fibre morphological characteristics of kraft pulps of Acacia melanoxylon estimated by NIR-PLS-R models

    Pereira, H.; Santos, A.J.A.; Anjos, O.
    In this paper, the morphological properties of fiber length (weighted in length) and of fiber width of unbleached Kraft pulp of Acacia melanoxylon were determined using TECHPAP Morfi® equipment (Techpap SAS, Grenoble, France), and were used in the calibration development of Near Infrared (NIR) partial least squares regression (PLS-R) models based on the spectral data obtained for the wood. It is the first time that fiber length and width of pulp were predicted with NIR spectral data of the initial woodmeal, with high accuracy and precision, and with ratios of performance to deviation (RPD) fulfilling the requirements for screening in...

  12. Estimation of Acacia melanoxylon unbleached Kraft pulp brightness by NIR spectroscopy

    Santos, A.J.A.; Anjos, O.; Pereira, H.
    Aim of the study: The ability of NIR spectroscopy for predicting the ISO brightness was studied on unbleached Kraft pulps of Acacia melanoxylon R. Br. Area of study: Sites covering littoral north, mid interior north and centre interior of Portugal. Materials and methods: The samples were Kraft pulped in standard identical conditions targeted to a kappa number of 15. A Near Infrared (NIR) partial least squares regression (PLSR) model was developed for the ISO brightness prediction using 75 pulp samples with a variation range of 18.9 to 47.9 %. Main results: Very good correlations between NIR spectra and ISO brightness were obtained. Ten...

  13. Prediction of blackwood kraft pulps yields with wood NIR–PLSR models

    Santos, A.J.A.; Anjos, O.; Pereira, H.
    Pulp yield is an important measure of pulpwood quality, which is used regularly by the pulp and paper industry for which the possibility of using rapid methods to predict pulp yield would be very useful for screening and quality control. This work addresses the prediction of Kraft pulp yield under standard identical conditions and targeted to a kappa number of 15, using near-infrared (NIR) partial least squares regression modelling. A total of 75 pulp samples of Acacia melanoxylon R. Br. (blackwood) with a pulp yield variation range of 47.0–58.2 % were used. Very good correlations between NIR spectra and pulp...

  14. Kinetics of odorant compounds in wine brandies aged in different systems

    Caldeira, I.; Santos, R.; Silva, J.M.R.; Anjos, O.; Mira, H.; Belchior, A.P.; Canas, S.
    The odorants compounds of aged wine brandies comprise compounds deriving from the wood, from the distillate and from the reactions that occur inside the barrel. The aim of this work was to study the kinetics of the odorant compounds of a wine brandy during two years of ageing in two ageing systems. The odorant compounds in the analysed brandies changed significantly over the time, but with different evolution patterns. The wood related compounds increased over time, with the highest increase in the first months of ageing. The kinetics of cis, trans-β-methyl-γ-octalactone, acetovanillone and of seven volatile phenols are established for...

  15. FTIR–ATR spectroscopy applied to quality control of grape-derived spirits

    Anjos, O.; Santos, A.J.A.; Estevinho, L.M.; Caldeira, I.
    The Fourier transform infrared (FTIR) spectroscopic method with attenuated total reflectance (ATR) was used for predicting the alcoholic strength, the methanol, acetaldehyde and fusel alcohols content of grape-derived spirits. FTIR-ATR spectrum in the mid-IR region (4000-400 cm(-1)) was used for the quantitative estimation by applying partial least square (PLS) regression models and the results were correlated with those obtained from reference methods. In the developed method, a cross-validation with 50% of the samples was used for PLS analysis along with a validation test set with 50% of the remaining samples. Good correlation models with a great accuracy were obtained for...

  16. Physicochemical and sensory evaluation of wine brandies aged using oak and chestnut wood simultaneously in wooden barrels and in stainless steel tanks with staves

    Canas, S.; Caldeira, I.; Anjos, O.; Lino, J.; Soares, A.; Belchior, A. P.
    This study provides innovative information on the simultaneous use of Limousin oak and chestnut wood in the ageing of wine brandy. Ageing was performed in 650-L wooden barrels and in 3000-L stainless steel tanks with staves over a 2-year period. Effect of both kinds of wood in the brandy features depended on the ageing technology. Stainless steel tanks with staves originated lower enrichment of the brandy in dry extract (0.89 vs. 1.25 g L−1), total phenolics (22.33 vs. 29.40) and low molecular weight extractable compounds (119.83 vs. 231.65 mg L−1), but promoted a faster evolution of the analytical colour (lower...

  17. Prediction of tension properties of cork from its physical properties using neural networks

    Iglesias, C.; Anjos, O.; Martínez, J.; Pereira, H.; Taboada, J.
    A tool to predict the tensile properties of cork was applied in order to be used for material and application selection. The mechanical behaviour of cork under tensile stress was determined in the tangential and axial direction. Cork planks of two commercial quality classes were used and samples were taken at three radial positions in the planks.For the construction of the predictive model, nine properties were measured: mechanical properties (Young’s modulus, fracture stress and fracture strain) and the physical properties (porosity, number of pores, density, approximation of the pores to elliptical and circular shape and distance to the nearest pore)....

  18. Prediction of mechanical strength of cork under compression using machine learning techniques

    García, Á.; Anjos, O.; Iglesias, C.; Pereira, H.; Martínez, J.; Taboada, J.
    In this study, the accuracy of mathematical techniques such as multiple linear regression, clustering, decision trees (CART) and neural networks was evaluated to predict Young’s modulus, compressive stress at 30% strain and instantaneous recovery velocity of cork. Physical properties, namely test direction, density, porosity and pore number, as well as test direction were used as input. The better model was achieved when a classification problem was performed. Only compressive stress at 30% strain can be predicted with neural networks with an error rate of about 20%. The prediction of Young’s modulus and instantaneous recovery velocity led to unacceptably high error...

  19. Neural networks applied to discriminate botanical origin of honeys

    Anjos, O.; Iglesias, C.; Peres, M.F.; Martínez, J.; García, Á.; Taboada, J.
    The aim of this work is develop a tool based on neural networks to predict the botanical origin of honeys using physical and chemical parameters. The managed database consists of 49 honey samples of 2 different classes: monofloral (almond, holm oak, sweet chestnut, eucalyptus, orange, rosemary, lavender, strawberry trees, thyme, heather, sunflower) and multifloral. The moisture content, electrical conductivity, water activity, ashes content, pH, free acidity, colorimetric coordinates in CIELAB space (L(∗), a(∗), b(∗)) and total phenols content of the honey samples were evaluated. Those properties were considered as input variables of the predictive model. The neural network is optimised...

  20. Application of FTIR-ATR spectroscopy to the quantification of sugar in honey

    Anjos, O.; Campos, M. G.; Ruiz, P. C.; Antunes, P.
    A Fourier transform infrared spectroscopic method with attenuated total reflectance (FTIR-ATR) and partial least squares (PLS) regression model for the prediction of sugar content in honey samples was calculated. Standards of trehalose, glucose, fructose, sucrose, melezitose, turanose and maltose were used to identify and quantify the individual sugar components in 63 honey samples by HPAEC-IPAD. Fructose and glucose are the highest sugars in honey with an average value of 36% and 26%, respectively. The 1stDer spectra with MSC or SLS in the wave number range from 1500 to 750cm(-1) provide the best calibration model with a r(2) of 86.60 and...

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