Recursos de colección

Biblioteca Digital do IPB (53.442 recursos)

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PTV - Publicações em Proceedings Indexadas ao ISI

Mostrando recursos 1 - 11 de 11

  1. Determination of 2,4,6-trichloroanisole by cyclic voltammetry

    Freitas, Patrícia; Dias, L.G.; Peres, António M.; Castro, Luís M.; Veloso, Ana C.A.
    The electrochemical reduction of 2,4,6-trichloroanisole (TCA), a chlorinated arene with electron-donating substituents, was evaluated by cyclic voltammetry (CV). TCA is a major concern for the winery industry since it is related with “cork taint”, a wine defect. The results obtained showed that CV could be used to detect and quantify TCA in standard solutions. Linear relationships could be set between the current amplitude and TCA concentrations (R>0.990) with detection and quantification limits of 0.08 and 0.26 ppm. Although, these preliminary limits are higher than the human sensory threshold (5 ppt in wine), the simplicity of the methodology confers this study...

  2. Polymeric biophenols in olive mill wastewaters

    Cardoso, Susana M.; Falcão, Soraia; Peres, António M.; Pereira, Olívia R.; Domingues, M.R.M.

  3. Bioaccumulation of metals by Mugil saliens under chronic exposure to contamined sediments: Gill histopathological changes

    Fernandes, Conceição; Monteiro, Sandra Mariza; Fontaínhas-Fernandes, A.; Salgado, Maria Antónia
    The Esmoriz/Paramos coastal lagoon, is a habitat of ecological importance due to the presence of unique animal and plant species. During the past few years its immersed area has been gradually reduced due to effluent discharges and siltation. The major contaminants in the lagoon are derived from a multitude of nonpoint sources associated with urbanization and industrial activities within the watershed. Heavy metals are probably a class of pollutants contributing to the observed decline of fish species. The metal content in the water and sediments in the lagoon were investigated as well as gill metal bioaccumulation and gill histopathological changes of the grey leaping mullet, Mugil saliens.

  4. Oxidative stress enzymes and mitochondrial bioenergetics in wild Liza saliens exposed to heavy metals

    Fernandes, Conceição; Fontaínhas-Fernandes, A.; Peixoto, Francisco P.; Salgado, Maria Antónia
    The Esmoriz-Paramos coastal lagoon represents an ecosystem of great physical and ecological significance. However, as a result of industrial, agricultural and antropogenic activities this habitat has been progressively degrading over the last decades. The heavy metal contamination is an important factor to the decline of sediments quality and may adversely affect fish health. In the present work the leaping grey mullet Liza saliens was studied because it is the dominant endemic species in the lagoon. It is a filter feeder and also being a detritus-mud feeder, it is therefore exposed to contaminated sediments.

  5. Probabilistic simulation of children exposure to migrants from packaging: photoinitiators from printing inks

    Machado, Carla; Fernandes, Conceição; Pereira, Joel; Poças, Maria de Fátima
    This paper presents an exercise to simulate exposure of Portuguese consumers to benzophenone, a photoinitiator used in packaging printing inks. The simulation model combines experimental data of benzophenone concentration actually found in packages collected from the market and food consumption and packaging usage data obtained from a database. The model follows a probabilistic approach: the distribution of occurrence data was combines with food consumption data in a probabilistic simulation with the Monte Carlo sampling method. Exposure values found indicate that benzophenone levels of exposure are of no concern healthwise according to the tolerable daily intake defined by EFSA.

  6. Performance of three mechanical harvesting systems for olives in Portugal

    Almeida, Arlindo; Peça, José; Pinheiro, Anacleto; Dias, António; Santos, Luís S.S. dos; Reynolds, Domingos; Lopes, João
    Three mechanical harvesting systems for olives have been tested in field trials in the two main Portuguese regions of olive production: Trás-os-Montes and Alentejo. These tests took place in traditional olive orchards with 100 to 150 trees per hectare. In the three systems, olives were harvested with the same trunk shaker and were collected manually (system I); with a tractor mounted rolling canvas (system II); with an inverted umbrella (system III). Results are revealed in terms of working rates. The main factors that influence the systems performance are discussed.

  7. Mead production: comparison of different production scales (preliminary results)

    Gomes, Teresa; Barradas, Carla; Dias, Teresa; Andrade, João Verdial; Morais, Jorge Sá; Ramalhosa, Elsa; Estevinho, Leticia M.
    Mead production represents a possible economic alternative to honey producers that intend to obtain honey products with surplus value. From that the present work aims to study the influence of using different production scales on the quality of the final mead obtained and on the process performance. Increasing the production scale almost ten times (1.5 to 20 L), some differences were observed. Maximum specific growth rates equal to 0.045 and 0.038 h-1 were obtained for fermentations carried out at 1.5 and 20 L, respectively. The time course of glucose and glycerol were similar for both production scales. Nevertheless, slight differences...

  8. Physical characteristics and drying kinetics of Portuguese "Longal" chestnut

    Ramalhosa, Elsa; Lamas, Hugo; Pereira, J.A.; Morais, A.M.M.B.
    Chestnut is a fruit of great importance in Portugal, being generally sold fresh or frozen. Alternative products may be obtained by hot air drying. The present work is on the dehydration behavior of Portuguese ‘Longal’ chestnut, that is the most used in industry. Different models for representing the variations of water content and drying rate along time were tested successfully. As expected, higher temperatures correspond to faster drying processes. The apparent diffusivity was predicted by Fick’s second law equation, and it ranged from 1.25x10-11 m2/s, at 20ºC, to 8.42x10-10 m2/s, at 100ºC.

  9. Analysis of yearly variation on olive yields and its relation to alternate fruiting

    Rodrigues, M.A.; Arrobas, Margarida
    In this study, the variability in olive yields per individual tree within homogeneous plots of trees was analyzed as well as the variability on the mean olive yields of each plot of trees over a period of years. Data supporting this work were recorded from two dry farmed olive orchards located in Bragança and Mirandela, NE Portugal. From each olive orchard data were collected separately from two different plots, where the ground was managed by conventional tillage or by using post-emergence herbicides.

  10. Rumex induratus leaves: phytochemical profiling and antioxidant activity

    Guerra, Luís; Pereira, Carla; Rodrigues, M.A.; Andrade, P.B.; Gonçalves, Rui; Seabra, R.M.; Valentão, P.
    Several species of the Rumex (Polygonaceae) genus have been used in traditional medicine, although their high oxalic acid content has been implicated in oxalic intoxication, mainly la children. Rumex induratus Boiss & Reuter is an endemic Liberian herb that prefers rocky habitats of the thermo Mediterranean region.

  11. Efficiency of organic nitrogen fertilization of potato in Northeast Portugal

    Rodrigues, M.A.; Coutinho, João; Martins, Fernando
    The study was conducted over a 4 year period with the purpose of measuring N mineralization using an in situ incubation technique, following the application of farmyard manure, poultry manure or municipal solid waste. The results varied from –10 % (net immobilization) to +28 % (net mineralization) in relation to the total organic N applied. N fluxes were assessed through plant N analysis during the growing season and through determination of potato tuber dry weight (TDW), N uptake by tubers and the apparent N recovery (ANR) of added N at harvest. Organic material applications slightly increased TDW above the control...

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