ESTM - Artigos em revistas internacionais
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Browsing ESTM - Artigos em revistas internacionais by Sustainable Development Goals (SDG) "02:Erradicar a Fome"
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- An empirical comparison of Canonical Correspondence Analysis and STATICO in the identification of spatio-temporal ecological relationshipsPublication . Mendes, Susana; Fernández-Gómez, M. José; Pereira, Mário Jorge; Azeiteiro, Ulisses Miranda; Galindo-Villardón, M. PurificaciónThe wide-ranging and rapidly evolving nature of ecological studies mean that it is not possible to cover all existing and emerging techniques for analyzing multivariate data. However, two important methods enticed many followers: the Canonical Correspondence Analysis (CCA) and the STATICO analysis. Despite the particular characteristics of each, they have similarities and differences, which when analyzed properly, can, together, provide important complementary results to those that are usually exploited by researchers. If on one hand, the use of CCA is completely generalized and implemented, solving many problems formulated by ecologists, on the other hand, this method has some weaknesses mainly caused by the imposition of the number of variables that is required to be applied (much higher in comparison with samples). Also, the STATICO method has no such restrictions, but requires that the number of variables (species or environment) is the same in each time or space.Yet, the STATICO method presents information that can be more detailed since it allows visualizing the variability within groups (either in time or space). In this study, the data needed for implementing these methods are sketched, as well as the comparison is made showing the advantages and disadvantages of each method. The treated ecological data are a sequence of pairs of ecological tables, where species abundances and environmental variables are measured at different, specified locations, over the course of time.
- Immobilized heterologous Rhizopus oryzae lipase: A feasible biocatalyst for the production of human milk fat substitutesPublication . Tecelão, Carla; Guillén, Marina; Valero, Francisco; Ferreira-Dias, SuzanaThis work aims at evaluating the potentialities of a heterologous Rhizopus oryzae lipase (rROL) as a feasible biocatalyst, to be used as an alternative to commercial lipases, for the synthesis of Human Milk Fat Substitutes (HMFS). This enzyme was immobilized in three different supports (Accurel® MP 1000, Eupergit® C and Lewatit® VP OC 1600) and tested as catalysts for the acidolysis between tripalmitin and oleic acid, batchwise, at 60 ◦C, in solvent-free medium. The highest molar incorporations of oleic acid in the triacylglycerols were achieved with rROL in Lewatit® VP OC 1600 and Accurel® MP 1000, although the highest immobilization yields were observed with Eupergit® C. Quasi-equilibrium was attained after 6 h or 12 h reaction, with about 30 mol.% and 22 mol.% of oleic acid incorporation, when rROL immobilized in Lewatit and Accurel were used, respectively. Also, 23 h batch operational stability tests were performed: half-life times (t1/2) of 34.5 h and 64.0 h were achieved for rROL immobilized in Accurel® MP 1000 and in Lewatit® VP OC 1600, respectively. An important increase in the operational stability was observed for rROL immobilized in Lewatit after rehydration at the end of each batch (t1/2 = 202 h). Thus, the loss of activity may be explained by a progressive dehydration occurring along the reaction.