CIMO - Artigos em Revistas Indexados à WoS/Scopus
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- Relationships between fat depots and body condition score or tail fatness in Rasa Aragonesa breedPublication . Teixeira, Alfredo; Delfa, Rafael; Colomer-Rocher, F.The relationships between body fat depots and body condition score (BCS) were determined in 52 adult Rasa Aragonesa ewes aged 10 (s.d. 2) years and ranging in BCS from 1-5 to 4•5. BCS of each ewe was assessed by three people. the repeatability within individual being 90"/0 and between individuals 80%. The ewes were weighed before slaughter. After slaughter the omental mesenteric kidney and pelvic fat were separated and weighed. The fat of the left side of the carcass was separated into subcutaneous and intermuscular depots. The relationship between live weight and BCS was semilogarithmic and those between fat depots and BCS were logarithmic. Regression analysis was also used to describe the relationships between the various fat depots and BCS or live weight Of the variation in total fat weight. proportionately 0•90 was accounted for by variations in BCS while 0•84 was accounted for by variations in live weight. For individual fat depots proportionately 0•86 to 0•90 of the variation was accounted for by variation in BCS and 0•69 to 0-79 by variation in live weight. BCS was a better predictor than live weight of the weight of both total body fat and the individual fat depots. A curvilinear regression between BCS and live weight showed that the increases in live weight for a unit change in BCS was 7, 10, 12 and 16 kg for each one point increase ill BCS from 1 to 5 respectively. The tail fat depot (tail fatness score) •Was assessed in the same ewes by score on a three-point scale. Of the variation in the weight of individual fat depots proportionately 0•79 to 0•86 was accounted for by variation in tail fatness score. Thus the tail fatness score could be used as an additional method of assessing body condition in the Aragonesa breed.
- Experimental determination of sequence length distribution of hard segments in polyester-polyurethanesPublication . Barreiro, M.F.; Dias, Rolando; Costa, Mário RuiA new analytical procedure based on selective acid hydrolysis was developed to measure the chain length distribution of hard segments (HSCLD) of polyester-polyurethanes. It was tested with polymers made from 4,4'-methylenebis(pheny1 isocyanate), 1,6-hexanediol, and a,w-dihydroxypoly- (hexamethylene adipate) with number-average molecular weight 2200. Heating samples with 0.25 M HC1 solution in dimethyl sulfoxide with 8.2% water for 36 h leads to nearly complete hydrolysis of the ester groups, leaving the urethanes largely unaffected. The resulting mixture of oligomers can be analyzed by size exclusion chromatography, using dimethylformamide at room temperature as the solvent. Experimentally measured HSCLDs were most often very different from those theoretically predicted for homogeneous reaction.
- A general kinetic analysis of non-linear irreversible copolymerizationsPublication . Costa, Mário Rui; Dias, RolandoIrreversible non-linear copolymerizations with arbitrarily great numbers of monomers are described specifying the stoichiometric coefficients of the reactions involving end-groups. Rate equations for the vectorial generating function or discrete transform of the distribution of end-groups and repeating units and its derivatives with respect to logarithms of Laplace parameters can thus be written. Similar rate equations can be written for the discrete transforms of the distributions of descendants of each linking group with respect to their numbers of end-groups. This allows the prediction of gel properties, such as the concentration of elastically active network chains and mass fraction of pendant material. Mass balance equations using these rate laws are non-linear partial differential equations solvable by the method of characteristics. Numerical methods are developed for computing molecular weight distributions and average molecular weights before and after gelation, as well as the weight fraction of sol ang gel properties related to its elasticity behaviour. The curing of a tetraepoxide with a primary diamine is taken as a case study and results are compared with predictions by the theory of branching processes.
- Representation of solubilities of amino acids using the UNIQUAC model for electrolytesPublication . Peres, António M.; Macedo, Eugénia A.A molecular thermodynamic framework for the representation of the solubilities of several binary systems, amino acids-water (nine systems) and peptides-water (five systems), has been developed and tested. The proposed model takes into account simultaneously the chemical and physical equilibrium. The latter is described by the UNIQUAC model combined with a Debye-Huckel term. Molal activity coefficient data from the literature were used in order to estimate the new UNIQUAC parameters. These parameters, together with solubility data, were the basis for the correlation of the solubility product of the different amino acids considered in this work. With this approach, very satisfactory results have been obtained for the representation and prediction of the solubilities of amino acids in water as a function of both temperature and pH.
- Solubility of amino acids: a group-contribution model involving phase and chemical equilibriaPublication . Pinho, Simão; Silva, Carlos M.; Macedo, Eugénia A.A new model is proposed to represent the solubility behavior of 14 amino acids and 5 small peptides in water. The UNIFAC model is combined with a Debye-Huckel term to describe the activity coefficients of the species present in the biomolecule/water system. New groups have been defined according to the group-contribution concept, and chemical equilibrium is taken into account simultaneously with the physical equilibrium. To estimate the new interaction parameters, molal activity coefficient data from the literature were used. These parameters, in addition to solubility data, were the basis for the correlation of the solubility product of the amino acids. Using this approach, satisfactory results were obtained in the representation and prediction of the solubilities of amino acids in aqueous solutions at different conditions of temperature and pH.
- Effects of rock fragments on physical degradation of cultivated soils by rainfallPublication . Van Wesemael, Bas; Poesen, Jean; Figueiredo, Tomás deTo understand better the role of rock fragments in soil and water conservation processes, the effects of rock fragments in maintaining a favourable soil structure and thus also in preventing physical degradation of tilled soils was studied. Laboratory experiments were conducted to investigate the effects of rock fragment content, rock fragment size, initial soil moisture content of the fine earth and surface rock fragment cover on soil subsidence by rainfall (i.e. change in bulk density by one or more cycles of wetting and drying). A total of 15 rainfall simulations (cumulative rainfall, 192.5 mm; mean intensity, 70 mm h−1) were carried out. Before and after each rainfall application the surface elevation of a 19-cm thick plough layer was measured with a laser microrelief meter. In all experiments, the bulk density of the fine earth increased with applied rainfall volume to reach a maximum value at about 200 mm of cumulative rainfall. From the experimental results it was concluded that the subsidence rate decreased sharply for soils containing more than 0.50 kg kg−1 rock fragments, irrespective of rock fragment size. Fine earth bulk densities were negatively related to rock fragment content beyond a threshold value of 0.30 kg kg−1 for small rock fragments (1.7–2.7 cm) and 0.50 kg kg−1 for large rock fragments (7.7 cm). Initial soil moisture content influenced subsidence only in the initial stage of the experiments, when some swelling occurred in the dry soils. Surface rock fragment cover had no significant effect on subsidence of the plough layer. Therefore, subsidence of the plough layer in these experiments appears to be mainly due to changing soil strength upon drainage rather than the result of direct transfer of kinetic energy from falling drops. The relative increase in porosity of the fine earth as well as the absolute increase in macroporosity with rock fragment content will cause deeper penetration of rainfall into the soil, resulting in water conservation. Therefore, crushing of large rock fragments into smaller ones is to be preferred over removal of rock fragments from the plough layer.
- Growth and development of Serrana kids from Montesinho Natural Park (NE of Portugal)Publication . Teixeira, Alfredo; Azevedo, Jorge; Delfa, Rafael; Morand-Fehr, Pierre; Costa, Cléber Thiago FerreiraThis study was to evaluate meat potential of Serrana goats, raised under harsh conditions of the mountains of NE Portugal. Sixteen males of the local Serrana goat breed were taken from different herds in Montesinho Natural Park in NE Portugal. Allometric coefficients of different body tissues and carcass were calculated. Shoulder and leg were earlier developing than loin and breast. Muscle was isometric (b = 1.07; P 2 0.05) and bone was the most precocious tissue (b = 0.763; PI 0.01). Different fat deposits were later developing, with allometric coefficients (PI 0.01) higher than 1 .O, and the order of fat deposition was: subcutaneous fat, intermuscular fat, mesenteric fat, kidney knob and channel fat (KKCF - the perinephric and retroperitoneal fat) and omental fat. Subcutaneous and intermuscular fat deposits, which were later developing in relation to BW, were isometric in relation to total fat of carcass. All fat deposits in the different carcass joints (with the exception of fat deposits in leg and shoulder and the subcutaneous fat in loin and neck) had allometric coefficients (PsO.01) higher than 1.0. Sites of the later subcutaneous fat deposition were breast and chump, whereas later intermuscular fat depositions were in loin and breast. The results suggest that intermuscular fat is later developing than subcutaneous fat in relation to half carcass weight. The higher proportion of muscle and lower proportion of subcutaneous and intermuscular fat deposits indicate the potentialities of the Serrana breed as a source of lean meat, according to the consumption preferences of the Mediterranean area of the European Union.
- Separation of enantiomers of 1a,2,7,7a-tetrahydro-3-methoxynaphtha-(2,3b)-oxirane by liquid chromatography: laboratory-scale elution chromatography and modelling of simulated moving bedPublication . Rodrigues, Alírio; Lu, Z.P.; Loureiro, José M.; Pais, Luís S.The separation of enantiomers of la,2,7,7a-tetrahydro-3-methoxynaphtha-(2,3b)-oxirane (Sandoz epoxide) on cellulose triacetate HPLC columns was investigated on the laboratory scale. The performance of the columns was calculated by HEPT measurements and the slopes of the adsorption equilibrium isotherms and effective diffusivities were calculated from elution chromatographic experiments. Multi-component adsorption equilibrium isotherms were calculated from single isotherms by using the ideal adsorbed solution (IAS) model. Simulation of continuous chromatographic separation of the racemic mixture of Sandoz epoxide in a simulated moving bed was carried out and the effect of mass transfer coefficient on process performance was analysed.
- Riparian ecotones and spatial variation of fish assemblages in Portuguese lowland streamsPublication . Collares-Pereira, M.J.; Geraldes, Ana Maria; Magalhães, M.F.; Coelho, Maria M.The first results of a long-term study on the role of riparian ecotones on the population and community dynamics of Iberian stream fish are presented and discussed . Riparian and macrophyte cover, bank slope and depth were among the most important variables affecting fish distribution . In general small fish favoured shallow areas with high macrophyte cover, whereas large fish dominated in deep areas with a high riparian cover . Slight spatial changes in terrestrial prey use were found suggesting a minor role for this resource during autumn . Finally, no significant spatial differences were found for linear growth, although some differences were obtained for the condition factor
- Preliminary insight into age and growth of the Iberian chub (Leuciscus pyrenaicus) in the sorraia systemPublication . Geraldes, Ana Maria; Collares-Pereira, M.J.An investigation of age and growth in the Iberian chub Leuciscus pyrenaicus Gunther, 1868 revealed a seasonal growth pattern, with annulus formation restricted to a short period of the year (May/June). Maximum ages were 6+ for both sexes. During and after the third year females grew at faster rates than males, and the most important decrease in growth rates occurred between age I! and Ill in males and between age Ill and IV in females. Mean back-calculated standard lengths of III and IV age classes were significantly higher in the River Sorraia. Mean weights of I and II age classes were higher in Sor stream whereas the individuals from III ad IV age classes were heavier in the River Sorraia. Shifts in growth rates arc discussed in relation to seasonal and spatial variations in the environmental conditions as well as to sexual maturity.