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Innovative design through colour has always been a very important feature in decorative items, jewellery inclusive. The use of coloured gold alloys (e.g. red, white, green) in the manufacture of jewellery artifacts is nowadays generalized, and one can often see jewellery items that combine more than a single colour. However, multi-coloured jewellery artifacts are generally made of parts produced separately and bonded together in a later step. The ability to produce jewellery sub-components or final pieces using a powder metallurgy process aimed at producing innovative multi-coloured gold jewellery items with colour gradients is explored in this paper. Four 19.2 ct coloured gold powders (yellow, green, red and white) were hot pressed at different times and temperatures and the resulting samples were analyzed in terms of their microstructure, hardness, porosity, microstructure and optical properties. A manufacturing route to obtain multi-coloured jewellery pieces with colour gradients is also presented. Keywords Gold alloys. Powder metallurgy. Hot pressing. Optical properties. Microstructure. Hardness, Introduction Gold and gold alloys have been for ages the metal of choice for jewellery manufacturing. The jewellery items are classified in terms of gold content, described in terms of [...]

Population structure and genetic diversity in the Portuguese native breeds of pigs Alentejano (AL), Bisaro (BI), and Malhado de Alcobaca (MA) and the exotic breeds Duroc (DU), Landrace (LR), Large White (LW), and Pietrain were analyzed by typing 22 microsatellite markers in 249 individuals. In general, the markers used were greatly polymorphic, with mean total and effective number of alleles per locus of 10.68 and 4.33, respectively, and an expected heterozygosity of 0.667 across loci. The effective number of alleles per locus and expected heterozygosity were greatest in BI, LR, and AL, and least in DU. Private alleles were found in 9 of the 22 markers analyzed, mostly in AL, but also in the other breeds, with the exception of LW. The proportion of loci not in Hardy-Weinberg equilibrium in each breed analyzed ranged between 0.23 (AL) and 0.41 (BI, LW, and Pietrain), mostly because of a less than expected number of heterozygotes in those loci. With the exception of MA, all breeds showed a significant deficit in heterozygosity ([F.sub.IS]; P < 0.05), which was more pronounced in BI ([F.sub.IS] = 0.175) and AL ([F.sub.IS] = 0.139), suggesting that inbreeding is a major concern, especially in these breeds that have gone through a genetic bottleneck in the recent past. The analysis of relationships among breeds, assessed by different methods, indicates that DU and AL are the more distanced breeds relative to the others, with the closest relationship being observed between LR and MA. The degree of differentiation between subpopulations ([F.sub.ST]) indicates that 0.184 of the total genetic variability can be attributed to differences among breeds. The analysis of individual distances based on allele sharing indicates that animals of the same breed generally cluster together, but subdivision is observed in the BI and LR breeds. Furthermore, the analysis of population structure indicates there is very little admixture among breeds, with each one being identified with a single ancestral population. The results of this study confirm that native breeds of pigs represent a very interesting reservoir of allelic diversity, even though the current levels of inbreeding raise concerns. Therefore, appropriate conservation efforts should be undertaken, such as adopting strategies aimed at minimizing inbreeding, to avoid further losses of genetic diversity. Key words: diversity, genetic variability, microsatellite, native breed, pig

Byline: L. Mazare, G. Miranda, D.F. Soares, F.S. Silva This paper is concerned in assessing the possibility of the use of a Directional Solidification (DS) process in order to produce functionally graded materials. It will be assessed the influence of the relative displacement rate between heating coil and mould, in order to evaluate the produced cooling rates along the casting and consequent metallurgical and mechanical properties on the obtained component. A copper-silver alloy, which is prompt to macro-segregation occurrence, will be used. Results demonstrate that the process, which is able to originate DS castings, may also be used for FGMs production.

Byline: G. Chirita, I. Stefanescu, D.F. Soares, F.S. Silva This paper deals with the study of the centrifugal effect on aluminum castings under high G values. In this study it will be shown that aluminum alloys, without reinforcement, and where there is almost no difference of density or low solubility of different phases, may also give rise to a Functionally Graded Material – FGM. It seems that the main variable that affects the mechanical and metallurgical properties is the fluid dynamics of the process.