A study on coherency strain and precipitate morphology via a discrete atom method

Morphological evolution of coherent precipitates is studied by means of a discrete atom method under a plane strain condition with a purely dilatational misfit. The method is predicated upon Hookean atomic interactions and Monte Carlo diffusion and makes no assumption of a specific precipitate shape. Precipitates having elastic constants different from those of the matrix phase are treated in both isotropic and anisotropic elastic systems. Shape evolution is examined under the condition of a constant precipitate size and an isotropic interfacial energy. The results show that in general, an elastically soft precipitate tends to have an equilibrium morphology of low symmetry such as a plate, whereas a hard particle tends to take up a shape of high symmetry such as a circle. Morphological evolution proceeds through dynamic activities of coherency-induced interfacial waves whose wavelength depends upon the difference in-elastic constants, precipitate geometry, anisotropy, and diffusion temperature. Coherency-induced interfacial waves seem to be responsible for the protrusions often observed along elastically hard directions in y particles of Ni-base superalloys and also to be a source for fresh ledges for growth via the ledge mechanism. For a highly nonequilibrium precipitate, first splitting followed by coalescence appears to be a common feature in achieving its equilibrium morphology

Meio de cultura, concentração de AIB e tempo de cultivo no enraizamento in vitro de amoreira-preta e framboeseira Culture environment, IBA concentration and cultivation time on in vitro rooting of blackberry and raspberry

A propagação da amoreira-preta e da framboeseira dá-se principalmente por meio de estacas de raiz e mesmo de hastes novas, contudo, já é crescente o interesse pelo uso da micropropagação como um método alternativo de propagação . O enraizamento é uma das etapas mais difícieis, onde a definição do meio de cultivo, da concentração ótima de AIB para o enraizamento, constitui um passo importante, por isso objetivou-se com este experimento determinar o melhor meio de cultivo, melhor tipo de cultivo e a melhor concentração de AIB no meio de cultura para o enraizamento in vitro da amoreira-preta 'Xavante' e de framboeseira 'Batum' e 'Heritage'. O material vegetal utilizado foram microestacas apicais com duas folhas, com cerca de 1 cm de comprimento, oriundas do cultivo in vitro. Os fatores estudados foram o tipo de meio de cultura MS e WPM - Wood Plant Media, a concentração de AIB no meio de cultura e o tempo de cultivo das microestacas em meio com AIB. O meio WPM, em concentrações baixas, menores de 3 µM de AIB, induziram maiores médias de enraizamento e comprimento. Concentrações altas de AIB induziram a formação de calo, para amoreira-preta, 'Xavante'. Para a framboeseira o meio WPM, com menores concentrações de AIB (0 e 3 µM), mostrou as melhores médias no número de raízes, comprimento de raízes e pequena intensidade de calo; com as maiores concentrações de AIB, ocorreu maior aparecimento de calo.<br>The propagation of blackberry and raspberry occur mainly through root cutting and even of softwoods stem; however, it is already increasing the interest for the use of the micropropagation as an alternative technique of vegetative propagation of fruit plants, since the rooting is one of the most difficult stages, in which the definition of both the culture environment and the best concentration of AIB for the rooting, is an important stage. For that purpose, the aim of this research was to determine the best cultivation type and the best concentration of IBA in the culture environment for the in vitro rooting of the blackberry 'Xavante' and the raspberry 'Batum' and 'Heritage'. The vegetable material used was atex microcutting with two leaves, measuring about 1 cm of length, originated from the in vitro cultivation. The studied factors were the kinds of culture (MS and WPM), the IBA concentration in the culture environment and the time of cultivation of the microcutting in an environment with IBA. The WPM environment, in low concentrations, less than 3 µM of IBA, together with T1, induced larger rooting averages and length. High concentrations of AIB induced the callus formation for blackberry 'Xavante'. For raspberry, using WPM environment with smaller concentrations of AIB (0 and 3 , µM), it was shown the best average in the number of roots, length of roots and small callus intensity, with the largest concentrations of IBA it happened larger callus emergence

Influence of supplemental maslinic acid (olive-derived triterpene) on the post-mortem muscle properties and quality traits of gilthead seabream

Maslinic acid, a natural triterpene, was evaluated as a dietary supplement to modulate glycogen post-mortem mobilization in gilthead seabream muscle. For this purpose, a multidisciplinary trial was undertaken, where flesh quality criteria, as well as biochemical and histological parameters, enzymatic activities and protein expression in the muscle were assessed. Supplementing gilthead seabream diets with maslinic acid mainly resulted in hypertrophy of muscle fibres and inhibition of cathepsin B activity, with no observed differences in terms of glycogen and ATP content of the muscle, as well as glycogen phosphorylase activity. Proteomic analysis showed a low impact of maslinic acid supplementation on muscle metabolism, with most changes reflecting increased stress coping capacity and muscle hypertrophy in maslinic acid-fed fish. As a finishing strategy to improve the muscle's energetic status, the usefulness of maslinic acid seems limited. However, it shows potential for promoting muscle growth in this species