[en] Cellular growth and dendritics in samples of Zn-Cd, of compact hexagonal crystallography, are strongly influenced by the direction of crystalline growth. The literature [O. Fornaro, H. Palacio: Scripta Materialia 54 (2006) 2149], shows that the critical values of the V_c velocity and the length of the characteristic λC wave during the transition from flat to cellular, displays different values depending on the crystalline direction. This influence, however, is not considered during the description of the transition from flat to cellular. Single directional growths with the Zn-0.01, 0.05 and 0.1 %Cd system have been developed using a Bridgman system, in the zone corresponding to the flan-cellular phase, showing this dependence experimentally. A modified version of the Morphological Stability Theory that introduces the angular functionality of the surface energy in the stable condition was used in order to explain the behavior observed. The theoretical analysis shows that after introducing an angular dependence in the free interfacial energy, a displacement appears in the critical and primary spacings and in the critical V_c speed, but these results are observed less than those observed experimentally (CW)

[en] In this note, we will generalize the notion of separation index, which was introduced by Manjunath et al. (2006), to dendrite maps, and use the notion to characterize the intra-orbit separation for the orbits of continuous transitive dendrite maps. We will show: (i) For a dendrite map f, the separation index γ is greater than zero if and only if the set of fixed points of f is not an arc connected subspace. (ii) If the separation index γ of a dendrite map f is greater than zero, then for every 0<τ<γ and any pair of distinct points x and y on a dense orbit, {x,y} is a Li–Yorke pair of modulus τ

No abstract available

[en] Dendritic cells are key regulators in directing immune responses and therefore are under extensive research for the induction of anti-tumor responses. DCs express a large array of receptors by which they scan their surroundings for recognition and uptake of pathogens. One of the receptor-families is the C-type lectins (CLR), which bind carbohydrate structures and internalize antigens upon recognition. Intracellular routing of antigen through CLR enhances loading and presentation of antigen through MHC class I and II, inducing antigen-specific CD4"+ and CD8"+ T-cell proliferation and skewing T-helper cells. These characteristics make CLRs very interesting targets for DC-based immunotherapy. Profound research has been done on targeting specific tumor antigens to CLR using either antibodies or the natural ligands such as glycan structures. In this review we will focus on the current data showing the potency of CLR-targeting and discuss improvements that can be achieved to enhance anti-tumor activity in the near future

[en] We summarize recent advances in modeling of solidification microstructures using computational methods that bridge atomistic to continuum scales. We first discuss progress in atomistic modeling of equilibrium and non-equilibrium solid-liquid interface properties influencing microstructure formation, as well as interface coalescence phenomena influencing the late stages of solidification. The latter is relevant in the context of hot tearing reviewed in the article by M. Rappaz in this issue. We then discuss progress to model microstructures on a continuum scale using phase-field methods. We focus on selected examples in which modeling of 3D cellular and dendritic microstructures has been directly linked to experimental observations. Finally, we discuss a recently introduced coarse-grained dendritic needle network approach to simulate the formation of well-developed dendritic microstructures. The approach reliably bridges the well-separated scales traditionally simulated by phase-field and grain structure models, hence opening new avenues for quantitative modeling of complex intra- and inter-grain dynamical interactions on a grain scale

[en] The hydrodynamic radii (R_η) calculated from intrinsic viscosities of poly(amido amide) (PAMAM) starburst dendrimers increasing generation number. This would seem to support a structure with strongly stretched tiers, which is relatively hollow near the core, and with most end groups near the surface. However, a computer simulation due to Lescanec and Muthukumar supports a more folded structure with higher density near the core and with end groups dispersed throughout the molecule. Here we calculate the hydrodynamic radii of the Lescanec-Muthukumar model using intrinsic viscosity formulas developed by Zimm and Fixman. The Lescanec-Muthukumar starbursts with relatively stiff spacers have hydrodynamic radii in good agreement with the experimental PAMAM radii, in spite of their folded structure. The hydrodynamic radius is sensitive both to the molecular size and to the density. As the number of generations increases, the molecules become more dense and the hydrodynamic radius increases more rapidly than the radius of gyration. 16 refs., 7 figs., 2 tabs

[en] The primary dendrite arm spacing (PDAS) is one of the main characteristic parameters of directionally solidified dendritic structures. It is widely used to characterise as-cast structures and to correlate them with the local solidification conditions. Although, common use seems to refer to a unique relationship between solidification conditions and PDAS, it has been widely accepted that there exists a distribution of spacings in a dendritic array. In the present work a novel method for the determination of the PDAS is proposed, which yields the average PDAS, its distribution and the number of nearest neighbours. These quantities - which can be used to characterise dendritic arrays - are obtained by determining the centre of gravity of all dendrites in the array under consideration and then applying a specially designed algorithm to identify the nearest neighbours of each dendrite. The characteristics of the method are demonstrated by applying it to test structures and dendritic structures obtained from directional solidification experiments.

[en] A phase-field formulation is introduced to simulate quantitatively microstructural pattern formation in alloys. The thin-interface limit of this formulation yields a much less stringent restriction on the choice of interface thickness than previous formulations and permits one to eliminate nonequilibrium effects at the interface. Dendrite growth simulations with vanishing solid diffusivity show that both the interface evolution and the solute profile in the solid are accurately modeled by this approach

No abstract available

[en] In this paper, the morphological transition from dendrite to symmetry-broken dendrite is investigated in the directional solidification of non-axially-oriented crystals using a quantitative phase-field model. The effects of pulling velocity and crystal orientation on the morphological transition are investigated. The results indicate the orientation dependence of the symmetry-broken double dendrites. A dendrite to symmetry-broken dendrite transition is found by varying the pulling velocity at different crystal orientations and the symmetry-broken multiple dendrites emerge as a transition state for the symmetry-broken double dendrites. The state region during the transition can be well characterized through the variations of the characteristic angle and the average primary dendritic spacing