Growing tissues exhibit liquid-like behavior, which allows them to respond to macroscopic surface curvatures.

Motivated by often contradictory literature reports on the dependence of the surface energy of gold nanoparticles on the variety of its size and shape, we performed an atomistic study combining molecular mechanics and ab initio calculations. We show that, in the case of Au nanocubes, their surface energy converges to the value for $\left(001\right)$ facets of bulk crystals. A fast convergence to a single valued surface energy is predicted also for nanospheres. However, the value of the surface energy is larger in this case than that of any low-index surface facet of bulk Au crystal. This fact can be explained by the complex structure of the surface with an extensive number of broken bonds due to edge and corner atoms. A similar trend was obtained also for the case of cuboctahedrons. Since the exact surface area of the nanoparticles is an ill-defined quantity, we have introduced the surface-induced excess energy and discuss this quantity as a function of (i) number of atoms forming the nano-object or (ii) characteristic size of the nano-object. In case (i), a universal power-law behaviour was obtained independent of the nanoparticle shape. Importantly, we show that the size-dependence of the surface energy is hugely reduced, if the surface area correction is considered due to its expansion by the electronic cloud, a phenomenon specifically important for small nanoparticles.

The role of several sorts of traps for one diffusing interstitial component is investigated. The site fraction of this component in each trap is calculated due to the local thermodynamic equilibrium condition with its site fraction in the lattice. Combining Fick's first law for diffusive fluxes of individual site fractions with the equilibrium condition and the mass balance allows deriving an extended nonlinear diffusion equation. If the molar volumes of the trap positions are constant with respect to time, then a generalized chemical diffusion coefficient can be derived, which allows performing the diffusion study in terms of the total concentration of the interstitial component. As an alternative way, the total diffusion flux can also be treated as the sum of diffusion fluxes of individual fractions combined with local redistribution of individual fractions based on the thermodynamic local equilibrium condition. Both concepts are presented in simulations for the diffusion of hydrogen in the system with traps as immobile dislocations, substitutional impurities and interfaces of incoherent carbide nanoprecipitates. Both concepts provide equivalent results and exhibit an asymmetric behaviour with respect to a charging/discharging process.

Long free strips of small thickness frequently show a wavy surface being the consequence of buckling due to residual stresses. The paper deals with the derivation of the corresponding relations under conditions which are frequently met in the case of edge wave buckling of rolled strips or in deployable structures. It is shown that an increasing global tension force does not only lead to increased critical residual stress intensity but also produces shorter buckling waves concentrated towards the edges of the strip. By introducing dimensionless quantities, diagrams and formulas are provided which allow the determination of critical loading combinations. Asymptotic considerations are also presented.