Dislocation and grain-boundary processes contribute significantly to plastic behaviour in polycrystalline metals, but a full understanding of the interaction between these processes and their influence on plastic response has yet to be achieved. The coupled atomistic discrete-dislocation method is used to study edge dislocation pile-ups interacting with a 11-1 1 3 symmetric tilt boundary in Al at zero temperature under various loading conditions. Nucleation of grainboundary dislocations (GBDs) at the dislocation/grain-boundary intersection is the dominant mechanism of deformation. Dislocation pile-ups modify both the stress state and the residual defects at the intersection, the latter due to multiple dislocation absorption into the boundary, and so change the local grain-boundary/dislocation interaction phenomena as compared with cases with a single dislocation. The deformation is irreversible upon unloading and reverse loading if multiple lattice dislocations absorb into the boundary and damage in the form of microvoids and loss of crystalline structure accumulates around the intersection. Based on these results, the criteria for dislocation transmission formulated by Lee, Robertson and Birnbaum are extended to include the influences of grain-boundary normal stress, shear stress on the leading pile-up dislocation and minimization of step height at the intersection. Two possible yield loci for the onset of GBD nucleation versus compressive stress and relevant shear stresses are derived from the simulations. These results, and similar studies on other boundaries and dislocation characters, guide the formulation of continuum constitutive behaviours for use in discrete-dislocation or strain-gradient plasticity modelling.

The aspects of application of the hollow core photonic crystal waveguides for spectroscopic analysis of liquid medium were considered. The possibility of using these structures for analysis of a fruit juice was evaluated. The principles of processing of photonic crystal waveguide transmission spectra, which is sensitive to quality of juice, its composition, and main component concentration, were revealed.

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The hollow core photonic crystal waveguide biosensor is designed and described. The biosensor was tested in experiments for arti¯cial sweetener identi¯cation in drinks. The photonic crystal waveguide biosensor has a high sensitivity to the optical properties of liquids¯lling up the hollow core. The compactness, good integration ability to di®erent optical systems and compatibility for use in industrial settings make such biosensor very promising for various biomedical applications.

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