2014 It is shown that in nematic liquid crystals the disclinations which are attached to the external boundaries of the specimens can be described by a Peierls-Nabarro type model known from the theory of crystal dislocations. Mathematically, dislocations with planar cores and surface disclinations are then completely analogous if the isotropic one-constant approximation and a planar distributio...

The present paper explores quasi-cleavage processes driven by dislocation pileups against a Dislocation Free Zone (DFZ). The nanoscopic growth of the main crack consists of sequences of nanocrack formation in DFZ and its subsequent linkage with the main crack. Under mode I loading, the equilibrium locations of individual dislocations and the equilibrium number of dislocations are determined by ...

We use a nondestructive technique of fluorescence confocal polarizing microscopy to visualize three-dimensional director patterns of defects in Grandjean-Cano wedges filled with a cholesteric liquid crystal of pitch p=5 microm. Strong surface anchoring of the director causes a stable lattice of dislocations in the bulk. Optical slicing in the vertical cross sections of the wedges allows us to e...

absractall perilunate fracture-dislocations combine bone avulsions, ligament disruptionand fractures in different forms. the most frequent pattern is the dorsal transscaphoidperilunate fracture-dislocation. the reported risk of missed initial diagnosisin perilunate dislocations is as high as 20%. concerning pathomechanics of theperilunate fracture-dislocation, it should be noted that most dorsa...

The concept of a spherically symmetric second-rank tensor field is formulated. A general representation such derived. Results related to analysis fields and their geometric properties are presented. Using these results, formulation the problem nonlinear theory dislocations given. For an isotropic elastic material with arbitrary distribution dislocations, this reduced boundary value for system o...

GaN films are grown by plasma-assisted molecular beam epitaxy on 6H-SiC(0001) substrates. Suitable substrate preparation and growth conditions are found which greatly improve the structural quality of the films. Threading dislocation densities of about 1 10 cm for edge dislocations and 1 10 cm for screw dislocations are achieved in GaN films of 1 m thickness grown under optimal conditions. Reve...

ÐThe e€ect of hydrogen on the interaction between dislocations and other elastic centers (impurity atoms and dislocations) in 310 S stainless steel and high-purity aluminum has been directly observed during deformation experiments in situ in an environmental cell transmission electron microscope. In 310 S stainless steel, the presence of hydrogen was observed to reduce the elastic interactions ...