We formulate a variational model for a geometrically necessary screw dislocation in an anti-plane lattice model at zero temperature. Invariance of the energy functional under lattice symmetries renders the problem non-coercive. Nevertheless, by establishing coercivity with respect to the elastic strain and a concentration compactness principle, we prove existence of a global energy minimiser an...

We use a family of embedded atom model potentials all based on accurate quantum-mechanical calculations to study the relation between Peierls stress and core properties of the 1/2a^111& screw dislocation in bcc tantalum ~Ta!. We find that the Peierls stress (sP) is a function of the core-polarization curvature ~P! near the equilibrium core configuration. Our results suggest that the computation...

Cannulated hip screws (CHS) can be used for the minimally invasive fixation of non-dislocated femoral neck fractures. Usually, three are inserted. This study aims to determine whether by two CHS leads similar results as CHS. Since January 2019, all patients with an indication internal were treated and followed prospectively. Results compared equal-sized control group who underwent (before 2019)...

Posterior fracture-dislocation of hip is uncommonly encountered in rugby injuries. We report such a case in an adult while playing rugby. The treating orthopaedician can be caught unaware and injuries in such sports can be potentially misdiagnosed as hip sprains. Immediate reduction of the dislocation was performed in theatres. The fracture was fixed with two lag screws and a neutralization pla...

We performed a retrospective study of the factors affecting the outcome of Weber type-C ankle fractures in 43 patients reviewed at two to nine years after injury. We determined the functional result in relation to the use of a diastasis screw, the accuracy of reduction, the presence of tibiotalar dislocation, and of injury to the medial side of the ankle by medial malleolar fracture or deltoid ...

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...

We report on the metalorganic vapor phase epitaxial (MOVPE) growth of AlN films on sapphire substrates. The effect of precursor flow rate and nucleation layer (NL) on the film quality was investigated. The films were characterized using AFM, XRD and PL. We could realize AlN films with very smooth surfaces and narrow symmetric XRD peaks indicating low screw/mixed type dislocation densities in th...