The dislocation distribution of high-quality single-crystal gallium nitride (GaN) films grown by the hybrid vapor phase epitaxy was analyzed. This study examined the domain structure of GaN from the dislocation distribution on the macroscale by optical microscopy. The surface structure of GaN consisted of domains with microcolumns as the substructure. The inner domains contained a lower density...

Plastic deformation mediated by collective dislocation dynamics is investigated in the two-dimensional phase-field crystal model of sheared single crystals. We find that intermittent fluctuations in the dislocation population number accompany bursts in the plastic strain-rate fluctuations. Dislocation number fluctuations exhibit a power-law spectral density 1/f2 at high frequencies f. The proba...

Abstract The current study reports three different techniques to estimate the distribution of dislocation density at mid thickness 1050 Al alloy. It is well known that strain inhomogeneous through rolled materials, which affects evolution during process deformation. In this study, number dislocations was calculated experimentally using indentation technique in 46.8% cold sheet and result verifi...

Mok Ka Leung, FHKCEM Kan Pui Gay, FHKCEM Wong Yau Tak, FHKCEM We describe the ultrasound evaluation technique and sonographic findings of a case of anterior shoulder dislocation. The sonographic features of anterior shoulder dislocation include: "sign of widening of subacromial space", "sign of disappearance of humeral head", "artery/vessel sign", "humeral head below coracoid process sign" and ...

Dislocation of the sternoclavicular joint is a rare injury and typically requires high-energy forces applied through the joint. Initial treatment is dependent on the direction of dislocation, with acute reduction indicated for posterior dislocations presenting with signs of tracheal, esophageal, or neurovascular compression. Although most patients do well with conservative treatment after the i...

It is accepted that a traumatic hip dislocation is a surgical emergency, this holds for the uncommon dislocation of the hip with femoral neck fracture however the surgical dilemma involves head salvage or replacement. This case report describes the method and technique for stabilisation of the rare and challenging isolated posterior hip dislocation with an ipsilateral femoral neck fracture. A 3...

Size effects at initial yield (prior to stage II) of idealized micron-sized specimens are modeled within a continuum model of plasticity. Two different aspects are considered: specification of a density of dislocation sources that represent the emission of dislocation dipoles, and the presence of an initial, spatially inhomogeneous excess dislocation content. Discreteness of the source distribu...

Two cases of the severe fracture-dislocation of the cervical spine with tetraplegia have been treated successfully with a new technique. This technique consists of anterior vertebral body fusion with a tibia span added to the Cloward's method. This procedure permitted substantial removal of ruptured disks and bone fragments, effectivelly strengthened the spine weakened by fracture, and also ena...

The present paper deals with the mixed mode fracture analysis of a weakened orthotropic half-plane with multiple cracks propagation. The orthotropic half-plane contains Volterra type glide and climb edge dislocations. It is assumed that the medium is under in-plane loading conditions. The distributed dislocation technique is used to obtain integral equations for the dynamic problem of multiple ...

Sternoclavicular dislocations account for less than 5% of all dislocations of the scapular belt. Most cases of anterior dislocation of the sternoclavicular joint do not present symptoms. However, some patients may develop chronic anterior instability and remain symptomatic, and surgical treatment is indicated in these cases. There is a scarcity of reports in the literature relating to reconstru...