The nature and configuration of the dislocations generated during the incipient stages of plasticity in nanoindentations are still to a large extent unclear. In previous studies we have recognised and characterised by STM a number of novel surface defects in the surface of fcc metals generated by nanoindentation. We have analysed [1] the generation and kinetics of two types of dislocation confi...

The authors retrospectively evaluated the effects of a single cortical screw in the open reduction and internal fixation of displaced distal clavicle fractures. Fifteen patients without associated acromioclavicular joint dislocation were treated by open reduction and internal fixation with a single cortical screw (4.5-mm diameter, 60-mm length) between 2004 and 2011. Mean follow-up was 39.2 mon...

Although the favored glide planes in hexagonal close-packed Zr are prismatic, screw dislocations can escape their habit plane to glide in either pyramidal or basal planes. Using ab initio calculations within the nudged elastic band method, we show that, surprisingly, both events share the same thermally activated process with an unusual conservative motion of the prismatic stacking fault perpen...

Ab initio calculations in bcc iron show that a 111 screw dislocation induces a short-range dilatation field in addition to the Volterra elastic field. This core field is modeled in anisotropic elastic theory using force dipoles. The elastic modeling thus better reproduces the atom displacements observed in ab initio calculations. Including this core field in the computation of the elastic energ...

The strain-rate response of flow stress in a plastically deforming crystal is formulated through a stress-sensitive dislocation mobility model that can be evaluated by atomistic simulation. For the flow stress of a model crystal of bcc Fe containing a 1/2[111] screw dislocation, this approach describes naturally a non-Arrhenius upturn at high strain rate, an experimentally established transitio...

Using first-principles simulations for the probability density of finding a 3He atom in the vicinity of the screw dislocation in solid 4He, we determine the binding energy to the dislocation nucleus E(B)=0.8+/-0.1 K and the density of localized states at larger distances. The specific heat due to 3He features a peak similar to the one observed in recent experiments, and our model can also accou...

Molecular dynamics (MD) simulations are used to investigate the response of a/2<111> screw dislocation in iron submitted to pure shear strain. The dislocation glides and remains in a (110) plane; the motion occurs exclusively through the nucleation and propagation of double kinks. The critical stress is calculated as a function of the temperature. A new method is developed and used to determine...

The behavior of jogged screw dislocations in y-TiAl alloys has been investigated with large-scale molecular dynamics (MD) simuIations. We find a new mechanism for formation of pinning points in jogged screw dislocations. We also find that the critical height for the jogs in the +[i10] directions on the (001) plane to move nonconservatively is between 3ro and 4r0, where ro is the nearest neighbo...

ABSTRACT Traumatic hip dislocations are common in high-energy motor vehicle accidents. We present a case of a 43-year old man who sustained posterior hip dislocation with posterior wall acetabular fracture and ipsilateral intertrochantric fracture following a motorcycle accident. Urgent open reduction and internal fixation of the hip fracture-dislocation and fixation of intertrochantric fractur...

We report the case of a 22-year-old woman who underwent plate and screw fixation for a traumatic left acetabular fracture and fixation with cancellous screws for an associated femoral neck fracture. Two months later, the internal fixation became infected and was removed. This resulted in a painful high dislocation of the hip. We solved the problem with continuous soft-tissue distraction using a...