STUDY DESIGN Four patients had C2-3 vertebral fusion and radiologically demonstrated cord compression at C3-4 level related to disc bulge with or without association of osteophytes and C1-2 posterior facetal dislocation. The outcome of treatment by atlantoaxial and subaxial facetal fixation is discussed. PURPOSE The article evaluates the significance of atlantoaxial facetal instability in cas...

We present a kinetic Monte Carlo method for simulating dislocation motion in alloys within the framework of the kink model. The model considers the glide of a dislocation in a static, three-dimensional solute atom atmosphere. It includes both a description of the short-range interaction between a dislocation core and the solute and long-range solute-dislocation interactions arising from the int...

Ball screw drives are widely used as the motion delivery mechanism due to their high stiffness and high accuracy. As the speed and precision requirements from machine tools increase, the effects of the structural flexibility of the drives on controller performance are becoming increasingly significant. The vibrations adversely affect the positioning accuracy and performance of the drive. The na...

OBJECTIVES The transoral atlantoaxial reduction plate system treats irreducible atlantoaxial dislocation from transoral atlantoaxial reduction plate-I to transoral atlantoaxial reduction plate-III. However, this system has demonstrated problems associated with screw loosening, atlantoaxial fixation and concealed or manifest neurovascular injuries. This study sought to design a set of individual...

Metals with nanoscale twins have shown ultrahigh strength and excellent ductility, attributed to the role of twin boundaries (TBs) as strong barriers for the motion of lattice dislocations. Though observed in both experiments and simulations, the barrier effect of TBs is rarely studied quantitatively. Here, with atomistic simulations and continuum based anisotropic bicrystal models, we find tha...

Unstable pelvic ring fractures raise treatment challenges in severely injured patients. Ilio-sacral screw fixation is an elegant option for stabilising the posterior lesion, which is a common source of residual pain. This technique provides secure fixation. The first description can be found in a 1913 treatise by Lambotte [1]. In 1978, Letournel reported the treatment of sacro-iliac joint dislo...

The as-grown surfaces of 6H SiC seed crystals grown by the Lely method have been characterized by visible light microscopy and atomic force microscopy. The surfaces were then used to seed the sublimation growth of SiC at 2300'C, in 650 torr of Ar, with a gradient of 8 °C/cm. Repeated observations of the seed surface structure after predetermined intervals in the growth reactor demonstrated that...

2014 Modern rapid-freezing methods followed by freeze-fracture replication techniques are ideally suited to allow the direct visualization of the three-dimensional structure and defects of thermotropic smectic and cholesteric liquid crystalline phases with resolution approaching molecular dimensions. Cholesterol nonanoate was quench frozen from near the smecticcholesteric transition to reveal e...

This study is to investigate the role of three-dimensional image navigation system for surgical treatment of odontoid fracture. A total of 21 patients were enrolled in this study. The anterior cervical hollow screw fixation was performed for treatment of acute odontoid fracture under monitoring of isocentric C-arm three-dimensional navigation system (Iso-C 3D) navigation system. The postoperati...

For a broad range of crystalline materials complex dislocation core structures have a significant effect on macroscopic plastic flow, causing unexpected deformation modes that are strongly influenced by other components of stress in addition to the glide stress on a given slip system and on the sign of stress. In this paper we use atomistic simulations of a screw dislocation in bcc molybdenum t...