Dislocations Research Papers - Academia.edu (original) (raw)

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- Risk assessment, Orthopaedics, Humans, Female
- by Håkan Ahlström
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- Magnetic Resonance Imaging, Evaluation, Humans, Image Reconstruction

The effect of corrosive solutions on stress relaxation behavior of pure Mg and its alloys is studied. Pure magnesium shows a crucial corrosion stress relaxation in 3.5wt.% NaCl even at room temperature in comparison with tests in air. Die-cast Mg alloys AZ91D, AM50 and AS21 at room temperature show a relatively small stress decrease both in air and in different

- by Emmanuel Gutman
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- Stress relaxation, Magnesium, Dislocations, Grain Boundary

Snowflakes and silicate mushes are two examples of the terrestrial regimes that may be characterized as partially solidified systems. Change of phase in clouds and magma chambers as well as in the earth's mantle and core introduces a variety of phenomena to challenge both the mathematical modeler and the experimentalist intent upon understanding the nature of such processes. Paralleling the efforts of researchers in the natural sciences, metallurgists and materials scientists have extensively investigated solidification in alloy melts to discover the controlling mechanisms for undesirable behavior such as melt segregation, freckling (Figure 1), and crystal dislocation. Unfortunately, most of the studies, whether in the geosciences or in material sciences, have focused on highly specialized problems with little or no attempt at generalizing the results or methods to other physical systems. During May 12-16, 1986, at the Stanford University Conference Center at Fallen Leaf Lake, ...

- by Charles Carrigan
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- Mineralogy, Materials Science, Petrology, Crystal Growth
- by Claudio Furtado
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- Materials Engineering, Condensed Matter Physics, Nanotechnology, Magnetic field
- by Bruno Chrcanovic
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- Computed Tomography, Oral and Maxillofacial Surgery, Humans, Emergency Room
- by Peter Lagerlof
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- Materials Engineering, Mechanical Engineering, Microstructure, Grain Boundaries
- by Kenneth Bond
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- Resource use, Prospective studies, Humans, Female
- by Matthias Holschneider
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- Geophysics, Kinetics, Dislocations, Scale Space

An asymptomatic enlargement of the medial clavicle is a condition that is often both missed and misdiagnosed. We review the most common causes of an isolated and asymptomatic enlargement of the medial clavicle. Underlying aetiologies include osteoarthritis of the sternoclavicular joint, condensing osteitis, spontaneous dislocation of the sternoclavicular joint, and sternocostoclavicular hyperostosis. Key points in the history and physical examination as well as characteristic radiographic findings are sufficient for correct diagnoses. Treatment is conservative.

- by Sandy Milgraum
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- Osteoarthritis, Humans, Clavicle, Dislocations
- by Farida Selim
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- Dislocations, Spectrum, Residual Stress, Positron Annihilation Spectroscopy

SUMMARY : Dislocation of the radial head with ipsila- teral fracture of the shaft of the radius : a case report. Ipsilateral radial head dislocation with radial shaft fracture is a rare injury. A few cases have been reported in the literature. We report the case of a 39-year-old man who pre- sented with a radial shaft fracture and ipsilateral

- by R. Ben Ghozlen and +1
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- Case Report, Dislocations

The electron and hole mobility of Si complementary metal on oxide field effect transistors (CMOS) can be enhanced by introducing a biaxial tensile stress in the Si channel. This paper outlines several key analytical techniques needed to investigate such layers. Raman scattering is used to measure the strain in the Si channel as well as to map the spatial distribution of strain in Si at a lateral resolution better than 0.5 μm. Atomic force microscopy (AFM) is used to measure the surface roughness. Transmission electron microscopy (TEM) is used to reveal dislocations in the structure, the nature of the dislocations and the propagation of the dislocations. Secondary ion mass spectrometry (SIMS) is used to monitor the Ge content profile in the structure and the thickness of each layer. In the long term, inline nondestructive techniques are desired for epi-monitoring in manufacturing. Two techniques, spectroscopic ellipsometry (SE) and x-ray reflectivity (XRR), have shown promise at this stage.

- by Vikram Kumar
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- Far Infrared Physics, Leakage Current, Dislocations, Temperature Dependence

Single crystal X-ray diffraction was applied in order to investigate defect-induced microstructures in radiation damaged zircon. The formation of domains with different degrees of order was observed and in particular, it was possible to distinguish two types of defects: isolated lattice defects and dislocations. These lattice deformations have a great influence on the structural and physical properties of the materials.

- by Isabella Memmi
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- Engineering, Materials Science, RADIATION DAMAGE, Dislocations

High-energy trauma may result in uncommon open injuries around the elbow joint. The management of these injuries can be difficult. Fourteen patients were treated between 1999 and 2003 and their injuries consisted of Monteggia fracture-dislocations combined with segmental fractures of the ulna or fractures of the forearm bones and/or various more complex trauma such as neural injuries, bone comminution and severe soft tissue injuries around the elbow. Eight of them (57%) were multiply injured with severe additional injuries. All patients underwent surgery within first 4-6 hours. Internal fixation, external fixation or a combination of both methods were used to stabilize fractures while open wounds had secondary closure. Additional operations were required in 6 patients. The functional results according to the Mayo Elbow Performance Index were excellent or good in eleven patients, and fair or poor in the remaining three. The patients with fair and poor results had suffered from severe...

- by Elhadi Sariali
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- Biomedical Engineering, Prospective studies, Humans, Female
- by Kaj Knutson
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- Biomedical Engineering, Comparative Study, Osteoarthritis, Sweden
- by B. Venkateswaran
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- Dislocations, Clinical Sciences
- by Sofia Cerda-Gonzalez
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- Veterinary, Dogs, Female, Animals
- by Russell Travis
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- Nursing, Pain, Chronic Pain, Occupational Medicine

ABSTRACT The SmartCut process was first developed to obtain silicon-on-insulator (SOI) materials. Now an industrial process, the main Unibond SOI-structure trends are reported in this paper. Many material combinations can be achieved by this process, because it appears to enable the generic development of new structures. Several of the new structures combining different materials and different bonding layers are described. These include SiGe and strained-Si films onto an oxidized Si wafer, silicon-on-insulating multilayer (SOIM) structures, and InP or 4H-SiC film transfers onto low-cost substrates via metallic or even refractory conductive-film bonding layers. More recently, an original bonding process based on mark patterning, wafer bonding, and layer transfer has been proposed to obtain structures in which the relative crystalline-axis orientations of both the film and the substrate can be controlled accurately. In this case, a SmartCut process that includes a mark-patterning step appears well suited for precise control of axis orientations. A procedure is described to obtain an ultra-thin Si film bonded onto a Si wafer. An example of a pure screw-dislocation network achieved by the mark patterning, bonding, and layer-transfer process is reported in this paper. The results have important implications for nanostructure development.

- by B. Osternaud and +2
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- Electronic Materials, Thin Film, Dislocations, Silicon on Insulator
- by James Leone
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- Probability, Humans, Female, Male

The present work adresses the evaluation of modified 9Cr-1Mo steels magneic hystersis loop and magnetic Barkhsuen emission techniques for the samples subjected to high temperature ageing for different durations. The initially quenched and then tempered material revealed different magnetic behaiour with ageing. The relxation of stresses and reduction of high value of dislocations due to quenching in the initial perriod of ageing was observed with lowering of coercivity and an increase in MBE signal. Further ageing above 150 hours led to fine distribution of carbides in the matrix which led to the subsequent magnetic hardening. The formaiton of the fine carbides was also observed from Scanning electron micrographs. At higher ageing periods beyond 500 hours, the carbides migrated towards the grain boundary leading to loweing in the density of the fine carbides in the matrix and a consequent magnetic softening due to easy domain wall propagation.

- by JN Mohapatra
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- Materials Science, Dislocations, Domain wall, High Temperature
- by Ikumu Watanabe
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- Materials Engineering, Mechanical Engineering, Civil Engineering, Plasticity

Nanostructuring metals through nanograins and nanotwins is an efficient strategy for strength increase as the mean free path of dislocations is reduced. Yet, nanostructures are thermally often not stable, so that the material properties deteriorate upon processing or during service. Here, we introduce a new strategy to stabilize nanotwins by an interfacial nanophase design and realize it in an interstitial high-entropy alloy (iHEA). We show that nanotwins in a carbon-containing FeMnCoCrNi iHEA can remain stable up to 900 °C. This is enabled by co-segregation of Cr and C to nanoscale 9R structures adjacent to incoherent nanotwin boundaries, transforming the 9R structures into elongated nano-carbides in equilibrium with the nanotwin boundaries. This nanoscale 9R structures assisted nano-carbide formation leads to an unprecedented thermal stability of nanotwins, enabling excellent combination of yield strength (~1.1 GPa) and ductility (~21%) after exposure to high temperature. Stimulating the formation of nano-sized 9R phases by deformation together with interstitial doping establishes a novel interfacial-nanophase design strategy. The resulting formation of nano-carbides at twin boundaries enables the development of strong, ductile and thermally stable bulk nanotwinned materials.

- by Neil Cunningham
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- Adolescent, Humans, Female, Male

The plane elasticity problem studied is of a circular inclusion having a circular arc-crack along the interface and a crack of arbitrary shape in an infinite matrix of different material subjected to uniform stresses at infinity. The solution of the problem is given using Muskhelishvili's complex variable method with sectionally holomorphic functions. First, the solution to the (auxiliary) problem of a dislocation (or force) applied at a point in the matrix with the circular inclusion partially bonded is derived fully in its general form by solving the appropriate Rieman-Hilbert problem. It is subsequently used as the Green's function for the initial problem by introducing an unknown density function associated with a distribution of dislocations along the crack in the matrix. The initial problem is then reduced to a singular integral equation (SIE) over the crack in the matrix only. The SIE is solved numerically by appropriate quadratures and the stress intensity factors ...

- by Stavros Ristanis and +1
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- Dislocations, Clinical Sciences, Conservative treatment
- by BY Xia
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- Materials Engineering, Condensed Matter Physics, Phase Transitions, Dislocations

Background The arterial vascularity of the hip has been investigated in normal infants using duplex Doppler sonography. This study addressed the differences in hip vascularity in infants with respect to gender and acetabular morphology. Objective To determine whether there is a relationship between the resistive index of the vessels of the femoral chondroepiphysis and the alpha angle in normal infant hips and in those with developmental dysplasia of the hip. Materials and methods We studied 76 hips (38 patients) with gray-scale and power Doppler US. The patients were referred because of a possible abnormal clinical hip examination or had risk factors for developmental dysplasia of the hip. The infants ranged in age from 1 day to 6 weeks. There were 13 boys and 25 girls. Gray-scale images were initially performed in the coronal and transverse planes to evaluate acetabular morphology, alpha angle and position of the femoral chondroepiphysis relative to the acetabulum. The hips were then examined with power Doppler US, in both sagittal and transverse planes, to identify arterial vessels within the femoral epiphysis. Resistive indices were then recorded from the spectral analysis in each vessel identified. Each examination was performed by one of five pediatric radiologists. Mixed model regression was used to assess the relationship between resistive index and alpha angle, age and gender. Results Of the 76 hips, 34 had an alpha angle of 60° or greater and were classified as normal, 26 had an alpha angle between 50° and 59° and were classified as immature, and 13 had an alpha angle of less than 50° and were either subluxed or dislocated at the time of examination. At least two vessels were documented in each femoral epiphysis except in three hips, in which no vessels could be documented because of technical factors. There was a statistically significant linear relationship between the alpha angle and resistive index, such that the resistive index tended to rise with increasing alpha angle (P=0.0022). In addition, female infants had a significantly higher average resistive index than the average resistive index in male infants with the same alpha angle (P=0.0005). Conclusion There is a direct linear relationship between alpha angle and resistive index in the infant hip. Female infants have a higher average resistive index than male infants. We believe that these results might serve as a model for predicting an infant hip at risk of ischemia. In addition, the fact that lower resistive indices of the femoral epiphysis are associated with acetabular dysplasia might help explain the documented low incidence of avascular necrosis in untreated hip dysplasia.

- by John Amodio
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- Humans, Femur, Spectral analysis, Female
- by W. Wierzchowski
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- Engineering, X Rays, Physical sciences, Dislocations
- by Pascal Christel
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- Magnetic Resonance Imaging, Wound Healing, Adolescent, Humans
- by Naohiro Shibuya
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- Humans, United States, Female, Male
- by Gabriela Porto and +1
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- Dentistry, Temporomandibular Joint, Titanium, Literature Review
- by Nico Dantuma
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- Molecular Biology, Protein Folding, Biological Sciences, Molecular
- by Gabriel Abba and +1
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- Metal Forming, Finite element method, Finite Element Analysis, Dislocations
- by Erik Van der Giessen
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- Materials Engineering, Dislocations, Single Crystal, Three Dimensional
- by Laura W Bancroft, MD, FACR
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- Radiology, Computed Tomography, Peer Review, Humans

The objective of this review article is to provide a concise discussion of atomistic modeling efforts aimed at understanding the nanoscale behavior and the role of grain boundaries in plasticity of metallic polycrystalline materials. Atomistic simulations of grain boundary behavior during plastic deformation have focused mainly on three distinct configurations: (i) bicrystal models, (ii) columnar nanocrystalline models, and (iii) 3D nanocrystalline models. Bicrystal models facilitate the isolation of specific mechanisms that occur at the grain boundary during plastic deformation, whereas columnar and 3D nanocrystalline models allow for an evaluation of triple junctions and complex stress states characteristic of polycrystalline microstructures. Ultimately, both sets of calculations have merits and are necessary to determine the role of grain boundary structure on material properties. Future directions in grain boundary modeling are discussed, including studies focused on the role of...

- by David McDowell
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- Materials Engineering, Mechanical Engineering, Materials Science, Microstructure
- by Stephen Woodbury
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- Economics, Latin American Economic History, Unemployment Duration, Job Search
- by Stefan Rammelt
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- Nursing, Adolescent, Humans, Child
- by Edward Kenik
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- Crystal structure, Dislocations, Microstructures, Ion Beam
- by Branislav Jaramaz
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- Dislocations, Total Hip Replacement, Simulation Software
- by Brendan Lilley
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- Biochemistry, Bioinformatics, Developmental Biology, Climate Change

A simple extension of the thermodynamic dislocation theory to non-uniform plastic deformations is proposed for an analysis of high-temperature torsion of aluminum bars. Employing a small set of physics-based parameters, which we expect to be approximately independent of strain rate and temperature, we are able to fit experimental torque-twist curves for five different twist rates and at one fixed ambient temperature. We find that thermal softening due to temperature rise is significant at high twist rates.

- by Khanh Chau Le and +1
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- Thermodynamics, Continuum Mechanics, Dislocations
- by James Savage
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- Multidisciplinary, Dislocation, Dislocations, Rigidity
- by NIKHIL SHARMA
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- Crystal Growth, Transmission Electron Microscopy, Dislocations, High Resolution

We present models of localized plastic deformation inside Persistent Slip Band channels. First, we investigate the interaction between screw dislocations as they pass one another inside channel walls in copper. The model shows the mechanisms of dislocation bowing, dipole formation and binding, and nally dipole destruction as screw dislocations pass one another. The mechanism of (dipole passing) is assessed and

- by Nasr Ghoniem
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- Copper, Dislocations, Plastic deformation, Dislocation dynamics