Classical X-rays Research Articles

Gradient of Residual Stress and Lattice Parameter in Mechanically Polished Tungsten Measured Using Classical X-rays and Synchrotron Radiation

In this work, the stress gradient in mechanically polished tungsten sample was studied using X-ray diffraction methods. To determine in-depth stress evolution in the very shallow subsurface region (up to 10 μm), special methods based on reflection geometry were applied. The subsurface stresses (depth up to 1 μm) were measured using the multiple-reflection grazing incidence X-ray diffraction method with classical characteristic X-rays, while the deeper volumes (depth up to 10 μm) were investigated using energy-dispersive diffraction with white high energy synchrotron beam. Both complementary methods allowed for determining in-depth stress profile and the evolution of stress-free lattice parameter. It was confirmed that the crystals of tungsten are elastically isotropic, which simplifies the stress analysis and makes tungsten a suitable material for testing stress measurement methods. Furthermore, it was found that an important compressive stress of about − 1000 MPa was generated on the surface of the mechanically polished sample, and this stress decreases to zero value at the depth of about 9 μm. On the other hand, the strain-free lattice parameter does not change significantly in the examined subsurface region.

Concordancia diagnóstica del ultrasonido versus Rayos X, para fracturas de huesos pequeños, Servicio de Emergencia del Hospital de los Valles, Cumbayá, 2015-2017

Los traumatismos de extremidades son una de las principales causas de morbilidad en nuestro medio. El ultrasonido ha surgido como un elemento de diagnóstico de bajo costo, rápido y sin efectos que deterioren la salud. La exploración del componente músculo esquelético con ultrasonido de las extremidades se puede hacer con facilidad pero requiere de entrenamiento para la interpretación adecuada de las imágenes. Los estudios convencionales como la radiografía y tomografía son útiles, sin embargo, son de mayor costo y con riesgos para la salud. Los equipos de ultrasonido son de fácil instalación y han demostrado tener utilidad en el diagnóstico de fracturas de huesos largos especialmente. Objetivo: comparar la efectividad del ultrasonido versus rayos X en traumatismos cerrados agudos en extremidades superiores e inferiores en pacientes con sospecha de fracturas de huesos pequeños. Materiales y Métodos: Este fue un estudio de corte-transversal que incluyó a cuarenta y tres pacientes consecutivos ingresados ​​en el departamento de emergencias con sospecha de fracturas de huesos pequeños de extremidades debido a un trauma. Fueron evaluados por ultrasonido y rayos X para establecer su concordancia. El diagnóstico final de la presencia o no de una fractura fue establecido por el criterio clínico de un traumatólogo.Resultados: Con el método ecográfico fue posible diagnosticar un 26% más de fracturas que con los rayos x. Hubo una moderada concordancia 73.68% y un índice kappa 0,51 p<0.0002.Conclusiones: La concordancia establecida es moderada, probablemente a expensas de la mayor capacidad de diagnóstico del ultrasonido.

Analysis of stresses and crystal structure in the surface layer of hexagonal polycrystalline materials: a new methodology based on grazing incidence diffraction

The multireflection grazing-incidence X-ray diffraction (MGIXD) method is commonly used to determine a stress gradient in thin surface layers (about 1–20 µm for metals). In this article, the development of MGIXD to enable the determination not only of stresses but also of thec/aratio and thea0strain-free lattice parameter in hexagonal polycrystalline materials is presented and tested. The new procedure was applied for the results of measurements performed using a laboratory X-ray diffractometer and synchrotron radiation. The evolution of stresses and lattice parameters with depth was determined for Ti and Ti-alloy samples subjected to different mechanical surface treatments. A very good agreement of the results obtained using three different wavelengths of synchrotron radiation as well as classical X-rays (CuKα radiation) was found.

SP0126 Fractures in spondylathropathy: Prevention and management

Spondylarthropathies (SpA) are associated with an increased risk of clinical and radiographic vertebral fractures (VF). This has most extensively been documented in ankylosing spondylitis (AS). Two types of VF have...

Axis or Harris Ring in odontoid fractures, old fashioned but not obsolete

Clearing the cervical spine after blunt trauma remains a challenge. Even in the computed tomography era many emergency departments worldwide still use classical X-rays in first evaluation. Low odontoid fractures are frequently missed, especially in unconscious patients where an open mouth view is not available. Evaluation of the Harris ring in the lateral view can improve identification rate. We studied the diagnostic values of this sign and the educational effect on trainees. Lateral views of 12 computed tomography confirmed low-axis fractures and 13 controls were randomly presented to 17 residents (traumatology, neurosurgery and emergency medicine) and five experienced radiologists. After the residents were taught the use of the axis ring, they had to review the set. Diagnosis was scored with a degree of certitude from 5 to 1. The specificity and sensitivity for the radiologists was 88% (confidence interval 80-96) and 82% (confidence interval 72-91), respectively. The effect of the education on the scores of the residents was evaluated using the Wilcoxon ranking test with a significant effect for the traumatologists (P=0.0008), emergency physicians (P=0.0005) as well for the neurosurgeons (P=0.0087). The axis ring can be a useful diagnostic tool in identifying low odontoid fractures on cross-table cervical spine X-rays. It is easy to teach and should be included in X-ray-based C-spine clearing protocols.

Einsatz bildgebender Verfahren bei der Diagnostik der Osteoporose Interpretation der Röntgenbilder und Messprotokolle der Knochendichte

According to the recently published BoneEVA study, 7.8 million Germans (6.5 million women) are affected by osteoporosis. Of them, 4.3% experienced at least one clinical fracture. Only 21.7% were treated with an anti-osteoporotic drug, whereby only 10% received a bisphosphonate and 17% given calcium and vitamin D. On the other hand, as osteoporosis may be associated with severe pain in 90% of patients, analgesics are prescribed. The total direct costs attributable to osteoporosis amounted to Euro 5.4 billion in 2003. One out of three postmenopausal women and one out of five men over the age of 50 years will experience osteoporotic fractures unless preventive measures are undertaken. According to the German guidelines for diagnosis and treatment of osteoporosis, bone densitometry using dual energy x-ray absorptiometry (DXA) together with other clinical risk factors (previous low trauma fracture, use of nicotine, low body weight [BMI<20 kg/m2], immobilisation, and more than two falls during the last six months) are recommended for diagnosis. Using typical cases out of clinical practice, this article delineates frequent mistakes in the interpretation of DXA measurements. Furthermore, the present paper clarifies the role of classical x-rays, which still represent the predominant procedure for the identification of fractures and especially vertebral fractures. In comparison to x-rays, CT or MRI are more important in differential diagnosis of malignant disease and bone metastases. Essentially a reduction of vertebral height without evidence of central endplate fracture in postmenopausal women may be unrelated to osteoporosis. Quantitative morphometry should not be used alone for the assessment of vertebral fracture in clinical decision-making. Therefore, we recommend differential diagnosis of morphometric vertebral deformities by an expert reader to rule out deformities related to degenerative disease and norm variants of which we will present several examples to train the view of the reader.

Secondary ionization mass spectrometry imaging of dilute stable strontium labeling in dentin and enamel

The labeling of the zones of active mineralization in bone and tooth is usually achieved with calcium-binding fluorescent dyes. However, these compounds are labile and mostly lost during the maturation process of the growing tissue. Here we labeled mouse teeth using injections of dilute strontium (SrCl 2, 500 μg/ml), a trace element that is naturally incorporated in hydroxyapatite, and resolve the subtle induced compositional changes using secondary ion mass spectrometry (SIMS) imaging and analysis. Entire hemi-mandibules sampled at 14 and 28 days after birth are embedded in resin and polished along longitudinal sections. SIMS chemical imaging reveals the double Sr labeling both in dentin and enamel of molar teeth as two stripes with excess Sr concentration parallel to the dentino-enamel junction. In order to quantify the variations of the strontium/calcium ratio (Sr/Ca), two international standards were sintered and measured along with the samples. The concentration of Sr in the two stripes is about 300 μg/g, which corresponds to an enrichment factor of about 1.3–1.4 relative to the natural baseline. These results show that SIMS provides rapid and quantitative imaging of small abundances of stable isotopes in growing mineralized tissues with a sensibility that is at least two orders of magnitude higher than classical X-rays microanalysis.

Evaluation by Synchrotron Radiation of Shape Factor Effects on Residual Stress in Nitrided Layers

Nitriding is a thermo-chemical treatment to improve fatigue life of steel parts what are exposed to high cyclic loading on and close to the surface like gears for example. During the nitrogen diffusion, the precipitation of nitrides and carbides generates residual stresses and increases the superficial hardness. These residual stresses are function of the conditions of the nitriding process but also critically depend on the geometry of the steel components. Indeed, the result of the diffusion process is different for a plane geometry or a curvilinear one. In this present work, the sample is a part of a gear, composed by two teeth. Between two teeth of gear, the determination of in-depth stress gradients by classical X-rays diffraction cannot be done with a great accuracy: the spatial resolution is not sufficient because the irradiated area has the same dimension than the surface curvature of the component. Furthermore, it is very difficult to take into account the removal of matter that is required to determine in-depth stress profile because of the particular geometry. The synchrotron diffraction technique is a well-adapted method to determine such stress gradients in strongly absorbing materials due to the capability of penetration power of high energy X-rays. The removal of matter is not required and it is possible to determine an in-depth map of the stress tensor. After measurements on the ESRF ID15 beam line, stress profile has been calculated without the σ33 equal to zero hypothesis. The results are as following: compressive residual stresses were found close to the surface, and the calculated σ33 component of stress tensor is really not equal to zero. This important result seems to show the geometrical effect on stress state near non-plane surface.

Recent Experimental and Theoretical Studies of Molecular and Layered Metal-Radical Based Magnets

Abstract We report in this paper the preparation and magnetic properties of layered metal(II) hydroxynitrates and hydroxyacetates which display, according to the metal ion, either ferro (Co(II) and Ni(II)) or antiferromagnetic (Cu(II)) intralayer interactions. These compounds are shown to be suitable host lattices for organic species. 2,6- and 2,5- pyridine-based nitronyl-nitroxide biradicals have been synthesized and their magnetic properties investigated. They respectively display ferro- and antiferromagnetic behaviors. X-rays studies show an angle of 88° (in the 2,6 case) and 0° (in the 2,5 case) between both radicals. The synthesis of a new imino-nitroxide benzoic acid radical, characterized by classical methods and X-rays diffraction, and preliminary results of exchange reaction with copper(II) basic salts are also discussed.

Structural studies of amorphous CoP and NiP by EXAFS

The EXAFS spectra of amorphous CoP and NiP alloys have been recorded and analyzed on both edges of the metal and metalloid. The spectra cannot be directly fitted by the classical neutrons or X-rays results: these appear to be the average values of asymmetric radial distribution functions that we have to use in EXAFS analysis. Then we show that the environment of the phosphorus atoms in the amorphous state is very reminiscent of that of the Co2P or Ni3P crystalline materials.

Etude radiologique des centres de rotation du poignet

To ensure the total replacement of wrist, it seems necessary to determine the main kinematic specifications of mobility and stability of this joint. After a review of the literature, the authors have determined, by the classical X-rays graphic method, the positions of both radial-ulnar deviation and flexion-extension centers, on 26 alive normal wrists. The data, in some ways different from Youm's, introduce to the conditions of stability of any wrist in a functional situation. The center locus (on the forearm axis in a front view, quite anterior in a lateral view) is, in some ways, an answer to the question of muscular equilibrium during prehensile efforts, so to the amount of strains the joint must bear, and consequently to the design of a total wrist prosthesis.