Contrast X-rays

It is shown how phase contrast X-ray microtomography can be realised with a (commercial) polychromatic X-ray microfocus tomograph provided the source size and the resolution of the detector are sufficiently small and the distance between source and detector is sufficiently large. The technique opens perspectives for high resolution tomography of light objects... 

Rubidium-82 myocardial perfusion images are used to study patients with myocardial ischemia or infarction. An example of this study is shown in Figure 8. Three patients with known myocardial infarction were imaged with Rb-82. Twenty millicuries of Rb-82 were administered in a 20 ml bolus in 20 sec. Data accumulated from 0-90 seconds post infusion show the blood pool as the radioactivity enters the right side of the heart, flows out to the lungs, and returns to the left side of the heart. Data accumulated from 90-300 seconds reflect uptake of Rb-82 in the myocardium as distributed by blood flow. These results by a non-invasive procedure correlated with the results of catheterized contrast x-ray studies (27,28). 

X-Ray diffraction studies of aqueous CdS04 solutions have clearly demonstrated the formation of O-sulfato complexes.668-670 These are of the general form [Cd(H20)6- (0S03) ](2-2")+, and appear to be the major species present in concentrated solutions. These results are fully in accord with tensimetric studies of the cadmium and magnesium sulfate aqueous systems, which indicate an increased interionic attraction at elevated temperatures.671 In contrast, X-ray diffraction studies on cadmium perchlorate solutions show no evidence for the coordination of the perchlorate ion to the metal, the only cationic species present being [Cd(H20)6]2+(Cd—O, 2.292 A, cf. Cd—O, 2.292 A in solid [Cd(H20)6][C104]2),670... 

Falcone, P.M., Baiano, A., Zanini, F., Mancini, L., Tromba, G., Montanari, F., and Del Nobile, M. A. 2004a. A novel approach to the study of bread porous structure Phase-contrast X-ray microtomography. J. Food Sci. 69(1), 38-43. 

Finally, it should be noted that vibrational (both IR and Raman) spectroscopy is unique in that it is applicable to the solid state as well as to the gaseous state and solution. In contrast, X-ray diffraction is applicable only to the crystalline state, whereas NMR spectroscopy is applicable largely to the sample in solution. 

Barium, like all elements with large atomic number, absorbs X-rays strongly, and a thin paste of barium sulfate and water is swallowed as a barium meal to obtain contrasting X-ray photographs and fluoroscopic views of the alimentary tract. The solubility of the substance is so small that the poisonous action of most barium compounds is avoided. 

X-ray examination An antegrade contrast-medium enema into the small intestine might be indicated in the case of suspected bleeding in this area. A contrast X-ray of the colon using barium is only indicated in isolated cases. 

A model of structure has been developped from electron microscopy and X-ray studies in Nafions (6). No basic difference exists between X-ray and neutron techniques. Nuclear interactions of neutrons with matter are characterized by the coherent scattering length and the corresponding values for H and D are very different Because of the different origins of the contrast, X-ray and neutron small angle scattering techniques are complementary. 

At room temperature, the vibrational spectroscopy data are still contradictory about a number and nature of the transformations above 20 GPa. A sequence of new phases has been reported on the basis of several splitting of the Raman vibron modes [24], including one just above 20 GPa [27]. In contrast, x-ray studies indicate the stability of 8 phase to 50 GPa [26, 33] in agreement with latter Raman study [34]. A change in x-ray diffraction pattern was observed above 60 GPa [36], but interpretation requires additional measurements. Recent Raman and IR measurements to 42 GPa show clear correspondence between the number of observed lattice and vibron modes and group-theoretical predictions for the 8 phase [9]. 

O Reading Check Compare and contrast X rays and gamma rays. 

The study shows that only two of these are detectable in a jet expansion (I and II), and both of them correspond to an extended rather than a folded carbon backbone chain. In contrast. X-ray diffraction structures of the same molecule in the condensed phase predict a folded chain. 

Friis, E. M., Crane, P. R., Pedersen, K. R. et al. (2007). Phase contrast X-ray microtomography links Cretaceous seeds with Gnetales and Bennettitales. Nature, 450,549-552. 

Eastwood DS, Bradley RS, Tariq F et al (2014) The application of phase contrast X-ray techniques for imaging Li-ion battery electrodes. Nucl Instrum Methods Phys Res Sect B Beam Interact with Mater Atoms 324 118-123. doi 10.1016/j.nimb.2013.08.066... 

The indirect methods for fiber-matrix adhesion-level measurement are shown in Fig. 2. These include the variable curvature method the slice compression test, the ball compression test, the fiber-bundle pull-out test the use of dynamical-mechanical thermal analysis and voltage-contrast X-ray photoelectron spectroscopy (VCXPS). 

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