Abstract The coordination of U 4+ and Th 4+ in concentrated CaCl 2 solutions is studied by U and Th L III edge extended X-ray absorption fine structure (EXAFS) spectroscopy. With the decrease of concentration of CaCl 2 from 6.9 to 4 M, the Cl − ion coordination number N Cl in the U 4+ coordination sphere decreases from 3.4 to 1.3, while the hydration number N O increases from 4.5 to 6.7. The combined coordination number N O +N Cl of U 4+ in concentrated Cl − solution (8.0), is lower than that in 1.5 M perchloric acid aqueous solution (9.0). For Th 4+ , the decrease of concentration from 6.9 to 4 M CaCl 2 , the coordination number N Cl in the Th 4+ coordination sphere decreased slightly from 1.9 to 1.5, while coordination number N O increased from 7.6 to 8.8. The N O +N Cl of Th 4+ in concentrated Cl − solution (9.0), is similar to that in 1.5 M perchloric acid. The bond distance of U–Cl (2.67 Å), is shorter than that of Th–Cl (2.76 Å), because of low coordination number N O to U 4+ . By adding HCl into the system, the U 4+ and Th 4+ coordination sphere is unchanged. The coordination structures of U 4+ and Th 4+ in concentrated LiCl is also discussed.
Introduction We have investigated the local structure of high temperature molten salts by using XAFS technique. We confirmed that it was difficult to analyze the high temperatuyre XAFS data(generally beyond 500 oC) by a standard curve fitting technique. We have used the cumulant expansion method[1] to treat an anharmonic vibration effect in the liquid. Our XAFS data was successfully analyzed by the expansion technique. However, it contains uncertain factor because of additional fitting parameters. Recently, Filipponi[2] reported from some XAFS data analysis examples that the curve fitting analysis procedure should not be used for high temperature liquid XAFS data. In the present work, we tried to obtain calculated XAFS function from a molecular dynamics(MD) technique and the FEFF8[3]. This new analysis procedure which does not use the curve fitting was evaluated by using the XAFS data of molten RbCl.
Crystal damage induced in hexagonal SiC by cutting was characterized by transmission electron microscopy and Raman scattering. Wiresawing with loose abrasive (WSLA) induces stacking faults (SFs), dispersive triangular crystal disordered areas, and dislocation half-loop bundles. Wiresawing with fixed abrasive (WSFA) induces SFs, crystal disordered layers, and dislocation half-loop bundles. Electric discharge machining (EDM) predominantly forms silicon, carbon, and 3C-SiC by 6H-SiC decomposition. The mechanisms inducing crystal damage by slicing were discussed on the basis of characterization results.
Manganese (Mn) accumulates at a higher level in the pancreas than in any other organs when excess Mn is administered to the rat. The present study is carried out to analyze the intracellular localization of Mn existed in the pancreatic cell of Mn-treated rats. Transmission electron microscope and X-ray micro-analysis connected with a rapid freezing fixation technique showed that a large amount of Mn was localized in lysosomal particles of the pancreatic cell of Mn-treated rats. The Mn-rich particles disappeared when the element-administration was discontinued, showing that the accumulation of Mn is reversible. To confirm that Mn is in the lysosomes, a centrifugal subcellular-fractionation and a neutron activation analysis were carried out. The result indicated that much Mn existed in the lysosomal fraction.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
