ABSTRACT
X-ray absorption fine structure at the sulfur K edge in Mg(1-x)Fe(x)S solid solution (0 < or = x < or = 0.68) has been measured at the Canadian Synchrotron Radiation Facility. It was shown that the S K-edge in MgS was formed by the multiple scattering of the photoelectron wave within a cluster of large size (containing 27 atoms and having radius about 4.5 A). Comparison of experimental data with theoretical results allows study of the electronic structure of this system. The analysis of partial electronic density of s-, p- and d- states makes it possible to investigate the mutual influence of sulfur s-, p- and metal d- states in the conduction band. The study of changes in experimental S K-edges XANES of Mg(1-x)Fe(x)S solid solution with variation of relative Fe-Mg concentration allows the extraction of the hypothetical cubic phase (B1) of FeS, and this is supported by theoretical simulation.
ABSTRACT
In a crossover, double-blind comparison, circulatory changes induced by hemodialysis with bicarbonate versus acetate dialysate were evaluated at the first exposure as well as after 2 weeks of acclimatization to each dialysate. Hemodialysis with bicarbonate dialysate resulted in only minor changes in blood pressure and left ventricular (LV) function as assessed by M-mode echocardiography. In contrast, the first exposure to acetate resulted in significant decreases in systolic (30 mm Hg) and diastolic (17 mm Hg) blood pressure as well as in LV end-diastolic and end-systolic dimensions (5-6 mm) and a rise in ejection fraction. After acclimatization, tolerance developed for the arterial vasodilatory effects of acetate, but not for the venous vasodilatory effect (persistent decrease in LV end-diastolic dimension). These results indicate that some of the circulatory changes induced by hemodialysis may be related more to the acetate infused than to fluid losses or relative autonomic insufficiency.
