Disorder-sensitive superconductivity in the iron silicide Lu2_2Fe3_3Si5_5 studied by the Lu-site substitutions

We studied effect of non-magnetic and magnetic impurities on superconductivity in Lu$_2$Fe$_3$Si$_5$ by small amount substitution of the Lu site, which investigated structural, magnetic, and electrical properties of non-magnetic (Lu$_{1-x}$Sc$_x$)$_2$Fe$_3$Si$_5$, (Lu$_{1-x}$Y$_x$)$_2$Fe$_3$Si$_5$, and magnetic (Lu$_{1-x}$Dy$_x$)$_2$Fe$_3$Si$_5$. The rapid depression of $T_c$ by non-magnetic impurities in accordance with the increase of residual resistivity reveals the strong pair breaking dominated by disorder. We provide compelling evidence for the sign reversal of the superconducting order parameter in Lu$_2$Fe$_3$Si$_5$.Comment: 4 pages, 5 figure

Prediction of inorganic superconductors with quasi-one-dimensional crystal structure

Models of superconductors having a quasi-one-dimensional crystal structure based on the convoluted into a tube Ginzburg sandwich, which comprises a layered dielectric-metal-dielectric structure, have been suggested. The critical crystal chemistry parameters of the Ginzburg sandwich determining the possibility of the emergence of superconductivity and the Tc value in layered high-Tc cuprates, which could have the same functions in quasi-one-dimensional fragments (sandwich-type tubes), have been examined. The crystal structures of known low-temperature superconductors, in which one can mark out similar quasi-one- dimensional fragments, have been analyzed. Five compounds with quasi-one-dimensional structures, which can be considered as potential parents of new superconductor families, possibly with high transition temperatures, have been suggested. The methods of doping and modification of these compounds are provided.Comment: 22 pages, 14 figures and 2 table

Effects of vitamin E on the distribution and metabolism of nitrofurantoin in rats

Previous studies have shown a significant increase in the pulmonary toxicity of nitrofurantoin (NF) in animals fed a diet lacking vitamin E. The authors have therefore examined the pharmacokinetics of NF in control and vitamin E-deficient male Sprague-Dawley rats. NF was rapidly absorbed following subcutaneous injection and was cleared from all tissues examined (blood, lung, liver and kidney) in a biphasic manner. Substantial metabolism of the drug was observed, and the disposition of NF metabolites was qualitatively similar to that of the parent compound. The most apparent difference between control and vitamin E-deficient animals was a significant increase in tissue metabolite levels 4-16 hr after treatment. Unchanged NF was also elevated in all tissues examined 16 hr after treatment in the vitamin E-deficient animals. Urinary excretion of NF and metabolites accounted for 68% of the total dose in control rats and 35% in vitamin E-deficient rats. This study illustrates a marked alteration in NF disposition in animals fed a diet lacking vitamin E when compared with controls. The observed alterations appear to be related to a decreased renal clearance of both NF and metabolites