METAL-ION SUBSTITUTION CHEMISTRY IN THE YBACUO SYSTEM AS A PROBE OF THE SUPEREXCHANGE PATHWAY

The effect of subtitution for Cu by aluminum, nickel, and zinc in the YBaCuO superconducting system is described in detail. All three metals lower the Tc value and make the superconducting transition less abrupt. However, the strength of the effect varies with the metal, and this is attributed to their different reactivities and site preferences. The most dramatic effect is with zinc, which completely quenches the superconductivity when as few as 10% of the Cu sites are replaced. It is postulated that under these synthetic conditions zinc prefers the five-coordinated 'Cu(2)' site, which is presumed to lie on the main superconducting pathway. Nickel has a stronger affinity for the four-coordinated 'Cu(1)' sites and is apparently found in both sites at high dopant levels

Synthesis, Chemistry, Electronic Properties, and Magnetism in the Y-Ba-Cu-O Superconductor Systems

The relation of sample preparation conditions, including oxygen concentration, annealing and hot isostatic pressing, to the superconducting critical temperature of the title materials is described. New synthetic materials are examined and characterized by a variety of techniques, including magnetic susceptibility measurements, ESR, electron microscopy and X-ray diffraction. The relationship between magnetization and critical current is examined

Temporal changes in circulating P-selectin, plasminogen activator inhibitor-1, magnesium, and creatine kinase after percutaneous coronary intervention*

Objective: This study aims to determine the mechanisms underlying restenosis and ischemia-reperfusion injury of the myocardium after percutaneous coronary intervention (PCI). Methods: The present study examined serial changes (5 min, 30 min, 2 h, 6 h, and 24 h after PCI) in circulating P-selectin, plasminogen activator inhibitor-1 (PAI-1), magnesium (Mg), and creatine kinase-myocardial band fraction (CK-MB) levels, which may be associated with restenosis and myocardial injury in patients undergoing PCI. The occurrence rates of major adverse cardiovascular events were collected over a six-month follow-up. Results: PCI induced an early elevation of P-selectin, which correlated positively with the inflation pressure used in the PCI procedure. PCI also caused a significant and sustained decrease in serum Mg in PCI patients, without an effect on PAI-1. An increase in CK-MB was observed in PCI patients, although values were within normal reference range. In addition, elevated P-selectin and decreased Mg measured shortly after the coronary angioplasty procedure were associated with recurrent treatment and heart failure, respectively. Conclusions: Our study demonstrates that PCI induces temporal changes of P-selectin, Mg, and CK-MB, which may be involved in restenosis and ischemia-reperfusion injury. These findings highlight the need for using antiplatelet therapy and Mg to reduce the risks associated with PCI