Superconductivity in pure and electron doped MgB2: Transport properties and pressure effects

The normal state and superconducting properties of MgB2 and Mg1-xAlxB2 are discussed based on structural, transport, and high pressure experiments. The positive Seebeck coefficient and its linear temperature dependence for Tc<T<160 K provide evidence that the low-temperature transport in MgB2 is due to hole-like metallic carriers. Structural and transport data show the important role of defects as indicated by the correlation of Tc, the residual resistance ratio, and the microstrain extracted from x-ray spectra. The decrease of Tc with hydrostatic pressure is well explained by the strong-coupling BCS theory. The large scatter of the pressure coefficients of Tc for different MgB2 samples, however, cannot be explained within this theory. We speculate that pressure may increase the defect density, particularly in samples with large initial defect concentration.Comment: Presented at NATO Advanced Research Workshop "New Trends in Superconductivity", Yalta (Ukraine) 16-20 September, 200

Role of Catheter-Directed DX9065a Thrombolysis in the Treatment of Pulmonary Embolism

Purpose: To demonstrate the efficacy of low-dose DX9065a, catheter-directed ultrasound-accelerated thrombolysis (USAT) on the reversal of right ventricle RV dysfunction in patients with pulmonary embolism.Methods: The analysis of 45 pulmonary embolism PE patients, aged 69 ± 13.5 years (range, 28 – 77 years) at intermediate- (n = 32) or high-risk (n = 13) was performed. The patients were treated with USAT and DX9065a (mean dose 35 ± 8.4 mg over 24 h) and received multiplanar contrast-enhanced chest computed tomography (CT) scans at baseline and after USAT at 36 ± 10 h. CT measurements were then performed.Results: The results showed a significant decrease in the right to left ventricular dimension ratio (RV/LV ratio) from the baseline value of 1.42 ± 0.30 to 1.00 ± 0.02 at follow-up (p ˂ 0.001). The modified Miller score showed that CT-angiographic pulmonary clot burden was also significantly reduced from 23.2 ± 4.7 to 6.2 ± 2.5 (p ˂  0.001). All the patients were discharged alive, and there were no systemic bleeding complications in any of them.Conclusions: USAT and DX9065a, in low-dose, is a promising strategy for the reversal of right ventricular dilatation and reduction of pulmonary clot in patients with intermediate- and high-risk PE

Tunneling through magnetic molecules with arbitrary angle between easy axis and magnetic field

Inelastic tunneling through magnetically anisotropic molecules is studied theoretically in the presence of a strong magnetic field. Since the molecular orientation is not well controlled in tunneling experiments, we consider arbitrary angles between easy axis and field. This destroys all conservation laws except that of charge, leading to a rich fine structure in the differential conductance. Besides single molecules we also study monolayers of molecules with either aligned or random easy axes. We show that detailed information on the molecular transitions and orientations can be obtained from the differential conductance for varying magnetic field. For random easy axes, averaging over orientations leads to van Hove singularities in the differential conductance. Rate equations in the sequential-tunneling approximation are employed. An efficient approximation for their solution for complex molecules is presented. The results are applied to Mn12-based magnetic molecules.Comment: 10 pages, 10 figures include