Decrement in metastability with Zr nanoparticles inserted in Bi-2223 superconducting system and working principle of hybridization mechanism

This exhaustive study experimentally deals with the role of Zr foreign impurities on the electrical, superconducting and flux pinning properties of the bulk Bi-2223 superconducting compounds by the typical experimental characterization methods such as dc resistivity (rho-T), transport critical current density (J (c) ) and powder X-ray diffraction (XRD) surveys. All the experimental findings show that the curial characteristics, being in charge of the varied attractive and feasible applications, retrograde significantly with the enhancement of the Zr nanoparticles in the Bi-2223 superconducting system due to the presence of two trap levels for mobile holes. This leads to the degradation of the metastability of the superconducting materials. In more detail, based on the dc resistivity and transport critical current density measurements, the Zr additives give rise to the localization problem as a consequence of the change in the dynamics of electron-electron interaction. Thus, the room state conductivity, , and J (c) values retrograde significantly. Similarly, the Zr foreign impurities embedded in the Bi-2223 crystal lattice make the artificial random defects, dislocations and grain boundary weak-interactions in the consecutively stacked layers enhance immediately, and the superconducting Cu-O-2 layers distort especially. Moreover, the XRD investigations including the evidences about the decrement/increment in the c-axis/a-axis length verify the regression of the superconducting properties with the Zr dopant. The main differentiation of the lattice constant parameters stems from aliovalent substitutions (replacement of the divalent Cu by the tetravalent Zr impurties) along with the crystal structure. In other words, the reduction of the electronegativity leads to decrease the mobile hole concentration in the Cu-O-2 consecutively stacked layers. Furthermore, all the decrement parameters are theoretically favored by hybridization mechanism.https://doi.org/10.1007/s10854-015-3839-

Role of Bi/Tm substitution in Bi-2212 system on crystal structure quality, pair wave function and polaronic states

This comprehensive study finds strongly out the crucial variations in the dc electrical resistivity, superconducting, crystal structural and flux pinning mechanisms with the partial replacement of homovalent Tm+3 inclusions by Bi+3 impurity in the active layers of Bi-2212 superconducting material. Materials of type Bi2.1-xTmxSr2.0Ca1.1Cu2.0Oy with molar ratio changes of 0.00 <= x <= 0.30 are prepared by conventional solid-state reaction route in atmospheric pressure and the characterizations are exerted by the bulk density, dc electrical resistivity (rho-T), powder X-ray diffraction (XRD), critical current density (J(c)), scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) experimental measurements. The combination of experimental results evaluated from the bulk density, dc electrical resistivity, XRD and EDX measurements points out that the Tm foreign impurities mostly incorporate successfully into the Bi-2212 crystal lattice. In fact, the EDX investigations verify that the thulium impurities may mostly be substituted for the bismuth sites in the crystal structure. All the experimental results declare that the characteristic features improve regularly with the increment in the Tm impurity level up to x = 0.07 beyond which the properties degrade dramatically. In this respect, the sample with x = 0.07 exhibits highest electrical conductive/metallic characteristics as a consequence of the refinement in the crystal structure quality and connectivity between the superconducting grains, being favored by bulk density and related relative degrees of granularity surveys. Likewise, the material presents the maximum offset-onset critical transition temperature values of 85.61 K-85.85 K due to the increment in the formation of effective and strong electron-phonon coupling probabilities and optimization of mobile hole carrier concentrations in the Cu-O-2 consecutively stacked layers. In other words, the optimum content level leading to transit inherently over-doped nature into optimally doped state strengthens the amplitude of pair wave function for the Bi-2212 material. In more sophisticated interpretations, the presence of optimum dopant in the crystal structure changes the vibrational mode intensities of O (1)CuA1g, B1g phonons and O (2)SrA1g phonon so that the formation possibility of bipolaron out of two polarons increases strongly in a polarizable lattice (polaronic effect). Additionally, the highest self-field J(c) of 95 A/cm(2) confirms the fact that the optimum dopant augments the effective nucleation centers along the intragrain and inter-grain boundaries in the crystal system. Similarly, the material prepared with x = 0.07 presents the smoothest, densest, largest average crystalline distribution, lowest porosity and most uniform surface appearance with the finest connection between the superconducting grains. The XRD results (the increased high phase, c-axis length and average grain size but decreased a-axis length) also show the optimum dopant level of x = 0.07 for Bi-2212 crystal system. All in all, the paper developing a strong methodology about why the characteristic properties improve with the presence of Tm impurity in the Bi-2212 system may be a pioneering research to construct newly, novel and feasible market areas for the Bi-2212 superconducting ceramics in the universe economy. (C) 2018 Elsevier B.V. All rights reserved

Corticosteroid treatment normalizes QTc prolongation and improves heart block in an elderly patient with anti-Ro-positive systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multisystemic disease which potentially involves various organs including the skin, joints, kidneys, liver, hematopoetic system, and serous membranes. It is rarely seen in elderly males. The most common cardiovascular involvement type is pericarditis. Anti-Ro antibodies may be associated with neonatal lupus which causes heart blocks. Recent literature indicates that anti-Ro antibodies may be associated with various rhythm and conduction disturbances in the adulthood. The most common finding associated with anti-Ro antibodies is prolonged corrected QT (QTc) interval. Herein, we present an elderly male patient with anti-Ro-positive SLE associated with prolonged QTc interval and AV blocks that significantly improved after corticosteroid treatment