10 research outputs found
High current-carrying capability in c-axis-oriented superconducting MgB2 thin films
In high-quality c-axis-oriented MgB2 thin films, we observed high critical
current densities (Jc) of 16 MA/cm^2 at 15 K under self fields comparable to
those of cuprate high-temperature superconductors. The extrapolated value of Jc
at 5 K was estimated to be 40 MA/cm^2. For a magnetic field of 5 T, a Jc of 0.1
MA/cm^2 was detected at 15 K, suggesting that this compound would be a very
promising candidate for practical applications at high temperature and lower
power consumption. The vortex-glass phase is considered to be a possible
explanation for the observed high current-carrying capability.Comment: 3 pages and 4 figures, to be published in Physical Review Letter
Microstructure and pinning properties of hexagonal-disc shaped single crystalline MgB2
We synthesized hexagonal-disc-shaped MgB2 single crystals under high-pressure
conditions and analyzed the microstructure and pinning properties. The lattice
constants and the Laue pattern of the crystals from X-ray micro-diffraction
showed the crystal symmetry of MgB2. A thorough crystallographic mapping within
a single crystal showed that the edge and c-axis of hexagonal-disc shape
exactly matched the (10-10) and the (0001) directions of the MgB2 phase. Thus,
these well-shaped single crystals may be the best candidates for studying the
direction dependences of the physical properties. The magnetization curve and
the magnetic hysteresis for these single crystals showed the existence of a
wide reversible region and weak pinning properties, which supported our single
crystals being very clean.Comment: 5 pages, 3 figures. submitted to Phys. Rev.
Substitution for Cu in the electron-doped infinite-layer superconductor Sr0.9La0.1CuO2, Ni reduces Tc much faster than Zn
We report on the effect of substitution for Cu on Tc of electron-doped
infinite-layer superconductors Sr0.9La0.1Cu1-xRxO2, R = Zn and Ni. We found
that Tc was nearly constant until x = 0.03 for R = Zn, while superconductivity
was nearly suppressed for x = 0.02 with dTc/dx = 20 K/% for R = Ni. This
behavior is very similar to that of conventional superconductors. These
findings are discussed in terms of the superconducting gap symmetry in the
cuprate superconductors including another electron-doped superconductor,
(Nd,Ce)2CuO4-y.Comment: 5 pages and 2 EPS figures, [email protected] for material reques
A Magnetization and Microwave Study of Superconducting MgB2
We report magnetic field dependent magnetization and microwave impedance
measurements on a MgB2 superconductor prepared by high pressure synthesis. We
find that the upper critical field is linearly dependent on temperature near Tc
and the dc irreversibility field exponent is ~1.4. The microwave data display
an excess surface resistance below Tc which is neither observed in low Tc nor
in high temperature superconductors (HTSC). The real part of the complex
conductivity, sigma1, shows a huge maximum below Tc and the imaginary part,
sigma2, is linear for temperatures less than 20 K, which can not be simply
accounted for by the weak coupling BCS model with an s-wave superconducting
order parameter. We speculate that this may be due to the two gaps reported by
other studies. Unlike measurements on the high temperature superconducting
cuprates, we find no evidence of weak-links in the superconducting state. By
inverting the magnetic field dependent impedance data, we find a vortex
depinning frequency that decreases with increasing magnetic field and evidence
for an anisotropic upper critical magnetic field.Comment: Submitted to Phys. Rev. B. 19 pages PD
Basic Superconducting-State Parameters and Their Influence on the Flux Pinning in Homologous Series HgBa2Can−1CunO2n+2+x
Detection of the superconducting transition and magnetic flux trapping in a niobium micro-ring by using micro-Hall sensors
Prognostic factors in primary diffuse large B-cell lymphoma of adrenal gland treated with rituximab-CHOP chemotherapy from the Consortium for Improving Survival of Lymphoma (CISL)
<p>Abstract</p> <p>Background</p> <p>The objective of this study was to identify prognostic factors for survival in patients with primary diffuse large B-cell lymphoma (DLBCL) of the adrenal gland.</p> <p>Methods</p> <p>Thirty one patients diagnosed with primary adrenal DLBCL from 14 Korean institutions and treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone) were analyzed.</p> <p>Results</p> <p>Complete remission (CR) and overall response rate after R-CHOP chemotherapy were 54.8% and 87.0%. The 2-year estimates of overall survival (OS) and progression-free survival (PFS) were 68.3% and 51.1%. In patients achieving CR, significant prolongations of OS (<it>P</it> = 0.029) and PFS (<it>P</it> = 0.005) were observed. Ann Arbor stage had no influence on OS. There was no significant difference in OS between patients with unilateral involvement of adrenal gland and those with bilateral involvement. When staging was modified to include bilateral adrenal involvement as one extranodal site, early stage (I or II) significantly correlated with longer OS (<it>P</it> = 0.021) and PFS (<it>P <</it>0.001).</p> <p>Conclusions</p> <p>Contrary to prior reports, our data suggests that outcomes of primary adrenal DLBCL are encouraging using a regimen of R-CHOP, and that achieving CR after R-CHOP is predictive of survival. Likewise, our modified staging system may have prognostic value.</p