A sol-gel method for growing superconducting MgB2 films

In this paper we report a new sol-gel method for the fabrication of MgB2 films. Polycrystalline MgB2 films were prepared by spin-coating a precursor solution of Mg(BH_4)_2 diethyl ether on (001)Al2O3 substrates followed with annealing in Mg vapor. In comparison with the MgB2 films grown by other techniques, our films show medium qualities including a superconducting transition temperature of Tc ~ 37 K, a critical current density of Jc(5 K, 0 T) ~ 5 {\times} 10^6 A cm^{-2}, and a critical field of H_{c2}(0) ~ 19 T. Such a sol-gel technique shows potential in the commercial fabrication of practically used MgB2 films as well as MgB2 wires and tapes.Comment: 8 pages, 5 figure

Formation of MgB2 at low temperatures by reaction of Mg with B6Si

Formation of MgB2 by reactions of Mg with B6Si and Mg with B were compared, the former also producing Mg2Si as a major product. Compared to the binary system, the ternary reactions for identical time and temperature were more complete at 750 C and below, as indicated by higher diamagnetic shielding and larger x-ray diffraction peak intensities relative to those of Mg. MgB2 could be produced at temperatures as low as 450 C by the ternary reaction. Analyses by electron microscopy, x-ray diffraction, and of the upper critical field show that Si does not enter the MgB2 phase.Comment: Submitted to Supercond. Sci. Techno

Solenoidal Coils Made from Monofilamentary and Multifilamentary MgB2 strands

Three solenoids have been wound and with MgB2 strand and tested for transport properties. One of the coils was wound with Cu-sheathed monofilamentary strand and the other two with a seven filament strand with Nb-reaction barriers, Cu stabilization, and an outer monel sheath. The wires were first S-glass insulated, then wound onto an OFHC Cu former. The coils were then heat treated at 675C/30 min (monofilamentary strand) and 700C/20 min (multifilamentary strand). Smaller (1 m) segments of representative strand were also wound into barrel-form samples and HT along with the coils. After HT the coils were epoxy impregnated. Transport Jc measurements were performed at various taps along the coil lengths. Measurements were made initially in liquid helium, and then as a function of temperature up to 30 K. Homogeneity of response along the coils was investigated and a comparison to the short sample results was made. Each coil contained more than 100 m of 0.84-1.01 mm OD strand. One of the 7 strand coils reached 222 A at 4.2 K, self field, with a Jc of 300 kA/cm2 in the SC and a winding pack Je of 23 kA/cm2. At 20 K these values were 175 kA/cm2 and 13.4 kA/cm2. Magnet bore fields of 1.5 T and 0.87 T were achieved at 4.2 K and 20 K, respectively. The other multifilamentary coil gave similar results.Comment: 22 pages, 8 figures, 2 table

Comparison of tubularized incised plate urethroplasty and onlay island flap urethroplasty techniques in the repair of primarily proximal hypospadias

PubMed ID: 28976350OBJECTIVES: To compare the success of the 'tubularized incised plate urethroplasty' (TIPU)' and 'Onlay island flap urethroplasty' (OIFU) techniques for the repair of primary proximal hypospadias. MATERIAL AND METHODS: A retrospective evaluation was made of the medical records of 68 patients with primary, non-complicated hypospadias, who were operated on in the Department of Urology, Ministry of Heal- th Ankara Education and Research Hospital, between January 1997 and December 2012. Patients who underwent hypospadias surgery with TIPU were labelled as Group 1 and the OIFU technique as Group 2. Patient age, native meatus localization, operation time, diversion type, surgical success and complication rates were all assessed. Surgical success was evaluated with direct vision of voiding and uroflowmetry at the time of catheter removal, then at 2 weeks, 6 weeks, 6 months and 1 year. RESULTS: Group 1 consisted of 43 patients and Group 2 of 25 patients. The mean age of patients was 6.4±3.1 years in Group 1 and 8.0±4.6 years in Group 2 (p=0.09). The mean operating time was significantly lower in Group 1. (Group 1- 104.8±16.8 min, Group 2-125.4±24.7min; p<0.001) The distribution of meatus localization was similar in both groups. At 1 year postoperatively, urethrocutaneous fistula was the only complication and the definitive success rates were 81.6% in Group 1 and 72% in Group 2. CONCLUSION: Despite less frequent usage since the description and popularization of TIPU for proximal hypospadias repair, OIFU remains a valuable technique as a single-stage procedure in cases where the urethral plate is insufficient. Currently, both TIPU and OIFU are used successfully in the treatment of patients with proximal hypospadias

ANOMALOUS INCREASES IN THE CRITICAL CURRENTS OF MULTIFILAMENTARY NB3SN WIRES PREPARED BY THE BRONZE ROUTE

Several heat treatment processes have been suggested to improve the critical currents of multifilamentary Nb3Sn wires prepared by the bronze route1. In this paper we describe the results obtained on wires heat treated under high pressure argon gas. This heat treatment process improves both the mechanical2 and the electrical properties by suppressing the formation of Kirkendall3 porosity which, in turn, enhances the Nb3Sn layer growth. The latter effect results in anomalous increases in the overall critical current density of the wires

ANOMALOUS INCREASES IN THE CRITICAL CURRENTS OF MULTIFILAMENTARY Nb3Sn WIRES PREPARED BY THE BRONZE ROUTE

Plusieurs procédés de traitement thermique ont été proposés pour améliorer les courants critiques des fils multifilamentaires de Nb3Sn préparés par la voie bronze. Dans ce papier nous décrivons les résultats obtenus avec des fils traités à chaud sous argon à haute pression. Cette opération de traitement thermique améliore à la fois les propriétés mécaniques et électriques, en supprimant la formation de porosités de Kirkendall ce qui augmente la croissance des couches de Nb3Sn. Ceci a pour effet une augmentation importante des courants critiques dans les fils.Several heat treatment processes have been suggested to improve the critical currents of multifilamentary Nb3Sn wires prepared by the bronze route1. In this paper we describe the results obtained on wires heat treated under high pressure argon gas. This heat treatment process improves both the mechanical2 and the electrical properties by suppressing the formation of Kirkendall3 porosity which, in turn, enhances the Nb3Sn layer growth. The latter effect results in anomalous increases in the overall critical current density of the wires