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- MAGNUSSON, J, et al.
(författare)
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FLUX PINNING IN YBA2CU3O7 THIN-FILMS GROWN BY DC MAGNETRON SPUTTERING
- 1992
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Ingår i: Cryogenics (Guildford). - : Elsevier BV. - 0011-2275 .- 1879-2235. ; 32, s. 1084-1088
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Tidskriftsartikel (refereegranskat)abstract
- Thin films of YBa2Cu3O7 (YBCO) were deposited on single crystalline LaAlO3 substrates using d.c. magnetron sputtering. The quality of the films has been assessed by X-ray diffraction; YBa2Cu3O7 grows epitaxially with the c-axis parallel to the substrate normal. For some choices of the deposition parameters in the sputtering process, it was found that secondary phases were precipitated in the films. By a deliberate choice of deposition parameters, semi-coherently grown Y2O3 (yttria) inclusions could be obtained. They had square platelet or cubical shapes with sizes from 5 - 20 nm and thickness approximately 10 nm. The superconducting properties of the YBa2Cu3O7 films were investigated using SQUID magnetometry. Magnetization measurements on films with different densities of semicoherent Y2O3 inclusions indicate an enhanced flux pinning capability with increasing inclusion density.
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| 2. |
- NORLING, P, et al.
(författare)
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MAGNETIC-RELAXATION OF INTERGRANULAR CRITICAL-STATE IN SINTERED YBA2CU3O7-DELTA
- 1994
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Ingår i: Physica. C, Superconductivity. - : Elsevier BV. - 0921-4534 .- 1873-2143. ; 221, s. 169-176
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Tidskriftsartikel (refereegranskat)abstract
- The relaxation of the zero-field-cooled magnetisation of three sintered samples of YBa2Cu3O7-delta has been measured at low fields. Special attention was paid to the low-field regime where the motion of intergranular vortices is dominating the decay of the magnetisation. From the measured data the apparent activation energy for flux jumps, U0, was calculated. The extracted values fall in the range 0.6-2 eV, considerably higher than what has been found for the intragranular flux creep but in the same range as reported by others for intergranular creep. The samples showed somewhat different behaviours and the sample with the most homogeneous morphology had the lowest value of U0. This can be explained within theories for pinning in granular superconductors.
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| 3. |
- NISKANEN, K, et al.
(författare)
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ANTI-MEISSNER EFFECT AND LOW-FIELD MAGNETIC-RELAXATION IN SINTERED BI-2212
- 1994
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 194, s. 1549-1550
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Tidskriftsartikel (refereegranskat)abstract
- A detailed study of the low field magnetic properties of some sintered Bi-2212 samples has been performed. For sufficiently low applied magnetic fields, typically for fields H < 0.2 Oe, the field-cooled magnetisation becomes positive at some temperature below T(C) (anti-Meissner effect), contrary to the usual Meissner effect. The field dependence of this effect is comparable to the predicted behaviour for a system in an orbital glass state. Additionally, the relaxation of the zero-field-cooled magnetisation displays an unexpected field dependence, the relaxation rate S = partial-derivative M/partial-derivative log(t) increases as H(alpha) with alpha almost-equal-to 0.9 at very low fields. In contrast to the behaviour found in sintered YBCO, this result is not accounted for in conventional flux creep models, where the prediction is alpha greater-than-or-equal-to 2.
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| 5. |
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| 6. |
- Wang, L P, et al.
(författare)
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Auditory function after spinal anesthesia
- 1993
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Ingår i: Regional Anesthesia. - 0146-521X. ; 18:3, s. 5-162
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To determine the effect of spinal anesthesia using 26-gauge needles on hearing.METHODS: Eighteen male patients undergoing transurethral resection of the prostate (TURP) or other transurethral procedures under spinal or epidural anesthesia were studied prospectively to reveal possible auditory side effects of dural puncture or absorption of irrigation fluid to the blood stream. Measurement of auditory function by pure tone, Bekesy and speech audiometry, and measurement of serum concentrations of sodium, potassium, urea, and glucose were performed preoperatively and postoperatively. Clinical examination of cranial nerve functions was performed postoperatively.RESULTS: No mean change in hearing ability was seen in any group. One patient had severe, transient, low-frequency hearing loss with simultaneous severe postdural puncture headache. A statistically significant postoperative fall in serum osmolarity was noted in the epidural TURP group.CONCLUSION: Transient, severe hearing loss may still occur after spinal anesthesia using a 26-gauge needle. Minor hearing loss does not seem to be a problem with this needle size.
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