| 1. |
- Johansen, T.H., et al.
(författare)
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Transition from elastic to dissipative motion in a magnet-high-Tc superconductor system
- 1991
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 70:12, s. 7496-7499
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Tidskriftsartikel (refereegranskat)abstract
- Using quasistatic harmonic excitations, we have measured the lateral force between a permanent magnet and a Bi-based ceramic high-Tc superconductor (HTSC) for lateral displacement amplitudes down to 1 µm. We find clear evidence for a transition from elastic (nondissipative) to inelastic interaction, and attribute the effect to flux pinning. The crossover amplitude can easily reach several micrometers, with the consequence that the lateral disturbance of a levitated magnet will decay to this amplitude, whereas further damping will be extremely slow. For applications of HTSCs in magnetic bearing systems this can be a very relevant aspect of the interaction, and it can set the limit for precision positioning of levitated objects
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| 2. |
- Yang, Z, et al.
(författare)
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Glycoproteins with Gal alpha 4Gal are absent from human erythrocyte membranes, indicating that glycolipids are the sole carriers of blood group P activities.
- 1994
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Ingår i: The Journal of biological chemistry. - 0021-9258. ; 269:20, s. 14620-4
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Tidskriftsartikel (refereegranskat)abstract
- The antigenic determinants of the blood group P family (P1, P, Pk, and LKE antigens) are chemically based on Gal alpha 4Gal. For human erythrocytes it has been claimed that the majority of P1 determinants are expressed in glycoproteins, mainly band 4.5 (Haselberger, C. G., and Schenkel-Brunner, H. (1982) FEBS Lett. 149, 126-128). In the present work, the existence of Gal alpha 4Gal in glycoproteins of erythrocyte membranes (ghosts) of P1 positive and negative human individuals was carefully analyzed on replicas of sodium dodecyl sulfate-polyacrylamide electrophoresis gels using specific reagents (Escherichia coli HB101/pDC1 expressing the Pap gene and monoclonal antibodies with specificities for P1 and Pk antigens). No binding to glycoproteins was detected with any of these ligands when the ghosts had been pretreated with butanol to remove glycolipids. Therefore, all antigenic determinants of the P blood group family on human red cells are exclusively expressed in glycolipids and are absent from glycoproteins.
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| 3. |
- Yang, Z.J., et al.
(författare)
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Study of flux motion in Bi-based superconductors by a pendulum
- 1992
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Ingår i: Journal of Superconductivity. - 0896-1107 .- 1572-9605. ; 5:2, s. 127-135
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Tidskriftsartikel (refereegranskat)abstract
- Using a computerized mechanical pendulum, we have studied the lateral magnetic flux motion of the Bi-based high-T c superconductors in the quasi-static magnetic field (0.1 Hz) for the range 1 μm to 0.35 mm. The effect of d.c. and a.c. transport currents on the flux motion has also been investigated. We argue that the lateral magnetic stiffness is a measure of the pinning potential of the fluxoids in the superconductors. The pinning energy barrier ε is estimated to be about 0.3 eV based on the stiffness measurements, which is comparable with the data from the YBa2Cu3O7-χ superconductors.
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