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CV Tomy D Pal SS Banerjee S Ramakrishnan AK Grover S Bhattacharya MJ Higgins G Balakrishnan McK Paul 《Pramana》2002,58(5-6):925-935
The weakly pinned single crystals of the hexagonal 2H-NbSe2 compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder
transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of
the peak effect phenomenon in three crystals of 2H-NbSe2, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of
a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability
effects and pinning. 相似文献
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Alberti G Brunet E Dionigi C Juanes O de La Mata MJ Rodríguez-Ubis JC Vivani R 《Angewandte Chemie (International ed. in English)》1999,38(22):3351-3353
The hydrophilic oxygen atoms of polyethylenoxide chains inserted as pillars in gamma-zirconium phosphate form hydrogen bonds with the acid groups of the host. As a result the pillars are almost perpendicular to the gamma layers. Upon changing the pH level of the supernatant solution the hydrogen bonds are broken and the pillars become almost perpendicular to the layers (shown schematically). Thus there is a reversible enlargement-shortening of the interlayer space. 相似文献
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F.?Canet C.?BellouardEmail author S.?Mangin C.?Chatelain C.?Senet R.?Siebrecht V.?Leiner M.?Piecuch 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,34(4):381-394
A study of exchange bias phenomenon in ferrimagnetic /ferromagnetic FeGd/ FeSn bilayers is presented. The amorphous FeSn and FeGd alloys have been grown by co-evaporation. Specific growth conditions allow to induce an uniaxial anisotropy in both alloys in a parallel direction. After saturation of the bilayers under a positive field, the hysteresis loop of one of the layer is shifted towards a positive field H
E
. The sign of the exchange bias field H
E
is shown to be due to the antiferromagnetic coupling between the net magnetizations of both alloys. The field H
E
is studied as a function of the thickness of each layer and of the temperature. Using ac-susceptibility measurements and polarized neutron reflectometry, it is shown that the reversal of magnetization of the bilayers is dominated by the presence of a domain wall at the interface. This exchange bias system is shown to act as a potential well for the magnetic domain wall. Within this assumption and thanks to a precise magnetic characterization of each alloy, the evolution of H
E
with the thickness of the layers is well reproduced using simple one-dimensional analytical models for the domain wall or a more elaborate numerical approach.Received: 20 February 2003, Published online: 9 September 2003PACS:
75.60.Ch Domain walls and domain structure - 75.70.-i Magnetic properties of thin films, surfaces, and interfaces - 75.25.+z Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source X-ray scattering, etc.) 相似文献
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Hermann E. Posch Marc J. P. Leiner Otto S. Wolfbeis 《Fresenius' Journal of Analytical Chemistry》1989,334(2):162-165
Summary This work describes the development of the first optical pH-sensor capable of measuring pH-values in the 0–7 range. The pH-sensitive material consists of fibrous amino-ethyl cellulose onto which fluorescein and eosin were covalently immobilised. Fluorescein was immobilised via its isothiocyanate, and immobilised eosin was obtained by bromination of the immobilised fluorescein. The material thus obtained was mechanically fixed at the end of a bifurcated optical fibre bundle. Fluorescence was excited at 490 nm and measured at >540 nm. The accuracy of the sensor is ±0.05 pH units, its response time ranges from 25 to 30 s. Practically no signal loss was observed upon constant illumination over periods of more than 15 h.
Entwicklung einer Magensonde: Eine Optode für den pH-Bereich 0–7相似文献
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Dipl.-Ing. F. Peper Priv.-Doz. Dr.-Ing. W. Leiner Prof. Dr.-Ing. M. Fiebig 《Heat and Mass Transfer》1995,30(5):313-320
The drying performance and the forces generated by a pair of radial jets impinging on a plane surface are studied experimentally and compared with a pair of in-line (axial) jets. The reattachment rings of the radial jets are visualized by liquid-crystal-thermography. The results of the drying experiments are presented in terms of Sherwoodnumbers. The results of the surface force measurements are presented in terms of force coefficients. The effects of flow exit angle, exit velocity, horizontal nozzle spacing and vertical nozzle to surface distance on mass transfer and net surface force are discussed. Results show that drying performance of a pair of radial jets with an exit angle towards the surface of 10° is 18% higher than that of a pair of in-line jets. The surface force of impinging radial jets depends on the exit angle. A global pressure force on the surface is typical for jets directed towards the surface, while a global lifting force is found when the jet is initially directed away from the surface. Radial jets have a high potential in drying applications for force sensitive products and when high drying rates and/or small suction forces are of interest. 相似文献
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