Search results for "Wall"
showing 10 items of 970 documents
Quantitative measurements of magnetic stray field dynamics of Permalloy particles in a photoemission electron microscopy
2010
By example of a Permalloy particle (40 × 40 μm(2) size, 30 nm thickness) we demonstrate a procedure to quantitatively investigate the dynamics of magnetic stray fields during ultrafast magnetization reversal. The measurements have been performed in a time-resolving photoemission electron microscope using the X-ray magnetic circular dichroism. In the particle under investigation, we have observed a flux-closure-dominated magnetic ground structure, minimizing the magnetic stray field outside the sample. A fast magnetic field pulse introduced changes in the micromagnetic structure accompanied with an incomplete flux closure. As a result, stray fields arise along the edges of domains, which cau…
Influence of Axial Pressure on Electric Properties of PLuN and 0.6PLuN–0.4PSN Ceramics
2005
The dielectric, pyroelectric and hysteresis loops measurements of PLuN and 0.6PLuN–0.4PSN ceramics, stress-free or under the stress (0–1.5 kbar), have been carried out. It is shown that uniaxial pressure shifts the phase transformation and decreases the thermal hysteresis of the electric permittivity and the field-polarization hysteresis. These changes of properties could be connected with domain wall motion and with switching of the polarization under uniaxial pressure.
Ferroelectricity and piezoelectricity in soft biological tissue: Porcine aortic walls revisited
2017
Recently reported piezoresponse force microscopy (PFM) measurements have proposed that porcine aortic walls are ferroelectric. This finding may have great implications for understanding biophysical properties of cardiovascular diseases such as arteriosclerosis. However, the complex anatomical structure of the aortic wall with different extracellular matrices appears unlikely to be ferroelectric. The reason is that a prerequisite for ferroelectricity, which is the spontaneous switching of the polarization, is a polar crystal structure of the material. Although the PFM measurements were performed locally, the phase-voltage hysteresis loops could be reproduced at different positions on the tis…
THE PETROGRAPHY AND CHEMISTRY OF THIN-WALLED WARE FROM AN HELLENISTIC- ROMAN SITE AT SEGESTA (SICILY)*
2003
Samples of Roman thin-walled ware from Segesta (northwestern Sicily), dating back to the early Imperial period, were studied by optical microscopy (OM) and Neutron Activation Analysis (NAA). Up to now, this class of Roman fine tableware has only occasionally been evaluated archaeometrically. Nevertheless, numerous production centres are believed to have been simultaneously active in the western Mediterranean area. Petrographic and chemical data seem to be in agreement with the archaeological hypothesis of local manufacture in Segesta for most of the analysed samples, through a comparison with kiln wasters and local raw materials. The effectiveness of thin-section petrography for determining…
The significance of plasma kinins in intestinal obstruction and peritonitis
1969
The present concept of plasmakinin action suggests that they may also play an important role in the pathophysiology of intestinal obstruction and peritonitis. Since the assay of the kinins is still something of a problem, and since the percursor kallikrein can be determined by a standardized method, we studied the titers of kallikrein in the peripheral and portal circulation in dogs with experimental intestinal obstruction and in patients with these disorders. Significantly higher levels of kallikrein were found in intestinal obstruction, particularly in obstruction with strangulation (Fig. 1).
In situ study of the phase transition in Bi2Ti4O11
1995
Abstract The paraelectric ⇌ antiferroelectric phase transition of the compound Bi 2 Ti 4 O 11 is studied in situ by electron diffraction and electron microscopy. The transition is reversible and clearly second order. Above T c faint streaking at the superlattice positions persists. In the low-temperature phase, antiphase boundaries with a displacement vector R = 1/2[101] are revealed; they show a finite width, suggesting a gradual displacement of the Bi atoms at the transition. A model for the domain wall configuration is proposed, based on the influence of the lone pairs of Bi 3+ ions at the transition.
Dependence of Exciton Mobility on Structure in Single-Walled Carbon Nanotubes
2010
Optically generated excitons in semiconducting single-walled carbon nanotubes (SWCNTs) display substantial diffusional mobility. This property allows excitons to encounter ∼104 carbon atoms during their lifetime and accounts for their efficient deactivation by sparse quenching sites. We report here experimental determinations of the mobilities of optically generated excitons in 10 different (n,m) species of semiconducting SWCNTs. Exciton diffusional ranges were deduced from measurements of stepwise photoluminescence quenching in selected individual SWCNTs coated with sodium deoxycholate surfactant and immobilized in agarose gel. A refined data analysis method deduced mean exciton ranges fro…
Stochastic seismic analysis of hydrodynamic pressure in dam reservoir systems
2002
Hydrodynamic seismic-induced pressure requires careful consideration in the aseismic design of dams. Effects induced by earthquake excitation may cause many-fold increments of hydrostatic pressure. In this study earthquake excitation has been modelled by means of random process theory obtaining the response statistics of a dam-reservoir dynamical system. The analysis has been conducted assuming a rigid retaining wall of the reservoir and dissipative fluid. Copyright © 2002 John Wiley & Sons, Ltd.
Unidirectional Magnon-Driven Domain Wall Motion Due to the Interfacial Dzyaloshinskii-Moriya Interaction
2018
We demonstrate a unidirectional motion of a quasiparticle without an explicit symmetry breaking along the space-time coordinate of the particle motion. This counterintuitive behavior originates from a combined action of two intrinsic asymmetries in the other two directions. We realize this idea with the magnon-driven motion of a magnetic domain wall in thin films with interfacial asymmetry. Contrary to previous studies, the domain wall moves along the same direction regardless of the magnon-flow direction. Our general symmetry analysis and numerical simulation reveal that the odd order contributions from the interfacial asymmetry is unidirectional, which is dominant over bidirectional contr…
Geometrically enhanced closed-loop multi-turn sensor devices that enable reliable magnetic domain wall motion
2017
We experimentally realize a sophisticated structure geometry for reliable magnetic domain wall-based multi-turn-counting sensor devices, which we term closed-loop devices that can sense millions of turns. The concept relies on the reliable propagation of domain walls through a cross-shaped intersection of magnetic conduits, allowing for the intertwining of loops of the sensor device. As a key step to reach the necessary reliability of the operation, we develop a combination of tilted wires called the syphon structure at the entrances of the cross. We measure the control and reliability of the domain wall propagation individually for cross-shaped intersections, the syphon geometries, and fin…