5,450 research outputs found
Current-Induced Resonant Motion of a Magnetic Vortex Core: Effect of Nonadiabatic Spin Torque
The current-induced resonant excitation of a magnetic vortex core is
investigated by means of analytical and micromagnetic calculations. We find
that the radius and the phase shift of the resonant motion are not correctly
described by the analytical equations because of the dynamic distortion of a
vortex core. In contrast, the initial tilting angle of a vortex core is free
from the distortion and determined by the nonadiabaticity of the spin torque.
It is insensitive to experimentally uncontrollable current-induced in-plane
Oersted field. We propose that a time-resolved imaging of the very initial
trajectory of a core is essential to experimentally estimate the
nonadiabaticity.Comment: 4 pages, 4 figure
Stability of hydrogenation states of graphene and conditions for hydrogen spillover
The hydrogen spillover mechanism has been discussed in the field of hydrogen storage and is believed to have particular advantage over the storage as metal or chemical hydrides. We investigate conditions for practicality realizing the hydrogen spillover mechanism onto carbon surfaces, using first-principles methods. Our results show that contrary to common belief, types of hydrogenation configurations of graphene (the aggregated all-paired configurations) can satisfy the thermodynamic requirement for room-temperature hydrogen storage. However, the peculiarity of the paired adsorption modes gives rise to a large kinetic barrier against hydrogen migration and desorption. It means that an extremely high pressure is required to induce the migration-derived hydrogenation. However, if mobile catalytic particles are present inside the graphitic interstitials, hydrogen migration channels can open and the spillover phenomena can be realized. We suggest a molecular model for such a mobile catalyst which can exchange hydrogen atoms with the wall of graphene.open151
Current-induced domain wall motion in a nanowire with perpendicular magnetic anisotropy
We study theoretically the current-induced magnetic domain wall motion in a
metallic nanowire with perpendicular magnetic anisotropy. The anisotropy can
reduce the critical current density of the domain wall motion. We explain the
reduction mechanism and identify the maximal reduction conditions. This result
facilitates both fundamental studies and device applications of the current-
induced domain wall motion
Separation of Phosvitin from Egg Yolk without Using Organic Solvents
The objective of this study was to develop a new method to separate phosvitin from egg yolk without using organic solvents. Phosvitin was extracted from yolk granules using 10% NaCl or 10% (NH4)2SO4 (final concentration) and then treated with heat to precipitate the lipoproteins from the extracted solution. The optimal pH for the phosvitin extraction from yolk granules was determined, and the iron-binding ability of the extracted phosvitin (final product) was tested. Adding 10% (NH4)2SO4 disrupted the granules, and the subsequent thermal treatment at 90°C for 1 h precipitated low density and high density lipoproteins, which enabled separation of phosvitin by centrifugation. The phosvitin concentration in the extract was significantly higher when the pH of the solution was adjusted to pH ≥9. The purity and recovery rate of phosvitin at the end of the separation process were approximately 78% and 56%, respectively. The separated phosvitin was confirmed to have ferrous and ferric iron binding ability. The advantages of this new method compared with the traditional methods include no organic solvents and high-priced equipment are needed for the separation. Also, this method is more environment and consumer friendly than that of the traditional methods
Mild and Nondestructive Chemical Modification of Carbon Nanotubes (CNTs): Direct Friedel-Crafts Acylation Reaction
A situation-aware cross-platform architecture for ubiquitous game
Multi-player online games (MOGs) are popular in these days. However, contemporary MOGs do not really support ubiquity in the sense that a seamless service across heterogeneous hardware platforms is not provided. This paper presents the architecture of the cross-platform online game, which provides a service to users from heterogeneous platforms and is equipped with a situation-aware capability for enabling the users to seamlessly move between heterogeneous platforms. The experimental results through the prototype implementations show the feasibility of the situation-aware cross-platform game
Satellite Clustering for Non-Terrestrial Networks: Concept, Architectures, and Applications
Recently, mega-constellations with a massive number of low Earth orbit (LEO)
satellites are being considered as a possible solution for providing global
coverage due to relatively low latency and high throughput compared to
geosynchronous orbit satellites. However, as the number of satellites and
operators participating in the LEO constellation increases, inter-satellite
interference will become more severe, which may yield marginal improvement or
even decrement in network throughput. In this article, we introduce the concept
of satellite clusters that can enhance network performance through satellites'
cooperative transmissions. The characteristics, formation types, and
transmission schemes for the satellite clusters are highlighted. Simulation
results evaluate the impact of clustering from coverage and capacity
perspectives, showing that when the number of satellites is large, the
performance of clustered networks outperforms the unclustered ones. The viable
network architectures of the satellite cluster are proposed based on the 3GPP
standard. Finally, the future applications of clustered satellite networks are
discussed.Comment: 7 pages, 7 figures, 1 table, submitted to IEEE Vehicular Technology
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