Results 1 - 10 of 45
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[en] FePt(50 nm) and [FePt(2,3,5 nm)/AlN(1 nm)]n films were prepared by RF magnetron sputtering technique, then annealed at 550 deg. C for 30 min. This work investigates the effect of the number of bilayer repetitions (n) and AlN concentration on structures and magnetic properties of various [FePt/AlN]n multilayers. The highest coercivities of [FePt/AlN]n multilayers were obtained when n was given as 8. The grain sizes of [FePt/AlN]n films were increased with increasing n. Introducing the non-magnetic AlN not only hindered the growth of FePt particles, but also reduced the intergrain exchange interactions of the [FePt/AlN]n films. And the intergrain interactions were decreased with increasing AlN concentration
[en] FePt and FePt/C thin films were prepared by RF magnetron sputtering, then post-annealed in vacuum. The as-deposited films were in disordered state, and the ordered L10 structure was obtained by post-annealing at 550 deg. C for 30 min. Superlattice peaks (0 0 1) and (1 1 0) can be found in the X-ray diffraction pattern of FePt and FePt/C films, which indicate that the FCC phase has been partially transformed into L10 phase. As the thickness of C layer increased from 1 to 3 nm, the coercivities of the FePt/C multilayer decreased from 6.3 to 1.8 kOe, which indicated that thicker carbon layers in the sample would produce a higher activation energy barrier for the disorder-order transformation. With increasing the C concentration, the grain size and intergrain interactions of FePt/C multilayer films were decreased
[en] In this note, the problem of control for a class of chaotic systems is studied. Only partial information of the systems states is known. First, an adaptive observer is designed to ensure the corresponding error system asymptotically stable. Then, based on the states obtained by the above observer, a nonlinear state feedback controller is constructed for the chaotic system, which, according to the input to state stable (ISS) principal, guarantees the closed-loop chaotic system is asymptotically stable. A numerical example is included to show the effectiveness of the proposed techniques
[en] Frequency analysis of neuronal oscillation is very important for understanding the neural information processing and mechanism of disorder in the brain. This Letter addresses a new method to analyze the neuronal population oscillations with empirical mode decomposition (EMD). Following EMD of neuronal oscillation, a series of intrinsic mode functions (IMFs) are obtained, then Hilbert transform of IMFs can be used to extract the instantaneous time frequency structure of neuronal oscillation. The method is applied to analyze the neuronal oscillation in the hippocampus of epileptic rats in vivo, the results show the neuronal oscillations have different descriptions during the pre-ictal, seizure onset and ictal periods of the epileptic EEG at the different frequency band. This new method is very helpful to provide a view for the temporal structure of neural oscillation
[en] Quantum entanglement provides a contemporary secure channel for information communication, and the entanglement swapping builds newly entanglement on the previous isolate particles without direct interaction. In the paper, a novel-layered quantum communication path protocol cross multiple participants based on entanglement swapping is proposed, in which the communication path from sender to receiver across multiple intermediate nodes is constructed, and the constructed quantum channel is served for the information exchange. The present protocol can transmit message from sender to receiver via entanglement swapping. The presented protocol is useful for long-distance quantum information communication, significant to quantum network design and plan.
[en] We study the propagation and interaction of ion-acoustic solitary waves in a simple two-dimensional plasma by using the extended Poincare-Lighthill-Kuo perturbation method. We consider the interaction between two ion-acoustic solitary waves with different propagation directions in such a system, and obtain two Korteweg-de Vries equations for small but finite amplitude solitary waves along both ξ and η trajectories. The effects of the ratio of ion temperature σ, the ratio of heat capacity γ and the colliding angle α on the amplitude, the width of the new nonlinear wave created by the collision between two solitary waves are studied. The effects of these parameters on both the colliding solitary waves are examined as well. It is found that all the above-mentioned parameters have significant effects on the properties of these nonlinear waves. (authors)
[en] Linear dispersion relation for linear wave and a Kadomtsev-Petviashvili (KP) equation for nonlinear wave are given for the unmagnetized two-ion-temperature cold dusty plasma with many different dust grain species. The numerical results of variations of linear dispersion with respect to the different dust size distribution are given. Moreover, how the amplitude, width, and propagation velocity of solitary wave vary vs different dust size distribution is also studied numerically in this paper. (physics of gases, plasmas, and electric discharges)
[en] In this study, we examined the sorption and desorption behavior of U(VI) on/from a Chinese bentonite in the solid-liquid system using batch experiments, and the influence of pH, ionic strength and humic acid (HA) on the sorption-desorption hysteresis in the solid-liquid system were quantitatively calculated. It was revealed that the hysteresis was enhanced with increasing pH and increasing ionic strength. HA promoted the sorption, but lower the sorption-desorption hysteresis. Meanwhile, hysteresis in ternary bentonite-HA-U system was found to be higher than that in bentonite-U-HA system, indicating different sorption structures formed because of different addition sequence. (author)
[en] The sorption and desorption of uranium(VI) on GMZ bentonite was investigated as functions of contact time, pH, ionic strength, foreign ions, HSs and initial U(VI) using batch experiments. It is revealed that the sorption strongly depended on pH, cations (Li"+, Na"+ and K"+) and anions (CO_3"2"-, SO_4"2"- and PO_4"3"-). HA benefits the sorption at pH <7.0, while inhibited the sorption at higher pH. Moreover, the hysteresis occurred in the sorption-desorption process in the presence/absence of humic substances. The results could provide data base for the safety assessment of the deep geological disposal repository of high radioactive waste. (author)
[en] Selenium is both a nutrient and a toxin. Selenium—especially organic selenium—is a core component of human nutrition. Thus, it is very important to measure selenium in biological samples. The limited sensitivity of conventional XRF hampers its widespread use in biological samples. Here, we describe the use of high-energy (100 kV, 600 W) linearly polarized beam energy-dispersive X-Ray fluorescence spectroscopy (EDXRF) in tandem with a three-dimensional optics design to determine 0.1–5.1 μg g"−"1 levels of selenium in biological samples. The effects of various experimental parameters such as applied voltage, acquisition time, secondary target and various filters were thoroughly investigated. The detection limit of selenium in biological samples via high-energy (100 kV, 600 W) linearly polarized beam energy-dispersive X-ray fluorescence spectroscopy was decreased by one order of magnitude versus conventional XRF (Paltridge et al., 2012) and found to be 0.1 μg/g. To the best of our knowledge, this is the first report to describe EDXRF measurements of Se in biological samples with important implications for the nutrition and analytical chemistry communities. - Highlights: • The high-energy (100 kV, 600 W) linearly polarized beam energy-dispersive X-Ray fluorescence spectroscopy (EDXRF) was used to determine 0.1−5.1 μg g"−"1 levels of selenium in biological samples. • High-pressure pressed powder pellet technique (1500 kN) is used for sample preparation. • The detection limit of selenium in biological samples found to be 0.1 μg/g.