Results 1 - 10 of 19
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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] 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] The photostability and fluorescence properties of 1,3-diphenylisobenzofuran (DPBF), a popular singlet oxygen (1O2 or 1Δg) trapping-agent used in various solvents, are examined by UV-vis absorption, steady-state and time-resolved fluorescence techniques, as well as laser flash photolysis. DPBF is found to be easily photolyzed even if it is only exposed to the weak daylight in halogen-containing solvents in the absence of singlet oxygen. The photolysis is due to the addition of ·CCl3 (·CHCl2) to DPBF in the absence of oxygen, or ·OOCCl3 (·OOCHCl2) initiated chain polymerization of DPBF in the presence of oxygen. This result suggests that the reported singlet oxygen production in these solvents detected by DPBF was significantly higher than the true value. DPBF in DMF, DMSO, etc., on the other hand, is stable enough to enable fluorescence measurements. The fluorescence quantum yield of DPBF is very high in aprotic solvents and close to unity. The absorption, excitation and emission maxima are only slightly affected by the nature of solvents. The fluorescence lifetime is 5.0±0.3 ns. - Highlights: → We found that DPBF was easily photoxidized in CCl4 or CHCl3 without singlet oxygen. → The fluorescence quantum yield of DPBF is close to unity. → The photolysis is due to the addition of ·CCl3 (·CHCl2) to DPBF in the absence of oxygen. → The absorption, excitation and emission maxima are only slightly affected by solvents.
[en] On the basis of data obtained from China Earthquake Administration and China National Statistics Bureau, this paper focuses on the earthquake disaster loss characteristics in 31 provinces or municipalities of China from 1993 to 2016. The trends of direct economic losses, casualties and affected population are also analyzed by constructing two relative earthquake loss indexes (losses/GDP and losses/E) and employing gray correlation theory. Results show that during the 24 years, without taking Wenchuan Ms8.0 earthquake into account, the direct economic losses exhibit a significant increasing trend while losses/GDP also increases but is not significant. Meanwhile, the injuries and affected population both witness a decline trend but the fatalities show the opposite. According to the correlational degree of each year, 8 years (1995, 1996, 1998, 2003, 2008, 2010, 2013 and 2014) suffered losses of equal or above moderate grade. Regionally, the western China suffered the most accumulative direct economic losses and losses/GDP. However, the ranking results of losses/E demonstrate that the central China is the most vulnerable when confronting with the same earthquake. Specifically, Sichuan and Yunnan suffered losses of extra-large grade, Qinghai of large grade and Tibet, Xinjiang and Guangdong of moderate grade. These discoveries are helpful for earthquake mitigation and preparedness as well as earthquake loss evaluation in China.
[en] FePt (50 nm) and [FePt (x nm)/ZrO2 (0.5, 1, 2, 3 nm)]10 (x = 2, 5 nm) films were prepared by RF magnetron sputtering technique, then were annealed at 550 deg. C for 30 min. This work investigates the effect of ZrO2 layer thickness on structures and magnetic properties of FePt/ZrO2 multilayers. The X-ray diffraction results show that superlattice (0 0 1) peaks can be found in FePt (50 nm) and [FePt (5 nm)/ZrO2 (0.5, 1, 2, 3 nm)]10 films. Compared with single layer FePt film, superlattice (0 0 1) peaks of FePt/ZrO2 multilayers are wider and weaker, which indicates that introducing ZrO2 is advantageous to hinder the growth of FePt grains. The coercivities, grain size and intergrain interactions of FePt/ZrO2 films are decreased when ZrO2 layer thickness is increased. And grain volume (V grain) is almost identical to activation volume (V *) for added-ZrO2 films. Thus, the FePt/ZrO2 films with the appropriate coercivities, the small size of grains, and the weak intergrain interactions are obtained
[en] A series of Zn1-xCoxO thin films with the atomic fraction, x, in the range of 0.03-0.10 were deposited on glass substrates at room temperature by magnetron co-sputtering technique and subsequently coupled with the post-annealing treatment for half hour at different temperatures (350 deg. C and 500 deg. C) under vacuum. A systematic study was done on the structural, optical and magnetic properties of Zn1-xCoxO thin films as a function of Co concentration and annealing temperature. X-ray diffraction and UV-vis spectroscopy results indicated that there are not any secondary phases and Co2+ substituted for Zn2+ of ZnO host. Magnetic hysteresis loops were observed at room temperature, indicating that both the as-deposited samples and the annealed ones exhibit the room temperature ferromagnetism. It was also found that the magnetic saturation moment per Co atom decreases with increasing Co concentration, while the post-annealing treatment can enhance the magnetic moment of the films effectively
[en] The formation of L10 FePt nanoparticles by annealing of FePt/C multilayer films was studied. After annealing at 550 deg. C for 30 min, the superlattice peaks (0 0 1) and (1 1 0) found in the X-ray diffraction pattern of the FePt/C films indicate that the face-centered cubic disordered phase has been partially transformed into the L10 phase. FePt/C thin films became magnetically hard with a coercivity in the range 1.8-9.2 kOe due to the high anisotropy energy associated with the L10 ordered phase. The coercivity of the films decreased rapidly with increasing C layer thickness. With increasing C content, the grain size and intergrain interaction of the FePt/C multilayer films decreased. The coercivity not only depends on the C content, but also on the structure of the FePt/C mutilayer. The [FePt 3 nm/C 3 nm]10 sample shows a small dipolar interaction
[en] We study electromagnetically induced absorption (EIA) and transparency (EIT) in an optical-rf two-photon coupling configuration. It is shown that the interference effect due to interacting dark resonances results in an EIA for a resonant two-photon coupling and this EIA is observed to evolve into an EIT when there is a detuning in the two-photon coupling