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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] Structure, electronic state and energy of SinC- and SinC-2 (n=1-7) anions have been investigated using the density functional theory. Structural optimization and frequency analysis are performed at the level B3LYP/6-311G(d). The charged-induced structural changes in these anions have been discussed. The strong C-C bond is also favored over C-Si bonds in the SinC-m anions in comparison with corresponding neutral cluster. Among different SinC- and SinC-2 (n=1-7) anions, Si3C-, Si5C- and Si2C-2 are most stable. Their stability has a decreasing tendency with the increase in the size of these clusters
[en] The quality of sputtered-deposited SmCo/Cr films used for high-density magnetic recording media depends on several sputtering factors of the SmCo magnetic layer. The investigation into the optimal sputtering conditions needs a large number of experiments. The orthogonal design of experiments and the analysis of variance are considered effective methods, which not only minimize the number of experiments but also optimize the sputtering condition of the SmCo layer for high coercivity of SmCo/Cr films. Using the orthogonal design of experiments, the effects of four factors, such as target-substrate distance, DC power, sputtering pressure and sputtering time, were simultaneously investigated by only nine experiments. It is found that target-substrate distance, DC power and the sputtering pressure are very important factors for coercivity, while the effect of sputtering time is not obvious. In addition, the optimal condition of the SmCo layer was obtained. It can be proved that the results of our experiment are at the 95% level
[en] Co/ZnO:Al granular films were made on glass substrates by sequential magnetron sputter deposition of ultrathin Co layer and ZnO:Al layer at room temperature. The as-deposited films consist of superparamagnetic Co particles dispersed in ZnO:Al (~2% Al) semiconductor matrix. Distinguished magnetoresistance effect at room temperature was obtained in the as-deposited films, which obviously reduced after annealing due to the growth of Co particles. The size of important magnetic particles was analyzed by Langevin function for hysteresis loops and magnetoresistance curves at room temperature. It was found that small magnetic particle contribute to magnetoresistance behavior and large particles dominate the room temperature magnetism in Co/ZnO:Al granular films.
[en] Graphical abstract: - Highlights: • Large range tuned localized surface plasmon resonance of Ag nanoparticles films. • The noble metal Ag has the strongest localized surface plasmon resonance and low optical loss. Besides, it is the cheaper than other noble metal. • The nanoparticles films fabricated using physical methods have the stronger interaction with substrates than chemical methods, which are not easy exfoliation. - Abstract: Noble metal nanoparticles (NPs) have received enormous attention since it displays uniquely optical and electronic properties. In this work, we study localized surface plasmon resonances (LSPR) at different thicknesses and substrate temperatures of Ag NPs films grown by Laser Molecule Beam Epitaxy (LMBE). The LSPR wavelength can be largely tuned in the visible light range of 470 nm to 770 nm. The surface morphology is characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The average size of Ag NPs increased with the thickness increased which leading to the LSPR band broaden and wavelength red-shift. As the substrate temperature is increased from RT to 200 °C, the Ag NPs size distribution becomes homogeneous and particle shape changes from oblate spheroid to sphere, the LSPR band displays sharp, blue-shift and significantly symmetric. Obviously, the morphology of Ag NPs films is important for tuning absorption position. We obtain the cubic crystal structure of Ag NPs with a (1 1 1) main diffraction peak from the X-ray diffraction (XRD) spectra. The high resolution TEM (HR-TEM) and selected area electron diffraction (SAED) prove that Ag NPs is polycrystal structure. The Ag NPs films with large range absorption in visible light region can composite with semiconductor to apply in various optical or photoelectric devices.
[en] Objective: To explore the role of Color Doppler Flowing Imaging(CDFI) in assessing metastatic lymph node for nasopharyngeal carcinoma (NPC). Methods: Neck lymph node were detected by CDFI in 206 patients who received the initial course radiotherapy in our hospital. The characteristic of neck node, such as position, figure, number, size, its relation to surrounding soft tissue, the ratio of longitudinal diameter over trnsverses' (L/T) and blood flow resistance index (RI), were recorded detailedly. Fine needle aspiration biopsy was performed on some of patients under the guide of ultrasound. Results: The clinical N-stage was changed markedly after CDFI plus biopsy, with up-staging in 25 from N0 to N1 , 6 N0 to N2, 20 N1 to N2, 3 N1 to N3, 4 N2 to N3; and down-staging in 14 from N2 to N1, 7 from N3 to N2. The misdiagnosis rate of node involvement by palpation was 38.3% (79/206). The sizes of lymph node detected by palpation were larger than those by CDFI (P< 0.05). The accuracy was 88.9% (288/324) when the criteria of positive lymph node was set as L/T ratio < 2 and RI > 0.6, and the value would reached to 92.9% (182/196) and 95.5% (107/112) when such criteria combined with the diameter and growth behavior of lymph node. Conclusion: Color Doppler Flowing Imaging is useful in N-staging for nasopharyngeal carcinoma by providing more reliable evidence. (authors)
[en] Bisphenol-A (BPA), an endocrine disruptor, is found to influence development of brain and behaviors in rodents. The previous study indicated that perinatal exposure to BPA impaired learning-memory and inhibited N-methyl-D-aspartate receptor (NMDAR) subunits expressions in hippocampus during the postnatal development in rats; and in cultured hippocampal neurons, BPA rapidly promotes dynamic changes in dendritic morphology through estrogen receptor-mediated pathway by concomitant phosphorylation of NMDAR subunit NR2B. In the present study, we examined the rapid effect of BPA on passive avoidance memory and NMDAR in the developing hippocampus of Sprague-Dawley rats at the age of postnatal day 18. The results showed that BPA or estradiol benzoate (EB) rapidly extended the latency to step down from the platform 1 h after footshock and increased the phosphorylation levels of NR1, NR2B, and mitogen-activated extracellular signal-regulated kinase (ERK) in hippocampus within 1 h. While 24 h after BPA or EB treatment, the improved memory and the increased phosphorylation levels of NR1, NR2B, ERK disappeared. Furthermore, pre-treatment with an estrogen receptors (ERs) antagonist, ICI182,780, or an ERK-activating kinase inhibitor, U0126, significantly attenuated EB- or BPA-induced phosphorylations of NR1, NR2B, and ERK within 1 h. These data suggest that BPA rapidly enhanced short-term passive avoidance memory in the developing rats. A non-genomic effect via ERs may mediate the modulation of the phosphorylation of NMDAR subunits NR1 and NR2B through ERK signaling pathway. - Highlights: → BPA rapidly extended the latency to step down from platform 1 h after footshock. → BPA rapidly increased pNR1, pNR2B, and pERK in hippocampus within 1 h. → ERs antagonist or MEK inhibitor attenuated BPA-induced pNR1, pNR2B, and pERK.
[en] We performed first-principles density functional theory calculation to investigate the electronic structures and magnetic properties of Fe/NO2 co-doped graphene. First, our study shows that the Fe/NO2 co-doped graphene preserves the unique linear dispersion of the charge carriers. More importantly, NO2 co-doping is a much effective way to compensate the shifting of EF, which can facilitate the Fe adsorbed graphene systems to retain the unique properties of graphene. Second, magnetic exchange energy calculation finds that long-range ferromagnetic coupling exists between two n-p pairs and the coupling strength can be obviously improved after NO2 co-doping.
[en] Bisphenol-A (BPA) is known to be a potent endocrine disrupter. Evidence is emerging that estrogen exerts a rapid influence on hippocampal synaptic plasticity and the dendritic spine density, which requires activation of NMDA receptors. In the present study, we investigated the effects of BPA (ranging from 1 to 1000 nM), focusing on the rapid dynamic changes in dendritic filopodia and the expressions of estrogen receptor (ER) β and NMDA receptor, as well as the phosphorylation of NMDA receptor subunit NR2B in the cultured hippocampal neurons. A specific ER antagonist ICI 182,780 was used to examine the potential involvement of ERs. The results demonstrated that exposure to BPA (ranging from 10 to 1000 nM) for 30 min rapidly enhanced the motility and the density of dendritic filopodia in the cultured hippocampal neurons, as well as the phosphorylation of NR2B (pNR2B), though the expressions of NMDA receptor subunits NR1, NR2B, and ERβ were not changed. The antagonist of ERs completely inhibited the BPA-induced increases in the filopodial motility and the number of filopodia extending from dendrites. The increased pNR2B induced by BPA (100 nM) was also completely eliminated. Furthermore, BPA attenuated the effects of 17β-estradiol (17β-E2) on the dendritic filopodia outgrowth and the expression of pNR2B when BPA was co-treated with 17β-E2. The present results suggest that BPA, like 17β-E2, rapidly results in the enhanced motility and density of dendritic filopodia in the cultured hippocampal neurons with the concomitant activation of NMDA receptor subunit NR2B via an ER-mediated signaling pathway. Meanwhile, BPA suppressed the enhancement effects of 17β-E2 when it coexists with 17β-E2. These results provided important evidence suggesting the neurotoxicity of the low levels of BPA during the early postnatal development of the brain.