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931.
A.C. Sun Y.C. Tsai Jen-Hwa Hsu P.C. Kuo H.L. Huang 《Journal of magnetism and magnetic materials》2008
(Fe48Pt52)100−x–(MgO)x films were used to examine the performance of a perpendicular percolated medium. Two underlayers, Pt(0 0 1)/Cr(0 0 2) and MgO(0 0 2), were used for comparison. The (Fe48Pt52)100−x–(MgO)x film with the MgO underlayer exhibits a strong preference to segregate at FePt grain boundaries. The microstructure with small closely packed MgO particles (2–4 nm) dispersed uniformly in the L10 FePt matrix was achieved in the Pt/Cr underlayered sample. Structural data reveal that the precipitate is crystallographically coherent with the surrounding L10 FePt phase and preserves good lattice alignment. Magnetic results indicate significant pinning behavior for those introduced non-magnetic columns with an enhanced coercivity of about 70%—much greater than that of the MgO underlayered samples. Percolated perpendicular medium can be realized in the FePt system and a Pt(0 0 1)/Cr(0 0 2) underlayer promotes the formation of pinning sites within the FePt grains. 相似文献
932.
The plasmon and distribution effects of collective localized surface plasmons between incident light and active layer of PtOx-type super resolution near-field structure (super-RENS) have been studied using finite-difference time-domain method. Four types of distribution of Pt nanoparticles, i.e., type A, B, C, and D in active layer are investigated. We find that type C and D in active layer can provide higher field intensity in a wider range of particle size when the particle sizes are varied, and the out-going filed emerging from the active layer exhibit smaller spot size than those of type A and B. Type B, C and D also provide the additional path longer than that of type A, and excite more evanescent field which located in the far edge of the bubble from the optical axis of the incident beam. Results show that the type C structure is the best choice in the view point of designing the PtOx-type super-RENS. This study provides new information to design a super-RENS with superior resolution as well as other applications in nano photonic devices. 相似文献
933.
Tim W.T. Tsai Yao-Hung Tseng Jerry C.C. Chan 《Journal of Physics and Chemistry of Solids》2008,69(11):2628-2633
A series of binary borosilicate glasses prepared by the sol-gel method are shown to be bioactive. Tetraethyl orthosilicate (TEOS) and trimethylborate (TMB) in acidic medium are used to prepare xB2O3·(1−x)SiO2 glass systems for x=0.045-0.167. The formation of a layer of apatite-like mineral on the glass surface becomes apparent after soaking in simulated body fluid for 48 h. We have measured the 11B-11B homonuclear second moments of the borosilicate glasses and inferred that no macroscopic phase separation occurred in our glasses. The 11B chemical shift data also show that the formation of clustered boroxol rings is negligible in our glass system. Although the bioactivity of our borosilicate glasses is less than that of CaO-SiO2 sol-gel glasses, these simple binary systems could be taken as reference glass systems for the search of new bioactive borosilicate glasses. 相似文献
934.
蔡树棠 《应用数学和力学(英文版)》1983,4(5):681-697
In this article, as the velocity gradient is taken as a constant value, we obtain the solutions of the equation of fluctuation
velocity after Fourier transform. When the mean velocity gradient is small, they represent the picture of eddies, of which
the homogeneous turbulence (both isotropic and nonisotropic) of the final period is composed. By using the eddies of these
types at different times, we may compose the steady turbulent field with the constant velocity gradient and this field may
represent the turbulent field in the central part of the channel flow or pipe flow approximately. Then we may obtain the double
velocity correlation function of this turbulent field, which involves both longitudinal correlation coefficient
and the transversal correlation coefficient
. We compare these theoretical coefficients with the experimental data of these coefficients at initial period and final period
of isotropic homogeneous turbulence. And then we obtain the relationship between the turbulent double velocity correlation
coefficient
and the mean velocity gradient. Finally, we get the expressions of the Reynolds stress and the eddy viscosity coefficient. 相似文献
935.
Lin et al. proposed a mediated semi-quantum key distribution protocol in 2019. This study shows that Lin et al.'s protocol has a security loophole that could mount to the collective attack to reveal some information about the secret key without being detected. To overcome this problem, an improved protocol is proposed and its security is proven. 相似文献
936.
Chao-Hsuan Chen Pei-Chen Hsu Shih-Wei Hsu Kun-Ting Hong Kai-Yuan Chen Jie-Long He Der-Yang Cho Yun-Chi Wang Wen-Shin Chang Da-Tian Bau Chia-Wen Tsai 《Molecules (Basel, Switzerland)》2022,27(13)
6-hydroxydopamine (6-OHDA) is used to induce oxidative damage in neuronal cells, which can serve as an experimental model of Parkinson’s disease (PD). Jujuboside A and B confer free radical scavenging effects but have never been examined for their neuroprotective effects, especially in PD; therefore, in this study, we aimed to investigate the feasibility of jujubosides as protectors of neurons against 6-OHDA and the underlying mechanisms. 6-OHDA-induced neurotoxicity in the human neuronal cell lines SH-SY5Y and SK-N-SH, was used to evaluate the protective effects of jujubosides. These findings indicated that jujuboside A and B were both capable of rescuing the 6-OHDA-induced loss of cell viability, activation of apoptosis, elevation of reactive oxygen species, and downregulation of the expression levels of superoxide dismutase, catalase, and glutathione peroxidase. In addition, jujuboside A and B can reverse a 6-OHDA-elevated Bax/Bcl-2 ratio, downregulate phosphorylated PI3K and AKT, and activate caspase-3, -7, and -9. These findings showed that jujubosides were capable of protecting both SH-SY5Y and SK-N-SH neuronal cells from 6-OHDA-induced toxicity via the rebalancing of the redox system, together with the resetting of the PI3K/AKT apoptotic signaling cascade. In conclusion, jujuboside may be a potential drug for PD prevention. 相似文献
937.
938.
Yu‐Heng Deng Jung‐Tsai Chen Chia‐Hao Chang Kuo‐Sung Liao Kuo‐Lun Tung William E. Price Yusuke Yamauchi Kevin C.‐W. Wu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(41):12985-12988
Despite much progress in the development of mixed matrix membranes (MMMs) for many advanced applications, the synthesis of MMMs without particle agglomeration or phase separation at high nanofiller loadings is still challenging. In this work, we synthesized nanoporous zeolitic imidazole framework (ZIF‐8) nanoparticles with a particle size of 60 nm and a pore size of 0.34 nm in water and directly added them into an aqueous solution of the organic polymer poly(vinyl alcohol) (PVA) without an intermediate drying process. This approach led to a high‐quality PVA/ZIF‐8 MMM with enhanced performance in ethanol dehydration by pervaporation. The permeability of this MMM is three times higher than that of pristine PVA, and the separation factor is nearly nine times larger than that of pristine PVA. The significantly improved separation performance was attributed to the increase in the fractional free volume in the membranes. 相似文献
939.
A highly diastereoselective Michael-alkylation/oxidation methodology has been developed for the synthesis of optically active α-hydroxy-1,5-diester subunits. Inverse stereochemistry at the C2′ position could be achieved by using a Michael acceptor equipped with a suitable group followed by a highly stereoselective protonation. This methodology has been applied to the enantioselective synthesis of the upper fragment of (+)-retusine. 相似文献
940.