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101.
Mohammad Ghaffari Mark Shannon H. Hui Ooi Kiang Tan Ahmad Irannejad 《Surface science》2012,606(5-6):670-677
In this report, SrTi(1 ? x)Fe(x)O(3 ? δ) photocatalyst powder was synthesized by a high temperature solid state reaction method. The morphology, crystalline structures of obtained samples, was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM), respectively. The electronic properties and local structure of the perovskite STFx (0 ≤ x ≤ 1) systems have been probed by extended X-ray absorption fine structure (EXAFS) spectroscopy. The effects of iron doping level x (x = 0–1) on the crystal structure and chemical state of the STFx have been investigated by X-ray photoelectron spectroscopy and the valence band edges for electronic band gaps were obtained for STFx by ultraviolet photoelectron spectroscopy (UPS). A single cubic perovskite phase of STFx oxide was successfully obtained at 1200 °C for 24 h by the solid state reaction method. The XPS results showed that the iron present in the STFx perovskite structure is composed of a mixture of Fe3+ and Fe4+ (SrTi(1 ? x)[Fe3+, Fe4+](x)O(3 ? δ)). When the content x of iron doping was increased, the amount of Fe3+ and Fe4+ increased significantly and the oxygen lattice decreased on the surface of STFx oxide. The UPS data has confirmed that with more substitution of iron, the position of the valence band decreased. 相似文献
102.
Aimed at geometric applications, we prove the homology cobordism invariance of the L2‐Betti numbers and L2‐signature defects associated to the class of amenable groups lying in Strebel's class D(R), which includes some interesting infinite/finite non‐torsion‐free groups. This result includes the only prior known condition, that Γ is a poly‐torsion‐free abelian group (or a finite p‐group). We define a new commutator series that refines Harvey's torsion‐free derived series of groups, using the localizations of groups and rings of Bousfield, Vogel, and Cohn. The series, called the local derived series, has versions for homology with arbitrary coefficients and satisfies functoriality and an injectivity theorem. We combine these two new tools to give some applications to distinct homology cobordism types within the same simple homotopy type in higher dimensions, to concordance of knots in three manifolds, and to spherical space forms in dimension 3. © 2012 Wiley Periodicals, Inc. 相似文献
103.
104.
An efficient asymmetric Mannich-type reaction of α-cyano α-sulfonyl carbanions has been achieved by exploiting the structural modularity and anion-recognition ability of chiral 1,2,3-triazolium ions. This protocol has proven to be applicable to a variety of N-Boc imines and cyanosulfones, affording β-amino α-cyanosulfones in excellent yields with high stereoselectivities. 相似文献
105.
Dong-Hwan KimJae Gyu Jang Hoa Thi LeJin Young Kim Choon Woo Lim Tae Woo Kim 《Tetrahedron letters》2012,53(43):5791-5795
The structural, physical, and biological properties of heptakis{6-(4-hydroxymethyl-1H-[1,2,3]triazol-1-yl)-6-deoxy}-β-cyclodextrin (HTβCD) were investigated by a variety of methods, including NMR, UV/vis, circular dichroism spectroscopy, computer modeling, turbidity testing, Ka measurements, and the MTT assay. The experimental results suggest that HTβCD is structurally well-defined, highly water-soluble, and has low cytotoxicity. These advantages of HTβCD versus β-CD indicate that β-cyclodextrin click clusters may function both as host molecules and as potential, alternative excipients to β-CD. 相似文献
106.
Choon Ki Ahn 《Nonlinear dynamics》2010,60(4):703-711
In this paper, we propose a new ℋ∞ synchronization strategy, called a fuzzy delayed output feedback ℋ∞ synchronization (FDOFHS) strategy, for chaotic systems in the presence of external disturbance. Based on Lyapunov–Krasovskii
theory, the T–S fuzzy model, and a delayed feedback control scheme, the FDOFHS controller can guarantee stable synchronization.
Furthermore, this controller reduces the effect of external disturbance to an ℋ∞ norm constraint. The proposed controller can be obtained by solving the linear matrix inequality (LMI) problem. A simulation
study is presented to demonstrate the validity of the proposed FDOFHS approach. 相似文献
107.
Choon Ki Ahn 《Nonlinear dynamics》2010,60(3):295-302
This paper proposes a new neural network ?∞ synchronization (NNHS) scheme for unknown chaotic systems. In the proposed framework, a dynamic neural network is constructed as an alternative to approximate the chaotic system. Based on this neural network and linear matrix inequality (LMI) formulation, the NNHS controller and the learning law are presented to reduce the effect of disturbance to an ?∞ norm constraint. It is shown that finding the NNHS controller and the learning law can be transformed into the LMI problem and solved using the convex optimization method. A numerical example is presented to demonstrate the validity of the proposed NNHS scheme. 相似文献
108.
Choon Ki Ahn 《Nonlinear dynamics》2010,61(3):483-489
This paper proposes a new delay-dependent state estimator for Takagi–Sugeno (T-S) fuzzy delayed Hopfield neural networks. By employing a suitable Lyapunov–Krasovskii functional, a delay-dependent criterion is established to estimate the neuron states through available output measurements such that the dynamics of the estimation error is asymptotically stable. It is shown that the design of the proposed state estimator for such neural networks can be achieved by solving a linear matrix inequality (LMI), which can be easily facilitated by using some standard numerical packages. An illustrative example is given to demonstrate the effectiveness of the proposed state estimator. 相似文献
109.
Choon Kyung Cho Bang Soo Ha Sungkwon Kang 《Journal of Applied Mathematics and Computing》2001,8(2):325-336
Spatial distribution of groundwater contaminant concentration has special characteristics such as approximate symmetric profile, for example, in the transversal direction to groundwater flow direction, a certain ratio in directional propagation distances, etc. To obtain a geophysically appropriate semivariogram which is a key factor in estimation of groundwater contaminant concentration at desired locations, these special characteristics should be considered. Specifically, the concepts of symmetry and ratio are considered in this paper. By applying these two concepts, significant improvement of semivariograms, estimation variances, and final estimation results compared with the ones by conventional approaches which usually do not account for symmetry and ratio are shown using field experimental data. 相似文献
110.
In vitro evaluation of secoiridoid glucosides from the fruits of Ligustrum lucidum as antiviral agents. 总被引:1,自引:0,他引:1
S C Ma Z D He X L Deng P P But V E Ooi H X Xu S H Lee S F Lee 《Chemical & pharmaceutical bulletin》2001,49(11):1471-1473
Six secoiridoid glucosides, lucidumoside C (1), oleoside dimethylester (2), neonuezhenide (3), oleuropein (4), ligustroside (5) and lucidumoside A (6), isolated from the fruits of Ligustrum lucidum (Oleaceae), were examined in vitro for their activities against four strains of pathogenic viruses, namely herpes simplex type I virus (HSV-1), influenza type A virus (Flu A), respiratory syncytial virus (RSV) and parainfluenza type 3 virus (Para 3). Antiviral activities were evaluated by the cytopathic effect (CPE) inhibitory assay. The purpose was to check if the antioxidative potency of these glucosides correlated with their antiviral potency. Results showed that none of the glucosides had any significant activity against HSV-1 and Flu A. Oleuropein, however, showed significant antiviral activities against RSV and Para 3 with IC50 value of 23.4 and 11.7 microg/ml, respectively. Lucidumoside C, oleoside dimethylester and ligustroside showed potent or moderate antiviral activities against Para 3 with IC50 values of 15.6-20.8 microg/ml. These results also documented that the anti-oxidative potency of these secoiriodoid glucosides was not directly related to their antiviral effects. 相似文献