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91.
The influence of erbium (Er3+) ion concentration on the infrared emission at 1.5 μm in TeO2-WO3 and TeO2-CdO-WO3 glasses was studied. The samples were prepared by conventional melt quenching method. The optical properties were studied by measuring the absorption and luminescence spectra at room temperature. The Judd-Ofelt parameters (Ωt), transition probabilities, branching ratios of various transitions and their radiative lifetimes were calculated from the optical absorption spectra. Absorption and emission cross-section spectra and the Stark Levels splitting for the 4I13/2 to 4I15/2 transition of Er3+ centered at 1.5 μm were determined. 相似文献
92.
Aurones, derivatives of 2-benylidenebenzofuran-3(2H)-one, are natural products that serve as plant pigments. There have been reports that some of these substances fluoresce,
but little information about their optical properties is in the literature. In this report, series of aurone derivatives were
synthesized as possible fluorescent probes that can be excited by visible light. We found that an amine substituent shifted
the lowest energy absorption band from the near-UV to the visible region of the electromagnetic spectrum. Four amine-substituted
aurone derivatives were synthesized to explore the effect of this substituent on the absorption and emission properties of
the aurone chromophore. The emission maxima and intensities of the molecules are strongly dependent on the nature of the substituent
and the solvent polarity. Overall, the emission intensity increases and the maximum wavelength decreases in less polar solvents;
thus, the aurones may be useful probes for hydrophobic sites on biological molecules. A limited investigation with model protein,
nucleic acid and fixed cells supports this idea. It is known that the sulfur analog of aurone can undergo photo-induced E/Z isomerization. This possibility was investigated for one of the aminoaurones, which was observed to reversible photoisomerize.
The two isomers have similar absorption spectra, but the emission properties are distinct. We conclude that appropriately
substituted aurones are potentially useful as biological probes and photoswitches. 相似文献
93.
Ozlem Erdas Cenk A. Andac A. Selen Gurkan‐Alp Ferda Nur Alpaslan Erdem Buyukbingol 《Journal of Chemometrics》2013,27(6):155-164
Analyses of known protein–ligand interactions play an important role in designing novel and efficient drugs, contributing to drug discovery and development. Recently, machine learning methods have proven useful in the design of novel drugs, which utilize intelligent techniques to predict the outcome of unknown protein–ligand interactions by learning from the physical and geometrical properties of known protein–ligand interactions. The aim of this study is to work through a specific example of a novel computational method, namely compressed images for affinity prediction (CIFAP), in which binding affinities for structurally related ligands in complexes with human checkpoint kinase 1 (CHK1) are predicted. The CIFAP algorithm presented here relates published pIC 50 values of 57 compounds, derived from a thienopyridine pharmacophore, in complexes with CHK1 to their two‐dimensional (2D) electrostatic potential images compressed in orthogonal dimensions. Patterns obtained from the 2D images are then used as inputs in regression and learning algorithms such as support vector regression (SVR) and adaptive neuro‐fuzzy inference system (ANFIS) methods to validate the experimental pIC 50 values. This study revealed that the 2D image pixels in the vicinity of bound ligand surfaces provide more relevant information to make correlations with the empirical pIC 50 values. As compared with ANFIS, SVR gave rise to the lowest root mean square errors and the greatest correlations, suggesting that SVR could be a plausible choice of machine learning methods in predicting binding affinities by CIFAP. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
94.
Guleli Muge Erdem Safiye S. Ocal Nuket Erden Ihsan Sari Ozlem 《Research on Chemical Intermediates》2019,45(4):2119-2134
Research on Chemical Intermediates - An efficient and general method for the synthesis of substituted 3,4-dimethylisoxazolo[5,4-b]pyridine-5-carboxamide and benzo[b][1,8]naphthyridine-3-carboxamide... 相似文献
95.
Yakan Hasan Cakmak Sukriye Kutuk Halil Yenigun Semiha Ozen Tevfik 《Research on Chemical Intermediates》2020,46(5):2767-2787
Research on Chemical Intermediates - We performed a series of novel benzamide compounds which were synthesized starting from 2,3-dimethoxybenzoic acid or 3-acetoxy-2-methylbenzoic acid and amine... 相似文献
96.
The flow field resulting from the interaction between a planar incident shock in a solid and an embedded ellipsoidal gas cavity
is examined computationally. The study is motivated by the need for improved understanding of the role of embedded cavities
in the initiation of reaction in a heterogeneous explosive following the application of a shock. The system is modeled as
a compressible multi-fluid flow with a sufficiently strong shock in the solid. A high-resolution, Godunov-type capturing scheme
is employed to solve the governing equations numerically. The calculations are performed in parallel and use adaptive mesh
refinement to obtain well-resolved solutions. The goal is to identify regions in which the shock-cavity interaction results
in pressures that are substantially higher than the post-shock pressure that existed prior to the beginning of the interaction.
Also of interest are the ways in which the magnitude of the elevated pressure, the extent and location of the regions where
it develops, and the mechanisms that underlie such a development are influenced by the strength of the shock and the geometry
of the cavity. 相似文献
97.
Principles of hierarchical meso- and macropore architectures by liquid crystalline and polymer colloid templating 总被引:1,自引:0,他引:1
Sel O Kuang D Thommes M Smarsly B 《Langmuir : the ACS journal of surfaces and colloids》2006,22(5):2311-2322
The generation of porous silica with hierarchically organized bimodal mesoporosity of adjustable size and well-defined shape was investigated by using surfactant mixtures and the nanocasting procedure (liquid crystalline templating). A systematic study of combinations of various block copolymers (Pluronics F127, KLE (poly(omega-hydroxypoly(ethylene-co-butylene)-co-poly(ethylene oxide))) and SE (PS-co-PEO)) with smaller surfactants (Pluronics P123, C16mimCl, and CTAB) revealed that hierarchical bimodal mesopore architectures could only be obtained by the usage of block copolymers with a strong hydrophilic-hydrophobic contrast, such as KLE and SE, giving rise to pores between 6 and 22 nm. Furthermore, the ionic liquid (IL) C16mimCl appeared to have advantageous templating properties, resulting in 2-3-nm pores being located between the block copolymer mesopores, whereas phase separation was observed for Pluronics and CTAB as small templates. Thereby, the study provided also general insights into the mixing and co-self-assembly behavior of block copolymers and ionic surfactants in water and confirmed the special templating properties of ILs, as recently proposed. In addition to the bimodal mesoporosity, additional tunable macroporosity was created by the presence of poly(styrene) or poly(methyl methacrylate) spheres, leading to well-defined trimodal hierarchical pore architectures with the small pores being located in the walls of the respective larger pores. As a major improvement, due to the pore hierarchy, these large-pore materials showed relatively large surface areas and pore volumes, and the size of densely packed macropores could even be decreased down to 90 nm. The materials were characterized by electron microscopy, small-angle X-ray scattering, and nitrogen sorption using a proper NLDFT (nonlocal density functional theory) approach for calculations of the pore size distribution in the entire range of micro- and mesopores. 相似文献
98.
In the numerical solution of some boundary value problems by the finite element method (FEM), the unbounded domain must be truncated by an artificial absorbing boundary or layer to have a bounded computational domain. The perfectly matched layer (PML) approach is based on the truncation of the computational domain by a reflectionless artificial layer which absorbs outgoing waves regardless of their frequency and angle of incidence. In this paper, we present the near-field numerical performance analysis of our new PML approach, which we call as locally-conformal PML, using Monte Carlo simulations. The locally-conformal PML method is an easily implementable conformal PML implementation, to the problem of mesh truncation in the FEM. The most distinguished feature of the method is its simplicity and flexibility to design conformal PMLs over challenging geometries, especially those with curvature discontinuities, in a straightforward way without using artificial absorbers. The method is based on a special complex coordinate transformation which is ‘locally-defined’ for each point inside the PML region. The method can be implemented in an existing FEM software by just replacing the nodal coordinates inside the PML region by their complex counterparts obtained via complex coordinate transformation. We first introduce the analytical derivation of the locally-conformal PML method for the FEM solution of the two-dimensional scalar Helmholtz equation arising in the mathematical modeling of various steady-state (or, time-harmonic) wave phenomena. Then, we carry out its numerical performance analysis by means of some Monte Carlo simulations which consider both the problem of constructing the two-dimensional Green’s function, and some specific cases of electromagnetic scattering. 相似文献
99.
Modeling the information of social contagion processes has recently attracted a substantial amount of interest from researchers due to its wide applicability in network science, multi-agent-systems, information science, and marketing. Unlike in biological spreading, the existence of a reinforcement effect in social contagion necessitates considering the complexity of individuals in the systems. Although many studies acknowledged the heterogeneity of the individuals in their adoption of information, there are no studies that take into account the individuals’ uncertainty during their adoption decision-making. This resulted in less than optimal modeling of social contagion dynamics in the existence of phase transition in the final adoption size versus transmission probability. We employed the Inverse Born Problem (IBP) to represent probabilistic entities as complex probability amplitudes in edge-based compartmental theory, and demonstrated that our novel approach performs better in the prediction of social contagion dynamics through extensive simulations on random regular networks. 相似文献
100.
Let H be a Hilbert space with inner product (⋅,⋅) and ‖⋅‖ norm, and let K be weakly compact a subset of H. Let be nonlinear mapping and be a nonlinear bounded mapping. In this paper, we define the I-asymptotically quasi-nonexpansive mapping in Hilbert space. If T is an I-asymptotically quasi-nonexpansive mapping, then we prove that , for u∈K as n→∞, is weakly almost convergent to its asymptotic center. 相似文献