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91.
Shahrokh Hosseini-Hashemi Mohammad Fadaee Hossein Rokni Damavandi Taher 《Applied Mathematical Modelling》2011
In this paper, exact closed-form solutions in explicit forms are presented for transverse vibration analysis of rectangular thick plates having two opposite edges hard simply supported (i.e., Lévy-type rectangular plates) based on the Reddy’s third-order shear deformation plate theory. Two other edges may be restrained by different combinations of free, soft simply supported, hard simply supported or clamped boundary conditions. Hamilton’s principle is used to derive the equations of motion and natural boundary conditions of the plate. Several comparison studies with analytical and numerical techniques reported in literature are carried out to demonstrate accuracy of the present new formulation. Comprehensive benchmark results for natural frequencies of rectangular plates with different combinations of boundary conditions are tabulated in dimensionless form for various values of aspect ratios and thickness to length ratios. A set of three-dimensional (3-D) vibration mode shapes along with their corresponding contour plots are plotted by using exact transverse displacements of Lévy-type rectangular Reddy plates. Due to the inherent features of the present exact closed-form solution, the present findings will be a useful benchmark for evaluating the accuracy of other analytical and numerical methods, which will be developed by researchers in the future. 相似文献
92.
The results of the innovative study on a new stationary phase with high efficiency based on ZnO nano and micro rod coating on fused silica are reported in this paper. ZnO nanorods with a diameter in the range of 70–300 nm and the length of about 500 nm, have been grown on fused silica fibers using a hydrothermal process. The extraction properties of the fiber were investigated using headspace solid-phase microextraction (HS-SPME) mode coupled with gas chromatography–mass spectrometry detection (GC–MS) for 1,4-dichloro-nitrobenzene, biphenyl and acenaphthene. The calibration curves were linear up to 102–107 ng L−1 (R2 > 0.995) with detection limits of 10−3 ng L−1 for biphenyl and acenaphthene and 10 ng L−1 for 1,4-dichloro-nitrobenzene. The RSD for single fiber and fiber-to-fiber were less than 7.0 and 11.5%, respectively. The high stability of the ZnO coating is proved at relatively high temperatures (up to 300 °C) with a high extraction capacity and long lifespan (more than 100 times). Promising recoveries (91–102%) were obtained in environmental water samples analysis by applying the proposed technique. 相似文献
93.
A novel and tandem synthesis of highly functionalized tetrahydroindeno[1,2‐d]imidazole is described. A one‐pot reaction between a primary amine, an aryl isothiocyanate, and ninhydrin leads to highly substituted indeno[1,2‐d]imidazoles under solvent‐free conditions in excellent yields (Scheme). Their structures were corroborated spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS) and by elemental analyses. 相似文献
94.
Ahmadi F Alizadeh AA Shahabadi N Rahimi-Nasrabadi M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1466-1474
In this work a complex of Al3+ with curcumin ([Al(curcumin) (EtOH)2](NO3)2) was synthesized and characterized by UV-vis, FT-IR, elemental analysis and spectrophotometric titration techniques. The mole ratio plot revealed a 1:1 complex between Al3+ and curcumin in solution. For binding studies of this complex to calf thymus-DNA various methods such as: UV-vis, fluorescence, circular dichroism (CD), FT-IR spectroscopy and cyclic voltammetry were used. The intrinsic binding constant of ACC with DNA at 25°C was calculated by UV-vis and cyclic voltammetry as 2.1×10(4) and 2.6×10(4), respectively. The thermodynamic studies showed that the reaction is enthalpy and entropy favored. The CD results showed that only the Δ-ACC interacts with DNA and the Δ-ACC form has not any tendency to interact with DNA, also the pure curcumin has not any stereoselective interaction with CT-DNA. Fluorimetric studies showed that fluorescence enhancement was initiated by a static process in the ground state. The cyclic voltammetry showed that ACC interact with DNA with a binding site size of 2. From the FT-IR we concluded that the Δ-ACC interacts with DNA via partial electrostatic and minor groove binding. In comparison with previous works it was concluded that curcumin significantly reduced the affinity of Al3+ to the DNA. 相似文献
95.
Czechoslovak Mathematical Journal - Let $${{\cal D}_{\lambda ,\mu }}$$ be the space of linear differential operators on weighted densities from $${{\cal F}_\lambda }$$ to $${{\cal F}_\mu }$$ as... 相似文献
96.
S. El‐Taher 《International journal of quantum chemistry》2005,102(2):178-188
Ab initio and Density Functional Theory (DFT) calculations were performed to determine the equilibrium geometries, charge distributions, spin density distributions, dipole moments, electron affinities (EAs), and C–O bond dissociation energies (BDEs) of CH2ClO2? CHCl2O2?, CCl3O2?, CF2ClO2?, CFCl2O2?, and CHFClO2? peroxyl radicals. The C–H BDEs of the parent methanes were calculated using the same levels of theories. Both MP2(full) and B3LYP methods, using the 6‐31G(d,p) basis set, were found to be capable of accurately predicting the geometries of peroxyl radicals. The B3LYP/6‐31G(d,p) method was found to be comparable to high ab initio levels in predicting C–O BDEs of studied peroxyl radicals and C–H BDEs of the parent alkanes. The progressive chlorine substitution of hydrogen atoms in methyl peroxyl radicals results in an increase (decrease) of the spin density on the terminal (inner) oxygen, a decrease in dipole moments, and an increase in electron affinities. The substitution of fluorine by chlorine in the series CF3O2? – CCl3O2? was found to lengthen (destabilize) the C–O bonds. Both C–O BDEs and EAs of peroxyl radicals (RO2?) were found to correlate well with Taft σ* substituent constants for the R groups. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
97.
In this work, we intend to study the thermal
properties of the soaked steels like XC48 and their evolution according to
the heating temperature and for different soaking media, using the “Mirage
effect” method which permits the simultaneous determination of thermal
conductivity and diffusivity. We have observed a discontinuity of thermal
conductivity and diffusivity at the temperature of the ferro-paramagnetic
transition. 相似文献
98.
Muhammad Taher Abuelma'atti 《International Journal of Infrared and Millimeter Waves》1995,16(1):217-229
Analytical expressions are obtained for predicting the harmonic and intermodulation performance of R-LED series networks. These expressions are in terms of the ordinary Bessel functions with arguments depenedent on the modulation index. 相似文献
99.
Kell AJ Alizadeh A Yang L Workentin MS 《Langmuir : the ACS journal of surfaces and colloids》2005,21(21):9741-9746
Acyl and alkyl radicals generated photochemically in a solution containing monolayer-protected gold nanoparticles are shown to efficiently liberate the alkylthiolate ligands into the solution as the thioacetyl or alkyl sulfide, respectively. This radical-induced reaction initiates a coalescence of the gold cores to facilitate an increase in core size. The photoinitiated radical reaction also liberates monolayers from two-dimensional gold surfaces. 相似文献
100.
Saieed Akbari Hadi Alizadeh Tınaz Ekim Didem Gözüpek Mordechai Shalom 《Discrete Mathematics》2018,341(10):2859-2871
A graph is equimatchable if all of its maximal matchings have the same size. A graph is claw-free if it does not have a claw as an induced subgraph. In this paper, we provide the first characterization of claw-free equimatchable graphs by identifying the equimatchable claw-free graph families. This characterization implies an efficient recognition algorithm. 相似文献