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181.
In this study, the effect of Zn-dopant on the physical properties and microstructure of hydroxyapatite (HAP) bioceramics was
investigated. The average crystallite size, phase composition and degree of crystallization of the pure hydroxyapatite and
Zn-doped hydroxyapatite bioceramic samples prepared by sol–gel method were determined by X-ray diffraction method. It was
seen that all the bioceramic samples were composed of the nanoparticles (29–46 nm). Fourier transform infrared spectroscopy
was used to determine the functional groups in the samples. The dielectric properties of the bioceramics were investigated
by dielectric impedance spectroscopy method, and the surface morphologies of them were analyzed using scanning electron microscopy
technique. When the densities of the samples were measured by Archimedes method, it was seen that the densities of the samples
increased with the increase of the molar ratio of Zn. The crystallization degree for all the samples dramatically decreased
with the increasing content of the Zn dopant. With the increase of Zn to HAP, a change was observed in the degree of the crystallization,
phase compositions, dielectric properties and microstructures of the samples. 相似文献
182.
α,α-Dibromo-2-methoxyacetophenone reacts, under mild reaction conditions, with C-, N- and O-nucleophiles via a bromophilic substitution/protonation/carbophilic substitution cascade process to afford α-monosubstituted-2-methoxyacetophenones in moderate to good yield. The only exception from this reaction pathway is the reaction with the anion derived from malononitrile in which 2-aroyl-1,1,3,3-tetracyanopropene is obtained. 相似文献
183.
We consider the following nonlinear viscoelastic equation together with Dirichlet-boundary conditions, in a bounded domain Ω and ρ > 0. We prove an exponential decay result for a class of relaxation functions. Our result is established without imposing the usual relation between g and its derivative (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
184.
Nasser-eddine Tatar 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2009,60(4):640-650
In this paper we consider a problem which arises in viscoelasticity. We prove exponential decay of solutions for the problem
with a memory term involving a kernel which is singular at zero. This is established by introducing an appropriate Lyapunov
type functional and using the energy method. This work extends earlier results.
相似文献
185.
A blow up result for a fractionally damped wave equation 总被引:3,自引:0,他引:3
In this paper we prove a blow up result for solutions of the wave equation with damping of fractional order and in presence
of a polynomial source. This result improves a previous result in [5]. There we showed that the classical energy is unbounded
provided that the initial data are large enough. 相似文献