Shape effect on weakly nonlinear elliptical composites

The electric field responses of two types of weakly nonlinear dielectric composites consisting of elliptic cylindrical inclusions, one with identical shape and the another with distributed shapes, randomly embedded in the linear host media in the dilute limit are investigated. The dielectric property of the inclusions is that the relation between the displacement (D) and electric (E) fields obey the form D = ?E + χ∣E∣^βE where β is a nonlinear integer exponent and ? ? χ∣E∣^β. By using the decoupling approximation, the effective nonlinear susceptibility (χ_e) is determined and analyzed for varying the aspect ratios and the shape distribution parameters for the composites with identical and distributed inclusion shapes, respectively. In addition, the exact analytic result of χ_e for the elliptical composites with distributed inclusion shapes for the case of β = 2 is derived in this article.     

Influence of polyacrylic acid (PAA)/Na2HPO4 mixture on biphasic calcium phosphate cement: Enhancing strength and cell viability

This study has investigated the effect of combination of new liquid phase mixture of disodium hydrogen phosphate (Na₂HPO₄) and polyacrylic acid (PAA) on the compressive strength, setting time, bioactivity, and cytotoxicity of biphasic calcium phosphate cement. The PAA was known as one of water-soluble and biocompatible polymers to improve the mechanical performances of the bone cement, but it usually inhibits the phase conversion to hydroxyapatite after the cement has already set. The aim of this work was to evaluate the incorporation of the mixture of PAA and Na₂HPO₄ into biphasic cement. We have found the crucial concentration for adding PAA/Na₂HPO₄ at 30:70 v/v% to enhance the mechanical strength, cell viability, and maintain bioactivity. The phase composition and crosslinking reaction between PAA and alpha-tricalcium phosphate (α-TCP) powder were detected by XRD and FTIR techniques. The beta-tricalcium phosphate (β-TCP) was added in the formula to achieve the biphasic cement, which composed of β-TCP and apatite/calcium deficient-hydroxyapatite (CD-HA) in the final product. The biphasic granule commercial product was used as comparison in the cell viability test. This work had been confirmed that the cement was a nontoxic material. Therefore, our results suggest that the PAA/Na₂HPO₄ could be beneficial for further clinical applications.     

Structural evaluation of ZnO substitution for CaO in glass ionomer cement synthesized by sol-gel method and their properties

Journal of Materials Science - The substitution of ZnO for CaO site and the limitation of ZnO addition in the sol-gel ionomer glass composition at different calcination temperatures were evaluated...