Ternary diffusion coefficients of diethanolamine and N-methyldiethanolamine in aqueous solutions containing diethanolamine and N-methyldiethanolamine

Ternary diffusion coefficients of diethanolamine (DEA) and N-methyldiethanolamine (MDEA) in aqueous solutions containing DEA and MDEA using the Taylor dispersion technique have been measured for temperatures (303.2, 313.2, and 323.2 K). The systems studied were aqueous solutions containing total amine concentrations of 2.5 and 4.0 kmol m⁻³, each having four different amine molar ratios. The density and viscosity of the blended amine solutions were also measured. The mutual diffusion coefficients of aqueous DEA and aqueous MDEA solutions were also reported. The main diffusion coefficients (D₁₁ and D₂₂) and the cross-diffusion coefficients (D₁₂ and D₂₁) were reported as function of temperature and concentration of alkanolamines. The limiting conditions for the main diffusion coefficients and the cross-diffusion coefficients were discussed at first, and a comparison between the ratios of the cross-diffusion coefficients to the main diffusion coefficients for DEA and MDEA was made. The dependence of the main diffusion coefficients on the viscosity of solutions was also investigated.     

Comparison of complexed species of Eu in alumina-bound and free polyacrylic acid: a spectroscopic study

The speciation of Eu complexed with polyacrylic acid (PAA) and alumina-bound PAA (PAA(ads)) was studied at pH 5 in 0.1 M NaClO(4). Structural parameters were obtained from (7)F(0) -->(5)D(0) excitation spectra measured by laser-induced fluorescence spectroscopy as well as from Eu L(III)-edge extended X-ray absorption fine structure (EXAFS) spectra. The coordination mode was also investigated by infrared spectroscopy. To elucidate the nature of the complexed species, Eu-acetate complexes were used as references. The spectroscopic techniques show that two carboxylate groups with 2-3 (EuPAA) and 4-5 (EuPAA(ads)) water molecules are coordinated to Eu in the first coordination sphere. For EuPAA(ads), the coordination between carboxylate groups and Eu appears to be bidendate. A similar coordination is probable for EuPAA but the EXAFS data indicate a slightly distorted coordination. The results show that the degree of freedom of carboxylate groups is not the same for free or adsorbed PAA. For PAA, the degree of freedom is constrained by the flexibility of the methylene chain. When PAA is adsorbed on alumina, the polymer chains cannot any more be treated as independent chains. One may rather assume formation of aggregates that form an organic layer at the mineral surface presenting a complex arrangement of carboxylate groups.     

Optimal two-dimensional interpolatory ternary subdivision schemes with two-ring stencils

For any interpolatory ternary subdivision scheme with two-ring stencils for a regular triangular or quadrilateral mesh, we show that the critical Hölder smoothness exponent of its basis function cannot exceed , where the critical Hölder smoothness exponent of a function is defined to be

On the other hand, for both regular triangular and quadrilateral meshes, we present several examples of interpolatory ternary subdivision schemes with two-ring stencils such that the critical Hölder smoothness exponents of their basis functions do achieve the optimal smoothness upper bound . Consequently, we obtain optimal smoothest interpolatory ternary subdivision schemes with two-ring stencils for the regular triangular and quadrilateral meshes. Our computation and analysis of optimal multidimensional subdivision schemes are based on the projection method and the -norm joint spectral radius.

     

Spectrophotometric Determination of Sparfloxacin in Pharmaceutical Preparations by Ternary Complex Formation with Pd(II) and Eosin

Abstract

A simple, sensitive, and direct spectrophotometric method has been developed for the assay of sparfloxacin in bulk and pharmaceutical preparations. The proposed method is based on the formation of ternary complex between an investigated drug, palladium(II) ion and eosin in the presence of methylcellulose as surfactant and acetate buffer of pH 4.2. Spectrophotometrically, under the optimum conditions, the ternary complex showed absorption maximum at 550 nm, with apparent molar absorptivity of 2.69×10⁴ l mol^?1 cm^?1, Sandell's sensitivity of 0.01458 µg ml^?1 and linearity in the concentration range 1.6–16 µg ml^?1. The composition of the ternary complex was studied by Job's method of continuous variation and the result indicated that the molar ratio of SPFX: Pd: eosin is 1∶1∶1. The optimum reaction conditions and other analytical parameters are evaluated. The proposed method was successfully applied for the determination of SPFX in its pharmaceutical product with mean percentage recoveries of 99.71%. The observed data has been subjected to statistical analysis, which revealed high accuracy and precision.     

Liquid–liquid phase diagrams of H2O + 2-butanol + potassium phosphate and H2O + 2-butanol + Na2CO3 systems at 298.15 K

The phase diagrams for the ternary systems H₂O?+?2-butanol?+?K₂HPO₄/KH₂PO₄ (pH?=?7) and H₂O?+?2-butanol?+?Na₂CO₃ at 298.15?K were determined. Experimental binodals and tie lines for these systems are presented. The experimental results were correlated using an improved regular solution theory. The agreement between the correlation and experimental data is good.     

Densities and Viscosities of the Ternary Mixture (Benzene + 1-Propanol + Ethyl Acetate) at 298.15 K

Abstract

Densities and viscosities of the ternary mixture (benzene + 1-propanol + ethyl acetate) and the corresponding binary mixtures (benzene + 1-propanol, benzene + ethyl acetate and 1-propanol + ethyl acetate) have been measured at the temperature 298.15 K. From these measurements excess volumes, V^E , excess viscosities, η^E, and excess Gibbs energies of activation for viscous flow, G*^E , have been determined. The equation of Redlich-Kister has been used for fitting the excess properties of binary mixtures. The excess properties of the ternary system were fitted to Cibulka's equation.     

First‐order Raman scattering of the MAX phases: Ti2AlN,Ti2AlC0.5N0.5, Ti2AlC, (Ti0.5V0.5)2AlC,V2AlC,Ti3AlC2, and Ti3GeC2

Here, we report, for the first time, on the Raman spectra of Ti₂AlN, Ti₂AlC_0.5N_0.5, (Ti_0.5V_0.5)₂AlC, Ti₃AlC₂, and Ti₃GeC₂ and compare the results with those of Ti₂AlC and V₂AlC reported previously. The first‐order mode peaks of the end members are narrower than those of their respective solid‐solution compounds. The Ti₃AlC₂ and Ti₃GeC₂ phases show, in addition to atomic displacements of the ‘M’ and ‘A’ atomic planes, modes that correspond with vibrations of the ‘X’ sublattice relative to itself. We also predict the Raman modes using density functional theory. The agreement between theory and experiment was found to be satisfactory. Copyright © 2011 John Wiley & Sons, Ltd.