The solubility of veratric acid (3,4-dimethoxybenzoic acid, with measured melting point of 453.12 K by differential scanning calorimetry, DSC) in eight monosolvents, including ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, methyl acetate, ethyl acetate, and 2-butanone, and binary mixtures of ethanol + 1-butanol was determined at (278 to 323) K and atmospheric pressure using a dynamic method. The modified Apelblat equation and two local composition models (NRTL and UNIQUAC) were used to correlate the solubility of veratric acid in pure solvents. The modified Apelblat and the Jouyban–Acree model were used to correlate the solute solubility in binary mixtures. A combination of the Jouyban–Acree model and van’t Hoff equation was used to predict solubility data in the mixed solvents at different temperatures and gives a reasonable prediction. Each of the correlation equations selected gives a good description of the relationship of solubility and the temperature, and correlated data of the modified Apelblat equation show the best agreement with the experimental data, with the overall relative average deviations values of 0.61 % and 0.62 % in pure solvents and binary mixtures, respectively.

In our experiment, a dynamic method was taken to measure the solubilities of the 2,4-dimethoxybenzoic acid under atmospheric pressure (p = 0.1 MPa) in ethanol, npropanol, isopropanol, n-butanol, isobutanol, and ethyl acetate as well as in the isopropanol + ethyl acetate mixtures from (288.15 to 323.15) K. The experiment results have proved that the rising temperature leads to increased solubility of the 2,4-dimethoxybenzoic acid in all selected solvents. The changing model parameters in each selected solvent was recorded and calculated, respectively, during the experiments and the solid− liquid equilibrium data in pure and mixed solvents was correlated with a series equations, including the modified Apelblat equation, Wilson equation, UNIQUAC equation, and the Jouyban−Acree. During the study, the computational values were in good agreement with the experimental results according to the calculations based on all selected equations, however the modified Apelblat equation stood out to be the most suitable with the most accuracy. In addition, some thermodynamic parameters of the solution of 2,4-dimethoxybenzoic acid including dissolution enthalpy (ΔH sol ), entropy (ΔS sol ) and the Gibbs energy (ΔG sol ) were obtained via the van't Hoff analysis. The positive values ofΔH sol andΔG sol indicated that the dissolution process of dissolving 2,4-dimethoxybenzoic acid is endothermic.

Densities for binary mixtures of three alkanols (1,2-propanediol, 1,3-propanediol, and ethane-1,2-diol) with 1,4-butanediol over the whole composition range have been measured at temperatures from (293.15 to 328.15) K in 5 K intervals. From these data, the excess molar volumes (V E ) and their standard deviations σ(V E ) were calculated. The experimental results were fitted to the Redlich-Kister equation using a multiparametric nonlinear regression analysis.

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Subwavelength optical field confinement and low-loss propagation are of great significance for compact photonic integration. However, the field confinement capability of plasmonic devices is always accompanied by the inherent Ohmic loss. Although recent studies have shown that sodium (Na) exhibits lower loss than noble metals in the near-infrared band, the field confinement ability has not been adequately assessed. Meanwhile, the high chemical reactivity of Na should be regulated for practical application. Two dielectric-coated Na nanowires, consisting of cylindrical Na nanowires with one or two dielectric layers as claddings, are proposed and investigated in this paper. Based on finite element calculations, we thoroughly study the modal fields and low-loss propagation properties of dielectric-coated Na nanowires. The results demonstrate that Na exhibits lower loss and stronger field confinement than the typical plasmonic material silver. These findings indicate the performance of plasmonic devices can be considerably improved by employing the metal Na compared with devices using noble metals, which may promote the applications in subwavelength photonic devices.