Speed of Sound, Isentropic Compressibilities, and Excess Molar Volumes of Binary Mixtures Containing p-Dioxane

The speed of sound u in and densities of eight binary mixtures of p-dioxane (p-C₄H₈O₂) with methylcyclohexane (c-C₆H₁₁CH₃), 1-chlorohexane (C₆H₁₃C1), 1-bromohexane (C₆H₁₃Br), p-xylene [C₆H₄(CH₃)₂], propylbenzene (C₆H₅C₃H₇), methyl acetate CH₃COOCH₃), butyl acetate (CH₃COOC₄H₉), and amyl acetate (CH₃COOC₅H₁₁) were measured over the whole composition range at 30°C. Isentropic compressibilities (K _S), Rao's molar sound functions (R), excess molar volumes (V ^E), excess isentropic compressibilities (K _S ^E ) together with relative change in volume V/₁₂ values, have been obtained for all measured mole fractions. The excess partial molar volume (V₁-V ₁ ⁰ ) of p-dioxane in different solvents have also been estimated. The experimental results have been analyzed in terms of the Prigogine–Flory–Patterson theory of solutions.     

Studies of viscosities of dilute solutions of alkylamines in non-electrolyte solvents: III. Alkylamines in butanols at 303.15 K

Freezing in winter cereals is a complex phenomenon that can affect various plant tissues differently. To better understand how freezing affects specific tissue in the over wintering organ (crown) of winter cereal crops, non-acclimated oats (Avena sativa L.) were gradually frozen to ?3 °C and tissue damage during recovery was compared to plants that had been supercooled to ?3 °C and then frozen suddenly. Percentage of total water frozen, was the same whether crowns were frozen suddenly or gradually although the rate of freezing was considerably different. For example, all available water froze within 3 h in suddenly frozen crowns but it took more than 15 h for all available water to freeze in gradually frozen crowns. When plants were suddenly frozen, cells in the apical meristem were disrupted and apparently killed. In these plants re-growth was limited or non-existent. In contrast, the apical region of plants that were slowly frozen appeared undamaged but extensive vessel plugging was observed in cells of the lower crown, possibly from accumulation of phenolics or from microbial proliferation. These histological observations along with the calorimetric analysis suggested that the apical region was killed by intracellular freezing when frozen suddenly while the crown core was damaged by a process, which either induced production of putative phenolic compounds by the plant and/or permitted what appeared to be microbial proliferation in metaxylem vessels.     

Volumetric and Transport Properties of Ternary Mixtures Containing 1-Butanol or 1-Pentanol,Triethylamine and Cyclohexane at 303.15 K: Experimental Data,Correlation and Prediction by the ERAS Model

The excess molar volumes, V _m^E, viscosity deviations, Δη, and excess Gibbs energies of activation, ΔG ^*E, of viscous flow have been investigated from density and viscosity measurements for two ternary mixtures, 1-butanol + triethylamine + cyclohexane and 1-pentanol + triethylamine + cyclohexane, and corresponding binaries at 303.15 K and atmospheric pressure over the entire range of composition. The empirical equations due to Redlich-Kister, Kohler, Rastogi et al., Jacob-Fitzner, Tsao-Smith, Lark et al., Heric-Brewer, and Singh et al. have been employed to correlate V _m^E, Δη and ΔG ^*E of the ternary mixtures with their corresponding binary parameters. The results are discussed in terms of the molecular interactions between the components of the mixture. Further, the Extended Real Associated Solution, ERAS, model has been applied to V _m^E for the present binary and ternary mixtures, and the results are compared with experimental data.     

Viscosity and excess molar volume of binary mixtures of methanol with n-butylamine and di-n-butylamine at 303.15, 313.15 and 323.15 K. Characterization in terms of ERAS model

The excess molar volume V_m^E, viscosity deviation Δη, and excess Gibbs energy of activation ΔG^?E of viscous flow have been investigated from the density ρ and viscosity η measurements of binary mixtures of methanol with n-butylamine and di-n-butylamine over the entire range of mole fractions at 303.15, 313.15, and 323.15 K. The systems studied exhibit very strong cross association through strong O–H…N bonding between –OH and –NH– groups. As a consequence of this strong intermolecular association, both the systems have very large negative V_m^E and positive Δη and ΔG^?E over entire range of composition and at all the temperatures of investigation. V_m^E of the studied mixtures is consistently described by the ERAS model. The values of cross association constants K_AB illustrate that cross-associates are more pronounced in primary amine mixtures than that in secondary amine.     

Studies of partial molar volumes of alkylamine in non-electrolyte solvents II. Alkyl amines in chloroalkanes at 303.15 and 313.15 K

Apparent molar volumes V_?,B of n-propylamine, n-butylamine, di-n-propylamine, di-n-butylamine, tri-n-propylamine, and tri-n-butylamine in tetrachloromethane and trichloromethane at 303.15 and 313.15 K have been calculated from the densities ρ determined with high precision vibrating tube densimeter. From these data limiting partial molar volumes V¯_B^∞ and limiting excess partial molar volumes V¯_B^E,∞ were estimated. The results are analysed and interpreted in terms of solute–solvent interactions and structural effects of the molecules. An attempt to find a measure of the contribution of the specific interactions to the partial molar volumes of primary, secondary and tertiary amines in tetra- and tri-chloromethane was made using Terasawa model, scaled particle theory (SPT) and hard sphere theory (HST).     

Speed of sound and isentropic compressibilities of nonelectrolyte liquid mixtures. I. Binary mixtures containingp-dioxane

The speed of sound was measured for mixtures of p-dioxane with cyclohexane, n-hexane, benzene, toluene, carbon tetrachloride, chloroform, 1,1,2,2-tetrachloroethane, pentachloroethane and ethyl acetate over the whole mole fraction range at 30°C. These data were combined with densities and molar volumes to obtain isentropic compressibilities and Rao's molar sound functions. Excess isentropic compressibilities and excess speeds of sound have also been calculated. The behavior of the present mixtures is discussed in terms of possible molecular interactions and the Prigogine-Flory-Patterson theory of liquid mixtures.     

Investigation on major,minor and trace elements in some medicinal plants using Particle Induced X-ray Emission

Journal of Radioanalytical and Nuclear Chemistry - Elemental concentrations namely P, S, Cl, K, Ca, Sc, Ti, Mn, Fe, Cu, Zn, Rb, Br and Sr were determined using Particle Induced X-ray Emission...