Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

Avoiding interactional conflict in dementia: the influence of gender styles on interactions.

Sociolinguistic research in the general population has established the existence of gender differences in the social use of language. In particular, it has been noted that women use more markers of politeness, small talk and structural devices (e.g. minimal responses, tag questions) to help maintain their conversations. Analysis of interactions involving people with dementia (PWD) suggests that these gender based differences were still present in the face of dementia. Furthermore, the use of these forms of language helped the women with dementia to avoid conflict and extend the length of their interactions. This study investigated whether the use of such language helped or hindered women with dementia in maintaining conversational satisfaction

Ab Initio and Density Functional Predictions of Solvation Free Energies of Cyclic Polyethers (CH2CH2O)n (n=2,6) in Aqueous and Tetrachloromethane Solutions

Solvation free energies ΔGsoltot of cyclic polyethers (CH2CH2O)n (n=2,6) in aqueous and tetrachloromethane solutions have been calculated at HF, MP2 and B3LYP/6-311G (d,p) levels of theory using CPCM, IEFPCM and SMD implicit solvation models. It has been found that ΔGsoltot are negative for both solvents, they increase linearly with system sizes and they are more important in water solution. The electrostatic contributions to the solvation free energies ΔGsolele are also more important in water because of their polar nature. In water, CPCM and IEFPCM models give a close values, which are slightly different from SMD values. In tetrachloromethane solvent CPCM model seems overestimate ΔGsolele. For both solvents the non-electrostatic contributions to the solvation free energies ΔGsoln-ele provided by SMD are remarkably different to those given by CPCM and IEFPCM models

Preparation and characterization of green adsorbent on functionalized and nonfunctionalized ALOE VERA: A combined experimental and DFT calculations

International audienceAn influential subject of research is the preparation of raw Aloe-Vera (AV) which is characterized by FTIR, XRD, SEM, and BET and its use as a biosorbent for the effective removal of Pb(II) and Cd(II) ions from an aqueous solution. The adsorption study was studied using UV-visible (UV/Vis) spectroscopy. The adsorption capacity of Pb(II) by AV is 36.33 mg/g (95,79%) was obtained at 20 min at acidic pH = 3, whereas the optimal sorption of Cd(II) is 16.92 mg/g (81.54%) at 15 min at pH = 6 with a mass of adsorbent of 0.05 g and metal ion concentration of 5.10-4 M at 20 • C. Thermodynamic studies have proven that the removal of Pb (II) and Cd (II) using AV is spontaneous, endothermic, and physical in nature. The adsorption kinetics follows the pseudo-second-order process and the isotherm adsorption was most accurately described by the Freundlich model. On the other hand, based on the enormous power of the density functional theory as a tool in the adsorption phenomena, which has been greatly improved by their applications to organic and inorganic adsorption design. The functionalB97D3 with 6-311++G**/land2dz//SMD basis set and solvent model is used using descriptors as molecular, electronic, and reactivity indices