The influence of grafted functional groups on the adsorption properties of silica

The adsorption properties of silica gel with grafted aminopropyl and guanidinoethanethiol (GET) groups were studied by the techniques of adsorption under static conditions and gas chromatography. It was shown that molecules capable of forming hydrogen bonds are adsorbed on all modified samples more weakly than on the initial silica gel. The grafting of GET radicals on the surface results in a noticiable increase in the dispersion interaction with adsorbed molecules. Calculation of the contributions of molecular groups to the constant of adsorption equilibrium showed that the thermodynamic characteristics of adsorption on aminosilochromes and aminosilicas with a polymeric layer of the modifying agent have similar values. Such adsorbents can be used for investigation of polar compounds, including organic bases. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 452–457, March, 1997.     

Complexation behaviour of benzilmono(Iepidyl)hydrazone (BLH) toward bivalent metal ions: A potentiometric study

Potentiometric investigations on metal complexes of various bivalent metal ions, viz. UO₂(II), Cu(II), Ni(II), Co(II), Cd(II), Pb(II), Zn(II) and Mn(II) with benzilmonol(lepidy!)hydrazone (BLH) have been carried out at different ionic strengths and at different temperatures in order to determine stability constants of the complexes. Thermodynamic parameters ΔC, ΔH and ΔS have also been evaluated from temperature coefficient data. The effect of varying the dielectric constant of the medium on the stability constants of complexes has also been investigated at 30±0.5°C and μ = 0.1MNaCl. Thermodynamic stability constants and thermodynamic stabilization energies for the first transition metals have also been discussed.     

Lattice dynamical study of body-centred tetragonal indium

The phonon dispersion curves, phonon frequency distribution function as well as the lattice specific heat of body-centred tetragonal indium have been deduced using a lattice dynamical model which includes central, angular and volume forces. Six elastic constants, four zone boundary frequencies and an equilibrium condition were used in the evaluation of the force constants. It is shown that this model is elastically consistent and satisfies the symmetry requirements of the lattice, the phonon frequencies of indium deduced from it are in very good agreement with the experimental values of Reichardt and Smith and the theoretical values of Garrett and Swihart, and theθ _D values compare well with the experimental values over a wide temperature range. The apparent discrepancies in the phonon dispersion curves and theθ _D-T curves obtained from deficient models, importance of umklapp processes and the significance of angular forces in the lattice dynamical models are discussed.     

Solubility of 1-Butene in Water and in a Medium for Cultivation of a Bacterial Strain

Solubility measurements of 1-butene in water, from 20 to 50°C and at atmospheric pressure, were carried out using a Ben-Naim/Baer-type apparatus. The experimental results have a precision of about ±0.3%. Using accurate thermodynamic relations, the Ostwald coefficients at the experimental conditions and at infinite dilution, the mole fractions of the dissolved gas at the gas partial pressure of 101.325 kPa and the Henry coefficients at the water vapor pressure were calculated. The mole fraction of dissolved gas were fitted to the Clarke, Glew, and Weiss equation and thermodynamic quantities, standard molar Gibbs energy, entropy, and enthalpy changes, for the process of transferring the 1-butene molecules from the gaseous to the water phase, were computed. Moreover, solubility measurements of 1-butene in an aqueous medium for the cultivation of Xanthobacter Py2 in the same temperature range were also performed at atmospheric pressure. These solubility data are approximately 2.6% lower than those observed in pure water.     

Stabilization of a high energy molecular conformation by specific intermolecular forces, a novel planar benzylideneaniline system

The system containing six benzylideneanilines (BA) has been studied: Group 1:

Surface forces in wetting films

A short review of various components of surface forces acting in a non-symmetrical system such as wetting films is presented here. Experimental results are compared with modified DLVO theory, which includes, besides dispersion and electrostatic, structural (solvation) forces caused by a change in liquid structure in conditions of confined geometry. The peculiarities of disjoining pressure isotherms and conditions of the film stability of non-polar and polar simple liquids, as well as of aqueous solutions of electrolytes and surfactants, are systematically considered from a historical perspective.     

Effect of Insoluble Surfactants on Drainage and Rupture of a Film between Drops Interacting under a Constant Force

The deformation, drainage, and rupture of an axisymmetrical film between colliding drops in the presence of insoluble surfactants under the influence of van der Waals forces is studied numerically at small capillary and Reynolds numbers and small surfactant concentrations. Constant-force collisions of Newtonian drops in another Newtonian fluid are considered. The mathematical model is based on the lubrication equations in the gap between drops and the creeping flow approximation of Navier–Stokes equations in the drops, coupled with velocity and stress boundary conditions at the interfaces. A nonuniform surfactant concentration on the interfaces, governed by a convection–diffusion equation, leads to a gradient of the interfacial tension which in turn leads to additional tangential stress on the interfaces (Marangoni effects). The mathematical problem is solved by a finite-difference method on a nonuniform mesh at the interfaces and a boundary-integral method in the drops. The whole range of the dispersed to continuous-phase viscosity ratios is investigated for a range of values of the dimensionless surfactant concentration, Peclét number, and dimensionless Hamaker constant (covering both “nose” and “rim” rupture). In the limit of the large Peclét number and the small dimensionless Hamaker constant (characteristic of drops in the millimeter size range) a fair approximation to the results is provided by a simple expression for the critical surfactant concentration, drainage being virtually uninfluenced by the surfactant for concentrations below the critical surfactant concentration and corresponding to that for immobile interfaces for concentrations above it.     

Kinetics and thermodynamics of the electrodeposition of palladium, thallium, and tellurium from different baths

Some kinetic and activation thermodynamic functions for the electrodeposition of palladium, thallium, and tellurium from the best selected baths, viz. niclosamide bath [5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide] for Pd, alizarin red bath for Tl, and salicylaldehyde bath for Te, are determined. Reaction rate constant (k), half-lifetime (t _1/2), activation energy (E _a), and such activation thermodynamic parameters as entropy change (ΔS*), enthalpy change (ΔH*), and Gibbs free energy (ΔG*) are calculated by applying the rate theory of the first-order reaction and the Eyring theory of the reaction rate. The effect of temperature change in the range of 30–60°C on the above parameters is studied and thoroughly discussed. The effect of metal type on both the reaction rate and the activation energy is also investigated. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 3, pp. 264–271. The text was submitted by the authors in English.     

On the ν-dimensional one-component classical plasma: The thermodynamic limit problem revisited

We prove theH-stability property and the existence of the thermodynamic limit of the free energy density of the two-dimensional, one-component classical plasma. We give lower and upper bounds on the free energy density in any dimensionv and draw some consequences.