Russian Journal of Physical Chemistry A最新文献

Potentiometry and calorimetry are used to study the Ni²⁺–diglycine–L-histidine system in an aqueous solution at T = 298.15 K (KNO₃). The composition and stability of the mixed ligand complex Ni(GG)(His) are defined with potentiometric measurements. The study is performed at ratios Ni : (GG + His) = 1 : 4 and 1 : 6. The concentrations of diglycine and L-histidine are in ratios of 3 : 1 and 5 : 1. The values of (log beta ) obtained at different ratios of diglycine and L-histidine agree well with one another. Thermal effects are measured in the ampoule of a mixing calorimeter with an isothermal shell, a thermistor temperature sensor, and automatic recording of the temperature/time curve. The thermal effects of mixing solutions of Ni(NO₃)₂, diglycine, and L-histidine in the ratio (c_{{{text{Ni}}}}^{0}) : (c_{{{text{GG}}}}^{0}) : (c_{{{text{His}}}}^{0}) = 1 : 3 : 1 are measured to determine the enthalpy of formation of a Ni(GG)(His) particle. The experiments are performed at ionic strengths of 0.2, 0.5, and 1.0 (mol/L). The standard thermodynamic characteristics (Δ_rH°, Δ_rG°, Δ_rS°) of the formation of a mixed-ligand complex are determined. A comparative analysis of the obtained data is performed using thermodynamic characteristics of mixed-ligand complexation in the Ni²⁺–glycine–L-histidine and Ni²⁺–triglycine–L-histidine studied earlier. Structures of forming complexes are proposed.

Studies of intermolecular interactions in butyl acetate-dibutyl phthalate and butyl acetate-dioctyl phthalate systems show that except for excess volume, deviations of properties from an ideal mixture are reduced as the temperature rises. Results indicate considerable van der Waals forces and confirm the effect the size of molecules has on the properties of binary mixtures. Experimental data on density, refractive index, viscosity, excess molar volume, and other properties are presented for systems and pure substances.

An investigation is performed of the effect the treatment of a pulsed plasma flow has on samples of two shapes (flat and cylindrical) made of structural steels (St45, 40Kh, 65G, ShKh15, 40KhN2MA). Processing is done under different conditions with varying parameters (pulse duration, capacitor bank charging voltage, and the type of working gas). Data show that after treatment, corrosion resistance increases for most of the considered grades of steel. The most effective processing parameters are established for each grade of steel.

Our current study employs the spin-polarized density functional theory (DFT) using the all-electron full potential linear augmented plane-wave method (FP-LAPW) to examine the structural, electronic, and magnetic properties of InSb doped with Tungsten (In(_{{1 - x}})W_xSb with x = 0.125, 0.25) in the zinc blende crystal structure. We used, for the electronic exchange and correlation energy, the generalized gradient approximation (GGA) with the Wu-Cohen (WC) functional, improved with the Tran–Blaha modified Becke–Johnson (TB-mBJ) approach for the electronic properties. The obtained results show that this calculation method allows for reliable band gap values. The estimated structural properties match well with existing experimental results. The value of the total magnetic moment is around 3.00 µB for the investigated compounds, and because of their half-metallic ferromagnetic properties, they are regarded prospective candidates for spintronic applications.

The authors analyze temperature dependences of the retention of derivatives of quinoline, 1,2,3,4-tetrahydroquinoline, and pyridazino[4,5-c]quinoline under conditions of reversed-phase high-performance liquid chromatography on octadecyl silica gel. The thermodynamic characteristics of sorption of these compounds are calculated. The change in the enthalpies of sorption are found to depend on the content of acetonitrile in the water–acetonitrile eluent.

The authors continue their set of studies on the separation of boron isotopes by means of chemical exchange in liquid–liquid systems using tri-n-octylamine as the main component of the organic phase. Degree of separation K = 1.0961 ± 0.0016 was obtained using experimental modeling of the operation of a rectangular cascade for separating boron isotopes in a 30-h long period of separation in the mode of product extraction. The obtained data are used to determine period τ = 19–21 h of concentration needed to reach a steady state when operating with product extraction at maximum degree of separation K_m = 1.109. The time needed to reach a steady state is τ = 130–160 h when operating in the mode without product extraction, which corresponds to maximum degree of separation K_m = 1.131.

Composite catalyst (CC) Ni/HMOR/({text{SO}}_{4}^{{2 - }})–ZrO₂ is used to study the hydroconversion of benzene and toluene at atmospheric pressure, a temperature of 180°C, WHSV = 2 h⁻¹, and Н₂/ArH = 8. The conversion of benzene is as high as 58.2%. Adding an alkyl substituent raises conversion to 78.5%. It is shown that the primary conversion of toluene is similar to the conversion of benzene through selective aromatic ring hydrogenation with its subsequent isomerization, ring reduction, and hydrocleavage. Components of the catalytic system are inactive in the hydroconversion of aromatic hydrocarbons. Synergism emerges in the hydrogenating CC activity due to the cojoint effect which individual inactive ({text{SO}}_{4}^{{2 - }})–ZrO₂ and Ni/HMOR components of this system have on the reaction. The probable mechanism of the hydrogenation of aromatic hydrocarbons is discussed. It is hypothesized that hydrogenating activity synergism results from the radical reaction becoming one of an ion radical.

The non-exchangeable sorption of tryptophan by the AV-17-2P anion exchanger from solutions of different compositions was studied. The sorption of the amino acid was shown to be independent of the nature of the accompanying component. This was explained by quantum-chemical modeling, which gave variants of attachment and energy characteristics of the bonds formed in the sorbent phase during non-exchangeable sorption of tryptophan by a highly basic anion exchanger in the salt form. The polar interactions play the major role, and π–π interactions produce an additional effect during the non-exchangeable sorption of amino acids on highly basic aromatic anion exchangers.

Results are presented from measuring optical density in the ultraviolet (UV) and visible ranges of polymer films made of polysulfone (PSF), polymethyl methacrylate (PMMA) and polyvinyl alcohol (PVA) with embedded CNTs, produced by mixing solutions. It is found that adding CNT increases the optical density of polymers, and the efficiency of absorption depends on the choice of polymer. Coefficients of extinction are calculated for CNT in PSF, PMMA, and PVA. The results can be used to develop a way of monitoring the homogeneity of CNT distribution in polymer films.

A comparatively simple method for estimating the mixing enthalpy of melts by differential scanning calorimetry using standard equipment is proposed. The enthalpies of mixing of CsX–PbX₂ (X = Cl, Br) melts are determined by this method. The measured values of mixing enthalpy in the CsCl–PbCl₂ system are in good agreement with those obtained by means of independent measurements. For the CsBr–PbBr₂ system, the enthalpy of mixing was measured for the first time. The similar values of mixing enthalpy were found for both studied systems.