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Vol 484, No 1 (2019)
- Year: 2019
- Articles: 6
- URL: https://journals.rcsi.science/0012-5016/issue/view/9255
Physical Chemistry
Hydro-Osmotic Pressure
Abstract
The term hydro-osmotic pressure is proposed to be introduced to describe the hydrostatic pressure developing in the osmotic process during the diffusion of the solvent through the membrane. Using this term allows one to avoid the ambiguity in using the term osmotic pressure. The osmotic pressure characterizes the concentration of solutes in the solution, regardless of the existence of hydrostatic pressure. The hydro-osmotic pressure is the difference between the hydrostatic pressures on both sides of the membrane. The term hydro-osmotic pressure most correctly characterizes the essence of many processes occurring in osmotic phenomena.
1-3
4-7
Structure and Thermal Properties of TmFe2O4 at Various Temperatures and Oxygen Pressures
Abstract
The stability range of TmFe2O4 was studied at a temperature of 1090°C and reduced oxygen pressure in the gas phase. Using experimental data obtained for TmFe2O4 dissociation in the temperature range of 750–900°C, its thermodynamic characteristics were calculated. The structural transformations in the temperature range from –140 to 140°C associated with charge ordering in this compound were identified.
8-11
Heat Capacity and Thermal Expansion of Yttrium Tantalate
Abstract
The isobaric heat capacities of two monoclinic (M' and M) modifications of yttrium orthotantalate at temperatures 5–1300 K have been measured by the adiabatic and differential scanning calorimetry methods. It has been demonstrated that the difference in structure between the crystal lattices of M' and M has little effect in the heat capacity, and the difference between the heat capacities of these phases Cp(M) – Cp(M') is small, always positive, and increases in the range of the lowest temperatures. The unit cell parameters of M-YTaO4 have been determined as a function of temperature in the range 300–1173 K.
12-14
Solid-State Catalytic Isotope Exchange of Hydrogen for Deuterium in Cyclopropylglycine
Abstract
The reaction of spillover hydrogen (SH) with cyclopropylglycine (cPG) in high-temperature solid-state catalytic hydrogen isotope exchange (HTCIE) has been studied experimentally and using density functional theory (DFT). NMR spectroscopy and mass spectrometry have shown a high regioselectivity and stereoselectivity for the reaction of spillover hydrogen with cPG fragments. The Gly fragment has been shown to be the most reactive in HTCIE, for which high stereoselectivity of substitution of hydrogen by deuterium has been demonstrated.
15-19
Features of Haloalkane Effect on the Concentration Limits and Induction Time for the Ignition of Methane–Oxygen Mixtures
Abstract
A strong difference in the character of admixture effect on ignition by shock wave and spark initiation has been revealed using the haloalkane effect on the ignition of methane–oxygen mixtures as an example. It has been shown that the difference is determined by the presence of considerable concentrations of reactive intermediate species in an initial mixture, the qualitative difference in gas heating modes, and the strong difference between the temperature ranges of the processfor two these methods.
20-22