The high-temperature Knudsen effusion method was used to study partial pressures of vapour species, activities of components and the Gibbs free energies in the DyF 3 -Dy 2 O 3 system at the temperature (1357 AE 5) K. Partial pressures of the vapour species were obtained by the ion current comparison method, with the DyF 3 partial vapour pressure over pure DyF 3 as a standard. The equilibrium constant of the gaseous reaction DyF 3 DyOF = Dy 2 OF 4 was evaluated. Thermodynamic data obtained are in a agreement with the available phase diagram of the DyF 3 -Dy 2 O 3 system. Results of the present study illustrate the negative deviations from the ideal behaviour in the system. #

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Approaches to estimate the number of almost periodic solutions of ordinary differential equations are considered. Conditions that allow determination for both upper and lower bounds for these solutions are found. The existence and stability of almost periodic problems are studied. The novelty of this paper lies in the fact that the use of apparatus derivatives allows for the reduction of restrictions on the degree of smoothness of the right parts. In the works of Lebedeva [1], regarding the number of periodic solutions of equations first order, they required a high degree of smoothness. Franco et al. required the smoothness of the second derivative of the Schwartz equation [2]. We have all of these restrictions lifted. Our new form presented also emphasizes this novelty.