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41.
The exchange of Na+ ions of vermiculite for Co2+ cations is measured by sorption-analytical and microcalorimetric methods. The previously revealed growth of the equilibrium constant with a rise in the degree of filling θ of vermiculite exchange sites with Co2+ cations is confirmed. This result is explained by the segregation of Co2+ and Na+ cations being exchanged in separate interlayer regions of vermiculite. The negative heats of exchange of Na+ cations for Co2+ cations are associated with the energy consumption for the rearrangement of the segregated interlayer regions in vermiculite. The positive entropy changes resulting from the exchange indicate the formation of a more disordered Co-Na-layered “cake” in comparison with the initial Na-form vermiculite. A decrease in the integral molal free-energy change ΔG m of the mixed form of the mineral is determined by the entropy factor. It is shown that, as θ increases, the ΔG m(θ) dependence passes from a positive to a negative range of values. This pattern of the curve may be interpreted as a gradual phase transition from the Na-form to the mixed Co-Na-segregated form. The first derivatives of the enthalpy and entropy changes with respect to the degree of filling θ exhibit distinct maxima at θ ~ 0.20 as a result of the transition from the ideal mixing of Co2+ and Na+ cations being exchanged to their segregation. 相似文献
42.
Polyakov K. M. Mordkovich N. N. Safonova T. N. Antipov A. N. Okorokova N. A. Dorovatovskii P. V. Veiko V. P. 《Crystallography Reports》2021,66(5):786-790
Crystallography Reports - Crystals of mutants of uridine phosphorylase from Shewanella oneidensis MR-1 at the active-site threonine residue were obtained, and the three-dimensional structures of... 相似文献
43.
A. M. Polyakov 《Journal of Geometry and Physics》1988,5(4):595-600
We analyze three-dimensional gauge theory with Chern-Simons action, which arises in the context of high Tc superconductivity. We show that the main effect in this theory is the change of spin and statistics of charged particles. Also, the amplitudes of particle propagation acquire phases dependent on the topology of the knot formed by their trajectories. In the end, we discuss possible generalizations of this theory, and their relations to strings. 相似文献
44.
We discover that some unstable vacua have long memory. By that we mean that even in the theories containing only massive particles, there are correllators and expectation values which grow with time. We examine the cases of instabilities caused by the constant electric fields, expanding and contracting universes and, most importantly, the global de Sitter space. In the last case the interaction leads to a remarkable UV/IR mixing and to a large back reaction. This gives reasons to believe that the cosmological constant problem could be resolved by the infrared physics. 相似文献
45.
The influence of structurally different dihydric phenols on the radical reactions of hexane in deaerated solutions under -irradiation was studied. It was found that 4-tert-butylpyrocatechol (I), 3,5-diisopropylpyrocatechol (II), 2,5-di-tert-butylhydroquinone (III), and 4,6-di-tert-butylresorcinol (IV) effectively inhibited the formation of hexyl radical combination products. Using the chromatography–mass spectrometry technique, it was shown that the adducts of alkyl radicals with I–III have the structure of a monoalkyl ether. Phenol IV gave a mixture of dimers with O- and C-alkylation products. 相似文献
46.
Polyakov S Malendevich R Jankovic L Stegeman G Bosshard C Gunter P 《Optics letters》2002,27(12):1049-1051
The generation of multiple quadratic spatial solitons aligned approximately along a crystal axis in a biaxial noncritically phase-matched crystal is shown theoretically and experimentally to be the consequence of anisotropic diffraction. 相似文献
47.
Coincidence Mössbauer spectroscopy (CMS) in the presence of a hyperfine field and electronic spin relaxation is discussed. The resulting expression for the transmission through a resonant absorber as a function of time is found with the help of the joint solution of the Maxwell equations and the density matrix equations. It is shown that the radiation that reaches the detector behind the absorber is modulated by the hyperfine field. The various polarization schemes for the CMS observation are analyzed. Numerical calculations were made for an57 Fe nucleus. 相似文献
48.
49.
V. N. Polyakov 《Mathematical Notes》1971,9(2):101-106
The construction of a bounded operator in terms of its characteristic function is investigated.Translated from Matematicheskie Zametki, Vol. 9, No. 2, pp. 171–180, February, 1971. 相似文献
50.
V. A. Polyakov 《Mechanics of Composite Materials》1969,5(5):794-801
Retaining the fundamental assumption z=0, the author investigates two-dimensional problems of the bending of cylindrically orthotropic circular plates in relation to the anisotropy parameter k=E/Er and a generalized parameter depending both on the transverse shears and the dimensions of the plates h2/a2×Er/Grz. Equations are given for calculating certain quantities from the classical variant of the solutions. There are shown to be important differences in the solutions for boundary conditions of the clamped-edge type (when a horizontal or vertical element of the edge is fixed). The effect of the stress z is estimated from the standpoint of the Ambartsumyan theory [2]. Two types of loading, a distributed load q=const and a concentrated load P applied at the center of the plate, are considered.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 5, pp. 899–908, September–October, 1969. 相似文献