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Alekseechkin N.V.,National Science Center Kharkov Institute of Physics and Technology
Journal of Physical Chemistry B | Year: 2012

The multivariable theory of nucleation (J. Chem. Phys.2006, 124, 124512) is applied to the problem of vapor bubbles formation in pure liquids. The presented self-consistent macroscopic theory of this process employs thermodynamics (classical, statistical, and linear nonequilibrium), hydrodynamics, and interfacial kinetics. As a result of thermodynamic study of the problem, the work of formation of a bubble is obtained and parameters of the critical bubble are determined. The variables V (the bubble volume), ρ (the vapor density), and T (the vapor temperature) are shown to be natural for the given task. An equation for the dependence of surface tension on bubble state parameters is obtained. An algorithm of writing the equations of motion of a bubble in the space {V, ρ, T}-equations for V̀, ρ̀, and T̀-is offered. This algorithm ensures symmetry of the matrix of kinetic coefficients. The equation for T̀ written on the basis of this algorithm is shown to represent the first law of thermodynamics for a bubble. The negative eigenvalue of the motion equations which alongside with the work of the critical bubble formation determines the stationary nucleation rate of bubbles is obtained. Various kinetic limits are considered. One of the kinetic constraints leads to the fact that the nucleation cannot occur in the whole metastable region; it occurs only in some subregion of the latter. Zeldovich's theory of cavitation is shown to be a limiting case of the theory presented. The limiting effects of various kinetic processes on the nucleation rate of bubbles are shown analytically. These are the inertial motion of a liquid as well as the processes of particles exchange and heat exchange between a bubble and surrounding liquid. The nucleation rate is shown to be determined by the slowest kinetic process at positive and moderately negative pressures in a liquid. The limiting effects of the processes of evaporation-condensation and heat exchange vanish at high negative pressures. © 2012 American Chemical Society. Source


Uvarov D.V.,National Science Center Kharkov Institute of Physics and Technology
Nuclear Physics B | Year: 2010

The Type IIA superstring action on the AdS4 × CP3 background, obtainable by the double dimensional reduction of the AdS4 × S7 supermembrane, is considered in the κ-symmetry light-cone gauge, in which the light-like directions are chosen on the D = 3 Minkowski boundary of AdS4. Such choice of the gauge condition relies on representing the AdS4 × S7 background isometry superalgebra osp (4 | 8) (and correspondingly the osp (4 | 6) isometry superalgebra of the AdS4 × CP3 background) as D = 3 extended superconformal algebra. The gauge-fixed action includes contributions up to the 4th power in the fermions. © 2009 Elsevier B.V. All rights reserved. Source


Alekseechkin N.V.,National Science Center Kharkov Institute of Physics and Technology
Journal of Non-Crystalline Solids | Year: 2011

A solution of the problem of calculating the volume fraction of a phase growing by a diffusion-type law is given. This is meant that the growth velocity Ṙ of a nucleus is a decreasing function of its radius R. The growth law Ṙ~1/Rn-1, n > 1, is employed for demonstrative calculations. The solution is obtained in the framework of the classical Johnson-Mehl-Avrami approach which uses the concept of non-physical phantom nuclei. Probabilistic treatment of this approach is offered and the necessity of phantom nuclei is confirmed. The Johnson-Mehl-Avrami approach is compared with Kolmogorov's method and its extension - the differential critical-region method; the latter yields the same equations for the volume fraction. In the case of the growth law considered, phantom nuclei contribute to the incrementing of the transformed volume fraction. The obtained equations for the volume fraction are shown to cancel this contribution; hence they yield the true value of this quantity. Two successive approximations for the volume fraction are considered analytically and the numerical evaluation of the effect of phantom nuclei is given for different values of n. © 2011 Elsevier B.V. All rights reserved. Source


Uvarov D.V.,National Science Center Kharkov Institute of Physics and Technology
Nuclear Physics B | Year: 2013

Massless superparticle model is considered on the OSp(4|6)/(SO(1, 3) × U(3)) supercoset manifold and in the AdS4×CP3 superspace. In the former case integrability of the equations of motion is rather obvious, while for the AdS4×CP3 superparticle we prove integrability in the partial κ-symmetry gauge for which 4 anticommuting coordinates related to the broken conformal supersymmetry are set to zero. This allows us to propose expression for the Lax pair that may encode complete equations of motion for the AdS4×CP3 superparticle. © 2012 Elsevier B.V. Source


Bondarenco M.V.,National Science Center Kharkov Institute of Physics and Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

At measurements of the spectra of intense gamma radiation produced by ultrarelativistic electrons in periodic structures, pileup of arrivals to the detector of several photons from one electron can cause significant deviations of the measured spectrum from the classically evaluated one. The description of experiments then requires summation of all multiphoton contributions. We describe the corresponding resummation procedure for the photon spectral intensity, as well as for the photon multiplicity spectrum, and apply it to the study of radiation spectra with a mix of coherent and incoherent contributions. The impact of multiphoton effects on the radiation spectrum shape is investigated. The limit of high photon multiplicity for the coherent part of the radiation is explored in detail. A method for reconstruction of the underlying single-photon spectrum from the multiphoton one is formulated. © 2014 American Physical Society. Source

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