On the 75th Birthday of Fcdor Maksimilianovich Kuni

June 25, 2006, was the 75th birthday of Fedor Maksimilianovich Kuni, Professor of the Chair of Statistical Physics, Department of Physics, St. Petersburg State University.

F.M. Kuni was born in Leningrad. In 1954, after graduating from the Department of Physics of Leningrad State University with honors, he started work at the Chair of Theoretical Physics, Leningrad State University, as an assistant lecturer. At the time, the main directions of research at this chair were associated with quantum mechanics and quantum field theory. Kuni also successfully started his scientific work in the field of dispersion relations in the quantum field theory under the guidance of Academician V. A. Fock and Professor Yu. V. Novozhilov. After defending his candidate's dissertation in 1959, Kuni became interested in problems of statistical mechanical description of inhomogeneous systems using the method of functional and diagrammatic expansions. Owing to his work in quantum field theory, Kuni had brilliantly mastered this technique, which thus served as a bridge to a new research field, and this held turned out to be very close to problems of colloid science. In this new sphere, he at once performed a fundamental investigation; calculated the asymptotics of a binary condition function and related it to the asymptotics of the pair interaction potential. This result opened the way to many applications, in particular, in the theory of surface layers. Starting from the middle of the 1960s, Kuni (in collaboration with A.I. Rusanov) solved many problems within the asymptotic molecular theory of surface layers, thin films, disperse systems, and porous bodies. In 1969 Kuni defended his doctoral dissertation on the statistical theory of molecular correlations in liquids and surface layers.

Since the beginning of the 1970s, Kuni has been interested in fundamental problems of non-equilibrium statistical mechanics. His first pupils and adherents were V.L. Kuz'min, L.Ts. Adzhemyan, B.A. Storonkin. and T.Yu. Novozhilova. In 1972. Kuni founded the Laboratory of Statistical Physics and Kinetics. The Chair of Statistical Physics was organized on the basis of this laboratory in 1975, and Kuni became its head.

In the second half of the 1970s, Kuni together with Storonkin solved complicated problems of rotational relaxation and light scattering in disperse media, worked together with Adzhemyan on fundamental problems of the dynamic derivation of nonlinear hydrodynamic equations, and gradually proceeded to thermodynamic and kinetic problems of first-order phase transitions (nucleation theory). Later, he created one of the world's leading schools on nucleation theory. His research in this field began with a detailed study (together with A.P. Grinin) of small parameters and description of the initial stages of non-steady-state homogeneous nucleation in supersaturated vapor. In the beginning of the 1980s, Kuni together with Rusanov and his pupil A.K. Shchekin developed the thermodynamic theory of nucleation on charged condensation nuclei. At the same time, he created the kinetic theory of heterogeneous condensation and, in particular, non-steady-state ion-induced nucleation under the conditions of instantaneously created vapor supersaturation. The next step was to design the non-steady-slate phenomenological theory of non-isothermal nucleation, which described the effects of the condensation heal in the case of instantaneous creation of vapor supersaturation. In the second half of the 1980s, a significant breakthrough was achieved in the kinetic theory of phase transitions after Kuni had found the solution to the problem of homogeneous nucleation under dynamic conditions that are widespread in nature, with the supersaturation emerging in the very process of the phase transition. In 1989-1991, Kuni in collaboration with A.P. Grinin and V.B. Kurasov generalized this theory for the case of condensation nuclei in metastable vapor and then successfully used it (together with A.P. Grinin, A.A. Melikhov, and Yu.V. Trofimov) for predicting the optimum regime of the purification of vapor mixture from the admixture vapor via the condensation and for describing the decomposition of a gas-supersaturated solution. Another crucial achievement of that time is the development of a method for complete separation of variables describing the state of a stable-phase nucleus in the Fokker-Planck multidimensional kinetic equation, which describes the overcoming of the activation barrier by nuclei owing to fluctuations. This result made it possible to solve a number of difficult two-dimensional problems in the theory of boiling-up in superheated liquids and nucleation in a two-component vapor mixture. Kuni in collaboration with Grinin derived and solved (1989-1992), with an accuracy sufficient for contemporary experiments, the kinetic equation of non-isothermal nucleation that lies beyond the limits of the Fokker-Planck approximation (contains higher order partial derivatives with respect to the temperature of nuclei).

In 1991-1995, Kuni together with Rusanov and Shchekin addressed to fundamental thermodynamic and kinetic problems of heterogeneous condensation on macroscopic nuclei. In this study, they revealed the role of disjoining pressure in the nucleation on insoluble wettable nuclei, developed the theory of nucleation on soluble surfactant nuclei with allowance for the adsorption and micellization of surfactants in the emerging droplets, and provided the first description of non-steady-state condensation kinetics on soluble nuclei. Further, Kuni generalized the theory of nucleation under dynamic conditions for the case of macroscopic nuclei of various kinds. Since the end of 1990s and till now, Kuni focused his attention on the aggregation and micellization processes in surfactant solutions. He proposed a method for double-flux description of overcoming the potential barrier of aggregation work by surfactant aggregates in the kinetics of the formation of spherical and cylindrical micelles. He also developed the kinetic theory of relaxation in micellar systems.

Kuni's scientific style is characterized by his ability to grasp a physical problem, provide its mathematical formulation, and then find its exhaustive solution in spite of any difficulties. Open-handedly sharing his ideas with the pupils, Kuni has trained a real cohort of professors, and, when time came, he relinquished his duties as head of the Chair of Statistical Physics 10 one of them (A.P. Grinin). But Kuni is still a professor of this chair and works just as fruitfully, publishing up to ten papers each year.

Since 1976 Kuni has been Chairman of the Dissertation Council at Saint-Petersburg State University for Doctoral Dissertations on Condensed-State Physics, Semiconductor Physics, and Macromolecular Compounds.

As an award for scientific achievements and many years of work at St. Petersburg State University, Kuni received the Honorary Diploma of this university in 1978 for high teaching skills and training scientists. In 1999, he was given the title of Honored Worker of Science of the Russian Federation.

Kuni's highest scientific qualification, firm principles, and kind attitude have made him a deeply respected person among all people who worked or communicated with him. He is celebrating his jubilee in the midst of active and fruitful scientific work. We wish Fedor Maksimilianovich many more happy years of creative inspiration and new achievements for the benefit of Russian and world science.

COLLOID JOURNAL, 2006.