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The approach to asymptotic critical behavior in polymer solutions is governed by a competition between the correlation length of critical fluctuations diverging at the critical point of phase separation and an additional mesoscopic length scale, the radius of gyration. In this paper we present a theory for crossover between two universal regimes: a regime with Ising (fluctuation-induced) asymptotic critical behavior, where the correlation length prevails, and a mean-field tricritical regime with theta-point behavior controlled by the mesoscopic polymer chain. The theory yields a universal scaled description of existing experimental phase-equilibria data and is in excellent agreement with our light-scattering experiments on polystyrene solutions in cyclohexane with polymer molecular weights ranging from 2×105 up to 11.4×106. The experiments demonstrate unambiguously that crossover to theta-point tricriticality is controlled by a competition of the two mesoscales. The critical amplitudes deduced from our experiments depend on the polymer molecular weight as predicted by de Gennes [Phys. Lett. 26A, 313 (1968)]. Experimental evidence for the presence of logarithmic corrections to mean-field tricritical theta-point behavior in the molecular-weight dependence of the critical parameters is also presented. [ABSTRACT FROM AUTHOR]

This paper presents a new method of deposition of diamond and diamond like structures by using the original reactor for activation of carbonaceous gas mixtures. One of the important characteristics of the described reactor is the power efficiency owing to low heat losses. The new method of gas flow formation opens new possibilities to get important trade-offs (wide range of background conditions and others). The principal possibility of diamond deposition is proved by experiments with the flow of hydrogen and methane mixture in tungsten resistively heating cylindrical channels. Electron microphotographs and Raman spectrum of deposited structures prove the fact that deposited samples are diamond structures. Numerical study of the mixture flow through the reactor was carried for optimization of gas flow conducted to a substrate. [ABSTRACT FROM AUTHOR]

A new setup OGRAN--the large scale opto-acoustical gravitational detector is described. As distinguished from known gravitational bar detectors it uses the optical interferometrical readout for registering weak variations of gravity gradient at the kilohetz frequency region. At room temperature, its sensitivity is limited only by the bar Brownian noise at the bandwidth close to 100 Hz. It is destined for a search for rare events--gravitational pulses coincident with signals of neutrino scintillator (BUST) in the deep underground of Baksan Neutrino Observatory of INR RAS. [ABSTRACT FROM AUTHOR]