On the theory of flow of an incompressible viscous fluid in a channel of arbitrary section

An exact solution is constructed to the problem of the stationary flow of an incompressible viscous fluid in a straight tube whose section is formed by two connected rectangles.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 124–128, March–April, 1980.     

Sensitive coating for water vapors detection based on thermally sputtered calcein thin films

In this paper the adsorption properties of thermally sputtered calcein thin films towards water and other polar molecules vapors are studied by different characterization techniques: quartz crystal microbalance, surface plasmon resonance and visible spectroscopy. Sensitivity of calcein thin films to water vapors resulted much higher as compared with those of a number of dyes whose structure was close to that of calcein. All types of sensors with calcein coatings have demonstrated linear concentration dependences in the wide range of water vapor pressure from low concentrations up to 27,000 ppm (close to saturation). At higher concentrations of water vapor all sensors demonstrate the abrupt increase of the response (up to two orders). A theoretical model is advanced explaining the adsorption properties of calcein thin films taking into account their chemical structure and peculiarities of molecular packing. The possibility of application of thermally sputtered calcein films in sensing technique is discussed.     

Investigation of structural evolution of hydrogen-bond networks of water clusters at 1 and 300 K

Computer simulation of water clusters (H₂O) _n , Na⁺(H₂O) _n and K⁺(H₂O) _n (n ?? 8) at temperatures of 1 and 300 K was carried out using the Monte Carlo method. All the types of the hydrogen-bond network structures at equilibrium configurations of the water clusters and, among them, the most probable ones at temperatures of 1 and 300 K, were detected. The analysis of the most probable types of hydrogen-bond networks at equilibrium configurations of water clusters revealed that clusters with n water molecules inherit the configuration of clusters with n ? 1 water molecules with an accuracy of one hydrogen bond.     

Functional integral method for investigating the dynamics of a Dicke type model

Conclusions The approach to the investigation of nonequilibrium systems proposed in this paper has made it possible to treat fairly readily the dynamics of a Dicke type model in the thermodynamic limit. A number of other model systems can be investigated similarly. The results obtained from the expression for the generating functional of the temperature-time Green's functions generalize the corresponding result of [4]. Exact study of the dynamical behavior of the Dicke type model at large times has shown that it possesses different nonlinear dynamical regimes, the conditions for the existence of which depend strongly on the initial values of the parameters of the system and the statistics of the fields. The point of bifurcation of the dynamics is an analog of the critical temperature for an equilibrium phase transition.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 69, No. 2, pp. 279–286, November, 1987.     

Effect of the Nature of the Dopant on the Response of a Sensor Array Based on Polyaniline

The effect of the nature of the dopant on the response of a sensor array based on films of polyaniline (PAn) under the influence of the vapor of various organic solvents was studied. It was established that the main factors determining the magnitude of the response of PAn films are the morphology of the films and the accepting power of the analyte molecules (in the case of "standard" acid dopants) and also the possibility of additional donor–acceptor interaction between the analyte molecules and the dopant (in the case of heteropoly acid dopants). It was shown that with heteropoly acids as dopants of PAn it is possible to increase substantially the selectivity of the response of the sensor array.     

Concentration of gold nanoparticles in the QCM sensitive film as a factor of adsorption properties controlling

The adsorption properties of sensitive films formed by gold nanoparticles, dropped from solutions with different nanoparticles content are investigated using mass-sensitive (QCM) sensors. The dependence of surface adsorption capacity on nanoparticles concentration is shown. The decrease of surface concentration of nanoparticles leads to the increase of sensors sensitivity to different alcohols and water. The adsorption character of water (response amplitude and kinetics) substantially differs form that of alcohols. The sensitivity of gold nanoparticles layers to water is more then one order higher then to alcohols. The kinetics of water adsorption runs in two stages.