We studied the effect of different concentrations of polyelectrolytes poly(allylamine hydrochloride) (PAH) and polystyrene sulfonate (PSS) as well as the effects of microcapsules coated with these polymers on survival of Ehrlich ascites carcinoma cells and mouse peritoneal macrophages and on ROS production by phagocytes. PAH reduced viability of Ehrlich ascites carcinoma in a concentration-dependent manner (LD50=12-15 μg/ml). This effect was presumably determined by its ability to bind phosphates, thereby depleting the culture medium. At the same time, PAH did not affect the viability of macrophages. PSS produced no cytotoxic effect on the examined cells. Polyelectrolyte capsules with the shell architectonics (PAH/PSS)3 and (PAH/PSS)3PAH in the examined concentration range had no effect on the viability of macrophages and tumor cells. PAH microcapsules with positively charged surface much more rapidly and more intensively activated macrophages. The chemiluminescence response directly depended on the amount of capsules in the solution.

Relationship between changes in the erythrocyte sedimentation rate in rats and concentration and charge of polyelectrolyte microcapsules was studied by the Panchenkov method. Positively charged microcapsules reduced erythrocyte sedimentation rate in a concentrationdependent manner. This effect was related to a decrease in the content of high-molecularweight proteins in the plasma due to their adsorption in positively charged microcapsules with polyacrylamide surface layer.

Multi-variant three-dimensional numerical simulations demonstrate the feasibility of the continuous- detonation process in an annular combustor of a ramjet power plant operating on hydrogen as fuel and air as oxidant in conditions of flight at a Mach number of M 0 = 5.0 and an altitude of 20 km. Conceptual schemes of an axisymmetric power plant, 400 mm in external diameter and 1.3 to 1.5 m in length, with a supersonic intake, divergent annular combustor, and outlet nozzle with a frusto-conical central body are proposed. Calculations of the characteristics of the internal and external flows, with consideration given to the finite rate of turbulent-molecular mixing of the fuel mixture components with each other and with the combustion products, as well as the finite rate of chemical reactions and the viscous interaction of the flow with the bounding surfaces, have shown that, in these flight conditions, the engine of such a power plant has the following performance characteristics: the thrust, 10.7 kN; specific thrust, 0.89 (kN s)/kg; specific impulse, 1210 s; and specific fuel⋅consumption 0.303 kg/(N h). In this case, the combustor can operate with one detonation wave traveling in the annular channel at an average velocity of 1695 m/s, which corresponds to a detonation wave rotation frequency of 1350 Hz. It is shown that, an operating combustor has regions with subsonic flow of detonation products, but the flow is supersonic throughout its outlet section.

To verify the predictability of a computational technology developed at the Semenov Institute of Chemical Physics, Russian Academy of Sciences, three-dimensional calculations of the operation process in a hydrogen-air continuous detonation combustor (CDC) of the Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences have been conducted with the reproduction of the geometrical dimensions of all the elements of the experimental combustor and the main operating conditions. The calculation results are in good agreement with the experiment data on all the measured characteristics. The problem of the applicability of a planar two-dimensional approximation with periodic boundary conditions to the simulation of the physicochemical processes in an annular CDC has been specifically studied. It has been shown that the distributions of density, temperature, Mach number, and axial velocity component in the different sections of the combustor are substantially three-dimensional, whereas the static pressure distribution approaches a two-dimensional pattern with increasing distance from the bottom of the CDC. The three-dimensional calculations have shown that the conventional assumption of a supersonic discharge at the outlet of a two-dimensional computational domain is not always correct: extensive zones of a subsonic discharge of detonation products can exist in the outlet section.

The enzyme urease and paramagnetic Fe3O4 particles were incorporated into microcapsules (3-4 m in size) formed using sodium polystyrene sulfonate and polyallylamine hydrochloride polyelectrolytes. Microcapsules were attracted to the gate of a pH-sensitive field effect transistor by a permanent magnetic field to form a bioreceptor on its surface. The immobilization technique used required no chemical reagents to activate and regenerate transistor's surface. The volume of the measured sample was 3 I; the total reaction volume, 30 mu l. Biosensor signals developed over a time of the order of 30-150 s. The biosensor enabled the detection of urea within the concentration range of 0.03 up to 100 mM. The enzyme activity and signal values of the biosensor did not decrease within 30 days. Measurements of real blood samples yielded a satisfactory correlation of biosensor data and clinical data (correlation coefficient, 0.78). (C) 2015 Elsevier Ltd. All rights reserved.

Systematic experimental and computational studies of the energy efficiency of continuous-detonation combustors (CDCs) have been performed. A small-size and a large-size CDCs using hydrogen as fuel and oxygen or air as oxidizer have been developed and tested. It was first experimentally proved that the Zel’dovich thermodynamic cycle with continuous-detonation combustion of a hydrogen-oxygen mixture in an annular combustor is more efficient than the Brayton thermodynamic cycle with continuous combustion of the mixture, other things being equal. The specific impulse of a small-size bench-scale rocket engine with a 50 mm diameter CDC operating in the continuous-detonation mode was 6–7% higher than that in the continuous combustion mode of operation. The measured fuel-based specific impulse for the large-size CDC of 406 mm diameter running on a hydrogen-air mixture was at a level of 3000 s. Three-dimensional calculations to optimize the structure and operation mode of the large-size CDC have shown that when running on a combustible mixture with a nearly stoichiometric overall composition, the specific impulse can be increased to ≈4200 s.

A biosensor is proposed based on a pH-sensitive field-effect transistor for detecting urea. The bioreceptors are polyelectrolyte microcapsules (size of 3–4 μm) with encapsulated paramagnetic particles of Fe3O4 and enzyme urease, capable of biotransforming urea. The bioreceptor was formed on the surface of a transistor gate using a constant magnetic field; the sedimentation of microcapsules in the gate zone proceeded because of the presence of paramagnetic particles in the bioreceptor. The microcapsules were prepared separately and stored at 4°C. This method of biosensor formation took several seconds and did not require additional chemical reagents for treating the electrode surface before and after the measurement. The lower limit of the detection of urea was 0.03 mM in the range of 0.03–100 mM. The biosensor is characterized by high sensitivity (~3.58 pH/mM) and time of signal formation of about 30–150 s, depending on the concentration of urea. The biosensor was tested on milk samples.

The idea of the combustion chamber with a continuous detonation was proposed by B.V. Voitsekhovskii in 1959 [1]. One of possible con¦gurations of the continuous detonation combustor (CDC) is an annular channel formed by the walls of the two coaxial cylinders. If the bottom of the annular channel is equipped with an injector head and the other end of the channel is equipped with a nozzle, one obtains the annular jet engine. Detonative combustion in such a chamber can be arranged by starting a supply of fuel mixture through the injector head, producing a single ignition pulse for detonation initiation, and burning fuel mixture supplied through the injector head in a detonation wave (DW) continuously circulating above the chamber bottom. The DW will burn the fuel mixture newly arrived in the CDC during one revolution of the wave around the circumference of the annular channel. The rotation frequency of the DW(s) in the CDC is determined by the mean diameter of the annular gap, the mean propagation velocity of the wave, and the number of waves simultaneously rotating above the bottom. For example, in the CDC with the mean diameter of the annular gap 300 mm operating with one or two DWs propagating at 1700 m/s, the rotation

Combustion chamber with a continuous detonation was ¦rst studied by Voitsekhovskii in 1959 [1]. One of possible con¦gurations of the continuous detonation combustor (CDC) is an annular channel formed by the walls of the two coaxial cylinders. If the bottom of the annular channel is equipped with an injector head and the other end of the channel is equipped with a nozzle, one obtains the annular jet engine. Detonative combustion in such a chamber can be arranged by starting a supply of fuel mixture through the injector head, producing a single ignition pulse for detonation initiation, and burning fuel mixture supplied through the injector head in a detonation wave continuously circulating above the chamber bottom. The detonation wave will burn the fuel mixture newly arrived in the CDC during one revolution of the wave around the circumference of the annular channel. The rotation frequency of the detonation waves in the CDC is determined by the mean diameter of the annular gap, the mean propagation velocity of the wave, and the number of waves simultaneously rotating above the bottom. The main advantages of such combustors include better propulsion performance due to pressure gain combustion [2], quasi-steady out§ow of detonation

A three-dimensional numerical simulation of the operation of an annular rotating-detonation chamber (RDC) with separate supply of combustible mixture components, hydrogen and air, is performed, and the calculation results are compared to available experimental data. The model is based on a system of time-dependent Reynolds-averaged Navier-Stokes equations complemented with a turbulence model and continuity and energy equations for a multicomponent reacting gas mixture. The system is solved using a coupled algorithm based on the finite volume method and particle method. Calculations are for the first time performed with allowance for effects of finite rates of turbulent and molecular mixing of the combustible mixture components with each other and with reaction and detonation products. The calculation results compare favorably with the experimental data obtained at the Lavrentyev Institute of Hydrodynamics of the Siberian Branch of the Russian Academy of Sciences.

The aim of this work is to apply three-dimensional numerical simulation to determining the conditions of the stable operation of the rotating-detonation chamber (RDC), the thermal state of the chamber walls, as well as the most important parameters of the flow at the inlet and outlet, keeping in mind the possibility of placing the RDC between a compressor and a turbine in a prospective gas turbine installation. The model is based on a system of three-dimensional unsteady Reynolds-averaged Navier-Stokes, energy, and species conservation equations for a multicomponent reacting gas mixture supplemented by a turbulence model. The system is solved using a combined algorithm based on the finite-volume and particle methods. The capabilities of the computer program are demonstrated by the example of a circular RDC with inner and outer walls 260 and 306 mm in diameter and with axial introduction of a hydrogen-air mixture through an annular gap at the bottom of the chamber (with a relative area of 0.6). The detonation wave spun over the bottom at a frequency of ∼126000 rpm. Calculations have shown that such an RDC can operate in a steady mode with one detonation wave.

We present results of experiments on the action of nanosecond pulsed beams of nitrogen ions and nitrogen plasma on specimens of Ti-4 Al-3 V (wt %) alloy that were obtained using a plasma focus device. Two regimes of material treatment were studied: a high-energy irradiation (with radiation power density of 108 W/cm2), where the surface layer is melted, and a softer irradiation regime (with radiation power density of 107 W/cm2), where a liquid phase on the surface is not formed. The mechanisms of surface modification and hardening of Ti-4 Al-3 V alloy corresponding to different irradiation regimes are discussed.