Vol 54, No 1 (2016)

Ultrashort laser pulses have enabled highly precise and delicate processing of biological specimens. We present the results of using femtosecond laser pulses for dissection of zona pellucida (ZP) in mouse embryos during assisted hatching procedure. We studied the effects of application of femtosecond laser radiation in the infrared (1028 nm) and visible (514 nm) wavelength ranges. Laser irradiation parameters were optimized so as not to compromise the viability of the treated embryos. We have demonstrated that application of femtosecond laser pulses with the energies in the range of 250–320 nJ (for the wavelength of 1028 nm) and 47–112 nJ (for 514 nm) resulted in efficient ZP dissection. Femtosecond laser-assisted ZP drilling does not slow down the development of pre-implantation embryos and leads to 90–95% frequency of complete hatching. The thermal effects can be significantly lower when femtosecond lasers are used as compared to continuous wave or long-pulse lasers. It is crucial when dealing with living cells or organisms. By optimizing femtosecond laser radiation parameters assisted hatching as well as a wide range of embryo-surgical procedures can be efficiently performed, thus creating a great potential of using femtosecond lasers as a multi-purpose “tool of choice” for specialists in the fields of embryology and developmental biology.

A drift of Li⁺ ions upon electric interactions in a planar channel formed by graphene sheets and a cell separated by two graphene membranes with pores of various types has been investigated by the molecular dynamics method. The optimal size of the planar channel gap is determined based on the character of the ion dynamics and the ion effect on the physical properties of the graphene sheets. A set of graphene sheets with divacancies demonstrates the best throughput of lithium ions among six sets of membrane pairs. The ions passing through the membrane are found to affect the kinetic characteristics of the graphene membranes.

Heat transfer to water-cooled surfaces of metals and quartz is studied experimentally in subsonic jets of dissociated carbon dioxide at a stagnation pressure of 80 hPa and enthalpy of 9 and 14 MJ/kg, corresponding to the descent conditions of the ExoMars space vehicle into the Martian atmosphere, using an RF induction plasmatron at the Institute for Problems in Mechanics, Russian Academy of Sciences. The measurements of heat fluxes to surfaces of different materials showed the significant effect of the catalytic properties of surfaces that can be arranged in the following descending order of the heat flux: silver, copper, stainless steel, quartz. The effect of strong modification of the silver surface is recorded during the tests; the maximum value of the heat flux is achieved after 15-min exposure of the surface to the jet. In the computational analysis of heat transfer, we used a two-parameter model of heterogeneous recombination of O atoms and CO molecules at the surface. With this model, the effective recombination coefficient of CO molecules is determined on the water-cooled surfaces of quartz and stainless steel, based on the experimental data on heat fluxes.

We present the results of experimental study of the electric discharge between metal electrodes of various geometry and technical water within the pressure range of 8 × 10³–10⁵ Pa at the saw-tooth voltage generator frequency, f = 40 MHz, and the interelectrode distance, l = 3–30 mm. We consider transfer of the streamer discharge into spark one depending on the geometry of the metal electrode and its material. We investigate the electrical characteristics of the discharge between the plate electrode and the technical water within a wide pressure range. The essential influence of the streamer discharge type on the ozone release within the investigated parameters range is discovered.

The data (the speed of sound, the isobaric and isochoric heat capacities, as well as the heat capacity ratio) for liquid neon presented in the NIST Chemistry WebBook are analyzed. It has been shown, based on the representation of the inverse reduced volume fluctuations, that they consist of sufficient discrepancies in the subcritical region. The correction of data in this region of the coexistence curve is evaluated using the fluctuation approach and the theory of thermodynamic similarity.

The change in the spatial distribution of relative temperatures in the system of a spherical particle located in the center of a spherical matrix is simulated. Silicon nitride (Si₃N₄) and boron nitride (BN) are considered in a matrix of potassium bromide (KBr); graphite, diamond, and silicon nitride are studied in a copper matrix. Calculations are performed for the four sizes of particles: 1, 5, 20, and 100 μm. It is shown that the temperature is equalized by approximately 80% in 1 μs in the particles of Si₃N₄ and BN with a size of 5 μm in the KBr matrix. In the system of silicon nitride–copper, such alignment is performed for a particle with a diameter of 20 μm. For a diamond particle in the copper matrix, the particle size may be even greater. The particle sizes for which calculations showed a rather high rate of heat transfer in a time of ~1 μs either match or are somewhat larger than the particles of diamond, cubic boron nitride, and γ-silicon nitride formed during the real shock-wave synthesis of these materials.

We present the experimental results on the solubility of supercritical carbon dioxide in polyethylene glycol of molecular weight 4000, namely, the isotherms at T = 313, 323, and 333 K in the pressure range of P = 10–35 MPa. Based on the Sanchez–Lacombe lattice model, the results of solubility are described and the empirical parameters of the binary intermolecular interaction in the system of supercritical CO₂-polyethylene glycol 4000 are obtained.

Linear and nonlinear relations, which make it possible to determine the rate of heat flux in the mode of film boiling on a cylindrical heating surface, have been obtained by transforming the system of moment conservation equations derived from the Boltzmann kinetic equation based on the four-term approximation in the form of a two-sided Maxwellian. For this problem and the interaction potential of Maxwell molecules, the Boltzmann kinetic equation is solved by the moment method in elaboration of the approach of L. Lees and C.-Y. Liu to the description of thermal conductivity through a gas-filled cylindrical gap between two impermeable interfaces. The obtained analytical expressions for the heat flux can be used at any values of the Knudsen number determined from the cylindrical heater radius.

The results of numerical modeling of the ignition process of hydrogen–oxygen mixtures diluted with argon at temperatures of 700–2500 K within wide ranges of the initial gas parameters are presented. The time evolutions of the concentration of the electron-excited radical OH* and other components, as well as the strength of the radical total radiation on wavelengths about λ = 306.4 nm, are calculated. Their peculiarities are described and the correspondence between the measured radiation strength scans obtained in the experiments by the emission method and those calculated in the process of modeling is determined. The temperatures upon which the mixtures ignite are determined. The dependences of the time delay of the ignition of the mixture on the pressure and component composition are found. The relationships are used to obtain the temperature dependence of the ignition time delay reduced to a preliminarily chosen pressure and gas composition.

A promising new way of direct conversion of the heat of piston engine exhaust gases into electric energy is investigated. An original design of a thermoelectric converter with various surface reliefs (smooth, spherical peaks, spherical dimples) is developed. The engine operation and the flow in the heat-exchanger of the thermoelectric generator are modeled. Based on the results of 3D modeling of convective heat transfer, it has been determined that the surface with heat transfer intensifiers in the form of spherical dimples is the most efficient.

In developing technologies of ultrafast (within 5 min) electric vehicle charging, problems occur related to the power supply. The charging station, an analog of a refueling station, should have an extremely irregular load with a high peak power. It might be located far from the possible point of connection to the power grid and should represent an object of decentralized power generation by means of an electrical energy storage system. We consider and compare an autonomous gas-turbine facility and a lead-acid battery as the possible power supply. We found an averaged statistically optimal relation between the gas turbine power (or the contracted power) and the battery capacity providing for minimum expenses, reduced to the service life, for creation and exploitation of the station of ultrafast charging of a given number of electric vehicles per day.

We have tested the neutral, against the sorption material, gas (nitrogen) in the RKhO-8 metal hydride reactor containing 1 kg of the LaNi_4.8Mn_0.3Fe_0.1 alloy and have calculated the viscous permeability coefficient: k = 0.42 ± 0.08 μm².

The experimental results on stability of the relative elongation of isostatic isotropic GIP-4 graphite under cyclic thermal loads within the temperature range of 1240–2270 K are presented.

A method for determining the energy of the interparticle repulsion between ions is proposed based on a comparison of the experimental data for gas molecules and crystals of these substances. The available experimental data on the compressibility of the compounds with a crystal lattice of the NaCl type in the solid state are examined, and the repulsion energy is determined for a number of substances for which there are no data on their compressibility.

This study continues previous publications devoted to kinetic processes in nonequilibrium hydrogen plasma. This review contains an analysis of the kinetics of hydrogen molecules in the ground state and in excited singlet electron states in various gas discharges. The distribution functions measured over the vibrational levels of a hydrogen molecule in the ground electron state are compared with those calculated within the developed level semiempirical collisional-radiative model of low-temperature hydrogen plasma. A database of the measured and calculated collisional-radiative characteristics of kinetic processes involving excited hydrogen molecules and the parameters of low-temperature hydrogen plasma is formed.