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Specific features of the pyridine structure make it a convenient model system to describe coal combustion; however, the main attention of researchers has been paid to the formation of the ortho-pyridyl, whereas the formation of meta- and para-pyridyls has been yet poorly studied. The rate constants of the formation of three pyridine radicals by hydrogen atom abstraction by another hydrogen atom are compared. The geometry of the reactants is optimized within the framework of the density functional theory with subsequent refinement of single-point energies by the ab initio G3(MP2,CC) hybrid method. The calculations show that the formation of ortho-pyridyl is preferable, though the formation and further transformations of all three radicals should be taken into account for a detailed description of the coal combustion process.

This paper describes a numerical simulation of a laminar flame of a premixed mixture of ethanol and air at atmospheric pressure with the addition of a suspension of ethanol droplets. The initial fuel-oxidizer ratio in the gas phase is ϕ_gas = 0.844 and 1.125. With account for the fuel in the liquid phase, the total equivalence ratio is ϕ_tot = 1.195 and 1.476, respectively. The calculation is performed using the method of direct numerical simulation with a reduced chemical mechanism. Motion, heating, and evaporation of droplets are determined using the Lagrange approximation. The numerical simulation results are verified using experimental data (flame cone photographs and laser-induced fluorescence data). It is revealed that all the droplets evaporate in the flame front heating region and the presence of fuel in the liquid phase significant increases the CO concentration both in the calculation and in the experiment.

A numerical and experimental study of concentrations of combustion products and pollutant emissions in the case of combustion of premixed methane-hydrogen mixtures in a model combustion chamber of a gas-turbine power plant is performed. The mathematical model of combustion of methane--hydrogen mixtures used in the study ensures good qualitative and quantitative agreement between the numerical and experimental data on the main combustion products and also qualitative agreement on emissions of pollutants. In what follows, this mathematical model of combustion combined with the chosen kinetic mechanism of combustion can be used to analyze the emission characteristics of gas-turbine power plant combustion chambers designed for operation on hydrogen-containing mixtures.

The possibility of solving problems of chemical kinetics using artificial neural networks is investigated. The main laboriousness of solving problems of chemical kinetics lies in solving a rigid system of balance equations, whose right side contains the component mass production intensity. This problem can be singled out as a separate stage of solving a system of ordinary differential equations within a common time step of the global problem, and this stage is considered in this paper. A fairly simple model is developed that can solve this problem, which makes it possible to achieve a threefold acceleration of calculations as compared to numerical methods. The resulting neural network operates recursively and can predict the behavior of a chemical multicomponent dynamic system many steps ahead.

The geometric structures, vibration frequencies and relative energies of reactants, products, intermediates, and transients involved in the self-recombination of the indenyl radical were determined using G3(MP2,CC) // B3LYP/6-311G^** quantum chemical calculations. The barrierless association of a pair of indenyl radicals forms the C₁₈H₁₄ complex. The subsequent set of isomerizations of the complex is divided into five reaction channels, which in all cases end in H abstraction but with different four-ring isomers C₁₈H₁₄: in the form of condensed rings-tetraphene, tetracene, chrysene, dibenzoazulene; with an associated internal bond of the rings-dibenzofulvalene. The yield of chrysene prevails since the energy barriers encountered on the pathway of its formation are lower than the barriers on the formation pathways of other products.

Stability of a swirl flame of a premixed methane-air mixture under various gravity conditions is studied. Charts of stable combustion at normal and reverse gravity in the coordinates of the flow velocity and equivalence ratio. It is shown that the limits of stable combustion remain unchanged regardless of using a swirler with and without the central body, but the flame geometries are different. Swirlers are found to produce a minor effect on the flame blowout conditions, especially under the normal gravity condition. It is demonstrated that a swirler allows obtaining a rich lifted flame under the normal gravity condition and a lean lifted flame under the reverse gravity condition. It is found that dilution of the mixture with the fuel leads to expansion of the boundary of combustion stability under the reverse gravity condition as compared to the situation under the normal gravity condition.

The authors appraise application of milky quartz from the Larino lode deposit in production of high-purity quartz concentrate with the total content of impurities less than 50 ppm. The structure and texture of milk quartz are analyzed using the optical microscopy and ICP-OES spectrometry methods. The elemental analysis data of the preconcentration and deep concentration products are compared. The low contents of the impurity elements in the deep concentration products of quartz from most lodes of the Larino deposit prove the applicability of this quartz material as a feedstock for the production of high-purity quartz concentrates.

The authors discuss feasibility of high-tonnage direct inclusion of overburden in composites for the construction of road layers at mines. It is found that overburden has a strength as per State Standard GOST 23558-94 and the prolonged dedusting effect. The optimal contents of the binder and fly ash are 8 and 10% by mass, respectively. Mechanical activation of fly ash for 1 min enlarges its specific surface by 2 times. The frost-resistant composites modified with mechanically activated fly ash and stabilizer (1% by mass) have the strength grades M20-M40.

The scope of overburden investigation embraces overburden volume, physical state, mineralogy and chemistry, content of toxic elements, hydraulic/thermal/physical/mechanical properties, compositional analysis and potential process flows with a view to manufacturing materials of construction. It is found that the mineral and chemical compositions of overburden in coal mining are the same as the mineral raw material has, and the content of toxic elements is within the allowable concentrations. These rocks are classified as modulus-active and highly active, and are thermally inert. The integrated processing of overburden in coal mining enables using these rocks as a feedstock for the production of heat-insulating, ceramic, binding and road construction materials.

Tripolium genus is represented by the only species Tripolium pannonicum (Jacq.) Dobrocz. The individuals of this species feature variable morphological characters due to wide distribution area of the species covering vast territory from the Atlantic coast of Europe through the Pacific Ocean. As a typical halophyte, it grows in azonal communities of several latitude zones. The study was based on the analysis of morphological characters which used to be diagnostic in distinguishing between the closely related taxa: T. pannonicum (Jacq.) Dobrocz. subsp. tripolium (L.) Greuter. (T. vulgare s. str.) and T. pannonicum (Jacq.) Dobrocz. subsp. pannonicum. The significance of morphological diagnostic characters in protologs and subsequent botanical literature is discussed. Such morphological characters as presence/absence of heterocarpy and stem branching pattern are stated to be independent of geographical distribution of populations. They rather represent an adaptive character of propagation in annual plants of Tripolium pannonicum (Jacq.) Dobrocz. under variable environmental conditions of under flooding zone.