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We investigated the chemical beam epitaxy of GaP 1 − x N x grown on nominally (001) -oriented Si substrates, as desired for the lattice-matched integration of optoelectronic devices with the standard Si technology. The growth mode and the chemical, morphological, and structural properties of samples prepared using different growth temperatures and N precursor fluxes were analyzed by several techniques. Our results show that, up to x ≈ 0.04 , it is possible to synthesize smooth and chemically homogeneous GaP 1 − x N x layers with a high structural quality. As the flux of the N precursor is increased at a given temperature to enhance N incorporation, the quality of the layers degrades upon exceeding a temperature-dependent threshold; above this threshold, the growing layer experiences a growth mode transition from 2D to 3D after reaching a critical thickness of a few nm. Following that transition, the morphology and the chemical composition become modulated along the [ 110 ] direction with a period of several tens of nm. The surface morphology is then characterized by the formation of { 113 } -faceted wires, while the N concentration is enhanced at the troughs formed in between adjacent (113) and (1 ¯ 1 ¯ 3). On the basis of this study, we conclude on the feasibility of fabricating homogeneous thick GaP 1 − x N x layers lattice matched to Si (x = 0.021) or even with N content up to x = 0.04. The possibility of exceeding a N mole fraction of 0.04 without inducing coupled morphological–compositional modulations has also been demonstrated when the layer thickness is kept below the critical value for the 2D–3D growth mode transition. [ABSTRACT FROM AUTHOR]

The paper shows the effect of introducing Lactiplantibacillus plantarum AG10 biomass into quail feed. Quails that received a probiotic feed additive for seven weeks demonstrated a significant improvement in such economic indicators as the dynamics of live weight, the mass of gutted carcasses and feed consumption per kg of gain. Using the analysis of 16S rRNA gene sequence libraries sequenced on the Illumina MiSeq platform, shifts in the microbiota of the cecum have been detected, which may contribute to improving the morphological and physiological parameters of quails. [ABSTRACT FROM AUTHOR]

Tandemly arranged repetitive regions (repeats) that encode 5S rRNA (5S rDNA) are an indispensable component of eukaryotic genomes. Typically, 5S rDNA repeats within a genome are very similar due to the concerted nature of the evolution of this type of repeats. Each 5S rDNA repeat consists of an evolutionarily conserved coding sequence (CDS) and a variable intergenic spacer (IGS). 5S rDNA is a popular model for studying the molecular evolution of repetitive sequences, and the high rate of IGS mutations determines its wide use in phylogenetic analysis of closely related taxa. Nevertheless, 5S rDNA remains unexplored for many groups of higher plants, especially for the Plumbaginaceae family. Some taxa of this family are endemic to southern Ukraine and listed in the Red Book. However, their taxonomic status is controversial, and its clarification requires the use of molecular phylogenetic methods. In this work, we examined the molecular organization of 5S rDNA for representatives of four genera of the tribe Limonieae, the largest in the family Plumbaginaceae. It was shown that the CDS of 5S rDNA of representatives of the genera Limonium, Armeria, and Ceratolimon possess single mutations that do not affect the formation of the secondary structure of 5S rRNA. In contrast, in the genomes of Goniolimon species, in addition to functionally normal 5S rDNA repeats, numerous pseudogenes were found that do not evolve in a concerted manner and contain numerous mutations in the CDS that disrupt the secondary structure of 5S rRNA. A significant phylogenetic distance between representatives of the subgenera Pteroclados and Limonium of the genus Limonium indicates that Pteroclados can be considered a separate genus. The high rate of molecular evolution makes 5S rDNA IGS a convenient tool for the reconstruction of phylogenetic relationships within the studied genera of the tribe Limonieae and the barcoding of Ukrainian endemics of the genus Limonium. [ABSTRACT FROM AUTHOR]

The genus Muscari Mill. (Asparagaceae Juss.) includes about 80 species distributed in Eurasia, mainly in the Mediterranean region. Recent molecular phylogenetic studies have shown that the taxa belonging to this group form a monophyletic clade and are closely related. However, the phylogeny and status of some taxa of Muscari sensu lato remain controversial. So far, most phylogenetic studies of the genus Muscari have used almost exclusively Mediterranean plant material, while representatives of the genus from the Carpathian region remain unexplored. In this work, we used the sequencing of three regions of chloroplast DNA, psbA-trnH, trnT-L, and trnL-F, to clarify the phylogenetic relationships in the genus Muscari, to assess the genetic polymorphism and taxonomic status of Ukrainian populations of M. botryoides, as well as specimens of other Muscari species from the Carpathian region. According to the results of the phylogenetic analysis, the genus Muscari is a monophyletic group that includes three subgenera: Muscari, Muscarimia, and Pseudomuscari. Leopoldia species have been placed in the subgenus Muscari. Specimens of M. botryoides from Ukraine and Austria together with M. transsilvanicum from Romania and M. serpentinicum/M. sandrasicum from Turkey form the clade "Botryoides", one of the three main clades identified in the subgenus Muscari. A significant genetic distance between Ukrainian specimens of M. botryoides, specimens of this species from other habitats, and other species of the genus Muscari allows us to consider the Ukrainian specimens of M. botryoides as a new, previously undescribed species. A comparison of the sequences of the investigated regions of the chloroplast genome revealed genetic differences between two groups of Ukrainian populations of M. botryoides, which can be interpreted as the existence of two intraspecific forms. [ABSTRACT FROM AUTHOR]

Compact laboratory neutron sources play a crucial role in both fundamental physical research and practical applications, such as neutron radiography and spectroscopy. One of the most promising strategies to develop such a source is the use of laser-plasma accelerators of electrons or ions and the subsequent initiation of nuclear reactions (γ,n), (p,n), or (d,n) with the release of neutrons. In this study, we propose a neutron source based on (γ,n) photodisintegration reactions and characterize it using an electron beam from a 1‑TW laser-plasma accelerator. The maximum neutron flux reaches ~105 neutrons/s srad at a laser-radiation efficiency of ~106 neutrons/J. While maintaining efficiency and increasing the energy of the laser pulse by a factor of 10, the neutron flux becomes sufficient for several applications. To investigate neutron production using electron beam parameters measured in experiments, we conduct numerical Monte Carlo simulations. Recording the number of neutrons generated in an experiment can be used to estimate the charge and average energy of accelerated electrons. The simulation results show good agreement with values measured by standard beam-diagnostic tools, confirming the accuracy of our approach. [ABSTRACT FROM AUTHOR]

Revealing the regularities of interaction of accelerated ions with an irradiated material based on the Monte Carlo simulation contributes to the efficient application of focused ion beam technique in modern nanotechnologies. The correctness of the calculation results depends on the model chosen and the parameters determining the surface binding energy (SBE) of sputtered atoms. In this work, the SBE has been determined within the discrete–continuous model, which makes it possible to consider the formation of gallium precipitates during irradiation of a silicon substrate with gallium ions. To compare the simulation results with the experimental data on material sputtering by a focused ion beam, two types of rectangular boxes have been prepared. The structures of the first type were formed at the same dose, close to 5 × 1017 cm–2 (corresponding to the steady-state sputtering regime), at accelerating voltages of 8, 16, and 30 kV. The structures of the second type were formed at an ion energy of 30 keV and doses of 2.5 × 1016, 5 × 1016, and 1 × 1017 cm–2. The box cross sections were investigated by transmission electron microscopy. The sputtering yield and depth distribution profiles of gallium atoms, calculated in the SDTrimSP 5.07 software package, were compared with the experimental data using the R factor. Two sets of values have been established for the variable parameters: the SBE of gallium atoms and the α1 parameter of the discrete–continuous model. The first set describes the experimental data with acceptable accuracy for a small number of implanted gallium atoms, which is implemented for low ion doses, as well as for a beam energy of 8 keV and a dose of 5 × 1017 cm–2. The second set is optimal for describing the ion beam interaction with the substrate at ion energies of 16 and 30 keV under steady sputtering conditions. [ABSTRACT FROM AUTHOR]

The methods of transmission electron microscopy and high-resolution electron microscopy, used to study multilayer heterocomposites, have limitations in resolution, do not allow for the effective investigation of amorphous materials and require the analysis of many local areas in the case of samples consisting of individual crystallites. In this work, we investigate a multilayer heterocomposite, which is a phase-shift photomask consisting of layers of nanoscale thickness on the surface of a glass substrate. Focused-ion-beam methods are used to study a thin foil of cross and longitudinal sections. To identify the structure and determine the composition of the layers, the methods of transmission electron microscopy and energy-dispersive X-ray microanalysis are used. The analysis of cross-sectional foils prepared using standard approaches allows visualization, thickness measurements, and determination of the layer compositions. It is shown that on the SiO2 substrate an amorphous layer of Mo0.06Si0.31N0.63 93 nm thick is formed, which is successively coated with polycrystalline layers of Cr0.56N0.44, Cr0.74C0.06N0.2, and Cr0.4N0.26O0.3 with thicknesses of 22, 37, and 8 nm, respectively. A thin foil with a planar cross-section, prepared at a slight inclination to the surface of the photomask, makes it possible to form sections of all layers with dimensions sufficient for their study by electron microdiffraction. The performed electrographic analysis confirmed the amorphous structure of the substrate and Mo0.06Si0.31N0.63 layer, and also showed that polycrystalline layers of Cr0.56N0.44, Cr0.74C0.06N0.2, and Cr0.4N0.26O0.3 formed by crystallites with a cubic lattice and parameters of 3.92, 4.18, and 4.12 Å, respectively. [ABSTRACT FROM AUTHOR]

The precision fabrication of microstructures and nanostructures by the focused-ion-beam method is significantly simplified by the simulation of sputtering of materials by accelerated ions. A widely used approach to such simulation is the Monte Carlo method, which, to be correctly used, requires data on the surface binding energy of sample atoms. In this study, to obtain data on the surface binding energy for silicon carbide, test structures in the form of rectangular areas sputtered using gallium ions with a dose of 1017 cm–2 are fabricated. Their cross sections are studied by transmission electron microscopy and energy-dispersive X‑ray microanalysis. The average gallium concentration in the vicinity of its maximum is found to be = 25 at %. This value and a sputtering yield of Yexp = 2.1 are used for comparison with the results of calculation in the SDTrimSP 5.07 software package using the R factor. The comparison is made using available continuous and discrete models and the proposed discrete-continuous model for calculating the surface binding energy. The best agreement between the calculated and experimental data is obtained with the discrete-continuous model, which yields = 30 at % and Y = 2.57, as well as the physically adequate values of the surface binding energy, by varying two fitting parameters. The efficiency of the discrete-continuous model is due to the fact that it takes into account the weak chemical interaction of sample atoms and the ion beam atoms and the formation of implanted gallium precipitates in irradiated silicon carbide. [ABSTRACT FROM AUTHOR]

The genus Aconitum L. includes many species of toxic and pharmaceutically important plants. One of the centers of diversity of this genus is located on the territory of the Eastern Carpathians. Many representatives of this genus from the region frequently have unclear taxonomic status, such as members of the A. anthora s. l. complex. The taxonomic position of this complex within the genus also remains controversial since the chloroplast and nuclear genomic regions used for a phylogenetic analysis proved to be insufficiently variable. Therefore, the search for some optimal molecular marker with a high level of polymorphism within the genus Aconitum is urgent. The 5S rDNA intergenic spacer (IGS) is an evolutionarily variable region of the nuclear genome that was successfully used earlier for the phylogenic reconstruction in many groups of angiosperms. In this study, 5S rDNA IGS sequences for the members of the A. anthora complex and the phylogenetically distant Aconitum species were obtained using molecular and bioinformatics methods. The analysis of IGS sequences has shown that this region in species of this genus is relatively long, ranging in length from 574 to 619 bp. The IGS variability is explained by numerous nucleotide substitutions, whereas short oligonucleotide indels occur only at the 5'-end of the spacer. The IGS of Aconitum species harbors four conserved regions with two of them corresponding to the external elements of the RNA polymerase III promoter and terminator, whereas the function of the other two remains unknown. The first of them demonstrates homology with the 5S rRNA coding region, whereas the second has a high level of similarity to the genomic sequences of taxonomically distant families of monocots and dicots, which may be due to presumptive horizontal gene transfer. The phylogenetic analysis with the use of the 5S rDNA IGS confirms the treatment of A. anthora s. l. as a separate subgenus within the genus Aconitum. [ABSTRACT FROM AUTHOR]

The cutting of special stainless steels for thrust bearings is studied experimentally. The steels considered are 95Х18-Ш, 110Х18-ШД, 75ХГСФ, and 40ХНЮ-ВИ. The formation of the surface roughness and the distortion of the part after machining are described. The influence of the cutting parameters on the cutting force and temperature in the machining zone is determined. Experiments are conducted to determine the roughness of the machined surface and the distortion of the samples in various cutting conditions. The results provide the basis for technological recommendations. [ABSTRACT FROM AUTHOR]

The results of an experimental study of the integral evaporation characteristics of water droplets that are present in the composition of an aerosol cloud are described. Parameters, such as the initial radius of the droplets (0.1–0.25 mm), their concentration (0.03–0.1 L/m3), and the temperature of combustion products (573–873 K), are varied. The ranges of variation of the weight rate of water evaporation as function of the concentration of droplets in the aerosol cloud and their initial sizes are established. Approximation expressions for the established dependences are obtained. An approach is proposed for determining the rate of evaporation of aerosol droplets, which takes into account the known values of the evaporation rate of a single droplet. [ABSTRACT FROM AUTHOR]

The natural distribution area of the western honey bee, Apis mellifera L., covers Europe, West Asia and Africa. Adaptation to local environmental conditions resulted in the formation of numerous subspecies and ecotypes of western honey bee, which represent a convenient model for studying the microevolution of insects. Genomic region encoding 5S rRNA (5S rDNA) is a popular tool for investigation of the molecular evolution and phylogeny of closely related animal and plant taxa. In this article, we present the results of the analysis of 5S rDNA polymorphism in two breeding races, Rakhiv and Hoverla, of the Carpathian breed of western honey bee, which represents the local ecotype of the subspecies A. m. carnica, and compare them with the data available in the Genbank database for this subspecies and the Asian species A. cerana. It was found that in the genome of A. m. carnica there are at least two classes of 5S rDNA, each of which includes several structural variants. The genomes of the two studied races of the Carpathian breed and that of the A. m. carnica from Genbank differ in the sets of such variants, while the 5S rDNA repeated units of the of A. cerana are identical within the genome. The obtained results indicate a high intra- and intergenomic polymorphism of 5S rDNA in A. m. carnica. [ABSTRACT FROM AUTHOR]

The efficient injection of electrons into a propagating relativistic laser pulse with normalized vector potential a0 ∼ 2 is demonstrated numerically and experimentally in a thin plasma layer with density 0.15–0.3 of the critical value. The injection is due to the wavebreaking of parametric plasma waves. The trapped particles gain multi-MeV (up to 20 MeV) energies by the direct laser acceleration in the plasma channel formed by the laser pulse in the lower density plasma tail. Numerical calculations were supported by experiments with micron-scale films pre-evaporated by an additional nanosecond laser pulse and a TW femtosecond laser facility. The experimentally observed bunch of electrons with energy above 1.6 MeV had a divergence of ∼0.05 rad and charge of ∼50 pC measured with photoneutron Be(g,n) reaction. [ABSTRACT FROM AUTHOR]

The wavy hair-grass, Avenella flexuosa (L.) Drejer (also known as Deschampsia flexuosa (L.) Trin. or Lerchenfeldia flexuosa (L.) Schur), is a species of perennial herbaceous plant of the Poaceae family that is widespread in Eurasia, Africa, North and South America. Whether this species belongs to the Deschampsia genus has long been an open question. Taking into account that the 5S rDNA comparison is a convenient tool in the molecular taxonomy of plants, we cloned and sequenced this region of the A. flexuosa genome and evaluated the genetic distances between this species and other species of the Poeae tribe. It has been found that at least two structural classes of 5S rDNA repeats are present in the A. flexuosa genome. The spacer regions in the 5S rDNA of A. flexuosa and D. antarctica have a low level of similarity that does not exceed the level of similarity with representatives of several other genera of the Poeae tribe. The 5S rDNA clones of A. flexuosa and D. antarctica form two distinct clades on the phyllodendogram. Taking together, our results support the idea that A. flexuosa belongs to a separate genus Avenella. [ABSTRACT FROM AUTHOR]

The tool wear and microcrack formation in the machining of medium-carbon bearing steels are studied experimentally for the example of ШХ15-ШД and 75ХГСФ steels. Numerous features of the wear of polyhedral single-use inserts with a wear-resistant coating are noted. Different behavior is observed for the two types of bearing steel. To determine the roughness of the machined surface, its dependence on the machining conditions—the cutting speed, supply, and cutting depth—is studied experimentally. The experimental data permit practical recommendations. [ABSTRACT FROM AUTHOR]

The results of experiments on the localization and complete cessation of flame combustion and thermal decomposition of typical forest combustible materials (for example, pine needles and birch leaves) are presented, using a specialized control line before the combustion front in the form of a moistened layer of material with control of its size and retained water volume. Necessary and sufficient conditions for the complete cessation of flame propagation and the pyrolysis front are determined. The relationships between the main parameters are established: the volume of water, the density and intensity of irrigation, the size of the control water strip, and the volume of dry forest combustible material. When summarizing the experimental results, the values of the rational density and intensity of irrigation of forest combustible material before the combustion front are highlighted. The main differences in the selection of the effective values of these parameters are shown in the case of localization and cessation of flame burning and thermal decomposition of needles and leaves. [ABSTRACT FROM AUTHOR]

Results of an experimental study of heat and mass transfer and phase transitions during suppression of flaming combustion and thermal decomposition of condensed matter (CM) by an example of typical combustible materials in the forest (mixtures of leaves, conifer needles, and twigs) by means of the action of a non-atomized water array at different stages of its transformations are reported. The liquid volume and the height of its discharging with respect to the CM surface are varied with allowance for the known stages of water array transformations to illustrate possible differences in the cross-sectional areas of these arrays, which determine the water–CM contact area. The characteristics of CM burning termination are obtained as functions of the height of the beginning of water array motion. [ABSTRACT FROM AUTHOR]

Metallic nanoparticles are promising objects of study, since their properties greatly differ from the properties of bulk material. In analyzing nanoparticles, it is important to investigate their size, stability, structural features, and spatial arrangement. In this study, initial and annealed silver nanoparticles from ∼2 to 10 nm in size formed on a carbon substrate by vacuum thermal evaporation are investigated by high resolution transmission electron microscopy and their shape and structure are classified. The examined nanoparticle types include faceted ellipsoid ones with a polycrystalline structure, coarse ones with a single-crystal structure and twins, icosahedral and decahedral ones with multiple twinning, and fine single-crystal nanoparticles smaller than 3.5 nm. It is established that, after annealing, the total number of nanoparticles decreases by a factor of ~1.3, the number of fine nanoparticles almost halves, and the fraction of nanoparticles with icosahedral and decahedral cross sections increases by a factor of ~1.5. It is shown that nanoparticles smaller than 5 nm become unstable already after a few seconds of exposure to high-energy electrons. For fine single-crystal nanoparticles smaller than 3.5 nm, the average crystal-lattice parameter is found by precise determination of the centers of atomic columns in their images and calculation of the local distances between atoms located in the mutually perpendicular (200) and (022) planes. It is shown that, in such nanoparticles both before and after annealing, there are no noticeable crystal-structure distortions and their lattice parameter is similar to the value characteristic of bulk silver. [ABSTRACT FROM AUTHOR]

The genus Quercus (oak) is a widespread and economically important genus of tree plants. The intrageneric taxonomy of this group remains controversial due to widely distributed interspecific hybridization and convergent similarity of morphological traits. Further progress in this problem requires application of molecular methods. Taking into account that the comparison of 5S rDNA was successfully used in the molecular taxonomy of plants, we cloned and sequenced this genomic region for representatives of three taxo-nomically distant Quercus species: Q. acutissima (sect. Cerris) and Q. glauca (sect. Cyclobalanopsis) from East Asia and Q. texana (sect. Lobatae) from North America. We also identified 5S rDNA in the genome sequences available in the Genbank database for North American species Q. lobata (sect. Quercus) and for the related genus Castanea. It was found that the 5S rDNA repeated units demonstrate a high level of intragenomic sequence similarity in representatives of genus Quercus. The potential external elements of the 5S rDNA promoter differ from those in other families of dicotyledonous plants. The results of the comparative sequence analysis of the 5S rDNA intergenic spacer region support the existing taxonomy of the genus and indicate the isolated position of section Cyclobalanopsis, which can be considered as a separate subgenus. [ABSTRACT FROM AUTHOR]

Results of experimental investigations on the suppression of the flame combustion and thermal decomposition of forest combustible materials by aerosol flows of a pure water and aqueous solutions are presented. The characteristics of some sprayers were determined and the densities of wetting of a fire hotbed, provided by them, were calculated. The times of extinguishing hotbeds of model crown and ground forest fi res were measured, and distributions of temperatures and heat flows in them were determined. It is shown that the efficiency of extinguishing a forest fire is mainly determined by the sizes of the aerosol droplets acting on it. [ABSTRACT FROM AUTHOR]

Processes involved in the collision of liquid droplets enhance their atomization. If droplets contain more than one component, these processes become especially strong and intense. In this paper, we describe experiments for heterogeneous droplets of water solutions, emulsions, and slurries typical of fuel, firefighting, and heat and mass transfer technologies. We determine the conditions for a stable occurrence of the four droplet collision regimes: bounce, coalescence, separation, and disruption. We go on to establish how droplet dimensions, velocities, impact angles, component concentrations, as well as liquid viscosity, surface tension, and density affect collision parameters. The experimental results are generalized using collision regime maps produced in the coordinate systems controlling for the variations of Weber, Reynolds, Ohnesorge, and capillary numbers, as well as angular and linear interaction parameters. The results are compared with the scarce data by other authors. The Weber number variation range is not the only factor influencing the droplet collision behavior the form of four interaction regimes. Viscosity and surface tension of the liquid have a significant impact as well. An increase in the viscous forces can provide conditions for droplet breakup into a maximum number of small fragments. Coalescence is the dominating mode at low viscosity and high surface tension. Droplet bounce occurrence does not only depend on the Weber number range but also on phase transformations and thermophysical properties of the liquid. Finally, we determine the droplets interaction parameters for group of liquids that can provide intense droplet atomization through collisions. [ABSTRACT FROM AUTHOR]

At the present time, the uncontrolled interbreeding of bees that belong to different subspecies or races of Apis mellifera has become a threat in Ukraine. Conserving the gene pool of local bee breeds, which are well adapted to the local environmental conditions, is an urgent problem that cannot be solved without the application of molecular methods for monitoring of the genetic composition of local populations. To clarify the origin of the Carpathian bee and to develop molecular methods for its identification, sequencing and comparative analysis of the CoI–CoII region of the mitochondrial genome of the Carpathian bee and representatives of several subspecies of A. mellifera was performed. In the studied region, a mutation specific for the Carpathian bee was discovered. It was found that Carpathian bee originates from the Central European subspecies A. m. carnica and represents the ecotype that arose from the migration of this subspecies to the East, which resulted in the formation of Carpathian populations of honey bees. [ABSTRACT FROM AUTHOR]

We have experimentally studied the influence of solid impurity particles present in aqueous aerosol droplets on their interference patterns. The interference patterns were studied with the aid of a Nd:YAG laser and CCD video camera. The radii of droplets in the aqueous aerosol ranged within 10–140 μm. Solid particles of four materials were introduced in the aerosol to a mass concentration of 0.003–1 g/L. Specific types of interference patterns determined by the presence of solid impurities in droplets are described, and the influence of impurity type and concentration on the integral characteristics of these patterns (number and type of images) is established. A new approach to determining the impurity concentration and particle dimensions in aerosols is proposed based on the analysis of their interference patterns. [ABSTRACT FROM AUTHOR]

Generation of terahertz radiation upon filamentation in air of two-color radiation in loose focusing conditions with focal lengths from 30 to 312 cm and a beam diameter of 0.8 cm was studied. Two-color radiation was generated in a nonlinear BBO crystal irradiated by a converging laser beam. Measurements show that the energy input into the medium increases dramatically with a decrease in the focal length to 50 cm or less; at F = 30 cm, the energy of a terahertz pulse linearly depends on the laser pulse energy and increases significantly at F = 50 cm. Terahertz radiation is still not observed at longer focal lengths, which is apparently due to a spatio—temporal mismatch of the radiation of the first and second harmonics. [ABSTRACT FROM AUTHOR]

The conditions and characteristics of intensive evaporation of very inhomogeneous drops of emulsions of water with petroleum products (gasoline, kerosene, residual oil, heavy crude, transformer oil, turbine oil) were experimentally investigated at relative volume concentrations of these products in emulsions varying in the wide range from 10 to 70% corresponding to a large number of high-temperature (1100 K) processes occurring with gas and vapor drops, such as the heat and flame purifications of water and the production of a synthetic gas from fuel emulsions and suspensions based on water. The conditions of explosion breakdown of emulsion drops in the process of their heating have been determined. Three regimes of breakdown of emulsion drops, differing in the number of small droplets formed and in their surface area, were separated. Proposals were made on the mechanisms of the physical processes leading to the transformation of the surface of emulsion drops and their explosion breakdown. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study of the initiation and containment of the flaming combustion and thermal decomposition of typical forest fuels by creating a fire break in the form of a wet layer of fixed width, length, and depth with a known volume of contained liquid. The ranges of parameter values that ensure stable suppression of the flaming combustion and thermal decomposition of forest fuel material were determined Experiments were performed for all major types of forest fuels: leaves, needles, branches, and mixtures thereof. The minimum water volumes and fire-break sizes required for guaranteed containment of combustion of the investigated forest fuels are predicted. [ABSTRACT FROM AUTHOR]

Experimental investigations into the high-temperature (700 to 1200 K) heating, evaporation, ebullition, and subsequent disintegration (breakup) of droplets of water emulsions (with a volume concentration of petroleum products to 70%) have been performed using high-speed video recording. Consideration has been given to the emulsions based on water, oil, mazut, kerosene, and industrial oil. A study has been made of two schemes of supply of energy to the droplet: local heating due to the contact with a heated metallic rod with variation in the cross section of its tip and evaporation on a massive heated substrate, i.e., a steel platelet of diameter 50 mm and thickness 5 mm. From the results of an analysis of the frames of videograms illustrating different schemes of implementation of the investigated processes of transformation of the surface of the emulsion droplet and of its heating, evaporation, filling with vapor bubbles, ebullition, and breakup, the authors have established the influence of basic factors (temperature and surface area of heating, concentration of the components, droplet dimensions, and properties of petroleum products) on the time of full evaporation of the emulsion droplet. Distinctive features of the processes of evaporation and ebullition of emulsion droplets in high-temperature superheating have been determined. The authors have singled out different regimes of heating of the droplets, which differ not only by the time of full evaporation but also by the effects (preservation of a monolithic state, explosive disintegration accompanied by the formation of a fine aerosol, and ignition of the emulsion). [ABSTRACT FROM AUTHOR]

Abstract: In the present paper, we established the conditions and the main characteristics of the stable boiling and subsequent explosive disintegration of emulsion droplets based on water and oil products under high-temperature (from 350 to 1100 K) heating using high-speed video recording (up to 105 frames per second). The studies were carried out under various conditions of energy supply to the droplet: on a massive substrate, in contact with a heated rod (local heating), and in a heated air flow. The times of heating up the emulsion droplets before the explosive decay are determined. The scale of the effect of the ambient temperature (up to 1100 K), the heat flux density (up to 104 kW/m2), and the oil product concentration (up to 70%) in the emulsion on these characteristics is established. Using high-speed video tracking, the main characteristics of the emulsion droplet decay are determined: the duration, surface transformation stages, and the number of liquid fragments formed (up to 300) and their total area (7-8 times higher than the initial one). The conditions for the emulsion drop decay both before and after its ignition were studied. [ABSTRACT FROM AUTHOR]

Abstract: Deschampsіa antarctіca, one of the two angiosperm species growing in the extreme conditions of Antarctica, is a unique model for studying the relationship between genetic polymorphism and such factors of evolution as isolation, migration and adaptation to new environmental conditions. Molecular markers represent a useful tool for the investigation of these questions. To examine the potential of 5S rDNA to be used for the discrimination of D. antarctica populations we cloned and sequenced this genomic region for plants from three populations of this species from Maritime Antarctica. It was shown that in the genome of D. antarctica at least two structural classes of 5S rDNA are present, which differ by numerous base substitutions and insertions/deletions in the intergenic spacer. Based on this structural polymorphism we propose to apply this region for the evaluation of the intraspecific genetic diversity of D. antarctica. [ABSTRACT FROM AUTHOR]

Deschampsia antarctica, one of the two angiosperm species growing in the extreme conditions of Antarctica, provides a unique model for studying the relationship between genetic polymorphism and such factors of evolution as isolation, migration and adaptation to new environmental conditions. Molecular markers represent a useful tool for the investigation of these questions. To examine the potential of 5S rDNA to be used for the discrimination of D. antarctica populations we cloned and sequenced this genomic region for plants from three populations of this species from Maritime Antarctica. It was shown that in the genome of D. antarctica at least two structural classes of 5S rDNA are present, which differ by numerous base substitutions and insertions/ deletions in the intergenic spacer. Based on this structural polymorphism we propose to apply this region for the evaluation of the intraspecific genetic diversity of D. antarctica. [ABSTRACT FROM AUTHOR]

An experimental study has been performed to investigate the integral characteristics of the processes of heat and mass transfer and phase transformations during interaction of a droplet flow with the combustion front of a highly porous condensed material. The macroscopic regularities of the suppression of flaming combustion and thermal decomposition of typical forest fuel material due to the removal of heat as a result of its absorption during vaporization and convective cooling were studied. Three modes of interaction of a droplet aerosol with the burning forest fuel materials were considered. The time of combustion termination and the time of thermal decomposition of forest fuel materials were determined. The mechanisms of the main physicochemical processes occurring during interaction of droplet flow with the combustion front of typical forest fuel materials were established. [ABSTRACT FROM AUTHOR]

Experimental investigations on determination of the volume of water with different additives, necessary for the effective suppression of the flaming combustion and thermal decomposition of typical forest combustible materials (birch leaves, pine needles, aspen twigs, and a mixture of these materials), have been performed. It was established that the addition of a penetrating, a fire retarding, or a fire-extinguishing admixture to a water aerosol substantially changes its fire-extinguishing properties and that the sizes of a hotbed of fire influence the destruction of the forest combustible materials in it. The necessary intensity of spraying of fire-extinguishing liquids of different compositions over a fire hotbed was determined. [ABSTRACT FROM AUTHOR]

An experimental investigation of the physiochemical processes occurring in the localization of a ground forest fire by spraying of water over its edge has been performed. Several schemes of formation of a barrage, comprising a moistened forest combustible material and an aerosol curtain, for such a fire are presented. It is proposed to spray water in the region upstream of the combustion front, in the region of the combustion front, and simultaneously in these regions. The conditions of extinguishing of a model ground forest fire by spraying of water over its edge were determined depending on the velocity of movement of the combustion front, the density of spraying of the fire hotbed, the dispersivity of the water used for the spraying, and the width of the fire barrage. The times of termination of the movement of the front of flame combustion of a forest combustible material, complete burn-out of this material, and cessation of its thermal decompositions in the case of formation of a fire barrage around it were estimated. The parameters of the spraying of water over the edge of a ground forest fire, providing its localization and suppression, were determined. [ABSTRACT FROM AUTHOR]

The processes of redeposited and crystalline silicon sputtering under focused Ga ion-beam irradiation are simulated using the Monte Carlo method and different models of the surface binding energy of Si and Ga atoms. The sputtering yields and the profiles of the distribution of Ga atoms in the sample, calculated for different ion energies, are compared with the experimental data. It is established that the introduced model of the surface binding energy of Si and Ga atoms, taking into account the formation of Ga precipitates in the near-surface region of the sample, makes it possible to reach the best agreement with the experimental data. [ABSTRACT FROM AUTHOR]

The structure of carbon nanopillars grown without catalysis by low-temperature plasmaenhanced-chemical-vapor deposition on a silicon substrate is investigated using the suggested focused ion beam technique for preparing a sample composed of several thin plan-view foils. Studying the prepared sample by electron diffraction and bright-field transmission electron microscopy allows determination of the variation of the two-dimensionally ordered crystallite fraction along the growth direction. It us established that the crystalline phase fraction inside the nanopillars gradually decreases during the growth process. Nearly 90% of the crystalline material is located between the base and the middle of the nanopillars while their upper parts almost entirely consist of amorphous carbon. [ABSTRACT FROM AUTHOR]

Experimental investigations on the characteristic time of suppression of the thermal decomposition reaction of typical forest combustible materials (aspen twigs, birch leaves, spruce needles, pine chips, and a mixture of these materials) and the volume of water required for this purpose have been performed for model fire hotbeds of different areas: SFCM = 0.0003-0.007 m2 and SFCM = 0.045-0.245 m2. In the experiments, aerosol water flows with droplets of size 0.01-0.25 mm were used for the spraying of model fire hotbeds, and the density of spraying was 0.02 L/(m2·s). It was established that the characteristics of suppression of a fire by an aerosol water flow are mainly determined by the sizes of the droplets in this flow. Prognostic estimates of changes in the dispersivity of a droplet cloud, formed from large (as large as 0.5 L) "drops" (water agglomerates) thrown down from a height, have been made. It is shown that these changes can influence the conditions and characteristics of suppression of a forest fire. Dependences, allowing one to forecast the characteristics of suppression of the thermal decomposition of forest combustible materials with the use of large water agglomerates thrown down from an aircraft and aerosol clouds formed from these agglomerates in the process of their movement to the earth, are presented. [ABSTRACT FROM AUTHOR]

This paper presents the experimental studies of the deceleration, reversal, and entrainment of water droplets sprayed in counter current flow to a rising stream of high-temperature (1100 K) combustion gases. The initial droplets velocities 0.5-2.5 m/s, radii 10-230 μm, relative volume concentrations 0.2·10-1.8·10 (m of water)/(m of gas) vary in the ranges corresponding to promising high-temperature (over 1000 K) gas-vapor-droplet applications (for example, polydisperse fire extinguishing using water mist, fog, or appropriate water vapor-droplet veils, thermal or flame treatment of liquids in the flow of combustion products or high-temperature air; creating coolants based on flue gas, vapor and water droplets; unfreezing of granular media and processing of the drossed surfaces of thermal-power equipment; ignition of liquid and slurry fuel droplets). A hardware-software cross-correlation complex, high-speed (up to 10 fps) video recording tools, panoramic optical techniques (Particle Image Velocimetry, Particle Tracking Velocimetry, Interferometric Particle Imagine, Shadow Photography), and the Tema Automotive software with the function of continuous monitoring have been applied to examine the characteristics of the processes under study. The scale of the influence of initial droplets concentration in the gas flow on the conditions and features of their entrainment by high-temperature gases has been specified. The dependencies Re = f(Re) and Re' = f(Re) have been obtained to predict the characteristics of the deceleration of droplets by gases at different droplets concentrations. [ABSTRACT FROM AUTHOR]

Multigenic families are widely represented in the genomes of higher plants, and are required for the reliability of cellular functions. Damage of individual genes can be compensated by diverse metabolic alterations, but the exact mechanisms of such compensations still remain not fully understood. Here we present novel data regarding the mechanisms of metabolic compensation in photorespiratory knock-out mutants cat2, cat3 and cat2cat3 of Arabidopsis thaliana, which are lacking activity of catalase isoforms CAT2 and CAT3. It was found that cultivation of the mutants under low light at optimal or increased temperature did not result in any morphological, physiological or biochemical signs of oxidative stress. Each of the mutant lines shows specific features of the compensatory mechanisms. Increased activity of CAT3 isoenzyme was found in the cat2 mutant, whereas cat3 and cat2cat3 demonstrate induction of CAT1, an isoform normally absent in young leaves, as well as activation of peroxidases, namely APX and POD. Comparison of these results and earlier published data revealed that the lack of CAT2 and CAT3 isoforms is compensated by preferential activation of non-enzymatic and enzymatic protection mechanisms, respectively. [ABSTRACT FROM AUTHOR]

The results of experimental investigations of the processes of water droplet evaporation upon heating in a gaseous medium at temperatures of 500–1100 K have been presented. High-speed tools of video recording and panoramic optical methods of particle image velocimetry have been applied. The times of full droplet evaporation and mass evaporation rates have been calculated. The evaporation rates have been compared with those calculated using well-known evaporation models. The temperature ranges in which the mathematical modeling data well correlate with experiments have been determined. [ABSTRACT FROM AUTHOR]

The fusion in air of four femtosecond laser beams each with the peak power several times higher than the critical self-focusing power has been studied experimentally. It has been shown that a superfilament formed in such a regime ensures the efficient energy input to a medium. It has been shown that the linear density of the input energy increases approximately quadratically with both the energy of a laser pulse and the number of fused beams. [ABSTRACT FROM AUTHOR]

The characteristic (longitudinal and transversal) dimensions and velocities of water and aqueous solution and suspension masses deformed in flight have been determined from the results of experimental studies for each transformation stage alongside with the conditions corresponding to interstage transitions. Using NaCl solutions and aqueous suspension with 100-500-μm carbon particles as an example, the effect of typical admixtures and inclusions (for chemical and power generation technologies, as well as in the sphere of safety at relative concentrations of up to 5 wt %) in water masses (initial volumes, 0.1-0.5 L) on the time of their transformation during free fall in air has been estimated. The distribution of the number of liquid fragments detached from the surface of a mass along the trajectory of its flight has been established. A hypothesis about the physics of decomposition processes observed in experiments due to the intensive deformations of water and aqueous solutions and suspensions has been formulated. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of heat and mass transfer and phase transformations in the suppression of flaming combustion and thermal decomposition of model ground, crown, and mixed forest fires due to local exposure to water. The experiments were carried out with typical combustible forest materials (mixture of leaves, needles, and twigs) and models of trunks and branches of trees. The conditions and characteristics of suppression of the flaming combustion and thermal decomposition of combustible forest materials were determined. It is shown that in the case of crown and mixed fires, local short-term (a few seconds) action of a liquid projectile does not suppress the thermal decomposition of the material (but can only lead to localization of flaming combustion). In the case of ground forest fires, this approach can be efficient with an appropriate choice of the water-irrigated area of the combustion zone and the rate and time of water spraying. [ABSTRACT FROM AUTHOR]