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The optical techniques (particle image velocimetry (PIV), laser-induced phosphorescence (LIP), planar laser-induced fluorescence (PLIF)) are used to study unsteady and inhomogeneous temperature and velocity fields of a gas–vapor mixture forming in the immediate vicinity of rapidly evaporating water droplets. Experiments involve various arrangements of several (two, three, and five) water droplets in a heated air flow. We establish the dependencies of the temperature and velocity of a gas–vapor mixture in the trace of each droplet on the heating time, velocity and temperature of the air flow, initial dimensions, and droplet arrangement scheme. Distinctive features of the synergistic effect of a droplet group on their temperature and aerodynamic traces are identified. Longitudinal and transversal dimensions of the aerodynamic and thermal traces of evaporating droplets are established. The length of the temperature trace of one droplet equals 10–12 of its radii, and the width of the temperature and aerodynamic trace of a droplet is no larger than its diameter. [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 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]

The hot plasma formed onto the surface of nanostructured targets by a relativistically intense (up to 4 × 10 W/cm), high contrast femtosecond laser radiation is studied. The nanoscale structures (pores, spheres, grass) were produced via laser ablation or chemical etching of bulk silicon and molybdenum. We report one of the first experimentally observed manifold enhancements of gamma yield at the background of hot electron energy growth from 200 to >600 keV, compared to the case of initially flat substrate in the relativistic regime of interaction. The efficiency of hot particle production is significantly affected by the shape of the structures. Experimental results are supported by 2D3V Particle-In-Cell simulations of laser-plasma interaction. It is shown that a laser-based plasma source, formed onto the surface of a solid target may be utilized for phase contrast X-ray imaging in a wide energy range of photons. [ABSTRACT FROM AUTHOR]