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A complex computer model of thermomechanical phenomena and a technique for end-to-end modeling of processes occurring in a solid material under the action of an intense energy flux are developed. Using the example of calculating the impact on a polymer material, the dynamics of nonlinear wave processes leading to internal damage in a sample of the material and spalling phenomena are discussed. The created software can be used in the analysis of the results of intense energy impacts in engineering practice, verification of models of volumetric fractures, and spallation in brittle materials, as well as validation of wide-range equations of state. [ABSTRACT FROM AUTHOR]

Objective: to determine the association of catalase С-262Т gene polymorphism with the presence of bronchial hyper-reactivity in children living in radioactively contaminated territories. Materials and methods. There were examined school-age children-residents of radioactively contaminated territories (RCT), who did not have clinical signs of respiratory pathology. Catalase (CAT) С-262Т gene deletion polymorphism was studied in the molecular genetic laboratory of the State Institution «Reference Center for Molecular Diagnostic of Public Health Ministry of Ukraine». Determination of the polymorphic variant by the catalase С-262Т gene was performed by Polymerase Chain Reaction (PCR) using specific oligonucleotide primers, followed by Restriction Fragment Length Polymorphism (RFLP) analysis. The CAT С-262Т gene polymorphism in children living in RCT was compared with that in the reference group of practically healthy individuals. Ventilation lung capacity was performed by computer spirometry according to the analysis of the loop «the flow-volume». A pharmacological inhalation test with a bronchodilator that acts on β2-adrenergic receptors of the lungs was used to detect early changes in the ventilatory capacity of the lungs - bronchial hyperreactivity. Results. Comparative analysis showed that in the presence of bronchial hyperreactivity in children living in RCT, the CT genotype was more common than in children without bronchial hyperreactivity, and the frequency of the CC genotype was correspondingly reduced. There was a trend towards a decrease in the frequency of the TT genotype. An analysis of the frequency distribution of allelic variants of the CAT С-262Т gene polymorphism in children living in the RCT revealed a tendency to increase in the frequency of the T-allele and according to the decrease in the frequency of C-allele in the presence of bronchial hyperreactivity. Сonclusions. Thus, among children living in RCT, CT-homozygotes of CAT С-262Т gene polymorphism had bronchial hyperreactivity probably more often than CC-heterozygotes. In the presence of bronchial hyperreactivity, there was a trend towards an increase in the frequency of the T-allele and, accordingly, a decrease in the frequency of the C-allele. [ABSTRACT FROM AUTHOR]

According to the calculation data, the penetrating action of shaped charges can be substantially increased (by 40–50% in the case of a target made of high-strength steel) if the lower velocity threshold, at which the termination of the penetration of the tail sections of a shaped-charge jet into the target occurs, is decreased by increasing the accuracy of their fabrication. To experimentally confirm these data, it is proposed to study in detail the penetration capability of the tail sections of shaped-charge jets with the use of cut-off rods made of a material with a high density which are positioned at a short distance from the shaped charge (of less than its diameter) and are intended for eliminating the higher-velocity portion of the jet. The possible parameters of the cut-off rods for obtaining isolated "tails" of shaped-charge jets with different velocities of the leading element are predicted based on the numerical modeling within a two-dimensional axially symmetrical problem of continuum mechanics. [ABSTRACT FROM AUTHOR]

A single-phase physico-mathematical model of a high-speed waterjet forming process that uses the underwater abrasive waterjet cutting technology while an abrasive-liquid flow under a pressure ranging from 60 to 80 MPa passes through the jet-forming path of a mobile abrasive waterjet machine has been developed. The results of a numerical experiment are presented. It has been shown that the main structural parameters of the internal profile of the jet-forming element (the profile of the focusing cavity, diameter and length of the output-channel) influence the geometric and kinematic parameters of the formed jet and the consumption of the hydro-abrasive suspension. [ABSTRACT FROM AUTHOR]

We present here a review of the literature analyzing the link between the physiological mechanisms of cold adaptation and cold-induced prooxidant and compensatory antioxidant processes. Cold adaptation has been shown to increase the number and activity of mitochondria to support increases in ATP consumption; this leads to increased generation of reactive oxygen species (ROS), as mitochondria are among the main sources of ROS in physiological conditions. Studies in recent decades have shown that protein PGC-1α – one of the main regulators of mitochondrial biogenesis – also affects the synthesis of antioxidant enzymes, thus controlling the mitochondrial generation of reactive oxygen species. At the whole-body level, systematic cold stimulates intrinsic protective resources by enhancing oxidative processes, which in turn initiates activation of the antioxidant systems and increases the overall resistance of the body to stress factors of different types. [ABSTRACT FROM AUTHOR]

Test calculations of the motion and reflection of individual waves in a long tube have been performed applying newly developed and known schemes with a floating grid. Waves in the corresponding experiment were formed using a specially designed single-cycle generator. The version presented is shown to have a significant advantage in calculation time over the discontinuity decay method, in which the computational grid density must be increased significantly to obtain the desired correspondence with the real wave pattern. [ABSTRACT FROM AUTHOR]

We substantiate the recommendations for improving the efficiency of hydro- and hydroabrasive cutting of the honeycomb structures that are widely used in aircraft and rockets, obtained by numerical solving of the spatial dynamic problem with allowance for the physico-mechanical and kinematic parameters of a high-speed jet, the physico-mechanical and structural parameters of the treated honeycomb structure, and the parameters of the technological treatment (feeding and the impact angle of the jet with the face surface of the blanks). A physico-mathematical model and a method of numerical analysis of the process have been developed. The influence of the above parameters on the quality of the surfaces of the treated blanks is illustrated. The results of the calculations are compared with the experimental data. [ABSTRACT FROM AUTHOR]

This paper analyzes detonation processes in an explosive laser device, in particular the indirect radiation of an explosive material. A hydrodynamic approach is applied to the numerical analysis, the results of which are in good agreement with experimental data. [ABSTRACT FROM AUTHOR]

The laser initiation of PETN is studied using the hydrodynamic approximation. The calculated and measured values of the threshold energy fluence for the laser initiation of PETN are compared. [ABSTRACT FROM AUTHOR]

This paper presents a simulation of the slow (laminar) combustion (deflagration)-to-detonation transition in a mixture of hydrogen and oxygen for two cases: case 1 - the mixture contains no inhibitor, its composition varies depending on the stoichiometric relation, and case 2 - the stoichiometric mixture contains an inhibitor CBrF, its concentration is varied. In the investigation, we solved the equations of combustion gas dynamics obtained on the basis of primary notions "combustion surface" and "flame velocity." In the first case, the distance and time of transition to detonation increase rapidly with deviation from the stoichiometric composition of the hydrogen-oxygen mixture. The same is also observed in the second case with increasing inhibitor concentration. Transition to detonation is possible until the inhibitor concentration reaches its limiting value at which laminar combustion is impossible. [ABSTRACT FROM AUTHOR]

The mathematical model of a high-speed collision between bodies with arbitrary elongation and massive metallic obstacles has been suggested. The model is based on the energy balance and stage-by-stage scheme of formation of a crater. The collision process has been considered to be the quasi-stationary penetration of the deformed impactor and inertial deepening of a crater at the final step. A comparison of the calculations with the results of numerical simulations and physical experiment has shown satisfactory agreement. [ABSTRACT FROM AUTHOR]

The calculation model of the impact indenting electrode interaction with an AMg6 aluminum alloy plate on the electrodynamic treatment of weld joints is described. The problem was solved in the Lagrange two-dimensional statement with an ANSYS/LS-DYNA program. Calculation results for residual stress and plastic strain regions formed on the elastoplastic indenting electrode impact are presented. [ABSTRACT FROM AUTHOR]

We consider the physicomathematical formulation of the problem of explosive formation of a penetrator from a low-sphericity copper lining. Calculations are made for the formation of a penetrator for a phlegmatized hexogen charge for two models of the behavior of the lining material (copper), and the results are compared with the experimental data. [ABSTRACT FROM AUTHOR]

In developing the numerical large-particle method, new calculation schemes providing for analytical determination of the parameters using the ambiguity principle and the transition to the second order of accuracy in time and space are presented. Furthermore, the change in the density at the Eulerian stage of the method is taken into account. As a result, the stability of the computing procedure of complex flows with separations and free jets is provided at the values of the difference Courant number close to unity. This circumstance makes it possible to reduce considerably the time of calculations and to increase their accuracy. [ABSTRACT FROM AUTHOR]

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Objective is to study the role of еNOS gene polymorphism in the development of endothelial dysfunction and functional disorders of the respiratory system in children - residents of radioactively contaminated areas. Materials and methods. Total of 184 children were examined to determine the possible associative links between еNOS gene intron 4m polymorphism and indices characterizing the functional state of the endothelium and the bronchopulmonary system. Of them the main group of children consisted of 135 children-residents of radioactively contaminated areas, the control group - of 49 healthy children who lived in "clean" regions by the radioactive contamination and were not belonging to victims of the Chernobyl accident contingents. The molecular genetic study determining the еNOS gene intron 4 polymorphism was performed. An examination of lung ventilation capacity was evaluated using the pneumotachography method. The thermographic method was used for registering the endothelium dependent reaction of the vascular bed to changes in blood supply conditions. The levels of nitrogen compounds (NO2and NO3-) were determined by the standard method using Hriss reagent. The level of body incorporated 137Cs was determined using human radiation counter Skrynner 3M (Institute of Human Ecology). Results. Children of the main group did not differ from that of control and literature data by the frequency of genotypes 4a/b and еNOS gene allele polymorphism. An increase in the duration of circulation restoration up to the initial level after occlusion test was noted in children of the main group with genotype 4a/4b comparing to children with genotype 4b/4b; a decrease in the nitrite content was observed in blood serum. The integral indices of elasticity and tensility of the lung tissue, respiratory permeability were decreased; the signs of bronchospasm were recorded 1.5 times more often. These adverse effects were associated with the presence of genotype allele 4a, the signs of endothelial dysfunction and the level of the incorporated 137Cs. Conclusions. More pronounced changes in vascular endothelial reaction to occlusion and the significant decrease of serum nitrite level in allele 4a carriers, especially in children who live in adverse ecological conditions, give the right to include them into the risk group for the development of endothelial dysfunction, and to conside pulmonary dysfunction as one of its manifestations. [ABSTRACT FROM AUTHOR]

The physicomathematical problem of the explosive formation of a cumulative knife (jet) from a cumulative charge and its penetration into a 250-mm-thick armed concrete obstacle is considered. Numerical simulation data for a specific extended cumulative charge acting against this obstacle at different focal lengths of the charge are presented. [ABSTRACT FROM AUTHOR]

The formation of high-velocity compact elements of shaped charges with a liner of a combined hemisphere-cylinder shape has been analyzed by numerical simulations of a two-dimensional axisymmetric problem of continuum mechanics. The influence of the radius and thickness of the hemispherical portion of the combined liner on the parameters of the compact elements has been studied. It is shown that in implosion of hemispherical liners whose thickness decreases from top to bottom, there is an increase in the velocity of the resulting jet flow. When using a hemispherical portion of variable thickness (to increase the velocity of the compact elements formed), it is necessary to solve two additional problems-to implement timely separation of the head part of the jet flow with increased velocity and increase its mass. For this, it is proposed to use the jet-forming part of the combined liner in the form of a truncated sphere or a slightly elongated ellipsoid of revolution. Combined shaped-charge liners in the form of a truncated ellipsoid of variable thickness were developed, allowing the formation of compact elements having a velocity of 7.5-10 km/s. [ABSTRACT FROM AUTHOR]

The local crystallization during annealing at 600 °C in nanoscale diamond-like carbon coatings films grown by pulsed vacuum-arc deposition method was observed using modern techniques of high-resolution transmission electron microscopy. The crystallites formed by annealing have a face-centred cubic crystal structure and grow in the direction [0ĪĪ] as a normal to the film surface. The number and size of the crystallites depend on the initial values of the intrinsic stresses before annealing, which in turn depend on the conditions of film growth. The sizes of crystallites are 10 nm for films with initial compressive stresses of 3 GPa and 17 nm for films with initial compressive stresses of 12 GPa. Areas of local crystallization arising during annealing have a structure different from the graphite. Additionally, the investigation results of the structure of nanoscale diamond-like carbon coatings films using Raman spectroscopy method are presented, which are consistent with the transmission electron microscopy research results. [ABSTRACT FROM AUTHOR]

Computational and experimental techniques to determine the dynamics of nondeformable or slightly deformable striker penetration into soil obstacles are presented. One of the computational procedures is based on using empirical relationships for finding mechanical stresses on the striker-obstacle contact surface; the other, on the numerical simulation of penetration in terms of the 2D axisymmetric problem of continuum mechanics. In experiments, the striker dynamics is analyzed with piezoelectric accelerometry data. These procedures are applied to study the penetration of a striker into plastilina, which is used to model low-strength media like clay ground. From experimental data, parameters are obtained that characterize the physicomechanical properties of a plastilina target and are used in the computational techniques. Verification of the computational techniques is made. [ABSTRACT FROM AUTHOR]

Results of investigations into the properties of nanosized carbon coatings doped with nitrogen, tungsten, and aluminium and obtained on silicon by the pulse vacuum arc method are discussed. The doping effect on internal stress values, microhardness, and surface morphology was studied. It has been established that doping nanosized carbon coatings with nitrogen, tungsten, and aluminium makes it possible affect their internal stress values, surface morphology, and the strength properties of the substrate-coating system. [ABSTRACT FROM AUTHOR]

The results of an experimental and theoretical study of the high-velocity (600–1000 m/s) interaction of impactors filled with Teflon with semiinfinite and finite-thickness titanium and aluminum targets are presented. The effects of the physicomechanical and physicochemical properties of the filler on the parameters of the caverns produced in targets of various thicknesses made of the indicated materials are assessed. [ABSTRACT FROM AUTHOR]

It has been postulated that the one-humped (Arabian) dromedary and the two-humped (Bactrian) camel originated from a single ancestor. Consequently, the dromedary was considered a breed of the two-humped camel, based on an anatomical study by Lombardini L, 1879: Ann. Del. Universita Toscane, 259, 147, who described a reduced second hump like structure in foetal and adult dromedaries. To resolve this lingering issue, we analysed dromedary foetuses and calves. In contrast to the situation in two-humped camels, we never observed any rudimentary second hump in the dromedary foetuses or calves. [ABSTRACT FROM AUTHOR]