Home – Home – Jornals – Journal of Mining Sciences 2018 number 3

A numerical analysis of self-ignition of a hydrogen-air-water vapor mixture at different initial pressures is carried out. The results of this analysis are used to make a shortened list of reactions that make the largest contribution to the process rate during induction. A simplified analytical description of the system state before self-ignition, which makes it possible to calculate the thermal power and adiabatic heating rate of the system is presented. A method for estimating the autoignition limits from the adiabatic heating rate of the mixture is described.

The upper flammability limit of ethane-air and ethane-oxygen mixtures for various initial temperatures and pressures was determined experimentally. In experiments, the upper flammability limit increased with increasing initial temperature and pressure, which is consistent with literature data. The limit was determined in a closed vessel with central ignition. The obtained limit corresponds to quenching of the flame during its downward propagation after rise under the action of the Archimedes force.

Flame propagation in a closed vessel containing a stoichiometric propane-air mixture and partially filled with a porous medium was studied experimentally. The porous medium consisted of steel balls with a diameter of 3.2 and 6 mm and ceramic balls with a diameter of 6 mm. An experimental dependence of the maximum pressure during flame propagation in the vessel on the degree of filling of the vessel with the porous medium was obtained. Theoretical pressure estimates are made which are in satisfactory agreement with experimental data. The estimates closest to the data of the experiments are based on the assumption that the gas burns adiabatically in free space and is isothermally compressed in the porous medium. The influence of heat losses from the gas to the porous medium and the walls of the on the maximum pressure was analyzed.

A modified physicomathematical model of ignition of silane/hydrogen/air mixtures is applied to calculate the ignition delay time for these mixtures at low initial temperatures (300-900 K) and pressures (0.4-1 atm) of the mixture. It is shown that the diagrams of the ignition delay time as a function of temperature contains a region of the so-called negative temperature coefficient. The influence of the pressure in the mixture and of the silane fraction on the length of this region is studied. It is found that an increase in both factors (silane concentration and pressure in the mixture) leads to an increase in the length of the negative temperature coefficient region.

A physicomathematical model of the Rayleigh-Benard convection in a chemically equilibrium gas containing chemically inert microparticles (Al₂O₃) is proposed. A linear analysis of convection in the Boussinesq approximation is performed. It is shown that addition of chemically inert microparticles increases the critical value of the Rayleigh number and stability of the convective process. The possibility of using chemically inert microparticles for control and monitoring of convection in a chemically reacting gas is demonstrated by an example of a chemically equilibrium gas.

Single-phase aluminum diboride was obtained by thermal explosion of an aluminum-boron mixture mechanically activated in a planetary ball mill. It was established that the additional mechanical treatment of the products of thermal explosion made it possible to reduce the coherent scattering area size of AlB₂ to nanometer values. The results of X-ray phase and electron microscopy of the mechanocomposites and products of thermal explosion are presented.

The effect of a NiO additive on the combustion and structure formation in a Ni-Al-W system in self-propagating high-temperature synthesis (SHS) is under study. The stages of the combustion of compositions containing a NiO high-energy additive are shown. The interaction of W particles with Ni-Al melts during SHS results in the formation of globular decoration of particles on the basis of solid solutions of tungsten on the particle surface. This effect is observed only in compositions with an equimolar mixture of Ni-Al. Should the amount of 1 at. % be present in the original sample of the NiO additive, the globular decoration on the surface of unreacted W particles never occurs. This effect can be associated with changes in the combustion temperature, deviation of the NiAl phase in the direction of a larger content of Ni, and the influence of oxide phases on diffusion processes.

Owing to its high mass and volume heats of combustion, boron is a promising component of solid propellants for air-breathing engines. Its application is limited by difficulties of organizing high-efficiency combustion. Experimental investigations of combustion of individual boron particles demonstrate a large number of unique features, which are not typical for other materials: variable ignition temperature, two stages of combustion, and drastic reduction of the burning rate for particles with sizes of several micrometers or smaller. Models that cover the entire range of temperatures, concentrations, and particle sizes are physically non-obvious, can be hardly reproduced, and do not provide the accuracy needed for solving practical problems. In this paper, we propose a simple diffusion model of combustion, which ensures an adequate description of combustion of boron particles 34.5 and 44.2 μm in size at temperatures above 2240 K.

This paper describes a study of boron powders and powder compounds, obtained by various methods, including metallothermal, electrolytic, and boron hydride cracking methods. The crystal state, particle size and microstructure, presence and composition of impurities, and chemical composition of the oxide layer of boron particles are profoundly investigated. The effects of the above-mentioned characteristics on the particle oxidation parameters during heating with a constant velocity are analyzed. The determining influence of chemical composition of the particle surface layer on the initial temperature of their intense oxidation is established. It is shown that the maximum increase in the weight and heat release value during oxidation of the boron powders is almost independent of microstructural features, crystal state, and chemical composition of and oxide layer thickness of the particles, and cannot serve as indicators of completeness of boron oxidation during heating.

The heating of energetic materials by the radiation of fiber-coupled continuously-pumped lasers at near IR-wavelengths of 0.98, 1.56, and 1.94 μm was studied. Samples of pressed secondary explosives and loose gunpowder were used. The length of the linear portion of the temperature rise and the rate of its rise immediately after exposure to laser radiation were measured. It is established that the rate of temperature rise at the initial time is proportional to the laser radiation power aP. For a 600 μm diameter of the laser beam emerging from the fiber, the coefficient of proportionality a for secondary explosives was 6-250 K/(s × W) at a wavelength of 0.98 μm and 40-2000 K/(s × W) at wave lengths of 1.56 and 1.94 μm. For gunpowder, a = 7000-15000 K/(s × W), which is an order of magnitude or more higher than for most of the secondary explosives we studied. The possibility of increasing the efficiency of laser heating of secondary explosives by applying an absorbing thin film on the surface of the samples was studied. The heating dynamics and the initial stage of ignition of energetic materials by laser radiation were investigated.

Regimes of continuous detonation of methane/hydrogen-air mixtures in spin and opposing transverse detonation waves are obtained for the first time in a flow-type annular cylindrical combustor 503 mm in diameter. A two-component (methane/hydrogen) fuel with the H₂ mass fractions of 1/9-1/2 in the range of specific flow rates of the mixture from 64 to 1310 kg/(s × m²) and the fuel-to-air equivalence ratio φ = 0.78-1.56 is considered. In methane/hydrogen-air mixtures with two compositions of the fuel (CH₄ + H₂ and CH₄ + 4H₂) one-wave and two-wave regimes of continuous spin detonation are obtained; the frequency of rotation of transverse detonation waves is 0.56-1.66 kHz at φ = 0.78-1.02. For the fuel compositions CH₄ + 2H₂ and CH₄ + 1.5H₂, continuous multifront detonation with two opposing transverse detonation waves rotating with the frequency of 0.86-1.34 kHz at φ = 1.0-1.23 is obtained. For the CH₄ + H₂ + air mixture, both combustion in the chamber and continuous spin detonation outside the combustor with transverse detonation waves rotating with the frequency of 1.01-1.1 kHz are observed. The lean limits of continuous detonation are obtained in terms of the specific flow rate of the mixture: 64, 100, 200, and 790 kg/(s × m²) for the fuel compositions CH₄ + 8H₂, CH ₄ + 4H₂, CH₄ + 2H₂, and CH₄ + 1.5H₂, respectively, for the mass fraction of hydrogen in the methane/hydrogen fuel of ≈0.16. Violation of regularity of the continuous detonation wave structure and the wave velocity with a decrease in the fraction of hydrogen in the two-component fuel is detected.

A small-parameter equation of state in the Lie-Gruneisen form is proposed to describe shock compression of condensed matter. The equation is based on a postulated dependence of the Gruneisen coefficient on the specific volume and temperature Г(V,T), which provides a qualitative description of compression of metal samples in strong shock waves. The curve of cold compression is found on the basis of the dependence Г(V,T) with the use of a generalized formula for the Gruneisen function. Heat-induced oscillations of the crystal lattice are described in the Debye approximation. The resultant Gruneisen function has two free parameters. The values of other coefficients of the equation of state are determined from the reference data for the substances under standard conditions and also from the limiting values under extreme conditions. The model is tested by an example of copper. The derived equation of state describes the cold compression curve, normal isotherm, shock compressibility, as well as the copper unloading curves in density, pressure, and internal energy ranges for which experimental data are available. The thermodynamic characteristics of copper (isentropic modulus of volume compression, velocity of sound, Debye temperature, specific heat, linear expansion coefficient, and melting temperature) are calculated. Comparisons with available experimental data shows that the proposed model, despite its simplicity, ensures a consistent description of a large array of experimental data in the region of high energy densities.

The acceleration ability of an emulsion explosive sensitized with expancel polymer microballoons in the initial density range 0.193-1.2 g/cm³ was measured using the end acceleration method and the method of acceleration of a cylindrical shell. The results were compared with those obtained for 6ZhV ammonite and with the results of ANSYS AUTODYN simulation.

The effect of shell material (copper and silicon carbide) on the detonation of a cylindrical explosive charge was analyzed. The wave patterns in both the detonation products and the shells are substantially different, which is due to different sound velocities and the rapid destruction of ceramics under explosive loading. The wave pattern at the explosive/ceramic interface was found to have features associated with the desensitization of the explosive due to its loading by the leading wave from the shell side and manifested in a decrease in pressure, blurring of the detonation front, and an increase in mass velocity. Throughout the process, there is a continuous increase in the time of explosive decomposition near the interface of the explosive and the ceramic shell. An extended region with a constant pressure close to Chapman-Jouguet pressure was observed on the axis of symmetry behind the detonation front of the explosive charge in the ceramic shell.

The classical solution of elasticity problem on deformation of a plane weakened by a mathematical cut under wedging by constant forces is analyzed. The ill-posedness of the classical failure mechanics statements for problems with angular points is demonstrated. The approximate solution is constructed for deformation of continuum in the vicinity of a cut under small strains.

Rock is considered as a medium containing a load-bearing skeleton and a pore space. The two-dimensional closed deformation model under construction takes into account plastic strains and local bends of grains. The model describes the medium capacity to accumulate energy of internal self-balancing stresses.

A device is developed for loading granular materials by shearing with air flow driven through the material without its pseudo-liquefaction. Internal stresses and dilatancy of a sample are measured depending on shearing angle. It is shown that shear modulus, characterizing material capability to resist shearing as air flow rate is increased, lowers while dilatancy grows.

Interaction between an open-end pipe and a soil plug is studied using Coulomb’s law of friction. The scope of the study embraces different models of soil and pipe. The finite difference solutions obtained for all models and the analytical solutions derived for some models describe the elastic process of the pipe and soil interaction. Agreement of the numerical and analytical solutions is shown. Results of different model calculations are compared, and the validity limits are determined for the models. The influence of Coulomb friction on pipe and soil movement is investigated.

In order to ensure accurate hole-making in soil, it is required to adjust motion path of pneumatic puncher by deflecting its rear body relative to longitudinal axis. The structural layout of the path control mechanism, which allows upgrading series-production pneumatic punchers, is presented. The solution of problem on forces required to change the pneumatic punch path in soil is given. Soil body is considered as a rigid-plastic medium, and the deflector is assumed as a nondeformable body. The problem is solved in two stages: penetration of the deflector in soil and motion of the pneumatic puncher with the rear deflected at a certain angle in soil. The loads applied to the rear for changing pneumatic puncher path in soil and the turn radius under deflecting force are determined.

Two model approaches to estimation of lifetime of supporting mining machines are described, one of which is based on the theory of reliability and the other-on the principle of cost. While on service, reliability of machines reduces and operating cost grows. These indexes of opposite trends define machine serviceability, and make a framework for decision-making on the expediency of further operation, maintenance or replacement of machines. In terms of bulldozer as one of the most high-usage machines in supporting operations in open pit mines of the Electric Power Industry of Serbia, the application of both model approaches is compared, as well as the estimations and conclusions are made.

The problem of oil flow in model reservoir is solved at the preset harmonic time variations in differential pressure at the model sides. Hysteresis effects of capillary pressure upon the change in direction of fluid expulsion are considered. The influence of water level fluctuations on removal of possible capillary blockage by water from wellbore zone is estimated. The action of alternating pressure pulses on oil-filled formation is analyzed. It is shown that harmonic change of water pressure promotes removal of immobile water blocked in capillaries from wellbore zone. The results of full-scale experiments on wave action on wellbore zone and oil recovery enhancement are presented.

The approach to further development in engineering geologic mapping of mineral reserves with respect to quality levels based on geoinformation models of deposits is substantiated. The algorithm and methods for delineation of clusters in the area of a seam using a vector index composed of simple indicators characterizing useful and harmful properties of coal are explicated. The results of new software trial are presented in the form of distribution of coal reserves for coking and power generation by quality levels and visualization of delineated clusters by means of plotting quality maps.

Theoretical aspects of studying stability of natural systems depending on investigation purposes are briefly analyzed. Applicability of the watershed/landscape concept of nature management to study transformation of geosystems disturbed by gold placer mining is substantiated. In terms of a model site within the limits of the Ket-Kap cluster of placers, the data on the degree of such transformations are given, and mid- and large-scale landscape mapping is performed using the modern remote sensing techniques. The qualitative indicators of transformation degree under placer mining are given for valley nature systems depending on watershed order. The relevance of the remote sensing in estimating the degree of transformation of natural systems at objects of gold placer mining at regional and local levels is demonstrated.

Airflow disorder in inlet shafts and related crossheadings, caused by local natural ventilation pressure, is a complicated thermodynamic phenomenon. The conception of local natural ventilation pressure is proposed based on a simplified ventilation system. Airflow disorder principle is analyzed theoretically and verified by similar simulation experiment and in-situ study. Research results show that local natural ventilation pressure will form when average temperature difference or density difference of air-column exists among inlet shafts in an underground mine with exhaust ventilation. When changing in a large range, local natural ventilation pressure will cause airflow disorder in inlet shafts or related crossheadings. The research results have guiding significance for promoting the stability of ventilation system and improving the working environment of underground mines.

Organic and inorganic luminophores having similar parameters of luminescence as diamonds are selected. Based on the excerpted luminophores, indicators are synthesized. Spectral and kinetic characteristics of luminophores are experimentally determined for deciding on optimal compositions to ensure maximum extraction of diamonds in X-ray luminescence separation owing to extra recovery of non-luminescent diamond crystals. As the components of luminophore-bearing indicators, anthracene and K-35 luminophores are selected as their parameters conform with the luminescence parameters of diamonds detected using X-ray luminescence separator with normal settings.

Activation of sulphides by heavy metal ions is discussed. A brief analysis of modern ideas on mechanism of activation of sphalerite, pyrite and galena by copper sulfate and lead nitrate is given. It is shown that the current technology insufficiently conforms with the experimental and practical data on activation of minerals. A new mechanism of mineral flotation activation is proposed based on the action of physical adsorption species of collecting agents, which allows explaining suppression of flotation under increased concentrations of activator and flotation of sulphides without collectors. The new mechanism integrates the action of mixed potential, activation of minerals by heavy metal ions and the collectorless flotation into a common theoretical framework.

The research findings on efficiency of hardly soluble low-hydroxyethylated iso-nonylphenols as regulators of selective flotation are presented. The methods for increasing their solubility are developed, which are based on using unsaturated carboxylic acids as wedding agents for alkaline salts. It is shown that addition of such wedding agents to ethoxylated iso-nonylphenols makes it possible to obtain stable aqueous micellar solutions or emulsions under much lower temperatures, as well as ensures permanence of the process and efficiency of regulating agents in selective flotation of phosphorus-bearing ores with fatty acid collector. Efficiency of the developed methods is proved by in practical application of one of them, which improved ore dressing performance, reduced labor content, energy input and preparation time of solutions, and provided considerable economic effect.

The recovery and rate of galena flotation depending on galena grain size and butyl potassium xanthate concentration are studied at the laboratory scale. It is found that the recovery and flotation rate decrease with galena grains smaller than 38 μm and with the lower concentration of the collector. Galena grain size has larger influence on the recovery by flotation than the collector concentration. These findings are the result of analysis of multivariable correlations between the galena recovery in flotation, collector consumption and galena grain size since partial correlation coefficient and general correlation coefficient point at close relationship between these parameters.

Tin-bearing tailings of the Solnechny Mining and Processing Plant (MPP) in the Khabarovsk Territory are studied with a view to producing tin and copper concentrates. The features of the material constitution of tailings and their influence on the process flow diagram development are described. Processability of the Solnechny MPP tailings is tested, and PFD is developed using the modern methods of disintegration, including cavitation and ultrasound. The semi-commercial-scale implementation of the proposed PFD has allowed production of copper concentrate at copper content of 18.28% and recovery of 60.48%, tin concentrate at tin content of 11.35% and recovery of 50.88%, and rejects with the tin and copper contents of 0.139 and 0.154%, respectively. The recovery of tin and copper has made 46.66 and 38.45%.

The review presents materials on the scientific principles underlying the development, preclinical and clinical research, registration and control of the safety of biosimilar medicines produced using genetic engineering techniques. The number of biosimilars used in the clinic, defined as «biosimilars», is steadily increasing. The features of biotechnological preparations are presented, that requires a special approach to assessing the newly developed preparation evidence of similarity with the original (reference) preparation. To ensure the effectiveness and safety of their use, the procedure for registration of such medicines is determined by the regulatory framework governing the requirements for proof of similarity with previously approved biological medicinal products. The data concerning the differences in the nature and scope of studies at the stages of quality assessment, preclinical and clinical development of biosimilar and original drugs are performed. The issues related to extrapolation of clinical trial results and the issues of medicines interchangeability are reported. The modern information on international experience of biosimilar medicines registration, scientific achievements and regulatory requirements concerning evidence of similarity in assessing the quality, effectiveness and safety of biosimilar biotechnological medicines («biosimilars») has been reported.

Despite the success in developing direct-acting antiviral drugs, in routine clinical practice the use of interferons remains relevant. Parenteral administration of interferons is accompanied by systemic side effects and presents significant inconveniences for patients. A drug based on interferon λ-1, which has high enteric bioavailability and ensures its high concentration in the liver, is promising for the effective treatment of hepatotropic viruses. The aim of the investigation was to study the antiviral activity of an oral medicine based on interferon λ-1 immobilized on polyethylene glycol-1500 by electron-beam synthesis technology. Materials and methods: Real time PCR, Western blot and immunohistochemical method were used to study antiviral activity of tested medicine against hepatitis C virus. Results and discussion: The tested medicine retains antiviral activity against hepatitis C virus. All obtained results are consistent with each other. A 50 % inhibitory dose is in the range of 0.008-0.08 ng/ml. Conclusion: IFN λ-1 immobilized on polyethylene glycol with the help of radiation synthesis technology can be considered as a prototype of an oral drug for the treatment of viral hepatitis, in particular hepatitis C.

The aim of the investigation is to study the pathomorphological changes in the anterior vaginal wall in women with stress urinary incontinence, who received correction using an erbium laser Fotona. Material and methods. The complex pathomorphological analysis of the biopsy specimens of the vaginal mucosa (VM) in women with stress urinary incontinence (SUI) before and after exposure Er-YAG-laser was performed. Results. It is shown that the main signs of remodeling of VM during SUI are disorganization of fibrillar structures (collagen and elastic fibers) of the intercellular matrix, microcirculation disorders, dystrophic and atrophic changes in the epithelium. After application of laser technology IncontiLase in the VM, signs of stimulation of neocollagenogenesis and neoelastogenesis processes, enhancement of neoangiogenesis, replenishment of a population of synthetically active fibroblasts, increased proliferation (an increase in the index of Ki-67-positive epitheliocytes by 67 %) and improvement of the structure of the vaginal epithelium are revealed. Conclusion. The use of an Er-YAG laser in the correction of SUI in women potentiates the restoration of the morphofunctional organization of VM.

Objective: to research features of vegetative regulation and their relation to eating behavior in women with different types of obesity and type 2 diabetes. Methods. 106 women were examined; survey of women included anthropometric measurements, study and calculation of heart rate variability were performed with “VNS-micro” (Neurosoft, Russia); recording of food consumption in 24hs were assessed. The types of eating disorders (ED) were detected with DEBQ. Results and discussion. Adipose tissue topography (ATT) among women is associated with vegetative regulation, as well with ED. So, the spectrum of both high-frequency (HF) and low-frequency (LF) oscillations are increased in women with gynoid type of ATT. Conversely, android type of ATT is characterized by overall decline of LF and HF oscillations with residual dominance of the sympathetic part. An increase in the relative contribution to the total power of the very low-frequency (VLF) spectrum among women has been revealed. Emotional and compulsive eating behavior disorders were prevalent in women with gynoid type of ATT, external type of ED prevailed among women with android type of ATT. Women with android type of ATT and type 2 diabetes had minimal severity of eating behavior disorders. The increase in activity of the sympathetic and parasympathetic parts of the autonomic nervous system in women with gynoid type of ATT was combined with sympathoadrenal and vagoinsular reactions, which is confirmed by a positive correlation of emotional ED with HF and LF, and there was a negative correlation of restrictive ED with LF. A negative correlation of emotional ED with VLF among women with android type ATT was detected. There are no correlation of ED indices and activity of the autonomic nervous system among women with android type of ATT and type 2 diabetes. It can be associated with manifestations of diabetic vegetative neuropathy.

The aim of the research was to study the effectiveness of bullous keratopаthy surgical treatment by modified method of operative intervention including intra-chamber injection of autologous blood mononuclear cells suspension with subsequent layering on the inner surface of the cornea. Material and methods. Clinical studies were conducted among 44 patients who comprised two groups: the main group (21 patients) and comparison group (23 patients). The treatment of the main group was carried out by a new method. The treatment of the comparison group was traditional pharmacotherapy. Results and discussion. The cornea hydration reduction in the main group was noted during the first 5 days after surgical treatment. The moderate decrease of corneal oedema in the comparison group started on 10-12 days. The pachymetry index decreased by 11 % in the main group and by 3.1 % in the comparison group after 1 month of treatment. Visual acuity increased fivefold in the main group and twofold in the comparison group. Conclusion. The use of the modified surgical treatment of the bullous keratopаthy promotes a faster decrease in the cornea hydration and stable improvement in visual acuity in the postoperative period compared with the course of conservative treatment.

The aim of the investigation was to study the structural features of the liver cell populations and gastric mucosa at varying intensity of Helicobacter pylori colonization in patients with HCV and HBV infection markers. Material and methods. The clinical and morphological study of 95 patients with markers of HCV and HBV infection and with gastric dysfunction (52 men and 43 women aged 16 to 66 years) and 56 patients with chronic gastritis has been carried out. The results have been compared to the degree of H. pylori infection. Results and discussion. It is shown that in all patients with chronic hepatitis the gastric mucosa is involved in the pathological process while the fibrosing form of lesions - gastropathy predominated. The significant correlation between structural changes and the hepatitis activity degree as well as with the presence of H. pylori has not been revealed. Analysis of the stomach structural changes in patients with chronic gastritis, depending on the presence of H. pylori and the infection intensity showed that the catarrhal-fibrotic process predominates in gastric mucosa in case of high degree of H. pylori activity and fibrosing changes predominate in the absence of H. pylori .

In recent years there is intensive growth of the number of genetic diseases such as imperfect osteogenesis and hypophosphatemic rickets. Treatment of this category of patients includes surgical intervention, however in many cases there are recurrences of the disease and the patients have to undergo multiple surgeries. It is known that study of concentration of growth factors and regulatory polyproteins can help in understanding of pathogenetic course of genetic diseases. Material and methods. We studied growth factors and their receptors, bone markers and vitamin D by enzyme-linked immunoassay in blood serum of patients with hypophosphatemic rickets and osteogenesis imperfecta during surgical treatment. The analysis was carried out according to technique from manual to sets eBioscience (TGF-β1, TGF-β2, VEGF-A, VEGF-R2, VEGF-R3), Immunodiagnostic systems (IGF-1, osteocalcin, vitamin D, β-CrossLaps), Invitrogen (VEGF), RayBiotech Inc. (FGF-1, FGF-2, TGF-α, SCF, SCFsR), Mediagnost (IGF-2), QULDEL (pyridinoline), Enzo (DKK-1). Results. It has been established that concentration of growth factors IGF-1, VEGF, FGF-2, TGF-β1, TGF-β2 and their receptors VEGF-R3, SCFsR, bone markers osteocalcin, pyridinoline, as well as vitamin D in blood of patients of different groups at different stages of treatment varied. However, concentration of IGF-1, VEGF-R2 before surgery and ТGF-α on the 60^th day, SCF on the 60^th day in patients with hypophosphatemic rickets and osteogenesis imperfecta did not differ.

The aim of the research is to study the connection between the five-day cumulative fluid balance and the outcome of a critical condition in the surgical group of newborns. Material and methods. The study involved 30 newborns with necrotizing enterocolitis in stage IIIB according to Walsh - Kliegman. Groups were formed by the criterion of outcome. Analyzed parameters were age and body weight of participants, hematocrit number; the cumulative five-day fluid balance expressed as a percentage of the initial body weight. The data were carried out by nonparametric statistics. Results and discussion. The only independent factor determining the probability of death from necrotizing enterocolitis of newborns is the gestational age and the body weight as its derivative. The likelihood of an unfavorable outcome in necrotizing enterocolitis of the newborn doesn’t depend on the five-day cumulative fluid balance.

Dystonia is hyperkinesis characterized by involuntarily repetitive muscle contractions in one or more body areas. It leads to the appearance of a pathological posture and disruption of arbitrary movements. This definition is the most common, but not completely exhaustive, because of the phenotypic polymorphism of the disease. There is not unitary methodology for epidemiological research. Also the disease clinical symptoms are very polymorphic. These reasons make the results of the study incomplete and inaccurate. Implementation mechanism of dystonic hyperkinesia is still insufficiently studied. At the present time the disease multifactorial nature is the leading hypothesis whereby the genetic determinacy can be realized under the influence of exogenous factors. The diagnosis of the cervical dystonia is clinical and sets on the manifestations of the pathological posture of the head and neck. The disease begins at the active working age and proceeds with the functional deficit formation leading to difficulties of domestic and professional nature. This leads to psychological, social dysaptation and disability of patients. The proven effective treatment for the cervical dystonia is the use of botulinum toxin of type A (the grade of recommendation A).

Early detection of children sight disturbances allows ophthalmologists to prescribe in time preventive activities and treatment, to stop developing pathology, and to prevent complications initiation. The purpose of our study was to elaborate and introduce into practice a method of distant screening examinations of schoolchildren using telecommunication facilities. Material and methods. We developed an interactive computer program for distant examination of visual acuity, long or short sight shift in refraction , diagnostics of astigmatism and pathology of macular area. The results of the examination were automatically recorded in a computer database. The program was hosted on the clinic website. Examination was performed simultaneously for up to 5 schoolchildren sitting in a computer class of their schools. The examination lasted from 4 to 8 minutes for the group depending on the quantity of the invoked tests. Results and discussion. 28,983 schoolchildren underwent the distant screening of vision. Visual acuity of 1.0-0.9 was revealed in 14345 people (49.5 %), 0.8-0.2 - in 11187 people (38.6 %) and less than 0.1 - in 3451 people (11.9 %). The test is not specific in terms of the type of pathology, but it allows us to conclude that more than half of schoolchildren have a reduced vision. A method of distant screening vision examinations is reliable and high-performance. Database of the examination results is helpful to diagnose pathology at early stage, to track its dynamics and to inform parents in time on whether an expanded investigation and ophthalmological treatment of their children is necessary.

The question on the peculiarities of stroke course in persons working under the influence of unfavorable occupational factors has not been sufficiently studied. The aim of the study was to assess the severity of stroke and the severity of the neurological deficit in the acute period of stroke in men exposed to occupational factors of physical and chemical nature. The analysis of the recovery dynamics in the acute period of stroke in 241 patients (the main group) exposed to harmful occupational factors (general vibration, production noise, electromagnetic radiation (EMR), toxic-dust factor) was carried out. The comparison group consisted of 76 patients with stroke who did not work under the influence of harmful occupational factors. To objectify the severity of the condition and assess the severity of the neurological deficit, the National Institutes of Health Stroke Scale (NIHSS) was used in the scores for admission and dynamics of an acute stroke on day 21 of the disease (NIHSS 1 and NIHSS 2). An initially expressed deficit (NIHSS 1 scale) in patients with stroke in the main group was established, compared with the comparison group, and the highest indicator was found in men who contacted EMR. Significant differences between the indices of the initial neurological deficit of the main group and the comparison group were revealed only among young men who had contact with EMR, as well as with the toxic-dust factor. The best dynamics of recovery in the acute period of stroke was found in the comparison group, and in the main group among young people, except for the production group with the influence of the toxic-dust factor. In patients with ischemic stroke, the minimal neurological deficit to the end of the acute period was in the comparison group, and in the main group - in young men who had the influence of general vibration, as well as noise. The severe course of hemorrhagic stroke was established in the comparison group, and in the main group - among patients who had contact with EMR. The elderly of the main group had the maximum severity of the neurological deficit, with the exception of patients who had the effect of a toxic-dust factor.