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THE PURPOSE. The features of the rheological behavior of composite fuel oil suspensions depending on the shear rate, temperature and composition of the composite fuel are considered.METHODS. Suspensions with a coal content of 30, 40 and 50% (by weight) were prepared. The mixing time varied from 1 to 10 minutes. The samples of fuel oil were examined using a Rheomat RM 100 rotary viscometer to determine the values of dynamic viscosity at different shear rates and temperature.RESULTS. The results of experimental studies of the dynamic viscosity of fuel oil as a function of the shear rate and temperature are obtained. The best values of coal dust content in fuel oil suspensions for fuel transportation have been determined.CONCLUSION. The obtained research results can be used by both energy companies and transport companies to determine the technological viscosity indicators of composite suspension fuels used as boiler fuel and fuel for marine engines.

The article considers mathematical models of two spheroidal spiral-frame emitters, built on the basis of a general approach involving the use of an integral representation electromagnetic field. The internal problem of electrodynamics is reduced to a system of Fredholm integral equations of the 1st kind. The resulting system was solved by the method of moments with piecewise constant basis functions and delta functions as test functions. In this case, the local linearization of the generating conductors of the structures under consideration was carried out. The dependences of current distributions, input resistance, and radiation characteristics of structures on frequency have been studied. It is shown that standing, traveling, and mixed current waves can exist in the structures under consideration. The current regime is determined by the wave sizes and the geometry of the structures and determines the behavior of the wave resistance in the frequency range. Despite the similar geometry, the characteristics of the considered structures have certain differences.

Background. Among the existing experimental models of cerebral stroke in large animals, there is no possibility to create a focal brain infarction of limited volume, which would provide an opportunity to evaluate both the endogenous potential of neuroregeneration and to establish the effectiveness of new drugs on postischemic brain remodeling. Aim. Development of a method for modeling small-focal ischemic infarction of the cerebral cortex in a mini-pig. Material and methods. The study used mature female mini-pigs of the Vietnamese fold-bellied breed. Two-level occlusion of the great vessels was performed by ligation of the right common carotid artery and subsequent cauterization of the distal branches of the middle cerebral artery. In the postoperative period, the survival rate of animals and neurological deficit were assessed. On the 7th day, the animals were taken out of the experiment, the brain was isolated from the cranial box. Macroscopic and microscopic examinations included analysis of the localization and area of cerebral infarction, as well as morphological changes in the infarcted and peri-infarcted areas of the cerebral cortex. Results. With a 100% survival rate of experimental animals on the 3rd day after the operation, a neurological examination revealed violations of skin sensitivity and muscle tone in the hind and fore limbs, which partially recovered a week after the onset of ischemic stroke. Macroscopic examination of the brain on the 7th day after the operation visually revealed a small-focal ischemic cerebral infarction in the parietal lobe of the left hemisphere. Histological analysis of the cerebral cortex revealed a wedge-shaped necrotic focus of ischemic injury. In the peri-infarction region of the brain, reactive tissue changes with preserved nerve cells, mostly without visible damage, were found. Conclusion. The developed two-level method of stroke modeling in a mini pig induces ischemic cerebral infarction of limited volume in the parietal lobe; non-critical histological changes in the peri-infarct area and a slight neurological deficit suggest the possibility of using this model to develop new methods of stroke therapy.

Introduction. The testing for mitochondrial dysfunction has become routine assay for drug and cosmetics safety evaluation. Mitochondria are targets of many pharmaceutical and therapeutic agents that can damage them and lead to changes in morphology and function. Spermatozoa have one of the highest ratios of mitochondria to body size, they lack the cytoplasm between the mitochondria and the plasma membrane, which makes them a good potential model for a rapid test on mitochondrial toxicity. The aim of our work - assessment of motility and mitochondrial membrane potential of bovine spermatozoa Bos taurus taurus in the presence of T-2-toxin and deltamethrin. Material and methods. T-2-toxin and deltamethrin were used as toxins. The main parameters studied were the level of mitochondrial potential (using the MitoTracker™ Green FM dye), sperm motility and their relationship. Results. We found a strong correlation between the motility of bovine spermatozoa and the mitochondrial potential of their mitochondria (R>0.87; p

Diagnostics of electrical equipment at industrial enterprises is an urgent task, since the failure of the main and auxiliary electric drives can lead to significant economic losses for the enterprise. The main share of failures of asynchronous motors is caused by their overload and, accordingly, overheating of the stator winding. Such overheating leads either to an interturn circuit and engine failure, or to a significant reduction in its resource. Therefore, winding temperature control is an important task. In this paper, we propose an algorithm for calculating the temperature of an induction motor with a squirrel-cage rotor with a changing load on the shaft using an equivalent thermal circuit consisting of 10 main nodes. In the work, methods of mathematical modeling were applied using previously developed software, as well as Excel. The task was set to check the possibility of using an equivalent thermal circuit for dynamic modes of operation of electrical equipment. The results of the work allow us to conclude that the developed algorithm can be used for further modeling of both stationary and non-stationary thermal models of asynchronous motors with a squirrel-cage rotor.

The article deals with the issue of the influence of solar power plants on the operation of relay protection and automation devices. The development of simulation models of electric power systems in the Simulink MATLAB environment has been carried out for three cases: power is supplied entirely from a solar power plant; power is supplied from the traditional source of the electric power system; the power is supplied partly from the solar power plant, partly from the traditional source of the electric power system. The description of the main parameters of the blocks of the simulation model is made. A study was also made of the influence of renewable energy sources on the sensitivity of relay protection, which directly depends on the level of short-circuit currents. Graphs of the dependence of the two-phase short circuit current on time are plotted. The conclusion is made about the decrease in the sensitivity of the relay protection in the presence of a solar power plant in the electric power system. The results obtained make it possible to calculate the parameters of various operating modes of the system, the results of which can be used to configure relay protection and automation devices.

Long-term phased development of a multi-layer field, including tens and hundreds of oil-bearing horizons and local deposits, combined with their vertical and horizontal separation, creates conditions for the formation of residual oil reserves. For the purpose of identifying and spatial localization of residual reserves, an algorithm for retrospective analysis was developed and applied on the example of the Upper and Lower Devonian terrigenous deposits of the Romashkinskoe oil field, which have been developed since 1952. The long history of geological study and development of oil-bearing formations of the Pashiysky D1 (layers g and e), Mullinsky D2, Ardatovsky D3, Vorobyevsky D4 and Biysky D5 horizons is analyzed according to the data of 2605 wells. It is proposed to single out 6 categories of formations and the reserves contained in them. Previously undeveloped formations composed of conditioned reservoirs are classified as category 1. Formations composed of more clayey and less permeable reservoirs are awarded with category 2. Category 3 includes previously developed formations, but left before reaching the limit of water cut, and category 4 – currently being developed intervals. The least promising are those that are stopped after reaching the maximum water cut (category 5), as well as wedged out, replaced by non-reservoirs or considered water-bearing (category 6) formations. Categories were mapped to identify, visualize and describe the main patterns in the distribution of residual reserves, which are established both in single wells and in bypassed oil that include a group of wells. The algorithm was tested on the corporate information base of historical data on geological exploration, research and development of the Abdrakhmanovskaya area of ​​the Romashkinskoe oil field. Examples of experimental workover operations to include the identified residual reserves in the development are given.

Decreasing negative impact of industrial emissions to the atmosphere and prolonging fossil fuel usage period are urgent issues of fuel and energy sector. In view of this problem, injection of flue gases into oil fields to increase oil recovery may be considered as environmentally safe and economically rational way for beneficial use of greenhouse gas emissions. To effectively displace oil with flue gases it is important to consider many factors: influence of composition of the flue gases and oil, miscibility conditions, injection regimes, etc. Flue gases, a product of fuel combustion in air, can be produced as a result of oil self-ignition when air is injected into a reservoir with light oil (thermal gas method). Flue gases from natural gas, fuel oil or coal combustion in power plants or other processes that burn fossil fuels can also be used for injection into the reservoir. This paper presents an analysis of the world laboratory and industrial experience in studying efficiency of oil displacement using flue gases. Conclusions are presented about optimal criteria for implementation of this process and directions for further research.

The phenomenon of self-excitation of thermomechanical vibrations of current-carrying conductors, experimentally discovered by academician A.F. Ioffe, is of practical interest as a possible explanation of the phenomenon of galloping conductors of overhead power transmission lines (OHL) – low-frequency vibrations with frequencies of ~ 1 Hz and with amplitudes of the order of the static conductor sagging. To build the theoretical foundations of this phenomenon, as a special class of self-oscillating systems, it is necessary, first of all, a model of conductor vibrations in the OHL span. With regard to the most studied type of conductor vibrations, high-frequency aeolian vibration, excited by sign-alternating aerodynamic forces from the Karman vortex street, the classical model of a straight string is reasonably applied. However, to study low-frequency vibrations of the galloping type, it is necessary to take into account the effect of sagging of the conductor, the associated elastic tension and, in some cases, the nonlinear nature of the vibrations. The article presents two models for calculating the natural vibrations of sagging conductors (cables) within the framework of the technical theory of flexible threads, assuming the constancy of the tension force along the length. The first model describes linear oscillations of an elastic conductor in the sagging plane. For a system of equations with respect to the displacement components given in natural coordinates, an exact solution of the Sturm-Liouville problem with estimates of the frequency ranges arising is obtained. The second model describes nonlinear vibrations of an elastic conductor in the sagging plane and pendulum vibrations accompanied by an exit from it. The solution of the problem is based on the principle of possible displacements using the Ritz method. The structure of the frequency spectrum and the natural forms of transverse vibrations are studied. The developed models are intended for further investigation of thermomechanical vibrations of conductor and flexible cable systems.

The paper is devoted to some methodological aspects of interdisciplinary analysis of Projects for Complementary Currencies (CC-Projects) have been sometime realized both in domestic and foreign economic practice. The analysis is focused mostly on the revealing both of the CC-projects’ basic characteristics and conditions necessary for the effective CCs emission and their circulation. An emphasis is also paid to sampling of possible methodological approaches to an elaboration of successful projects and relevant payment systems. Among the main missions carried out by the projects (especially based on the local currencies, LCs) the authors have highlighted the revival of the local economies, mitigation or even complete absorption of external shocks (due to the countercyclical nature of the action of complementary currency acting as a buffer, countercyclical buffer) and, in addition, the supporting of social trust. It might be suggested that in some sense CCs are focused on turning the target territories for them into reliable islands of socio-economic stability. The paper contains its authors’ effort to reveal why some observed projects with a multifunctional load relevant to them do not always manage to serve as an effective tool for strengthening market relations on the ground. This is one of the important components of the undertaken empirical analysis of different CCs which one time were implemented in various areas of many countries of the world.

Generalized approximate weak greedy algorithms (gAWGAs) were introduced by Galatenko and Livshits as a generalization of approximate weak greedy algorithms, which, in turn, generalize weak greedy algorithm and thus pure greedy algorithm. We consider a narrower case of gAWGA in which only a sequence of absolute errors { ξ n } n = 1 ∞ {\left\{{\xi }_{n}\right\}}_{n=1}^{\infty } is nonzero. In this case sufficient condition for a convergence of a gAWGA expansion to an expanded element obtained by Galatenko and Livshits can be written as ∑ n = 1 ∞ ξ n 2 < ∞ {\sum }_{n=1}^{\infty }{\xi }_{n}^{2}\lt \infty . In the present article, we relax this condition and show that the convergence is guaranteed for ξ n = o 1 n {\xi }_{n}=o\left(\frac{1}{\sqrt{n}}\right) . This result is sharp because the convergence may fail to hold for ξ n ≍ 1 n {\xi }_{n}\hspace{0.33em}\asymp \hspace{0.33em}\frac{1}{\sqrt{n}} .

The article considers the factors that affect the spectral characteristics of acoustic noise recorded in active horizontal wells during logging. Based on the results of physical experiments performed on well models, the presence of resonance phenomena in the acoustic volume of the wellbore, the influence of the location of sensor and the tool body on the measurement result under identical conditions, the need to calibrate downhole tools for bringing their characteristics to a single scale are shown.

Temperature measurements in downhole conditions (well thermometry) are widely used in monitoring the development of oil and gas reservoirs. With the use of thermometry many oilfield tasks are solved: determination of the working intervals, behind-the-casing flows, casing leakage etc. Variation of temperature in formation is caused by thermodynamic effects: Joule-Thomson and adiabatic. One of the main effects in determining the working intervals by downhole thermometry methods is the Joule-Thomson effect, which is associated with the Joule-Thomson coefficient, characterizing the composition of the fluid flowing from the perforated formation into the well. Therefore, it is necessary to know the value of Joule-Thomson coefficient for different fluids, especially it is important for quantitative interpretation of thermometry data. Currently, the Joule-Thomson coefficient is well studied for various pure fluids and gases, but practically not investigated for emulsions of different types. Meanwhile, the inflow of oil and water from the formation often leads to the formation of emulsion in the bottomhole zone of the formation. Therefore, experimental determination of Joule-Thomson coefficient for such systems and study of thermohydrodynamic processes during emulsion filtration is relevant. The paper presents the results of experimental studies of thermohydrodynamic processes during filtration of emulsion through a choke cell. The description of the experimental setup and the experimental procedure are given. The main design features of the throttle cell, approaches to reduce heat transfer during the movement of fluid through the throttle cell are discussed in detail. The data of experimental studies of temperature and pressure changes during filtration of type “oil in water” — oil dispersion in water and reverse emulsions of type “water in oil” — water dispersion in oil on the throttling cell are given. The paper also obtained estimates of the Joule-Thomson effect for liquids like water, oil and oil-water emulsions.

The largest share of failures of asynchronous motors in industry is associated with overheating of the stator winding insulation as a result of improper operation of the equipment. In this paper, methods of mathematical modeling of thermal processes of an asynchronous motor with a squirrel-cage rotor are applied to assess the thermal state of the elements of the electric motor design. The simulation is based on the method of equivalent thermal circuits for stationary heating. The mathematical model consisting of 10 main units of the electric machine is taken as a basis. The aim of the paper is to experimentally test the adequacy of the proposed mathematical model and evaluate the possibi­lity of its application for diagnosing the state of the electric motor by measuring the stator current without using built-in sensors. The simulation results were verified experimentally using thermal imaging equipment. Based on the results of comparing the mathematical model and experimental data, it was concluded that the proposed model can be used to study the thermal regimes of an asynchronous motor with a squirrel-cage rotor.

Nanoporous materials are employed in numerous technologies of matter upgrading by mass separation and conversion (heterogeneous catalysis). The chapter deals with the measurement of guest diffusion in such materials and, thus, with the determination of a key parameter for performance enhancement of these technologies. The introduction of two “microscopic” measuring techniques (PFG NMR and microimaging), which are in the focus of this chapter, gave rise to a paradigm shift in our understanding of mass transfer in such materials. Nanoporous host-guest systems are, moreover, shown to serve as an ideal model system for investigating spreading phenomena quite in general. Ample options of investigation range from the comparison of equilibrium and non-equilibrium phenomena towards the investigation of conversions of both the spreading individuals and their environment.

Expansions in a finite frame are considered as a continuous linear redundant coding. It is shown that coding of an element from an $$N$$ -dimensional space with a frame consisting of $$(N+M)$$ elements allows detecting up to $$M$$ errors and correcting up to $$\left\lfloor\dfrac{M}{2}\right\rfloor$$ errors. It is also pointed out that these results are sharp. The results are direct continuous analogs of the classical statements from the discrete coding theory.

The mutagenic activity of the drug based on strains of lactic acid and propionic acid microorganisms showed that the studied drug and its metabolites did not induce reverse mutations from histidine auxotrophy to prototrophy in histidine-dependent Salmonella typhimurium TA98 and TA100 strains. The number of revertant colonies in the experiment and control differed significantly less than 2.0 times. The drug had a low MI of 1.0-1.1 for the TA98 strain and 0.96-1.07 for the TA100 strain. The data obtained indicate the safety of the drug based on lactic acid and propionic acid microorganisms, as well as the possibility of its further use in agriculture and veterinary medicine.

We consider the undivided boundary value problem for singularly perturbed linear integro-differential equations of th order with Fredholm’s integral terms have an initial jump of the phenomenon th order on the left end of the segment. Defined regular and boundary layer members of the asymptotic expansions of the solutions. Regular members of the asymptotics constructed in the form of integro-differential equations, which different from the usual unperturbed equations by the presence of additional term called initial jump of integral terms. The values of the initial jumps are defined. Boundary conditions for the regular members of the asymptotics also contain additional term, called an initial jump of the derivatives th order. Thus, for the determination of the regular members of the asymptotics obtained boundary value problems for linear integro-differential with additional parameter. To determine the boundary layer of the asymptotic expansion of solution we obtained initial problems for homogeneous an inhomogeneous ordinary differential equations with constant coefficients. Exponential estimates for boundary layer terms of the asymptotics are obtained. A theorem of existence and uniqueness and the asymptotic representations of solution with an estimate of the remainder term of the asymptotics. It is found that the constructed asymptotics approximation to the solution of the original singularly perturbed integro-differential boundary value problem is uniformly throughout the considered interval.

The paper presents the results of comparing the integral characteristics of ignition and combustion of coal and composite fuels, prepared from coal processing waste in a dry and wet state, in a model combustion chamber. We calculated the relative fuel performance coefficients, taking into account the established ignition delay times, fuel burnout duration, concentrations of gaseous anthropogenic emissions, as well as temperature changes (reduction at the initial stage and growth during rapid combustion) in the model combustion chamber. It was shown that the ignition delay times of coal processing waste in a dry state are 30–70% lower than in the initial wet state. However, burning wet coal processing waste provides the lowest concentrations of NOx and SO2 (5–44% lower than in a dry state and 35–70% lower than they are for coal). Considering the main environmental, economic and energy performance indicators, optimal conditions were established for the combustion of abundant coal processing waste as part of water-containing slurry fuels. It was established that the relative performance coefficient of slurry fuels ranges from 2.05 to 58.87 when varying the moisture content and component composition. This coefficient is maximum for wet filter cake without oil. This allowed us to conclude that wet coal processing waste is highly promising.

Currently, sources of meteor particles that fall into the upper atmosphere when the Earth moves in its orbit are being actively investigated. For this, the radiometric method is very actively used. This method is based on the radiolacationof meteor trails that appear as a result of the ionization of air in the mesosphere – the lower thermosphere (75-110 km) during the combustion of meteors. Radiometric observations of meteor showers are actively conducted at Kazan Federal University. Regular observations began in 1978, and the first data measuring the heights of meteor combustion began in 1985. In 2015, a Skiymet-type meteor radar of joint Canadian and Australian production was installed. The KFU meteor radar consists of a phase interferometer (five two-element crossed receiving antennas of the Yagi-Udo type) with bases of wavelengths 2 and 2.5, a transmitting antenna (crossed three-element antennas), as well as a transmitter with a power of 15 kW per pulse (average power of about 1 kW) with a carrier frequency of 29.75 MHz and a pulse repetition frequency of 1594 Hz. The meteor radar of Kazan Federal University (56N, 49E) is constantly being upgraded. The results of modernization are presented: a significant increase in the number of meteors and the accuracy of the estimation of angular coordinates and heights.

Owing to their potential for eco-friendly matter upgrading by molecular sieving and shape-selective conversion, nanoporous materials are among the pioneers of green chemistry. The performance of their application is often controlled by diffusion, i.e. the rate of mass transfer within these materials. This mass transfer, however, is rather complex and subject to numerous influences. Unambiguous diffusion measurement has thus remained a challenge to this day with errors in the interpretation of experimental data being all too common. The present feature reports the efforts of an IUPAC initiative to overcome these limitations.

Earlier, in mice after a 30-day space flight on the Bion-M1 biosatellite, we found signs of a negative effect of weightlessness on the structure of myelinated fibers of the spinal cord tracts; these findings indicate their involvement in the pathogenesis of hypogravitational motor syndrome (HMS). In the present study, under conditions of hypogravity modeling by the hindlimb unloading, we obtained data on destructive changes in the myelinated fibers of the motor posterior corticospinal tract (tractus corticospinalis posterior), sensitive anterior spinocerebellar tract (tractus spino-cerebellaris anterior), and the gracile fascicle (fasciculus gracilis), as well as in the tibial fascicle (fasciculus tibialis) of the sciatic nerve of mice 30 days after unloading. The obtained data confirm our hypothesis on the role of disturbance in the processes of myelination of nerve fibers during the development of HMS, both during space flight and under conditions of simulating hypogravity on Earth. Morphometric analysis after a 7-day period of readaptation did not reveal signs of restoration of pathological changes in myelinated fibers that arose after 30 days of hanging. However, preventive gene therapy (administration of a gene construct providing the synthesis of recombinant vascular endothelial growth factor, glial cell line-derived neurotrophic factor, and neural cell adhesion molecule, prior to hindlimb unloading) has been shown to be effective in the preservation of myelinated fibers in projection anterior spininocerebellar tract, compared with control animals that did not receive gene therapy. The research carried out at this stage gives ground to make a preliminary conclusion about the advisability of developing methods of preventive gene therapy to prevent the development of GDS during long-term space flights.

Aim. To study the dynamics of neuromotor regulation of the contractile function of “fast” and “slow” muscles in rodents during spinal shock by spinal cord transection at the level Тh11–Тh12. Methods. The experiments were carried out on laboratory rats weighing 140–180 g. The animals were divided into two groups: “Control” (8 rats) and “Spinal shock” (6 rats). The lower leg muscles, m. soleus and m. extensor digitorum longus (m. EDL), were dissected by partially isolating without disrupting the connection with the body's circulatory system. The sciatic nerve was stimulated with single electrical impulses (10 V, 0.5 ms). Contractions of both muscles caused by electrical stimulation of the sciatic nerve before and after the injection of the substances into the femoral artery — tubocurarine (1 mM) or norepinephrine (10 mM) — were recorded in animals of both groups. After spinalization, muscle contractions were re-recorded during electrical stimulation of the sciatic nerve before and 10 minutes after the injection of tubocurarine or noradrenaline into the femoral artery in the same concentrations. Results. After spinalization of the animal, the contraction force of the muscle m. EDL fibers increased to 0.43±0.03 g (p=0.040), but the temporal parameters remained unchanged. M. soleus, on the contrary, showed a decrease in the contraction time to 0.053±0.005 s (p=0.045), and no change in the contraction force was observed under these conditions. Intra-arterial administration of norepinephrine in the control group resulted in an increase of m. soleus contractions up to 1.21±0.17 g (p=0.048), and m. EDL — up to 0.57±0.07 g (p=0.043). The administration of norepinephrine in spinalized animals caused an increase in the contraction of m. soleus up to 1.21±0.09 g (p=0.047), and m. EDL up to 0.66±0.05 g (p=0.043). The blocker of postsynaptic cholinergic receptors tubocurarine administration reduced the force of contraction of both muscle types in both control [m. soleus up to 0.39±0.03 g (p=0.039), m. EDL up to 0.11±0.02 g (p=0.042)] and spinalized [m. soleus up to 0.34±0.05 g (p=0.039), m. EDL up to 0.15±0.04 g (p=0.040)] animals. Conclusion. The data obtained demonstrate the presence of significant differences in the mechanisms of control of contractile activity in the “fast” and “slow” skeletal muscles of warm-blooded animals; the persistence of the similar effect of the basic modulators on the contraction of both muscles with such a striking reaction to spinalization highlights the contribution of neurotrophic control to the functioning of “fast” and “slow” motor units.

The composition of the intestinal microflora of rats with experimental antibiotic-associated dysbiosis and after its correction with a biological product based on lactic acid and propionic acid microorganisms was studied. The results obtained indicate the normalization of the number of microorganisms when using the suspension form of the drug and make it possible to recommend its use in clinical practice for the correction of intestinal microflora disorders in animals.

Context: Previously, we investigated the relationship between the nature of the substituent at the 5-position of the uracil ring and the action of the corresponding uracil derivatives on immortalized lung cells. In the present study, we analyzed the impact of some 6-substituted uracil-derivatives on the regeneration potential of the lung cells (LC). Aims: To evaluate uracil derivatives capable of stimulating lung cell proliferation to create drugs that accelerate lung regeneration. Methods: The level of cell proliferation, maximum tolerated dose, and toxic effect of 6-substituted uracil derivatives (9 compounds) were studied on the immortalized lung epithelial cells and compared with the known drug 6-methyluracil. Results: The maximum tolerated dose of compounds for the LC line depends on the chemical structure of the compounds. The highest level of cell proliferation and tolerated was demonstrated when was used 3-methyl-6-cyclopropyluracil and 1-butyl-6-methyluracil. Conclusions: 3-methyl-6-cyclopropyluracil and 1-butyl-6-methyluracil exhibit a high proliferative activity in vitro so they could be recommended for additional studies of regenerative activity in vivo.