Search

Allele frequencies of three substitutions in the CCK (rs42891945 and rs42891946) and CCKBR (rs42670352) genes were identified in three Russian cattle breeds: Holstein (dairy), Bestuzhev (dual-purpose), and Kalmyk (beef). The most promising for further associative studies is the rs42670352 substitution in the CCKBR gene.

This paper presents a mathematical model of the combustion process of methane gas hydrate in a closed volume, taking into account the kinetics of its decomposition. The system of basic equations, which includes the equations of conservation of mass (for the entire mixture of gases and each component separately), momentum and energy, is supplemented by the conditions for the balance of mass and heat at the boundary of the phase transition. In this case, the dominant factor determining the intensity of hydrate decomposition is the Arrhenius-type kinetics and conductive heat transfer. Based on the numerical solution of the obtained system of equations based on the method of large particles, the temperature and concentration fields of the system are obtained and analyzed. It is shown that at the initial moment of time, the rate of decomposition of the hydrate according to the model that takes into account the kinetics of the decomposition process is higher than that according to the model that does not take it into account.

A mathematical model of the problem of heating a porous medium containing a liquid by an acoustic field is presented. Assuming that the main mechanism that converts the energy of the wave field in a porous medium into heat is the force of viscous friction between the saturating liquid and the skeleton, the function of a volumetric heat source for the process of heating a porous medium using an acoustic field is constructed. The dependences of the power of a heat source on the parameters of the wave field and the parameters determining the state of a porous medium are analyzed.

A mathematical model is proposed for the destruction of a methane hydrate monolith containing gas inclusions. In this formulation of the problem, it is assumed that there is a cylindrical cavity inside the hydrate monolith, initially filled only with methane. Since the conditions on the surface of the particle correspond to the conditions for the free existence of gas and water, the gas hydrate begins to decompose. On the basis of the obtained system, consisting of the equations of conservation of mass and heat, the temperature distributions in the “cavity - gas hydrate” system were obtained, and the influence of the initial temperature of the system and the temperature in the cavity on the dynamics of hydrate decomposition was analyzed.

In the work in a flat-one-dimensional formulation, a mathematical model and the results of modeling the combustion process of a gas hydrate as a result of its ignition with a mixture of methane and an oxidizer are presented. It was assumed that the rate constant of a chemical reaction depends on temperature according to the Arrhenius law. The solution was carried out by a numerical method based on the method of catching the phase transition front into the nodes of the spatial grid. On the basis of the obtained solutions, the distributions of the main parameters of the system, as well as the dependences of the highest temperature of the gas mixture and the rate of decomposition on time, were constructed.

Farm animals provide about 30% of humanity’s food requirements [1]. The world’s population’s demand for animal products is expected to keep growing. New technologies in animal husbandry can make it possible to meet this demand and to reduce its impact on the environment. Genomic selection plays a key role in this process as a promising and safe method for improving genetic qualities of farm animals. Before the widespread of genomic selection, high cost of genotyping was the main factor holding back an improvement of animal farming. However, today, the bottleneck in genomic selection is a limited amount of high-quality phenotypic data, which is still either difficult or too costly to obtain [2]. New technologies in animal phenotyping become of special attention. The current paper reviews the next-generation technologies in animal phenotyping and revels the main challenges limiting its widespread in the example of dairy cattle.

Using the ISSR-PCR technique, the genetic structure of nine sheep breeds (Ovis aries) bred on the territories of Russia and Mongolia was examined. Species-specific and breed-specific DNA fragments were identified. For the first time, data on the genetic diversity of Telengit and Buubey sheep breeds were obtained. The main parameters of the genetic diversity and the breed structure were assessed, and the phylogenetic relationships and genetic distances between the studied breeds were determined. Using the method of hierarchical frequency averaging, the prototypal sheep gene pool was reconstructed. The three-tiered analysis of diversity based on the ISSR fingerprinting data showed that 15.8% of variability was found between the breeds, 31.4% of variability was found between the populations within the breeds, and the diversity among the individuals within the populations constituted 52.8%.

A mathematical model of the combustion of a flat layer of methane hydrate is presented, which includes the continuity equations for the gas mixture, the conservation of the mass of each of its components, as well as the heat balance in the gas and gas hydrate layers. In addition, the system is supplemented by the conditions following the laws of conservation of mass and heat at the boundary of the “gas hydrate - gas” phase transition. The distributions of the concentration fields of the gas mixture, as well as the temperature fields in the gas hydrate and gas, are plotted.

The paper presents a mathematical model of dissociation of methane hydrate under thermal influence on a porous layer. The problem of influence of a heat source (hot liquid) on a porous layer of finite length initially saturated with methane hydrate is considered. Temperature distributions in the system at different times are constructed. The influence of the heat source temperature on the character of the phase transition boundary motion is investigated. A technological scheme is proposed, and on its basis a mathematical model is constructed that describes heating and simultaneous gas extraction into a combined well consisting of two coaxial pipes. The efficiency of the proposed method of gas production is analyzed.

The paper considers the problem of dissociation of methane gas hydrate saturating a porous medium of finite extent under the action of an external radiation source. The mathematical model includes the equations of continuity, heat inflow, and Darcy’s law, and is supplemented by the conditions of mass and heat balance on the discontinuity surface. In this case, we consider the case when the left boundary of a porous system is impervious to gas and heat flows, and the power of the source depends inversely on the coordinate of the phase transition front. Based on a computational algorithm developed using the method of catching the front in the grid node, the influence of the initial parameters of the reservoir on the maximum temperatures and pressures implemented in the system is studied. The influence of the power of the radiation source and the volume content of gas hydrate in the system on the intensity of its decomposition is also considered.

The article summarizes the results of numerical monitoring of the decomposition of gas hydrates in a high frequency electromagnetic field. The results of the numerical experience of the decay process are summarized. In addition, the distribution of temperature and pressure is presented, but in addition, the relationship with the coefficient of permeability. In this article, the features of decomposition of methane hydrate under the influence of microwave radiation are studied. It is shown that the values of temperature and pressure in the reservoir decrease with time and distance from the source of microwave radiation. The dependence of the expansion front coordinate on time for different values of the permeability coefficient is presented.

The formation of gas hydrate deposits on the inner surface of gas production equipment is a frequently occurring type of complication in gas production, leading to a significant decrease in the useful section of pipes and gas pipelines. The intensity of their formation can lead to a complete overlap of the lifting pipes and annular channels in the annulus in certain areas, which necessitates repair work to clean the wells of gas hydrates. Based on the analysis of methods for cleaning wells from gas hydrate deposits, it was revealed that in some cases one of the effective methods of preventing their formation and combating them is to use the energy of high-frequency and superhigh frequency electromagnetic fields. The article explores the processes of heating and decomposition of gas hydrate deposits in the wellbore. About 30% of the thermal energy released in the wellbore interacting with the electromagnetic field is consumed to heat the medium surrounding the well. The need for timely removal of the gas-water mixture formed in the annulus for the decomposition of gas hydrate along the entire length of the well is established.

Background Natural gas hydrates are of great scientific and practical interest. This is due to the fact that gas hydrates are natural reservoirs that accumulate large volumes of gas (methane) and water. Interest in the study of hydrate combustion is due to various factors: increased thermal efficiency for use in power engineering, greater hydrate stability, and the possibility of on-site combustion. Aims and Objectives Investigate the combustion process of methane hydrate in a closed space. Methods Math modeling. Results The case is considered when the gas region surrounding the hydrate is divided into two regions. In this case, the near region adjacent to the hydrate contains fuel (methane) and an oxidant to initiate the combustion process; there is no fuel in the far region. The presented system of basic equations includes the equations of momenta, mass conservation for the entire gas mixture, as well as for each of its components; heat flow equations (for gas hydrate and gas mixture). In addition, the presented system of equations is supplemented by the conditions for the balance of mass and heat at the decomposition boundary of the gas hydrate, as well as with the initial conditions and conditions at the boundaries of the closed space. The solution of the presented system was carried out by the method of large particles. On the basis of numerical solutions, it has been established that at low values of the transfer coefficients, stable combustion is observed and the maximum gas temperature is maintained approximately constant at 900 K. At high values of the transfer coefficients, the rate of hydrate decomposition increases. As a result, the intensity of methane combustion increases, which leads to a rapid consumption of oxygen and, as a consequence, the termination of the combustion process. It was found that with an increase in the initial oxygen concentration, the combustion time, as well as the maximum pressure in the volume, increase.

Background Many technological processes in the oil and gas industry are accompanied by the formation and deposition of gas hydrates both in the reservoir and in the systems of underground and surface equipment of oil and gas fields. In this case, the processes of hydrate formation lead to the release of latent heat of hydrate formation, which can lead to a significant increase in temperature in a porous medium. The mathematical model of the formation and decomposition of gas hydrates in a porous medium of infinite length was considered earlier. It was found that, depending on the initial and boundary conditions, the formation and decomposition of gas hydrate can occur both on the frontal surface and in an extended region. Aims and Objectives Consider a mathematical model of the formation of gas hydrate in a porous medium of finite length with the formation of an extended region of phase transitions. Methods Math modelling. Results The influence of the initial parameters, as well as the parameters at the boundary of the medium, on the evolution of the temperature fields in the reservoir is investigated. It is shown that the injection of cold gas leads to the heating of the formation, and it is the stronger, the higher the pressure of the injected gas.

Background Currently, the energy potential of natural gas hydrates is the main incentive for their comprehensive study. Estimates of the amount of gas contained in natural hydrates vary widely by different researchers, but they all agree that this amount is much higher than the existing and explored gas reserves. The mathematical modeling of the formation of gas hydrate during gas injection into a porous medium initially saturated with gas and ice was carried out earlier. It should be noted that the process of hydrate formation is considered for porous media of semi-infinite length in a self-similar approximation. However, all real formations have a sufficient length, but are still limited in size. Therefore, self-similar solutions turn out to be valid only for the initial times of the hydrate formation process, when the influence of the right boundary is not yet significant. Aims and Objectives: - to investigate the process of gas hydrate formation in a porous medium of finite length, initially saturated with methane and ice; - to consider the cases of hydrate formation on the frontal surface and in the extended area. Methods Math modeling. Results On the basis of the presented mathematical model, the problem of gas hydrate formation during gas (methane) injection into a porous layer of finite length, initially saturated with methane and ice, is considered. Cases where hydrate formation occurs both on the frontal surface and in an extended area have been investigated. It has been established that a part of the gas hydrate formed in an extended region can further dissociate, and an extended hydrate formation region can degenerate into a frontal surface.

Background Gas production from a gas hydrate reservoir is associated with phase transitions in the process of decomposition of a gas hydrate into liquid and gas and is implemented by various methods. The decomposition of gas hydrate occurs due to increase in temperature, depressurization (decrease in pressure), use of inhibitors, exposure by microwave electromagnetic radiation, etc. Aims and Objectives Aims and Objectives Research the process of gas hydrate decomposition in a radial model setting using the example of methane hydrate. Methods Math modeling. Results The article presents the results of numerical modeling of gas hydrates decomposition in a high-frequency electromagnetic field. The results of a numerical experiment of the decomposition process are presented, and the temperature and pressure distributions, as well as the dependence on the permeability coefficient, are shown. The distributions of temperature and pressure of the formation are also presented, the dependences of the position of the phase transition boundary on the parameters of the medium and the source of microwave radiation are studied.

Estimation of the state of the genetic diversity and the originality of the breed structure is required for the conservation and management of domestic breeds of agricultural animals. The Romanov breed of sheep from the leading breeding and gene pool farms in Yaroslavl oblast (Russia) is the object of our study. ISS R fingerprinting was used as a molecular method of the study of sheep gene pools. Forty-three DNA fragments were detected (25 and 18, respectively) by two primers ((AG)9C and (GA)9C). Of the discovered ISSR markers, 81% were polymorphic. The coefficient of genetic originality was for the first time used for the study of the specificity and originality of the Romanov-breed gene pool. Based on its values, the studied individuals were divided into five classes depending on the frequency of the ISSR fragment. The most original or the rarest, as well as typical genotypes, were singled out in the Romanov sheep gene pool. Use the obtained data on genetic originality was proposed as a means to increase the efficiency of selection and breeding during the breeding of autochthonous breeds of domesticated animal species.

Carbon cycling in Peruvian margin sediments (11° S and 12° S) was examined at 16 stations from 74 m on the inner shelf down to 1024 m water depth by means of in situ flux measurements, sedimentary geochemistry and modeling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates and benthic dissolved inorganic carbon fluxes decreased rapidly with water depth. Particulate organic carbon (POC) content was lowest on the inner shelf and at the deep oxygenated stations (< 5%) and highest between 200 and 400 m in the oxygen minimum zone (OMZ, 15–20%). The organic carbon burial efficiency (CBE) was unexpectedly low on the inner shelf (< 20%) when compared to a global database, for reasons which may be linked to the frequent ventilation of the shelf by oceanographic anomalies. CBE at the deeper oxygenated sites was much higher than expected (max. 81%). Elsewhere, CBEs were mostly above the range expected for sediments underlying normal oxic bottom waters, with an average of 51 and 58% for the 11° S and 12° S transects, respectively. Organic carbon rain rates calculated from the benthic fluxes alluded to a very efficient mineralization of organic matter in the water column, with a Martin curve exponent typical of normal oxic waters (0.88 ± 0.09). Yet, mean POC burial rates were 2–5 times higher than the global average for continental margins. The observations at the Peruvian margin suggest that a lack of oxygen does not affect the degradation of organic matter in the water column but promotes the preservation of organic matter in marine sediments.