bluuebunny/crossref_metadata_2025 huggingface dataset:
Local Solvability, Blow-up, and Hölder Regularity of Solutions to Some Cauchy Problems for Nonlinear Plasma Wave Equations: II. Potential Theory
Authors: Korpusov M. O. , Ovsyannikov E. A.
Published: April 2024

Volume and surface potentials arising in Cauchy problems for nonlinear equations in the theory of ion acoustic and drift waves in a plasma are considered, and their properties are examined. For the volume potential, an estimate is derived, which is used to prove a Schauder-type a priori estimate and Schauder-type estimates for weighted potentials.
Analysis of Mechanisms of Production Investment Stimulation in an Imperfect Capital Market Based on a Mathematical Model
Authors: Obrosova N. K. , Shananin A. A.
Published: April 2024

The problem of renewed market investment in the Russian real economy is closely related to the business environment state in the imperfect capital market in Russia and to the assessment of the profitability of investment projects. Difficulties in determining profitability in an imperfect monetary and credit system are associated with the significant discrepancy between the interest rates on deposits and loans and can be overcome by applying the Cantor–Lippman approach, which makes it possible to calculate the profitability of a pool of investment projects available to an investor. From the point of view of a production owner, market investment depends on the state of the business environment and competes with investment in consumption. The problem arises of estimating the profitability threshold at which private market investment is preferred to private consumption. We propose an approach to the solution of this problem in terms of a mathematical model of investment behavior of a production owner in an imperfect capital market. The model is formalized as an infinite-horizon optimal control problem with a state constraint. The solution of the problem is based on constructing a viscosity solution of the Hamilton–Jacobi–Bellman equation. It is shown that the investment strategy of a production owner can depend substantially on the business environment state. Based on the results of this study, an explanation is proposed for the transition from recovery growth to stagnation in the Russian economy in late 2007, which was accompanied by recession of investment activities in the manufacturing sector.
Sensitivity of Functionals of the Solution to the Variational Assimilation Problem to the Input Data on the Heat Flux for a Model of Sea Thermodynamics
Authors: Parmuzin E. I. , Shutyaev V. P.
Published: April 2024

For the mathematical model of the sea thermodynamics developed at the Marchuk Institute of Numerical Mathematics, Russian Academy of Sciences, the problem of variational assimilation of observational data in order to recover heat fluxes on the sea surface is considered. The sensitivity of functionals of the solution to the input data on the heat flux in this problem is studied, and the results of numerical experiments for the model of Black Sea dynamics are presented.
On Critical Exponents for Weak Solutions of the Cauchy Problem for a (2 + 1)-Dimensional Nonlinear Composite-Type Equation with Gradient Nonlinearity
Authors: Korpusov M. O. , Matveeva A. K.
Published: April 2024

The Cauchy problem for a model nonlinear equation with gradient nonlinearity is considered. We prove the existence of two critical exponents, and, such that this problem has no local-in-time weak (in some sense) solution for , while such a solution exists for , but, for , there is no global-in-time weak solution.
Krasovskii Institute of Mathematics and Mechanics, Ural Branch, Russian Academy of Sciences
Authors: Shevaldin V. T.
Published: April 2024

Explicit formulas are given for interpolating parabolic splines on a number line interval constructed by J. Favard in 1940. For approximations by these splines in the Sobolev classof twice differentiable functions, estimates for the norm of the second derivative and the approximation error in the uniform metric are established.
Optimization of Control and Parameters in Systems with Phase Constraints
Authors: Tyatyushkin A. I.
Published: April 2024

For an optimal control problem with constraints on phase coordinates, an iterative method for finding a numerical solution is considered, based on reduction to a finite-dimensional problem and applying to it a sequential linearization algorithm using a modified Lagrange function. To solve linear auxiliary problems at iterations of the method, the reduced gradient method is used. The efficiency of taking into account phase constraints in the calculation of optimal control is illustrated by the numerical solution of problems from the field of aerodynamics and robotics.
Conditional Gradient Method for Optimization Problems with a Constraint in the Form of the Intersection of a Convex Smooth Surface and a Convex Compact Set
Authors: Chernyaev Yu. A.
Published: April 2024

The conditional gradient method is generalized to nonconvex sets of constraints representing the set-theoretic intersection of a convex smooth surface and a convex compact set. Necessary optimality conditions are studied, and the convergence of the method is analyzed.
Inverse Problems for the Helmholtz Equation on Finding the Right-Hand Side with Nonlocal Integral Observation
Authors: Sabitov K. B.
Published: April 2024

The paper presents formulations of inverse problems for the Helmholtz equation on finding its right-hand side with a Samarskii–Ionkin-type additional integral condition and the justification of their well-posedness in the Hadamard sense in the class of regular solutions. The uniqueness of solutions of the formulated problems is proved on the basis of integral identities. Solutions of the problem are found in explicit form by the methods of separation of variables and integral equations.
On the Set of Stable Matchings in a Bipartite Graph
Authors: Karzanov A. V.
Published: April 2024

The topic of stable matchings (marriages) in bipartite graphs gained popularity beginning from the appearance of the classical Gale and Shapley work. In this paper, a detailed review of selected and other related statements in this field that describe structured, polyhedral, and algorithmic properties of such objects and their sets accompanied by short proofs is given.
On the Uniqueness of Solutions to Systems of Linear Algebraic Equations Resulting from the Reduction of Linear Inverse Problems of Gravimetry and Magnetometry: a Local Case
Authors: Kolotov I. I. , Lukyanenko D. V. , Stepanova I. E. , Yagola A. G.
Published: April 2024

The paper considers issues of unique solvability of systems of linear algebraic equations to which many inverse problems of geophysics are reduced as a result of discretization. Examples of degenerate and nondegenerate systems of different dimensions arising from the interpretation of gravity and magnetometric data are given.
Aggregation and Decomposition of Systems of Partial Differential Equations and Control Systems with Distributed Parameters
Authors: Elkin V. I.
Published: April 2024

The aggregation (consolidated, simplified representation) of systems of partial differential equations and control systems with distributed parameters is considered. Decomposition conditions based on aggregation are obtained.
Singularity Formation in an Incompressible Boundary Layer on an Upstream Moving Wall under Given External Pressure
Authors: Bezrodnykh S. I. , Zametaev V. B. , Chzhun Te Ha
Published: April 2024

The two-dimensional laminar flow of a viscous incompressible fluid over a flat surface is considered at high Reynolds numbers. The influence exerted on the Blasius boundary layer by a body moving downstream with a low velocity relative to the plate is studied within the framework of asymptotic theory. The case in which a small external body modeled by a potential dipole moves downstream at a constant velocity is investigated. Formally, this classical problem is nonstationary, but, after passing to a coordinate system comoving with the dipole, it is described by stationary solutions of boundary layer equations on the wall moving upstream. The numerically found solutions of this problem involve closed and open separation zones in the flow field. Nonlinear regimes of the influence exerted by the dipole on the boundary layer with counterflows are calculated. It is found that, as the dipole intensity grows, the dipole-induced pressure acting on the boundary layer grows as well, which, after reaching a certain critical dipole intensity, gives rise to a singularity in the flow field. The asymptotics of the solution near the isolated singular point of the flow field is studied. It is found that, at this point, the vertical velocity grows to infinity, viscous stress vanishes, and no solution of the problem exists at higher dipole intensities.
Numerical Analysis of Rarefied Gas Flow through a System of Short Channels
Authors: Voronich I. V. , Titarev V. A.
Published: April 2024

The S-model kinetic equation is used to study the rarefied gas flow from a high-pressure tank to a low-pressure one through a flat membrane with a finite number of pores. The kinetic equation is solved numerically using a second-order accurate implicit conservative method implemented in the in-house code Nesvetay. For transitional and continuum flow regimes, numerical solutions of the compressible Navier–Stokes equations are obtained. The gas flow rate through the system of pores and the forces acting on the membrane bars are investigated as functions of the Knudsen number (Kn) at a pressure ratio of 2 : 1 in the tanks. The features of the flow field near the membrane and away from it are described.
Stability and Error Estimates of High Order BDF-LDG Discretizations for the Allen–Cahn Equation
Authors: Yan Fengna , Cheng Ziqiang
Published: April 2024

We construct high order local discontinuous Galerkin (LDG) discretizations coupled with third and fourth order backward differentiation formulas (BDF) for the Allen–Cahn equation. The numerical discretizations capture the advantages of linearity and high order accuracy in both space and time. We analyze the stability and error estimates of the time third-order and fourth-order BDF-LDG discretizations for numerically solving Allen–Cahn equation respectively. Theoretical analysis shows the stability and the optimal error results of theses numerical discretizations, in the sense that the time step τ requires only a positive upper bound and is independent of the mesh size h. A series of numerical examples show the correctness of the theoretical analysis. Comparison with the first-order numerical discretization illustrates that the high order BDF-LDG discretizations show good performance in solving stiff problems.
On One Method for Calculating Nonstationary Heat Transfer between a Gas Flow and a Solid Body
Authors: Zhukov V. T. , Novikova N. D. , Feodoritova O. B.
Published: April 2024

A method for calculating the nonstationary thermal interaction between a viscous gas flow and a solid body is presented. The method consists in direct joint integration over time of the equations of gas dynamics of a multicomponent mixture and the heat equation in a solid on multi-block unstructured meshes. To calculate one time step, the system of governing equations is split into hyperbolic and parabolic subsystems. The numerical method provides approximation of the matching condition (continuity of temperature and the normal component of the heat flux) at the interface between gas and solid and is efficient for nonstationary calculations. The comparison with the analytical solution of the model problem of the interaction of a high-speed flow and a heated plate confirm the efficiency of the method.
Properties of Degenerate Systems of Linear Integro-Differential Equations and Initial Value Problems for These Equations
Authors: Chistyakov V. F , Chistyakova E. V
Published: April 2024

We consider systems of higher order integro-differential equations in which the matrix multiplying the highest derivative of the unknown vector function is identically singular in the domain where the system is considered. We give criteria for the solvability of such systems and initial value problems for these systems as well as examples illustrating the theoretical results.
On the Fundamental Solution of a Parabolic Equation with Dini Continuous Coefficients
Authors: Baderko E. A , Semenov K. V
Published: April 2024

We consider a parabolic equation in one spatial variable with Dini continuous coefficients. For this equation, the existence of a classical fundamental solution is proved and estimates are given. The condition on the nature of the continuity of the leading coefficient of the equation for the existence of a fundamental solution is sharp.
Well-Posedness of the Generalized Samarskii–Ionkin Problem for Elliptic Equations in a Cylindrical Domain
Authors: Kozhanov A. I , Dyuzheva A. V
Published: April 2024

We study the well-posedness of some analogs of the nonlocal Samarskii–Ionkin problem for second-order elliptic equations in Sobolev spaces. For the problems in question, existence and uniqueness theorems are proved for regular solutions, i.e., solutions that have all generalized Sobolev derivatives occurring in the corresponding equation. Some spectral problems for elliptic equations with the nonlocal Samarskii–Ionkin condition are studied.
On a Nonclassical Eigenvalue Problem with Nonlinearizable Solutions
Authors: Valovik D. V , Martynova V. Yu
Published: April 2024

We study a nonlinear eigenvalue problem of a special form arising in electrodynamics. The problem is posed for a system of two equations with boundary conditions of the first kind and two additional local conditions. There is one spectral parameter in the problem, and two more parameters, which are subject to an additional constraint, occur in the above-mentioned local conditions. Thus, there are two unknown parameters in the problem: one is the spectral parameter, and the other is some additional parameter, chosen so as to ensure that there exists a nontrivial solution of the problem in question. The existence of nonlinearizable solutions of the problem is proved.
On the Study of Robust Exponential Stability of Continuous- and Discrete-Time Systems
Authors: Antonovskaya O. G
Published: April 2024

A technique for obtaining sufficient conditions for the robust exponential stability of a parametrically uncertain system is proposed. This technique is used to study both continuousand discrete-time parametrically uncertain systems. For a common Lyapunov function we take a positive definite quadratic form that is a Lyapunov function of the system for a specific parameter value and satisfies some constraints on the first derivative (first difference). The application of our technique is illustrated by specific examples.
Initial–Boundary Value Problem for Flows of a Fluid with Memory in a 3D Network-Like Domain
Authors: Baranovskiy E. S
Published: April 2024

We consider an initial–boundary value problem for an integro-differential system that describes 3D flows of a non-Newtonian fluid with memory in a network-like domain. The problem statement uses the Dirichlet boundary conditions for the velocity and pressure fields as well as Kirchhoff-type transmission conditions at the internal nodes of the network. A theorem on the existence and uniqueness of a time-continuous weak solution is proved. In addition, an energy equality for this solution is derived.
On the Fundamental Solution Matrix of the Plane Anisotropic Elasticity Theory
Authors: Vyong Chan Kuang , Soldatov A. P
Published: April 2024

An explicit expression (in polar coordinates) for the fundamental solution matrix of the Lamé system of the plane anisotropic theory of elasticity is given. It is shown that the operator of convolution with this matrix in a finite domain with Lyapunov boundary is bounded in the Hölder spaces. A similar result is also established for an infinite domain in the corresponding weighted Hölder spaces (with a power-law behavior at infinity).
Ob opredelenii koeffitsientov kvadratichnoy funktsii Lyapunova s zadannymi svoystvami v sluchae kratnykh korney kharakteristicheskogo uravneniya
Authors: Antonovskaya O. G
Published: April 2024

For continuous and discrete linear autonomous systems, we discuss the possibility of choosing the coefficients of the quadratic Lyapunov function that ensure the validity of the condition of sign-negativity of its first derivative (first difference) with a given margin in the case of multiple roots of the characteristic equation.
Approksimatsiya resheniya obratnoy zadachi dlya singulyarno vozmushchennoy sistemy uravneniy v chastnykh proizvodnykh
Authors: Denisov A. M
Published: April 2024

We consider an initial–boundary value problem for a singularly perturbed system of partial differential equations. We pose an inverse problem of determining an unknown initial condition based on additional information about the solution of the initial–boundary value problem. It is proved that using the expansion of the solution of the initial–boundary value problem in the small parameter, one can obtain solutions approximating the solution of the inverse problem with order O(e)or O(e).
Yavno-neyavnye skhemy rascheta dinamiki uprugovyazkoplasticheskikh sred s malym vremenem relaksatsii
Authors: Golubev V. I , Nikitin I. S , Burago N. G , Golubeva Yu. A
Published: April 2024

We consider the dynamic behavior of elastoviscoplastic media under the action of an external load. For the general case of a nonlinear viscosity function describing high-speed hardening, we construct an explicit–implicit calculation scheme of the second order of approximation that permits one to obtain a numerical solution of the original semilinear hyperbolic problem. A distinctive feature of this approach is that it does not use the method of splitting by physical processes. Despite this, an explicit computational algorithm was obtained that allows efficient implementation on modern computing systems.
Obobshchennye resheniya pervoy kraevoy zadachi dlya differentsial'no-raznostnogo uravneniya v divergentnom vide na intervale konechnoy dliny
Authors: Skubachevskiy A. L , Ivanov N. O
Published: April 2024

We consider the Dirichlet problem for a second-order differential–difference equation in divergence form with variable coefficients on a finite interval Q = (0, d). Conditions on the right-hand side of the equation ensuring the smoothness of the generalized solution on the entire interval are studied. It is proved that the generalized solution of the problem belongs to the Sobolev space W22(Q) if the right-hand side is orthogonal in the space L2(Q) to finitely many linearly independent functions
Variatsionnye metody resheniya zadach, svyazannykh s iskusstvennym intellektom
Authors: Babushkin M. V , Tertychnyy-dauri V. Yu
Published: April 2024

We introduce the concepts of a learning algorithm, an objective function, a recognition system, a class of patterns, a training set, a reward algorithm, a finitely convergent algorithm, an adaptive control system, a control goal, control tactics, adaptation time, etc., related to the problem of artificial intelligence in the processes of learning and adaptation. The general problem of self-learning (unsupervised learning)—about the separation of sets—in terms of the classical calculus of variations is posed. The generality of the problem is due to the introduction of an additional time variable into the analysis. The problem is solved by determining extremal conditions under which the minimization of the overall average risk functional is achieved. Problems corresponding to nonfixed and fixed time intervals are considered. For these two cases, expressions are found for calculating variations in cost functionals. Necessary conditions are indicated for determining the extremal values of the self-learning process (separation of classes of a set of patterns) in time.
Lineynaya zadacha gruppovogo presledovaniya s drobnymi proizvodnymi, prostymi matritsami i raznymi vozmozhnostyami igrokov
Authors: Petrov N. N , Machtakova A. I
Published: April 2024

In a finite-dimensional Euclidean space, we consider the problem of pursuit by a group of pursuers of one evader, which is described by a system of equations with a Caputo derivative of order a , where the sets of feasible controls are convex compact sets. We obtain sufficient conditions for the solvability of pursuit and evasion problems, in the study of which the method of resolving functions is used.
K voprosu o chislennom reshenii nekonservativnykh giperbolicheskikh sistem uravneniy
Authors: Polekhina R. R , Alekseev M. V , Savenkov E. B
Published: April 2024

Issues related to the lack of convergence in the application of formally path-conservative difference schemes for solving nonconservative hyperbolic systems of equations are numerically investigated. This problem is central in constructing well-posed difference schemes for solving this class of problems. The basic concepts of the theory of nonconservative hyperbolic systems of equations and the corresponding problems of constructing difference schemes for their solution are outlined. A variant of the HLL method is proposed that allows using an arbitrary explicitly specified path. For a model system of Burgers equations, the shock adiabates and paths corresponding to the viscous regularization of a system of a given form are explicitly calculated. The reasons for the lack of convergence of numerical solutions of exact ones in the case of incorrect application of the corresponding algorithms are analyzed. It is shown that, at least in the particular case considered, a variant of the HLL method that is formally conservative along the way gives the correct solution of the problem.
Comparing the Spectra of Oscillation Exponents of a Nonlinear System and the First Approximation System
Authors: Stash A. Kh
Published: April 2024

We study the oscillation exponents of differential systems. It is established that there is no dependence between the spectra of oscillation exponents of a nonlinear system and the system of its first approximation; namely, a two-dimensional nonlinear system is constructed such that the spectra of oscillation exponents of its restriction to any open neighborhood of zero on the phase plane consist of all rational numbers in the interval and the spectra of the linear system of its first approximation consist of only one element.
Classical Solution of the Second Mixed Problem for the Telegraph Equation with a Nonlinear Potential
Authors: Korzyuk V. I. , Rud'ko Ya. V.
Published: April 2024

For the telegraph equation with a nonlinear potential, we consider a mixed problem in the first quadrant in which the Cauchy conditions are specified on the spatial semiaxis and the Neumann condition is set on the temporal semiaxis. The solution is constructed by the method of characteristics in an implicit analytical form as a solution of some integral equations. The solvability of these equations is studied, as well as the dependence of the solutions on the smoothness of the initial data. For the problem under consideration, the uniqueness of the solution is proved and conditions are established under which a classical solution exists. If the matching conditions are not met, then a problem with conjugation conditions is constructed, and if the data is not smooth enough, then a mild solution is constructed.
Gellerstedt Problem with a Nonlocal Oddness Boundary Condition for the Lavrent’ev–Bitsadze Equation
Authors: Moiseev T. E
Published: April 2024

We study the Gellerstedt problem for the Lavrent’ev–Bitsadze equation with the oddness boundary condition on the boundary of the ellipticity domain. All eigenvalues and eigenfunctions are obtained in closed form. It is proved that the system of eigenfunctions is complete in the elliptic part of the domain and incomplete in the entire domain. The unique solvability of the problem is also proved; the solution is written in the form of a series if the spectral parameter is not equal to an eigenvalue. For the spectral parameter coinciding with an eigenvalue, solvability conditions are obtained under which the family of solutions is found in the form of a series. A condition for the solvability of the problem depending on the eigenvalues is obtained. The constructed analytical solutions can be used efficiently in numerical modeling of transonic gas dynamics problems.
Solvability of Linear Differential Equations
Authors: Mokeychev V. S. , Sidorov A. M.
Published: April 2024

We propose a new approach to the solvability of ordinary as well as partial differential equations in the theory of linear differential equations and also in the theory of integral equations.
Bounded Real Lemma for the Anisotropic Norm of Time-invariant Systems with Multiplicative Noises
Authors: Yurchenkov A. V. , Belov I. R.
Published: April 2024

We consider a discrete-time-invariant system with multiplicative noise with implementation in the state space. The exogenous disturbance is chosen from the class of time-invariant ergodic sequences of nonzero colorness. We consider the level of mean anisotropy of the exogenous disturbance to be bounded by a known value. Conditions for the anisotropic norm to be bounded by a given number are obtained in terms of solving a matrix system of inequalities with a convex constraint of a special type. It is demonstrated how, on the basis of the obtained conditions, to construct a static state control that ensures the minimum value of the anisotropic norm of the system enclosed by this control.
On the Smoothness of the Poisson Potential for Second-Order Parabolic Systems on the Plane
Authors: Baderko E. A. , Fedorov K. D.
Published: April 2024

We consider the solution of the Cauchy problem in a strip on the plane for a homogeneoussecond-order parabolic system. The coefficients of the system satisfy the doubleDini condition. The initial function is continuous and bounded along with its first and secondderivatives. Using the Poisson potential, the nature of the smoothness of this solution is studiedand the corresponding estimates are proved.
Existence of Sub-Lorentzian Longest Curves
Authors: Sachkov Yu. L.
Published: April 2024

Sufficient conditions for the existence of optimal trajectories in general optimalcontrol problems with free terminal time as well as in sub-Lorentzian problems are obtained.
On the Existence of Feedback Control for One Fractional Voigt Model
Authors: Zvyagin A. V. , Kostenko E. I.
Published: April 2024

We study the feedback control problem for a mathematical model that describesthe motion of a viscoelastic fluid with memory along the trajectories of the velocity field. Weprove the existence of an optimal control that delivers a minimum to a given bounded and lowersemicontinuous cost functional.
Mass-spectra of new heterocycles: XXIV. Electron impact and chemical ionization study of N-[3-alkoxyand 3-(1H-pyrrol-1-yl)-2-thienyl]imidothiocarbamates
Authors: Klyba L. V , Sanzheeva E. R , Nedolya N. A , Tarasova O. A
Published: April 2024

The behavior of a wide range of previously unknown N -(2-thienyl)imidothiocarbamates synthesized in a single preparative step from heterosubstituted allenes (methoxy-, 1-ethoxyethoxy- and 1 H -pyrrol-1-ylallenes) and aliphatic, cycloaliphatic, and aromatic isothiocyanates was studied under conditions of electron (70 eV) and chemical (reagent gas - methane) ionization. Under the electron impact, the studied compounds form an unstable molecular ion, the main direction of fragmentation of which is associated with the breaking of the C-N bond in the imidoformamide fragment with charge localization at the imine nitrogen atom. A similar decay channel of a molecular ion is also observed in the chemical ionization mass spectra of the studied compounds. In this case, characteristic, but low-intensity ions in the electron ionization spectra of N -(3-methoxy-2-thienyl)imidothiocarbamates become dominant in the chemical ionization spectra. In the chemical ionization spectra of N -[3-(1 H -pyrrol-1-yl)-2-thienyl]imidothiocarbamates, the maximum intensity peak belongs to the [ M - SMe]+ ion. For N -[3-(1-ethoxyethoxy)-2-thienyl]imidothiocarbamate, the peak of the ion formed upon successive elimination of ethoxyethene and methanethiol molecules from the [ M + H]+ ion has the maximum intensity.
Push-pull systems based on 2,4,6-triaryl pyrimidines. 2,4-diaryl-6- and 2-aryl-4,6-bis{4-[(E)-2-arylvinyl]phenyl}pyrimidines
Authors: Harutyunyan A. A , Safaryan M. S , Dilanyan S. V , Panosyan H. A , Danagulyan G. G
Published: April 2024

Previously undescribed 2,4,6-triarylpyrimidines were synthesized by condensation of benzamidine and 4-(methyl-, 4-butoxy)benzamidine hydrochlorides with ( E )-1,3-diaryl-2-propen-1-ones in alcohol in the presence of KOH. The latter were reacted with ( E )- N -(2-chlorophenyl)-1-arylmethanimines in the KOH/LiH/DMF system to give 2,4-diaryl-6- and 2-aryl-4,6-bis{4-[( E )-2-arylvinyl]phenyl}-pyrimidines.
Multicomponent synthesis of functionalized 2-amino-4H-pyrans initiated by the Knoevenagel reaction
Authors: Dyachenko I. V , Dyachenko V. D , Dorovatovskii P. V , Khrustalev V. N , Nenajdenko V. G
Published: April 2024

The multicomponent condensation of aldehydes, malononitrile derivatives, 1,3-dicarbonyl compounds of the carbo- and heterocyclic series, and alkyl halides has been studied. The transformation is initiated by the Knoevenagel reaction and leads to the formation of functionally substituted condensed 2-amino- 4 H-pyrans. The structure of a number of products was studied by X-ray diffraction.
Synthesis of new 1,3,4-oxadiazole and 1,2,3-triazole derivatives based on thieno[3,2-b]pyrrolecarboxylic acid
Authors: Torosyan S. A , Nuriakhmetova Z. F , Gimalova F. A , Miftakhov M. S
Published: April 2024

Starting from 4-benzylthieno[3,2- b ]pyrrole-5-carboxylic acid hydrazide and 4-(2-propyn-1-yl)thieno[3,2- b ]pyrrole-5-carboxylic acid methyl ester new 1,3,4-oxadiazole and 1,2,4-triazole derivatives were obtained.
Synthesis of 1-(adamantan-1-yl)propan-1,2-diamine and chiral ligands based thereon
Authors: Mankova P. A , Reznikov A. N , Shiryaev V. A , Tkachenko I. M , Klimochkin Y. N
Published: April 2024

Racemic 1-(adamantan-1-yl)propan-1,2-diamine which was resolved with l-malic acid was obtained from trans-2-(adamantan-1-yl)-3-methylaziridine. The isolated (1 S ,2 R )-isomer was derivatized with benzyl. Enantiomeric excess of (2 S ,3 R )-2-(adamantan-1-yl)-3-methyl-5,6-diphenyl-2,3-dihydropyrazine was determined by HPLC. (4 S ,5 R )-4-(Adamantan-1-yl)-5-methylimidazolidine-2-thione was synthesized by the reaction of (1 S ,2 R )-diamine with carbon disulfide; absolute configuration was determined by X-ray diffraction analysis. Ligands were synthesized on the basis of racemic and chiral (1 S ,2 R )-1-(adamantan-1-yl)propan-1,2-diamines. The catalytic activity complexes were studied using Michael, Henri and epoxidation model reactions. For the model reaction of Henri stereodivergence was noted when using ligands of a similar structure.
Synthesis of fluoroalkyl and fluoroaryl substituted hexahydropyrimidines
Authors: Gibadullina N. N , Dokichev V. A
Published: April 2024

The data on the synthesis of fluoroalkyl and fluoroaryl substituted hexahydropyrimidine derivatives from the moment of their first mention are systematized. Predominantly one-pot multicomponent synthesis methods, including catalytic ones, are considered. The effect of the nature of the catalyst, starting reagents, and synthesis conditions on the yield and composition of the resulting products is discussed, and the biological activity of some derivatives is also shown.
The synthesis of thioglucoside and their tetracyclic conjugate based on 6-bromo-1,4-naphthoquinone
Authors: Polonik S. G , Popov R. S , Makhankov V. V , Sabutskii Y. E
Published: April 2024

A bromine-containing naphthoquinone-carbohydrate conjugate was obtained for the first time by intramolecular condensation of 3-acetylthioglucoside of 6-bromo-2-methoxy-1,4-naphthoquinone under sodium methoxide/ methanol treatment. It has been established that the heterocyclization reaction is accompanied by the substitution of the thioglucoside substituent by the methoxyl group and the formation of an isomeric conjugate.
Four-component condesation of ethyl acetoacetate, phenylglyoxal hydrate, barbituric acid and primary amines
Authors: Andin A. N. , Kukharev A. V.
Published: April 2024

By four-component condensation of ethyl acetoacetate, phenylglyoxal hydrate, barbituric acid and primary amines, polysubstituted pyrroles containing a barbituric acid fragment were obtained. In some cases, minor products of three-component condensation of phenylglyoxal hydrate, barbituric acid and amines have been isolated.
Theoretical study of electronic structure and ionization spectrum of γ-pyrone
Authors: Trofimov A. B , Iakimova E. K , Gromov E. V , Skitnevskaya A. D
Published: April 2024

The electronic structure and ionization spectrum of γ-pyrone (4 H -pyran-4-one) were studied using the third-order algebraic-diagrammatic construction method for a one-particle Green’s function [IP-ADC(3)] and a number of other high-level quantum chemical methods. The results of the calculations are used to interpret the recently obtained photoelectron spectra. A number of new assignments are proposed concerning the nature of the photoelectron maxima of γ-pyrone above 12 eV, where, according to our calculations, there is a significant violation of the single-electron ionization picture due to electron correlation effects. The results obtained significantly change the interpretation of the spectrum available in the literature.
Oxidative triflamidation of allyl cyanide in nitrile solutions
Authors: Ganin A. S. , Sobyanina M. M. , Moskalik M. Yu. , Shainyan B. A.
Published: April 2024

The reaction of triflamide with allyl cyanide in benzonitrile and isobutyronitrile solutions in the presence of NBS has been studied. In both cases, the corresponding amidines - the products of the solvent incorporation are formed. In benzonitrile, depending on the reaction conditions, the isomeric N -(2-bromo-3-cyanopropyl)- N '-(triflyl)benzamidine and N -(1-bromo-3-cyanoprop-2-yl)- N '-(triflyl)benzamidine were obtained in various ratio. From the reaction in isobutyronitrile, N -(2-bromo-3-cyanopropyl)- N '-(triflyl)isobutyramidine and the product of diamination, N -[3-cyano-1-(triflamido)propyl]isobutyramide were isolated.
Synthesis and reactions of allylic azides of the adamantane series
Authors: Leonova M. V. , Baimuratov M. R. , Klimochkin Yu. N.
Published: April 2024

A mixture of nucleophilic substitution product and isomeric azide resulting from [3,3]-sigmatropic rearrangement was obtained by interaction of allyl bromides of adamantane series with sodium azide. Epoxidation reactions of allylic azides of the adamantane series were investigated. The reduction of the obtained trans -2-(adamantan-1-yl)-3-(azidomethyl)oxirane with lithium alumohydride synthesized ( S *)-(adamantan-1-yl)[( S *)-aziridin-2-yl]methanol which, when heated with hydrochloric acid, gives the product of the aziridine ring opening is (1 S *,2 R *)-1-(adamantan-1-yl)-3-chloro-1-hydroxypropan-2-amino chloride.
TEMPORAL AND SPATIAL PATTERNS OF PERMAFROST PHENOMENA ALONG OPERATED RAILROAD IN THE SOUTHERN PART OF BOLSHEZEMELSKAYA TUNDRA UNDER A CHANGING CLIMATE
Authors: Gorbunova A. A. , Zaripova G. Z. , Isaev V. S. , Manskii V. N. , Sobin R. V. , Sergeev D. O. , Bezdelova A. P.
Published: April 2024

As a result of monitoring observations, it was found that the frequency of subsidence in different sections of the railway embankment in different years is associated with different engineering and geological conditions and leading cryogenic processes. It requires the special geocryological zoning of the territory adjacent to the railway to develop an engineering protection strategy. The criteria for ranking areas with embankment settlements according to their hazard degree, which are divided according to spatial and temporal characteristics are proposed. It was revealed that the long-term climate changes lead to a regional change in geocryological conditions (primarily the temperature regime of soil). The extreme climatic events and variable technogenic loads cause activation or attenuation of cryogenic processes.
INFLUENCE OF THE TECTONIC KNOTS IN THE NORTH OF THE RUSSIAN PLATE ON THE ENVIRONMENT STATE AT THE MICROLEVEL (BY THE EXAMPLE OF THE CONTENT OF ASCORBIC ACID IN BLUBERRY AND COWBERRY FRUITS)
Authors: Staritsyn V. V. , Kutinov Yu. G. , Polyakova E. V. , Chistova Z. B. , Mineev A. L.
Published: April 2024

The study is an addition to a series of articles on the results of monitoring studies on the impact of tectonic knots on the state of the environment in the region. The knots of tectonic dislocations are a link between the abiotic (geological) and biotic environments, and have a significant impact on the state of vegetation cover, both at the macro and micro levels. This article shows the regularity of the content of ascorbic acid (vitamin C) in blueberries and cowberries, depending on their spatial location within the tectonic knot. It was revealed that the concentrations of vitamin C in berries selected in the center and on the periphery of tectonic knots differ. For example, its content in blueberries from the center of the Kholmogory tectonic knot is 37% higher than in berries from the periphery of the same knot. In the fruits of blueberries from the center of the Plesetsk tectonic knot – by 59%, and in cowberries – by 62% more, compared with the periphery. In the fruits of cowberries from the center of the Velsko-Ustyansky tectonic knot – 58% more. These knots differ from each other in geomorphometric, geological, tectonic factors, etc., which allows us to conclude that deep factors influence the state of the environment in general and the concentration of vitamin C in blueberries and cowberries in particular.
BACKGROUND GEOECOLOGICAL CONDITIONS OF ELKON GOLD-URANIUM ORE REGION
Authors: Mironova M. O.
Published: April 2024

The Elkon ore region is located in the southern part of Sakha Republic (the largest federal subject of the Russian Federation). Elkon gold-uranium fields have the richest deposits of uranium ore, but they have not been developed. Although the natural landscapes of mountain taiga are already changed due to about-century-long geological exploration, we have the last chance to fix the environmental conditions before the start of developing. The paper deals with the characteristics of distribution of radionuclides and element in soils, plants and water of El’kon region and is based on field works performed in 2007–2008 (immediately after the decision on exploration). The Elkon horst is the part of Aldan Shield, an exposed basement of the Siberian craton not covered by the latest sediments. The uranium mineralization is confined to igneous Mesozoic complexes. Weathering and erosion cause dispersion halo of elements and radionuclides which may become probable pollutants. The studied area is divided into four geological formations, but soil probes reveal no distinction in geochemistry specialization. So landscapes were divided into three groups by level, slope exposition and vegetation condition. Each group was measured by couple of samples. The main migration features were assessed by the distribution of elements and radionuclides (some local peaks were found for 90Sr, As, Th, and Mo). The As, Pb (rarely Mn, Hg) contamination of soils is proved. The main co-locations were computated for soils. The total contamination was estimated acceptable to moderate rates, therefore, there were found local high-polluted areas in dump zones. The combined database could be used as a reference point for further environmental research.
STUDY OF THE IN VIVO FUNCTIONAL ROLE OF MUTATIONS IN THE BTB DOMAIN OF THE CP190 PROTEIN OF DROSOPHILA MELANOGASTER
Authors: Fedotova A. A. , Georgiev P. G. , Bonchuk A. N.
Published: April 2024

The Drosophila transcription factor СР190 is one of the key proteins that determine the activity of housekeeping gene promoters and insulators. CP190 has an N-terminal BTB domain that allows for dimerization. Many of known Drosophila architectural proteins interact with the hydrophobic peptide-binding groove in the BTB domain, which is supposed to be one of the mechanisms for recruiting CP190 to regulatory elements. To study the role of the BTB domain in the interaction with architectural proteins, we obtained transgenic flies expressing CP190 variants with mutations in the peptide-binding groove, which disrupts their interaction with architectural proteins. As a result of the studies, it was found that mutations in the BTB domain do not affect binding of the CP190 protein to polytene chromosomes. Thus, our studies confirm the previously obtained data that CP190 is recruited to regulatory elements by several transcription factors interacting in addition to BTB with other CP190 domains.
PHOSPHOLIPID COMPOSITION OF FINGERLINGS OF ATLANTIC SALMON SALMO SALAR DURING GROWTH AND DEVELOPMENT IN AQUACULTURE: THE EFFECT OF DIFFERENT LIGHTING AND FEEDING REGIMES
Authors: Murzina S. A. , Provotorov D. S. , Voronin V. P. , Manoilova D. I. , Kuritcyn A. E. , Pekkoeva S. N. , Nemova N. N.
Published: April 2024

The effect of different modes of feeding and lighting (natural and continuous) on the phospholipid composition of Atlantic salmon fingerlings reared under commercial aquaculture in the summer-autumn period in North Ossetia-Alania was studied. Qualitative and quantitative determination of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, lysophosphatidylcholine, sphingomyelin was carried out by high performance liquid chromatography. A decrease (September-November) The content of the studied phospholipids in fingerlings decreased, which should be considered primarily as a biochemical adaptation of development, preparation of juveniles for the upcoming smoltification. The effects of lighting and feeding regime on phospholipid composition were found mainly in fish reared under constant lighting and 24/7 feeding and fish reared under natural light and feeding during daylight hours, however, the observed changes were not specific to a particular experimental group of fish in the framework of this study.
COMPARATIVE DETERMINATION OF NATURAL ANTIBODIES FOR THE ASSESSMENT OF THE CARDIOVASCULAR SYSTEM AND THE LEVEL OF HUMAN
Authors: Myagkova M. A. , Bobrova Z. V. , Orlova E. А. , Petrochenko S. N.
Published: April 2024

A comparative analysis of natural antibodies to β-endorphin, angiotensin, dopamine, serotonin, parameters of the cardiovascular system and anxiety levels was carried out for 241 athletes of various qualifications and sports. The obtained indicators of the cardiovascular system were compared with reference values. A significant increase in the level of natural antibodies to angiotensin was established for all groups of athletes. In the case of dopamine, serotonin, these differences are associated with the qualification of the athlete, for β-endorphin, differences in the level of the indicator depending on the sport were found. A group of individuals with high levels of situational and personal anxiety was found among highly qualified athletes. An increase in blood pressure in athletes of cyclic sports and martial arts is adaptive, and in athletes of speed-strength sports it leads to a change in the walls of the myocardium. As a result of the study, the possibility of a comprehensive determination of natural antibodies and functional indicators as diagnostic markers for assessing the state of the human cardiovascular system has been shown.
IDENTIFICATION OF SIGNIFICANT RNA-BINDING PROTEINS IN THE PROCESS OF CD44 SPLICING USING THE BOOSTED BETA REGRESSION ALGORITHM
Authors: Novosad V. O.
Published: April 2024

The expression of RNA-binding proteins and their interaction with the spliced pre-mRNA are the key factors in determining the final isoform profile. Transmembrane protein CD44 is involved in differentiation, invasion, motility, growth and survival of tumor cells, and is also a commonly accepted marker of cancer stem cells and epithelial-mesenchymal transition. However, the functions of the isoforms of this protein differ significantly. In this paper, we developed a method based on the boosted beta regression algorithm for identification of the significant RNA-binding proteins in the splicing process by modeling the isoform ratio. The application of this method to the analysis of CD44 splicing in colorectal cancer cells revealed 20 significant RNA-binding proteins. Many of them were previously shown as EMT regulators, but for the first time presented as potential CD44 splicing factors.
SUBPOPULATION HETEROGENEITY OF NK CELLS DURING THE GENETIC MODIFICATION FOR SUBSEQUENT USE IN TARGETED THERAPY
Authors: Streltsova M. A. , Boyko A. A. , Ustiuzhanina M. O. , Palamarchuk A. I. , Alekseeva N. A. , Velichinskii R. A. , Vavilova J. D. , Grechikhina M. V. , Sapozhnikov A. M. , Deev S. M. , Kovalenko E. I.
Published: April 2024

Obtaining genetically engineered NK cells is one of the developing areas of immunotherapy. In this work, we analyzed the subset heterogeneity of NK cells subjected to retroviral transduction, taking into account the content of adaptive NK cell precursors. It has been shown that subpopulations of KIR2DL2/DL3+, as well as CD57–KIR2DL2/DL3+NKG2C+, can be modified with greater efficiency than the corresponding subpopulations that do not carry the KIR2DL2/DL3 and NKG2C markers. After genetic modification, the CD57–KIR2DL2/DL3+NKG2C+ cells began to express CD57 de novo, acquiring the adaptive NK cell phenotype.
PHARMACOGENETIC ANALYSIS OF THE INTERACTION OF THE LOW-MOLECULAR WEIGHT BDNF MIMETIC DIPEPTIDE GSB-106 WITH TRK RECEPTORS
Authors: Antipova T. A. , Logvinov I. O. , Deyev I. E. , Povarnina P. Yu. , Vakhitova Yu. V. , Gudasheva T. A. , Seredenin S. B.
Published: April 2024

Using TrkA or TrkB receptor gene knockout HT-22 cells showed the selectivity of the interaction of the low molecular weight dipeptide BDNF mimetic GSB-106 (hexamethylenediamide bis(N-monosuccinyl-L-seryl-L-lysine)) with TrkB receptors.
MONOCYCLICITY IN THE FUNCTIONING OF THE ERYTHROID GERM OF HEMATOPOIESIS IN TELEOSTEAN FISH, FOR EXAMPLE OF Platichthys flesus (LINNAEUS, 1758)
Authors: Soldatov A. A.
Published: April 2024

The erythron state was studied in the flounder-gloss (Platichthys flesus, Linnaeus, 1758) during the annual cycle. The number of erythrocytes in the blood and the content of immature erythroid forms were determined: basophilic and polychromatophilic normoblasts in the head kidney (pronephros) and bloodstream. The proliferative activity of cells was judged by the inclusion of 3H-thymidine in immature erythrocytes of circulating blood. It has been showed that the processes of erythropoiesis in the hematopoietic tissue of the flounder-gloss proceed irregularly. The active production of erythroid mass is mainly confined to the post-spawning period. This is evidenced by an increase in the content of immature erythroid forms in the tissue of the pronephros and circulating blood, as well as an increase in their proliferative activity. It is assumed that this is due to the peculiarities of the organization of the red blood system in teleostean fish, which excludes the regular production of erythropoietin in the kidneys.
GENETIC CHARACTERISTICS OF THE BAIKAL SEAL POPULATION (PUSA SIBIRICA)
Authors: Meschersky S. I. , Meschersky I. G. , Solovyeva M. A. , Rozhnov V. V.
Published: April 2024

For the first time, the diversity of nucleotide sequences of different mtDNA loci (the cytochrome b gene and the control region) of the Baikal seal (Pusa sibirica) based on of several spatio-temporal samples was studied. It is shown that in the evolutionary time scale the population formed recently and is in the stage of demographic expansion.