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Herein we report a transition-metal- and acid-free protocol for the reductive amination of carbonyl compounds with DMF using a substoichiometric amount of NaH2PO2·H2O. The general trends and limitations of the method were explored.

Subject. This article discusses the issues of development of telecommunication technologies in Russia in the context of sanctions. Objectives. The article aims to identify and assess the threats to the security of the telecommunications industry of the Russian economy associated with foreign economic restrictions, and propose possible measures to neutralize them. Methods. For the study, we used the systems approach. Results. The article systematizes the challenges to the largest Russian telecommunications companies and presents certain proposals of economic, financial and legal character to prevent possible damage to the industry. Conclusions. The Russian telecommunications infrastructure is a fundamental element that ensures the functioning and interaction of all sectors of the economy. It is necessary to take timely and sufficient measures of State support for the telecommunications industry.

An efficient protocol has been developed for the synthesis of larger condensed arenes from aromatic hydrocarbons and internal alkynes. This protocol uses readily available [CpRhI2]n as a catalyst and Cu(OAc)2 as an oxidant and proceeds smoothly through undirected double C–H activation. The addition of trifluoroacetic acid has a crucial positive impact on the reaction selectivity and the yields of the target products. In contrast to the previously reported catalytic systems, the new conditions allow the use of both dialkyl- and diarylacetylenes with the same high efficiency.

This work demonstrates the influence of the catalyst and alkyne nature on the regioselectivity of rhodium-catalyzed annulation of alkoxy-substituted benzoic acids (such as 3-methoxybenzoic, 3,4-dimethoxybenzoic, and piperonylic acids) with alkynes. Here, X-ray diffraction and DFT calculation data gave evidence that the observed regioselectivity is provided by both steric and coordination effects of methoxy groups. The latter is the result of weak non-covalent C–H⋯O interactions with the supporting ligand rather than with the rhodium atom. We believe that these results are also valid for other reactions of the C-H activation of methoxy-substituted arene compounds.

Using wide-band (0.5-6.5 eV) spectroscopic ellipsometry we study ultrathin [Bi(0.6-2.5 nm)-FeNi(0.8,1.2 nm)]N multilayer films grown by rf sputtering deposition, where the FeNi layer has a nanoisland structure and its morphology and magnetic properties change with decreasing the nominal layer thickness. From the multilayer model simulations of the ellipsometric angles, Psi(omega) and Delta(omega), the complex (pseudo)dielectric function spectra of the Bi layer were extracted. The obtained results demonstrate that the Bi layer can possess the surface metallic conductivity, which is strongly affected by the morphology and magnetic properties of the nanoisland FeNi layer in the GMR-type Bi-FeNi multilayer structures., 6 pages, 4 figures

This article is devoted to solving the inverse problems of exploration seismology of fractures and their uniformly oriented systems using convolutional neural networks. The use of convolutional neural networks is optimal due to the multidimensionality of the studied data object. A training sample was formed using mathematical modeling. In the numerical solution of direct problems, a grid-characteristic method with interpolation on unstructured triangular meshes was used to form a training sample. The grid-characteristic method most accurately describes the dynamic processes in exploration seismology problems, since it takes into consideration the nature of wave phenomena. The approach used makes it possible to construct correct computational algorithms at the boundaries and contact boundaries of the integrational domain. Fractures were set discretely in the integration domain in the form of boundaries and contact boundaries. The article presents the results of solving inverse problems for single fracture length, placement and orientation detection and for system of fractures with variations in the angle of inclination of fractures, height of fractures, density of fractures in the system.

On the basis of the 1,2,3,4-tetrahydrofluorenyl ligand, a simple approach was developed to new effective rhodium catalysts for the construction of C-C and C-N bonds. The halide compounds [(η5 -tetrahydrofluorenyl)RhX2 ]2 (2 a: X=Br; 2 b: X=I) were synthesized by treatment of the bis(ethylene) derivative (η5 -tetrahydrofluorenyl)Rh(C2 H4 )2 (1 a) with halogens. An analogous reaction of the cyclooctadiene complex (η5 -tetrahydrofluorenyl)Rh(cod) (1 b) with I2 is complicated by the side formation of [(cod)RhI]2 . The reaction of 2 b with 2,2'-bipyridyl leads to cation [(η5 -tetrahydrofluorenyl)Rh(2,2'-bipyridyl)I]+ (3). The halide abstraction from 2 a,b with thallium or silver salts allowed us to prepare sandwich compounds with incoming cyclopentadienyl, dicarbollide and mesityleneligands [(η5 -tetrahydrofluorenyl)RhCp]+ (4), (η5 -tetrahydrofluorenyl)Rh(η-7,8-C2 B9 H11 ) (5), and [(η5 -tetrahydrofluorenyl)Rh(η-mesitylene)]2+ (6). The structures of 1 b, 2 b ⋅ 2I2 , 3PF6 , 4TlI4 , 5, and [(cod)RhI]2 were determined by X-ray diffraction. Compounds 2 a,b efficiently catalyze the oxidative coupling of benzoic acids with alkynes to selectively give isocoumarins or naphthalenes, depending on the reaction temperature. Moreover, they showed moderate catalytic activity in other annulations of alkynes with aromatic compounds (such as benzamide, acetanilide, etc.) which proceed through CH activation. Compound 2 b also effectively catalyzes the reductive amination of aldehydes and ketones in the presence of carbon monoxide and water via water-gas shift reaction, giving amines in high yields (67-99 %).

The article is devoted to the study of the propagation of elastic waves in a fractured seismic medium by methods of mathematical modeling. The results obtained during it are compared with the results of physical modeling on similar models. For mathematical modeling, the grid-characteristic method with hybrid schemes of 1-3 orders with approximation on structural rectangular grids is used. The ability to specify inhomogeneities (fractures) of various complex shapes and spatial orientations has been implemented. The description of the developed mathematical models of fractures, which can be used for the numerical solution of exploration seismology problems, is given. The developed models are based on the concept of an infinitely thin fracture, the size of the opening of which does not affect the wave processes in the fracture area. In this model, fractures are represented by boundaries and contact boundaries with different conditions on their surfaces. This approach significantly reduces the need for computational resources by eliminating the need to define a mesh inside the fracture. On the other hand, it allows you to specify in detail the shape of fractures in the integration domain, therefore, using the considered approach, one can observe qualitatively new effects, such as the formation of diffracted waves and a multiphase wavefront due to multiple reflections between the surfaces, which are inaccessible for observation when using effective fracture models actively used in computational seismic. The obtained results of mathematical modeling were verified by physical modeling methods, and a good agreement was obtained.

The article is devoted to the numerical solution of the Stefan problem for thermal effects on an artificial ice island. For modern tasks of the development of the Arctic, associated with the exploration and production of minerals, it is important to create artificial ice islands in the Arctic shelf, due to the speed of their construction, economic feasibility and other factors. The most important task for the exploitation of such islands is their stability, including against melting. This paper discusses the issue of the stability of ice islands to melting. For this, the Stefan problem on the change in the phase state of matter is formulated. An enthalpy solution method is constructed, and the applicability of this method is considered. For the numerical solution, the Peasman-Reckford scheme is used, which is unconditionally spectrally stable in the two-dimensional case, which allows to freely choose the time step. In addition, the developed approach takes into account the flow of water and the flow of melted water, which is important in the task at hand. The developed computational algorithms are parallelized for use on modern multiprocessor computing systems An approach is implemented for modeling thermal processes in the thickness of an arbitrary mass of substances, taking into account arbitrary initial conditions, environmental conditions, tidal currents of water, and solar radiation. This approach was used to calculate the temperature distribution in the thickness of the ice island, as well as to study the impact of seasonal temperature changes on the stability of the island.

Context. An application of the method of a “jumping frogs” search algorithm to construct optimal experiment plans for cost (time) in the study of technological processes and systems that allow the implementation of an active experiment on them is proposed. The object of study are optimization methods for cost (time) costs of experimental designs, based on the application of a “jumping frogs” search algorithm. Objective. To obtain optimization results by optimizing the search of a “jumping frogs” search algorithm for the cost (time) costs of plans for a full factorial experiment. Method. A method is proposed for constructing a cost-effective (time) implementation of an experiment planning matrix using algorithms for searching for “jumping frogs”. At the beginning, the number of factors and the cost of transitions for each factor level are entered. Then, taking into account the entered data, the initial experiment planning matrix is formed. Then, taking into account the entered data, the initial matrix of experiment planning is formed. The “jumping frogs” method determines the “successful frog” by the lowest cost of transitions between levels for each of the factors. After that, the permutations of the “frogs” are performed. The “frog” strives for the most “successful” and, provided it stays close, remains in the location. Then the gain is calculated in comparison with the initial cost (time) of the experiment. Results. Software has been developed that implements the proposed method, which was used to conduct computational experiments to study the properties of these methods in the study of technological processes and systems that allow the implementation of an active experiment on them. The experimental designs that are optimal in terms of cost (time) are obtained, and the winnings in the optimization results are compared with the initial cost of the experiment. A comparative analysis of optimization methods for the cost (time) costs of plans for a full factorial experiment is carried out. Conclusions. The conducted experiments confirmed the operability of the proposed method and the software that implements it, and also allows us to recommend it for practical use in constructing optimal experiment planning matrices.

Heterocyclization of ethyl 2-acetyl(aroyl)-5-methylthieno[2,3-b]thiophene-3-acetates with hydrazine hydrate has been studied. A dependence of the reaction direaction on the nature of the substituent in the acyl fragment was established. The heterocyclization of ethyl 2-aroyl-5-methylthieno[2,3-b]thiophene-3-acetates leads to derivatives of thieno[3',2':4,5]thieno[2,3-d][1,2]diazepin-5-ones. The cyclization of ethyl 2-acetyl-5-methylthieno[2,3-b]thiophene-3-acetate with hydrazine hydrate forms a six-membered ring, viz. 2-aminothieno[3',2':4,5]thieno[2,3-c]pyridin-5(6H)-one.

The elastic effects on an artificial ice island produced by drill impacts and the pressure of structures located on the island are numerically modeled. The problem is solved numerically by applying the grid-characteristic method with interpolation on structured and unstructured meshes. The grid-characteristic method most accurately describes dynamic processes in exploration seismology problems, since it takes into account the nature of wave phenomena. The approach used makes it possible to construct correct computational algorithms at the boundaries and interfaces of the integration domain. Elastic wave propagation in the considered geological environment is studied, the stress distribution is simulated, and the stability of the ice island to fracture is analyzed using the von Mises criterion.

A new synthetic approach to fused azepines was demonstrated on an example of the synthesis of 2-methyl-2,3,4,5-tetrahydro-1H-[1]benzothieno[2,3-c]azepine. The key stage of the synthesis is the formation of the azepine ring under the Eschweiler–Clark reaction conditions. The Gibbs energy of activation for the inversion of the azepine ring was determined by dynamic 1H NMR spectroscopy. Molecular modeling of the structure and estimation of the 1H and 13C NMR chemical shifts were performed for 2-methyl-2,3,4,5-tetrahydro-1H-[1]-benzothieno[2,3-c]azepine. The magnetic shielding tensors were calculated by the standard GIAO method using the B3LYP/6-31G(d,p)-optimized molecular geometry parameters. The solvent effect was taken into account in the PCM approximation. The calculated 1H and 13C NMR chemical shifts of 2-methyl-2,3,4,5-tetrahydro-1H-[1]-benzothieno[2,3-c]azepine are in good agreement with the experimental values observed in the spectra of its DMSO-d6 solution.

Infrared reflection spectra of thin (∼60 nm) Pb1−x Sn x Te (x = 0.25, 0.53, 0.59) films grown by molecular beam epitaxy on GaAs/CdTe hybrid substrates have been measured at frequencies from 20 to 5500 cm−1 and temperatures from 5 to 300 K. The spectra have been used to determine temperature-dependent transverse phonon and plasmon frequencies in the films, which has made it possible to identify a structural phase transition at T C ≈ 50 K. The plasma frequency of the films has been shown to increase with decreasing band gap on cooling from 300 to 77 K. The increase in plasma frequency is mainly attributable to the increase in carrier concentration and a transition of the carriers from vortex states on the film surface to the valence band.

Целью научной работы является изучение физических способностей и физической подготовленности сотрудников органов внутренних дел, необходимых для качественного выполнения поставленных задач, а также возможные пути улучшения физической подготовки сотрудников. Методы проведенных исследований: анализ, обобщение, синтез, дедукции, классификация. Основные результаты научного исследования (научные, практические): заключаются в комплексном исследовании вопросов, связанных с улучшение физических способностей сотрудников органов внутренних дел.

Inverse problems of fracture exploration seismology are solved using machine learning methods. A single fracture of fixed size and subvertical orientation is considered in the two-dimensional case. The spatial position and the inclination angle of the fracture are determined using a neural network. The training set consists of solutions of direct problems produced by the grid-characteristic method on regular rectangular meshes in the form of synthetic seismograms obtained by measuring the vertical velocity on the surface of the medium.

Reflectance spectra of thin Pb1 –xSnxTe films (~60 nm) with x = 0.25, 0.53, and 0.59, grown by MBE on hybrid GaAs/CdTe substrates, are measured in the frequency range of 20–5500 cm–1 and the temperature range of 5–300 K. The temperature dependence of transverse optical phonon frequencies and structural phase transition temperatures are determined based on a dispersion analysis. An increase in the plasma frequency with decreasing temperature in the range 300‒77 K in all films is detected.

The papers dedicated to the procedures of solving direct problems in seismic exploration of fractured formations are considered in this review article. The fractured formations are known to be potential hydrocarbon reservoirs, which are being studied actively at the present time. Due to high cost of field prospecting works, the numerical simulation is an important part in such research, leading to a significant decrease in financial and time expenditures. The papers focusing on conventional popular practical modeling methods based on the use of effective models are considered. A significant part of this work also deals with the papers that use the procedures developed by the authors to solve the formulated range of problems. These procedures are based on a grid-characteristic numerical method with interpolation on unstructured triangular (in the 2D-case) and tetrahedral (in the 3D-case) meshes. The grid-characteristic method most accurately describes the dynamical processes in exploration seismology problems, because it considers the nature of wave phenomena. The used approach allows making the correct computational algorithms at the boundaries and contact boundaries of the integration domain. An important part of this article describes the different models of fracturing. The results of mathematical modeling by the developed procedure, which are presented in the authors’ papers, are also considered. The important practical conclusions made in the considered papers are presented.

The η6-fluorene cyclopentadienyl complexes [(η5-C5R5)M(η6-fluorene)](SbF6)2 (1: M = Co, R = Me; 2a: M = Rh, R = H; 2b: M = Ir, R = H) were synthesized by the iodide abstraction from [(η5-C5R5)MI2]n...

We have tested the conduction band electrons of lanthanum hexaboride that is among the most effective electron-beam sources with one of the highest brightness of thermionic emission. We performed infrared spectroscopic, DC (direct current) resistivity and Hall-effect studies of LaB6 single crystals with various 10B and 11B isotope contents. We find that only a small amount of conduction electrons behave as Drude-type charge carriers while about 70% of the electrons are involved in collective oscillations of electron density coupled to vibrations of both the Jahn-Teller unstable rigid boron cage and rattling modes of La-ions loosely bound to the lattice. We suggest that exactly these non-equilibrium conduction electrons determine the extraordinary low work function of thermoemission in LaB6.

Cyclopentadienyl cobalt complexes have been known since 1953. In the recent years, they have attracted attention of chemists due to their application in C–H activation reactions. The review covers the synthesis of cyclopentadienyl cobalt(III) complexes with diverse auxiliary ligands (such as carbonyl, halides, solvents, arenes, amines, phosphines etc.) as well as their catalytic activity. The influence of auxiliary ligands on the catalytic activity is discussed.

The aim of this article is representing of mathematical modeling results in spatial exploration seismology problems, in particular the problem of seismic waves propagation in fractured layers with fractures of different dimensions. The modeling was produced by grid-characteristic method with use of irregular computational meshes (triangle in 2D-case and tetrahedral in 3D-case). The use of such numerical method takes into consideration the characteristic physical properties of describing processes and give us possibility to construct correct algorithms on boundaries and contact boundaries in integrational domain. By the use of unstructured meshes we can produce computations of wave processes in any areas of different complex shapes.

A number of new 1-substituted 5,10-dihydro[1,2]diazepino[4,5-b]indole-4(3H)-ones were synthesized, and their structural modification was performed to obtain previously unknown amino and fused triazolo derivatives.

Thin epitaxial Pb1−xCdxSe films with cadmium content x ≤ 0.36 have been grown by molecular beam epitaxy (MBE) on highly resistive, lattice matched (0 0 1) ZnTe/GaAs hybrid substrates. The High Resolution X-ray Diffraction (HRXRD) indicates that the films crystallize in the rock salt structure. Up to x = 0.12 the Pb1−xCdxSe films are (0 0 1) oriented and monocrystalline with negligible amount of other phases. The lattice constant of the films decreases proportionally to the Cd content. As evidenced by low-temperature photoluminescence (PL) the energy gap of Pb1−xCdxSe films increases with the increasing Cd content. The parameters of optical phonons and plasmons in the material are established by infrared reflectance measurements. The most interesting property of the Pb1−xCdxSe films is revealed by classical transport measurements. The alloying of PbSe with CdSe reduces the hole concentration in the material from a typical value of 3 × 1018 cm−3 in the pure PbSe film down to 3 × 1016 cm−3 in the film containing x = 0.052 of Cd. The reduction of the hole concentration by two orders of magnitude makes the Pb1−xCdxSe films very attractive for infrared detector applications. Simple photoresistors made of Pb1−xCdxSe films exhibit sensitivity to the infrared radiation up to the room temperature.