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The present work details a new approach to the study of GTU rotor vibrations, based on the solution of a related dynamic problem for the «gas – dynamic flow – deformable structure» sys-tem. The modern tendency to increase an aggregates power with a simultaneous decrease stiffness results in new phenomenons that affected a rotor vibration state. The compressor rotor model with a labyrinth seal is considered. ANSYS software product is used. The calculations were carried out on a high-performance computer complex PNRPU. The performed calculations showed a qualitative and quantitative effect of a gas-dynamic gap on the rotor dynamics. A 2FSI calculations series was performed to study the influence of geometric, kinematic and gas-dynamic parameters on the rotor dynamic state. A pressure fluctuations spectral analysis in the gas-dynamic gap and displacements has been carried out. The obtained spectrograms pro-cessing it possible to plot amplitudes and frequencies dependences of resonant pressure oscil-lations over an initial pressure in the gas-dynamic gap. It was found that the initial pressure in a gas-dynamic gap has the greatest influence. A rotor and gas oscillations resonant frequency was found, which corresponds to a change in the shaft axis spatial position. The «gas – struc-ture» system resonant frequencies were obtained for models differing in mass and stiffness. A decrease in an elasticity modulus of the structure led to a decrease in the maximum pressure fluctuations amplitude, while a decrease in mass led to its increase. For the base model and the model with lower rigidity, the resonant pressure oscillations frequency depends on the initial pressure value according to a law close to linear, while for the model with a lower mass, the dependence has a pronounced non-linear character.

The study of ascorbic acid transformation processes in aqueous - ethanolic systems is an important area of research in food chemistry, and therefore recently there has been an increased interest in studying the possibility of stabilizing ascorbic acid in the form of O -derivatives by the biologically active substances. The paper examines the behavior of ascorbic acid - D -glucose double systems in aqueous-ethanolic media of various compositions (96 % EtOH, 40 % EtOH) under thermal degradation conditions compared to systems without carbohydrate additives. It has been shown that in 40 % ethanol, degradation processes develop faster compared to reactions in 96 % ethanol; in dual systems, regardless of solvent composition, ascorbic acid reacts faster than carbohydrate-free systems. Based on electronic and vibrational spectroscopy data, the joint participation of ascorbic acid and monosaccharide in thermodestruction reactions has been established, which is accompanied by the sequential formation of dehydroascorbic acid derivatives. These derivatives are L -gulono-γ-lactones with different degrees of substitution, containing no endiol fragments of ascorbic acid, and as a result do not have antioxidant properties. As a result of the studies, the absence of ascorbic acid stabilization by D -glucose in the form of O -derivatives in the studied double systems is shown, which is probably due to the formation of thermodynamically stable of dehydroascorbic acid derivatives during the reactions, even in low-water systems. Further studies are planned in the direction of choosing the optimal conditions that allow isolating ascorbic acid derivatives (or molecular complexes) with reducing properties, which will make it possible to obtain products with antioxidant functionality.

The performed condensation of p-aminobenzoic acid with D-mannose produced N-mannopyranosylamine with ? configuration at the anomeric centre, which was confirmed by vibrational spectroscopy. The reactivity of the synthesized product in the processes of acid hydrolysis and thermal oxidation in a freely aerated medium was studied. A hydrolytic stability study showed p-(N-β-D-mannopyranosyl)- aminobenzoic acid, which is stable in ethanolic media, to gradually hydrolyse upon heating (50 °C) in acidic aqueous solutions, as confirmed by FTIR spectroscopy and thin-layer chromatography. Upon thermal oxidation, the synthesized product shows sufficient stability when heated up to 30–50 °C. However, a further increase in temperature to 70 °C accelerates destruction, which is manifested in an increase in the band intensity of 1690 cm-1 (vO=C–C=N) in the spectra of the second derivatives of thermostated samples. This process is assumed to involve direct oxidation of N-glycosylamine, most likely in the acyclic form of enaminol. Additionally, the nature of N-glycosylation by-products was studied by electron and oscillatory spectroscopy. These studies indicated the formation of melanoids – coloured products of deep destruction, which might exhibit growth-regulating and other types of biological activity. The main structural fragments of melanoids are assumed to be formed in solutions through the interaction of enaminol forms with α-dicarbonyl derivatives. Our experimental data obtained earlier also indicate the biological activity of melanoids in arylaminocarbonyl reactions, thereby allowing the technology of obtaining functional products of different stages of sugar-amine interactions to be combined within a single synthesis operation. The feasibility of this approach is determined by the availability of reagents, mild synthesis and product separation conditions, as well as by their environmental friendliness.

Introduction. The paper analyzes the application of composite materials as the main determining method of reducing the mass of the airframe and an unmanned aerial vehicle. Advanced nondestructive testing methods provide assessing the technical condition of these materials, as well as determining stress concentrators on the airframe and an unmanned aerial vehicle with high accuracy in order to make a decision on the further operation of this object under control. The objective of the work was to increase the accuracy and efficiency of the assessment of crack resistance of composite materials through the acoustic emission control.Materials and Methods. This paper presents the nomenclature of composite materials used in the construction of various aircraft, including unmanned aerial vehicles. The most possible probable defects of these materials due to the influence of operational factors are presented. The applied methods of nondestructive testing of composite material and selection of the most suitable one according to specific advantages were compared. An experiment was carried out to determine the strength limits of carbon fiber using a hardware and software complex by acoustic emission method. The research results are presented in the form of drawings projected by the hardware and software complex.Results. The application of the acoustic-emission method of composite material control is described.Discussion and Conclusions. The results obtained experimentally can be used in the process of determining the strength limits of various composite materials by the acoustic emission method of nondestructive testing to assess the technical condition in mechanical engineering, shipbuilding, and aircraft construction. The paper is recommended to researchers involved in the design of aircraft and unmanned aerial vehicles.

In this work, potentially bioactive condensation products of adenine with D-mannose and 6-deoxy-L-mannose (L-rhamnose) were synthesized in water and ethanol solutions. According to FTIR spectroscopy and elemental analysis, mono-N6-glycosylated adenines were isolated from water systems in satisfactory yields, while ethanol solutions contained mixtures of N6 and N9-products, as well as complexes of the latter with copper ions. A detailed analysis of the vibrational spectra of N6-glycosyladenines confirmed the structure of carbohydrate fragments in the form of pyranose rings, while some part of the product was obtained in the form of deoxyaminoketosis. N-rhamnosyladenine was formed with a more than double yield because of a higher stability of rhamnose with regard to side reactions. The reflection spectra of model solutions of glycosyladenines, recorded 4 days after preparation, showed no bands characteristic of free adenine in the range of 1250-1110 cm-1, which indicates a sufficient resistance of the synthesized products towards hydrolytic cleavage under experimental conditions. The conducted biotesting of the isolated products on wheat seeds (Triticum aestivum L.) showed an increase in the content of chlorophylls in seedlings for both mannosilade-nines compared to the control. A decrease in the concentration of synthesized products in germination solutions from 0.1 to 0.001% led to an increase in the accumulation of photosynthetic pigments, while this effect was more pronounced for rhamnosyladenine. The latter can be connected with the structural features of car-bohydrate fragments, in particular, the differences in the hydroxylation degree of glucoside fragments. Future research will investigate the mechanisms of transformation and action of N6-substituted adenines.

We investigate linear instability and 2D nonlinear convective flows of a colloidal suspension stratified in the gravity field in the case of a horizontal colloidal suspension layer with account for the particle interaction. The dependences of the oscillatory convection threshold, the neutral oscillation frequency, and the critical wavenumber on the average volume fraction of impurity are obtained. Nonlinear terms in the diffusion and sedimentation fluxes, which reflect the interaction of nanoparticles, reduce the average concentration gradient across the layer, as well as the convection threshold and the neutral oscillation frequency as compared to an ideal colloidal solution. We perform numerical simulation of a finite-amplitude flow in the form of a traveling wave. In contrast to molecular liquids and ideal colloidal solutions, the spatial structure of the concentration field is successfully described by the first harmonic and exhibits weak spatial anharmonism.

The tensile strength of single-crystal sapphire specimens with c, a, d, r, n, s, g, and m crystallographic orientations (c-, a-, d-, r-, n-, s-, g-, and m-axis specimens) has been measured under shock compression in the stress range of 15–20 GPa. It has been found that the spall strength depends on shock direction and maximum compression strength. The spall strength is greatest, ~12–13 GPa, in m- and a-axis sapphire specimens when the maximum shock stress equals 16 GPa.

Gas particle distribution simulated by hard spheres and located in a gravitational field at a constant temperature is under study. A hard sphere model is poorly applicable to real gases, but it can be used to describe the distribution of nanoparticles in a colloidal suspension. Various models of weakly nonideal gas are compared: virial expansion up to a second coefficient, a Wertheim-Thiel equation in a Percus-Yevick approximation, and a Carnahan-Starling approximation. In the case of virial expansion, an exact analytical solution for an equation of particle distribution by height is obtained. For more complex models, solutions are found using numerical methods. It is shown that accounting for a finite particle size leads to significant changes in the particle distribution as compared to the ideal gas distribution even at small volume fractions. The results obtained using virial expansion are in good agreement with the results obtained using more complex models provided that the volume fraction of the impurity does not exceed 0.1.

The сonvective instability and nonlinear flows of a colloidal suspension in horizontal layer are studied in the case when the layer height is comparable with the sedimentation length of nanoparticles. The numerical analysis is carried out within the Boussinesq approximation on the basis of a modified model that takes into account the dependence of a thermal diffusion flux on the local value of impurity concentration. The stability borders and characteristics of critical disturbances are determined depending on the sedimentation length for colloidal mixture. The bifurcation phenomena and nonlinear evolution of spatiotemporal patterns that develop in the colloid suspension are modeled and discussed, paying special attention to the combined effects of gravity sedimentation, thermal diffusion with negative separation ratio and convection. The nonlinear convection patterns demonstrate the traveling wave dynamics. It is found the new traveling wave solution, which is characterized by an anharmonic distribution of the vertical velocity through the layer.

To identify the possible contribution of relaxation processes to the resistance against high-rate deformation, evolution of shock-compression waves in tungsten carbide (WC) ceramics manufactured by spark-plasma sintering at a maximum compressive stress of 27 GPa is measured. Strong elastic precursor decay upon changing the thickness of the samples from 0.15 to 4 mm is revealed. At maximum shock compressive stresses twice exceeding the Hugoniot elastic limit, a decrease in the spall strength value by about 30% from its value in the elastic region is recorded.

To transport natural gas over long distances, it is necessary to build gas compressor stations that compensate for gas energy losses due to friction. The natural gas uninterrupted supply to consumers depends on their work reliability. The contemporary trend towards increase performance and a simultaneous decrease in structural rigidity lead to previously unpredictable compressor rotor oscillations. The article describes the primary causes of compressor rotor vibrations and some methods of dealing with them. Limitations of existing approaches are overcome by applying multiphysicsmodeling of a fluid and structure interaction using the 2FSI approach. Modeling performed for a labyrinth-seal compressor rotor model. ANSYS software product was chosen to solve the problem, which implements the 2FSI method. The modeling was carried out on a high-performance computer complex PNRPU. Trajectories of a point on the shaft rotation axis was analyze for the solid model. The numerical modeling results of the solid structure taking into account a gas dynamics are presented. The 2FSI calculation results are compared with the solid dynamic modeling results. An imbalance influence on the system dynamic is noted. The simulations 2FSI series were performed to study geometric, kinematic and gas-dynamic parameters influence on the rotor dynamic state. The maximum effect is exerted by an initial pressure in the seal gap. The rotor and gas oscillations resonant frequency was found, which corresponds to a change in the shaft axis spatial position in the 2FSI statement.

The aim of the study was to investigate the processes of formation and structural group composition of the products formed during the reaction of D-glucose with p-toluidine in anhydrous ethanol using electronic and vibrational spectroscopy methods. The evolution of the profiles of the electronic spectra of working solutions shows the formation of a chromophore system: clear peaks at 380 and 440 nm are already present at a reaction time of 60 min. The appearance of an additional maximum at 520 nm (90, 120 min) likely corresponds to the formation of chromophores in condensed structures, as confirmed by a decrease in the values of the E 4 /Е 6 indices over time. The dynamics of the transformation of structural elements is also clearly seen in the analysis of IR spectra: as the reactions proceed, the CH aliphatic component of the structure decreases, while the aromatisation and functionalisation of products by chromophore groups increases. For products obtained between 90 and 120 min, a clear band at 1656 cm -1 , attributed to stretching vibrations of multiple bonds in conjugated C=C – C=O systems and azomethine fragments, indicates the of condensation reactions. In the spectra of insoluble solid products fractionated by water, the intensity of the bands at 1656 and 1190 cm -1 is significantly reduced; this is possibly due to the transfer of some of the coloured low molecular weight products to the aqueous phase. A comparison of the IR Fourier transform spectra of the final solid products with the spectra of natural and synthetic humic-like substances indicates their similar structural group composition. The intensity of the bands at 1620, 1508 and 815 cm -1 indicates a significant contribution of the aromatic component to the structure of the products of water-insoluble fractions; the water-soluble fractions mainly include aliphatic oxygen-containing structures resulting from the oxidative destruction of the initial carbohydrate. The synthesised products seem promising as convenient plant growth regulators with controlled release of the active substance.

Convection of a stratified magnetic fluid in a laterally heated vertical channel is investigated experimentally and theoretically. The dynamics of the behavior of convective rolls, their velocity and deformation, are investigated. It is shown that the complex inhomogeneous structure of the flow is attributed to the stratification of nanoparticles in the gravitational field. On the basis of a mathematical model of convection in the Boussinesq approximation, a large series of computational experiments are carried out for various parameters of the problem: the initial distribution of nanopartciles, the Boltzmann number, the Soret parameter, and the sedimentation length. A range of parameters is found in which the numerical and experimental results are qualitatively similar.

The redistribution of impurity nanoparticles in a colloid mixture has been considered for two cases: (i) the mixture settles in a narrow channel first in the horizontal and then in the vertical position and (ii) the mixture is transferred from a vessel to a narrow channel. A flow that brings the system to stable equilibrium with a true vertical density gradient distorts the initially barometric distribution of impurity nanoparticles. It has been shown by numerical simulation that the initial inhomogeneity of the mixture to a great extent continues to persist in both cases.

In this paper we studied the evolution of shock compression waves in hot-pressed ceramics based on boron carbide and silicon carbide at a maximum compressive stress of 32 and 34 GPa, respectively, to determine the possible contribution of relaxation processes to the resistance to high-rate deformation. At a change in sample thickness from 0.5 to 8 mm, an appreciable decay of the elastic precursor was observed in boron carbide while an insignificant anomalous growth of the elastic precursor with a sample thickness was observed in the experiments with silicon carbide samples of various thickness. The measured value of the Hugoniot elastic limit of samples with a thickness of 8 mm was σHEL = 17.2 ± 1.3 GPa for boron carbide and σHEL = 15 ± 0.1 GPa for silicon carbide.

Convective flows and the transport of nanoparticles are numerically investigated in the vertical slot filled with a colloidal suspension and heated from the side. The thermodiffusion and gravitational sedimentation of the nanoparticles are taken into account. Two different regimes of laminar flow are found. The intensity of the first regime is much lower than in molecular liquids (the magnitudes of the convective and diffusion fluxes have the same order). The second regime is more intensive. The transitions between these two regimes are investigated. It is shown that intensive convective flow completely mixes the colloidal suspension to a homogeneous state as a result of the long transient process.

The сonvective stability of a colloidal suspension is studied in the case when the vertical dimension of the cavity is less than or comparable with the sedimentation length of nanoparticles. The analysis is carried out within the Boussinesq approximation on the basis of a modified model that takes into account the dependence of a thermodiffusion flow on the local value of impurity concentration. A new parameter of the problem is the ratio of the sedimentation length to the vertical dimension of the cavity. For a quiescent colloidal suspension, exact and approximate (in the case of small concentrations) solutions are obtained that describe the distributions of nanoparticles. A transformation is obtained that allows one to investigate the convective stability of a colloidal suspension stratified in the gravitational field by the Galerkin method with a set of simple trial functions. Instability boundaries and the characteristics of critical perturbations are determined. It is shown that, in the case of negative thermodiffusion, a decrease in the sedimentation length leads to a decrease in the convection threshold and the frequency of neutral oscillations.

Based on numerical simulation, the influence of sedimentation on the convective flow of colloid liquids filling a horizontal cell heated from the sidewall is studied. The set of nonlinear equations is solved by the finite-difference method using explicit schemes. Three convective patterns differing in spatial structure and behavior in time are distinguished. The transition between the patterns is accompanied by a jump in the dimensionless heat flow. Bifurcation diagrams of the convection patterns (the dependences of the heat flow intensity on the Rayleigh number) are given. It is shown that the weak flow of a colloidal suspension exists at a low temperature gradient, the intensity of which is several orders of magnitude lower than the intensity of the flow of a homogeneous liquid under the same parameters. The concentration in the flow with a weak intensity is redistributed in such a way that the density gradient becomes almost vertical, and the heat flow across the layer is absent at the same time. The transition from a weak to a strong one-vortex flow filling the entire cell proceeds abruptly. It is found the threshold of the transition from a weak to intense flow depends on the Boltzmann number characterizing the degree of gravitational stratification. One more flow, namely, a three-vortex flow with an intermediate intensity is generated upon a decrease in the Rayleigh number. Stream-function and concentration fields are manifested for all the observed types of flows.

Results of studying of melanoidin formation regularities at interaction of D-glucose and D-xylose with p-amino benzoic acid (PABA) in acidic ethanolic media have been presented; features of the chosen threefold systems are, firstly, existence of the low-active amino-compound of benzene series, secondly, presence of catalytic amounts of the biogenic metal. Regularities of melanoidins structure formation from similar systems are almost not studied, at the same time some important biological properties are predicted for them that demands research of reactions' kinetics and development of techniques of their directional synthesis. Studying has been carried out by synthetic methods in total with a sample drawing technique with UV-Vis-spectrophotometry filing and engaging of FTIR-spectroscopy. Based on electronic spectra analysis more intensive melanoidin formation in case of reaction from D-xylose has been shown, this can be bound to steric hindrance and to ability of aldopentoses to give more reactionary capable intermediates in comparison with aldohexoses. The accelerating role of copper (II) ions as the complexing center catalyzing both formation and degradation of the intermediate products at different reaction stages has been confirmed, at the same time the accelerating action is considerably shown since copper ion concentrations about 60 mg/l, but Cu(II) chelation degree by final products is low. The effect of solvent has been noted, in particular the influence of ethanol on nature of amino-carbonyl interactions manifested in strengthening of carbohydrates tendency to re-cyclization, it also probably accelerates melanoidin formation. The data obtained have shown the percent of carbohydrates direct destruction (caramelization) in the presented conditions is insignificant, that allows developing based on the present researches target synthetic techniques for melanoidin products' preparation.

Near-resonant Raman scattering from the electronic excited \({I_2}\left( {0_g^ + \left( {bb} \right)\xrightarrow{{hv}}D0_u^ + \to X0_g^ + } \right)\) state via the intermediate ion-pair D0 u + state to the X one is observed for the first time. The Raman scattering follows a laser pulse. Its intensity I R is inversely proportional to the squared value of detuning from the resonant D, 22, 51 ← 0 g +(bb), 7, 52 transition, (Δν2)2, according to the theory of near-resonant Raman scattering. The ratio of Raman D → X scattering intensity to that of the D0 u +, ν D = 22, J D = 51 → X0 g + luminescence, I R /I D‒X 0.5 cm–1. The Raman and luminescence spectra are found to be identical.

The T -shaped HeI 2 ( E 0 g + ) van der Waals complexes populated in the HeI 2 ( E , v E = 0–2, n E = 0 ← B ,19, n B = 0 ← X ,0, n X ) excitation pathway have been studied. Analysis of the luminescence excitation spectra as well as the I 2 ( E 0 g + → B 0 u + , D 0 u + → X 0 g + , and D ′2 g → A ′2 u ) luminescence spectra themselves has been carried out. It has been shown that the I 2 ( D → X , and D ′ → A ′) luminescence is due to HeI 2 ( E ← B ) transitions with subsequent electronic predissociation. We have determined dissociation energies of the HeI 2 ( E , v E = 0–2) complexes, vibrational populations of the E , D states and branching ratios of vibrational and electronic predissociations. One can suppose that luminescence of the HeI 2 ( E , v E = 0, n E = 0) complexes occurs.

New experimental data on the behavior of the K8 and TF1 glasses under shock-wave loading conditions are obtained. It is found that the propagation of shock waves is close to the self-similar one in the maximum compression stress range 4-12 GPa. Deviations from a general deformation diagram, which are related to viscous dissipation, take place when the final state of compression is approached. The parameter region in which failure waves form in glass is found not to be limited to the elastic compression stress range, as was thought earlier. The failure front velocity increases with the shock compression stress. Outside the region covered by a failure wave, the glasses demonstrate a high tensile dynamic strength (6-7 GPa) in the case of elastic compression, and this strength is still very high after transition through the elastic limit in a compression wave.

A preparative method of synthesis of N6-α-haloacyl sydnone imine derivatives has been developed. These compounds are convenient intermediates for the synthesis of a large variety of N6-α-amino-substituted and N6-α-thio-substituted acyl derivatives of sydnone imines. The obtained sydnone imine derivatives may be of interest in the context of searching for new physiologically active compounds.

The experimentally detected [1] oscillatory regimes of convection in a colloidal suspension of nanoparticles with a large anomalous thermal diffusivity in a closed horizontal cell heated from below have been simulated numerically. The concentration inhomogeneity near the vertical cavity boundaries arising from the interaction of thermal-diffusion separation and convective mixing has been proven to serve as a source of oscillatory regimes (traveling waves). The dependence of the Rayleigh number at the boundary of existence of the traveling-wave regime on the aspect ratio of the closed cavity has been established. The spatial characteristics of the emerging traveling waves have been determined.

The study of the structure and properties of synthetic analogues of humic substances is an important research task. This paper presents the results of studying the structural and group composition of the products of water-soluble fractions synthesized in the D-glucose - m-aminobenzoic acid and D-glucose - p-toluidine reaction systems using electronic and vibrational spectroscopy. The IR-Fourier transform spectroscopic study shows the similarity of the structural-group composition of the selected products with those for humic and humic-like substances of different origin. The study of growth-regulating ability confirms its presence for the products of both systems, while the aromatic fragments of m-aminobenzoic acid impart higher stimulating activity to the substances. Analysis of the structural-group composition of the products obtained in the framework of computer modelling suggests their potentially non-toxic nature, which makes further research in this direction promising.

The convection of a colloidal suspension, which is a binary mixture of a carrier medium with an admixture of nanoparticles having a large positive thermal diffusion parameter, has been studied for the case of the heating of a horizontal cell from below and periodic conditions at the vertical boundaries corresponding to the experimental situation of ring channels. Bifurcation diagrams have been constructed for vibrational and monotonic regimes of the convection of the colloidal mixture. The time dependences of the maximum stream function and the stream function at a fixed point of the cell, as well as the spatial distributions of the concentration field of the colloid admixture, have been obtained. It has been shown that a stable regime of traveling waves exists in a certain region of the parameters of the problem (Boltzmann and Rayleigh numbers characterizing the gravitational stratification and intensity of the thermal effect, respectively).

The results of a theoretical study are presented dealing with convective heat and mass transfer in a colloidal suspension through a Hele-Shaw cell heated from below. The numerical analysis, based on a multi-component model, reveals that for a certain range of parameter values the dynamical regimes of travelling waves as well as oscillatory fingering formation are stable. The bifurcation phenomena and nonlinear evolution of spatiotemporal patterns that develop in the colloid suspension are modeled and discussed, paying special attention to the combined effects of gravity sedimentation, thermal diffusion with positive separation ratio and convection.

Detailed analysis of interactions between all 0g (+), 1u, and 0u (-) weakly bound states of iodine molecule correlating with the I((2)P1/2) + I((2)P1/2) (bb) dissociation limit has been performed. For this purpose, the 0u (-) (bb) state has been described using analysis of rotationally resolved excitation spectra of luminescence from the g0g (-) state populated in a three-step three-color perturbation facilitated excitation scheme via the 0u (-) state. Energies of 41 rovibrational levels, molecular constants, and potential energy curve have been determined. Energy gaps between closest rovibrational levels of the 0u (-) and 0g (+), 1u (bb) states are found to be large, ∼6 cm(-1). However, interaction of all three 0g (+), 1u, and 0u (-) (bb) states has been observed. It has been found that the 0u (-) and 1u electronic states are mixed by heterogeneous interactions, while their mixing with the 0g (+) one is due to hyperfine interactions predominantly. Admixture coefficients and electronic matrix elements of the coupling between the 0g (+) ∼1u, 0g (+)∼0u (-), and 0u (-) ∼1u states have been estimated.

The procedure for the synthesis of 4-formylsydnonimine derivatives based on the reaction of 4-lithiosydnonimines with (methoxymethylidene)dimethylammonium methyl sulfate was proposed.

Chemical oxidation of a series of sydnonimine derivatives followed by NO release was studied. Substances having alkylamine substituents in the position 3 were shown to be considerably more potent NO donors in comparison with those having alkyl or aralkyl substituents in the position 3. It was suggested that the effect is mainly due to lowering of the activation energy of NO release upon stabilization of the cation formed competitevely by the amino group.

Automatic system for electrochemical monitoring of corrosion parameters of protective metal coatings described substantially accelerates analyses, making them much more reliable and reproducible.

The convective stability thresholds and nonlinear evolution of convective rolls are numerically investigated in a plane horizontal layer of a colloidal suspension with positive separation ratio in the case of no-slip, impermeable horizontal boundaries. The characteristics of the steady and oscillatory patterns are analyzed under heating and gravity stratification. The standing and traveling waves are found as stable solutions within certain domains of parameters (on the plane of the Rayleigh and the Boltzmann numbers). Complex bifurcation and spatiotemporal properties are caused by the interaction of gravity sedimentation, Soret-induced gradients, and convective mixing of the fluid.

Weakly bound valence states of 2g symmetry, correlating with the I(2 P 3/2) + I(2 P 3/2) (aa) and I(2 P 3/2) + I(2 P 1/2) (ab) dissociation limits, as well as (ab) state, were studied using vibrationally resolved luminescence spectra corresponding to transitions from δ2u(3 P 2) and g (3 P 1) ion-pair states, in molecular iodine, respectively, populated using a three-step three-color laser excitation scheme. Spectroscopic constants and potential energy curves of the valence states are determined for the first time. Dipole moment functions of δ2u → 2g(aa, ab) and g → (ab) transitions are found to exponentially decrease.

Thresholds of convection excitation and nonlinear convective flow patterns in a horizontal colloidal-mixture layer heated from below are investigated. We take into consideration the fact that, provided the barometric stratification has been reached prior to imposing the temperature gradient, only oscillatory disturbances develop. The influence of separation ratio, sedimentation length, and Prandtl number on the thresholds of oscillatory convection is studied. To examine the complex nonlinear dynamics of the system, numerical simulations with realistic boundary conditions have been carried out using a finite difference method. Long-wave and cellular instability modes as well as transitions between the conductive state and the traveling-wave regime are discussed. It is shown that the traveling-wave regime is stable within a specified range of heating intensity (the Rayleigh number interval). Complex bifurcation and spatiotemporal properties of dissipative structures caused by the interaction of the gravity-induced concentration gradient, nonlinear advection, and mixing of the fluid with nanoparticles are considered.

The introduction of the phenyl substituent at the benzyl C atom of the arene, π-coordinated by the Cr atom, does not cause any significant changes in the geometry of the binuclear complex which contains a direct Pd-Cr bond [average length 2.768(1) A for the two independent molecules]. The Pd-C benzyl , Pd-C ipso and C benzyl -C ipso bond lengths [averages 2. 138(3), 2.547(2) and 1.452(3) A, respectively] and other geometric features indicate that the title compound may be treated as a superposition of two canonical structures, one of which implies π coordination of the Pd atom by the exocylic C benzyl -C ipso bond whereas the second involves only Pd-C benzyl σ bonding

An α-lithium derivative of 3-alkyl-substituted sydnone was first synthesized by direct metallation of 3-methyl-4-phenylsydnone withn-butyllithium. The reactivity of the compound obtained was studied. Reactions of 3-lithiomethyl-4-phenylsydnone with various electrophiles can serve as a convenient method for preparation of functionalized sydnones.

A method for the synthesis of 4-alkylthio- and 4-arylthiosydnones from 4-lithiosydnones and elementary sulfur was proposed.

The action of sodium amide on tricarbonyl-η 6 -[1′,2′,3′,4′-tetrahydro-spiro(1,3-dioxolane-2,1′-naphthalene)]chromium followed by reaction with sodium bromoacetate gives tricarbonyl-η 6 -[1-(1,2,3,4-tetrahydro-4-oxonaphthalene)acetic acid]chromium ( 4 ). Some procedures to transform 4 into 1-( N -benzyl-2-aminoethyl)-1,2-dihydronaphthalene ( 10 )—a synthon to 6,7-benzomorphanes—are described. Cyclization of 10 by action of mercury(II) acetate yields 3-benzyl-1,2,3,4,5,6-hexahydro-1-hydroxy-2,6-methano-3-benzazocine ( 11 ).

An α-lithium derivative of 3-alkyl-substituted sydnone was first synthesized by direct metallation of 3-methyl-4-phenylsydnone withn-butyllithium. The reactivity of the compound obtained was studied. Reactions of 3-lithiomethyl-4-phenylsydnone with various electrophiles can serve as a convenient method for preparation of functionalized sydnones.

Luminescence spectra corresponding to transitions from β1g, G1g, D'2g, and ion-pair states of an iodine molecule to weakly bound valence states 1u, 2u, and , correlating with the I(2P3/2) + I(2P1/2) (ab) and I(2P1/2) + I(2P1/2) (bb) dissociation limits, respectively, have been observed and analyzed. Energies of vibrational levels, spectroscopic constants, and potential energy curves of the valence states have been determined. The state is shown to be bound by 488(2) cm−1 and placed lower than 1u(bb) and (bb), unlike ab initio estimations.

A method for the synthesis of 4-alkylthio- and 4-arylthiosydnones from 4-lithiosydnones and elementary sulfur was proposed.

The action of sodium amide on tricarbonyl-η 6 -[1′,2′,3′,4′-tetrahydro-spiro(1,3-dioxolane-2,1′-naphthalene)]chromium followed by reaction with sodium bromoacetate gives tricarbonyl-η 6 -[1-(1,2,3,4-tetrahydro-4-oxonaphthalene)acetic acid]chromium ( 4 ). Some procedures to transform 4 into 1-( N -benzyl-2-aminoethyl)-1,2-dihydronaphthalene ( 10 )—a synthon to 6,7-benzomorphanes—are described. Cyclization of 10 by action of mercury(II) acetate yields 3-benzyl-1,2,3,4,5,6-hexahydro-1-hydroxy-2,6-methano-3-benzazocine ( 11 ).