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Abstract: In this work, the synthesis of a magnetite/graphene composite and a magnetic fluid based on it is carried out. The physical–chemical and magnetic–thermal properties of the obtained samples are studied. It is established that in the magnetite/graphene composite magnetite nanoparticles are adsorbed on the graphene surface in the form of aggregates. It is found that the specific surface area and pore volume of the magnetite/graphene composite are higher than the values for magnetite. Analysis of the rheological curves of the magnetic fluid characterizes its structure as homogeneous and indicates a uniform distribution of the dispersed phase in the dispersion medium. It is established that the magnetic fluid with the composite is thermally stable up to 210°С. The values of the specific heat capacity of the synthesized sample are slightly higher than the heat capacity of the liquid without graphene additives. It is noted that the addition of an insignificant part of graphene to the magnetic phase of the magnetic fluid leads to a twofold increase in the value of the magnetocaloric effect (MCE) and changes the shape of the temperature dependence of the MCE in the studied temperature range.

Abstract: The main advantages of direct laser deposition (DLD) of large-sized products are discussed by the example of the internal core baffle of a pressurized water reactor (VVER core baffle). The problem of product damage during operation as a part of reactor is considered. Powder materials made of 08Cr18Ni10Ti and 10Cr16Ni25MoTi stainless steels are produced to develop the DLD process. Optimization of the core baffle design is carried out to improve operating reliability. Samples and experimental small fragments of the core baffle for complex research and tests are manufactured by the DLD method. The concept of an experimental DLD unit for large-scale parts is advanced.

ABSTRACTAn experimental study was conducted to research dolphins’ sonar adaptation capabilities for location of objects obscured by marine sediments. It was shown that dolphins are able to alter spectral and temporal characteristics of their location signals. Adaptive change in length, spectral width and amplitude of signals provides optimal tools to fight interference and allows dolphins to effectively identify objects.

AbstractMethods of safe handling of liquid radioactive waste (LRW) containing tritium are presented in this paper. The first method consists of decreasing LRW specific radioactive activity by separating solid insoluble radioactive components having different fractional compositions without using mechanical filters and chemical treatment. The second method is transition of organic LRW into a solid state.

Abstract: Using a fine-disperse emulsion of sunflower oil in water stabilized by sodium dodecyl sulfate it has been shown that ultraflocculation combined with floatation is an effective means of separation of sta- bilized phases of water-oil emulsions whose complete treatment time may constitute < 0.5 min, while the residual concentration of oil in water < 30 mg/dm3; an increase of the medium gradient velocity in the course of flocculation within the range 500–900 s−1 is accompanied by a monotonic decrease of the residual concentration of oil in the water, which makes it possible to effectively separate diluted water-oil emulsions; an increase of the medium velocity gradient in a flocculator to 104 s−1 makes it possible to decrease the time of ultraflocculation treatment to several seconds.

Data on the experimental and theoretical studies of thermal decomposition of C- and N-nitro compounds of aliphatic, alicyclic, aromatic and heteroaromatic compounds, which formed the grounds for the develpment of ab initio appoach to the prediction of the mechanisms of thermolysis of energetic compounds, are described systematically. The relationships between the structures and thermolysis mechanisms of compounds based on differentiation of the structural fragments depending on the functional surrounding of nitro groups are identified. Using the RRN (Recombination Reaction Network) strategy and original CASB (Computer Assisted Structure Building) softwere, full reaction mechanisms for the thermal destruction of nitro compounds at different thermal decomposition levels (including extensive ones) are simulated. The full set of possible mechanisms of thermal decomposition of 38 chemically different nitro compounds is presented

This paper describes a picosecond laser system based on a hybrid CO_2 laser, using optically controlled semiconductor switches with a pulse width from 100 ps to 300 ns, followed by conversion of the radiation in nonlinear crystals by means of second-harmonic generation. Silver selenogallate AgGaSe_2 and zinc germanium diphosphide ZnGeP_2 are used as nonlinear crystals. Two-stage conversion of the radiation of a picosecond CO_2 laser with wavelength 9.4-10.6 μm into laser radiation with wavelengths 4.7-5.3 μm is carried out in the apparatus with an efficiency of 0.3%-0.5%, while 4.7-5.3-μm radiation is converted into 2.4-2.65-μm radiation with an efficiency of 8%. The overall conversion efficiency is 4×10^−4 or 0.04% for an output pulse energy up to 35 μJ.

Abstract: The character of the quantitative changes in the main physical properties of ordinary chernozems under the impact of irrigation has been studied. It is shown that irrigation leads to a weak or moderate degradation of the aggregate state of the soils and a weak degradation of the soil bulk density, total porosity, and air capacity.

Abstract: The tendency and type of quantitative changes in the main characteristics of the water permeability of automorphic (typical and ordinary) chernozems in the central part of the Russian Plain have been studied in the system of virgin soil (long-term fallow), rainfed plowland, and irrigated plowland. It is shown that irrigation exerts the most pronounced adverse effect on the water permeability of chernozems. The revealed causes of unfavorable changes in the water permeability of chernozems in the region are related to their agricultural use.

Abstract: An equation for the standard enthalpy of solvation of a compound in a binary solvent is derived. The enthalpies of solvation in water-methanol mixtures are estimated for 1,3-propane-and 1,6-hexanediols, 1,2,4-butane-and 1,3,5-pentanetriols, 2-methoxy-and 2-propoxyethanols, and diethylene glycol. The enthalpy of solvation of 1,2-dimethoxyethane in the water-methanol mixed solvent is determined experimentally.

Abstract: The ability of the localizing system of the dolphin Tursiops truncatus to discriminate the dynamic characteristics of an object being located (a radially moving target) was studied. Measurements were made of the thresholds of the animals’ sensitivity to the target speed (2.6 cm/sec) and acceleration (0.6 cm/sec2). For location of a target moving at constant speed, dolphins were found to use probe signals consisting of two impulses, while accelerating targets were located using probe signals consisting of three impulses. These characteristics were used to propose new and highly effective technical methods for hydrolocation and radiolocation.

Abstract: Possible decomposition mechanisms of C-nitro-and N-nitro-1,2,4-triazoles were simulated. We showed that in addition to the experimentally detected thermolysis products including N2, N2O, NO, CO2, HCN, HNCO, 1,2,4-triazole, 3(5)-nitroso-1,2,4-triazole, and 1,2,4-triazolone, some other decompositon products (H2O, CO, NO2, cyanamide, cyanuric acid, and melamine) can be formed. Using the density functional approach (B3LYP/6-31G* approximation), we assessed the most favorable thermal decomposition pathways of nitrotriazoles and studied the relationships between the thermolysis pathways of these substances and their molecular and electronic structures. We found a correlation between the energy gap width (energy difference between the frontier molecular orbitals) and the stabilities of the C-nitro-1,2,4-triazole tautomers to thermal decomposition.

A comparative analysis is done of data on turbulent fluxes measured in the edge plasma in the L-2M stellarator and the FT-2 tokamak. This analysis is performed using the estimation-maximization algorithm to determine finite mixtures of normal distributions that give the best fit to the probability distributions (PDFs) of the increments of turbulent fluxes. The resulting PDFs indicate non-Brownian motion of particles, and the weight of rare transport events (heavy tails of PDFs of fluxes) can be calculated. The number of the normal processes in model mixtures, as well as their weights in the PDFs of the increments of the turbulent flux, change during L-H transition in FT-2. Characteristically, the number of normal processes for the H-regime of FT-2 is the same as for the L-2M stellarator, and the parameters of Gaussians are also similar. This fact may be interpreted as an indirect indication that the L-2M stellarator operates in the mode of improved plasma confinement (which is consistent with the neoclassical theory for stellarators).

Abstract: Densities of solutions of oleic, linoleic, and linolenic acids in n-hexane and n-heptane were measured using a vibrating-tube densimeter at 298.15 K in a concentration range of 0–0.012 molar fractions of solute. The measurement error does not exceed ±5·10−6 g cm−3. The limiting partial molar volumes of fatty acids of the studied series in n-hexane and n-heptane and the excess volume properties of binary mixtures were calculated. On going from oleic to linolenic acid, the number of double bonds (>C=C<) in a solute molecule increases, the hydrocarbon chain length in a solvent molecule decreases, and compactness of the structure packing of the resulting solution increases. This is caused, as a whole, by the enhancement of the n-alkane—acid intermolecular interaction.

The heats of dissolution of benzene, chlorobenzene, ortho-dichlorobenzene, nitrobenzene, and aniline in n-hexane and 1-butanol and those of benzene, chlorobenzene, nitrobenzene, and aniline in a mixture of n-hexane and 1-butanol were measured by calorimetry at 25°C. The enthalpies of solvation of the compounds were calculated. The correlation between the enthalpies of solvation of the compounds and their molar refraction was studied. The enthalpies of solvation of the compounds and their functional groups by the mixture of n-hexane and 1-butanol were considered.The heats of dissolution of benzene, chlorobenzene, ortho-dichlorobenzene, nitrobenzene, and aniline in n-hexane and 1-butanol and those of benzene, chlorobenzene, nitrobenzene, and aniline in a mixture of n-hexane and 1-butanol were measured by calorimetry at 25°C. The enthalpies of solvation of the compounds were calculated. The correlation between the enthalpies of solvation of the compounds and their molar refraction was studied. The enthalpies of solvation of the compounds and their functional groups by the mixture of n-hexane and 1-butanol were considered.

Heats of solution of cyclohexane and squalane in mixtures of 1-octanol with acetone or 1,4-dioxane within the entire range of compositions were measured calorimetrically. The enthalpies of solution of cyclohexane, squalane, and hexadecane in the mixtures of acetone or 1,4-dioxane with 1-octanol show linear correlation. Enthalpies of solvation of propane, decane, and eicosane in these mixtures were calculated.Heats of solution of cyclohexane and squalane in mixtures of 1-octanol with acetone or 1,4-dioxane within the entire range of compositions were measured calorimetrically. The enthalpies of solution of cyclohexane, squalane, and hexadecane in the mixtures of acetone or 1,4-dioxane with 1-octanol show linear correlation. Enthalpies of solvation of propane, decane, and eicosane in these mixtures were calculated.

This work describes results of comparative analysis of the temporary structure of echosignals from spherical targets during their attestation by synthesized signals simulating dolphin's signals and of efficiency of the conditioned reflex recognition by the bottle-nosed dolphin of classes of these targets made of the same material. A possible mechanism underlying classification of targets by dolphin is considered to be difference of the temporal microintervals in the structure of the secondary echo of the reflected signal.

Prolonged storage (45–60 days) of N-methyl- or N-cyclopropylaziridine-2-carboxylates leads to their dimerization through the N—C(3) bond cleavage to form 1,3-disubstituted 2-methylimidazolidine-2,4-dicarboxylates in high yields. Prolonged storage of 1-benzyl-aziridine-2-carboxylate (like the reactions of alkyl pyruvates with primary amines) results in cyclocondensation to yield 3-pyrrolin-2-one derivative.

This paper proposes an illuminator for a laser-diode pumping system that includes a plate–focon system and counter-reflectors, as well as a way to cool the active element of a solid-state neodymium-doped yttrium aluminum garnet laser by means of thermoelectric modules based on the Peltier effect. Results are given of a study of the given laser, operating in the pulsed, pulsed-periodic, and continuous modes. In a flat cavity with backstop and half-silvered output mirrors, a radiation power of 2.5 W can be attained in the beam in the continuous regime.

A method for the synthesis of 1-alkyl-1,2,4-triazolium 4-nitroimides was developed based on alkylation of 4-nitramino-1,2,4-triazole Na and Ag salts with halo- and dihaloalkanes.

Superfine magnetite particles were obtained by chemical condensation. Their size can be varied by the magnetic field application and a change in the crystallization temperature. The X-ray diffraction and adsorption data suggested an increase in the crystallite size and a decrease in the value of limiting adsorption and specific area of magnetite with an increase in the temperature and magnetic field intensity. The nature of surfactants and solvents has a substantial effect on the adsorption process. The IR spectroscopic and equilibrium adsorption data showed that oleic acid has the highest affinity to the surface among the surfactants studied (stearic, oleic, and linoleic acids and sodium oleate). On going from carbon tetrachloride to hexane, the value of limiting adsorption of oleic acid decreases.

Adaptive abilities of the dolphin auditory system at perception of tonal signals of different frequencies were studied under conditions of spatial uncertainty of their presentation in the noise field. It has been shown that a transition from the threshold to the suprathreshold detection is accompanied by adaptive changes of spatial characteristics of auditory perception: transformation of the one-lobe direction diagrams into the two-lobe ones is observed, as well as their broadening and a shift of the sensitivity maximum from the frontal direction to the side one. The dependence of direction characteristics on frequency of the perceived signal is lost.

The behavior of CCl4in methanol-1-butanol, methanol-1-decanol, and 1-butanol-1-decanol is determined by an interaction like CCl4(base)-solvent (acid).

A general method for the synthesis of 1,2,4-triazolium 4N-nitroimides with functionalized substituents in position 1 of the heterocycle was developed. The method is based on the nitration of the corresponding 1-R-4-amino-1,2,4-triazolium nitrates.

The paper compares experimental and calculated pulse shapes and spectra of signals for bidirectional right transducers with radically different protectors, namely, those from epoxy glue with a filler and ceramic. The new data support the previously made conclusion (from calculated parameters of emitted pulses) that in protectors from composite materials (with low propagation velocities of longitudinal elastic waves) signal spectra can have several pronounced peaks, and their waveforms can exhibit beats (oscillating amplitude modulation).

The heats of hexadecane solution in methanol, 1-butanol, 1-octanol, and in their mixtures with acetone, ethyl acetate, and butyl acetate were measured. The enthalpy characteristics of hexadecane in these systems can be only partially described within approaches offered earlier; a method was suggested for calculating these characteristics on the basis of the number of carbon atoms in molecules of the mixture components.

The enthalpies of solution of benzene in the mixed solvents water-1,4-dioxane, water-acetone, and water-dimethyl sulfoxide were determined in the entire ranges of their compositions at 25°C and compared with thermochemical characteristics of n-alkanes. Correlation dependences were obtained that allow one to describe the enthalpies of solution of benzene in the mixtures under study and to predict the corresponding values for other water-aprotic solvent mixtures.

The enthalpies of mixing of water with glycerol over the entire composition range were determined at 298.15 K. The partial excess enthalpies of the components of mixtures of water with glycerol, ethylene glycol, 1,2- and 1,3-propylene glycol, and formamide were estimated and used for examining solvation and the state of water and the organic components in the solutions. The composition of the solvation shells of the components of the mixtures were shown to depend on the nature and structure of the organic solvent.

Enthalpies of aniline solution in mixed solvents water-1,4-dioxane, water-acetone, and waterdimethyl sulfoxide at 25°C were determined within entire ranges of their compositions. The enthalpies of its solvation and transfer from water into mixed solvents, and also contributions of hydrocarbon radicals and functional groups to these quantities were calculated. Effects of composition and properties of the mixtures on the aniline thermochemical characteristics in solutions were considered.

Enthalpy of solution at 25°C of squalane in butyl alcohols and 1-octanol is determined calorimetrically. The endothermic effect of dissolution increases in the order 1-OctOH < BuOH < i-BuOH < t-BuOH. A linear correlation is found between the enthalpies of solution of squalane and hexadecane, from which the enthalpy of solution of squalane in methanol is determined. The contributions of the cavity formation and solute-solvent interaction to the enthalpy of solution are estimated by multiple regression analysis. The enthalpy of cavity formation is only slightly dependent on the length of the main chain of an alcohol and also on the branching type, varying in the order 1-OctOH ∼ BuOH ∼ i-BuOH < MeOH ∼ s-BuOH < t-BuOH. Interaction of squalane with alcocols increases in the order MeOH < t-BuOH < BuOH < ∼ i-BuOH ∼ s-BuOH < 1-OctOH.

The enthalpies of solution (ΔsH0) of aniline in isomeric butyl alcohols and their aqueous solutions at 25°C were determined. The dissolution of aniline becomes more endothermic with increasing content of alcohol in aqueous solution. The enthalpy coefficients of pair interaction alcohol-aniline in aqueous solution were calculated. This interaction is enhanced in the order tert-butanol-sec-butanol-iso-butanol-n-butanol. The correlations of these characteristics with physicochemical properties of solvents were revealed.

This paper reports on the kinetics of diffusion-controlled processes: oxidation of tert-butyl radicals by molecular oxygen, phenanthrene phosphorescence quenching by molecular oxygen, and fluorescence ignition of the anthracene–oxygen geminal pair in an n-butanol–water frozen solution. An anomalous drop of oxygen diffusivity for water contents higher than 2.5-3 v/o has been found. This effect is associated with the microheterogeneous structure of the solution.

Abstract: Paramagnetic derivatives of tolan, anthracene, and terphenyl of the A−Sp−R• type, where A is an aromatic group, R• is a stable radical center, and Sp is a spacer, were synthesized. The electronic absorption and luminescence spectra of these compounds were examined. The introduction of the paramagnetic dihydroimidazole fragment causes a decrease (10–500-fold) in the quantum yield of luminescence compared to emission of the individual aromatic luminophore. The presence of a radical center (R•) in the (alkane)•+/−•A−Sp−R• radical-ionic pair leads to the disappearance or fast (nanoseconds) damping of the magnetic effect of luminescence arising upon recombination of these pairs.

(3,5-Dichloro-2-pyridyl)hydrazine was synthesized by the interaction of 2,3,5-trichloropyridine with hydrazine hydrate. Reaction of the former with carbonyl compounds gave N-(3,5-dichloro-2-pyridyl)hydrazones, and with acid anhydrides N′-acyl derivatives were formed. Azodyestuffs containing 3,5-dichloropyridyl fragments were obtained from some of the hydrazones synthesized.

Abstract: Monte Carlo computer simulation of infinitely dilute solutions of Cs+ and I− ions and Xe atoms inN,N-dimethylformamide (DMF) was performed. Peculiarities of intermolecular interactions and structural properties of the solutions were investigated. The solvation enthalpies of cations and anions are close, but the energies of the ion-solvent and solventsolvent interactions differ appreciably. The solute particles affect the energy and structural properties of DMF only in spatially localized domains. The second solvation shell of the solute particles was not structurally allocated. Two structurally and energetically differing states of DMF molecules (with normal and anomalous orientation of the dipole moments) exist in solution of Cs+ cations. The anomalous orientation of DMF molecules is due to the solvation steric effect, packing, and kinematic factors.

Abstract: The asymptotic properties of Poisson random sums are investigated. A series of convergence-rate estimates in local limit theorems for those sums are obtained.

Abstract: The near-IR spectroscopy method of control of the octane number (o.n.) of a fuel is studied. An analysis is made of a device developed as an alternative of a measuring system based on a nonselective IR radiation source and of an analyzer based on a laser semiconductor diode. It is shown that the use of the methods of multicomponent regression analysis of spectral data allows measurement of the octane number with an accuracy of S ∼ 0.17 octane number units. The characteristics of the semiconductor laser-based analyzer are investigated and the parameters of radiators are discussed that provide the required sensitivity of the measuring system (up to 10−4 with respect to optical absorption) in controlling the octane number of a fucl.

The performed study of peculiarities of echo-detection of moving underwater targets by the Black Sea bottlenosed dolphins,Tursiops truncatus, suggests that the biosonar can purposefully change the structure of its probe signal, depending on the problem to be solved. It was shown experimentally for the first time that the animal emits the two-pulse probe signal to measure the constant velocity, while the three-pulse one, to measure acceleration. This provides an essential advantage over the single pulse, as it becomes possible to measure simultaneously parameters of the movement and distance.