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For improve the quality of harvests, modern farms in many countries widely use fertilizers of mineral and natural origin. To mitigate the negative impact on the environment, they try to minimize the amount of mineral fertilizers applied to the soil by creating composite systems. In particular, powdered composite materials are known based on highly dispersed silica and microquantities of mineral fertilizers, which are applied to the surface of the seeds by dusting. The aim of this work was to develop a new generation of film stimulating coatings based on mixtures of hydrophobic AM-1-300 and hydrophilic A-300 silicas, mineral fertilizers and bioactive components. Mixtures of hydrophilic and hydrophobic silicas in the ratio 1:1 and 1:2 were used to obtain a pasty composite with the given stimulating properties; colloidal starch solution; medium salts of mineral acids, bioactive components “Humifriend” and fungicide “Fital”. Such composite systems were applied directly to the surface of sowing material, grains of wheat variety “Natalka” before sowing in sand and on filter paper, according to DSTU 4138-2002. During the study, the following parameters were measured: seed germination energy, germination and morphological characteristics of wheat germs, which consisted in measuring the length of the root and stem. It is shown that when editing certain amounts of bioactive components to the composition of stimulating pasty composites, it is possible to program the properties of future films and powders: to increase morphological characteristics, uniformity of germination and fungicidal characteristics of composites. It has been found that the presence of mineral fertilizers in pasty composites of silicas mixtures 1:1 and 1:2 has a positive effect on the uniform germination of wheat seeds in the sand and on the filter paper. Instead, the presence in the pastes of the active ingredients “Fital” and “Humifriend”, regardless of the environment where the seeds germinated, there is a significant slowdown in the growth of wheat germ in both environments. It has been found that an excess of hydrophilic silica in the pasty composite leads to the development on the surface of the grains of mycosis lesions, regardless of the germination environment. Therefore, stimulant pastes based on 1:2 silica mixtures must contain fungicides of mineral or biological origin. [ABSTRACT FROM AUTHOR]

Even partial replacement of graphite in the anode of lithium-ion batteries with silicon can significantly increase their specific energy. But the issue is the insufficient life cycle of such batteries due to the accelerated degradation of the liquid organic electrolyte with traditional lithium hexafluorophosphate, especially at elevated temperatures. The subject of discussions and further research are the processes involving a natural oxide layer on the surface of silicon in the manufacture and electrochemical litiation–delitiation of Si-containing electrodes. Among the most promising areas for solving the issues of practical application of silicon are new additives to the electrolyte and polymeric binders for electrode masses. This paper demonstrates the capability of trimethylsilylisocyanate (with aminosilane and isocyanate functional groups) as an additive to a liquid organic electrolyte (LiPF6 / fluoroethylene carbonate + ethyl methyl carbonate + vinylene carbonate + ethylene sulfite) to scavenge the reactive HF and PF5 species that alleviates the thermal decomposition of fluoroethylene carbonate at elevated temperatures. This makes it possible to increase the electrochemical parameters of half-cells with a hybrid graphite–nanosilicon working electrode when using water-based binders – carboxymethylcellulose and styrene-butadiene rubber. The addition of trimethylsilylisocyanate in the electrolyte significantly improves the reversible capacity of hybrid electrodes and reduces the accumulated irreversible capacity during prolonged cycling at normal temperature and after exposure at 50 °C, therefore to be effective for use in high-energy lithium-ion batteries. Even partial replacement of graphite in the anode of lithium-ion batteries with silicon can significantly increase their specific energy. But the issue is the insufficient life cycle of such batteries due to the accelerated degradation of the liquid organic electrolyte with traditional lithium hexafluorophosphate, especially at elevated temperatures. The subject of discussions and further research are the processes involving a natural oxide layer on the surface of silicon in the manufacture and electrochemical litiation–delitiation of Si-containing electrodes. Among the most promising areas for solving the issues of practical application of silicon are new additives to the electrolyte and polymeric binders for electrode masses. This paper demonstrates the capability of trimethylsilylisocyanate (with aminosilane and isocyanate functional groups) as an additive to a liquid organic electrolyte (LiPF6 / fluoroethylene carbonate + ethyl methyl carbonate + vinylene carbonate + ethylene sulfite) to scavenge the reactive HF and PF5 species that alleviates the thermal decomposition of fluoroethylene carbonate at elevated temperatures. This makes it possible to increase the electrochemical parameters of half-cells with a hybrid graphite–nanosilicon working electrode when using water-based binders – carboxymethylcellulose and styrene-butadiene rubber. The addition of trimethylsilylisocyanate in the electrolyte significantly improves the reversible capacity of hybrid electrodes and reduces the accumulated irreversible capacity during prolonged cycling at normal temperature and after exposure at 50 °C, therefore to be effective for use in high-energy lithium-ion batteries. [ABSTRACT FROM AUTHOR]

In spite of the widespread opinion about the negative effect of chaos on the nature and human life, there exist examples of its constructive role in various processes. Among them, a prominent position is occupied by the processes in which thermal noise causes not only Brownian motion but also drift of nanoparticles as a result of unbiased non-equilibrium perturbations of various nature in systems with broken spatial and/or temporal symmetry. Such processes are relevant to the operation of Brownian motors, or ratchets, actively studied in the past decades. In the present paper, the working principles of systems of this kind are explained based on the author’s approach which unifies the treatment of different ratchet effect manifestations in the models of fluctuating potential, catalytic wheel, and electroconformational coupling. Another manifestation of this effect is provided by the paradoxical games proposed by Parrondo in which chaos appears in random tosses of a die and the ratchet effect arises from a certain alternation of game strategies ensuring an average win. The paper presents the simplest version of Parrondo’s game; it consists in the alternation of two antisymmetric games, with the rules depending on the parity of the capital possessed by the player before the next toss. The dependence of the average win on the number of tosses is calculated by computer simulation and compared with the result of the catalytic wheel model valid in the adiabatic approximation. The theoretical win calculated by this model agrees well with the numerical simulation result for the game concerned. The attractiveness of the treatment of the ratchet effect in terms of game theory stems from the possibility to visualize the theoretical framework and to study the laws of Brownian motor operation by simple modelling methods. [ABSTRACT FROM AUTHOR]

Despite the large number of experimental and theoretical works devoted to the structure and properties of silica surface known in the literature, as well as the extensive research on the structure of hydrated ionic pairs, the mechanism of adsorption of hydrated ions of electrolytes on silica surface has not yet been studied sufficiently. The paper presents a review of experimental works devoted to this problem, as well as their analysis at the atomicmolecular level. In order to study the interface "the silica surface - a solution of electrolyte", a number of papers used a method of density functional theory (DFT) using the exchange-correlation functional В3LYP and the basis set 6-31++G(d,p). The environmental impact modeling was taken into account within the framework of the supermolecular approach using a continuum solvent exposure model (PCM). The structure of the double electric layer and the mechanism of proton exchange in the near-surface layer of the silica surface are considered, as well as the value of the Gibbs energy of the silanol group deprotonation reaction, from which, in turn, the value of pKa2 was obtained. The results of calculations have shown that, with increasing size of oligomer molecules of silicic acid, the degree of localization of charges on hydrogen atoms and oxygen of the silanol group increases, the length of the O-H bond increases and the pKa2 decreases. It is shown that when adsorbed on a silica surface, alkali metal cations, in contact with silanol groups, can change the protolytic equilibrium of surface groups, due to redistribution of electron density, thereby increasing their acidity. The processes of ion exchange on silica surface and the dependence of the pKMe value on the size of ions and pH are considered. In a strongly acidic medium on silica surface, the formation of a cationic form of the silanol group is probable due to the proton transfer from the ion of hydroxonium to the oxygen atom of the silanol group. The deprotonation constant pKa1 of the cationic form of the silanol group depends on the nature of the anion and increases as an absolute value with anion radius increase. The models considered allow us to find the theoretical value of the point of zero charge of silica surface, which corresponds to the experimental data. Calculations using the constructed models of adsorption complexes of alkali hydroxides for the molecular state and for the state with separated charges with the participation of water molecules and silanol groups of silica surface indicate a possibility of ionization of the silanol group. The calculated Gibbs free energy changes are used to determine the values of pKMe, which increase in the series Li

Man-caused load on sources of industrial and domestic water supply, which causes the discharge of insufficiently treated wastewater, is one of the great environmental problems in Ukraine. The traditional way of solving this problem, associated with the disposal of such waters by adsorption, membrane or catalytic technologies, has a number of disadvantages associated with large volumes and a wide range of pollutants, traditional methods often require preparatory measures, time-consuming, scarce materials and expensive equipment. It would be ideal to create wastefree circulating water supply technologies, but these options are still far from being mass-produced. A promising way to solve these problems is to organize such production cycles, where the disposal of toxic wastewater will be combined with recovery technologies. Industrial and domestic wastewater often contains a significant proportion of the organic component. These are oil products, by-products of organic synthesis, spent lubricating and cooling suspensions, waste from the food, alcohol and pulp and paper industries, dyes and pigments, etc. All this waste is energy saturated and can be separated and used as fuel. However, due to low concentrations in most wastewater, their separation is economically unprofitable. A method is proposed for neutralizing toxic organic wastewater by using it as a dispersion medium for composite coal-aqueous fuel (CAF). The possibility of priming carbon microparticles obtained by preliminary plasma-chemical treatment of an organic dispersion medium to stabilize composite coal-water fuel were investigated. Waste cutting fluid (JCL) was used as an organic dispersion medium; anthracite served as the dispersed phase. A CAF sample was obtained based on anthracite from Ukrainian deposits with a solid phase (W) content of 70 mass. %, and studied its electrokinetic and rheological properties. It has been found that the preliminary plasma-chemical conversion of organic wastewater used as a dispersion medium for composite water-coal fuel significantly improves the operational properties of CAF. The growth of sedimentation stability and the optimization of the effective viscosity are achieved mainly through the implementation of the structural and mechanical factor by increasing the number of contacts with the introduction of a highly dispersed fraction of carbon microparticles and increasing the electrostatic repulsion of the elements of the suspension structure. Thus, the sedimentation stability of the obtained CAF is significantly improved in comparison with conventional anthracite suspensions in organic wastewater and reaches 2 days without the addition of stabilizers. In the future, it is planned to further improve the properties of CAF by introducing stabilizing reagents and dispersants into its composition. [ABSTRACT FROM AUTHOR]

A relevant and important question in studying the transport of nanoparticles is the possibility and methods of controlling the generated currents. One of the possibilities is to use the ratchet effect, i.e. the occurrence of directed motion as a result of the influence of nonequilibrium fluctuations of various nature when one or more symmetries in the system are broken. To implement the ratchet effect, a deterministic dichotomous process is often used, which can be modeled by two alternating states that have constant characteristics. Usually, the main factor determining the direction of motion of a Brownian motor is the spatial asymmetry of the potential profile. In certain cases, for example, for a double-well potential profile, one can relatively easily investigate the conditions for reversal of the direction of motor motion. In this paper, using the idea of Parrondo’s paradox games consisting of alternating strategies of a game that provides an average winning, we simulated the ratchet effect for a diffusion hopping model of an adiabatic Brownian motor with an asymmetric double-well on-off potential. The conditions affecting the direction of nanoparticle motion are investigated, the possibility of temperature control of the motion direction is shown, and an estimate of the generated average velocity of the Brownian motor in the adiabatic approximation is obtained. The motor functioning is simulated in terms of the game theory and the average trajectories of capital accumulation are obtained, which correspond to the trajectories of the average displacement of a Brownian particle due to the ratchet effect. For the chosen model, it is shown that, at low temperatures, a particle moves to the right in accordance with the simplest on-off ratchet model, while, at high temperatures, the motion reverses. A comparison of the simulation results with the values of the ratchet velocity obtained within the adiabatic approximation shows that this approximation becomes valid at sufficiently large values of the lifetimes of the states of the dichotomous process, and it turns out to be much more accurate in the high-temperature region than in the low-temperature one. [ABSTRACT FROM AUTHOR]

This paper summarizes the cycle of authors’ studies devoted to polyamic acid-based Langmuir–Blodgett (LBF) functionalized by organic dyes. Previously reported results are supplemented with new experimental data. The monolayers of the polyamic acid under study, poly(4, 4'-diphenyl oxide)-2-carboxyisophthalamide, on water surface, which contains 1 10–5 М Pb2+, at pH 5.8–6.0 the limiting area per repeating unit is Sm = (0.52±0.02) nm2. The character of the compressing isotherms depends on the pH of the subphase because of the presence of the carboxylic group in the polymer unit. The monolayers and corresponding LBF obtained by the Schaefer method on solid support were modified via n-octadecyl alcohol, N-n-octadecylpyridinium bromide, and acid-base indicators and luminophores. For this purpose, n-decyl esters of fluorescein and eosin, rose Bengal B, n-heptadecyl ester of rhodamine B, N,N'-di-n-octadecylrhodamine, bromothymol blue, quinaldine red, and duplex quinaldine red are used. As a rule, the LBF contained 30–60 monolayers and 2 to 23 molar percent of dyes. The character of the emission and absorption spectra of rhodamine and hydroxyxanthene compounds in the mixed LBF as well as in multilayers of N-n-octadecylpyridinium bromide and stearic acid indicates the weakening of the dye dimerization and further aggregation of these dyes by the matrix. The procedure of determination of the apparent ionization constants of the dyes, pKaapp, consisted in immersing of the LBF during 1–5 min into the aqueous solutions with different pH, air drying during several min, and measuring the absorption spectra. Experiments are performed as a rule at ionic strength of the subphase 0.05 М maintained by NaCl additives and 20 °С. Analysis of thus obtained pKaapp (≡ – lgKaapp) values allows concluding that they are in outline close to the corresponding values obtained in micellar solutions of surfactants. These pKaapp values may be divided into three groups. In the LBF consisting of entire N-n-octadecylpyridinium bromide, without polyamic acid, the pKaapp values are generally close to those obtained for the same indicators in micelles of cationic surfactants and in droplets of cationic N-cetylpyridinium chloride-based microemulsions. An expressed differentiating action of this kind of BLF pseudophase is observed. The value of the electrostatic potential in the indicator locus is estimated as + 107 mV. The second group is represented by the pKaapp values of indicators in polyamic acid-based LBF modified either by N-n-octadecylpyridinium bromide or n-octadecyl alcohol in the acidic region of pH. Under these conditions, the COOH groups of the polyamic acid are non-ionized, and the pKaapp values are also close to those in cationic surfactant micelles. Finally, the third group of pKaapp values corresponds to the pH region of 4–10. Here, the ionization of carboxylic groups of polyamic acid takes place. As a result, the transition range of indicators is anomalously expanded. It is these indicator equilibria that can be used in pH-sensor devices. The obtained results are compared with those reported by other authors. In addition, the peculiarity of dissociation of four-charged and triple-charged cations of the duplex quinaldine red is considered and compared with the dissociation of doublecharged quinaldine red. [ABSTRACT FROM AUTHOR]

The paper deals with a relatively new type of three-dimensional sorbents that are called metal-organic frameworks. The chemical compounds of this kind can be regarded as crystal sponges since they are microporous solid phases with exclusively large area of accessible internal surface. The most expressive manifestation of the peculiarity of the metal-organic frameworks is the topological equivalence of the metal-organic frameworks with principally different chemical nature. This phenomenon is sometimes called an isoreticular paradox. Such sorbents possess an exclusive identity of pores which is provided by the crystalline order in their structures. In its turn the crystalline order of the structure imposes severe restrictions on the geometry and topology of cavities in the structure frame and on the spatial symmetry of the structure itself. Revealing the characteristic features of structure forming in metal-organic coordination polymers enabled to estimate the relative frequencies of possible spatial structures of metal-organic frameworks. The isoreticular paradox originates from the finite number of formally possible Fedorov groups being aggravated by the sharply uneven distribution of the probabilities of these groups in real crystal structures. An atomic configuration of a frame cavity is isomorphic to a concave polyhedron. The symmetry of such polyhedra is to comply with the crystal lattice. We have found eleven Hessel groups that correspond to possible cavity polyhedral and estimated the relative probabilities of cavity configurations in the frame structures. The structural design of framework sorbents should provide the topologic combinations of atomic complexes and molecular linkers providing the cavity configurations of the above mentioned eleven types and forming the centrosymmetric spatial structure. [ABSTRACT FROM AUTHOR]

In view of the chemical stability and inactivity of the polymer, polyvinylidene fluoride membranes are widely used in the processes of concentration, separation and fractionation of substances of different chemical nature. Because of the hydrophobic nature of the surface, these membranes are highly exposed to contamination, which significantly reduces their useful life. This paper is devoted to the development of a method of modifying the surface of polyvinylidene fluoride membranes with water-soluble polymers containing amino groups such as polyethyleneimine of branched structure and polyallylamine hydrochloride of linear one. The advantage and novelty of this method consist in the simplicity of modification (only one stage) and the usage of cheap non-aggressive reagents. Polymer grafted to the membrane surface was used as a linker for immobilization of magnetite nanoparticles. Magnetic nanoparticles fixed on polymeric linkers create oscillations in the boundary layer and cause additional turbulization when an external magnetic field is applied. Membranes modification with polyethyleneimine and polyallylamine hydrochloride is confirmed by IR spectroscopy. Immobilization of magnetite nanoparticles onto the membrane surface is confirmed by scanning electron microscopy. Surface properties of modified membranes are studied using electrokinetic analysis. It has been shown that grafting of the branched linker increases zeta potential of the membrane surface in two times comparing with the linear one. The transport properties of magnetically active membranes were studied in the process of ultrafiltration of BSA solutions. The dependence of the volume flux through the membranes on the applied pressure at various concentrations of protein has been studied. It is shown that immobilization of magnetite nanoparticles on the membrane and their movement in the boundary layer under the influence of a magnetic field reduces the effect of concentration polarization. [ABSTRACT FROM AUTHOR]

The problem of environmental purification from petroleum pollution today is becoming increasingly topical. To solve this problem, the bioremediation way based on the processes of petroleum products decomposition by means of microorganisms that are capable to oxidize hydrocarbons is the most perspective method. The model composite system based on the mixture of nanosilica powders and Saccharomyces cerevisiae yeast cells was created by us to destruct the petroleum products. The purpose of our investigation was to improve the composition of the composite by adding the mineral compounds (KCl - 1.5 %, CuSO4 - 0.3 %, ZnSO4 - 0.4 %, (NH2)2CO - 3.0 %, Ca(H2PO4)2 - 0.35 %) that can increase the efficiency of yeast cells in the destruction of motor oil hydrocarbons and to investigate the pH influence of aqueous media on the bioremediation. In this paper, it has been found that the presence of the mixture of hydrophilic (A-300) and hydrophobic (AM1-300) silicas increases vital activity of yeast cells without of nutrient medium. The results show when the additional source of mineral nutrition is added to the nanocomposite, the 1.4 to 1.2 times increase of yeast gas evolution as well as the 1.7 to 3.3 times biomass growth compared to the blank; and 1.3 to 2 times one compared to the mixture of nanosilica powders without additives was observed. The release of carbon dioxide gas by cells suspension at pH 4.0 was 2 times decreased and 1.5-2 times raised at pH 8.0 compared to the blank. Moreover, gas evolution in the alkaline medium was 3.5 times higher than that in the acidic one. It showed be noted that destruction of motor oil hydrocarbons can be visually observed as gradual destruction of the oil layer on the water surface. Consequently, the experimental results obtained during this research are crucial for the development of new effective methods of water and soil purification from the motor oil pollutants. [ABSTRACT FROM AUTHOR]

In this paper heterogeneous subjects are investigated, namely laminated nanoparticles and flat-layered media. Common feature of objects under consideration is presence of surfaces divided into slabs with different physical characteristics. The aim of the work is to demonstrate large possibilities and certain preferences of transfer matrices method for solution different problems of applied physics and generalization of the results taken out by author early. The method is especially convenient for analysis of such systems under action of different external physical fields. The method makes possible to transfer boundary conditions from slab to slab, to avoid the necessity of consideration of high order algebraical systems and matrices inversion problem is reduced to theirs simple multiplication. We presented a general scheme of building transfer matrices based on conversion of partial differential equations to ordinary differential equations with using expansion by a system of orthogonal functions. In addition to known results, the transfer matrices for inhomogeneous differential equations are constructed, i.e. those for physical systems with internal energy sources. Transfer matrix method has been used to solve some applied problems, especially problems of electromagnetic scattering on ellipsoidal nanoparticles (electrostatic approximation), spherical particles (electrostatic and wave approximations), expressions for calculations of electrical energy in slabs are found. Solution of Eigen value problems for multilayer panels is constructed, design formulas for determination of oscillation Eigen frequencies of multilayer panel with using three-dimensional elasticity theory are also obtained. Design formulas and some typical artwork are presented. [ABSTRACT FROM AUTHOR]

In this paper, we present a theoretical analysis of heating spherical bimetallic nanoparticles with a silver core and a golden shell using laser radiation. The aim of the work is to prove a possibility for applying laser hyperthermia in oncology with use of these nanoparticles. At this, a power and distribution of heat sources in a nanoparticle should be found with subsequent estimation of the temperature in its environs. We investigated a spatial distribution of the field energy in a particle within the electrostatic approximation for homogeneous field acting along the sphere axis. In this case electrostatic energy keeps a stable value in the core but corresponding expression for the shell consists of two terms of the series in expansion on Legendre polynomials. We have constructed a solution of the heat transfer equation for a sphere in a capsule with internal heat sources which intensity is formed by energy distribution of the electrical field. The calculations made show that the temperature necessary for destruction of onco-cells in the nearest environment of the particle can be reached using the laser power that is safe enough for a body system. [ABSTRACT FROM AUTHOR]

This paper presents the results of studies targeted at designing novel high output nanocomposite catalysts, including those on the structured supports, for a number of producing and the environmental catalysis processes (reforming of methane and methanol producing hydrogen (synthesis gas), epoxidation of ethylene with nitrogen oxide(I), deep oxidation of methane, three-component (CO/NOx/CnHm) conversion, DeNOx-processes). Effects of modifying by the oxides of alkali and rare-earth metals, the role of promoters as well as an optimum combination of redox and acidic characteristics of the surface of transition metal oxide based catalysts are shown in the regulating and optimizing their functional properties. [ABSTRACT FROM AUTHOR]