Physical and chemical aspects of the study of clusters, nanostructures and nanomaterials
Founded at 2009


Editor’s column


Formation of biomimetic apatite on calcium phosphate foam ceramics in standard and carbonate-free model solutions

Abstract: The biomimetic apatite was formed in the carbonate-free Simulated Body Fluid model solutions of standard composition on calcium phosphate foam ceramics, consisting of α/β-tricalcium phosphate and β-calcium pyrophosphate. The apatite phase composition was determined by the composition of Simulated Body Fluid solution used during soaking. The equilibrium shift in the model solution during the interaction of calcium phosphate foam ceramics with ions of the solution leads to the apatite precipitation in the aggregated particles form. The excess content of Hions in carbonatefree Simulated Body Fluid leads to pH sharp fluctuations and the inclusion of hydrated СaClH2POimpurity into apatite spherulites. An increase in the soaking time in Simulated Body Fluid model solutions to 21-28 days leads to coarsening of apatite spherulites to 5-6 µm. The foam ceramics surface morphology after soaking changes insignificantly with a slight decrease in the through porosity by 1-3% and two times increase in static strength due to the healing of microdefects in the foam ceramics structure.

Synthesis of carbon nanomaterials by means of microwave-assisted catalytic pyrolysis of cellulose

Abstract: The growing demand for carbon nanotubes, which are typical representatives of the class of carbon nanomaterials and have unique physical and chemical properties, necessitates the search for available and renewable hydrocarbon resources for their production and development of an energyefficient and a highly productive synthesis method. The prospects of using lignocellulosic biomass and its wastes as a carbon source for the synthesis of carbon nanotubes by means of microwave catalytic pyrolysis are considered. The expediency of research in this direction is emphasized. It is noted that one of the parameters responsible for the process of pyrolytic synthesis of carbon nanotubes is the concentration of microwave radiation absorber, which determines pyrolysis temperature. The effect of changing the concentration of microwave absorber in reaction mixture on the catalytic synthesis of multi-walled carbon nanotubes during microwave pyrolysis of cellulose has been studied. It is shown that a change in the microwave acceptor content from 10 to 30% is accompanied by an increase in the concentration of multi-walled carbon nanotubes of disordered morphology in reaction mixture. A twostage pyrolysis-synthesis process is suggested. The results of transmission electron microscopy and Xray phase analysis of the obtained products are considered.

Synthesis of nanocrystal calcium carbonate from bile in the presence of amino acids

Abstract: In this paper, we studied the effect of amino acids in the composition of bile, the formation of various modifications of calcium carbonate (aragonite, vaterite, calcite). In this work, 22 samples of calcium carbonate in bile were synthesized by varying the concentrations of amino acids (histidine, methionine, arginine and tryptophan). For the amino acids methionine and arginine, their stabilizing effect with respect to metastable aragonite has been proven: with an increase in their concentration in bile, an increase in the mass fraction of aragonite in the composition of the solid phase occurs. Optical microscopy showed the presence of vaterite spherulites in all obtained powders. The results of photon correlation spectroscopy correlate with the data of X-ray phase analysis. It is shown that calcium carbonate microparticles with a radius of less than 10 µm are represented by three fractions. It has been shown that syntheses involving histidine and tryptophan, in which, with increasing amino acid concentrations, an increase in the proportion of the small-sized fraction and a decrease in the proportion of the large-sized ones are observed. Thus, all studied amino acids have the potential to be used as medicines for the treatment and prevention of nanocholelithiasis.

Mathematical modeling of formation of nanocrystalline calcium oxalate under physiological conditions

Abstract: For the first time, a physicochemical model of the formation of poorly soluble compounds in the kidney nephron was developed on the basis of a mathematical description of the ideal displacement reactor. As a result of mathematical modeling, it was found that under normal physiological conditions, the formation of a solid phase is not the dominant process, which explains the absence of crystalline formations in the kidneys in healthy people. An increase in the concentration of precipitate-forming ions, corresponding to certain conditions of the human body, leads to the occurrence of local high supersaturations in certain areas of the nephron, which can lead to the formation of solid phase nuclei, their fixation and further growth. It is shown that the calculations of material balances, flow movements, as well as the concentration profiles of components in the nephron determine the possibility of predicting the behavior of the model system with variations in the parameters and conditions that affect the course of the crystallization process (concentration, fluid flow, hydrodynamic regime, etc.), which will allow developing effective methods for the prevention and treatment of urolithiasis, including the dissolution of already formed aggregates.

Determination of the optimal configuration of the molecular system «manganese silicate nanoparticles-an essential amino acid»

Abstract: In this study, the optimal configuration of the molecular system «manganese silicate nanoparticles – essential amino acid» was determined using quantum chemical simulation. To begin with, quantum chemical simulation of individual molecules of manganese silicate and essential amino acids was carried out, after which molecular systems «manganese silicate nanoparticles – essential amino acids» were modeled, in which an oxygen atom attached to silicon atom in manganese silicate was combined with an ionized amino group of amino acids. As a result, it was found that the molecular systems «manganese silicate nanoparticles – essential amino acids» are energetically advantageous and chemically stable. Based on the data obtained, it can be concluded that the optimal configuration of these molecular systems is the interaction of manganese silicate with lysine through the ionized α-amino group of lysine. This molecular system has the highest values of the difference in total energy (ΔE = 73.268 kcal/mol) and chemical hardness (η = 0.144 eV), which are indicators of energy benefits and chemical stability of molecular system. After mixing manganese acetate, L-lysine and sodium silicate, manganese silicate nanoparticles stabilized with L-lysine were obtained.

Development of a biologically active nanosystem based on riboflavin, a microelement of copper and L-lysine amino acid

Abstract: А biologically active nanosystem based on riboflavin, copper microelement and the amino acid lysine copper lysinatoriboflavinate has been developed. The obtained sample of the biologically active additive was studied by a complex of modern methods of analysis, namely: spectrophotometry, scanning electron microscopy, spectrophotoluminescence spectroscopy. In addition, computer quantum chemical modeling was carried out. It has been established that the most energetically favorable model of a biologically active nanosystem based on riboflavin, a trace element of copper and lysine is a model in which riboflavin is bound to the copper ion through the enol oxygen at C2 and the neighboring nitrogen heteroatom N3, and lysine is bound to the copper ion through the carboxyl and amino groups in α position. As a result of the analysis of micrographs of a biologically active nanosystem based on riboflavin, copper microelement and lysine amino acid, it was found that the particles have an acicular structure, the width of individual crystals is from 100 to 300 nm, and the length reaches several microns. The energy-dispersive X-ray spectra of a biologically active nanosystem based on riboflavin, the microelement copper, and the amino acid lysine coincide with the theoretical concepts of the structure of the elements under consideration. The analysis did not show the presence of impurity compounds, which may allow us to judge the high purity of the developed compound.

Sorption of heavy metals from aqueous solutions with synthetic zeolites

Abstract: The work is devoted to the study of the possibility of using synthetic aluminosilicate zeolites obtained from recycled solutions of alumina production by the hydro-alkaline method as sorbents of heavy metal ions (copper, zinc and iron), as well as fluorine and chlorine ions from slightly acidic aqueous solutions. Natural zeolite and graphite were used as comparison samples under the same conditions. The chemical qualitative and quantitative composition, morphology of the initial reagents and the resulting solutions were studied. It has been established that synthetic zeolite exhibits sorption properties with respect to heavy metal ions that exceed the indicators under the same conditions for comparison objects. Also, positive results were obtained during the sorption of chlorine and fluorine ions. The conducted studies allow us to recommend the obtained samples for further research in order to introduce it not only for the extraction of various ions from aqueous solutions, but also for use in various industries.

Synthesis and investigation of functional characteristics of composite materials based on nanoscale hydroxyapatite and synthetic zeolites

Abstract: The article discusses the possibility of obtaining composite materials based on nanostructured hydroxyapatite synthesized by precipitation from solution and synthetic zeolites by mechanochemical synthesis. The synthesized samples are certified using modern physico-chemical methods of analysis. The influence of the qualitative and quantitative composition of the composite and the temperature treatment modes on the sintering processes and the strength characteristics of the studied samples is showed. It has been experimentally established that the maximum strength characteristics and constant composition are possessed by a sample based on hydroxyapatite, the content of the reinforcing additive in which is 15 wt.%. It was also found that the hydroxyapatitezeolite composite exhibits sorption properties against heavy metal ions and fluorine ions. The studies carried out allow us to recommend the samples obtained for further research in order to introduce it into medical practice, but also as a sorption material for the extraction of ions from aqueous solutions.

Formation of copper clusters in the process of biocorrosion of aluminum alloys by microscopic fungi

Abstract: In this work, biocorrosion of D16T and AMg6 aluminum alloys under the influence of microscopic fungi was studied. It has been shown that micromycetes produce reactive oxygen species – superoxide anion-radical, hydrogen peroxide, which initiate biocorrosion of metals. The composition products of biocorrosion of D16T and AMg6 after exposure of the alloys on the lawn of a consortium of micromycetes was determined by energy-dispersive X-ray spectroscopy. An X-ray phase study of alloy biocorrosion products was carried out. Scanning electron microscopy and X-ray diffraction analysis show the formation of nanosized and submicron copper clusters. A physicochemical mechanism of biocorrosion of aluminum alloys by microscopic fungi is proposed. An assumption is made about the mechanism of operation of the «zerovalent metal – hydrogen peroxide» systems, which can trigger a cascade of reactions leading to the destructive oxidation of metals. The paper attempts to explain the role of microfungal community biofilms as the main factor in the mycological corrosion of metals.

Improving the sensor characteristics of binary and ternary oxide nanosystems

Abstract: Currently, adsorption gas sensors are of great interest for environmental monitoring. The approaches to improving their properties include synthesis of nanostructured materials of various shapes and modification of the metal oxide chemical composition. The aim of this work is to develop ways to improve the sensor properties of zinc oxide nanowires by changing the surface structure during processing in solutions of tin and iron compounds, as well as adding special precursors during their synthesis. The layers consisting of zinc oxide nanowires were produced by hydrothermal method. Ternary Zn-Sn-O and Zn-Fe-O nanosystems were synthesized as a result of processing of zinc oxide nanowires in solutions containing potassium stannate and iron sulfate, respectively. ZnO nanowires were also synthesized in a solution containing sodium bromide in addition to the general precursors. The surface chemical composition was analyzed using X-ray photoelectron spectroscopy. Sensor properties were investigated by detecting acetone, isopropanol and methanol vapors. It was shown that the sensor response of the produced samples exceeds the response of the initial zinc oxide nanowires. The samples of Zn-Sn-O ternary oxide system have the best response. The improvement of the sensor response may be associated with an increase in the content of adsorbed oxygen ions on the surface of the samples, the presence of metal cations with different properties as well as the formation of heterostructures.