Search

Sympathetic and sensory nerve fibers regulate osteosynthesis and osteoresorption processes throughout life. Fundamental research and clinical data confirm the existence of functional interactions between neurons and bone tissue cells and indicate the catabolic and anabolic effect of sympathetic nervous system mediators on bone tissue. There is practically no information about the regulation of osteoremodeling in embryogenesis. Objective: to study the effect of norepinephrine on the growth of bone tissue explants in the embryonic period of development. The studies were performed on the bone tissue explants of 12-day old chicken embryos. Norepinephrine (10-10 M - 10-4 M), propranolol (10-10 M), atenolol (10-4 M), urapidil (10-6 M) were added to the experimental Petri dishes. Norepinephrine (10-6 M) stimulates the growth of the bone tissue explants through α1-adrenoreceptors. The osteotoxic effect of high doses of the drug is realized through β2-adrenoreceptors. Embryonic osteogenesis is regulated by norepinephrine in dose-dependent manner. Physiological effect of the substance depends on the interaction with certain types of adrenoreceptors.

The results of studying the evaporation and thermodynamic properties of the TiO2–Al2O3 system in the temperature range 2250–2710 K by high-temperature mass spectrometry are presented. The composition of the vapor is identified, the partial pressures of the TiO2, TiO, and Al vapor species over the studied samples in the indicated temperature range are determined. The determined activities of the components and the excess Gibbs energy in the melt of the TiO2–Al2O3 system at 2345 K point to insignificant deviations from ideality.

The processes of the TiO2–CeO2–ZrO2 system evaporation were studied by high-temperature mass spectrometry. The values of the activities of TiO2 and CeO2 at 2250 K indicate a positive deviation TiO2 activity from the ideal behavior and result an increase in the activity coefficient of CeO2 compared to the binary system CeO2–ZrO2.

The SrO-AlThe samples in the SrO-AlThe vapor composition, temperature and concentration dependences of the partial vapor pressures over the samples under study as well as the SrO activities in the melts of the SrO-AlSignificant negative deviations from the ideality were observed in the melts of the SrO-Al

Ceria-based solid solutions are important materials for high- and medium-temperature electrochemical applications. However, the stabilities of both binary and ternary ceria-based solid solutions are insufficient at elevated temperatures, which limits their application as solid electrolytes or SOFC cathodes. Data on the high-temperature stability of ceria-based ceramics are unavailable in the literature. In the present study, we report a thermodynamic stability investigation of Y2O3-CeO2 and Y2O3-ZrO2-CeO2 solid solutions. The thermal prehistories of binary and ternary systems were investigated using STA, XRD, and ESCA techniques. The vaporization processes were investigated in the temperature range of 1577–2227°С via the Knudsen effusion mass spectrometry technique. Using data on the component activity in solid-phase thermodynamic properties of Y2O3-CeO2 solid solutions, which is represented as the Gibbs energy, the excess Gibbs energy was calculated as a function of the ceria mol. %. It was shown that the reduction of Ce4+ to Ce3+ in Y2O3-CeO2 and Y2O3-ZrO2-CeO2 solid solutions corresponds to less-negative Gibbs energy compared to ZrO2-CeO2 solid solutions.

Interest in insects as a source of valuable biologically active substances has significantly increased over the past few years. Insects serve as an alternative source of chitin, which forms up to 40% of their exoskeleton. Chitosan, a deacetylated derivative of chitin, attracts the attention of scientists due to its unique properties (sorption, antimicrobial, film-forming, wound healing). Furthermore, some insect species are unique and can be used to obtain chitin- and chitosan-melanin complexes in the later stages of ontogenesis. Due to the synergistic effect, chitosan and melanin can enhance each other's biological activity, providing a wide range of potential applications.

The vaporization of Ti3O5 and V2O3 is studied by high-temperature mass spectrometry. Evaporation is carried out from Knudsen effusion cell made of tungsten. It is found that these oxides pass into vapor congruently with dissociation. Equations are obtained for the dependence of the partial pressures of molecular forms of the vapor on temperature in the form log p = –A/T + B.

The processes of gadolinium ferrite and gadolinium cobaltite vaporization was studied. It was shown that the predominant components of vapor are atomic iron and cobalt, which are characteristic for the vaporization of individual iron and cobalt oxides, respectively. The activities of iron and cobalt oxides in GdFeO3 and GdCoO3 were determined.

The thermodynamic properties of the Sm2O3–Y2O3–HfO2 system at 2500 K were modeled based on the generalized lattice theory of associated solutions using experimental data obtained by high-temperature mass spectrometry. A comparison was made between the results of the calculations of the thermodynamic properties of the Sm2O3–Y2O3–HfO2 system using two independent approaches to modeling based on this theory: from the experimental data on the properties of the ternary system and from the data on its boundary binary systems Sm2O3–Y2O3, Sm2O3–HfO2, and Y2O3–HfO2. It was shown that the chemical potentials of the components that were calculated in the studied ternary system using the above approaches much better fit the experimental data in the former case.

On the territory of the Ryazan region, there are currently five 5 power plants with an installed electric capacity of 3,759 megawatt, including two gas turbine thermal power plants, which partially use an alternative fuel of the first generation (biogas) obtained from recycled organic waste through their processing. Experiments on conversion the gas turbine power plants to alternative fuels are being carried out. (Research purpose) The research purpose is to determine the power balance and reliability indicators of power plants based on renewable energy in the power system of the Ryazan region. (Materials and methods) Authors have investigated two gas turbine thermal power plants in the Ryazan power system in Sasovo and Kasimov. The reliability indicators of the gas turbine station equipment were calculated. (Results and discussion) Due to the commissioning of the second stage of the gas turbine power plant in Sasovo and its transfer to alternative sources, authors predict an increase in the growth of electricity generation. Authors considered the system reliability of the gas turbine station. (Conclusions) Analysis of power and electricity balances of power plants based on renewable energy in the power system of the Ryazan region showed that their share in the total electricity generation does not exceed one percent. It was determined that the probability of failure-free operation of electrical equipment lies in the range from 0.9 to 0.98. It was found that the probability of failure-free operation of the equipment included in the high voltage switchgear (10 kilovolts) lies below the standard and is up to 0.93. It was revealed a high probability of failure-free operation of step-up transformers up to 0.99, switching and protective equipment as part of a low voltage switchgear from 0.93 to 0.98. It was found that the transfer of gas-turbine stations to alternative fuel (biogas) obtained from recycled organic waste, will not cause a decrease in the reliability of power supply, since the estimated probability of failure-free operation of the equipment corresponds to or exceeds the normative value of 0.95, and the recovery time does not exceed 2.82 hours.

Reactions of the gas-phase synthesis of lead antimonates were studied. Standard enthalpies of formation and atomization of gaseous PbSbO2 and PbSb2O4 were determined.

The SmThe thermodynamic properties of the SmIt was shown that, at temperatures below 2500 K, the main vapor species over the ceramics based on the SmThe thermodynamic data calculated by the semi-empirical approaches at 2423 K were shown to be lower than the experimental values. However, the Toop and Wilson methods were found to be useful for evaluation of the excess Gibbs energy values at the Sm

Vaporization processes and thermodynamic properties of samarium oxide over the temperature range 2265–2668 K have been studied by means of high-temperature mass spectrometry. The values of vaporization enthalpy of Sm2O3 and enthalpy of formation of samarium monoxide at 298 K have been determined. Dependencies of partial pressures of SmO and Sm over Sm2O3 as functions of temperature have been obtained over the above-mentioned range.

RATIONALE The Sm2 O3 -Y2 O3 -HfO2 system holds promise for applications in the sphere of high-temperature technologies, particularly the development of ultra-high-temperature ceramics. However, the reliability of refractory materials is dependent on the possible selective vaporization of their components leading to changes in their physicochemical properties. Thus, information about vaporization processes and thermodynamic properties of ceramics based on the Sm2 O3 -Y2 O3 -HfO2 system may be of importance for the production of high-temperature materials as well as for the prediction of the physicochemical properties of ultra-high-temperature ceramics. METHODS The Knudsen effusion mass spectrometric method was used, with an MS-1301 magnetic mass spectrometer equipped with a tungsten twin effusion cell used to examine the samples in the Sm2 O3 -Y2 O3 -HfO2 system. Electron ionization of vapor species effusing from the cell was carried out at an ionization energy of 25 eV. RESULTS It was shown that at a temperature of 2373 K, selective vaporization of Sm2 O3 and Y2 O3 occurred in the samples of the Sm2 O3 -Y2 O3 -HfO2 system, with the main vapor species being SmO, Sm, YO, and O. The partial pressures of these vapor species were obtained by the ion current comparison method. The Sm2 O3 activities in the Sm2 O3 -Y2 O3 -HfO2 system were determined and allowed the evaluation of the excess Gibbs energies at 2373 K. The direction of change of the condensed phase of the samples because of selective vaporization of the components was examined. CONCLUSIONS The Sm2 O3 -Y2 O3 -HfO2 system was characterized by negative deviations from the ideal behavior at 2373 K. The excess Gibbs energies evaluated in the present study were approximated using the Redlich-Kister representation and visualized in the form of curves of constant values in the concentration triangle. The data obtained in the Sm2 O3 -Y2 O3 -HfO2 system were optimized using the Barker-Guggenheim theory of associated solutions.

The ceramics based on the Y2O3-ZrO2 system is promising for development of refractory materials including ultra-high temperature ceramics. In the present study the samples of the Y2O3-ZrO2 system were synthesized by the solid-state method. The vaporization processes and thermodynamic properties of the Y2O3-ZrO2 system were studied by the Knudsen effusion mass spectrometric method. The vapor composition, the YO, ZrO, ZrO2 and O partial pressures over the samples as well as the Y2O3 and ZrO2 activities of the Y2O3-ZrO2 system were determined at the temperature 2660 K. Thermodynamic properties (i.e. excess Gibbs energies) of the Y2O3-ZrO2 system obtained in the present study can be described in terms of the subregular solution model.

Thermodynamic properties of the Gd2O3-Y2O3-HfO2 and La2O3-Y2O3-HfO2 systems were obtained by Knudsen effusion mass spectrometric method at the temperatures 2500 K and 2337 K, respectively. Description of the thermodynamic properties of these systems was obtained using the Barker theory. It was illustrated that negative deviations from the ideality in these systems were related to the formation of the Me-O-Y and Y-O-Hf bonds in the solid solutions. Accuracy of the optimization of the thermodynamic data in the Gd2O3-Y2O3-HfO2 system using the Barker theory was checked in comparison with the traditional Redlich-Kister approximation approach.

The vaporization processes and thermodynamic properties of twenty samples in the Gd2O3-Y2O3-HfO2 system in a wide concentration range were studied by high-temperature Knudsen effusion mass spectrometry. At the temperature 2500 K the main vapor species were GdO, YO, and O. From the measured values of their partial pressures activities of the Gd2O3 and Y2O3 as functions of concentration were determined. The HfO2 activity was calculated by the Gibbs-Duhem integration. The resulting excess Gibbs energy function exhibited negative deviations from ideal behavior. For the optimization of the obtained thermodynamic functions of the ternary Gd2O3-Y2O3-HfO2 system the generalized Barker-Guggenheim theory of associated solutions was applied. In an alternative computing procedure the same model was used, but the optimization was based on the available literature data for the corresponding binary Gd2O3-Y2O3, Gd2O3-HfO2, and Y2O3-HfO2 systems. Thus, the Barker lattice model may be used for estimation of the thermodynamic functions of a ternary system on the basis of the data for the corresponding binary sub-systems.

Experimental data and results of quantum chemical calculations on the structure and thermodynamic properties of inorganic associates in a high-temperature vapor were systematized. A criterion for thermal stability was proposed, and the dependences of the atomization enthalpies of these compounds on the atomization enthalpies of the anion-forming fragment were revealed.

Thermodynamic properties of NaNO3-KNO3 melts have been studied by high-temperature mass spectrometry. The activities of the components of the condensed phase have been determined and the changes in the chemical potentials and Gibbs energies of the binary system have been calculated.

Ceria-zirconia solid solutions are the important materials for the application in catalysis and the energy conversion. However, the existing data on the thermodynamic properties of ceria-zirconia solid solutions which is used to distinguish their stability is controversial. In the present work, equilibrium ceria-zirconia solid solutions with 90, 50, 24 and 9 mol.% CeO2 were manufactured using the original sol-gel reverse co-precipitation method with further prolonged thermal treatment for 5–50 h at 973–1373 K. Comprehensive characterizations of the precursor powders obtained were performed via SEM, STA, XRD, ESCA and PSD-analysis. According to XRD observations combined with Rietvield refinement and ESCA the equilibrium solid solutions without an admixture of Ce3+ in the condensed phase were obtained after the calcination of samples at 1373 K. Knudsen effusion mass spectrometry was used to study the vaporization processes and the thermodynamic properties of solid solutions in the CeO2 ZrO2 system at 2150 K. Similar dependence of the CeO2 activity on the condensed phase composition was obtained for solid solutions with various ceria contents, which ensured the equilibrium evaporation. The schematic evaporation process for xCeO2-(100-x)ZrO2 solid solutions at 2100–2500 K was suggested for the first time. It was found, that high temperature behavior of CeO2 ZrO2 system significantly differs from its behavior at lower temperatures, i.e. 873–1373 K, when Ce (IV) to Ce (III) reduction takes place.

Black soldier fly allows to efficiently convert residual biomasses into a valuable source of biomolecules, such as proteins, lipids and chitin. In this study, a new method for obtaining amorphous chitin from the black soldier fly larvae was developed with a further deacetylation step. Amorphous chitin was obtained by direct extraction using concentrated phosphoric acid. The purity of the resulting chitin was confirmed by physicochemical methods (elemental analysis, IR spectroscopy, measurement of primary amines, amino acid analysis). Crystalline chitin and high molecular weight chitosan were obtained by the standard procedure including demineralisation, deproteinisation and deacetylation steps. This method allows to extract chitosan, suitable for a wide range of applications.

RATIONALE Cesium and molybdenum are fission products of uranium dioxide fuel in nuclear reactors, which interact with each other depending on the oxygen potential of the fuel. This leads to formation of various compounds of the Cs2 O-MoO3 system, which are exposed to high temperatures during operation of a reactor or a severe accident at a nuclear power plant. This is why the study of the vaporization and thermodynamics of compounds in the Cs2 O-MoO3 system is important. METHODS Synthesis of the compounds in the Cs2 O-MoO3 system was carried out by sintering Cs2 MoO4 and MoO3 . Characterization of the samples was accomplished with the use of XRD, TGA/DSC/DTA, IR spectroscopy, and ICP emission spectroscopy. Vaporization of the samples under study was carried out from a platinum effusion cell using an MS-1301 mass spectrometer developed for high-temperature studies of low-volatility substances. RESULTS The temperature dependences of partial pressures of vapor species were determined over pure MoO3 and Cs2 MoO4 in the ranges 870-1000 K and 1030-1198 K, respectively. MoO3 , Mo2 O6 , Mo3 O9 , Mo4 O12 , and Mo5 O15 were shown to be the main vapor species over the Cs2 O-MoO3 system in the temperature range 850-1020 K. The component activities, Gibbs energies of mixing, and excess Gibbs energies were obtained as functions of the component concentration at 900, 950, and 1000 K. CONCLUSIONS The thermodynamic properties of the Cs2 O-MoO3 system found in the study evidenced negative deviations from ideality. The MoO3 and Cs2 MoO4 partial molar enthalpies of mixing, the Cs2 MoO4 partial vaporization enthalpy, and the total enthalpy of mixing in the Cs2 O-MoO3 system at 1000 K were obtained for the first time.

Rationale The compounds in the Cs2 O-B2 O3 system are of particular interest for nuclear applications since cesium borates may be formed during accidents in nuclear reactors, affecting the rate of release of radiotoxic isotopes into the environment. Thus, information on the vaporization and thermodynamic properties of cesium borates is necessary for simulation and modeling of the isotope release processes taking place during the nuclear reactor accidents. Methods Compounds in the Cs2 O-B2 O3 system were synthesized by the co-crystallization method with subsequent sintering. The sample characterization was carried out using XRD, TGA/DSC/DTA, IR spectroscopy, and ICP atomic emission spectroscopy. The vaporization and thermodynamics of the samples under consideration were investigated using an MS-1301 mass spectrometer and a single molybdenum effusion cell. The electron ionization method was employed for ionization of the vapor species with an electron energy of 30 eV. The scale of the ionizing voltage was calibrated according to the traditional technique by measuring the appearance energy of gold in the mass spectrum of the vapor over pure gold. Results The main vapor species over the samples in the Cs2 O-B2 O3 system were CsBO2 and Cs2 B2 O4 in the temperature range 789-1215 K and in the concentration range 0.1-0.5 mole fraction of Cs2 O. The temperature dependences of the CsBO2 and Cs2 B2 O4 partial pressures over cesium borate were obtained in the temperature range 767-990 K. The CsBO2 and B2 O3 activities, the Gibbs energies of mixing, the excess Gibbs energies, the partial mole enthalpies of mixing, and total enthalpies of mixing were determined as functions of temperature and composition of the condensed phase. Conclusions As the Cs2 O and B2 O3 activity values evidenced, negative deviations from the ideal behavior were observed in the Cs2 O-B2 O3 system in the temperature range 800-1000 K. The total enthalpies of mixing and the Gibbs energies of mixing in the Cs2 O-B2 O3 system were compared with the literature data, illustrating their mutual agreement.

Cesium and molybdenum are fission products of uranium dioxide fuel in nuclear reactors, which interact with each other depending on the oxygen potential of the fuel. This leads to formation of various compounds of the CsSynthesis of the compounds in the CsThe temperature dependences of partial pressures of vapor species were determined over pure MoOThe thermodynamic properties of the Cs

Rationale The systems containing zirconia, hafnia, and rare earth oxides are indispensable in various areas of high temperature technologies as a basis of ultra-high refractory ceramics. Exposure of the materials to high temperatures may result in unexpected selective vaporization of components or phase transitions in the condensed phase leading to changes in physicochemical properties. Consequently, reliable application of the ceramics based on systems such as Sm2 O3 -ZrO2 -HfO2 is impossible without data on its vaporization processes and thermodynamic properties, which may be used to predict physicochemical characteristics of the ultra-high refractory ceramics. Methods Ceramics based on the Sm2 O3 -ZrO2 -HfO2 system were obtained by solid-state synthesis and characterized by X-ray fluorescence and X-ray phase analyses. The vaporization and thermodynamics of the system considered were examined by the high temperature mass spectrometric method using a MS-1301 magnetic sector mass spectrometer with a tungsten twin effusion cell. Vapor species effusing from the cell were ionized by electrons with an energy of 25 eV. Results The main vapor species over the Sm2 O3 -ZrO2 -HfO2 system were shown to be SmO, Sm, and O at a temperature of 2373 K, indicating selective vaporization of Sm2 O3 from the samples. The partial pressures of these vapor species and the Sm2 O3 activities were determined in the Sm2 O3 -ZrO2 -HfO2 system and allowed the excess Gibbs energies to be evaluated. These excess Gibbs energy values were compared with the results obtained by the semi-empirical and statistical thermodynamic approaches. Conclusions The data obtained in this study showed negative deviations from the ideal behavior in the Sm2 O3 -ZrO2 -HfO2 system at 2373 K. The results calculated according to the semi-empirical methods and statistical thermodynamic Generalized Lattice Theory of Associated Solutions were in agreement with each other. Thus, this evidenced the desirability of further experimental investigation of the Sm2 O3 -ZrO2 -HfO2 system by the high temperature mass spectrometric method.

Systems containing zirconia, hafnia, and rare earth oxides are indispensable in various areas of high-temperature technologies as a basis of ultra-high refractory ceramics. Exposure of these materials to high temperatures may result in unexpected selective vaporization of components or phase transitions in the condensed phase leading to changes in physicochemical properties. Consequently, reliable application of the ceramics based on systems such as SmCeramics based on the SmThe main vapor species over the SmThe data obtained in this study showed negative deviations from the ideal behavior in the Sm