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The condensation reactions of β- and γ-amino alcohols containing phenyl or (η6-arene) tricarbonylchromium substituent with formaldehyde, acetaldehyde, benzaldehyde, and (η6-benzaldehyde)tricarbonylchromium were studied. The resulting 1,3-oxazolidine and 1,3-oxazinane products were isolated in a pure form and identified by different physicochemical methods. The effect of (η6-arene)tricarbonylchromium moiety on the reaction process was demonstrated. [ABSTRACT FROM AUTHOR]

MSb2O6 compounds (M = Mg, Co, Ni, Cu, Zn) are known in the tetragonal trirutile forms, slightly distorted monoclinically with M = Cu due to the Jahn–Teller effect. In this study, using a low-temperature exchange reaction between ilmenite-type NaSbO3 and molten MSO4–KCl (or MgCl2–KCl) mixtures, these five compositions were prepared for the first time as trigonal layered rosiaite (PbSb2O6)-type phases. Upon heating, they irreversibly transform to the known phases via amorphous intermediates, in contrast to previously studied isostructural MnSb2O6, where the stable phase is structurally related to the metastable phase. The same method was found to be applicable for preparing stable rosiaite-type CdSb2O6. The formula volumes of the new phases show an excellent correlation with the ionic radii (except for M = Cu, for which a Jahn–Teller distortion is suspected) and are 2–3% larger than those for the known forms although all coordination numbers are the same. The crystal structure of CoSb2O6 was refined via the Rietveld method: P3̅1m, a = 5.1318(3) Å, and c = 4.5520(3) Å. Compounds with M = Co and Ni antiferromagnetically order at 11 and 15 K, respectively, whereas the copper compound does not show long-range magnetic order down to 1.5 K. A comparison between the magnetic behavior of the metastable and stable polymorphs was carried out. FeSb2O6 could not be prepared because of the 2Fe2+ + Sb5+ = 2Fe3+ + Sb3+ redox reaction. This electron transfer produces an additional 5s2 shell for Sb and results in a volume increase. A comparison of the formula volume for the stable mixture FeSbO4 + 0.5Sb2O4 with that extrapolated for FeSb2O6 predicted that the trirutile-type FeSb2O6 can be stabilized at high pressures. [ABSTRACT FROM AUTHOR]

MSb2O6 compounds (M = Mg, Co, Ni, Cu, Zn) are known in the tetragonal trirutile forms, slightly distorted monoclinically with M = Cu due to the Jahn–Teller effect. In this study, using a low-temperature exchange reaction between ilmenite-type NaSbO3 and molten MSO4–KCl (or MgCl2–KCl) mixtures, these five compositions were prepared for the first time as trigonal layered rosiaite (PbSb2O6)-type phases. Upon heating, they irreversibly transform to the known phases via amorphous intermediates, in contrast to previously studied isostructural MnSb2O6, where the stable phase is structurally related to the metastable phase. The same method was found to be applicable for preparing stable rosiaite-type CdSb2O6. The formula volumes of the new phases show an excellent correlation with the ionic radii (except for M = Cu, for which a Jahn–Teller distortion is suspected) and are 2–3% larger than those for the known forms although all coordination numbers are the same. The crystal structure of CoSb2O6 was refined via the Rietveld method: P3̅1m, a = 5.1318(3) Å, and c = 4.5520(3) Å. Compounds with M = Co and Ni antiferromagnetically order at 11 and 15 K, respectively, whereas the copper compound does not show long-range magnetic order down to 1.5 K. A comparison between the magnetic behavior of the metastable and stable polymorphs was carried out. FeSb2O6 could not be prepared because of the 2Fe2+ + Sb5+ = 2Fe3+ + Sb3+ redox reaction. This electron transfer produces an additional 5s2 shell for Sb and results in a volume increase. A comparison of the formula volume for the stable mixture FeSbO4 + 0.5Sb2O4 with that extrapolated for FeSb2O6 predicted that the trirutile-type FeSb2O6 can be stabilized at high pressures. [ABSTRACT FROM AUTHOR]

Study of the issues of identification, analysis, and comparative assessment of the risks of violations of the safety of the main railway transport infrastructure. The aim of the study: is to develop a methodology for the identification of economic risks of investment projects of construction of mainline infrastructure of railway transport. The object of the study: railway transport enterprises involved in all stages of the life cycle of the mainline infrastructure of railroad transport. The subject of the study: tools and procedures for the identification of economic risks of violations of the security of trunk railway transport infrastructure. In the turbulent global economy, the effectiveness of project management is based on the perception of the human factor as the main in the formation of aggregate uncertainty. Large infrastructure companies should pay special attention to the identification, analysis, and assessment of project risks. One of the key figures in Russia's transport communication, influencing not only domestic traffic flows, but also international logistics chains, is JSC "Russian Railways". Disruptions of the transportation process due to the realization of risks at the main infrastructure facilities of JSC "Russian Railways" predetermine economic consequences both for consumers of services, operators, and infrastructure owners.

The possibility of reuse of heavy residues (oily sludge) of low-sulfur, highly paraffinic Mangyshlak oils as a basis for fuel with improved environmental characteristics for engines to marine, river and railway transport, gas turbine and boiler plants, steam boilers and industrial furnaces was shown. A variant of the joint application of the methods of nuclear magnetic resonance, laser confocal microscopy and rheology for study of micro- and mesoscopic structure and some physicochemical properties of crude oil products has been developed. It has been shown that preliminary heating to 90 ° C leads to disruption of the structure and hydrogen bonds between oil associates and complexes, increasing sample homogeneity due to precipitation of solid impurities, partial removal of water content, air bubbles and dissolved gases. The addition of medium distillate diesel fractions to preliminary heated oil residues will make it possible to obtain a higher quality version of the fuel with a reduced resinous and asphaltene substances, lower pour point, good energy content and low sulfur content. Thus, valuable energy-containing raw materials can be reused. It should also be noted that the reuse of accumulated oil waste will reduce the harmful effects of landfills, will preserve the natural landscape, and will cut the cost of extracting natural resources.

Development and optimization of technologies using nanocomposite materials is one of important areas in modern industrial engineering. In transport industry and in fuel power engineering the use of nanoparticles can optimize fuel consumption, reduce pollutants, and increase aggregate productivity. A special role belongs to carbon nanomaterials, primarily to multi- and single-walled carbon nanotubes, since, beside the improvement of fuel characteristics, they can be completely utilized during combustion. Application of nanoparticles requires the preparing of stable suspensions suitable for various technological processes. In this work by the help of NMR spectroscopy the dispersing of nanomaterial by block copolymers was considered: by poloxamers (P184 and P407) in aqueous medium and by poloxamine (Diproxamine-157) and its mixture with liquid poloxamer P184 in oil medium. Good dispersibility of nanomaterial and stability of aqueous dispersions obtained with the help of poloxamers have been shown. Also, it has been established that pure liquid reverse-sequential poloxamines can be used to create oil-soluble dispersions of nanomaterial. Possible mechanisms to prevent reagglomeration by the help of poloxamines have been considered.

We report the revised crystal structure, static and dynamic magnetic properties of quasi-two dimensional honeycomb-lattice silver delafossite Ag3Co2SbO6. The magnetic susceptibility and specific heat data are consistent with the onset of antiferromagnetic long range order at low temperatures with Néel temperature TN∼ 21.2 K. In addition, the magnetization curves revealed a field-induced (spin–flop type) transition below TN in moderate magnetic fields. The GGA+U calculations show the importance of the orbital degrees of freedom, which maintain a hierarchy of exchange interaction in the system. The strongest antiferromagnetic exchange coupling was found in the shortest Co–Co pairs and is due to direct and superexchange interaction between the half-filled xz + yz orbitals pointing directly to each other. The other four out of six nearest neighbor exchanges within the cobalt hexagon are suppressed, since for these bonds the active half-filled orbitals turned out to be parallel and do not overlap. The electron spin resonance (ESR) spectra reveal a broad absorption line attributed to the Co2+ ion in an octahedral coordination with an average effective g-factor g = 2.40 ± 0.05 at room temperature and show strong divergence of the ESR parameters below ∼150 K, which implies an extended region of short-range correlations. Based on the results of magnetic and thermodynamic studies in applied fields, we propose a magnetic phase diagram for the new honeycomb-lattice delafossite. [ABSTRACT FROM AUTHOR]

We report the revised crystal structure, static and dynamic magnetic properties of quasi-two dimensional honeycomb-lattice silver delafossite Ag3Co2SbO6. The magnetic susceptibility and specific heat data are consistent with the onset of antiferromagnetic long range order at low temperatures with Néel temperature TN∼ 21.2 K. In addition, the magnetization curves revealed a field-induced (spin–flop type) transition below TN in moderate magnetic fields. The GGA+U calculations show the importance of the orbital degrees of freedom, which maintain a hierarchy of exchange interaction in the system. The strongest antiferromagnetic exchange coupling was found in the shortest Co–Co pairs and is due to direct and superexchange interaction between the half-filled xz + yz orbitals pointing directly to each other. The other four out of six nearest neighbor exchanges within the cobalt hexagon are suppressed, since for these bonds the active half-filled orbitals turned out to be parallel and do not overlap. The electron spin resonance (ESR) spectra reveal a broad absorption line attributed to the Co2+ ion in an octahedral coordination with an average effective g-factor g = 2.40 ± 0.05 at room temperature and show strong divergence of the ESR parameters below ∼150 K, which implies an extended region of short-range correlations. Based on the results of magnetic and thermodynamic studies in applied fields, we propose a magnetic phase diagram for the new honeycomb-lattice delafossite. [ABSTRACT FROM AUTHOR]

We have studied the effect of Er concentration on the visible and IR luminescence of (YEr)OS solid solutions in the range 450-1600 nm under excitation at a wavelength of 365 nm. [ABSTRACT FROM AUTHOR]