Russian Journal of Physical Chemistry B最新文献

An extended version of the previously developed computational procedure SPECTRUM is presented, which allows us to calculate the radiation characteristics of a shock-heated gas, taking into account the decrease in the radiation intensity in an absorbing medium. The procedure is based on a line-by-line calculation of the emission and absorption spectra of the atoms and molecules that make up the studied gas mixture. When calculating the emission spectra of atoms and molecules, the values of spectroscopic constants are taken from well-known databases. The results of calculating the time-integrated spectral characteristics of shock-heated air are compared with the available experimental data obtained in the ultraviolet, visible, and infrared regions of the spectrum.

Spin probe electron paramagnetic resonance spectroscopy was applied to estimate release kinetic patterns from globules formed in solutions of thermoresponsive polymers poly-N-isopropylacrylamide (PNIPAM) and graft copolymer based on N-isopropylacrylamide and oligolactide (P(NIPAM-g-PLA)) containing (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) spin probe as a drug model. It is shown that the main mechanism of TEMPO release from globules of thermoresponsive polymers in aqueous solutions above LSCT is Brownian diffusion.

Criegee intermediates, which are the result of ozonolysis of alkenes, play a key role in many chemical and physical processes in the Earth’s atmosphere. Their reactions with various atmospheric compounds are responsible for formation of hydroxyl radicals, atomic oxygen and hydrogen, sulfuric and nitric acids, and other chemically active radicals and molecules. In this work we have considered collisional-induced chemical reactions between three simple Criegee intermediate molecules: CH₂OO, CH₃CHOO, and (CH₃)₂COO with methane, which is a well-known active greenhouse gas. Methane concentration rapidly growths last decades that causes serious concern to the global scientific community. It was established that reactions between methane and Criegee Intermediates can follow through two main routes. One of them occurs over exchange of oxygen and hydrogen atoms upon collision and leads to the formation of methanol. Another one pass through the formation of an intermediate complex with a deep energy minimum, and produces OH radicals and a variety of other products, among which are acetone, acetaldehyde, formaldehyde, propaldehyde, methanol, water molecules, and others. In this work, the both kinds of the reactions have been studied, and the relative reaction rates of both pathways have been compared.

Every year, metallurgical plants emit hundreds of thousands of tons of harmful substances into the atmosphere. The remote sensing of flue gases from the chimneys of metallurgical plants is an urgent task for both industrial enterprises themselves and the enviromental control systems of nearby settlements. In this study, based on the results of the remote optical monitoring of emissions from chimneys of metallurgical plants of the PJSC “MMC ‘Norilsk Nickel’s’,” Polar Division, the concentration of sulfur dioxide in flue gases is estimated. The measurements are carried out using infrared (IR) Fourier transform spectrometers operating in the 7–13 µm range with a spectral resolution of 4 cm^–1. A new technology for remote optical sensing in the passive mode of flue gases from metallurgical plants is proposed, including measurements both on cross sections of chimneys and plumes.

Due to the increase in radon emanation, the conductivity in the surface layer of air increases, which causes variations in the electric fields in the low atmosphere and according to some hypotheses in the ionosphere. There are well-known proposals on the possibility of using such ionospheric disturbances as precursors of earthquakes. In this study, the ionospheric electric fields are calculated in the framework of a quasi-stationary model of the conductor consisting of the atmosphere, including the ionosphere. The consequences of the paradoxical point of view on the decrease in the conductivity of surface air with an increase in radon content are also considered. It is shown that even with extreme radon emanation, the obtained calculated perturbations of the ionospheric electric field are three to four orders of magnitude smaller than the supposed precursors of earthquakes.

To identify promising areas for the search for high-energy materials (HEMs), there is an urgent need for a comprehensive analysis of the energy potential of compounds of various classes. This paper studies the energy potential of some organic compounds containing the –N=N(O)–C(NO₂)₃ fragment in their structure as plasticizers of a polymeric binder in solid composite propellants. Nine trinitromethyl-ONN-azoxy-derivatives of furazan and one similar methane compound are studied, four of which are actually synthesized substances, the rest are still hypothetical structures. The ballistic efficiency of solid composite propellants of three different types (without metal, with aluminum, and with aluminum hydride (AH)) in which one of the studied compounds with a trinitromethyl-ONN-azoxy fragment acts as a plasticizer of the polymer binder is assessed. The values of its enthalpy of formation and density are determined by calculation. A comparative analysis of the ballistic efficiency of such propellants with similar compositions containing the most powerful of the currently considered energy-intensive components (nitroglycerin, tetranitromethane, or dinitrofurazan) as a plasticizer shows that practically all the studied representatives of the class of trinitromethyl-ONN-diazene oxides are significantly superior in terms of ballistic efficiency to the reference plasticizers.

The parameters of decomposition and combustion of reed plants, which characterize the combustible material and the material required for the physical and mathematical modeling of the occurrence and development of a fire, as well as determining the risk of its consequences, are formulated. According to the results of thermogravimetric analysis (TGA), the content of the main components in the leaves and stem of the plant is estimated, and the mechanism and parameters of the macrokinetics of their thermooxidative decomposition and pyrolysis are determined.

This article is aimed at developing innovations in the field of producing hybrid polymer nanodisperse materials and studying their structural, thermodynamic, and physical and mechanical properties. Filling the ethylene-octene copolymer (EOC) with Ni nanoparticles and basalt scales (BSs) increases the elasticity of the composite by a 25% and also causes an increase in strength by 15%. The results open the possibility of evaluating the influence of the chemical nature, size, and content of different kinds of fillers on improving the thermostability and elasticity of the new hybrid polymer nanomaterials.

This paper is a theoretical study of the piezoresistivity of germanene nanoribbons (GeNRs) of various structural modifications (arm-chair and zig-zag) with acceptor structural defects. Gallium atoms were chosen as impurities. A phenomenological expression for the band structure of nanoribbons (NRs) deformed by tension and compression is proposed. The dependencies of the longitudinal component of the elastic conductivity tensor on the relative deformation of tension and compression, the concentration of impurities, and the width of the NR are analyzed.