Tatiana L. Lepkova

In this work, hierarchically porous composites were prepared in the form of activated carbon cloth (CC) Busofit T–1–055 filled with an electrically conductive polymer, polyaniline (PANI), for use as pseudocapacitive electrodes of electrochemical supercapacitors (SCs). CC fibers have high nanoporosity and specific surface area, so it was possible to deposit (via the chemical oxidative polymerization of aniline) a significant amount of PANI on them in the form of a thin layer mainly located on the inner surface of the pores. Such morphology of the composite made allowed the combining of the high capacitive characteristics of PANI with the reversibility of electrochemical processes, high columbic efficiency and cyclic stability rather typical for carbon materials of double-layer SCs. The highest capacitance of composite electrodes of about 4.54 F/cm² with high cyclic stability (no more than 8% of capacity loss after 2000 charge–discharge cycles with a current density of 10 A/cm²) and columbic efficiency (up to 98%) was achieved in 3 M H₂SO₄ electrolyte solution when PANI was synthesized from an aniline hydrochloride solution with a concentration of 0.25 M. Trasatti analysis revealed that 27% of specific capacitance corresponded to pseudocapacitance, and 73% to the double-layer capacitance.

Grain boundaries (GBs) can be wetted by a second phase. This phase can be not only liquid (or melted), but it can also be solid. GB wetting can be incomplete (partial) or complete. In the case of incomplete (partial) wetting, the liquid forms in the GB droplets, and the second solid phase forms a chain of (usually lenticular) precipitates. Droplets or precipitates have a non-zero contact angle with the GB. In the case of complete GB wetting, the second phase (liquid or solid) forms in the GB continuous layers between matrix grains. These GB layers completely separate the matrix crystallites from each other. GB wetting by a second solid phase has some important differences from GB wetting by the melt phase. In the latter case, the contact angle always decreases with increasing temperature. If the wetting phase is solid, the contact angle can also increase with increasing temperature. Moreover, the transition from partial to complete wetting can be followed by the opposite transition from complete to partial GB wetting. The GB triple junctions are completely wetted in the broader temperature interval than GBs. Since Phase 2 is also solid, it contains GBs as well. This means that not only can Phase 2 wet the GBs in Phase 1, but the opposite can also occur when Phase 1 can wet the GBs in Phase 2. GB wetting by the second solid phase was observed in the Al-, Mg-, Co-, Ni-, Fe-, Cu-, Zr-, and Ti-based alloys as well as in multicomponent alloys, including high-entropy ones. It can seriously influence various properties of materials.

This paper looks at the gas emissions balance in the wind corridor along the wind direction. An equation was found that describes the dependence of the emissions concentration inside the wind corridor along the wind direction when the concentration inside the wind corridor at the right angle to the wind flow is uniform. The authors propose a system of diffusion equations and its solution in a quasi-steady state for determining the concentration field in the whole space. It is shown that the transfer distance ratio has an approximate correspondence to the diffusion scope in the overall concentration. The diffusion scope was found to not exceed 0.01 %. And it becomes even lower as the wind speed rises and the time interval extends for which the diffusion transfer is analyzed. That’s why the wind transfer process can serve as a sufficient factor of changing concentration. To create a mathematical image of the concentration field for a given pollutant in the geographical coordinates, apart from the emission intensity and the chemical activity of such pollutant in air, one needs to know the wind rose of the region where the production site is situated. This helps determine the relationship between the maximum concentration of the pollutant and the distance (from the source of emission) in eight geographical directions, in eight points of the wind rose. It is noted that the use of the wind rose for mapping full information on the distribution of each pollutant helps superpose the fields of the maximum allowable concentrations (maximum hazard) of each pollutant with the geographical map of a particular production site. A relationship was defined between the maximum concentration of the pollutant and the source of emissions. The paper also describes the results of a study that looked at the transfer of emissions in air and determined the maximum distance for the maximum allowable concentration of sulphur dioxide emitted by Nornickel’s Norilsk site. It is demonstrated that when a light northeast wind blows (the average speed is around 3 m/sec), the SO2 concentration in the northeast sector of the wind rose along the wind path is likely to exceed the maximum allowable mean daily concentration as far as 2,500 km from the site.