Selection of Elements at the Dissolution of Heat Resistant Nickel Alloys in Mineral Acid Solutions

Thermodynamic modeling of the interaction of a heat-resistant nickel alloy containing refractory rare metals with hydrochloric, sulfuric and nitric acids with a temperature change in the range of 20-100 ∘ C and a concentration of 50 to 150 g / dm3 at a pressure of 1 atm was carried out. The thermodynamic assessment data were confirmed in experiments on the anodic dissolution of the alloy in sulfate solutions. According to the results of x-ray phase analysis of the sludge, it was revealed that tungsten in the form of a solid solution in nickel passes to this product. Also, tantalum and niobium pass into the slurry in the form of oxides. Mostly, Re, Co, Cr passed into the electrolyte solution. The results of the study can serve as a scientific basis for the development of promising technologies for processing metal waste from heat-resistant alloys. Keywords: thermodynamic modeling, heat resistant nickel alloy, rare elements, mineral acids, dissolutio

Антропогенное влияние на микроклимат и оледенение Кунгурской Ледяной пещеры в период максимальной туристической нагрузки

The Kungur Ice Cave is visited by thousands of tourists every year, so the question of anthropogenic influence on changing its state is acute. Snow and ice formations are the main attraction of the cave. From the moment of discovery and improvement of the cave, the thickness of glaciation began to depend not only on natural, but also on technical and anthropogenic conditions. First, this is a change in the temperature of the outside air, the annual rise of underground and surface waters (the Sylva River), the construction of inlet and outlet tunnels, artificial ventilation, and the number of tourists. To assess the impact of the flow of tourists on the microclimatic characteristics of the Cave, the staff of the Kungur Stationary Laboratory conducted research during the period of maximum anthropogenic load in the summer of 2022. The data analyzed in this article made it possible to clarify that the existing tourist load has an insignificant impact on the microclimate of the Cave. After the passage of each group of tourists, the air temperature in the grottoes slightly increases (by a maximum of 0.1–0.2°C) but is restored during the daytime within 4–12 minutes, and at night the temperature regime is completely restored. The maximum tourist load per day is 825–925 people or more, depending on the operating mode of the Cave. Thus, the visiting regulations and the allowed throughput of the cave are currently chosen correctly. The number of tourists is not so large as to limit the visit to the Cave to protect the ice formations, especially since the first-year ice is renewed every winter.По данным проведённых в летнее время исследований в Кунгурской Ледяной пещере, во время максимальной туристической нагрузки, сделаны выводы об антропогенном влиянии на микроклимат и оледенение пещеры. Рассмотрены основные виды воздействия человека на подземную среду, особое внимание уделено тепловому воздействию на изменение температурного режима и масштаба оледенения в существующих условиях эксплуатации Кунгурской Ледяной пещеры

Random Geometric Series

Integer sequences where each element is determined by a previous randomly chosen element are investigated analytically. In particular, the random geometric series x_n=2x_p with 0<=p<=n-1 is studied. At large n, the moments grow algebraically, n^beta(s) with beta(s)=2^s-1, while the typical behavior is x_n n^ln 2. The probability distribution is obtained explicitly in terms of the Stirling numbers of the first kind and it approaches a log-normal distribution asymptotically.Comment: 6 pages, 2 figure