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Due to the absence of experimental data for constructing the phase diagram of a liquid and gaseous mixture of hydrogen with oxygen, it is constructed by modeling. Model diagrams previously predicted (Deiters et al., 1993) by two methods (I and II) at pressures up to »100 MPa and a temperature up to »100 K have significant differences, which are considered by the authors as an approximate measure of the uncertainty of the knowledge of the real phase diagram of this mixture. In this paper, the phase diagram of a mixture of hydrogen with oxygen is determined using the previously proposed modified van der Waals model for individual and mixed compounds. Calculations were performed in two (A, B) variants differing in the binary interaction parameter. To control these variants, they were used to construct model diagrams of mixtures of hydrogen with nitrogen, argon, and methane for which there are experimental data in the range of pressures and temperatures comparable to those mentioned above for the mixture of hydrogen and oxygen. Variant B is more realistic as it is in better agreement with experiment compared with variant A. The phase diagram calculated by method B for a mixture of hydrogen with oxygen is close to the calculation by method I, which indicates that it is more realistic than method II.

To investigate the mechanism of the flame-vortex interaction induced by an obstacle, a numerical research of premixed methane-air flame dynamics in an obstructed chamber is described. Numerical simulations are performed with the OpenFOAM open-source CFD code. The simulation images show that the flame propagation process can be divided into four typical stages. A series of instabilities are captured in the simulation during flame propagation. More importantly, the numerical results demonstrate that a longer obstacle allows a sufficient accelerating time, which can give rise to a higher explosion overpressure and faster flame tip speed.

The laminar burning velocities of a stoichiometric CH₄-N₂O mixture diluted with N₂ [30 ÷ 60 % (by volume)] at various initial pressures (1 ÷ 10 bar) and various initial temperatures (273 ÷ 423 K) are obtained by numerical modelling of their premixed adiabatic flames. The modelling is performed with the Cosilab package using the GRI-Mech 3.0 mechanism based on 53 chemical species and 325 elementary reactions. The calculated laminar burning velocities are compared with available literature data. The influence of the initial conditions (pressure, temperature, and N₂ concentration) of CH₄-N₂O-N₂ mixtures on the laminar burning velocities, maximum flame temperature, heat release rate, and peak concentrations of the main reaction intermediates is investigated and discussed. Using the correlations of the laminar burning velocities with the initial pressure and the average flame temperature, the overall activation parameters of CH₄-N₂O oxidation are determined.

Eutrophic peat(y) (Hypereutric Sapric Histosols) pyrogenic soils on the hammock and hollow of phytogenic microrelief were studied 20 years after a large fire in the swamp spruce forest ( Picea obovata Ledeb.) of the eastern macroslope of the Kuznetsk Alatau. Currently, the burned area occupied by dense shrub-sedge-green moss birch forest ( Betula pubescens Ehrh.). Pyrogenic peat soils (mechanical and chemical underburning), differentiated by elements (groups) of the microrelief, are characterized by a pronounced intra-group spatial heterogeneity of physical and chemical properties ( C_V 21-39 %). However, according to the average indicators of most characteristics, except for moisture of peat, the soils of hammock and hollow do not significantly differ from each other. The content of ash substances is in the range of 52.5-53.5 %, carbon - 20.4-21.2 %, the bulk density is 0.29-0.31 g/cm³, the moisture of peat soil bulk is 49-60.8 %, the soil reaction is mainly slightly alkaline. The process of passive smoldering (below the ignition point) of a peat deposit is accompanied by an additional loss of carbon, which was calculated directly from the element using a natural experiment before and after the fire. The loss value is characterized by high variability ( C_V 34-42 %) due to a variety of thermal effects caused by environmental factors and fire features. Lower level of carbon loss and its weak mosaicity have been objectively identified for the hammock relative to the hollow. Additional carbon loss - limit, average (standard deviation) is: in pyrogenic soils of hammock 1.4-4.4, 2.98 ± 1.05, in the hollow - 0.4-5.7, 3.71 ± 1.57 kg/m². On average, this corresponds to 33.5 t/ha in the burned area, which is equivalent to 122.9 t/ha of CO₂ released into the atmosphere. The intensity of carbon losses in the process of passive smoldering is approximately 3-4 times lower compared to the burning of a peat deposit.

The problem of forest fires in the Far East has always been very acute. The forest fund of the Far Eastern Federal District (Far Eastern Federal District) as a whole is characterized by a high fire hazard and burnability due to the predominance of coniferous species and the complex composition of stands, the presence of various ecosystems and communities, including harems and meadow phytocenoses, as well as a number of geomorphological and climatic features. High classes of natural fire danger cause a greater probability of fires compared to the rest of the Russian Federation. At the same time, the most significant reserves of wood, which is one of the most valuable components of the Far Eastern export, are concentrated here. The article analyzes the dynamics of the area and number of forest fires, as well as the loss of wood on the root for the period from 2009 to 2020 in the Russian Far East, summarizes the reasons for the aggravation of the forest fire situation in recent years and provides general recommendations for reducing its intensity. The results of the study show significant fluctuations in the area and number of forest fires in different periods with an increase in 2016-2020. The average annual area of forest fires in the Far Eastern Federal District is about 2.5 million hectares per year. Over a 12-year period, the annual loss of wood stock is 10.5 million m³. The most affected regions are the Republics of Sakha (Yakutia) and of Buryatia, the Amur Oblast. The causes of fires, both in 1973-2004, and now mainly remain anthropogenic factors. In the zone of cedar-broad-leaved forests, 93 % of forest fires are caused by humans. The solution to the problem of forest burning is not simple and unambiguous and combines a whole set of measures necessary for adoption at the federal and regional levels.

The changes in the physico-chemical parameters of Scotch pine Pinus sylvestris L. wood were studied at an early stage of a fungal infection development in it using the methods of IR-Fourier spectroscopy and scanning electron microscopy (SEM). Analysis of SEM-images of locally damaged wood showed the presence of hyphae both in the intercellular space and in the lumens of single tracheids. From the comparison of the results of analyses of damaged and healthy wood, a number of parameters of the IR spectra were established - a change in the ratio of the absorption intensity at characteristic frequencies (wave numbers, cm^-1) for polymers of wood substance (hemicellulose, cellulose, lignin) and fungi (chitin and glucans) I _1512/898, I _1512/1157, I _1512/894, I _1647/1551, I _1695/1533, I _1620/1564, which allows identifying the presence and degree of exposure to fungal infection on wood. A new version of the assessment of changes in the structure of the wood substance is presented, which consists in a comparative analysis of the second derivatives of the IR absorption spectra of sound and damaged wood. The method significantly improves not only the visualization of changes in the spectra, but also allows to more accurately determine the «addresses» of the impact of a fungal infection on the wood substance by the intensity and frequency of the absorption bands. In addition, it can be used to monitor the appearance of nitrogen-containing compounds because of the presence of fungi. The implemented methodological techniques indicate the possibility of using radial cores in the work for the purpose of conducting their conjugate analysis, «linking» the results of IR-Fourier spectroscopy to the parameters of the annual rings and, in general, to chronologies, as well as correlating them with the morphological and anatomical structure of the annual ring and individual tracheids according to scanning electron microscopy data. The proposed approach to the diagnosis of wood damage at an early stage of the development of a fungal infection is effective, rapid and does not require complex sample preparation

Urban environment contains a broad variety of factors and this is where all living organisms are exposed to heavy stresses. Green plant serve as a natural «air filters» and are among the first to respond to negative changes of growth conditions. Crowns are the tree parts first to respond to negative changes of growth conditions by growing thinner, partially defoliated, and leaves’ (needles’) becoming heavily damaged. We presented the 1999 and 2020 inventories of the woody species of Central Park. Our analysis of the inventory results for species composition revealed thirty three species of trees and shrubs, seven conifer and twenty six deciduous. Judging by the condition of the crowns, the health of the majority of the park trees was poor to very poor. Among deciduous, ash-leaved maple Acer negundo L., balsam poplar Populus balsamifera L., aspen Populus tremula L. and Chinese elm Ulmus parvifolia Jacq. exhibited the poorest health. Tree health has improved, as compared to 1999, due to appropriate treatments and planting of young individuals. We also studied species compositions of invertebrate woody plant feeders and pathogenic fungi. We found that the amount of dust accumulated on the leaves of the trees in the park for a short rainless period was 8.6 to 9.8 times that of a background stand. In 2020, dust precipitated on leaves was 1.6 - 3.4 times less than in 1999. Dust accumulating capability of trees is much dependent on weather conditions. We used the results obtained to word our suggestions for improving the green spaces of the park.

For the key part of the territory of the Sayano-Shushensky Biosphere Reserve, located in the West Sayan mountains, the results of assessing the current state of natural stands of the Siberian stone pine Pinus sibirica Du Tour and its renewal under the canopy of the mother forests for the period from 1984 to 2015 are presented. Based on remote sensing data, cartographic materials of forest inventory and forest planning, their statistical processing and geoinformation analysis, the regularities of the spatial placement of the Siberian stone pine forests and the Siberian larch Larix sibirica forests with a mixture of the Siberian stone pine were revealed in the basin of the Sanzu River (Khemchik mountain ridge). The description and comparison of the main forest inventory characteristics of the Siberian stone pine from the position of the main and secondary species in the composition of the stands is given. It is noted that the process of regeneration under the forest canopy for different high-altitude belts and types of forest does not proceed in the same way. However, the trend of changing the breed in the forest is also obvious: cedar replaces larch and expands the boundaries of potential growth. It is established that the Siberian stone pine retains a stable position and has even expanded the area of domination over the past 30 years both at the upper and lower limits of growth. This is confirmed by the cartographic materials and tables provided. The priority of the environmental-forming functions of mountain the Siberian stone pine forests over forest-raw is justified.

Forest ecosystems play an essential role in climate stabilization, and the study of their capabilities in this aspect is of paramount importance. On the other hand, the current climatic shifts cause changes in their biological productivity, which, in turn, affects the biosphere function of forests. The study of the relationship between the biomass of trees and stands and hydrothermal indicators, in particular temperature and precipitation, is carried out mainly at the local or regional levels, often for indicators that are depersonalized by age, morphostructure of the forest, and also without taking into account the species composition. How climate changes affect the biomass of trees in transcontinental gradients is unknown today. The objective of this study was (a) to verify the operation of the law of the limiting factor at the transcontinental level when modeling changes in the biomass of trees of forest-forming species of Eurasia in relation to geographically determined indicators of temperatures and precipitation, and (b) to test the possibility of using the constructed climate-conditioned models of tree biomass in predicting temporal changes in tree biomass based on the principle of space-for-time substitution. As a result of the implementation of the principles of the limiting factor and space-for-time substitution, a common pattern has been established for the main tree species (genera): in sufficiently moisture-rich climatic zones, an increase in temperature by 1 °C with a constant amount of precipitation causes an increase in aboveground biomass, and in non-deficient zones - its decrease; in warm climatic zones, a decrease in precipitation by 100 mm at a constant average temperature in January causes a decrease in aboveground biomass, and in cold climatic zones - its increase.

A critical analysis is provided for the article: D. N. Klevtsov, O. N. Tyukavina Uglerododeponiruyushchaya sposobnost’ nadzemnoy fitomassy kul’tur sosny obyknovennoy (Pinus sylvestris L.) srednetaezhnogo lesnogo rayona (Carbon-depleting ability of aboveground phytomass in Scotch pine ( Pinus sylvestris L.) plantations of medium-taiga area) // Vestn. KrasGAU (Bull. Krasnoyarsk St. Agr. Univ.). 2018. N. 6 (141). P. 221-224 (in Russian with English title, summary and references).