In this work, scanning electron microscopy and X-ray energy dispersive analysis methods were used to study the morphology and composition of dust and dirt that accumulates on the protective glass surface of the photovoltaic module. These modules are located in the local Tashkent area. It is shown here that the sizes of the inorganic particles varied from 2 μm to 75 μm, while the organic particles are up to several millimeters in size. The inorganic dust component consists of particles with different shapes, while the organic dust is characterized by a fibrous structure in which holes and micropores were found. Elemental composition studies have shown significant differences between samples of inorganic and organic origin. Analysis of the elemental composition showed a high weight fraction of oxygen, indicating its chemical bonding in compounds with silicon, calcium, carbon and iron, which suggests the presence of these elements in the form of stable oxides. It is shown that organic pollution components contains oxygen, carbon, nitrogen and phosphorus, which may indicate a high content of organic compounds in the form of plant fibers and oxides; the last two elements are characteristic of bird waste products. These studies that were carried out to determine the morphological features and to quantitatively analyze the composition of the dust and dirt that accumulates on the protective glass surface of the photovoltaic module allows us to conclude that the search for methods for preventing and cleaning this accumulation on the front surface of the modules should be targeted for particles of inorganic origin with longitudinal dimensions of up to 30 μm and at the same time it is necessary to look for ways to deterio- rate their adhesive properties. Another important conclusion in the case of organic pollution is that the organic compounds found in bird droppings are in a water-soluble form, which allows you to clean the surface of photovoltaic modules without the use of special detergents.

According to the Technical Requirements for Generating Equipment of Participants in the Wholesale Market of the Unified Energy System (UES) of Russia, "from 2016 to participate in the general primary frequency regulation (PRCF), the maneuverable characteristics of generating equipment of nuclear power plants with VVER reactors put into operation before 2009 should ensure frequency deviations guaranteed realization of the required primary power for loading up to 2% of the nominal electric power. For this, the current capacity of the reactor installation should be maintained at a level of not more than 98% of the nominal thermal power. The fulfillment of this requirement signifi- cantly reduces the installed capacity utilization factor (CUF) of reactor plant.

In addition, at present in the UES of the Russian Federation there is a tendency towards an increase in the deficit of peak and half-peak capacities. The majority of fossil fuel-fired thermal stations are switched to the half-peak mode, which negatively affects their efficiency and reliability. In addition, the rise in price of natural gas makes it more profitable to sell it abroad instead of burning at power plants. On the other hand, an increase in the share of nuclear power plants is observed in the UES, which exacerbates the problems associated with the passage of minima and maxima of the daily load in the power system, due to the economically and technically justified need to load NPPs with maximum CUF.

The authors developed an approach to solving this problem by combining NPPs with an environmentally friendly energy source - an autonomous hydrogen complex (AHC), which includes thermal batteries and an additional multi- functional steam turbine unit. The developed energy complex will allow energy to be accumulated during hours of minima load in the power system due to the electrolysis of water to produce hydrogen and oxygen, as well as the accumulation of hot water in the storage tanks. The accumulated energy can be used to generate super-nominal electrici- ty to cover the half-peak load zone in the power system. In addition, the presence of a low-power steam turbine installation will ensure uninterrupted power supply to consumers of their own needs at the NPP by using the energy of the residual heat from the reactor when the station is completely de-energized.

Based on the proposed energy complex, a method has been developed to ensure the participation of NPPs in the PRCF in an energy system with a constant CUF. To assess the effectiveness of the proposed solution, a methodology for thermodynamic analysis of the energy complex based on the combination of NPPs with AHC was developed. The dependence of the required hydrogen fuel consumption and the efficiency of using off-peak electricity on the temper- ature of the feed water supplied to the hydrogen-oxygen steam generator from the hot water tanks is constructed.

Based on the results obtained, the technical and economic efficiency of the developed energy complex is considered. The accumulated net present value was determined depending on off-peak electricity tariffs with three variants of the forecast dynamics of the half-peak electricity tariff, taking into account natural gas savings, reduced investment in NPP safety systems and the economic effect of ensuring the participation of NPPs in the PRCF with the plant load at 100%.

This paper considers the production of biohydrogen in a two-stage process of anaerobic bioconversion of organic matter (OM) of liquid waste with recirculation of digester effluent into an anaerobic bioreactor for dark fermentation (ARDF). The values of the average biohydrogen specific yield (BSY) and the average volumetric biohydrogen production rate (VBPR) were obtained at 4 recirculation ratios (RR) of the digester effluent (1, 1.1, 1.18, 1.25) and 2 hydraulic retention times (HRT) ( 1 and 2.5) in ARDF. Organic loading rate (olr) varied from 7.96 to 21.6 g OM / (l ∙ day). The pH value in ARDF practically did not depend on RR and HRT, and ranged from 3.8 to 4.16. The maximum BSY was 0.108 l / (day ∙ g OMin) with a RR of 1.11 and a HRT of 2.5 days. The maximum VBPR was observed at RR 1 and HRT 1 day and amounted to 1.67 l / (l ∙ day). The methane content in biohydrogen-containing biogas at modes providing maximum BSY and VBPR was no more than 0.01%, but it increased sharply at higher values of RR and HRT. The hydrogen content in biogas averaged 50-52% for all combinations of RR and HRT, but it sharply decreased to 46.7% with HRT 2.5 and RR 1.25. In general, with RR 1.11 and HRT 1 day, an increase in BSY by 9.05% was observed, while the VBPR decreased by 1.04% (compared with RR 1.0 and HRT 1 day). In general, the experi- mental data obtained allow us to speak of a RR equal to 1.11 as the most effective for both HRTs in the studied range of RR.

The study of the literature data showed that yttrium is encapsulated in fullerene molecules in the form of metal atoms, clusters of nitrides, carbides, sulfides and other compounds. Endohedral metallofullerenes are capable of encapsulating up to four metal atoms. In the molecules of these compounds, the metal atoms are positively charged due to the transfer of an electron from the endohedral metal atom to the fullerene carbon cage. First of all, the main experimental and theoretical achievements described in early (up to 2000) works are considered. Achievements in the production, separation (isolation) and various spectroscopic characteristics of endohedral metallofullerenes have been thoroughly studied in an attempt to elucidate their structural, electronic, and solid-state properties. It is shown that endohedral metallofullerenes in electrical conductivity can be metals, semiconductors with small gaps, or insulators, depending on the size of the fullerene, the type and number of encapsulated metal atoms. Other electronic and magnetic properties of metallofullerenes are also interesting. Also, some promising applications of metallofullerenes are considered.
In addition, when analyzing the literature on the synthesis and properties of metalloendofullerenes, a very large number of publications related to the exohedral functionalization of metallofullerenes attracts attention.
First of all, it should be noted that the main problem hindering the development of science, technology and the use of fullerenes, endohedral metallofullerenes and nanotubes was the difficulty of obtaining high-purity samples. When metals are introduced into the electric arc process, the situation becomes more complicated due to the presence of many isomers of both fullerenes and endohedral metallofullerenes. Exohedral functionalization helps to solve the problem of separation of synthesis products, on the one hand, and leads to the production of substances with new useful properties and potential applications in materials science and medicine.
It is noted that currently the most productive and widespread method for the production of endohedral fullerenes is the electric arc process. The quantitative and qualitative output of metallofullerenes is significantly influenced by the conditions of the process in the reactor.

The most affected regions by the COVID-19 outbreak are megacities. One of the most important environmental problems in these cities is air pollution. During the lockdown period, an improvement in air quality was observed in many metropolitan cities based on air pollutants. In this study, Istanbul province was chosen due to its demographic structure. In Turkey, many precautions such as lockdowns have been implemented against COVID-19 starting from March 15, 2020. As these measures change people's lifestyles and habits, anthropogenic emissions are expected to reduce. In previous studies, the relationships between air pollution and meteorological variables such as wind speed and direction, pressure and humidity have been proved. Therefore, in this study, it was decided to examine the meteorological variables mentioned above and air pollutants together. In the studied period, Controlled lockdowns were imposed intermittently in 1/3 of April. The comparison of air pollutant values belonging to lockdown and nonlockdown days were examined in consideration of the meteorological variables. PM₁₀, CO, NO₂, SO₂ and O₃ pollutant datasets taken from Ministry of Environment and Urbanization for several points in Istanbul and meteorological charts for the same dates taken from various sources were evaluated.

COVID-19 period changed daily-life such as precautions, restrictions and most importantly lockdowns in almost every country. Turkey has been one of the struggling countries especially the period after 15th of March, 2020. As many scientists from all over the world have been researching coronavirus’ medication, COVID-19’s possible relations have been also investigated. These relations are mostly focused on the respiratory system and immune system as well as human-to-human transmission. Air pollution is also known as a threatening factor for human life, furthermore China’s reduced air pollution is shown in the COPERNICUS Sentinel 5P and TERRA/MODIS AOD images during the lockdown process. In this study, it is aimed to analyze the air pollution in Istanbul while life in Turkey has almost stopped. Ministry of Environment and Urbanization’s PM₁₀, PM_2.5, NO₂, CO, SO₂ and O₃ pollutant datasets are taken into consideration as two different periods which represent the time before the lockdown from Jan 1st to March 15th as first period and during the lockdown from March 16th to May 31st as second period for Istanbul is analyzed. These periods are also examined for the same dates in 2018 and 2019. Results are important to find out how air pollution has decreased in Istanbul during coronavirus lockdown period, especially 40% decrease of NO2 pollutant in contrast with 2018 and 2019 dataset for the same period of the year in 2020.

Nowadays the increased attention in the Russian Federation has been paid to the coal ash handling issue. This is due to a number of reasons: the tightening of environmental regulation with the transition to the principles of the best available technologies, the greening of coal-fired power industry, the depletion of ash dumps of coal-fired TPPs, etc. Today, the average age of coal-fired TPPs is approximately 45-50 years, which significantly affects the technical and environmental performance of the TPP ash removal system. Conventional technical solutions using hydraulic ash removal systems for transporting coal ash slurry at TPPs are technically outdated, uneconomical and environmentally ineffective. Currently, about 1.5 billion tons of coal ash have been accumulated at the ash dumps, and these figures are growing every year. In this regard, the main problem of coal-fired TPPs is the elimination of the accumulated environmental damage, which can be solved only by implementing large-scale projects for the integrated processing of coal ash to obtain products in demand.

The article provides an overview and analysis of the main regulatory documents in the field of coal ash handling, including the features of regulatory technical acts, problems that reveal the gaps in the existing regulatory framework and the impossibility of its practical application; proposals for the development of the missing and correct normative and technology-based documents needed to form the technological basis for manufacturing the products from coal ash. The article presents the experience of the Russian company Ecomett-Luch LLC in the integrated processing of coal ash from Primorskaya State District Power Plant regarding the processing of coal ash products of the current output, as well as the wastes disposed off, obtaining various products demanded both in Russia and abroad. The article contains a diagram showing the dynamics of the investment process of developing waste-free production at coal-fired TPPs based on many years of the authors’ experience in the field of coal ash handling.

Traditionally, determination of static load characteristics is one of the main stages in the preparation of a design model of an electric power system. It is especially important to correctly take into account energy-intensive industries, which make a huge contribution to the formation of these characteristics. In particular, the increased interest in hydrogen technologies observed in the world, as one of the most promising high-tech areas of energy development, and an increase in the share of the installed capacity of generation facilities based on renewable energy sources determine the prospects for the development of hydrogen production by the electrolysis of water. Accordingly, a significant increase in the scale of application of hydrogen technologies, in particular in accordance with the EU Hydrogen Strategy for the production of "green" hydrogen, determines the problem of forming correct mathematical models of these devices in terms of planning modes, analyzing them influence on the parameters of electric power systems. Due to the complexity of the physical experiment, especially significant increase or decrease the voltage in a node of an electric power system, it seems relevant to simulate a part of the consumer in order to identify their electric power characteristics. In this paper the results of correction of the static load characteristic of electrolysis tank, which is widely used in the production of aluminum, are presented. Analysis of these results, obtained by MATLAB software, is carried out by using the least squares method to regress the data and to obtain a polynomial function of static load characteristics. According to this analysis, the static load characteristics of electrolysis tank have a parabolic dependences of active and reactive power, the position of which is determined by the parameters of the supply scheme and current-voltage characteristic of rectifiers. For instance, it shifts the vertex of the parabolas, which should be taken into account to improve the accuracy of the calculation scheme.