Upper limits on the isotropic diffuse flux of cosmic PeV photons from Carpet-2 observations

Isotropic diffuse gamma-ray flux in the PeV energy band is an important tool for multimessenger tests of models of the origin of high-energy astrophysical neutrinos and for new-physics searches. So far, this flux has not yet been observed. Carpet-2 is an air-shower experiment capable of detecting astrophysical gamma rays with energies above 0.1 PeV. Here we report the upper limits on the isotropic gamma-ray flux from Carpet-2 data obtained in 1999-2011 and 2018-2022. These results, obtained with the new statistical method based on the shape of the muon-number distribution, summarize Carpet-2 observations as the upgraded installation, Carpet-3, starts its operation.Comment: 5 pages, 3 figures, JETPL.cls; V2: references added, version accepted by JETP Letter

PERSPECTIVES OF REMOVING CARBON DIOXIDE FROM FLUE GASES OF THERMAL POWER PLANTS WITH OBTAINING VALUABLE CHEMICALS

Removing carbon dioxide from flue gases with subsequent fixation of CO2 into valuable chemicals is the most effective way of reducing emission of this "greenhouse gas" by thermal power plants. Selecting the direction of CO2 transformation into chemical compounds is dependent on the technology applied for the purification of flue gases (chemisorption, physical absorption, etc.). In the case of using the method of monoethanolamine chemisorption, there is proposed to carry out the hydrogenation of recovered carbon dioxide to obtain formic acid and methyl formate. When removing CO2 from flue gases by the method of physical absorption, there is the most appropriate considered the transformation of organic carbon dioxide into organic carbonates (propylene carbonate, glycerol carbonate)