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This study is developed to estimate the proportion of sorbed water converted to ice and hydrate during the interaction of wet sand samples with methane by NMR relaxometry method. It was demonstrated that a thin film of tightly bound water exists in small pores at the rock-fluid interface. This water does not freeze at the subzero temperatures achieved during the experiment; its quantity remains constant, regardless of the sample's water content. The amount of tightly bound water, as well as the amount of water converted to ice and hydrate, was calculated for all samples. Based on the known hydrate stoichiometry, the amount of methane converted to hydrate was calculated. Based on the obtained data, the optimal water content in the sample was determined, which would result in the greatest amount of hydrate formation.

The attenuation of seismic waves and its components in the Earth's crust of the Mountain Altai Chui-Kurai zone has been studied by the method of code envelope inversion [Sens-Schönfelder, Wegler, 2006]. The analysis used waveforms of earthquakes with a magnitude M_L > 2.5, recorded by a network of stationary and temporary stations of the ASGSR RAS within the studied region. As a result, the contribution of Qi^-1 absorption and Qsc^-1 scattering to the overall Qt^-1 attenuation of the main structures of the region was determined, and the spatial distribution of the Qt parameter, as well as the seismic albedo B₀, was estimated. The dominance of the absorption contribution over scattering in the overall attenuation of seismic waves is shown. The obtained values of the seismic Q-factor parameter make it possible to carry out an accurate calculation of the moments of magnitudes and an assessment of the focal parameters of earthquakes, as well as more accurately calculate artificial accelerograms, etc.

The paper provides a brief overview of methods based on the analysis of natural ambient noises of the Earth (passive seismic exploration methods): methods of spatial autocorrelation, seismic interferometry and spectral ratios of seismic noise components, as well as their application to studying the structure and properties of the upper part of the section in Arctic conditions. The analysis and interpretation of the upper part of the section through pingos in the Arctic zone were carried out using passive seismic methods (spectral component ratios). The resulting two-dimensional sections reflect the horizontal layered structure of the upper part of medium – four main layers are clearly visible on the profiles which may be interpreted as the upper sedimentary layer, the basement layer, and two intermediate layers that differ in velocity characteristics. The section is disturbed by vertical and inclined heterogeneities that extend from faults in the basement to the surface and are characterized by high anisotropy of properties and reduced rigidity. The spatial correlation of the identified subvertical heterogeneities with the position of pingos on the surface suggests that these areas represent weakened zones, possibly fault zones or conductive channels. Based on the results of the review of scientific publications, a conclusion was made about the reliability of the results obtained by passive seismic methods, which is confirmed by other independent geophysical research methods. Passive seismic methods demonstrate high efficiency when working in hard-to-reach areas, such as the Arctic zone, since they do not require long-term installation of an observation network, and when using spectral ratio methods, they do not require a large number of seismic stations. They are especially useful when studying hard to extract resources characterized by a complex structure of the upper part of the section (the first meters), since they allow for the rapid study of the upper part of the section for depths from the first meters to tens of kilometers during reconnaissance work without significant financial and labor costs. From an environmental point of view, passive seismic methods are the most gentle, as they are non-invasive and non-destructive.

The article presents the results of numerical modeling and inversion of Lateral Logging (LL) data for determining the geoelectrical parameters of oil-and-gas-saturated reservoirs in the northern fields of Western Siberia. The research is based on the analysis of synthetic LL signals calculated for a typical model of the Achimov deposits of the Yamburg field, which are characterized by small reservoir thickness. The influence of changes in parameters such as the formation resistivity, the invaded zone thickness, and depth shift on the LL signals is considered. An assessment of the accuracy of reservoir parameter recovery using two-dimensional numerical inversion was carried out, areas of equivalence were identified, and recommendations for error minimization are proposed. The results showed that the greatest sensitivity of the LL signals is observed to changes in the formation resistivity and the invaded zone thickness, with the error in determining the formation resistivity being up to 12%.

Valovayam and Tymlat adakites were formed during subduction of the Miocene oceanic lithosphere of the Komandorsky Basin beneath the North Kamchatka followed by the interaction with mantle wedge peridotites. Post-collisional adakitic dacites from the Bakening paleo-volcano (Central Kamchatka) are related to the destruction and melting of the Mesozoic Kronotsky microplate paleo-slab due to the influence of hot sub-slab asthenospheric mantle after the collision of the Kronotsky island arc. Minerals and volcanic glass in Kamchatka adakites contain predominant Cu-Ag-Au alloys and silver chloride microinclusions along with various chalcophile sulfides, native metals, alloys, oxides and carbonate hydroxides. Microinclusion assemblages in adakites are broadly comparable to the ore mineral associations in epithermal and porphyry deposits from the Russian Far East. Kamchatka adakites display elevated silver and gold contents in comparison with back-arc basin and volcanic arc lavas, which could be sourced from the metamorphosed oceanic crust and metalliferous pelagic sediments in the subducted slab. We conclude that adakites associated with subduction of the young oceanic lithosphere (North Kamchatka) and the old lithospheric slab tear and break-off (Central Kamchatka) can be magmatic precursors for the copper-gold-silver mineralization in the Kamchatka region. We also propose that adakite-related metallogenic processes may occur in the other convergent plate margin settings, for example, in the flat slab subduction environments.

Composite silicon (Si) layers containing a synthesized narrow-bandgap indium arsenide (InAs) phase are of interest from the viewpoint of extending the optical absorption region and photoresponse of Si to the near and mid-IR region (λ = 1-3.5 μm). In this work, we investigate single-crystal Si layers subjected to sequential implantation with In⁺ and As⁺ ions followed by thermal annealing in a furnace (solid-phase crystallization) or pulsed nanosecond annealing with a C⁺/H⁺ ion beam (liquid-phase crystallization). By means of scanning electron microscopy, secondary ion-mass spectrometry, x-ray diffraction, optical infrared spectroscopy, and photoconductivity methods, the structural, optical, and photoelectric properties of the composite layers are studied. It is shown that pulsed annealing leads to deep diffusion of As atoms into Si to 1 μm with the formation of a solid solution Si:As, and the In impurity is pushed to the surface. Thermal annealing leads to a slight redistribution of impurities and to the formation of secondary phases of InAs and In₂O₃. In both cases, a high electron concentration (~ 2 × 10²⁰ cm^-3) is achieved, and an intense absorption band with a maximum at 3.6 μm is detected. The photoresponse spectra of the mesa diodes at 300 K show a photosensitivity region of 0.5-1.2 μm, comparable with a typical Si photodiode. No photoresponse was detected in the region of 1.2-2.4 μm.

The method of THz radiation modulation based on the semiconductor-metal phase transition in vanadium dioxide (VO₂) is explored. Thermal heating of the VO₂ film on the silicon substrate above the metallic state temperature results in ~80% reduction of THz radiation transmission. For two-electrode VO₂ film structures with a millimeter-sized interelectrode gap, heating the film by electric current leads to ~42% transmission reduction only. At the same time, due to heating of the VO₂ film substrate, a slow (seconds-running) cooling process and the reverse transition of the film to the semiconductor state occur. To increase the modulation frequency up to hundreds of kHz, it is proposed to create a structured system of separated micron-sized VO₂-elements instead of a continuous film, which allows for much faster cooling of such elements confirmed experimentally.

The article presents the results of observations for peculiarities in natural revegetation of opencast spoil tips in the arid zones of the Republic of Khakassia. Research into the structure and productivity of pioneer plant communities was conducted for five years on various elements of mesorelief of 10-year-old opencast spoil tips of Chernogorsky Coal Mine. The research shows that primary successions have a herbaceous type of vegetation. 24 species of vascular plants are present, 87 % of them are native. On dump slopes of different aspects dominating species are forbs ( Salsola collina , Sonchus arvensis , Teloxys aristata , Erysimum cheiranthoides etc.) or Poaceae ( Calamagrostis epigeios and Hordeum jubatum ). The vertical structure exibits a near-surface type of distribution; the herbage height is lower than in zonal communities. The productivity of pioneer communities (maximal values 0.7 ± 1.6 t/ha are observed on the plateau) is lower than that of aboriginal bunch grass steppes. The above-ground phytomass predominates over the under-ground phytomass in all parts of the study site. The plant communities after 10 years of revegetation remain in an initial stage of restoration and differ in the composition and structure from the zonal communities.

The analysis of the ontogenetic composition and demographic parameters of two cenopopulations (CP) of Myricaria bracteata Royle in the bed of the rivers in Republic of Kazakhstan is carried out. The studied coenopopulations of M. bracteata reflect the influence of abiotic and biotic factors on the process of population development during overgrowth of the winding river banks. It is established that the ontogenetic structure and density of individuals depends on the degree of formation of phytocenosis and abiotic factors, as well as on anthropogenic impact. Depending on floodplain width, free space and phytocoenotic environment, the ontogenetic spectrum of CP changes from left-sided incomplete to right-sided incomplete. The type and stability of CP changes in the series: unstable invasive (in a narrow floodplain) successive transitional young normal mature normal stable (in a wide floodplain).

The article presents information on the current state of populations and abundance of the endemic species of the Eastern Caucasus flora Rhaponticoides razdorskyi (Karjagin ex Sosn.) M.V. Agab. et Greuter (Asteraceae). The altitudinal limits of the species distribution are from 200 to 600 m above sea level. The area of populations known in Russia ranges from 0.2 ha to 300.0 ha, the number of individuals per 100 m² is from 43 to 225. It was found that Rh. razdorskyi prefers slopes of southern and adjacent exposures with sparse vegetation on rocky soils. The main type of vegetation in which the species is found are mountain steppe communities with a predominance of cereals. According to the IUCN criteria, the conservation status of the species is defined as EN B2ab(iii).