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The results of a study of liquid photochemical metal-assisted etching of a series of samples of n-type Ga-polar GaN layers grown by molecular-beam epitaxy with nitrogen plasma activation are presented. Under the chosen conditions of the etching process, it is shown that the etching rate depends mainly on the structural properties of the GaN layers, which manifest themselves in the surface morphology, which can be quantitatively characterized by the multifractal parameters Δq (the degree of ordering and symmetry breaking of the structure under study) and Dq (the Rényi dimension, which depends on the thermodynamic formation conditions). A correlation between the values of the multifractal parameters Δq and Dq of the surface structure and the etching rate of Ga-polar GaN layers is established.

Background. Facial zoning based on seismic data is an important task of dynamic analysis. There are numerous approaches of solving this problem using various algorithms. The most common method is clustering by reflection shape. This approach belongs to unsupervised learning algorithms, due to the mapping of seismic facies is based on the internal data structure and the key feature is the change in the wave packet within the target interval. The disadvantage of this method is requirement of further tying clustering results and geological information. Another way of directed solution of this problem is the use of supervised learning algorithms. This category includes various classification methods that relate to the category of machine learning. In comparison to traditional approaches of seismic facial analysis, this method accounts geological information at the computation stage. Aim. This paper considers the results of a research carried out with the study of the facies structure of the Tyumen formation at a group of fields in the Khanty-Mansiysk Autonomous Region. The Tyumen formation is characterized by the predominance of channel facies associated with the development of complex river systems, which are clearly observed in the dynamic characteristics of the wave field. A complicating factor in the study of these deposits is the rather low coverage of well data, which makes difficult the geological interpretation of the results obtained. Materials and methods. The authors used the Random Forest classification method to deal with the assigned task. The application of the method is considered on the cluster consisting of three seismic surveys obtained at different times. For training, expert marking by area was used based on the distribution of amplitudes along the reflecting horizon. Results. As a result of the research, a probabilistic assessment of the distribution of channel facies was obtained, that is related to the perspective of this type of deposits in the study area. Thus, the authors have developed a methodology that gives an opportunity to obtain an estimate of the probability of the presence of a certain facies using seismic data. Conclusions. The performed study shows the possibility of using the Random Forest classification method to solve the problem of facial zoning.

Palladium mineralization was registered in the Kola superdeep borehole (SG-3) for the first time in samples from deep horizons (in the fault zone at ~10 km). A proper palladium mineral (merenskyite) with the formula Pd1.00(Te1.21Bi0.79)2.00 was detected using the analytical electron microscopy and EBSD methods. The unusually high content of bismuth in the discovered merenskyite crystal most likely indicates the lower temperatures of its formation from a bismuth-rich fluid. This is supported by numerous finds of associated bismuth minerals (native and intermetallic minerals, sulfides, tellurides, and sulfotellurides) as well. A close geochemical association of noble and rare elements was revealed in the composition of the rich and diverse ore mineralization in the samples studied. It can be argued that a new type of mineralization was discovered for the SG-3 rocks: noble metal (Au–Ag–Pd) rare-element (Bi–Te).

The results of long-term mineralogical studies of the lunar regolith, obtained using analytical scanning and transmission electron microscopy, are presented. These studies revealed 105 mineral phases new for the Moon, 43 of which were discovered for the first time under natural conditions; an electronic link to the final table is given. An example of studying condensate glasses and native molybdenum is presented.

A high-calcium high-temperature condensate is detected in the Earth’s impact Lonar crater for the first time. Its finding confirms in practice the theoretical conclusions made earlier from the experimental results. The high-silica condensate found in the Lonar crater, which is similar to those ones in the Zhamanshin crater and in the lunar regolith, confirms the absence of a correlation between the compositions of the target and the impact condensates. The presence of high-temperature condensate glasses in ring structures may be one of the diagnostic criteria to differentiate between volcanogenic and impact formations.

Individual fluid inclusions in quartz from ore veins of the Askold gold deposit, which was previously attributed to the epithermal type, are studied for the first time. It is established that gold mineralization of Askold Island derived from ore-forming fluids of carbon dioxide–water–salt composition, with a salt concentration of 2.8–4.1 wt % NaCl equiv and a high carbon dioxide concentration, at temperatures of 280–324°C and pressures of 1240–2170 bar. The tectonic control of gold mineralization, the presence of tin and bismuth minerals in the ores, the high fineness of gold, and the characteristics of the mineral-forming fluids (primarily high pressures) indicate that the Askold deposit can be attributed to the type of gold deposits associated with granitoid intrusions.

Experimental data on impact vaporization of serpentinite are presented. The experiment was carried out using a two-stage light gas gun with an impact velocity ∼6 km/s. Copper with a mass up to 0.5 g was used as the projectile. Impact-generated vapor in the form of a condensate film was analyzed using a JSM-5610 scanning electron microscope. The analysis showed that the Mg/Si ratio in the condensate decreased sharply (by ∼1.8 times) compared to the initial ratio in the serpentinite target. Thus, it is shown that the evaporation of the impact melt of the silicate target is selective: the vapor is enriched with relatively volatile SiO2, leaving a relatively nonvolatile MgO in the residual melt.

For the first time, high-purity native cobalt was detected in two preparations from a lunar regolith sample delivered by the Luna 24 automatic station. Presumably, it was formed during the condensation of a substance from an impact gas-plasma cloud. Previously, native cobalt of similar purity was observed only in products of low-temperature hydrothermal alteration of hyperbasites.

A 3-µm particle of HgS is found by electron microscopy techniques in studying the lunar regolith samples delivered by Apollo 17. It might have been preserved due to a thin cover of highly siliceous glass, having protective functions. This particle was likely formed from a gaseous phase by the condensation of Hg and S vapors.

The effect of the inversion of polarity in gallium nitride layers from the N-polar GaN layer to the Ga-polar GaN layer was discovered during the sequential growth of GaN films on hybrid SiC/Si(111) substrates by nitrogen plasma-assisted molecular beam epitaxy and chloride–hydride vapor phase epitaxy. A new method has been developed for the formation of crack-free Ga-polar GaN/AlN heterostructures on hybrid SiC/Si(111) substrates. The method includes two stages of growing gallium nitride layers. At the first stage, the transient N-polar GaN layer is grown on the SiC/Si(111) surface by nitrogen plasma-assisted molecular beam epitaxy. At the second stage, two layers are grown on the obtained N-polar GaN layer by chloride–hydride vapor phase epitaxy, namely, the AlN layer and then the GaN layer, which at this stage grows in the Ga-polar orientation. Etching in a KOH solution affects only the N-polar GaN transition layer and leads to its complete removal. This procedure separates the main Ga-polar GaN layer from the SiC/Si(111) substrate completely. The method enables one to grow crack-free and elastically unstressed thick GaN layers and transfer them to substrates of other materials.

The results of studies of photochemical etching processes, which were carried out without applying external voltage, for structures with Ga- and N-polar GaN layers synthesized by molecular-beam epitaxy with the plasma activation of nitrogen are reported. It is shown that the etching rates of layers with different polarities are markedly different. At the same time, the use of gold-based masks instead of titanium-based ones for the etching of GaN layers also provides a means for increasing the rate of layer etching.

The results obtained in a study of the synthesis of n+-GaN layers by plasma-assisted molecular-beam epitaxy on GaN/c-Al2O3 templates are reported. In particular, a method is developed for the pre-epitaxial cleaning of the GaN surfaces of templates to remove foreign atoms. It is shown that, to form GaN layers of comparatively good quality, including those doped with silicon up to ~4.6 × 1019 cm–3, GaN template surfaces should be pre-epitaxially cleaned in a flow of activated nitrogen particles, with the substrate temperature increased from TS = 400 to 600°C and the substrate surface subsequently exposed to a flow of activated nitrogen at a fixed value of TS = 600°C for 1 h. After that the substrate temperature should be raised to TS = 700°C and the GaN surface finally cleaned by means of a procedure for gallium deposition/desorption.

Based of study of the morphological features of a coal seam in a mine of the Eastern Donbas, the mineral and coal elements of the object studied were identified as a single sedimentary association of a pseudo-washout nature. Specific criteria for attributing coal-bearing structures to epigenetic or syngenetic washouts of a coal seam were elaborated.

Based on study of the morphological features of a coal seam in a mine of the Eastern Donbas, the mineral and coal elements of the object studied were identified as a single sedimentary association of a pseudo-washout nature. Specific criteria for attributing coal-bearing structures to epigenetic or syngenetic washouts of a coal seam were elaborated.

During studying samples of lunar regolith from samples of the AS “Luna-24” using the methods of Raman spectroscopy, the presence of three structural modifications of carbon was established: amorphous sp2 carbon, shungite-like carbon and turbostratic graphite. At the same time, no signs of hydrocarbons or other organic compounds were found, what excludes contamination of the sample at the preparation stage and the effect of the adhesive layer of the scotch on which the regolith fragments under study were mounted, and also contamination of the sample by the exhaust of hydrazine landing engines of the descent capsule of the AS “Luna-24”.

The Raman spectroscopic studies of the lunar regolith from the samples of the Luna 24 automatic station resulted in recognition of the occurrence of three structural modifications of carbon: amorphous sp2-carbon, schungite-like carbon, and turbostratic graphite.

A modern air separation plant control system must solve a host of problems, including variation in conditions of plant operation with full guarantee of its automatic flow. The procedure of gearing the plant from one operation mode to another is based on gradual change of control action and collection of desired products without impairment of their quality below the allowable level. To accomplish this task, it is essential to determine the values of the key process parameters for various air separation plant operation conditions and the maximally allowable control action variation rate. Based on the investigation results and comparative analysis of the values of the key process parameters of optimized static-state regimes in UniSim Design environment and actual indicators with a real plant, we found insignificant deviation of the calculated parameters from the actual values during the plant operation. It was concluded that the results of air separation process modeling in UniSim Design environment or the magnitudes of control actions derived by equations of material and heat balances of the plant can be used, in a first approximation, in plant operation mode change algorithm.

The paper presents pioneering data on the comparative study of impact glasses from the Zhamanshin crater and lunar regolith (delivered by the Luna 16, 20, and 24 probes). The data were acquired using analytical techniques of ultrahigh spatial resolution. Many of the melt and condensate impact glasses, both terrestrial and lunar, are similar in inner structure and composition, which were controlled primarily by the physics of the impacts and similar compositions of the targets.

The data on the underworking of water objects and piezometric surveys have allowed scientists to reveal a correlation between hydrodynamic conditions in groundwaters and the stressed and strained state of rock masses at the sites of underground mining of coal and oil-shale deposits. The hydraulic fracturing of the downward filtration current within the layers of clay rocks and upon their contact with sand- and limestone layers was found, along with a discontinuous distribution of hydrostatic pressure in the section of the water-conducting subsidence cracks resulting in groundwater accumulation on clay layers.

The close intergrowth of two native alloys of the compositions Ni0.59Cu0.24Al0.15Fe0.01Mn0.01 and Pd0.55Pt0.36Rh0.09 with a size of 10 μm has been discovered in the regolith from the Mare Crisium. A conclusion on its exhalative origin is made.

Two cases of mineral associations from the samples of regolith delivered by AS Luna 20 and AS Luna 24, which indicate possible hydrothermal alteration of primary lunar rocks, are considered. The probability of hydrothermal processes on the Moon means a drastic change in the firm views of the processes of the formation of lunar mineral.

In this work, the AlN/Si(111) epitaxial structures grown consistently by plasma assisted molecular beam epitaxy (PA MBE) and hydride vapour phase epitaxy (HVPE) methods were studied. The PA MBE AlN buffer layers were synthesized via coalescence overgrowth of self-catalyzed AlN nanocolumns on Si(111) substrates and were used as templates for further HVPE growth of thick AlN layer. It was shown that described approaches can be used to obtain AlN layers with sufficiently smooth morphology. It was found that HVPE AlN inherited crystallographic polarity of the AlN layer grown by PA MBE. It was demonstrated that the etching of such AlN/Si(111) epitaxial structures results in partial separation of the AlN epilayers from the Si(111) substrate and allows to form suspended structures. Moreover, the avoidance of surface damage and backside overetching was achieved by use thin Cr film as surface protective coating and by increasing the layer thickness accordingly.

Using high-resolution analytical electron microscopy, heterogeneous fragments of cosmogenic substances, such as nickelphosphide Ni3P and the unnamed intermetallide ZnAl2, are detected for the first time for a large meteorite crater, the Zhamanshin circular structure. Due to the impossibility of simultaneous finding these phases in the same meteorite, an assumption is made on the cometary nature of the impactor of the Zhamanshin crater.

Fragments of heterogeneous cosmonegic substance (nickelphosphide Ni3P and ZnAl2) were found using high resolution analytical electron microscopic techniques, for the first time in samples from a large meteorite crater: the Zhamanshin astrobleme in Kazakstan. Inasmuch as such fragments cannot simultaneously occur in meteorite of any one type, we suggest that the impactor of the Zhamanshin crater was of comet nature.

In Russia, highly radioactive liquid wastes from recycling of spent fuel of nuclear reactors are solidified into Na–Al–P glass for underground storage. The properties of the matrix including the radionuclide fixation will change with time due to crystallization. This is supported by the results of study of the interaction between glassy matrices, products of their crystallization, and water. The concentration of Cs in a solution at the contact of a recrystallized sample increased by three orders of magnitude in comparison with an experiment with glass. This difference is nearly one order of magnitude for Sr, Ce, and Nd (simulators of actinides) and U due to their incorporation into phases with low solubility in water. Based on data on the compositional change of solutions after passing through filters of various diameters, it is concluded that Cs occurs in the dissolved state in runs with a glass and recrystallized matrix. At the same time, Sr, lanthanides, and U occur in the dissolved state and in the composition of colloids in runs with glass, and mostly in colloid particles after contact with the recrystallized sample. These results should be regarded for substantiation of safety for geological waste storage.

Based on mining works near water objects, a model of water permeability in an underworked site of a coalfield under the conditions of failure roof control is given. The secondary water permeability index varies in the section as a sawtooth function and depends on the strain intensity and lithology of rock beds. The coefficient of permeability reaches maximum values in intervals of split crack propagation, sandstones, limestones increasing towards the subfaces of beds, as well as towards the mined-out area in the lower part of the zone of water-conducting subsidence cracks. The coefficient of permeability in siltstone and mudstone beds normal to beds inside the upper and central parts of zones of water-conducting subsidence cracks is at a level of 0.003 m/day.

Two different approaches for the etching of the gallium nitride epitaxial layers grown on Si(111) substrates by plasma-assisted molecular beam epitaxy have been elaborated. It is demonstrated that anisotropic etch profiles can be achieved by both photoenhanced wet chemical etching and reactive plasma-chemical etching methods. Moreover, it is shown, that the photoenhanced wet chemical etching allows to remove GaN layer without damaging silicon substrate.

The paper considers a very important problem for modern world - the energy consumption and energy saving. Nowadays households consume more than a quarter of global energy consumption (29%), which means that this sector has great savings potential. However, this potential for savings can only benefit upon development of proper structural policy measures and laws and implementation of appropriate energy-saving measures. This requires information on the future trends of energy demand and on the factors influencing this demand and the actual energy consumption. The main challenge for researchers presents the fact that energy consumption in the regional aspect is extremely uneven, structurally heterogeneous, which assumes the different measures for the energy saving in each region of the country. Besides, we were unable to find publications describe the contribution of various factors to the dynamics of the energy consumption of the regional economy at the municipal level. Hence, the paper analyzes stream-lined trends in the energy consumption in households of Germany which is one of the world leaders in these issues. So the paper highlights some factors as well as some trends affecting the energy consumption in households in the Perm region.

The GaN/Si(111) epitaxial structures were synthesized by coalescence overgrowth of GaN nanocolumns using the plasma-assisted molecular beam epitaxy (PA-MBE) technique. Such epitaxial structures can be used as a buffer layer for obtaining high quality GaN epilayers. Structural, electrical and chemical properties of these samples were studied. It was demonstrated that KOH etching of the grown GaN/Si(111) samples results in the separation of the GaN epilayer from the substrate.

Condensate glasses of two types were found during the SEM and TEM investigation of zhamanshinite samples within volumetrically dominant melt glass: silica-rich glasses similar to irghizite-type condensates and moderately silicic sodium-rich glasses deposited in voids in zhamanshinites. The latter are characterized by globular morphology, high contents of volatile components, and presence of inclusions a few hundred nanometers in size. The differences of the zhamanshinite-type condensate glasses from irghizitetype condensates are related to their slower cooling and closeness of the pore space system. The results of the investigation of melt glasses of various color groups from the same samples are presented for comparison. The glasses of each group appeared to be homogeneous at the SEM level, but inhomogeneous at the TEM scale.

The structural state was determined for zero-valence molybdenum in the lunar regolith. The body- and face-centered molybdenum forms (BCC and FCC, respectively) were identified. Disruption of the structure down to complete amorphization was noted. This might be caused by the long-term influence of the solar wind.

The interaction of aluminophosphate glass with water at 95°C for 35 days results in glass heterogenization and in the appearance of a gel layer and various phases. The leaching rate of elements is low owing to the formation of a protective layer on the glass surface. It is shown that over 80% of uranium leached from the glass matrix occurs as colloids below 450 nm in size characterized by high migration ability in the geological environment. To determine the composition of these colloids is a primary task for further studies. Water vapor is a crystallization factor for glasses. The conditions as such may appear even at early stages of glass storage because of the failure of seals on containers of high-level radioactive wastes. The examination of water resistance of crystallized matrices and determination of the fraction of radionuclide in colloids are also subjects for further studies.

Particles of tantalo–niobate of the ferrotantalite-manganotantalite series are discovered for the first time in two lunar regolith fragments delivered by the Apollo-17 mission. Allochtonous and autochtonous mineralization that accompanies tantalo–niobate in the regolith is described. An attempt is made to explain the formation of tantalite in anorthosites of the continental region of the Moon.

The dependence of the crystallographic polarity of GaN epitaxial layers produced by nitrogen plasma-enhanced molecular-beam epitaxy on Si(111) substrates on the nitridation parameters and initial growth conditions has been studied. A rapid procedure for determining the polarity of GaN epitaxial layers was developed. It was found experimentally that the nitridation parameters of the silicon substrate have no effect on the polarity of a GaN layer. It was shown that the substrate temperature in the stage of nucleation of a GaN epitaxial layer is one of the factors determining its polarity.

An approach to precision calibration of the silicon doping level in gallium arsenide epitaxial layers is discussed that is based on studying the dependence of the carrier density in the test GaAs layer on the silicon- source temperature using the Hall-effect and CV profiling techniques. The parameters are measured by standard or certified measuring techniques and approved measuring instruments. It is demonstrated that the use of CV profiling for controlling the carrier density in the test GaAs layer at the thorough optimization of the measuring procedure ensures the highest accuracy and reliability of doping level calibration in the epitaxial layers with a relative error of no larger than 2.5%.