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This paper explores the application of conceptual hydrological models in optimizing the operation of hydroelectric power plants (HPPs) in steppe regions, a crucial aspect of promoting low-carbon energy solutions. The study aims to identify the most suitable conceptual hydrological model for predicting reservoir inflows from multiple catchments in a steppe region, where spring runoff dominates the annual water volume and requires careful consideration of snowfall. Two well-known conceptual models, HBV and GR6J-CemaNeige, which incorporate snow-melting processes, were evaluated. The research also investigated the best approach to preprocessing historical data to enhance model accuracy. Furthermore, the study emphasizes the importance of accurately defining low-water periods to ensure reliable HPP operation through more accurate inflow forecasting. A hypothesis was proposed to explore the relationship between atmospheric circulation and the definition of low-water periods; however, the findings did not support this hypothesis. Overall, the results suggest that combining the conceptual models under consideration can lead to more accurate forecasts, underscoring the need for integrated approaches in managing HPP reservoirs and promoting sustainable energy production. [ABSTRACT FROM AUTHOR]

Under a water deficit, the protective proteins known as dehydrins (DHNs) prevent nonspecific interactions in protein and membrane structures and their damage, in addition to playing an antioxidant role. The DHNs of a widespread xerophytic species Scots pine (Pinus sylvestris L.) have been poorly studied, and their role in resistance to water deficits has not been revealed. In this paper, we have expanded the list of DHNs that accumulate in the cells of Scots pine under the conditions of water deficits and revealed their relationship with the effects of water deficits. In this investigation, callus cultures of branches and buds of Scots pine were used. A weak water deficit was created by adding polyethylene glycol to the culture medium. Under the conditions of a water deficit, the activity of catalase and peroxidase enzymes increased in the callus cultures. A moderate decrease in the total water content was correlated with a decrease in the growth rate of the callus cultures, as well as with an increase in the activity of lipid peroxidation. The accumulation of Mr 72, 38, and 27 kDa DHNs occurred in the callus cultures of buds, and the accumulation of Mr 72 and 27 kDa DHNs positively correlated with the lipid peroxidation activity. An increase in the content of DHNs was observed in cultures that differed in origin, growth indicators, and biochemical parameters, indicating the universality of this reaction. Thus, previously undescribed DHNs were identified, the accumulation of which is caused by water deficiency and is associated with manifestations of oxidative stress in the kidney cells of Scots pine. [ABSTRACT FROM AUTHOR]

In this paper, a methodology for experimental investigation of chemical and thermal structure of weakly stretched counterflow flames under terrestrial conditions is proposed. The non-premixed counterflow flames are stabilized in a narrow channel between quartz plates, and the flame gases are sampled by a microprobe inserted via a thin slit in one of the quartz plates. The gas samples are then analyzed by mass spectrometry. The results of the measurements of mole fraction profiles of the main components of methane-air non-premixed flames, namely, CH4, O2, H2O, CO2, and CO, are presented. The temperature profiles are also reconstructed using the measurement data for the gas composition. The experimental profiles are compared to the results of the 3D numerical simulations undertaken within the global reaction mechanisms (one- and four-step) and a detailed reaction mechanism (San-Diego). The results of this work clearly show that the thermal and chemical structures of the counterflow flame in the planar channel are essentially non-one-dimensional, and 3D-calculations are necessary to correctly predict the flame behavior in this configuration. The methodology demonstrated in the current work can be successfully employed for the investigation of the low stretched counterflow flames of various hydrocarbon fuels and fuel blends. This will allow verifying and developing the reaction kinetic models capable of quantitative prediction of weakly stretched flame behavior in confined conditions. [ABSTRACT FROM AUTHOR]

This paper presents a study of the flammability and thermal decomposition products of glass fiber-reinforced epoxy resin (GFRER) with the addition of cardanol-based phosphorus-containing benzoxazine monomer (CBz) and graphene and their combinations in different proportions (up to 20 wt.%). The addition of CBz alone or in combination with graphene resulted in an increase in the limiting oxygen index (LOI) and self-extinguishing in the UL-94 HB test. The flame-retardant samples had better tensile mechanical properties than the sample without additives. The differential mass-spectrometric thermal analysis (DMSTA) of the thermal decomposition products of GFRER without additives and with the addition of CBz and graphene was carried out. CBz addition promoted the thermal decomposition of high-molecular-weight products of epoxy resin decomposition in the condensed phase and at the same time decreased the time of release of low-molecular-weight thermal decomposition products into the gas phase. Graphene addition resulted in an increase in the relative intensities of high-molecular-mass peaks compared to GFRER without additives. [ABSTRACT FROM AUTHOR]

The influence of the forced convection rate on the chemical structure of a polymethyl methacrylate (PMMA) flame in an oxidizer flow under microgravity conditions was studied using numerical modeling. Gas flow around a solid sphere was simulated using the full Navier–Stokes equations for a multicomponent mixture. A multistep chemical kinetic mechanism was considered in the gas phase. The heat transfer and radiation in both the condensed and gas phases were considered in the modeling. On the PMMA surface, the pyrolysis reaction leading to the transformation of fuel from the condensed phase to the gas phase is specified. The forced convection speed varied in the range from 3 to 20 cm/s. Analysis of CO2 concentration fields near the burning surface under microgravity conditions showed that the maximum CO2 concentration is observed in the downstream zone. The width of the flame zone and its chemical structure depend on the intensity of forced convection. The width of the flame against the flow decreases, and the maximum CO concentration increases as the forced convection rate increases. Analysis of the rates of fuel consumption reactions showed that at a low convection speed (vst=3 cm/s), the reaction with the H radical, which has the highest diffusion coefficient, plays a crucial role in MMA oxidation. [ABSTRACT FROM AUTHOR]

It is shown that the differences water-soluble and water-insoluble fractions of plant leaf biomass, as well as phloem, are evolutionarily determined. They are associated with metabolic reactions during assimilation and photorespiration and do not depend on the illumination mode or on the spectral ranges of photosynthetic active radiation (PAR) used in illumination. The above isotopic shifts are the cause of isotopic differences in assimilatory and photorespiratory carbon stocks that feed various metabolic processes. Due to the strict temporal and spatial organization of metabolism, carbon fluxes from the funds retain isotopic differences without complete mixing. The differences in the isotopic composition of carbon of the water-soluble fraction of the biomass and carbon of phloem juice from carbon of the water-insoluble fraction are small (1–3‰), but they are quite stable and easily fixed. The carbon of the water-soluble fraction is very close in isotopic composition to the carbon of the phloem and is noticeably enriched in isotope 13C relative to the water-insoluble fraction, which makes it possible to use it as a marker in the study of assimilate transport in plants, especially during budding and fruiting. It is shown that the reason for the enrichment of autotrophic organs and tissues with the isotope 12C relative to carbon of heterotrophic parts of the plant is the result of predominant participation in their formation of an isotopically light assimilation fund, whereas an isotopically heavy photorespiratory fund takes part in the formation of heterotrophic organs. It is shown that the manifestation of the formation of two isotopically different funds is the discovered relationship of the carbon isotope composition of leaves with their age. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) are promising nanostructures in the field of photonics owing to the ease of fabrication, tunable and efficient emission. Gallium phosphide (GaP) nanowires are known for high surface area, optical density, waveguiding, resonant optical properties but lacking the luminescence due to the indirect bandgap. Here, hybrid photonic structures – GaP nanowires decorated with the CDs are fabricated and studied. Feasible drop‐casting deposition technique allows fabrication of dense vertical structures exhibiting efficient photoluminescence. Deposition of the CDs over the nanowires does not affect their luminescent properties demonstrating tolerance of the approach toward the surface aggregation. Tuning of the emission spectrum is obtained via variation of the excitation wavelength and CDs' synthesis protocol. The structures emitting throughout the visible range are obtained. Analysis of the photoluminescence of an individual structure demonstrates the most intense and fast recombination processes at the ends of a nanowire. It is shown that the luminescence of the CDs' covering a nanowire acting as a Fabry–Perot cavity is enhanced up to a factor of 3 governed by the Purcell effect. The obtained results unveil a path for fabrication of novel photonic devices via decoration of optically dense nanowires with CDs for enhanced and directed broadband emission. [ABSTRACT FROM AUTHOR]

The Acorus calamus group, or sweet flag, includes important medicinal plants and is classified into three species: A. americanus (diploid), A. verus (tetraploid), and A. calamus (sterile triploid of hybrid origin). Members of the group are famous as components of traditional Indian medicine, and early researchers suggested the origin of the sweet flag in tropical Asia. Subsequent research led to an idea of the origin of the triploid A. calamus in the Amur River basin in temperate Asia, because this was the only region where both diploids and tetraploids were known to co-occur and be capable of sexual reproduction. Contrary to this hypothesis, triploids are currently very rare in the Amur basin. Here, we provide the first evidence that all three species occur in Kazakhstan. The new records extend earlier data on the range of A. verus for c. 1800 km. Along the valley of the Irtysh River in Kazakhstan and the adjacent Omsk Oblast of Russia, A. verus is recorded in the south, A. americanus in the north, and A. calamus is common in between. We propose the Irtysh River valley as another candidate for a cradle of the triploid species A. calamus. It is possible that the range of at least one parent species (A. americanus) has contracted through competition with its triploid derivative species, for which the Irtysh River floods provide a tool for downstream range expansion. We refine our earlier data and show that the two parent species have non-overlapping ranges of variation in a quantitative metric of leaf aerenchyma structure. [ABSTRACT FROM AUTHOR]

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The paper presents the results of research into the influence of the titanium foil thickness on the impact response of metal-ceramic ZrO2/Ti/ZrO2/Ti composites consisting of nonrigidly joined plane-parallel layers. The difference is shown between the deformation behavior of the metal foils in composites with foil thicknesses of 100, 200, and 500 μm. It is found that an increase in the thickness of reinforcing metal layers leads to a higher structure dispersion in the deformation localization zone. The deformation and fracture features of each layer of the composites are studied in detail. A comparative analysis is made of the structural characteristics of materials before and after impact loading. [ABSTRACT FROM AUTHOR]

A comprehensive study was performed on the supramolecular ordering and optical properties of thin nanostructured glycerohydrogel sol-gel plates based on chitosan L- and D-aspartate and their individual components in the X-ray, UV, visible, and IR ranges. Our comparative analysis of chiroptical characteristics, optical collimated transmittance, the average cosine of the scattering angle, microrelief and surface asymmetry, and the level of structuring shows a significant influence of the wavelength range of electromagnetic radiation and the enantiomeric form of aspartic acid on the functional characteristics of the sol-gel materials. At the macrolevel of the supramolecular organization, a complex topography of the surface layer and a dense amorphous–crystalline ordering of polymeric substances were revealed, while at the nanolevel, there were two forms of voluminous scattering domains: nanospheres with diameters of 60–120 nm (L-) and 45–55 nm (D-), anisometric particles of lengths within ~100–160 (L-) and ~85–125 nm (D-), and widths within ~10–20 (L-) and ~20–30 nm (D-). The effect of optical clearing on glass coated with a thin layer of chitosan L-(D-)aspartate in the near-UV region was discovered (observed for the first time for chitosan-based materials). The resulting nanocomposite shape-stable glycerohydrogels seem promising for sensorics and photonics. [ABSTRACT FROM AUTHOR]

A solvent-free method was proposed for the synthesis of hexaimidazolecobalt(II) nitrate and perchlorate complexes—[Co(C3H4N2)6](NO3)2 and [Co(C3H4N2)6](ClO4)2—by adding cobalt salts to melted imidazole. The composition, charge state of the metal, and the structure of the resulting complexes were confirmed by elemental analysis, XPS, IR spectroscopy, and XRD. The study of the thermochemical properties of the synthesized complexes showed that [Co(C3H4N2)6](NO3)2 and [Co(C3H4N2)6](ClO4)2 are thermally stable up to 150 and 170 °C, respectively. When the critical temperature of thermal decomposition is reached, oxidative two-stage gasification is observed. In this case, the organic component of the [Co(C3H4N2)6](NO3)2 complex undergoes almost complete gasification to form Co3O4 with a slight admixture of CoO, which makes it attractive as a component of gas-generation compositions, like airbags. [ABSTRACT FROM AUTHOR]

The deformation behavior of ZrO2 under compression of cylindrical and three point bending of V-notched beam-shaped samples has been investigated. The ceramics possess 50% porosity and the average pore size varying from 10 to 300 μm. It is shown that the formation of stochastic porosity and further increase in the average pore size lead to a multiple strength decrease relative to a non-porous sample. At the same time, the deformation behavior changes from elastic to pseudoplastic one reflected by the appearance of many local minima in the deformation curves and the increase in the relative ultimate strain. A plateau is found in the fracture toughness dependence on the pore size due to the increase in the main crack trajectory running mainly between the pores. In addition, the formation of multiple microcracks is found, also preventing the development of the main crack. [ABSTRACT FROM AUTHOR]

Commonly considered bispecific, Acorus is one of the most phylogenetically isolated angiosperm genera that forms the order Acorales sister to the rest of the monocots. The Acorus calamus group is widely distributed in the Holarctic regions of Eurasia and America and has strong medicinal and other practical uses since prehistoric times. Earlier studies interpreted native diploids and invasive triploids occurring in North America as two species that differed in morphology and distribution ranges. In contrast, diploids, triploids, and tetraploids occurring in Eurasia are commonly interpreted as one species because they reportedly cannot be distinguished in collections. We resolve the controversy over taxonomic concepts between Eurasia and America and provide the first detailed multidisciplinary account of Acorus in temperate Asia. We used plastid and nuclear markers, leaf anatomy, seed micromorphology, pollen stainability, flow cytometry, and direct chromosome counts. Diploids and tetraploids show stable molecular and micromorphological differences. Triploids are their sterile hybrids, with the plastid genome inherited from the diploid parent. Diploids of America and Asia tend to differ in leaf characters. Coadaptative coexistence with pollinating beetles Platamartus jakowlewi and Sibirhelus corpulentus (Kateretidae) is conserved between diploids and tetraploids and over a distance of 4700 km between Japan and Western Siberia. Diploids are self‐compatible and can set seeds in the absence of kateretid beetles. Tetraploids are self‐incompatible and/or cannot set seeds in the absence of Platamartus and Sibirhelus. Diploids (A. americanus) and tetraploids (A. verus) are two biological species; the former has two subspecies. Acorus calamus should be restricted to triploids; it apparently first evolved in temperate Asia. Diploids mostly occur in much cooler climates than triploids and tetraploids. Accessions of A. verus and A. calamus from tropical Asia are apparently derived from ancient introductions. Our data provide a new framework for the pharmacological use of Acorus. [ABSTRACT FROM AUTHOR]

In this work, NiO and NiO–SiO2 are studied using X-ray diffraction and the method of atomic-pair radial distribution. Using X-ray phase analysis, it is determined that the sizes of NiO particles have a coherent-scattering region of more than 100 nm, while the NiO–SiO2 sample has particle sizes of about 2–3 nm. However, full-profile simulation using the Rietveld method does not allow one to describe the effects observed during diffraction: asymmetry of the peaks, the appearance of an additional shoulder of peak 111 in the region of small angles; therefore, the method of atomic-pair radial distribution is used to analyze the structure. When simulating the experimental curve of the atomic-pair radial distribution, 3 different models are used: pure NiO, a mixture of NiO and Ni2SiO4, as well as a modified NiO model with Si embedded into the crystal lattice. The latter model is created based on the assumption of the incorporation of silicon into the NiO structure, as can be evidenced by the X-ray diffraction data. According to the results of simulation of the curve of the atomic-pair radial distribution, it is the latter model that provides the best description of the observed effects: a significantly increased unit-cell parameter in comparison with the sample without the addition of SiO2, as well as decreased cation–oxygen distances in the structure while the distances between cations are increased. [ABSTRACT FROM AUTHOR]

The effect of He-Ne laser radiation on the composition and content of cell membrane components, namely phospholipids (PL) and sterols, in wheat callus tissues was studied by chromato-mass spectrometry and thin-layer chromatography. It was shown that irradiation of calluses with laser light at a dose of 3.6 J/cm2 resulted in significant changes in the content of these components. Thus, the content of phosphatidylinositol increased in irradiated callus by 8 times, phosphatidylethonolamine by 2 times, and the content of phosphatidic acid decreased by 20% of the sum of PL. For sterols it was found that irradiation caused the most significant changes in the content of β-sitosterol dominant in plants (increase from 1453 ± 170 μg/g dry weight in unirradiated control to 2001 ± 111 μg/g dry weight 1 h after exposure); due to this, the total content of sterols also increased. The analysis of the obtained results suggests that PLs and sterols, primarily those for which regulatory and signaling functions are known, participate in the reaction of plant tissue to exposure to low-intensity He-Ne laser irradiation. This participation is realized as a stress (nonspecific) response to intense radiation. [ABSTRACT FROM AUTHOR]

Our knowledge of marine reptiles of the Callovian age (Middle Jurassic) is majorly based on the collections from the Oxford Clay Formation of England, which yielded a diverse marine reptile fauna of plesiosaurians, ichthyosaurians, and thalattosuchians. However, outside of Western Europe, marine reptile remains of this age are poorly known. Here, we survey marine reptiles from the Callovian stage of European Russia. The fossils collected over more than a century from 28 localities are largely represented by isolated bones and teeth, although partial skeletons are also known. In addition to the previously described rhomaleosaurid and metriorhynchids, we identify pliosaurids of the genera Liopleurodon and Simolestes; cryptoclidid plesiosaurians, including Cryptoclidus eurymerus, Muraenosaurus sp., and cf. Tricleidus, and ophthalmosaurid ichthyosaurians, including the iconic Ophthalmosaurus icenicus. These findings expand the ranges of several Callovian marine reptile taxa far to the Eastern Europe, and support the exchange of marine reptile faunas between Western and Eastern European seas in the middle to late Callovian. However, some specimens from the lower Callovian of European Russia show differences from typical representatives of the middle Callovian Oxford Clay fauna, possibly representing the earlier stages of evolution of some of these marine reptiles not yet recorded in Western Europe or elsewhere. [ABSTRACT FROM AUTHOR]

This review addresses the modeling approaches for heat transfer processes in oil-immersed transformer. Electromagnetic, thermal, and hydrodynamic thermal fields are identified as the most critical aspects in describing the state of the transformer. The paper compares the implementation complexity, calculation time, and details of the results for different approaches to creating a mathematical model, such as circuit-based models and finite element and finite volume methods. Examples of successful model implementation are provided, along with the features of oil-immersed transformer modeling. In addition, the review considers the strengths and limitations of the considered models in relation to creating a digital twin of a transformer. The review concludes that it is not feasible to create a universal model that accounts for all the features of physical processes in an oil-immersed transformer, operates in real time for a digital twin, and provides the required accuracy at the same time. The conducted research shows that joint modeling of electromagnetic and thermal processes, reducing the dimensionality of models, provides the most comprehensive solution to the problem. [ABSTRACT FROM AUTHOR]

The total and radiative heat fluxes from the flame to the burning surface of a solid fuel (polymethylmethacrylate) slab for horizontal flame spread over the fuel surface were first quantitatively measured using two water-cooled miniature (2.3 × 2.3 mm) sensors mounted inside the slab. The design of the water cooling of 2 × 2 × 0.5 mm sensors (greenTEG AG) allows their placement directly in the combustion zone. Radiative heat flux was measured by a sensor with a protective ZnSe window, and the total heat flux was measured by a similar sensor without a protective window. The conductive heat flux determined using sensors was compared with that calculated from the data of polymethylmethacrylate flame temperature measurements using thin thermocouples. The maximum radiative and total heat fluxes from the flame to the polymethylmethacrylate surface measured by the heat flux sensors were 30–35 and 70–75 kW/m2, respectively. [ABSTRACT FROM AUTHOR]

Propylene oxide (C3H6O) is an intermediate product of the oxidation of heavy hydrocarbons and can be used as an additive to conventional fuels to reduce soot emissions. New experimental data on the oxidation of C3H6O at low temperatures were obtained using an isothermal jet-stirred reactor. Experiments were carried out at temperatures of 600–1300 K and a pressure of 1 atm, and the residence time of the gas mixture in the reaction volume was 1 s. Five detailed chemical kinetic mechanisms taken from the literature were tested. The mechanism with the best predictive capability at low temperatures was determined. The mechanisms were also tested against experimental data on the structure of C3H6O flames. It has been found that there is currently no model that can correctly describe the combustion and oxidation of C3H6O at both low and high temperatures. [ABSTRACT FROM AUTHOR]

This article presents results of the comprehensive study (composition, reservoir properties, geophysical parameters, and age) of altered felsic volcanic rocks (rhyolites, dacites) associated with the Permian-Triassic intermediate structural level of the West Siberian. As a result of secondary alteration, oil and gas reservoirs can form in these volcanic rocks. Taking into account their occurrence depth (more than 2 km), they are available for study only from core and geophysical data. Based on the results of core studies, 25 petrographic varieties of felsic volcanics were established. The combination of such features as 1) structural and textural features, 2) degree of secondary alteration, and 3) peculiarities of logging curves made it possible to group these numerous petrographic varieties into six key rock types. At the same time, the distinguished rock types are characterized by different reservoir properties (porosity, permeability). All 443 samples representing various rock types are characterized by similar geochemical composition, and the U-Pb ages obtained by the zircons (254 ± 2–248.2 ± 1.3 Ma) indicate that the studied felsic volcanics belong to a single tectonic-magmatic stage at the Permian-Triassic boundary. According to seismic data, it was revealed that within the Frolov megadepression (the central part of Western Siberia), the studied volcanic rocks are distributed within grabens. In particular, the boundaries of a relatively large (70 km wide and 200 km long) graben-like Rogozhnikov-Nazym structure were adjusted, and several similar, but smaller structures were identified. A comprehensive analysis of core, log and seismic data made it possible to determine the morphology and spatial relationships of volcanic bodies composed of various types of felsic volcanic rocks, providing the basis for predicting intervals of the section with the best reservoir properties. [ABSTRACT FROM AUTHOR]

Organometallic complexes of transition metals with inorganic anions are considered as promising precursors for the synthesis of nanoscale materials used in various applications including chemical catalysis. In this work, organometallic complexes of nickel, iron, and copper with imidazole as an organic ligand and the nitrate anion as an inorganic ligand were synthesized and characterized. The kinetic parameters of thermal decomposition of the synthesized organometallic complexes were determined by low heating-rate thermogravimetric analysis and high-speed dynamic mass spectrometric thermal analysis. The main gaseous products of thermal decomposition of the complexes under high-speed heating were identified. The chemical and phase compositions of condensed combustion products of the organometallic complexes in air were studied. [ABSTRACT FROM AUTHOR]

Increasing the energy efficiency of thermal power plants operating according to the Rankine cycle is one of the priority tasks of the Russian energy sector. Despite a significant amount of scientific research, the efficiency of installations of this type still remains low. As a technological solution to increase their efficiency, the authors consider a modernized Rankine cycle in which an aqueous solution of lithium bromide is used as a working fluid, the condensation process of exhaust steam after the turbine is replaced by the process of its absorption, and the second working fluid is an absorbent. The features of the functioning of such a cycle are outlined, and the methodology for its calculation is presented. Studies have shown that the use of lithium bromide solution can reduce the steam pressure after the turbine and increase the useful heat drop as well as the degree of cycle filling. In addition, when the heat of the solution returned from the boiler is regenerated, the average temperature of the heat supply to the cycle increases, which also increases its thermal efficiency compared to the traditional circuit. The energy efficiency of the modernized cycle was analyzed and compared with the traditional Rankine cycle on water vapor. Calculations have shown that the use of a modernized cycle allows increasing thermal efficiency by an average of 1–2% compared to the traditional solution. The indicators characteristic of both steam power and absorption cycles were studied, and graphical dependences of efficiency on the main parameters were derived. The economic effect of using the modernized scheme is to reduce fuel consumption and emissions of harmful substances into the atmosphere in proportion to the reduction in fuel consumption. [ABSTRACT FROM AUTHOR]

The paper studies physical and mechanical properties of multicomponent (Zr+TiBSiNi)N coating synthesized by vacuum-arc deposition using the traditional plasma-assisted gas source "PINK" and new beam-plasma formation (BPF) system. It is shown that the coating obtained by using the BPF system, has better properties that the coating obtained by using the traditional plasma-assisted gas source. In the first case, the coating hardness is 47.8 GPA and in the second case, it is 40.9 GPa. The X-ray diffraction analysis shows that along with ZrN and TiN phases, the BPF-synthesized coating consists of the superhard and heat-resistant TiB2 phase. The X-ray diffraction analysis of the phase composition conducted for the in situ synchrotron radiation beam, shows that notable phase transformations start at temperatures higher than 750°C. [ABSTRACT FROM AUTHOR]

The paper deals with multilayer CrN/AlN coatings fabricated by the plasma-assisted vacuum-arc deposition onto a WC–8Co alloy substrate. The use of a screen for separating alternately Cr and Al flows, allows to create a multilayer coating structure with CrN and AlN nanolayers. The X-ray diffraction analysis shows that the structure of obtained coatings consists of CrN and AlN phases with the face-centered cubic crystal structure. It is found that a 5 rpm rotation speed of the turning table is the best and provides the most appropriate ratio between the thickness of CrN and AlN layers and the ratio between their phase compositions. This allows minimizing the wear rate intensity of the coatings. The in situ synchrotron X-ray diffraction analysis confirms the presence of CrN and AlN phases in the temperature range of ~1075 to 1080°C. [ABSTRACT FROM AUTHOR]

The paper deals with CrAlYN/CrAlYO multilayer coatings obtained by the plasma-assisted vacuum-arc deposition onto a WC–8Co alloy substrate. It is investigated how the layer number and thickness of 16- and 32-layer coatings with the thickness of ~240 and ~120 nm, respectively, affect the phase composition, crystal structure parameters, roughness, surface morphology, and physical and mechanical properties. The X-ray diffraction analysis shows that the obtained multilayer coatings have a multiphase structure consisting of nitride CrN and AlN and oxide Cr2O3 and AlYO3 phases. It is found that the roughness of the 32-layer CrAlYN/CrAlYO coating is almost 2 times lower than that of the 16-layer coating. It is shown that the larger number of layers and their lower thickness have a positive effect on physical and mechanical properties of the coatings. The hardness of the 32-layer coating increases by 52%. The synchrotron X-ray diffraction analysis of the 32-layer CrAlYN/CrAlYO coating shows its thermal stability up to ~1020°C during heating in air, while during heating in vacuum, its thermal stability keeps constant up to at least 1500°C. [ABSTRACT FROM AUTHOR]

Ti1 – xAlxN coatings with different Al content (x = 0.1–0.43) are grown on WC–Co substrates by dual high-power impulse magnetron sputtering in the Ar/N2 atmosphere. The coating resistance to high-temperature oxidation is determined. For this, the phase composition change is investigated by synchrotron radiation during heating in the air from room temperature to 1100°С. Mechanical properties (hardness, elastic modulus, plasticity index, and plastic deformation resistance) are determined by nanoindentation of coatings before and after heating to 1100°С. X-ray diffraction patterns demonstrate the formation of the TiO2 phase on the surface of all coatings, while the formation temperature and the phase type (brookite or rutile) depend on the Al content in the coating. All coatings are not subject to spinodal decomposition into the TiN and AlN phases after heating to 1100°С. The Ti0.57Al0.43N coating possesses the highest heat resistance; it undergoes the smallest change in the phase composition and mechanical properties after the high-temperature treatment. [ABSTRACT FROM AUTHOR]

The results of studying multilayer CrN/AlN coatings obtained by vacuum-arc plasma-assisted evaporation at different speeds of rotation of the sample holder, as a result of which the thickness of individual CrN and AlN layers is assumed to be changed, are presented. The coatings are deposited onto a substrate made of VK8 hard alloy (WC + 8% of Co). The thickness of all multilayer CrN/AlN coatings is about 3 μm. Using energy-dispersive X-ray spectroscopy, it is shown that the CrN/AlN coatings under study have almost the same elemental composition. According to the results of X-ray phase analysis, it is found that CrN/AlN coatings have a two-phase structure consisting of CrN and AlN phases with a face-centered cubic (fcc) lattice. Nanoindentation revealed that the nanohardness values of CrN/AlN coatings vary from 28 to 33 GPa within the confidence interval, i.e., practically independent of the evaporation modes. The best tribotechnical characteristics are exhibited by CrN/AlN coatings obtained at a rotation speed of 5 rpm; it is likely that under this deposition condition, the optimal thickness of the CrN and AlN layers is achieved. By X-ray phase analysis using synchrotron radiation, it is found that chromium and aluminum nitrides retain thermal stability during heating to a temperature of ~1110–1115°C in air, and at least to a temperature of 1300°C in vacuum. [ABSTRACT FROM AUTHOR]

The paper presents the results of comparative study of the mechanical properties and heat resistance of a zirconium nitride mononitride coating and a multicomponent coating obtained by sequential and simultaneous deposition of zirconium and multicomponent cathode (titanium, boron, silicon, and nickel) in a nitrogen-containing medium. Multicomponent cathode was fabricated by self-propagating high-temperature synthesis with simultaneous pressing. The coatings were deposited on the hard alloy VK8 by the vacuum-arc plasma-assisted method. Material science studies of coatings included: measuring the thickness of coatings by calo testing, evaluating the adhesion strength of a coating to a substrate by the Rockwell method and scratch testing, measuring hardness before and after high-temperature annealing in air at a temperature of 700°C for 60 min, X-ray phase analysis of coatings before and after high-temperature annealing. Multicomponent coating (Zr + Ti–B–Si–Ni)N was also investigated for heat resistance in real time by X-ray phase analysis using synchrotron radiation. The adhesive strength of the multicomponent coating (Zr + Ti–B–Si–Ni)N satisfies the generally accepted quality requirements for vacuum-arc coatings. The residual hardness of the multicomponent coating (Zr + Ti–B–Si–Ni)N after high-temperature annealing significantly and noticeably exceeds the hardness of the ZrN coating after annealing. Data of X-ray phase analysis confirm the high heat resistance of the multicomponent coating (Zr + Ti–B–Si–Ni)N, which, together with the results of mechanical tests, allows us to conclude that it is promising for practical purposes. [ABSTRACT FROM AUTHOR]

The results of studies aimed at synthesizing coatings of ceramic high-entropy alloys by the vacuum-arc plasma-assisted method with simultaneous evaporation of several cathodes are presented. The optimal regimes for deposition a nitride coating of the (NbMoCrTiAl)N composition were revealed. To determine the contribution of the ion current of each arc evaporator, the azimuthal characteristics of the ion current density of the arc evaporators and the PINK-P gas plasma generator were measured. It is shown that the formed coating had a non-equiatomic composition, and the concentration of metal atoms in the coating varied from 6.6 at % up to 13.9 at %. It was established that the coating was multilayer with a layer thickness of (23–27) nm. Layers enriched in titanium atoms, alternating with layers enriched in chromium, molybdenum, and niobium atoms, were revealed. It was suggested that one of the reasons for the observed layering of the coating in terms of elemental composition was the difference in the types of crystal lattices of those elements. X-ray phase analysis was performed using synchrotron radiation, and the results of transmission electron microscopy showed that the synthesized coating had a columnar nanocrystalline structure. The transverse size of the columns varied from 20 to 170 nm, and the longitudinal size varied from 115 to 700 nm. The average crystallite size was 2.5–6 nm. The hardness of the resulting coating was 43 GPa, the friction coefficient was 0.5, and the wear parameter (a value inversely proportional to wear resistance) was 7 × 10–6 mm3 N–1 m–1. [ABSTRACT FROM AUTHOR]

A new section Salsuginosae in the genus Potentilla is described based on morphological characteristics and ecological confinement. It contains P. laevipes and P. laevissima, two rarest endemics of the Altai Mountainous Country, known from collections only from Western Mongolia. For the representatives of the new section, for the first time, data on the genome size and chromosome numbers were revealed, information on morphology and distribution was supplemented, and a conservation status was proposed. Photos of P. laevissima in its natural habitat are provided, for the first time. Most of the studied herbarium samples were scanned and are provided in the Global Biodiversity Information Facility (GBIF.org). [ABSTRACT FROM AUTHOR]

A description of a small icing wind tunnel designed for studying the icing processes at the Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences is presented. The use of such a wind tunnel offers a possibility not only of studying the physical features of the icing process, but also of testing methods of anti-icing control, validating numerical methods used for calculating the icing processes, etc. [ABSTRACT FROM AUTHOR]

Heat and mass transfer processes and the rate of fuel oxidation are the determining parameters of combustion of non-premixed gaseous fuel–oxidizer flows and solid-fuel combustion in a gaseous oxidizer. A correct description of these processes is of both scientific and practical interest. The influence of the kinetics of chemical reactions and diffusion of fuel molecules on the thermal and chemical structure of the flame forming around a polymethyl methacrylate (PMMA) sphere in air under natural convection has been studied by numerical simulation. The three-dimensional gas flow around the solid body has been calculated using the full Navier–Stokes equations for a multicomponent mixture taking into account diffusion and heat transfer between the surface and gas, convection, and radiative heat transfer. The kinetic model represents the conjugate reactions both on the condensed material surface and in the gas phase. The formation of the gaseous fuel methyl methacrylate (MMA) on the surface is described by an effective one-step pyrolysis reaction of PMMA. The oxidation of MMA in the gas phase is described by the global reaction C5H8O2 + 6O2 5CO2 + 4H2O. It has been found that the temperature and species concentration profiles in the flame practically do not depend on the rate constant of this reaction provided that the characteristic reaction time is much less than the characteristic time of MMA diffusion. It has been shown that varying the MMA diffusion coefficient has a significant effect on the thermal and chemical structure of the flame. Increasing the MMA diffusion coefficient increases the maximum flame temperature. The results of the study show that the transport properties of compounds required to calculate their transport coefficients are among the most important parameters for accurate CFD simulation. [ABSTRACT FROM AUTHOR]

In this paper, we examine the combustion of a hydrogen microjet outflowing from a curved channel with a round micronozzle. Jet flows that are generated using rectilinear and curved channels differ in that, in the second case, Dean vortices make a noticeable contribution to the formation of the jet and its combustion. The interaction of the latter with Kelvin–Helmholtz vortices, the formation of which is typical for flows with a velocity shift, causes changes in the combustion characteristics. They include spatial distortions of the laminar flame zone near the nozzle exit, the area of turbulent combustion downstream, as well as the turbulent flame under the conditions of its separation from the nozzle exit and the cessation of laminar combustion in the initial section of the flow. The results of these studies provide the possibility to understand better the combustion features of hydrogen microjets under conditions of their hydrodynamic instability. [ABSTRACT FROM AUTHOR]

Selaginella sanguinolenta group is widely distributed from the Himalayas to Siberia and the Russian Far East, including four to nine taxa. Despite progress in recent phylogenetic studies of the S. sanguinolenta group, the problem of species delimitation in this group remains. We revise the taxonomy of the S. sanguinolenta group based on an integrative approach considering morphological, molecular, and geographical evidence. The sampling for molecular analysis based on rbcL, psbA, and 26S nrDNA sequence data involved 71 individuals, covering the geographical range of this group. A total of 21 morphological traits from 103 specimens were explored using principal component analysis and linear discriminant analysis (LDA). The LDA results indicate that the combination of ventral leaf cilium length and ventral/dorsal leaf carinate characteristics enable a success rate of more than 90% in distinguishing between S. aitchisonii (western Himalayas to northern China), S. jacquemontii (western Himalayas to southwest China), and S. sanguinolenta (Russian Far East regions to northeast China). The phylogenetic analysis results of nuclear and plastid DNA markers further disclose the clear molecular differentiation. Selaginella nummularifolia, S. rossii, and S. sajanensis are well‐defined species based on morphological and molecular evidence with narrow distribution ranges respectively. Based on molecular and morphological evidence, in combination with distribution information, we finally recognize seven species in the S. sanguinolenta group, including a new species, S. baodongii sp. nov. from the bordering regions of Russia and China in northeast Asia. [ABSTRACT FROM AUTHOR]

The structure and state of ultrafine particles of the active component in the composition of deposite single-metal- and bimetallic catalysts (Pt, Rh)/Al2O3 are studied using the X-ray method of pair distribution function analysis. It is shown that particles of metallic platinum Pt0 are formed in the Pt/Al2O3 catalyst, and particles of Pt0 and rhodium oxides are formed in the Pt–Rh/Al2O3 catalyst. The determined particle sizes are consistent with electron-microscopy data. [ABSTRACT FROM AUTHOR]

The development of alloys called high-entropy alloys, which consist of several (usually five or more) basic elements, in contrast to conventional alloys with one and rarely two basic elements, indicates the emergence of a new class of metallic materials with a unique combination of mechanical, physical, tribological, and other properties. The aim of this work is to analyze the results obtained in the study of the elemental and phase composition, and defect substructure of multilayer multielement nanostructured metal films (so-called high-entropy alloys of nonstoichiometric composition) by X-ray diffraction analysis and transmission diffraction electron microscopy. Films of high-entropy alloys are formed by depositing a metal plasma onto a substrate, which is formed as a result of the vacuum arc plasma-assisted simultaneous independent evaporation of cathodes of the following groups of metals: Nb, Mo, Cr, Ti, Al (sample 1) and Ti, Al, Cu, Zr, and Nb (sample 2). The elemental composition of the films is revealed. It is found that the obtained films are multilayer and have a nanocrystalline structure. Sample 1 is a single-phase material based on a MoNbCrTiAl solid solution with a body-centered cubic (bcc) crystal lattice with a parameter of 0.3166 nm. Sample 2 is an X-ray amorphous material. It is found that the microhardness of films 1 deposited on VK8 hard alloy turns out to be higher than that of films 2. [ABSTRACT FROM AUTHOR]

Samples of the Pr–Ce–Ni–O system with Ce content relative to Pr: 5, 25, 50 mol % were synthesized by a modified Pechini method and studied using in situ synchrotron XRD in the temperature range of 30–700–30°C first in an inert gas flow then in a synthetic air flow. The formation of a first-order Ruddlesden–Popper phase, as well as two cubic fluorite-type phases, was observed for a 5 mol % Ce : Pr sample. A sample with 25 mol % Ce : Pr comprised two fluorite phases. During heating in an inert gas flow, reversible Pr7O12-type phase formation was observed from some part of the fluorite phases. A sample with 50 mol % Ce : Pr comprised a single fluorite phase that turned out to be inhomogeneous with some close cation content distribution, which could be seen in the oxygen incorporation region upon heating in a synthetic air flow after thermocycling in an inert gas flow. It is seen under these conditions since the fluorite lattice parameter is sensitive to oxygen release (a sharp increase in the lattice parameters) and oxygen incorporation (a sharp decrease in the lattice parameters). [ABSTRACT FROM AUTHOR]

A developed vacuum-arc plasma-assisted method is applied to produce films of a high-entropy alloy from a multicomponent gas-metal plasma generated by the simultaneous independent evaporation of selected metal cathodes. New modes are revealed to allow the deposition of thin films of a high-entropy alloy, AlTiCrNbMo–N, with a nearly equiatom composition. The films are a multilayer nanocrystalline material with a body-centered cubic lattice, the parameter of which specifically depends on the concentration of elements in the alloy. The synchrotron-radiation technique demonstrates that films of the high-entropy alloy AlTiCrNbMo–N are stable when heated in air to temperatures not exceeding 620°C. [ABSTRACT FROM AUTHOR]

Using high-resolution X-ray diffraction and synchrotron radiation, as well as scanning electron microscopy, it is shown that the observed high reactivity of commercial aluminum alloys activated with the Ga–In eutectic is associated with the formation of the Al–Ga–In eutectic along the grain boundaries in the entire material volume. The loss of material activity during storage under atmospheric conditions is due to oxidation of the eutectic components. Activation with pure gallium leads to the formation of AlGax solid solution, which has low activity in the reaction with water under neutral pH. [ABSTRACT FROM AUTHOR]