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The thermochemical treatment of tungsten trioxide (WO3) nanostructured films in hydrogen sulfide to obtain tungsten disulfide (WS2) layers in the WS2/WO3 hybrid structure is studied. The temperature and treatment time influence the structural-phase state, morphology, optical properties of a WS2/WO3/FTO photocathode (on fluorinated tin oxide (FTO) substrates), and its photoelectrocatalytic activity in the hydrogen evolution reaction in acidic solution is established. The sulfidation of WO3 nanoneedle films leads to the formation of a WS2/WO3 nanocrystalline hybrid structure under optimal conditions, which provides the separation of photogenerated carriers (electrons and holes) at the interphase boundaries (heterojunctions) necessary for the efficient photoactivated hydrogen evolution reaction according to Z scheme. The calculations of thermodynamic properties of the WS2/WO3 hybrid nanocatalyst show that synergistic effect of nanophases is possible in it to increase the catalytic activity of hydrogen evolution both on the basal planes of WS2 nanoclusters and on the surface of metal oxide nanoclusters.

The influence of the chemical state of a WOy thin-film precursor on formation of WSe2 nanofilms under rapid selenization on a glassy carbon substrate at 900°C is studied. A nanolayer of amorphous molybdenum sulfide (MoSx ~ 3), which has high catalytic activity in the electrochemical reaction of hydrogen evolution, is applied onto the surface of the obtained WSe2 films by pulsed laser deposition. It is shown that the composition of the WOy thin-film precursor has a significant effect on the morphology of the WSe2 nanolayers, and this characteristic largely determines the efficiency of hydrogen evolution by the MoS3/WSe2 heterostructure upon photoactivated water splitting. The most efficient hydrogen evolution is found for the MoS3/WSe2 photocathode heterostructure containing WSe2 in the form of crystal petals of ~50 nm in thickness, with these crystals oriented perpendicular to the substrate surface. A theoretical analysis of the possible effect of synergistic interaction at the MoS3/WSe2 interface on the efficiency of hydrogen evolution is carried out. Density functional theory calculations have shown that MoS3 clusters can increase the efficiency of the hydrogen evolution reaction upon contact with surface regions of WSe2 nanocrystals different in atomic packing.

Features of thermochemical treatment of nanostructured tungsten trioxide (WO3) films in hydrogen sulfide aimed at the formation of tungsten disulfide (WS2) nanolayers in the hybrid WS2/WO3 structure are investigated. The effect of temperature and treatment time on the structure, chemical state, morphology, and optical properties of the WS2/WO3/FTO photocathode (on the fluorinated tin oxide substrate), as well as on its photoelectrocatalytic activity in the reaction of hydrogen evolution in an acidic solution has been established. It is shown that sulfurization of nano-needle WO3 films under optimal conditions leads to the formation of a nanocrystalline hybrid WS2/WO3 structure that ensures the separation of photogenerated carriers (electrons and holes) at interphase boundaries (heterojunctions). This facilitates the efficient photo-activated hydrogen evolution reaction according to the Z-scheme. First-principal calculations of the thermodynamic properties of the hybrid WS2/WO3 nanocatalyst showed that a synergistic effect of nanophases is possible. This increases the catalytic activity of hydrogen evolution on both the basal planes of WS2 nanoclusters and the surface of metal oxide nanoclusters.

Approaches to the technology developed by OKBM Afrikantov for creating a supercomputer twin of a nuclear power plant on the basis of a three-level model are described. A software implementation of this technology based on homegrown software is proposed. Experience in using the technology is shown for the Yasen-M project, RITM-200, and BN-800.

MoS2 nanofilms were created by thermochemical processing (sulfurization) of thin-film Мо and МоОу precursors in S vapor. The precursor films were created by pulsed laser deposition. The obtained molybdenum disulfide films consisted of 2H-MoS2 nanocrystals with laminar packing of basal planes oriented perpendicular to the film surface. The increase in the sulfurization temperature from 500°C to 800°C provided better quality of local packing and, as a consequence, reduction of electric resistance, higher concentration of carriers (electrons) and their mobility. The application of metal oxide precursor МоОу resulted in higher efficiency of synthesis of high quality MoS2 nanofilms. The efficiency of activation of the electrochemical processes of hydrogen production in an acidic solution was lower with crystalline MoS2 nanofilms than with amorphous MoSx films. Nanocrystalline MoS2 films, however, manifested improved photo- and electrocatalytic characteristics in activation of reactions of hydrogen and oxygen evolution in an alkaline solution.

The mechanisms of film formation during pulsed laser ablation of a MoS2 target were studied. The conditions for the deposition of laser erosion plume were determined. This made it possible to obtain coatings with a porous structure consisting of round Mo nanoparticles coated with a thin shell of amorphous molybdenum sulfide MoSx > 2. Due to its hybrid structure, the MoSx > 2/Mo nanomaterial can be effectively used for electro- and photocatalysis of water splitting. The MoSx > 2/Mo films deposited on a glassy carbon substrate are characterized by good current transport and high active surface area. When the film thickness increased due to the increased deposition time, the overvoltage of hydrogen evolution in an acid solution monotonically decreased to 142.5 mV, which was necessary in order to obtain current density of hydrogen evolution of 10 mA/cm2. The catalyst loading was 230 μg/cm2. Further increase in the loading did not significantly reduce the overvoltage. The results indicate that it is promising to use Mo nanoparticles as an ultrafine support for the catalytic nanolayers of amorphous molybdenum sulfide.

The possibility of using physicochemical methods for treating a nickel foam to increase its electrocatalytic activity in hydrogen and oxygen evolution reactions in an aqueous alkaline solution was studied. The modification of a 1-mm-thick sheet of the foam was carried out through its surface and included physical deposition of pulsed laser plasma for the formation of catalytic MoSx and MoSxSey films, followed by their annealing. The effect of foam pretreatment by sulfurization in H2S under varying conditions and formation of catalytic layers with different structures and compositions was studied. The best improvement in the electrocatalytic performance of the foam was exerted by thin-film coatings of molybdenum sulfide and sulfide/selenide with a nanocrystalline structure formed on the surface of a foam with a Ni3S2 underlayer. The possibility of a synergetic effect of the formed phases was analyzed by DFT calculations. For the optimum composition of the modified layers, the overvoltage of H2 evolution (for a current density of 10 mA/cm2) decreased to 155 mV, and the overvoltage of O2 evolution did not exceed 160 mV. The electrocatalytic characteristics obtained by this treatment are not inferior to those for the best modern electrocatalysts created on nickel foam by widely used methods of hydrothermal synthesis or electrodeposition.

To obtain Mo–S–C thin-film coatings on steel substrates with varying structural and chemical states, pulsed laser codeposition method was used at room temperature, including the first ever use of reactive codeposition of Mo and C in H2S. The conditions are determined for obtaining sufficiently smooth layers with optimal local packing of atoms in amorphous MoSx and diamond-like carbon nanophases, which yielded relatively high wear resistance and a low sliding friction coefficient (~0.1) in air without a long running-in phase.

We present the results of a comparative investigation of the friction and wear characteristics of MoSx and MoSex coatings in an oxidizing medium (argon–air mixture) at a temperature of –100°C. Thin films of these solid lubricants were manufactured by pulsed laser deposition using MoS2, MoSe2, and Mo targets in vacuum and H2S. It was established that S-containing coatings ensured a friction coefficient of ~0.09 and were much superior to S-containing coatings in respect of wear. The properties of MoSx coatings depended on the concentration of S that determined the local atomic packing in the amorphous structure of the film. The friction coefficient of MoS3 coating after running-in was half as small as that of MoS2 and amounted to 0.08.

The ability to increase the efficiency of electrochemical H2 and O2 evolution reactions in an alkaline solution using nickel-foam-based electrodes has been studied. To improve the catalytic properties of the foam, it was subjected to complex modification via sulfurizing in sulfur-containing gaseous media and the additional formation of amorphous or crystalline MoSx nanolayers. The foam was sulfidized in hydrogen sulfide or sulfur vapor at a temperature of 400°C. Amorphous MoSx films were produced via pulsed laser deposition from a MoS2 target in an H2S atmosphere. To obtain nanocrystalline catalytic MoSx layers, thin-film Mo precursors were preliminarily applied to the foam pre-sulfurized in sulfur vapor at 400°C. The deposition of precursors was carried out in vacuum at 22°C. After deposition, the foam with precursors was oxidized in air at 600°C. The modified samples were probed via scanning electron microscopy involving microanalysis and Raman spectroscopy. The effect of the precursor layer thickness on the sulfurizing efficiency and phase composition of the modified layers was established. The amorphous layer deposition was found to have a strong impact on only the O2 evolution. The crystalline layers obtained via sulfidizing of Mo-containing precursors exerted influence on both the cathodic and anodic reactions. The hydrogen overvoltage at a current density of 10 mA/cm2 was −160 mV, and the oxygen overvoltage was below 150 mV, which corresponded to the best electrocatalysts on the nickel foam after the volume modification via conventional chemical treatment (hydro- and solvothermal synthesis).

Noble transition metal dichalcogenides (TMDCs) such as PtS2 and PtSe2 show significant potential in a wide range of optoelectronic and photonic applications. Noble TMDCs, unlike standard TMDCs such as MoS2 and WS2, operate in the ultrawide spectral range from ultraviolet to mid-infrared wavelengths; however, their properties remain largely unexplored. Here, we measured the broadband (245–3300 nm) optical constants of ultrathin PtS2 and PtSe2 films to eliminate this gap and provide a foundation for optoelectronic device simulation. We discovered their broadband absorption and high refractive index both theoretically and experimentally. Based on first-principle calculations, we also predicted their giant out-of-plane optical anisotropy for monocrystals. As a practical illustration of the obtained optical properties, we demonstrated surface plasmon resonance biosensors with PtS2 or PtSe2 functional layers, which dramatically improves sensor sensitivity by 60 and 30%, respectively.

Atomically thin transition metal dichalcogenides (TMDCs) present a promising platform for numerous photonic applications due to excitonic spectral features, possibility to tune their constants by external gating, doping, or light, and mechanical stability. Utilization of such materials for sensing or optical modulation purposes would require a clever optical design, as by itself the 2D materials can offer only a small optical phase delay – consequence of the atomic thickness. To address this issue, we combine films of 2D semiconductors which exhibit excitonic lines with the Fabry-Perot resonators of the standard commercial SiO2/Si substrate, in order to realize topological phase singularities in reflection. Around these singularities, reflection spectra demonstrate rapid phase changes while the structure behaves as a perfect absorber. Furthermore, we demonstrate that such topological phase singularities are ubiquitous for the entire class of atomically thin TMDCs and other high-refractive-index materials, making it a powerful tool for phase engineering in flat optics. As a practical demonstration, we employ PdSe2 topological phase singularities for a refractive index sensor and demonstrate its superior phase sensitivity compared to typical surface plasmon resonance sensors.

The article describes the main achievements in the study of ulcerative colitis (UC) - a disease known since ancient times. «Bloody» non-epidemic diarrhea was described by Hippocrates. The first detailed description was made by K. Rokitansky in 1842. In 1875, S. Wilks and W. Mason first studied the pathomorphology of the colon in UC. The term «non-specific ulcerative colitis» was proposed by the Russian surgeon A. S. Kazachenko in 1913 at the 13th Congress of Russian surgeons. The historical excursion presents the main stages and achievements of surgical treatment of UC.

AIM: to evaluate the efficacy, safety and drug tolerance of «Colokit» for bowel cleansing before colonoscopy.PATIENTS AND METHODS: an open prospective non-randomised study of the quality of bowel cleansing was carried out in 30 patients (17 females, aged 26-72 years), who underwent diagnostic colonoscopy after using «Сolokit» (Mayoly Spindler, France) using two different regimes (recommended and alternative).RESULTS: the quality of the bowel cleansing was significantly better in patients after «Colokit» use in recommended regime vs alternative regime. No difference in subjective assessment of patients’ comfort during bowel preparation was found in both regimes. CONCLUSION: the «Colokit» agent provides good preparation and patients’ comfort and can be recommended for the bowel cleansing before colonoscopy.

The morphology, chemical composition, microstructure, and electrical properties of BC3 thin films subjected to melting by a nanosecond laser pulse are investigated. The original films have been created by pulsed laser codeposition of B and C onto a sapphire substrate at 150 and 350°C. Morphological changes in the films depended on their initial structural state. However, a “frozen” structure of both films after irradiation corresponded to the B-saturated graphite-like phase, the local composition of which varied due to the formation of inclusions of amorphous boron carbide. Before and after irradiation, the films exhibited a slightly decreasing dependence of the surface resistance with increasing temperature from 4.2 to 330 K. After laser irradiation, the films resistance has decreased by a factor of ~2.6.

Relatively low and high deposition rates of BCх films were realized by pulsed laser ablation of mixed B–diamond and dual B–graphite targets, respectively. Deposition was performed at 500 °C and the rate of film deposition was determined with respect to the number of atomic monolayers (obviously less or more than one monolayer) grown for one laser pulse. In the case of BCх films formation with a low deposition rate, doping with B facilitated the growth of the nanocomposite structure, which possessed an increased fraction of sp3 bonds, a very low electrical resistance, and an improved mechanical performance. The change of the sheet resistance of these films as the temperature was reduced from 300 to 65 K had a metallic character. For about 95-nm-thick films with bulk compositions of BC1.7 and BC0.6, the resistivity at room temperature were approximately equal to 1.5 mΩ·cm, and the lowest resistivity of 0.23 mΩ·cm was detected for B-enriched film at 85 K. With an increase in the B atom concentration in such films, the charge carrier (holes) concentration decreased, and their mobility increased from 180 to 10,500 cm2·V−1·s−1 due to samples cooling. The application of a higher deposition rate from the dual B–graphite target activated surface migration of condensed atoms, which caused the development of granular morphology, the B segregation and the reduction of the sp3 bond fraction. The hardness and electrical conductivity of such films were obviously inferior to those of the films obtained by PLD with a low deposition rate.

Hydrogen sensors were fabricated with a well-known structure, formed by depositing WOx films (with or without an additional Pt overlayer) onto SiC substrates. These sensors differed in terms of the morphology and nanostructure of the WOx films, which were pulsed laser deposited (PLD) under varying conditions. The sensory characteristics of WOx/SiC and Pt/WOx/SiC samples were analyzed using conventional current–voltage measurements. In addition, the possibility of detecting an electrical signal in these structures without applying an external voltage (EMF-powered mode) was investigated. The sensor response strongly depended on the qualities of the metal oxide film, including its strength, uniformity, continuity, and adhesion to the SiC substrate. Optimization of the PLD allowed the formation of triclinic WOx 27 times. The highest voltage detected for an external load of 1 kΩ was ~400 μV. The Pt film deposition markedly worsened the sensory properties of Pt/WOx/SiC structures measured by the EMF-powered mode. Possible mechanisms of the appearance of the EMF in the prepared structures are considered.

Graphene is a promising building block material for developing novel photonic and optoelectronic devices. Here, we report a comprehensive experimental study of chemical-vapor deposited (CVD) monolayer graphene’s optical properties on three different substrates for ultraviolet, visible, and near-infrared spectral ranges (from 240 to 1000 nm). Importantly, our ellipsometric measurements are free from the assumptions of additional nanometer-thick layers of water or other media. This issue is critical for practical applications since otherwise, these additional layers must be included in the design models of various graphene photonic, plasmonic, and optoelectronic devices. We observe a slight difference (not exceeding 5%) in the optical constants of graphene on different substrates. Further, the optical constants reported here are very close to those of graphite, which hints on their applicability to multilayer graphene structures. This work provides reliable data on monolayer graphene’s optical properties, which should be useful for modeling and designing photonic devices with graphene.

We studied the possibility of using pulsed laser deposition (PLD) for the formation of a MoSx/WSe2 heterostructure on a dielectric substrate. The heterostructure can be employed for effective solar water splitting to produce hydrogen. The sapphire substrate with the conducting C(B) film (rear contact) helped increase the formation temperature of the WSe2 film to obtain the film consisting of 2H-WSe2 near-perfect nanocrystals. The WSe2 film was obtained by off-axis PLD in Ar gas. The laser plume from a WSe2 target was directed along the substrate surface. The preferential scattering of selenium on Ar molecules contributed to the effective saturation of the WSe2 film with chalcogen. Nano-structural WSe2 film were coated by reactive PLD with a nanofilm of catalytically active amorphous MoSx~4. It was established that the mutual arrangement of energy bands in the WSe2 and MoSx~4 films facilitated the separation of electrons and holes at the interface and electrons moved to the catalytically active MoSx~4. The current density during light-assisted hydrogen evolution was above ~3 mA/cm2 (at zero potential), whilst the onset potential reached 400 mV under irradiation with an intensity of 100 mW/cm2 in an acidic solution. Factors that may affect the HER performance of MoSx~4/WSe2/C(В) structure are discussed.

Aim: to estimate the quality and availability of medical care for patients with ulcerative colitis (UC) and Crohn’s disease (CD), to assess the impact of the economic burden of these diseases on the healthcare budget of Russia and to systematize the main problems in the organization of medical care and drug supply for patients with inflammatory bowel diseases (IBD).Regional IBD databases (2016-2018), official statistical databases, costs of treatment and results of expert interviews with specialists in IBD were used in the study.The analyzed databases showed 104,668 patients with UC in Russia in 2018 (prevalence rate 71 per 100,000 people) and 66,647 patients with CD (prevalence rate of 45 per 100,000 people). The economic burden including agents for biologic therapy (ABT) for the UC was 39.54 billion rubles a year (495 rubles per capita), and CD - 32.98 billion rubles a year (378 rubles per capita). It requires an additional 9.87 billion rubles annually for UC and 9.20 billion rubles annually for CD patients to provide the complete supply with ABT.The annual burden of IBD is 72.52 billion rubles, which is comparable to the costs of other socially significant diseases, including malignant tumors. It shows the high social and economic value of IBD for the country. The main problems of medical care and drug supply for IBD patients are the mismatch of official statistical data and real IBD prevalence in Russia due to absence of comprehensive register and the insufficient supply with ABT due to limited funding. A federal center for IBD should be founded for better quality of registration, for the precise monitoring and for the active management of personal drug supply.

This work studies the factors that affect the efficiency of the photoelectrochemical hydrogen evolution reaction (HER) using MoSx/WO3 nano-heterostructures obtained by reactive pulsed laser deposition (RPLD) on glass substrates covered with fluorinated tin oxide (FTO). Another focus of the research is the potential of MoSx nanofilms as a precursor for MoOz(S) nanofilms, which enhance the efficiency of the photo-activated oxygen evolution reaction (OER) using the MoOz(S)/WO3/FTO heterostructures. The nanocrystalline WO3 film was created by laser ablation of a W target in dry air at a substrate temperature of 420 &deg, C. Amorphous MoSx nanofilms (2 &le, x &le, 12) were obtained by laser ablation of an Mo target in H2S gas of varied pressure at room temperature of the substrate. Studies of the energy band structures showed that for all MoSx/WO3/FTO samples, photo-activated HER in an acid solution proceeded through the Z-scheme. The highest photoelectrochemical HER efficiency (a photocurrent density ~1 mA/cm2 at a potential of ~0 V under Xe lamp illumination (~100 mW/cm2)) was found for porous MoS4.5 films containing the highest concentration of catalytically active sites attributed to S ligands. During the anodic posttreatment of porous MoSx nanofilms, MoOz(S) films with a narrow energy band gap were formed. The highest OER efficiency (a photocurrent density ~5.3 mA/cm2 at 1.6 V) was detected for MoOz(S)/WO3/FTO photoanodes that were prepared by posttreatment of the MoSx~3.2 precursor. The MoOz(S) film contributed to the effective photogeneration of electron&ndash, hole pairs that was followed by the transport of photoelectrons from MoOz(S) into the WO3 film and the effective participation of holes possessing strong oxidation ability in the OER on the surface of the MoOz(S) film.

We studied the tribological properties of amorphous molybdenum sulfide (MoSx) thin-film coatings during sliding friction in an oxidizing environment at a low temperature (&minus, 100 &deg, C). To obtain films with different sulfur contents (x ~ 2, 3, and 4), we used reactive pulsed laser deposition, where laser ablation of the Mo target was performed in H2S at various pressures. The lowest coefficient of friction (0.08) was observed during tribo-testing of the MoS3 coating. This coating had good ductility and low wear, the wear of a steel counterbody was minimal. The MoS2 coating had the best wear resistance, due to the tribo-film adhering well to the coating in the wear track. Tribo-modification of the MoS2 coating, however, caused a higher coefficient of friction (0.16) and the most intensive wear of the counterbody. The MoS4 coating had inferior tribological properties. This study explored the mechanisms of possible tribo-chemical changes and structural rearrangements in MoSx coatings upon contact with a counterbody when exposed to oxygen and water. The properties of the tribo-film and the efficiency of its transfer onto the coating and/or the counterbody largely depended on local atomic packing of the nanoclusters that formed the structure of the amorphous MoSx films.

Structural features of CBx films obtained by pulsed laser ablation of targets made of pressed diamond powder with boron-powder additions at B/C atomic ratio of x = 0.33 have been studied. The films were deposited on heated substrates, so that diffusion processes involving C and B atoms on the surface and in the volume of films were possible. Selected conditions of film deposition ensured their effective doping with boron (0.4 ≤ x ≤ 0.6). The incorporation of B atoms was accompanied by the formation of B–C chemical bonds, whereas the formation of sp2 graphite bonds and their ordering in clusters with laminar packing was suppressed. The films possessed very low resistivity (~1.4 mΩ cm) at room temperature and exhibited metallic type of conductance on decreasing the temperature to 77 K.

Pulsed laser ablation of a MoS2 target causes enhanced splashing of the material. So, for MoSx films obtained by pulsed laser deposition (PLD) in the conventional normal incidence (NI) configuration, their typical morphology is characterized by an underlying granular structure with an overlayer of widely dispersed spherical Mo and MoSx particles possessing micro-, sub-micro- and nanometer sizes. We investigated the possibility of using high surface roughness, which occurs due to particle deposition, as a support with a large exposed surface area for thin MoSx catalytic layers for the hydrogen evolution reaction (HER). For comparison, the HER performance of MoSx layers formed by grazing incidence (GI) PLD was studied. During GI-PLD, a substrate was placed along the direction of laser plume transport and few large particles loaded the substrate. The local structure and composition of thin MoSx layers formed by the deposition of the vapor component of the laser plume were varied by changing the pressure of the buffer gas (argon, Ar). In the case of NI-PLD, an increase in Ar pressure caused the formation of quasi-amorphous MoSx (x ≥ 2) films that possessed highly active catalytic sites on the edges of the layered MoS2 nanophase. At the same time, a decrease in the deposition rate of the MoSx film appeared due to the scattering of the vapor flux by Ar molecules during flux transport from the target to the substrate. This effect prevented uniform deposition of the MoSx catalytic film on the surface of most particles, whose deposition rate was independent of Ar pressure. The scattered vapor flux containing Mo and S atoms was a dominant source for MoSx film growth during GI-PLD. The thickness and composition distribution of the MoSx film on the substrate depended on both the pressure of the buffer gas and the distance from the target. For 1.0–2.5 cm from the target, the deposition rate was quite sufficient to form S-enriched quasi-amorphous MoSx (2.5

To fabricate an electrocatalyst containing nanostructured layers of WOy and MoS x , a sequential formation of tungsten oxide and molybdenum sulfide thin films is performed by means of the pulsed laser deposition of W and Mo in low-pressure air and hydrogen sulfide media, respectively. The reactive medium pressure and the substrate (glassy carbon) temperature are varied during and after the deposition. WOy thin films of various morphologies and structures determining certain differences in their catalytic properties in the reaction of hydrogen evolution in acidic solutions are obtained. However, the catalytic efficiency of the obtained WO y nanoelements (spheres, needles, and sheets) with amorphous and crystalline structures appears to be insufficient. Additional deposition of MoS x with an amorphous structure results in a significant improvement of the catalytic properties. Sulfur atoms in the MoSx amorphous matrix cause the formation of catalytically active sites, while the developed surface of the WO y stimulates an increase in the catalyst total active area. Penetration of hydrogen effectively formed on MoS x into the bulk of thin films of WO y provides a crucial electrocatalysis condition—low current resistance in the support layer with a large exposed surface area.

Experimental results from the synthesis of diamond-like BC x compounds with the aid of high-pressure techniques and laser sputtering methods are presented. A combination of unique characteristics in these compounds can be attained by varying the B/C ratio. The possibility of sputtering carbon films of micron or nanosize thickness with high boron content opens up a way to use such materials on industrial scales. Hetero-diamonds with high boron content have high elastic moduli and boron-doped diamond polycrystals possess metallic conductivity.

The peculiarities of pulsed laser ablation of MoSe2 targets which caused the formation of a complex plume containing atoms (Mo and Se) and Mo nanoparticles (Mo-NPs) have been studied. Investigations of the composition, structure, and catalytic activity toward the hydrogen evolution reaction (HER) for MoSex/Mo-NPs films prepared by pulsed laser deposition (PLD) in a vacuum and in a buffer He gas were carried out. For He pressure of 30 Pa, a shock wave could be the dominant mechanism of material transport, resulting in the deposition of an Se-enriched flux of chemically active atoms and leading to the growth of amorphous films with an increased Se content. Mo nanoparticles allowed for a larger surface area of the MoSex∼3.1/Mo-NPs catalyst deposited 5 cm from the target. However, for deposition in He at 10 cm, the amount of Mo NPs in the film appreciably decreased. Factors that could impact on the transport of nanoparticles through a buffer gas were considered. The amorphous MoSex∼3.1/Mo-NPs films prepared by PLD in He gas exhibited excellent HER performance. Quasicrystal MoSex

This paper presents experimental results on the synthesis of boron rich diamond-like carbon phases (BCx) obtained by high pressure sintering (s-BCx) and pulsed laser deposition (PLD-BCx). It has been shown that sintering of a mixture of a powder of micro-diamonds with a powder of boron in the toroid type high pressure device leads to the creation of s-BCx phase with a low resistivity, and high elastic moduli. The PLD-BCx film found to be rigid with the resistivity as low as that of best conductive boron–doped diamond films. It indicates that the presence of B atoms in a laser plasma leads to the formation of sp3 bonds in the material in the process of chemical sputtering. The combination of unique characteristics can be achieved by changing the ratio B/C.

We report the preparation of MoS x thin films with reactive pulsed laser deposition (RPLD), an original technique that allows us to investigate the correlation between key MoS x properties, such as the composition, morphology, and local structure, and the catalytic performance in the hydrogen evolution reaction (HER). The use of two geometries of normal angle (NA) and sliding angle (SA) for the deposition by laser plume from a Mo target on a glassy carbon substrate made it possible to regulate the characteristics of MoS x films (1.5 ≤ x ≤ 10) by varying the H 2 S pressure and thus to circumvent the limitations inherent in traditional pulsed laser deposition. Amorphous MoS x , quasi-crystalline layered MoS 2 , disordered as well as rather perfect Mo 3 –S clusters, and sulfur clusters were formed. The films containing locally ordered clusters with a higher content of bridging S 2 2 − and apical S 2 − ligands could be prepared by SA RPLD. This film was demonstrated to be the most efficient electrocatalyst, possessing a lower overpotential of − 130 mV at a current density of − 1 mA/cm 2 , a Tafel slope of 44 mV/dec, and a quite high exchange current density of ~ 1.2 μA/cm 2 . The preparation of a low-resistance MoS x underlayer by NA RPLD made it possible to increase the catalytic performance of a bilayer coating by 10%.

We have studied the characteristics of the structure, composition, and electrocatalytic properties of thin MoS x films obtained by pulsed laser deposition using an Mo target ablated in H2S reactive-gas medium. The laser plume during deposition was directed tangentially and normally to the substrate, which allowed amorphous films to be obtained with different local atomic packings in an amorphous matrix consisting of Mo3–S clusters. It is established that the orientation of Mo3–S clusters influences charge transport in the catalyst and determines the type and surface density of catalytically active sites in the reaction of hydrogen evolution. For small, approximately equal amounts of Mo and Pt (~4 μg/cm2) laser-deposited on glassy carbon substrates, the MoS x films were inferior to a Pt film with respect to hydrogen overvoltage (by about 90 mV) in acid solution, but the efficiency of thin-film MoS x catalysts at elevated cathode potentials exceeded that of a thin Pt film.

Pulsed laser ablation of MoS2 and WO3 targets at appropriate pressures of background gas (Ar, air) were used for the preparation of new hybrid nanostructured catalytic films for hydrogen production in an acid solution. The films consisted of a nanostructured WO3&minus, y underlayer that was covered with composite MoS3/np-Mo nanocatalyst. The use of dry air with pressures of 40 and 80 Pa allowed the formation of porous WO3&minus, y films with cauliflower- and web-like morphology, respectively. The ablation of the MoS2 target in Ar gas at a pressure of 16 Pa resulted in the formation of amorphous MoS3 films and spherical Mo nanoparticles. The hybrid MoS3/np-Mo//WO3&minus, y films deposited on transparent conducting substrates possessed the enhanced (photo)electrocatalytic performance in comparison with that of any pristine one (MoS3/np-Mo or WO3&minus, y films) with the same loading. Modeling by the kinetic Monte Carlo method indicated that the change in morphology of the deposited WO3&minus, y films could be caused by the transition of ballistic deposition to diffusion limited aggregation of structural units (atoms/clusters) under background gas pressure growth. The factors and mechanisms contributing to the enhancement of the electrocatalytic activity of hybrid nanostructured films and facilitating the effective photo-activation of hydrogen evolution in these films are considered.

The effect of pulsed laser annealing (PLA, i.e., action of nanosecond laser pulses in air atmosphere) on surface morphology, structure, chemical state, and electrical properties of thin films consisting of boron and carbon atoms was studied. The nanolayered В/С and mixed ВСx~3 thin film precursors (with a thickness ~110–140 nm) were created on sapphire substrates by using the pulsed laser deposition. Scanning electron microscopy and Raman scattering measurements indicate that the process of stratification of the multilayer B/C films dominated during PLA of the films. The outer layers were removed, and closer to the substrate, the B and C layers were preserved, and they were not mixed. For the mixed ВСх films deposited at elevated temperatures, the PLA treatment enhances ordering of initially amorphous film structure. At the stage of melting of these films, oxygen (from surrounded air) penetrated inside the top layer of the film leading to the formation of a multiphase structure from g-BCx and B-doped GO/rGO after solidification. Studies of the chemical state of elements in the irradiated film have shown that О atoms, which penetrated the under-surface layers of the film, facilitated the formation of new chemical bonds in the B–C–O system. The concentration of O atoms in the depth of the film could reach 8%. The preferential oxidation of boron in a homogeneous mixture of B–C–O atoms indicated that intercalation of carbon matrix could be due to the incorporation of not only O atoms, but also B–O molecules. The laser irradiated ВСх films have a relatively low resistivity (~1.6 mΩ·cm) and semi-metallic dependence on temperature in the range 4.2–300 К. The spatial distribution of conductivity zones after PLA has an irregular structure, and its pattern looks like sand dunes, indicating that the PLA treatment leads to mixing zones of high with those of lower conductivity. The contact-tip resistivity inside the areas of high conductivity of the ВСx/Al2O3 samples may be significantly lower than that of pure graphite.

The article describes the technology of the supercomputer twin of a nuclear power plants, which describes the main circulation circuit of the coolant. The technology is based on a joint one-dimensional and three-dimensional description of a reactor expanding the field of application of traditional one-dimensional system codes for describing fundamentally three-dimensional processes in reactor plenum. A description of the technology and verification data based on experimental studies is provided. The application of this technology to the analysis of the partial operating modes of the RITM-200 reactor plant was demonstrated, which made it possible to mitigate power limitations when disconnecting part of the heat exchange surface of the steam generator, reduce the costs of repair of the reactor plant associated with the replacement of steam generator cassettes, and avoid prolonged shutdown of a nuclear icebreaker.

Laser-initiated modification of the structure and morphology of the MoS2 and MoSe2 targets used to obtain antifriction thin-film coatings by pulsed laser deposition were studied. Significant differences were revealed in the ablation mechanism of these materials that caused important differences in the structure formation of MoS x /Mo and MoSe x /Mo coatings containing submicro- and nano-scaled Mo particles. Results of the study of structure, morphology and tribological properties of these coatings (coefficient of friction, wear resistance) when testing by the technique of sliding the ball over the covered disk under different air humidity and temperatures are presented. Comparative studies have revealed the superiority of the MoSe x /Mo coatings over the MoS x /Mo coatings during sliding friction under varying conditions of applications in frictional unites.

The results of structural and electrochemical studies of thin Mo-S-P films obtained by pulsed laser deposition at various conditions from a target made of mixture of MoS2 and P powders are presented. For variation of S/P ratio and modification structure of the catalytic films, the deposition of the laser plume was conducted in vacuum, in Ar and H2S gas. The highest electrocatalytic properties for activating the hydrogen evolution reaction in an acid solution were found for composite amorphous/nanocrystalline MoS6P/nc-Mo films. In the chemical stateof S 2p, the high binding energy dominated. The doping of the films with phosphorus increased the efficiency of the reaction compared with that of MoS x /nc-Mo films. The analysis of the synergistic effect of phosphorus on the performance of amorphous MoS x P y films in H2 evolution was carried out using the density functional theory.

Turbulent Rayleigh–Benard convection in cubic cells is studied experimentally using two similar but not identical experimental setups in different laboratories. Both teams have made experiments for the same set of Prandtl and Rayleigh numbers (Pr = 3.5, Pr = 6.1, Ra = 2.0 · 10 9 , Ra = 6.0 · 10 9 , Ra = 1.6 · 10 10 ). Experiments showed that the structure of the mean flow and local characteristics of turbulent pulsations are robust and do not depend strongly on the technical details of experimental setup. Periodic low-frequency oscillations and orientations of large-scale circulation (LSC) are more sensitive to the experimental setup design. Long-time measurements using differential thermocouples revealed that preferential orientation of LSC is along of one of the diagonals, however it can deviate from exact diagonal orientation. Analyses of temperature and velocity measurements showed that dominant periodic oscillations of LSC can not be explained as simple modulation of the intensity of the large-scale diagonal flow because most intense oscillations are observed in the direction, which is orthogonal to the plane of LSC. Experimental data obtained independently by two teams can be used as a benchmark for CFD codes. Numerical simulation using a standard widely-spread CFD code was carried out. In general, on the base of overall comparison between experimental and large-eddy simulation results we concluded that for the described regimes LES gives satisfactory agreement with experiment reproducing the small-scale dynamics of the turbulent flow and the behavior of LSC.

It has been found that the pulsed laser deposition of a thin tungsten selenide film, followed by thermal treatment at 550°C in an Ar + O2 mixture of gases, results in the formation of a hybrid structure that is made up of ultrathin WSe2 and WO3–y platelets. The structural and size characteristics of the nanoplatelets deposited on microcrystalline graphite provide the effective hydrogen evolution reaction in a 0.5 M H2SO4 solution, with the cathode current made about seven times higher at a potential of–100 mV and the slope of the Tafel characteristic reduced from 340 to 90 mV/dec.

We demonstrate the possibility of fabricating high-efficiency semiconductor hydrogen detectors based on tangsten-oxide thin films deposited onto silicon-carbide crystals by reactive pulsed-laser deposition. The obtained WO3/SiC structures ensure a noticeable voltage shift ΔU on the reverse branch of the I−V characteristics without commonly used catalyst layers of platinum-group metals. The ΔU value reached 2.1 V at a detected hydrogen concentration of 0.2% in air at 350°C. The response times to hydrogen inlet and recovery of the WO3/SiC structure after hydrogen outlet are found to be much shorter than those for the Pt/WO3/SiC structure. The high performances of the fabricated WO3/SiC sensor are due to the layered structure of the orthorhombic phase of tungsten oxide, which consists of loosely packed microcrystalline plates containing nanocrystals smaller than 100 nm.

The introduction of molybdenum nanoparticles in MoSe x thin films formed by pulsed laser deposition led to changes in the film structure. The base planes of the layered atomic packing of the MoSe х matrix around Mo nanoparticles rotated; as a consequence, the edge sites that formed during the “breaking” of the Se–Mo–Se layered atomic packing came out to the film surface. At high nanoparticle concentrations, this effect led to high density of edge sites possessing increased catalytic activity (compared with that of the base planes) for initiating the electrochemical evolution of hydrogen in a 0.5 M H2SO4 solution. Voltammetric measurements at room temperature showed that when the carbon cathode was coated with MoSe x thin films under optimum conditions, the hydrogen overvoltage considerably decreased, and the cathodic current increased. The results indicate that developments in the field of preparation of nanostructured electrodes based on layered transition metal dichalcogenides show promise as an alternative to expensive electrodes based on platinum group metals for electrocatalysts of hydrogen evolution.

The possibility of obtaining new relatively inexpensive electrode materials to provide enhanced efficiency of hydrogen evolution reaction (HER) in an aqueous acid solution was investigated. For this purpose, the surface properties of cathodes made of microcrystalline graphite were modified by pulsed laser deposition of thin films of WSe x . The structure, morphology, and chemical composition of the thin film coatings were varied by changing the deposition conditions and subsequent heat treatment. The compact and dense structure of the film in an amorphous and crystalline state did not result in a marked positive impact on the character of the HER process, which was investigated in 0.5 M H2SO4 solution at room temperature. Formation of thin layers consisting of nanocrystalline “petals” WSe2 caused an increase in cathodic current by more than 6 times (at a voltage of–150 mV), and the Tafel slope of the voltage vs. current curve was reduced by about 80 mV/dec. The conditions were determined to produce on the surface of the graphite cathode a high density of new catalytically active sites that formed on edges of molecular planes forming a layered structure characteristic of WSe2 nanocrystals.

Features of the expansion of a pulsed laser-initiated plasma-vapor plume containing Se and Watoms in buffer gases of different chemical compositions (Ar and He) is investigated. It is found that gas pressure influences the structure and chemical state of the deposited WSex layers. The conditions for preparing coatings with low coefficients of sliding friction and high wear resistance are determined.

The effect of the nanostructure and chemical composition of thin Mo–Se–C films on the run-in of the diamond-like carbon coating (a-C) and the steel counterbody during ball-on-disk sliding test is studied. At the final stage of the deposition of the a-C coating on the steel substrate, a flow of atoms from the MoSe2 target was added to the flow of atoms being deposited. The influence of the air humidity on the selection of optimum structure and chemical composition of the film, which provide a fairly low (

Pulsed laser irradiation (wavelength 1.06 μm) of a molybdenum diselenide target in vacuum caused the formation of Mo-enriched particles on the surface of the target. Nanoparticles ~ 5–50 nm in size were torn from the target and deposited on the substrate. The use of a buffer gas (argon, pressure 5 Pa) increased the thickness of the shells formed around the nanoparticles and modified the chemical composition of the films. Heating the substrate caused the crystallization of the matrix, such that the basal planes were oriented in a direction parallel to the film surface. The orientation of the planes changed in the shells. The edge sites occurred at the film surface, exhibiting the enhanced catalytic activity in hydrogen evolution reaction. The deposition of MoSex/Mo films in a nanocrystalline state on the carbon electrode caused a decrease in the overvoltage of more than 270 mV, and the lowest Tafel slope was 86 mV/dec.

A method of shadow-masked pulsed laser deposition was applied to obtain W–Se and W–Se–C films using pure argon (Ar) gas and a mixture of Ar and methane, respectively. The gas pressure was varied in a range of 2–10 Pa. The deposition in Ar caused the formation of Se-enriched W–Se films (Se/W ∼ 5) with pronounced surface roughness because of an effective nanoparticle growth. Heating or DC/RF biasing the substrate modified the film composition (Se/W ∼ 1.7–4) and surface smoothing. The use of methane resulted in a doping of W–Se–C films with carbon, and the C concentration was increased to ∼67 at.% under RF biasing of the substrate. The films with smooth surface had high coefficients (∼30%) of light reflection. The formation of nanoparticles and density-graded surface texture decreased the reflectance to 3.8%. Antireflective properties and high area of the rough surface may play an essential role in enhancing the photovoltaic and catalytic properties of W–Se films. Dense structure, smooth surface, optimal Se/W ratio, and preferential sp2-bonding of C atoms promote the high tribological performance of nanocomposite W–Se–C coatings.