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Iron(III) salts with saturated monocarboxylic acids: formic, acetic, butyric, valeric, and enanthic acids are synthesized. The compounds obtained are characterized by elemental analysis, infrared (IR) spectroscopy, and differential scanning calorimetry. As a result of thermal decomposition of the synthesized carboxylates, iron-containing nanocomposites are obtained, which are studied by scanning and transmission electron microscopy, elemental analysis, infrared (IR) spectroscopy, energy-dispersive X-ray and Mössbauer spectroscopy, and X-ray phase analysis. The magnetic properties of the obtained nanocomposites are studied.

The paper presents studies aimed at producing a three-component alloy from the powders of cobalt, chromium and molybdenum (66 wt % Co, 28 wt % Cr, 6 wt % Mo), with a stable phase structure by selective laser melting. At the beginning of the work, the initial powders were graded on sieves with mesh sizes of 20-70 µm. The powder mixtures were obtained by mechanical mixing of various fraction powders and mechanical alloying in a planetary ball mill. The samples were produced using the VARISCAF-100MVS selective laser melting unit. The melting process of powder materials was completed in a chamber filled with inert gas argon after preliminary vacuum degassing. The microhardness analysis of the samples before and after the thermal treatment was completed. The results of phase composition studies, X-ray diffraction analysis, scanning electron microscopy are presented. Examination of the X-ray profiles of the samples proves that the obtained alloy mainly contains the epsilon-phase which improves the hardness and the wear resistance of the product.

Abstract: An annotated checklist of aquatic and semiaquatic true bugs (Heteroptera: Nepomorpha, Gerromorpha) of Stavropol Territory is provided, summarizing the species records in the region. The checklist includes 33 species from 17 genera and 10 families. According to the results of collections in the summer of 2022, four species are recorded for the region for the first time: Micronecta pusilla(Horváth, 1895),Sigara iactansJansson, 1983, Hydrometra stagnorum(Linnaeus, 1758), and Microvelia reticulata(Burmeister, 1835). New localities in the region are given for 10 species. The distribution of each species in the North Caucasus is updated.

Abstract: Nickel(II) salts are synthesized with saturated monocarboxylic acids: butyric, valeric, caproic, enanthic, and caprylic. The resulting compounds are characterized by elemental analysis, infrared (IR) spectroscopy, and differential scanning calorimetry. As a result of thermal decomposition of the synthesized carboxylates, nickel-containing nanocomposites are obtained, which are studied by scanning and transmission electron microscopy, elemental analysis, IR spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray phase analysis. The magnetic properties of the obtained nanocomposites are studied.

This paper analyzes the effect of SLM parameters on mechanical characteristics and surface roughness of a single-component copper powder. The study reports on appropriate SLM conditions for a single-component copper powder; to form a layer a technique within layer-by-layer selective laser melting is suggested and comprises roughing, semi-finishing and finishing modes. The work establishes a range to vary surface roughness, porosity and ultimate compressive strength of a single-component copper powder by means of laser processing conditions. Rz is variable 332 to 689 μm, porosity ranges approximately 13-39%, and ultimate compressive strength is 8 to 104 МPа.

ABSTRACTUsing data from official manufacturing censuses, we compare labour productivity in the UK and the Russian Empire around 1908 in the industries in which medium- and large-size enterprises predominated. We find that Russia’s labour productivity was 75.3 or 57.4% of the British level, depending on whether we include or exclude Russia’s large and highly productive spirits industry. Russia’s productivity was between France’s and the Netherlands’, if we include the spirits industry; and between the Netherlands’ and Italy’s, if we exclude it. We find that the majority of Russian industries underperformed the British ones. However, some of the industries that had been established or modernized during the state-induced industrialization policies of the 1890s, including the metallurgy in the Southern industrial region, iron and steel tubes, railway carriages, and butter and cheese, performed on a par with or close to their British counterparts. The remaining modernized industries, including spirits, tobacco, and petrochemical sectors, outperformed their British equivalents. Our findings suggest that although Russia’s aggregate labour productivity lagged behind the UK’s, Russia’s modernized industries achieved, and in some cases surpassed, the productivity level of their British counterparts.

Four various methods of powder feedstock preparation for laser powder bed fusion are compared. Application of commercial spherical powder leads to the formation of single-phased state. Powder mechanically alloyed during 14 minutes in air atmosphere provides conditions for the formation of double-phased state with nonuniform distribution of components in the samples. Mechanical alloying in Ar-atmosphere during 30 minutes leads to the formation of double-phased state with more uniform distribution of components and precipitations of Cr2O3. Preliminary mechanical sieving of the powder allows to produce double-phased samples with nonuniform distribution of components comparable with that in samples produced from powder mechanically alloyed during 14 minutes in air atmosphere. Microhardness of all the studied samples produced from all the studied powders was comparable. All the proposed methods of powder feedstock preparation are applicable in laser powder bed fusion depending on the required properties, elemental and phase composition of the final product.

Magnesium-based materials find their use mainly in manufacturing light-weight constructions in motor-car, airspace industries, and biomedicine due to the low density. This paper provides an overview of introducing magnesium into SLM technology and describes searching experiments to prepare samples of magnesium powder МPF-4 (Russian State Standard 6001-79) conducted in the Laboratory of Yurga Institute of Technology. The study has determined appropriate parameters to synthesize a compact structure: laser output power 100 W, laser beam movement velocity 200 mm/s, scanning pitch 0.1 mm, modulation frequency of laser irradiation m = 2500 Hz, linear energy density Е=5 J/mm2, the process is to be carried out in argon shielding medium.

Selective laser melting (SLM) is a manufacturing technology of metal parts of any shapes with target mechanical properties by means of laser melting. This paper discusses the effect of SLM parameters: laser output power, laser movement velocity, scanning pitch and preheating temperature of a powdered material on surface formation mechanism, namely, its physical configuration when melting cobalt-chromium-molybdenum powdered material Со28Cr3Mo. The study points at structural differences of melted surfaces even under identical process parameters. Several types of surface formation are identified, e.g. homogenous melt, coagulated particles, and shapeless particles. Vapor pressure, Marangoni effect, and heat effect of a melted powder are stated to be key reasons for rough surface. This research is of high importance for understanding the effect of SLM parameters on formation of a target quality surface, positive stability and repeatable accuracy of the process.

Selective laser melting (SLM) is thought to be a prospective manufacturing technology of complex metal components. Formation of coagulated particles when melting is reported to be an important factor for target mechanical properties of the end product. This paper discusses the effect of SLM parameters, including laser output power, laser movement velocity, preheating temperature of the powder, laser beam diameter on the mechanism of forming coagulated particles in melting cobalt-chromium-molybdenum powdered material. The study shows that a rise of power to 60 W at a scanning velocity 6 mm/s causes coagulated particles to expand to 350 μm; that is far bigger than a size of powder in as delivered state (90 μm). The work investigates the effect of mechanical activation of cobalt-chromium-molybdenum powder on dimensions of coagulated particles. The research data can be applied to the improvement of up-to-date optimization approaches to manufacturing process parameters in SLM technology.

The formation of spectra of saturated-absorption resonances on the atomic transitions with level momenta J = 0 - J = 1 and J = 1 - J = 2 are investigated, both numerically and analytically, by the method of unidirectional linearly polarised laser waves in order to determine how the transition openness (radiation branching) affects these spectra. It is shown that, along with quantitative changes, determined by the relaxation constants of levels, value of their splitting, polarisation orientation, and wave intensities, the spectra undergo qualitative changes with a change in the degree of atomic transition openness.

The peculiarities of influence of static load on strength characteristics of polymer concretes based on furfural acetone monomer (FAM) are considered in the article. Resistance of static load fatigue is an independent strength characteristic, which should enter into the practice of mechanical testing of materials possessing elastoplastic properties. The regression equation has been obtained as a result of the experiment on a polymer composite material (PCM), which allowed constructing the response surface of the static loading of the polymer composite material based on the resin FAM. A second-order plan for three factors studying static load of a tested composite material is also presented in the paper. It has been established that the ratio of the polymer component to the filler spreading factor is the fundamental ideas influencing the cyclic durability of polymer concretes, while the thickness of the polymer bonding layer and the coarse aggregate are an insignificant factor.

The presence of the alien water bug species Anisops sardeus sardeusHerrich-Schaeffer, 1849 (Notonectidae) in water basins of the Northwest Caucasus has been confirmed. The specimens of this species were collected on the territory of Maikop in 2017. This is the third find of this species in the South of Russia, and it is the northernmost one in Russia.

The Altai glaciers are natural collectors of global and regional atmospheric pollution. The purpose of this study is to determine the occurrence of heavy metals in high-mountain unexplored glaciers of the Attai and to make attempt to identify a source of lead pollution using its isotopic ratios. Concentrations of heavy metals and isotopic composition of Pb in high-mountain firn from Western Plateau of the Katun' ridge were determined by ICP-MS. The obtained occurrence of heavy metals is comparable with the data on Alpine region. Pronounced variations in concentrations within centimeter depth scales are associated with relative contributions from the different natural and anthropogenic sources of heavy metals fallouts. Measured isotopic ratios of Pb confirm anthropogenic origin of the lead pollution of the Altai high-mountainous region.

For the first time, an alien plant species of African origin—water lettuce (Pistia stratiotesL.)—was found in the ponds of the Republic of Adygea (Northwestern Caucasus). In 2014, we discovered clusters of plants with 16–34 rosettes on the water surface of ponds within the city of Maykop, as well as continuous clumps of the plant up to 1 m2in area each in the coastal zone of the water bodies. The suggested cause of water lettuce occurrence in the urbanized territory is its invasion from aquaculture. Adygea is the southernmost location in Russia in terms of the presence of water lettuce.

Testing and debugging of real equipment is a time consuming task. In particular, in the case of marine robots, it is necessary each time to carry out the transportation and deployment of a robot on the water. Experiments with not yet fully functional prototype of marine robot equipped with expensive hardware is in the meantime very risky. Therefore, the use of simulators is affordable way to accelerate the development of robotic systems from the viewpoint of labor effort and cost of experiments. This paper presents a simulator specifically designed for autonomous unmanned underwater vehicles.

Narrow resonances are observed in the course of recording the individual emission lines of the glow discharge in the mixture of isotopes 20Ne and 22Ne, depending on the strength of the longitudinal magnetic field. The position of resonances in the magnetic scale corresponds to the compensation of the isotopic shift for certain spectral lines due to the Zeeman effect. It is found that the contrast of the resonances is higher for the transitions between the highly excited energy levels, and the resonances themselves are formed in the zone of longitudinal spatial nonuniformity of the magnetic field.

At present, the development of techniques and technology can’t do without innovations in production. This explains the desire of mankind to look for innovative ways to produce different types of products. One of these systems is the production method of selective laser sintering. It is more promising as compared to other rapid prototyping techniques, due to the relative cheapness of materials and time-consuming to produce finished products. This article discusses the method of selective laser sintering, its advantages and disadvantages.

The results of experimental studies of the influence of technological regimes of laser irradiation on the thickness of the surface layer of the sintered aluminum powder PA-4. The basic mode settings that affect the quality of the sintered surface layer - laser power, scanning speed and move the laser beam powder layer. The limits of variation of the thickness of the sintered layer from 0.74 to 1.55 mm by changing the technological conditions of laser processing.

In a modern market economy, rapidly developing production requires a significant reduction of term for development and production of new products, ensuring competitiveness and growth of technical and economic performance while minimizing costs. This led to the idea of using rapid prototyping technology which today is focused on the use of composites. This paper gives a brief description of composites formed using the basic processes of rapid prototyping. The main attention is directed to the methods of forming fiber-reinforced composites.

The paper gives consideration to nitrogen behavior when blowing steel with gaseous nitrogen through bottom and submersible tuyeres. Positive effect of nitrogen on physical and mechanical characteristics of rails is determined provided that nitrogen concentration doesn’t exceed 0.025%. This effect is possible due to formation of high-melting vanadium carbides.

At present the development of methods of layer-by-layer and line-by-line synthesis of finished prototypes and functional products made of powder materials furthers introduction of these technologies into different areas of human activities from light to heavy industry and medicine. The research has been carried out to describe how gamma radiation of the Co60 radioactive isotope and the mechanical activation makes an impact on the copper powder, as well as the nature of sintering by the layer-by-layer laser synthesis. The changes of the structure and properties of the powder, which generally affects the layer-by-layer laser process of products sintering, have been detected.

Quality improvement problem has been considered for a laser sintered surface layer. Purposely built experimental setup was described together with a four-factor experiment design on laser sintering PMS-1 copper powder. A mathematical model describing the effect of laser sintering process parameters on the surface roughness has been proposed. Practical recommendation for improving the quality of the surface layer is given.

The paper presents results of research on a method of determining a geometric condition of a sintered surface using an instrumental digital microscope. The results of experimental studies of effects of laser irradiation technological modes on roughness of the cobalt chrome molybdenum powder DSK-F75 sintered layer are presented. Differentiation of modes of product surface and its internal volume formation into rough, semi-finishing and finishing are proposed.

The research has been carried out to describe how gamma radiation of the Co60 radioactive isotope makes an impact on the copper powder, as well as the nature of sintering by the layer-by-layer laser synthesis. The changes of the structure and properties of the powder, which generally affects the layer-by-layer laser process of products sintering, have been detected.

The paper presents the results of the experiment, describing the effect of mechanical activation of powder Cu and Ni on the nature of their SLS-sintering method. The changes in structure and bulk density of powders after mechanical activation are revealed, which generally has a positive effect on the synthesis process of a product.Intorduction

A review of the species of the genus Micronectafrom the Northwestern Caucasus with a key is provided. The regional distribution of Micronecta griseolaHorváth, M. poweri(Douglas et Scott), and M. pusilla(Horváth) is clarified. Micronecta anatolica anatolicaLindberg is recorded from Russia for the first time.

At present the systems of layer-by-layer laser synthesis of three-dimensional articles are used to advance the introduction of new technologies and to reduce its costs. To produce articles in these systems a powder is applied and sintered layer-by-layer with a laser ray on the basis of a 3D CAD-model. The articles are produced in a particular range of laser action which is experimentally selected for each powder. The utilization of new powders, as well as selection of reasonable technological modes for producing articles of definite quality are vital tasks at present [1, 2].

Metal powders are widely used in many modern technologies, as well as they have been applied in the form of various fillers composites. Recently, in some cases, the preliminary activation of metallic powders is made to improve the compatibility of the filler and the matrix. Undertook a study describe the influence of gamma radiation radioactive isotope Co60 on copper powder. Gamma radiation also affects the character of laser sintering by layer-by-layer synthesis. Through this change was obtained in structure and the properties of the powder. On the whole it affects the process of layering laser sintering products.

The physical processes that form the spectra of saturated absorption resonances at atomic transitions between energy levels with angular momenta J= 1/2 and J= 1 in the field of two unidirectional linearly polarised laser waves are studied analytically and numerically. It is shown that the specific features of the resonance spectra are formed in the Λ-schemes of transitions and manifest themselves in the form of narrow coherent structures – dips due to the magnetic coherence (optical orientation) of the transition levels induced by the optical fields. In this case, the energy levels of the lower state make the main contribution, and the contribution of the transfer of magnetic coherence from the sublevels of the upper state to the lower ones in the resonance amplitude manifests itself as an additive. Conditions are found under which the nonlinear resonance is exclusively coherent. The effect of the saturating wave field on the shape of coherent resonance structures is studied.

Mathematical relation between roughness of the surface layer of the sintered article and layer-by-layer laser sintering modes obtained from experiments conducted using copper powder material PMS-1. Authors suggest that split manufacturing process of an article and its inner part must be split to roughing, semi-finishing and finishing modes.

Problems related to use of Erbium as burnable poison for VVER are discussed. Comparison is made between neutronics characteristics of Uranium-Gadolinium and Uranium-Erbium fuel cycles. The study shows that use of Erbium as burnable poison allows decreasing the peaking factor in the core. Meanwhile residual Erbium at the end of the fuel cycle makes it necessary to increase fuel enrichment. There is made the conclusion of prospects of using Erbium as burnable poison for VVER.

This paper presents the current status of works performed to date to further upgrade fuel assemblies and fuel cycle of WWER-440 reactors, and also considers some innovations – both envisaged and implemented in practice – intended to improve their neutronic and operating parameters. Reactors were assumed to operate at 100% power in a steady-state refueling mode. Trial operation of third-generation fuel assemblies (FA-3), including a comparison between some calculated and measured results, is described as an example illustrating these new developments.

Different approaches are under elaboration aimed at the cost reduction of solar electricity. 3D penetrating emitter solar cells are expected to offer performance enhancement at lower costs, using low carrier lifetime cheaper silicon. Using laser ablation, we have prepared indium–fluorine–oxide/(n+pp+)Cz‐Si/indium–tin–oxide bifacial silicon solar cells with deep (110–120 µm) penetrating V‐shaped emitter with aspect ratio of 3–4 (height to half‐width of the V‐grooves). Compared with the reference cell textured with conventional random pyramids and thus not damaged by laser action, which showed front/rear active area photocurrents of 41.1/33.3 mA cm−2, V‐grooved solar cells showed only slightly less front photocurrent of 40.1–40.7 mA cm−2, whereas the superior rear photocurrent of 34.2 mA cm−2. The latter indicates that deep penetrating emitter is especially useful in the case of bifacial solar cells. The best pseudo‐efficiency for V‐grooved cell of 19.5% with estimated bifaciality of ∼80% was obtained for the cell that has been subjected to the smallest laser action during V‐grooving. In addition, ray‐tracing model was applied to calculate efficiency of light absorption by a V‐grooved silicon solar cell for wavelengths in the range from 400 to 1200 nm. The depth of the grooves was varied from 0.05tto wafer's thickness t. The obtained experimental and computational results confirm that the design of crystalline silicon solar cell based on deep penetrating V‐shaped emitter makes possible to obtain high‐efficiency solar cells even in the case of low‐quality silicon wafers.

Experimental results on fast neutron generation in D(d,n)3He and T(d,n)4He reactions in the SOKOL-P laser facility [1] are presented. Solid targets were irradiated by 1.054 ${\rm \mu} $m, s- or p-polarized laser pulses of energy 5-8 J on target and duration 0.85-2 ps. The peak laser intensity was 0.5-2$ \cdot $1018W/cm2. Flat deuterated plastic (CD$_{2})_{\rm n}$targets and Ti D\alpha T\betatargets were used in experiments. Some experiments were carried out with additional targets placed in front of and behind the laser target. The used (TOF) time-of-flight technique helped identify neutrons from D(d,n)3He and T(d,n)4He reactions. Yields up to 106 DD-neutrons and 107DT-neutrons were measured. Interaction of the fast ion beam with the target can explain the observed yield.

We present the results of experimental investigation of ion and electron fluxes produced by irradiating thin foils with laser USPs. These experiments were carried out on the Sokol-P laser facility (pulse duration [?]1 ps, power [?]20 TW) using lavsan, aluminium, and copper targets of equal thickness ([?]5 um). Ions were recorded employing Thomson spectrometers and a time-of-flight spectrometer with a silicon semiconductor detector. To record electrons, use was made of electron spectrometers involving the rotation of particle trajectories by 180deg in magnetic field. The ionic composition of the charged particle beam was determined and the beam shape was investigated in relation to the target material.