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Results of an experimental study of the strength characteristics and structural-phase composition of a nondetachable connection of disparate materials based on thermally hardened aluminum alloys D16T of the Al-4,4Cu-1,5Mg system and 1420 of the Al-5,2Mg-2,1Li system obtained by butt-end laser welding are reported. The phase composition of the welded joint is studied with the use of synchrotron radiation by the method of transmission diffraction. The welded joint microstructure is considered by optical microscopy. It is demonstrated that heat treatment (quenching and artificial aging) allows one to improve the chemical properties of the welded joint.

The finite element method is used to develop a computational algorithm for solving a limited class of problems on the bending of composite plates reinforced with systems of unidirectional high-strength fibers. It is assumed that a neutral plane exists in the region of the plate and behaves similarly to a flexible nondeformable membrane. The displacements of the plate in the longitudinal direction are linear in thickness. In the case of fiber composites of different modulus with different elastic properties under tension and compression, the neutral plane, generally speaking, does not coincide with the median plane. The problem of minimizing the elastic energy functional in accordance with the Lagrange variational principle yields a fourth-order elliptic differential equation for the deflection. The bending stiffnesses of the plate included in the coefficients of the equation are calculated with account for the fact that the elastic characteristics of the reinforcing fibers under tension and compression are significantly different. The numerical solution of the equation is obtained via the finite element method with the help of a Bell triangular element. The paper presents computational results for the bending of rectangular laminated plates in which the fibers are laid in different directions.

A mathematical model has been developed for calculating the relaxation of residual stresses in a surface-hardened prismatic sample in creep under biaxial loading. The calculation results were verified against experimental data for a surface-hardened sample of EP742 alloy after ultrasonic hardening under creep conditions at a temperature of 650oC for 100 h. A detailed theoretical analysis of the influence of the type of stress state on the relaxation of residual stresses during thermal exposure (temperature exposure in the absence of mechanical stress) and under biaxial loading at a constant intensity of external stresses was performed. It is shown that under uniform tension in a plane stress state, the relaxation of residual stresses slows down, and under compression, the relaxation rate increases compared to the case of thermal exposure.

In this study, the Al₂O₃-H₂O nanofluid flow through a duct with a square cross section under a constant heat flux is simulated using a single-phase model. According to the chosen values of the Reynolds and modified Richardson numbers, this flow is laminar, and it is considered in mixed convection. The dynamic and thermal parameters of this flow are determined numerically by using the CFD-Fluent software based on the finite volume method by introducing the Boussinesq approximation. The analysis is carried out for Reynolds numbers ranging from 100 to 1000 and modified Richardson numbers equal to 0.1 and 0.5. The results obtained show that gravitational forces generate two thermo-convective cells in each cross section along the channel, and asymmetric temperature and velocity profiles are formed. The effects of the volume fraction of nanoparticles, Reynolds number, and modified Richardson number on the flow structure, Nusselt number, and pressure drop are analyzed. With the use of nanofluids, the Nusselt number increases, which ensures heat transfer enhancement. Finally, a correlation is proposed for the Nusselt number as a function of the nanoparticle volume fraction, which can be used for heat transfer predictions.

Explosive welding is a solid-state joining procedure that involves the propulsion of a flyer plate by the explosion of an explosive to produce welds of two or more similar or dissimilar materials. The development of molten intermetallic compounds at the interface degrades the mechanical properties of welded alloys. However, the employment of an interlayer in explosive welding significantly increases the kinetic energy dissipation and prevents the formation of molten intermetallic compounds at the interface, thereby increasing the bonding strength. Earlier researchers employed interlayers having different values of the thickness, yield strength, ductility, and density. The influence of the interlayer on the microstructure and mechanical properties of explosively welded similar and dissimilar alloys is thoroughly reviewed in this study. In addition, the significance of explosive welding in different environments, such as helium, underwater, and gelatin media, is also summarized. Correspondingly, future advancements in joining of materials through explosive welding are forecasted.

In connection with the taxonomic revision of the species of the genus Lappula Moench in the flora of Kazakhstan and Uzbekistan, a related group of L. subcaespitosa from the series Tianschanicae Popov ex Ovczinnikova of the section Microcarpae (Popov) Ovczinnikova was identified, which requires critical study. Analysis of all herbarium materials stored in LE, MW, TASH, AA, NSK, TK, KUZ Herbaria, including type specimens and new collections from the South Kazakhstan region of Kazakhstan, from the territory of the Sairam-Ugam National Park, as well as from the Boraldai Mountains included into the system of ridges of the Syrdarya Karatau, made it possible to determine the diagnostic and ecological features, as well as the area of distribution of L. subcaespitosa and L. nevskii Raenko, and also to describe the new species L. kuprijanovii Ovczinnikova for science. The absence of a holotype required the lectotyping of the name L. subcaespitosa.

The history of the taxonomic study of species of the genus Galium L. (Rubiaceae) in Asian Russia is considered. Systems of the genus and the position of species within these systems are discussed. The main systems are A.P. de Candolle, E.G. Pobedimova, A.G. Elenevsky et al. It was revealed that C. Linnaei described the genus Galium in “Species Plantarum”. The first system of the genus was developed by A.P. de Candolle, in which he distinguished 13 sections. The system of the genus, proposed by E.G. Pobedimova, includes 93 species, united in 11 sections, 5 subsections and 19 series. E.G. Elenevsky et al. revised the volume of a number of sections, described 3 new sections, and one section was given as a new combination. Their system of the genus Galium contains 46 species, which are distributed in 21 sections. G. Gmelin, C. F. Ledebour, N.S. Turczaninow, K.J. Maximowicz, V.L. Komarov, P.N. Krylov, N.N. Tsvelev. It is shown that regional floristic summaries have expanded knowledge about the morphology, geography and ecology of species of the genus Galium in Asian Russia.

A review of Viscum coloratum (Kom.) Nakai (Santalaceae) about its chemical composition, biological characteristics and pharmacology has been made. It was shown, that along the rich set of secondary metabolites among phenolic and others compounds, V. coloratum accumulates N-containing - lectins, viscotoxins, defensins and ect., and accumulates particular diarylheptanoids, lignans, chromones, which were not characteristic for other plants. Structural formulas of the majority of components are given in this paper. Collected information about biological activity of the extracts and individual components, confirmed expediency of using V. coloratum, in standart practice medicine.

The results of studying Hemerocallis minor during introduction in the forest-steppe conditions of the Novosibirsk region are presented. The features of seasonal development taking into account the temperature factor are considered. It was found that in the conditions of the forest-steppe zone of Western Siberia, the flowering of H. minor occurred at the sum of positive temperatures of 703.5-828.0 °C. Information about the organogenesis of monocarpic shoot is given. It is shown that the generative shoot is laid in the year preceding flowering. In the pre-winter period, its condition is characteristic of the sixth-seventh stages of organogenesis. The life form of H. minor in the conditions of introduction belongs to short-rooted perennials, with a monopodially increasing axial shoot system of the rosette type and erect elongated generative shoots. The adventitious root system is formed by two types of roots: feeding and storing. The morphological description of seeds, their germination and productivity is presented. It is noted that seeds after 25-day stratification at a temperature of 5-6 °C germinate faster than without stratification. It was found that the coefficient of seed productivity had a value of 47.7 %. Xeromesophytic features in the anatomical structure of the leaf blade are revealed. Ulicny apparatus tetrazine type. The number of stomata on the lower epidermis of the leaf is 1.5 times greater than on the upper one. A well - developed mechanical tissue, the conducting sclerenchyma and the xylem and phloem.

Syntaxonomy of zonal tundra vegetation is still not clear and far from unambiguous explanation. This article presents the results of floristic classification of zonal tundra communities in the Asian Arctic tundras. These communities, widespread under automorphic conditions on the watersheds are included in a new alliance Salici pulchrae-Caricion lugentis, described from the Far North-East of Russia. This unit includes 7 associations and 2 subassotiations, based on relevees ftom Magadan region, Chukotka and Sakha (Yakutia) Republic. The classification is conducted by the Braun-Blanquet method (Westhoff, Maarel, 1978; Mirkin,1989; Dierschke, 1994; Mirkin et al., 2000). Diagnostic species of the alliance include hypoarctic dwarfshrubs, tundra graminoids and some mosses and lichens, common for southern tundra subzone, typical and subarctic tundras of the Asian sector of Russian Arctic - Aulacomnium palustre, Aulacomnium turgidum, Betula exilis, Carex lugens, Eriophorum vaginatum, Flavocetraria cucullata, Ledum decumbens, Salix pulchra, Vaccinium uliginosum, Dicranum elongatum, Dryas punctata, Hylocomium splendens, Ptilidium ciliare, Tomentypnum nitens, Vaccinium vitis-idaea. Geographically new alliance coveres the territory of boreal highlands of Czersky and Kolymsky mountain ranges, tundra zone of Sakha Republic and Chukotka to the north and east from treeline. The alliance Salici pulchrae-Caricion lugentis is not yet disposed in some higher units - order and class. It has been suggested that for higher syntaxa Carici arctisibiricae-Hylocomietea alaskani Matveyeva et Lavrinenko 2016 cl. prov. is proposed (Lavrinenko et al., 2016). To determine the syntaxonomical status of the class and proposed order new relevees from this remote territory is expected.