40 research outputs found

    Fatigue behaviour of CG and UFG titanium: DIC and fractography studies

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    The manuscript is devoted to the investigation of fatigue behaviour of coursegrain (CG) and ultrafine-grain (UFG) titanium grade 2 by means of digital image correlation (DIC) and scanning electron microscopic fractography. The UFG state has been obtained utilizing severe plastic deformation technique. The results show that the high amount of defects (grain boundaries, dislocations, etc.) in UFG suppress plastic deformation and leads to earlier crack initiation, however at the macrocrack growth stage these impurities are obstacles for transgranular mechanism of fracture

    Medium-Early Spring Wheat Cultivars Depending on The Level of Mineral Nutrition in The Northern Forest-Steppe of The Tyumen Region

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    This article analyzes the results by the yield and grain quality of two spring wheat cultivars Tyumenskaya Yubileynaya and Tyumenocka, depending on the level of mineral nutrition in the forest-steppe zone of the Tyumen region. The length of the vegetation period corresponded to the climatic conditions of the forest-steppe zone of the Tyumen region. In the reference variant and the variant with 4 tons of NPK per hectare, it was 90 days, and in the variants with 4 and 6 t/ha, it was 92 days. In the reference variant, the average yield of the Tyumenskaya Yubileynaya cultivar over the three years was 3.31 t/ha, and that of the Tyumenocka cultivar — 2.93 t/ha. The introduction of mineral fertilizers for the planned yield of 4 t/ha allowed obtaining the yield for the Tyumenskaya Yubileynaya cultivar equal to 4.14 t/ha, which was by 0.83 t/ha more than in the reference variant. The Tyumenocka cultivar yielded 3.83 t/ha, which was by 0.90 t/ha higher than in the reference variant. Further increasing the dosages of mineral fertilizers to 5 t/ha allowed obtaining 4.73 – 4.72 t/ha for both cultivars, which was by 0.27 – 0.28 t/ha lower than planned yield. The content of gluten in the grain of cultivar Tyumenskaya Yubileynaya in the reference variant was 27.2 %, of the Tyumenocka cultivar — 24.2 %. In the variant with 4 tons of NPK per hectare, an increase in the content of gluten by 9.6 – 10.4 %, respectively, was noted. According to the economic calculations, the most favorable for spring wheat cultivation in the Tyumen region is the level of mineral fertilization equal to 5 tons of NPK per hectare

    Assessment of natural density of distribution for fish by the catches at light stations

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    Algorithm for calculation of illumination produced by shipboard lights at the sea surface and underwater is developed and implemented with Microsoft© Office Excel software. The surface illumination is calculated for the fishing vessel STR-420 with the light equipment for saury fishery. Irregularity of the lighting around the vessel is shown that depends on the lamps arrangement. Optimal scheme of the lamps arrangement is proposed for a new saury trap with the catch volume > 7000 m3. The optimal arrangement provides more regular lighting and therefore larger illuminated area for attraction of fish with positive phototaxis, as saury. Relationship between natural density of saury distribution and its catch per trap is determined for this trap

    Anchor system for installation of fishing gears on soft grounds

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    Mushroom anchors are proposed for positioning of vessels and fishing gears on soft grounds, as sands and silts. Designs of the anchors of original shape are presented. Their holding force is determined for certain navigational conditions, and the forces acting on a floating object are calculated for the cases of anchoring perpendicular and parallel to the water flow. Weight of the mushroom anchors necessary for anchoring of a floating object is calculated and scheme of the anchorage is presented for the depth 250 m. The mushroom anchors using for rescue operations in the Okhotsk Sea and for shrimp pot fishery in the Japan Sea is discussed, in particular the episode of positioning the vessel of deadweight 2433 t in conditions of 3-points roughness and the current velocity 2 knots at the sea surface and 4 knots at the sea bottom with using two stern and one bow mushroom anchors. Using of the compact mushroom anchor for shrimp pot fishery allows to reduce the traps moving along the bottom during their hauling. Possibly, the mushroom anchors could be used for other gears installation, as well, as stationary nets, crab traps, bottom longlines, etc

    Dimensional Transformation of Percolation Structure in Mixed-Matrix Membranes (MMMs)

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    A large number of studies of mixed-matrix membranes (MMMs) have confirmed the possibility of obtaining new materials with unique transport properties, including for solving specific problems in the separation of mixtures of liquids and gases. The choice of particles with a given affinity for the matrix and separable components allows researchers to adjust the selective properties of MMMs in a wide range, which changes the properties of MMMs in a wide range. However, even within the framework of the most complex percolation mechanism of the formation of the MMM structure, it is possible to explain only some of the observed effects. In particular, questions about the required particle concentration and fluctuation of properties in various MMM samples are still the subject of research. The results of the numerical modeling of such structures presented in this paper determined the possible causes of the observed deviations of the experimental results, for example, particle size dispersion, agglomeration, and interaction with the matrix. According to our research, the key factor that qualitatively changes the parameters of percolation structures is the ratio of the geometric dimensions of the system. We have confirmed in a wide range a significant change in the conditions of cluster formation and its power at different particle diameters and lengths (traditional parameters in percolation studies). But in our work, we additionally studied the effect on the cluster parameters of the interfacial layer and the anisotropy of the matrix (the transition from the cube to the film). The results obtained show that changing the parameters of the matrix–particle interaction affects agglomeration, and the degradation of the percolation structure is possible. That is, with an increase in concentration, the parameters of the percolation cluster, its power, and the probability of formation, may decrease. But even more negative changes in percolation structures are observed during the transition from a volumetric matrix to films. The anisotropy of space leads to the formation of percolation through the film in certain areas at low concentrations of particles. At the same time, in a significant part of the matrix, percolation between the film surfaces will be absent, and the effect of changing the properties of MMMs in the matrix as a whole decreases. Our study explains the observed instability of MMM properties at fixed concentrations and parameters of embedded particles, including the effect of reducing the influence of particles with increasing concentration

    Percolation Effects in Mixed Matrix Membranes with Embedded Carbon Nanotubes

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    Polymeric membranes with embedded nanoparticles, e.g., nanotubes, show a significant increase in permeability of the target component while maintaining selectivity. However, the question of the reasons for this behavior of the composite membrane has not been unequivocally answered to date. In the present work, based on experimental data on the permeability of polymer membranes based on Poly(vinyl trimethylsilane) (PVTMS) with embedded CNTs, an approach to explain the abnormal behavior of such composite membranes is proposed. The presented model considered the mass transfer of gases and liquids through polymeric membranes with embedded CNTs as a parallel transport of gases through the polymeric matrix and a “percolation” cluster—bound regions around the embedded CNTs. The proposed algorithm for modeling parameters of a percolation cluster of embedded tubular particles takes into account an agglomeration and makes it possible to describe the threshold increase and subsequent decrease permeability with increasing concentration of embedded particles. The numerical simulation of such structures showed: an increase in the particle length leads to a decrease in the percolation concentration in a matrix of finite size, the power of the percolation cluster decreases significantly, but the combination of these effects leads to a decrease in the influence of the introduced particles on the properties of the matrix in the vicinity of the percolation threshold; an increase in the concentration of embedded particles leads to an increase in the probability of the formation of agglomerates and the characteristic size of the elements that make up the percolation cluster, the influence of individual particles decreases and the characteristics of the percolation transition determine the ratio of the sizes of agglomerates and matrix; and an increase in the lateral linear dimensions of the matrix leads to a nonlinear decrease in the proportion of the matrix, which is affected by the introduced particles, and the transport characteristics of such MMMs deteriorate

    Fluorescence-Polarization-Based Assaying of Lysozyme with Chitooligosaccharide Tracers

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    Lysozyme is a well-known enzyme found in many biological fluids which plays an important role in the antibacterial protection of humans and animals. Lysozyme assays are used for the diagnosis of a number of diseases and utilized in immunohistochemistry, genetic and cellular engineering studies. The assaying methods are divided into two categories measuring either the concentration of lysozyme as a protein or its activity as an enzyme. While the first category of methods traditionally uses an enzyme-linked immunosorbent assay (ELISA), the methods for the determination of the enzymatic activity of lysozyme use either live bacteria, which is rather inconvenient, or natural peptidoglycans of high heterogeneity and variability, which leads to the low reproducibility of the assay results. In this work, we propose the use of a chemically synthesized substrate of a strictly defined structure to measure in a single experiment both the concentration of lysozyme as a protein and its enzymatic activity by means of the fluorescence polarization (FP) method. Chito-oligosaccharides of different chain lengths were fluorescently labeled and tested leading to the selection of the pentasaccharide as the optimal size tracer and the further optimization of the assay conditions for the accurate (detection limit 0.3 μM) and rapid (<30 min) determination of human lysozyme. The proposed protocol was applied to assay human lysozyme in tear samples and resulted in good correlation with the reference assay. The use of synthetic fluorescently labeled tracer, in contrast to natural peptidoglycan, in FP analysis allows for the development of a reproducible method for the determination of lysozyme activity

    Nuclear-matter radius studies from 58^{58}Ni(α, α) experiments at the GSI Experimental Storage Ring with the EXL facility

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    A novel method for measuring nuclear reactions in inverse kinematics with stored ion beams was successfully used to extract the nuclear-matter radius of Ni-58. The experiment was performed at the experimental heavy-ion storage ring at the GSI facility using a stored Ni-58 beam at energies of 100 and 150 MeV/u and an internal helium gas-jet target. Elastically scattered a-recoils at low momentum transfers were measured with an in-ring detector system compatible with ultrahigh vacuum. Experimental angular distributions were fitted using density-dependent optical model potentials within the eikonal approximation. This permitted the extraction of the point-matter root-mean-square radius of Ni-58 with an average value of 3.70(7) fm. Results from this work are in good agreement with several experiments performed in the past in normal kinematics. This pioneering experiment demonstrates a major breakthrough towards future investigations with far-from-stability stored beams using the present technique
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