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In recent decades, the water management and environmental situation in the Ural River basin was rather tense. This is true for its parts both in the Russian Federation, where the major portion of water resources is formed, and in Kazakhstan. The quantitative and qualitative depletion of water resources in the following years and the abrupt deterioration of the environmental conditions in many parts of the river make it necessary to carry out a large-scale study of the problems at a geosystem level. The article presents the results of studying small rivers in the part of the Ural River basin within the Russian Federation territory, where river runoff and environmental conditions vary under the effect of a combination of natural and anthropogenic factors. The methodological base of the study is the geosystem approach and the basin principle, which enable a comprehensive study of the effect of a combination of natural and anthropogenic factors on the formation of variations of quantitative and qualitative characteristics of watercourses and the ecological conditions in them. The methods of study include generalization and analysis of the data of earlier studies, field studies and observations, sampling water and bottom sediments, zoning of the area under study by the types and levels of anthropogenic load, determination of the character of pollution of watercourses and changes in the ecological conditions in them, depending on the effect of specific types of economic activity. The study revealed specific features of the effect of human economic activity on small rivers and the natural complexes in their drainage areas. The characteristics of the space and time variations in the factors that cause changes in the slope and river runoff are determined. The features of the effect of anthropogenic factors on water quality in water objects and the ecological conditions in them are studied; proposals for ecological rehabilitation, preservation, and recovery of small rivers—tributaries of different orders of the transboundary Ural River—are substantiated. [ABSTRACT FROM AUTHOR]

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

Methods for assessing the current state and forecasting critical events are developed in order to reduce the stress load on the pilot of an aircraft. These methods are based on the energy approach to flight control. Algorithms for forecasting the possibility of safe takeoff in the presence of high-rise obstacles on the trajectory are obtained. Forecast correction algorithms are introduced. Algorithms for calculating the braking distance depending on the runway condition are found in the modes of landing or emergency braking at takeoff. Some ways to correct forecasts considering the sequence and operation time of all braking devices are proposed. Model tests are carried out for the algorithms in the entire range of operating conditions. [ABSTRACT FROM AUTHOR]

The heat-resistant Ti–Al–Zr–Si alloys (base Ti–(6–7)Al–(2–3) Zr–(1–1.5)Si and additionally alloyed Ti–(6–7)Al–(3–5)Zr–(1–1.5)Si–(2–4)Sn), obtained by electron beam smelting were studied. Deformation was carried out in the β- or upper part of the (α+β)-area by means of forging and rolling into a strip. The base alloy was subjected to rolling in the upper part of the α+β-area, and the fine-grained uniform structure with a grain size of 10–20 μm was obtained. Internal stresses and defective substructure of the deformed alloy intensify the decomposition of the solid solution and promote the formation of evenly distributed dispersed silicides, which allows obtaining high strength and heat resistance characteristics. Tensile tests at 20; 650 and 700°C of the Ti–(6–7)Al–(2–3)Zr–(1–1.5)Si alloy samples after deformation and annealing also showed a rather high level of the tensile strength and yield strength. After 20 h exposure at the operating temperature of 700°C, the structure becomes more equilibrium, due to which the strength of the deformed alloy decreases, and the relative elongation increases. Additional alloying of the base alloy with zirconium and tin slightly increases plasticity and decreases heat-resistant properties. [ABSTRACT FROM AUTHOR]

The article reflects the problem of graphite-containing sludge accumulated, as deposit, in technological systems during the operation of uranium-graphite reactors. Technical and methodological approaches to the performance of work on the survey of reservoirs are presented, which made it possible to remotely select highly active samples of graphite-containing sludge from closed reservoirs located in radiation-hazardous rooms, and to estimate the volume, layer thickness, and surface profile of deposits. Methods are described, including radiochemical ones, used in the course of research to determine the radionuclide composition, activity levels, amounts of solid and liquid phases, moisture content, and mass loss on ignition. To predict the behavior of radionuclides sorbed on deposits, the selective desorption method was used to determine the water-soluble, ion-exchange, low-mobility, strongly bound, and strongly fixed forms of radionuclides in samples of graphite-containing sludge. The results obtained were used to assess nuclear and radiation safety, as well as to develop technological methods for handling graphite-containing sludge during the decommissioning of reservoirs. Proven approaches to survey and laboratory analysis of sediments can be used in the inspection of other similar reservoirs containing high-level deposits. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the role of pseudocontinuous arterial spin labeling perfusion (pCASL-perfusion) in preoperative assessment of cerebral glioma grades. The study group consisted of 253 patients, aged 7–78 years with supratentorial gliomas (65 low-grade gliomas (LGG), 188 high-grade gliomas (HGG)). We used 3D pCASL-perfusion for each patient in order to calculate the tumor blood flow (TBF). We obtained maximal tumor blood flow (maxTBF) in small regions of interest (30 ± 10 mm2) and then normalized absolute maximum tumor blood flow (nTBF) to that of the contralateral normal-appearing white matter of the centrum semiovale. MaxTBF and nTBF values significantly differed between HGG and LGG groups (p < 0.001), as well as between patient groups separated by the grades (grade II vs. grade III) (p < 0.001). Moreover, we performed ROC-analysis which demonstrated high sensitivity and specificity in differentiating between HGG and LGG. We found significant differences for maxTBF and nTBF between grade III and IV gliomas, however, ROC-analysis showed low sensitivity and specificity. We did not observe a significant difference in TBF for astrocytomas and oligodendrogliomas. Our study demonstrates that 3D pCASL-perfusion as an effective diagnostic tool for preoperative differentiation of glioma grades. [ABSTRACT FROM AUTHOR]

The growing relevance of the use of unmanned aerial vehicles (UAVs) for studying turbulence in the atmospheric boundary layer (ABL) is associated with the need to obtain new observational data at different heights in the boundary layer, as well as over heterogeneous landscapes. Such new data is needed for developing turbulence models for spatially inhomogeneous and unsteady conditions. This paper describes the new Tsimlyanin UAV and its meteorological payload, developed specifically for studying the turbulent structure of the ABL. Tsimlyanin differs from similar vehicles by its hybrid scheme, which combines the possibility of vertical take-off and landing and horizontal flight in airplane mode. The meteorological payload includes specially designed measuring devices, namely, a multihole air pressure probe and a low-inertia resistance thermometer. Also, analog-to-digital converters for several sensors, as well as the onboard data-acquisition system, are newly developed. This paper presents the results of measurements carried out using the UAV during test flights in Tsimlyansk in August 2020. A good agreement between UAV observations with respect to vertical profiles of air temperature, wind speed and direction, dispersion of vertical speed with the data of observations of other complexes (acoustic anemometers, an automatic meteorological station, sodars, and a temperature profiler) was obtained. The results demonstrate the high potential of this UAV for studying turbulence in the ABL. [ABSTRACT FROM AUTHOR]

In this paper, a methodology to design algorithms for predicting the aircraft's braking distance is presented. An efficient predicting algorithm based on the energy approach to aircraft control is developed. A new forecast correction concept is proposed. With this concept, the predicting accuracy is improved, and the degree of confidence in the predicting results is increased. Statistical tests of the algorithms under different runaway conditions and different aircraft configurations are performed. The predicting reliability is proved. [ABSTRACT FROM AUTHOR]

Lignin valorization is strongly dependent on a right strategy for converting lignin into value-added products. Conversion of lignin into monomeric degradation products is one of the important avenues. In this study, chemical mechanisms and monomeric product compositions in hydrolysis (acidic and alkaline), hydrogenolysis, catalytic oxidation, electrochemical oxidation and reduction, photochemical and enzymatic degradation of native and technical lignins, and lignin model compounds are comparatively analyzed. The effect of the structure of a phenylpropane unit in lignin on the chemical reactivity of α-O-4 and β-O-4 bonds in cleavage reactions is also described. Published experimental data suggest some form of activation to be a necessary prerequisite for the splitting of a β-O-4 bond in all chemical reactions under consideration, the nature of which is dependent on the reagents and reaction conditions. Thus, in catalytic oxidation processes, a benzyl hydroxyl group is converted into carbonyl group at the first stage. Chemical transformation involving the α-position in a phenylpropane unit is a usual trigger of further lignin depolymerization. The yield of monomeric products of hydrogenolysis of native lignin is close to the theoretical one, reaching 23% in softwood and 51% in hardwood; in alkaline hydrolysis as well as oxygen and nitrobenzene oxidation of native lignin, the trend is the same that is explained in this study. On the other hand, the yield of monomeric products from isolated samples and technical lignins is much lower. A loss of arylether bonds in the process of lignin separation from wood and in wood pulping explains this difference. [ABSTRACT FROM AUTHOR]

A search for new anticonvulsants led to a series of 2-(4-oxo-2-thioxo-1,4-dihydro-3(2H)-quinazolinyl)- acetamides that were synthesized by reacting (4-oxo-2-thioxo-1,4-dihydro-3(2H)-quinazolinyl)acetic acid with the appropriate amines in the presence of N,N′-carbonyldiimidazole. The tested compounds showed weak and moderate anticonvulsant effects in a pentylenetetrazole-induced seizure model in mice. Several features of the structure—activity relationships are discussed. [ABSTRACT FROM AUTHOR]

High-purity fucoidan fractions were obtained from brown seaweeds Sargassum miyabei and S. oligocystum. Both first fractions were mannnogalactofucans; second, galactofucans. Fucoidans from S. miyabei contained acetyls. The isolated polysaccharides were not cytotoxic at concentrations up to 400 μg/mL. Formation and growth of colonies of HT-29 and HCT-116 cells were weakly inhibited by the tested fucoidans. Fucoidans SmiF2, SoF1, and SoF2 had the greatest anticancer effects against the DLD-1 cell line. [ABSTRACT FROM AUTHOR]

An assay method for the excipients (sucrose, phosphatidylcholine, and cholesterol) of liposomal medicinal formulations of the phthalocyanine photosensitizer lipophthalocyan by TLC with chromatodensitometry was validated. Coefficients of standard residual deviation for establishment of linearity were 3.48 for sucrose, 1.69 for phosphatidylcholine, and 1.36 for cholesterol. The coefficients of variation for determination of similarity and intermediate precision were less than 5%. The method was shown to be reliable over a wide range of conditions for the suitability of the system. [ABSTRACT FROM AUTHOR]

This is a review of historical and modern literature data on the structure versus properties of wood lignin in view of the concepts developed by the authors based on their own research. Changes in the structure of lignin and related changes in its chemical reactivity during alkaline wood pulping are assessed based on the comparison of the structures of lignin at three kinetically distinct stages of delignification: initial, bulk and final. Lignin gradually moves from a solid to a liquid phase during the pulping process; therefore, structures of native, dissolved and residual lignin are elucidated and compared. The emphasis is on changes in the molecular weight distribution and content of alkylarylether bonds, and functional groups, in particular phenolic hydroxyls. For comparison, splitting rates for α- and β-alkylarylether bonds in both phenolic and non-phenolic lignin model compounds are analyzed. Based on the comparative analysis of the experimental data, it is suggested that native lignin in wood consists mainly of three distinct fractions that are different in chemical reactivities of alkylarylether bonds. This phenomenon results in three kinetically distinct stages of the pulping process. Wood delignification is essentially a process of lignin functionalization followed by its dissolution. The functionalization, i.e., formation of additional functional groups in the macromolecule, continues until it reaches the level sufficient for lignin dissolution under chosen conditions, and then, delignification occurs. At the bulk stage of pulping, the rate of delignification is directly proportional to the degree of functionalization. The data characterizing the effect of redox reactions on the structure and chemical reactivity of lignin in alkali-anthraquinone pulping are analyzed in detail in view of their general importance for our understanding of the chemical reactivity of lignin. Results of polarographic studies of numerous representative lignin model compounds (> 70 samples) and lignin samples, including chemically changed lignins, are compiled, and a diagram of reduction potentials of polarographically active functional groups in lignin is drawn. From a comparison of redox properties of lignin and 32 pulping additives, criteria for selection of potential alkaline pulping catalysts are derived. Solubility belongs to basic properties of polymers, lignin included, and all methods of delignification of plant materials can be essentially reduced to solid polymer functionalization followed by its dissolution. Factors contributing to lignin solubility are analyzed, including such characteristics as molecular weight, temperature, liquid-solid ratio and ionic strength. Based on the analyzed data, a uniform scale of solubility for different lignin types is proposed, and formulae for calculating lignin solubility in alkaline media are derived. [ABSTRACT FROM AUTHOR]

The application of an ultrasound-assisted extraction method, combined with ion-exchange chromatography, has allowed separation of the total fucoidan fraction (F1) from the brown alga Fucus evanescens into two fractions, F2 and F3, in the ratio 1:0.2. The traditionally extracted F1 differs from F3 only by the acetate groups at C3 being somewhat predominant. F2 is described as having acetate groups located chaotically, and contains galactose and xylose residues, in addition to fucose. F3 consists of fucose residues acetylated almost exclusively at C3. Therefore, with ultrasound-assisted extraction from the brown alga Fucus evanescens, a new regular 1 → 3;1 → 4-α-L-fucan was obtained. It is sulphated at C2 and acetylated at C3 of the fucose residue and showed anticancer activity in vitro towards human colon carcinoma cells comparable to the total fraction F1. [ABSTRACT FROM AUTHOR]

The Cramer-Lundberg model is considered as a model of insurance company. Since it is impossible to obtain an explicit solution for the non-ruin probability function of insurance company for an arbitrary distribution of the values of insurance claims, the authors consider the problem of estimating the convergence of the original non-ruin probability to one that would be obtained by approximating the values of claim distribution function. [ABSTRACT FROM AUTHOR]

The 1→3;1→6- β-D-glucan chrysolaminaran with molecular weight 8.5 kDa and 3.6:1 ratio of 1→3:1→6 bonds was isolated from cultivated diatom alga Synedra acus and characterized. It was shown that the isolated chrysolaminaran inhibited growth and colony formation of human colon tumor cells. [ABSTRACT FROM AUTHOR]

Seasonal variations of the polysaccharide composition of the brown alga Costaria costata were studied. It was found that the alga synthesized in April-May a high-molecular-weight (200–800 kDa) low-sulfated heterofucan; in July, primarily a low-molecular-weight (20–300 kDa) sulfated and acetylated galactofucan. A small amount (<0.01% of total alga mass) of laminaran (1,3;1,6- β-D-glucan) was observed in mature alga. [ABSTRACT FROM AUTHOR]

The energy flows during vacuum arc remelting (VAR) of a 20-in.-diameter ingot of INCONEL 718 have been investigated experimentally, numerically, and theoretically, and the results are compared and discussed. The temperatures at a number of points on the outer surface of a VAR crucible were measured during a melt. A forward heat-flow model was constructed and the (initially unknown) interior heat flux distribution refined iteratively until the predicted crucible temperatures matched the measurements. The model included radial and vertical heat flow within the crucible and the development of a heated cooling water layer near the outer surface of the crucible. Significantly, it is shown that the temperature difference between the crucible outer surface and the bulk cooling water was not a linear function of the heat flux at the crucible inner surface. It is shown that results from the literature of plasma physics can be used to place bounds upon the partition of energy during VAR. These bounds are combined with the numerically-inferred power distribution within the crucible to estimate the position of the ingot top during the experiment and, hence, the overall energy partition. Side-arcing from the electrode to the crucible is shown to be predicted to transfer more energy to the crucible than has previously been expected. Time variation in the measured crucible outer surface temperature was also investigated as a means to estimate the ingot top position, and the results are compared with those from numerical modeling and plasma physics arguments. It is shown that the two methods are in fairly good agreement, but that they are in contrast with some aspects of results reported previously. [ABSTRACT FROM AUTHOR]

Non-steady-state ensemble arc behavior has been observed during the Vacuum Arc Remelting (VAR) of 508-mm-diameter ingots of INCONEL 718. The liquid metal flow in the melt pool of a 508-mm ingot during VAR has been simulated under two alternative sets of conditions: (1) a steady-state axisymmetrical arc distribution, as has been typically used in modeling work previously; and (b) a transient asymmetrical arc distribution. Due to the computational requirements, neither mass flux nor solidification were modeled; instead, the pool shape was fixed from measurements from a 508-mm-diameter ingot, and a constant pool wall temperature of 1609 K was used. The transient simulation assumed a localized Gaussian arc whose effective center was located at a distance of 0.1 m from the ingot centerline; this simulation rotated clockwise around the centerline with a period of 36 seconds. The steady-state model was simulated with axisymmetrical distributions of current and power input to the pool top surface calculated by time averaging the transient current and power inputs. The standard k- ε solver of ANSYS CFX 5.6 software was used for both simulations. The transient model results suggest that 5 seconds of asymmetrical arc behavior is enough to change the pool from steady state to transient and that, after 30 seconds, the flow is almost fully developed (at least to the accuracy of the model) and dominated by the Lorentz force. Aspects of the model results agree with key features of the melt pool observed during VAR. [ABSTRACT FROM AUTHOR]

Nutritional attractiveness of the brown alga Laminaria japonica for the sea urchin Strongylocentrotus intermedius was studied. The composition of L. japonica was analyzed after one and two years of its life under natural conditions, in its seedlings, and in the alga partially degraded by natural factors. Substances extracted with various solvents were tested for the presence of inhibitors and activators of 1,3-β- D-glucanase, a digestive enzyme of the sea urchin. Ethanolic extract of freshly harvested L. japonica was found to suppress the enzyme activity. Substances present in ethanolic extracts of the alga after one or two years of its life cycle and in the alga, partly degraded by natural factors, activated the sea urchin enzyme. This fact is in agreement with earlier natural observations concerning the nutritional attractiveness of such L. japonica samples for Strongylocentrotus intermedius. [ABSTRACT FROM AUTHOR]

The pTvalues of some acid-base indicators in surfactant-stabilized emulsions are found. Multiple linear regression equations are proposed to predict the protolytic properties of sulfophthalein reagents in emulsions based on various types of surfactants. The conditions are found for the alkalimetric determination of naproxen and ketoprofen with the end-point detection using thymol blue. [ABSTRACT FROM AUTHOR]

It was shown that hydrophobic organic salts can be determined by pseudo-single-phase ion-par titration in an oil-in-water emulsion stabilized with a nonionic surfactant. Conditions were proposed for determining anionic and cationic surfactants and some hydrophobic salt pharmaceuticals in an emulsion stabilized with Triton X-305 using molybdenum(VI)–Pyrogallol (Bromopyrogallol) Red complexes for the detection of the titration end-point. [ABSTRACT FROM AUTHOR]

Using the Euler approximations of solutions of abstract differential equations, we obtain new approximation formulas for C0-semigroups and evolution operators. [ABSTRACT FROM AUTHOR]

We construct a multidimensional generalized diffusion process with the drift coefficient that is the (generalized) derivative of a vector-valued measure satisfying an analog of the Hölder condition with respect to volume. We prove the existence and continuity of the density of transition probability of this process and obtain standard estimates for this density. We also prove that the trajectories of the process are solutions of a stochastic differential equation. [ABSTRACT FROM AUTHOR]

Results of an experimental study of supersonic flow around truncated cones with cone half‐angles of 20, 30, and 40°, performed at Mach numbers M = 2, 3, and 4 within the range of angles of attack up to 20°, are presented. A relationship is established between the emergence of an internal shock wave and the character of pressure distribution along the generatrix of the truncated cone. It is shown that the known boundaries of regimes obtained for axisymmetric flow around sharp and blunt cones can be used to predict flow regimes in the vertical plane of symmetry of the truncated cone at incidence. [ABSTRACT FROM AUTHOR]

Cultured ginseng cells (Panax ginseng C.A. Mey strain R-1) produce two proteins exhibiting RNase activity (Pg1 and Pg2), which, on the basis of their amino acid sequences, have been earlier referred to intracellular pathogenesis-related proteins. An immunoenzyme technique for estimation of these proteins was developed. A close correlation was found between the content of these proteins and the RNase activity of the cultured cells. Ethephon and jasmonic acid activated the RNase activity, ethephon being more efficient. Salicylic acid did not activate Pg1 and Pg2; high concentrations of salicylic acid suppressed the RNase activity of the culture. The protein kinase inhibitor, H-7, reduced the content and activity of RNases both in the presence and absence of ethephon. The results obtained permit a suggestion that ethylene and jasmonic acid signaling pathways, which include protein phosphorylation, are involved in the induction of PR-10 proteins. [ABSTRACT FROM AUTHOR]

The proton-donor properties of 1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid (indometacin) were studied in emulsions based on different surfactants and their mixtures. A procedure for the alkalimetric titration of indometacin with detecting the titration end-point in the presence of Cresol Red was developed using an emulsion based on dodecylpyridinium chloride. The conditions for determining indometacin in medicinal forms by pH-metric titration were selected. [ABSTRACT FROM AUTHOR]

It was shown that the acid number of oils and fats emulsified in aqueous solutions of surfactants can be determined by alkalimetry. Effective pK values of pure long-chain carboxylic acids and acids from some edible oils were determined in different surfactant emulsions. Effective pT values were found for some acid–base indicators in an emulsion stabilized with a mixture of dodecylpyridinium chloride and Triton X-100. Conditions were selected for the determination of the acid number of oils and fats in emulsions based on a mixture of cationic and nonionic surfactants by alkalimetry with the detection of the titration end-point by pH-metry and with the Cresol Red indicator. [ABSTRACT FROM AUTHOR]

Results of an experimental study of a supersonic flow around the leeward side of a delta wing are presented. The experiments are performed on three delta wings with leading–edge sweep angles χ = 68°, 73°, and 78° for Mach numbers M =2—4 and angles of attack α = 0—22°. Data on the structure and position of internal shock waves are obtained; the size and location of primary and secondary vortices are found. New regimes of the flow around a delta wing are identified. The chart of flow regimes around delta wings is refined and extended. [ABSTRACT FROM AUTHOR]

The leeside vortex structures on delta wings with sharp leading edges were studied for supersonic flow at the Institute of Theoretical and Applied Mechanics of the Russian Academy of Sciences in Novosibirsk. The experiments were carried out with three wings with sweep angles of χ=68°, 73°, and 78° and parabolic profiles in the 0.6 × 0.6 m2 test section of the blow-down wind tunnel T-313 of the institute. The test conditions were varied from Mach numbers M=2 to 4, unit Reynolds numbers from Rel=26 × 106 to 56 × 106 m−1, and angles of attack from α=0° to 22°. The results of the investigations revealed that for certain flow conditions shocks are formed above, below, and between the primary vortices. The experimental data were accurate enough to detect the onset of secondary and tertiary separation as well as other boundaries. The various flow regimes discussed in the literature were extended in several cases. The major findings are reported. [ABSTRACT FROM AUTHOR]

Twenty-five strains of epiphytic marine bacteria isolated from the brown algaeFucus evanescens andChorda filum and fifty-three bacteria isolated from the sea cucumberApostichopus japonicus were screened for fucoidanases using fucoidans prepared from the brown algaeF. evanescens, Laminaria cichorioides, andL japonica. Eighteen bacterial epiphytes and thirty-eight bacterial isolates from the sea cucumber were found to contain fucoidanases, which were able to hydrolyze either all of the fucoidans studied or some of them. Bacteria of the generaCytophaga andAlteromonas/Pseudoalteromonas exhibited the highest fucoidanase activities, which, however, did not exceed the activity of fucoidanases from the already known sources. [ABSTRACT FROM AUTHOR]

The bioequivalence of mefebut drug substance and its tablet dosage form was investigated by studying the main pharmacokinetic parameters and calculating the relative bioavailability. The results showed that mefebut circulated for up to 4 h in rabbit blood after peroral administration. The relative bioavailability was 97.4%. [ABSTRACT FROM AUTHOR]

The article presents a study on the structure of sulfated polysaccharides that is synthesized by Costaria costata brown algae. It says that the polysaccharides were separated at room temperature through acid extraction using fucoidan (F) and laminaran by chromatography. It also mentions that structure of monosaccharide from products of polysaccharides was determined through high performance liquid chromatography (HPLC) which reveals compositions of uronic acids, protein, and monomers.