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The use of dry methods of processing and beneficiation of mineral raw materials is one of the promising areas, as this approach to concentrate production is less energy-consuming, less labor-intensive, and economically beneficial. The paper presents experimental studies on preliminary dry separation of Arkachan deposit ores to determine the quality of beneficiation of the separation products. The studies on dressability were carried out on pilot plants for dry ore processing and beneficiation: combined impact crusher DKD-300, centrifugal mill TsMVU-800, pneumatic separator POS-2000. Processing of the obtained separation products by pneumatic separation and screening according to the sequential flow chart of crushing and grinding was carried out in laboratory conditions at a gravity concentration table SKO-0.5. The GRG test was performed at an ITOMAK-0.1 centrifugal concentrator using a sequential grinding circuit. The GRG test showed that for more efficient gravity separation of gold, up to total gold recovery of 73.91%, the degree of grinding up to 80% passing 0.071 mm was required, allowing obtaining a gravity concentrate graded at 70.28 g/t gold.

Hydrogen can become a prevalent renewable fuel in the future green economy, but technical and economic hurdles associated with handling hydrogen must be overcome. To store and transport hydrogen in an energy-dense liquid form, very cold temperatures, around 20 K, are required. Evaporation affects the achievable mass flow rate during the high-speed transfer of hydrogen at large pressure differentials, and accurate prediction of this process is important for the practical design of hydrogen transfer systems. Computational fluid dynamics modeling of two-phase hydrogen flow is carried out in the present study using the volume-of-fluid method and the Lee relaxation model for the phase change. Suitable values of the relaxation time parameter are determined by comparing numerical results with test data for high-speed two-phase hydrogen flows in a configuration involving a tube with sudden expansion, which is common in practical systems. Simulations using a variable outlet pressure are conducted to demonstrate the dependence of flow rates on the driving pressure differential, including the attainment of the critical flow regime. Also shown are computational results for flows with various inlet conditions and a fixed outlet state. Field distributions of the pressure, velocity, and vapor fractions are presented for several flow regimes.

Introduction. Desarterization of hemorrhoidal arteries with mucopexia, a pathogenetically caused minimally invasive operation, is more often performed in stationary conditions under regional or general anesthesia. Aim. To study the results of desarterization of hemorrhoidal arteries in patients with hemorrhoids operated on an outpatient basis under local anesthesia.Materials and methods. 459 patients with chronic hemorrhoids of stage 2–4 with varying degrees of node prolapse under local infiltration anesthesia with Ultracaine were operated on by one surgeon. The duration of the intervention, the intensity of the pain syndrome, and the complications of treatment were studied. Results. The median duration of the operation is 25 minutes, the intensity of pain during the operation on a 10-point scale is 2 points, on the 3rd day of the postoperative period-2 points. Complications occurred in 6 (1.3%) people, in the 1st urinary retention, paraproctitis, and in the 4th – bleeding. Discussion. The obtained results of a longer procedure in patients with stage II hemorrhoids are associated with the training period. The intensity of pain during the HAL-RAR procedure performed under local anesthesia, including in patients of stage III-IV and IV, was acceptable and was tolerated by patients satisfactorily. The structure of the complications that have arisen is limited by a narrow range of pathology: bleeding, acute urinary retention, paraproctitis. Conclusion. Hemorrhoidal artery desarterization is an effective method of treating patients with chronic hemorrhoids on an outpatient basis: low duration ofsurgery, low frequency of complications. Local anesthesia during the ligation of hemorrhoidal arteries with mucopexia provides adequate anesthesia, patients tolerate the procedure and pain in the postoperative period, regardless of the stage of the disease, therefore, this method of treatment is advisable to use in outpatient practice.

A systematic study of extraction systems for the separation of f-elements using the tetradentate N,O-donor diamide of 1,10-phenanthroline-2,9-dicarboxylic acid (L) in various molecular and ionic solvents was performed. It was demonstrated that the nature of a diluent has a significant impact on solvent extraction of Am(III) and Ln(III) and the stoichiometry of formed complexes with f-elements. The mechanism of complexation and forms of complexes in different diluents were investigated by radiometric methods, UV-vis titration, and XRD.

Future thermoacoustic cryocoolers employing hydrogen as a working fluid can reduce reliance on helium and improve hydrogen liquefaction processes. Traditional thermoacoustic modeling methods often assume ideal-gas thermophysical properties and neglect finite-amplitude effects. However, these assumptions are no longer valid for hydrogen near saturated states. In this study, a comparison between the results of computational fluid dynamics simulations using actual hydrogen properties and a low-amplitude, ideal-gas thermoacoustic theory was carried out in a canonical plate-based stack configuration at a mean pressure of 5 bar. It was found that the simplified analytical theory significantly underpredicts the cooling power of hydrogen-filled thermoacoustic setups, especially at lower temperatures in high-amplitude, traveling-wave arrangements. In addition, a thermoacoustic prime mover was modeled at higher temperatures, demonstrating very close agreement with the ideal-gas-based theory. The CFD approach is recommended for the design of future hydrogen-based cryocoolers at temperatures below 80 K.

Hydrogen represents a promising renewable fuel, and its broad application can lead to drastic reductions in greenhouse gas emissions. Keeping hydrogen in liquid form helps achieve high energy density, but also requires cryogenic conditions for storage as hydrogen evaporates at temperatures of about 20 K, which can lead to a large pressure build-up in the tank. This paper addresses the unsteady thermal modeling of cryogenic tanks with liquid hydrogen. Considering the liquid and vapor phases in the tank as two nodes with averaged properties, a lumped-element method of low computational cost is developed and used for simulating two regimes: self-pressurization (also known as autogenous pressurization, or pressure build-up in the closed tank due to external heat leaks) and constant-pressure venting (when some hydrogen is let out of the tank to maintain pressure at a fixed level). The model compares favorably (within several percent for pressure) to experimental observations for autogenous pressurization in a NASA liquid hydrogen tank. The two processes of interest in this study are numerically investigated in tanks of similar shapes but different sizes ranging from about 2 to 1200 m3. Pressure and temperature growth rates are characterized in closed tanks, where the interfacial mass transfer manifests initial condensation followed by more pronounced evaporation. In tanks where pressure is kept fixed by venting some hydrogen from the vapor domain of the tank, the initial venting rate significantly exceeds evaporation rate, but after a settling period, magnitudes of both rates approach each other and continue evolving at a slower pace. The largest tank demonstrates a six-times-lower pressure rise than the smallest tank over a 100 h period. The relative boil-off losses in continuously vented tanks are found to be approximately proportional to the inverse of the tank diameter, thus generally following simple Galilean scaling with a few percent deviation due to scale effects. The model developed in this work is flexible for analyzing a variety of processes in liquid hydrogen storage systems, raising efficiencies, which is critically important for a future economy based on renewable energy.

With the accelerating development of liquid-hydrogen storage facilities, the problem of boil-off hydrogen losses becomes very important. A promising method to reduce these losses is to utilize the endothermic para-orthohydrogen conversion of vented hydrogen, which can effectively decrease heat loads on a hydrogen tank. To model such a process, a hybrid computational model has been developed, based on the application of computational fluid dynamics for an ullage space, where knowledge of thermal stratification is important, and reduced-order models for other system elements. The simulation results for a spheroidal tank in selected conditions indicated a 10–25% reduction of boil-off losses due to cooling produced by vented hydrogen undergoing para-ortho-conversion.

The article presents the results of research on the development of processes and equipment for ore preparation and pneumatic dry beneficiation of mineral ores. The methods of crushing and grinding before enrichment of minerals have been considered, dry enrichment of geomaterials is investigated. Highly efficient prototypes of beneficiation equipment are developed and tested: crushers of multiple dynamic impact RD-MDV-900, DKD-300, centrifugal grinders CMVU-800 and VCI-12, pneumatic separator POS-2000. Fundamental designs are created, and a number of new ore preparation and pneumatic beneficiation instruments are being designed. The efficiency of approbation of an autonomous dry beneficiation complex with new safe environmental standards for the processing of gold-bearing ores, which makes it possible to fully release and extract free gold with a particle size from 10,000 to 100 µm, is shown. The introduction of the dry beneficiation method is very promising for the mining industry. It will allow to reduce capital costs for the construction of stationary beneficiation plants, completely or partially withdraw from the use of process water, the construction of a water supply system, a traditional tailing dam, etc.

To examine the scope of the abnormal aryl strengthening effect (an increase in the extraction of metal ions when an aromatic substituent is introduced into the amide group) on f-metal extraction, a series of tetradentate diamide-type extragents bearing electron-withdrawing pyridine rings in amide moieties of the molecules were tested. The solvent extraction of Am(III)/Eu(III) pairs was investigated under various conditions, the solution chemistry of the lanthanide-extragents systems was studied, and the bonding constants were calculated for complexes of Eu(III) and Tb(III) ions with diamides. The photophysical properties of chemically synthesized ligand/metal (LM) complexes with various LM compositions were additionally studied in depth. The replacement of a phenyl ring by a pyridine one led to a critical reduction in metal affinity, showing the major contribution of electronic nature to the abnormal aryl strengthening effect. However, the pyridine group in the amide side chain provided additional coordination positions for metal ion binding; corresponding complexes with LM2 composition were detected in the system and their stability was calculated. Due to the low stability of the corresponding LM2 complexes, chemical synthesis of the complexes led to the formation of only one metal-containing species with LM composition. The luminescence spectra of europium and terbium complexes of the LM composition were studied. Differences were discovered in the luminescence excitation spectra of europium and terbium complexes with the same ligand. The luminescence quantum yields and luminescence lifetimes of solutions of europium and terbium complexes were determined.

A reaction of acyl chlorides derived from 1,10-phenanthroline-2,9-dicarboxylic acids with piperazine allows the preparation of the corresponding 24-membered macrocycles in good yield. The structural and spectral properties of these new macrocyclic ligands were thoroughly investigated, revealing promising coordination properties towards f-elements (Am, Eu). It was shown that the prepared ligands can be used for selective extraction of Am(III) from alkaline–carbonate media in presence of Eu(III) with an SFAm/Eu up to 40. Their extraction efficiency is higher than calixarene-type extraction of the Am(III) and Eu(III) pair. Composition of macrocycle–metal complex with Eu(III) was investigated by luminescence and UV-vis spectroscopy. The possibility of such ligands to form complexes of L:Eu = 1:2 stoichiometry is revealed.

Background. The tolerance of colon cleansing by Fortrans is associated with a number of negative factors. This determines patient compliance and quality of bowel preparation. The relevance of this issue is increasing due to the prevalence of this method in the diagnosis and treatment of colon pathology.The aim of the study was to investigate tolerance to Fortrans in colon preparation for colonoscopy and factors affecting comfort.Materials and methods. Before colonoscopy, a questionnaire method was used to study 84 patients who underwent colon preparation with Fortrans. Patient satisfaction with the preparation was evaluated on the visual analogue scale (VAS).Results. 45 (52.4%) people were satisfied with comfort of the preparation and rated its level 0–2 points on the VAS. 39 (47.6%) patients were not satisfied with the preparation, a discomfort level of 3–10 points was estimated. Factors affecting patient tolerance of Fortrans administration were determined.Conclusion. Satisfactory tolerance of the colon preparation by Fortrans is observed in half of the patients, which depends on their psychological state and expectations of the preparation comfort. The intolerance predictors to the colon preparation are negative side effects of Fortrans, which are largely leveled by the use of the split mode, as well as incorrigible factors: higher education, repeated colonoscopy, history of constipation.

Three pyrrolidine-derived phenanthroline diamides were studied as ligands for lutetium trinitrate. The structural features of the complexes have been studied using various spectral methods and X-ray. The presence of halogen atoms in the structure of phenanthroline ligands has a significant impact on both the coordination number of lutetium and the number of solvate water molecules in the internal coordination sphere. The stability constants of complexes with La(NO3)3, Nd(NO3)3, Eu(NO3)3, and Lu(NO3)3 were measured to demonstrate higher efficiency of fluorinated ligands. NMR titration was performed for this ligand, and it was found that complexation with lutetium leads to an approximately 13 ppm shift of the corresponding signal in the 19F NMR spectrum. The possibility of formation of a polymeric oxo-complex of this ligand with lutetium nitrate was demonstrated. Experiments on the liquid–liquid extraction of Am(III) and Ln(III) nitrates were carried out to demonstrate advantageous features of chlorinated and fluorinated pyrrolidine diamides.

Injecting air under hulls of marine vessels can lead to reduction of their hydrodynamic resistance. Since experimental development of air-assisted hulls usually requires a large number of tests, numerical simulations of air-ventilated water flows can potentially accelerate the design process. In this study, computational modeling has been carried out for the previously tested simplified hull form with an air cavity formed behind a step. To achieve proper agreement with experimental results, it is established that a sufficiently fine numerical mesh needs to be generated at the cavity re-attachment to the hull and the sharpening treatment of the air-water interface must be included. It is also shown how the cavity length can be manipulated by changing inclination of the cavity-originating step. Keywords: Drag reduction, Air-cavity hull, Two-phase flow, Computational fluid dynamics, Validation and verification

Hybrid donor extractants are a promising class of compounds for the separation of trivalent actinides and lanthanides. In this paper, we present a new ligand from the bipyridyl-dicarboxylic acid diamide family—N,N’-diethyl-N,N’-bis(2,4,5-trimethylphenyl)-[2,2’-bipyridine]-6,6’-dicarboxamide. The synthesis of N-ethyl-2,4,5-trimethylaniline from pseudocumene by selective acetylation is presented. The target ligand was obtained using this aminylene. Chemical synthesis of its complexes with Ln(NO3)3 and their spectroscopic analysis showed that the structure of the complexes is near to the corresponding structures of well-known di-methylated dianilides. A series of studies on the photophysical, complexing, and extraction properties of this ligand and its complexes were carried out. It was shown that the extraction system based on this ligand can selectively isolate americium from the solution of high-level waste imitator.

The fact of the fracture of the extraction curve of lanthanides by 1,10-phenanthroline-2,9-diamides is explained in terms of the structure of complexes, solvent extraction data and quantum chemical calculations. The solvent extraction proceeds in two competing directions: in the form of neutral complexes LLn(NO3)3 and in the form of tight ion pairs {[LLn(NO3)2 H2O]+ (NO3−).

Recent changes of the main oceanographic, chemical, and biological parameters of the Okhotsk Sea ecosystem are considered briefly for the last decades (2000–2010s), mostly on the data obtained in marine expeditions conducted by Pacific Fish. Res. Center (TINRO) annually. Since the mid-2000s, anomalous oceanographic conditions were formed there with prevailing heightened temperature in all layers of the sea and lowered ice cover caused by changes in the atmosphere circulation with northward shift of cyclones tracks in winter and weakening of winter monsoon. The ice cover was below the normal value every year since 2004. In the warmer winter conditions, producing of the high-density water on the northern shelf decreased from 3.2–7.8 . 103 km3 in 1998–2002 to 1.2 . 103 km3 on average in 2004–2015, and the water with density sq > 26.8 was not formed at all in 2007–2009, 2011, and 2014–2015. As the result, winter convection, including the slope convection, became weaker and shallower and ventilated worse the water column, so dissolved oxygen content decreased in the lower portion of the intermediate layer, usually ventilated by slope convection. For the core of the intermediate layer (isopycnal surface 27.0 σθ), positive trend of temperature is estimated as +0.04…+0.16 o/decade, by areas, while the trend of dissolved oxygen content is negative: –0.07…–0.14 mL/L.decade, by areas. From the other hand, spring phytoplankton bloom became less intensive, presumably because of poorer upward flux of nutrients in conditions of weaker vertical mixing, and zooplankton biomass decreased, particularly for phytophages. However, these changes did not cause significant response in fluctuations of stocks for the main commercial fish and crab species. The largest stock of walleye pollock had cyclic fluctuations driven mostly by intra-population regulations, the stocks of pacific herring were rather stable, and the stocks of deep-water fish species, as flounders and halibuts had a slight tendency to growth, possibly because of better conditions for reproduction. Indeed, the densest aggregations of greenland halibut shifted from the depth of 600–700 m to 500–600 m that may be caused by de-oxygenizing of the lower portion of the intermediate layer. Crabs abundance also had positive dynamics obviously because of the effect of protective measures for red king crab in the 2009–2012, though its biomass continued to grow even after restoring the commercial landings. There is concluded that recent changes in the macroecosystem of the Okhotsk Sea correspond to the conception of the sub-polar ecosystems transformation under climate warming toward decreasing of their productivity and increasing of their functioning efficiency that was proposed earlier for the Japan Sea. Thus, from position of commercial exploitation of marine biological resources, the modern reconstruction of the Okhotsk Sea ecosystem under the climate change impact could be considered as a positive process.

The regularities of differences are identified and the prospects marked for the use of extremely high frequency to detail representations about the features of the spectral characteristics of the tumor and non-tumor tissues.

The first examples of 1,10-phenanthroline-2,9-diamides bearing CF3-groups on the side amide substituents were synthesized. Due to stereoisomerism and amide rotation, such complexes have complicated behavior in solutions. Using advanced NMR techniques and X-ray analysis, their structures were completely elucidated. The possibility of the formation of complex compounds with lanthanoids nitrates was shown, and the constants of their stability are quantified. The results obtained are explained in terms of quantum-chemical calculations.

Habitat conditions, as qualitative and quantitative composition of aquatic vegetation and oceanographic factors, are compared for six populations of sea urchin Strongylocentrotus intermedius with different growth rate and mean size of individuals. The highest growth rate is observed in the areas between Cape Sosunov and Plitniak Bay, between Oprichnik Bay and Cape Grozny, and between Cape Lisuchenko and Kreiser Rock Island; all these areas are distinguished by high density and species diversity of macrophytes. On the contrary, the growth rate is the lowest at Cape Yuzhny where the vegetation is less abundant. All populations of slow-growing sea urchins inhabit the areas exposed to wave action that usually forms flat rocky platforms: at Cape Yuzhny, at Cape Nadezhda, and between the Yezhovaya Bay and Cape Khitrovo. However, density of sea urchin populations in these areas is higher (on average from 9.8 to 20.8 ind./m2) than in the areas with relatively high growth rate (from 0.16 to 7.20 ind./m2). Any signifcant correlation between the water temperature and mean size of sea urchins, by ages, is not detected.

Hydrodynamics of planing hulls is affected by proximity to the seabed floor in shallow waters. In this study, a three-dimensional steady linearized model based on the potential theory is applied to model flat planing surfaces at finite water depth and finite Froude numbers. Modeling results for shallow waters agree with experimental data in the subcritical and supercritical regimes sufficiently far from the critical speed that corresponds to the depth Froude number of unity. At the critical speed, nonlinear and unsteady effects become important, and a different modeling approach is required. Keywords: Shallow-water effects, Planing hulls, Potential flow modeling

Data of long-term observations on the cold intrusions in the warm intermediate layer of the Okhotsk Sea are overviewed, considering these intrusions as fresh portions of the Intermediate water of local origin. They are formed in the process of the high-density Bottom Shelf water cascading from the northwestern shelf, mainly in the submarine canyon at northwestern Sakhalin. Transport of these new-formed portions is traced in the flows of cyclonic circulation of the Okhotsk Sea waters from the area of their origin to the southern Kuril Straits, that takes from 2 to 6 years. Similar intrusions are found in the Pacific, mainly at southern Kuril Islands, where they penetrate presumably through the Vries and Bussol Straits. Year-to-year variability of the Bottom Shelf water and the new-formed Intermediate water properties are analyzed in dependence on external factors. There is determined that the volume and density of the Bottom Shelf water depend on winter severity that could be quantitatively explained by the ice cover; all these parameters decrease recently. Salinity of the new-formed Intermediate water has similar changes. Besides, tidal mixing influences on its salinity, in particularly at the Kuril Straits, so the tidal 18.6-year cycle is presented in the salinity variations. On the contrary, variations of the minimal temperature in the cold-water lenses of the fresh Intermediate water of local origin do not correlate with the changes in their production because of auto-compensatory effect for temperature in the process of its cascading to different depths. The same effect is obviously applied to dissolved oxygen, that’s why the oxygen content in the upper intermediate layer at the area of cascading is rather stable and doesn’t correlate with the ice cover changes. However, ventilation of the medium and deeper parts of the intermediate layer decreases on the background of recent lowering of the Intermediate water producing, in particularly the production of the water with σq ≥ 26.8. On a distance from the area of cascading, the tendency to deoxygenizing spreads over the whole intermediate layer of the Okhotsk Sea.

Modern structure–property models are widely used in chemistry; however, in many cases, they are still a kind of a “black box” where there is no clear path from molecule structure to target property. Here we present an example of deep learning usage not only to build a model but also to determine key structural fragments of ligands influencing metal complexation. We have a series of chemically similar lanthanide ions, and we have collected data on complexes’ stability, built models, predicting stability constants and decoded the models to obtain key fragments responsible for complexation efficiency. The results are in good correlation with the experimental ones, as well as modern theories of complexation. It was shown that the main influence on the constants had a mutual location of the binding centers.

Asymmetric planing hulls are often used on high-speed catamarans. In this study, a linearized potential-flow method is applied for modeling steady hydrodynamics of single asymmetric hulls and their catamaran setups. Numerical results are validated with available experimental data and empirical correlations. Parametric calculation results are presented for the lift coefficient and the center of pressure for variable hull geometry, spacings, and speed regimes. The lift coefficient is found to increase at smaller hull spacings and decrease at higher Froude numbers and higher deadrise angles.

Long-term variability of the cold subsurface water (CSW) in the Okhotsk Sea is analyzed on the base of all available oceanographic data collected in March through August of 1946-2015 (total 65,742 stations). The Integral Heat Content (IHC) is calculated for each station and average annual IHC anomalies of the cold subsurface water are determined by month and by 2-degree grid. The IHC anomaly series are analyzed using the EOF analysis. Cycles with period of approximately 30 years are revealed in the variations of the subsurface layer heat content. Thus, in the 1946-1950, its temperature decreased, but it grew since 2009-2010 to 2015. The warming of CSW was also observed in the 1951-1964 and 1978-1994, while the cooling was in the 1965-1977 and 1995-2008. Based on this criterion, the CSW thermal condition in certain years is classified as «extremely cold» in 2001, as «cold» in 1949, 1950, 1951, 1958, 1959, 1960, 1966, 1967, 1969, 1973, 1976, 1977, 1978, 1980, 1999, 2000, 2010, 2012, as «normal» in 1946, 1952, 1953, 1954, 1955, 1957, 1961, 1962, 1965, 1970, 1971, 1972, 1975, 1979, 1982, 1983, 1985, 1986, 1988, 1989, 1990, 1993, 1995, 1996, 1998, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2013, 2014, as «warm» in 1948, 1956, 1964, 1968, 1974, 1981, 1984, 1987, 1991, 1992, 1994, 1997, 2015, and as «extremely warm» in 1963. Statistically significant correlation is found between changes of the CSW thermal conditions and long-term variations of atmosphere and ocean climate indices, as well as local patterns of the atmosphere-ice-ocean interaction in the Okhotsk Sea and adjacent onshore and offshore areas of Asia and the Pacific Ocean.

Air-ventilated cavities formed under or around the hulls of marine vehicles can reduce water drag. Hull configurations with partial air ventilation where air cavities reattach to body surfaces are of special practical interest, since the required air supply rates to achieve significant drag reduction can be made rather low. However, formation and stability of such air cavities are sensitive to the hull geometry and operational conditions. In this study, an attempt is made to numerically simulate one setup with a partial air cavity that was previously tested experimentally at high Reynolds numbers, above 50 million. A computational fluid dynamics software Star-CCM+ has been employed for numerical modeling. Stable and unstable states of the air-cavity setup, characterized by long and collapsing air cavities, respectively, were modeled at two air supply rates near the stability boundary. Numerical results were similar to experimental data at the optimal water speed for the tested geometry, when a long air cavity was sustained at a minimal air supply rate. For water speeds that were substantially higher or lower than the optimal case, a stable cavity could not be maintained with small air supply rates for the given hull geometry. Numerical simulations demonstrated how alterations of the body surface could help sustain long air cavities across a broader speed range using air supply rates that were similar to the optimal case. These findings suggest that morphing hull surfaces can potentially be used for control of drag-reducing air cavities and expand the viable operating range for their application to marine vehicles.

Improving efficiency of hydrogen cooling in cryogenic conditions is important for the wider applications of hydrogen energy systems. The approach investigated in this study is based on a Ranque-Hilsch vortex tube (RHVT) that generates temperature separation in a working fluid. The simplicity of RHVT is also a valuable characteristic for cryogenic systems. In the present work, novel shapes of RHVT are computationally investigated with the goal to raise efficiency of the cooling process. Specifically, a smooth transition is arranged between a vortex chamber, where compressed gas is injected, and the main tube with two exit ports at the tube ends. Flow simulations have been carried out using STAR-CCM+ software with the real-gas Redlich-Kwong model for hydrogen at temperatures near 70 K. It is determined that a vortex tube with a smooth transition of moderate size manifests about 7% improvement of the cooling efficiency when compared vortex tubes that use traditional vortex chambers with stepped transitions and a no-chamber setup with direct gas injection.

Hard-chine boats are usually intended for high-speed regimes where they operate in the planing mode. These boats are often designed to be relatively light, but there are special applications that may occasionally require fast boats to be heavily loaded. In this study, steady-state hydrodynamic performance of nominal-weight and overloaded hard-chine hulls in calm water is investigated with computational fluid dynamics solver program STAR-CCM+. The resistance and attitude values of a constant-deadrise reference hull and its modifications with more pronounced bows of concave and convex shapes are obtained from numerical simulations. On average, 40% heavier hulls showed about 30% larger drag over the speed range from the displacement to planing modes. Among the studied configurations, the hull with a concave bow is found to have 5–12% lower resistance than the other hulls in the semi-displacement regime and heavy loadings and 2–10% lower drag in the displacement regime and nominal loading, while this hull is also capable of achieving fast planing speeds at the nominal weight with typical available thrust. The near-hull wave patterns and hull pressure distributions for selected conditions are presented and discussed as well.

Three commercially available extractants (tri-butyl-phosphate (TBP), di-(2-ethylhexyl)phosphoric acid (HDEHP) and Aliquat 336 (a mixture of quaternary ammonium bases)) were tested for separation of Pr(III) and Nd(III) in both static and dynamic modes. In the case of HDEHP, phase stability and influence of nitric acid were considered. Extraction isotherms were constructed, and influence of water-soluble complexing agents on the separation factor was investigated for Aliquat 336. In the case of TBP, influence of calcium nitrate in aqueous phase on the extraction efficiency was investigated. Model countercurrent experiments were conducted for TBP and Aliquat 336. It was shown that TBP is the best choice due to its high capacity and cation extraction order (Nd > Pr).

We have synthesized and examined several complexes of lanthanides with diamides of 2,2′-bipyridyl-6,6′-dicarboxylic acid bearing various hetaryl-based side chains for the elucidation of the effect of the heterocycle on the structure and properties of the ligands. The multigram scale methods for the preparation of various N-alkyl-hetaryls and their diamides were developed. The solid state structure of 6-methyl-2-pyridylamide of 2,2′-bipyridyl-6,6′-dicarboxylic acid possesses a flat structure where the conformation is completely different from that previously observed for N-alkylated 2,2′-bipyridyl-6,6′-dicarboxamides and 2,6-pyridinedicarboxamides. The complexes of new ligands were synthesized and NMR and X-Ray studied their structure in solution and solid state. The results demonstrate that complexes possess the same structures both in solid state and in solution. Stability constants of the complexes were less when comparing with dimethyl-substituted diamides, but higher than for unsubstituted dianilide. Contrarily, the extraction ability of 2-pyridyl-diamide is significantly lower than for corresponding anilide. Specific interaction of extractant with solvent molecules, which is not available for electron-sink pyridine amides, can explain this. The luminescence of new Eu complexes was significantly higher than for all previously 2,2′-bipyridyl-6,6′-dicarboxamides and QY reaches 18%. Asymmetry ratios of Eu complexes were 25% higher when compared other complexes with 2,2′-bipyridyl-6,6′-dicarboxamides, which indicates large deviation from the inversion center.

Spatial distribution and seasonal and interannual variability are determined for parameters of the upper mixed layer and seasonal thermocline in the western deep basin of the Bering Sea in summer and fall of 2002-2013 and compared with chlorophyll- a concentration at the sea surface. The mixed layer is formed by solar heating of the sea surface and wind mixing. Its thickness doesn’t exceed 10-15 m in summer but increases up to 25-40 m in fall. The thermocline becomes deeper from summer to fall, too, in particular its lower bound that sinks from 37 to 48 m, on average; however, its thickness decreases from 20-25 to 16-22 m and temperature and density gradients increase from 0.23-0.25 to 0.37-0.45 °C/m and from 0.032 to 0.062 units/m, respectively, that means that the thermocline becomes steadier. Tendency to cooling was observed for both layers in the last decade, the process was more visible in autumn, with a shift at the upper bound of thermocline (from the mean temperature of 9.8 °C in 2002-2006 to the mean temperature of 8.4 °C in 2007-2013) and gradual decreasing at its lower bound (from 3.3 °C in 2003 to 2.1 °C in 2013), and not so obvious in summer. Year-to-year fluctuations of salinity in summer/autumn were within the limits 32.77-33.03/32.60-32.96 psu for the upper bound of the thermocline and 32.98-33.14/33.06-33.13 psu for its lower bound and had slight negative tendency. In both seasons, the mixed layer depth has significant negative correlation with the temperature at the upper bound of the thermocline (R2 = 0.6) and the temperature at the lower bound of the thermocline correlates significantly with salinity at its both bounds (R2 > 0.4). Spring bloom of chlorophyll- a has no relationship neither with temperature in the mixed layer in April and May, nor with the rate of warming between these months. Strong fall bloom of chlorophyll- a develops if the fall cooling begins in conditions of high temperature at the sea surface (> 6 °C) that negatively depends on the mixed layer thickness, so slow cooling and delay of the fall mixing are favorable for chlorophyll- a blooming in autumn.

High-speed heavy loaded monohull ships can benefit from application of drag-reducing air cavities under stepped hull bottoms. The subject of this paper is the steady hydrodynamic modeling of semi-planing air-cavity hulls. The current method is based on a linearized potential-flow theory for surface flows. The mathematical model description and parametric calculation results for a selected configuration with pressurized and open air cavities are presented.

Developed and investigated radiometric system EHF (extremely high frequency) range for the diagnosis of tissue samples affected by carcinoma. EHF system are significantly higher than in the possibility of identifying a lower frequency range, as in UHF band (UHF band) and UHF (ultra high frequency) resolution of 1-3 mm are impossible. It was established that the affected carcinoma tissue samples are 3 dB lower transmittance compared to unaffected tissues. Analysis of the dependency of the harmonic components of the modulation signal passing through the examined tissue samples shows dramatic difference in the behavior of the harmonic components of the frequency domain. This phenomenon appears to altered tissue the presence of slumps that due to the interaction of electromagnetic waves with the tissue samples may be explained by the so-called stochastic resonance effect.

High-speed marine vehicles can take advantage of aerodynamically supported platforms or air wings to increase maximum speed or transportation efficiency. However, this also results in increased complexity of boat dynamics, especially in the presence of waves and wind gusts. In this study, a mathematical model based on the fully unsteady aerodynamic extreme-ground-effect theory and the hydrodynamic added-mass strip theory is applied for simulating vertical-plane motions of a tunnel hull in a disturbed environment, as well as determining its steady states in calm conditions. Calculated responses of the boat to wind gusts and surface waves are demonstrated. The present model can be used as a supplementary method for preliminary estimations of performance of aerodynamically assisted marine craft.

A method of hydrodynamic discrete sources is applied for two-dimensional modeling of stepped planing surfaces. The water surface deformations, wetted hull lengths, and pressure distribution are calculated at given hull attitude and Froude number. Pressurized air cavities that improve hydrodynamic performance can also be modeled with the current method. Presented results include validation examples, parametric calculations of a single-step hull, effect of trim tabs, and performance of an infinite series of periodic stepped surfaces. It is shown that transverse steps can lead to higher lift-drag ratio, although at reduced lift capability, in comparison with a stepless hull. Performance of a multi-step configuration is sensitive to the wave pattern between hulls, which depends on Froude number and relative hull spacing.

Wing-in-Ground vehicles and aerodynamically assisted boats take advantage of increased lift and reduced drag of wing sections in the ground proximity. At relatively low speeds or heavy payloads of these craft, a flap at the wing trailing-edge can be applied to boost the aerodynamic lift. The influence of a flap on the two-dimensional NACA 4412 airfoil in viscous ground-effect flow is numerically investigated in this study. The computational method consists of a steady-state, incompressible, finite volume method utilizing the Spalart-Allmaras turbulence model. Grid generation and solution of the Navier-Stokes equations are completed using computer program Fluent. The code is validated against published experimental and numerical results of unbounded flow with a flap, as well as ground-effect motion without a flap. Aerodynamic forces are calculated, and the effects of angle of attack, Reynolds number, ground height, and flap deflection are presented for a split and plain flap. Changes in the flow introduced with the flap addition are also discussed. Overall, the use of a flap on wings with small attack angles is found to be beneficial for small flap deflections up to 5% of the chord, where the contribution of lift augmentation exceeds the drag increase, yielding an augmented lift-to-drag ratio.

This article presents the results of vagus nerve chronic stimulation in 11 patients with pharmacoresistant epilepsy who are not on the wait-list for direct surgical treatment. During the first three months of nervestimulation 27,3% of patients demonstrated a 50% seizure-frequency reduction as compared to baseline, with no surgical or infectious complications. 27,3% Of patients demonstrated transient side effects of nerve stimulation, such as dysphonia, trouble breathing or throat paresthesias.