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The paper investigates commercially pure titanium VT1-0 (US analog Grade 2) in the ultrafine grain state after the aluminum ion implantation at a fluence of 1∙1017, 5∙1017 and 10∙1017 ion/cm2. The investigation techniques include X-ray diffraction analysis, scanning electron microscopy with energy dispersive X-ray analysis, and transmission electron microscopy. Auger electron spectrometer is used to analyze the chemical composition of the implanted layer. The grain size in the longitudinal and transverse directions and the phase composition of ultrafine titanium are studied depending on the irradiation exposure. It is found that the ion implantation leads to the formation of such intermetallic compounds as Al3Ti and AlTi3 phases, β-phase titanium and aluminum oxide (Al2O3). The increased irradiation exposure results in the formation of a thicker implanted layer without changing its phase composition.

Electrodialytic concentration of ammonium-containing liquid products of biochemical processing of municipal, industrial, and livestock wastewater is a promising method for obtaining cheap liquid fertilizers for agriculture. At the same time, it is known that electrodialysis of NH4Cl solutions fails to achieve the same high brine concentrations as in the case of other chlorides, for example, KCl. We show that the reason is high diffusion permeability of anion-exchange membranes (AEMs) to NH4Cl, which is due to the protonation–deprotonation reactions of ammonium coions during their transfer from an external solution to an internal AEM solution and vice versa. For the first time, a mathematical model of NH4Cl diffusion through AEM was proposed with allowance for these reactions. The experimental values of the diffusion permeability of an anion-exchange membrane AMX and a cation-exchange membrane CMX in NH4Cl and KCl solutions have been compared. between The results of calculating the diffusion permeability of the membrane AMX in NH4Cl solutions are in qualitative agreement with the experiment data.

To date, it has been established that in the progression of cardiovascular (CV) disorders, an increase in the level of homocysteine (HC) and hypovitaminosis D play an important role. According to the latest recommendations, the modern clinician should consider risk factors not as a diagnostic sign, but as a prognostic, contributing factor, which to some extent can lead to destructive changes in the vascular wall. The aim. To study the morphological changes of the vascular wall depending on the degree of hyperhomocysteinemia and hypovitaminosis D. Materials and methods. We analyzed data from 54 patients who, in addition to determining the level of HC and vitamin D, underwent morphological studies of fragments of the great saphenous vein and aorta. Samples were obtained during coronary artery bypass grafting. Depending on the degree of hyperhomocysteinemia and the level of vitamin D, the patients were divided into 3 groups. Results. Morphological examination of the great saphenous vein and aorta showed normal structure of the vascular wall in patients with normal levels of HC and vitamin D (78.5% and 71.4%, respectively). Patients from the groups 2 and 3 with hyperhomocysteinemia had more pronounced changes in the venous wall, regardless of the level of vitamin D. These data suggest a probable association of HC levels with the changes in the vascular wall. It was also noted that the patients of group 3 had more pronounced inflammatory infiltration of the vascular wall. Conclusions. Hyperhomocysteinemia and hypovitaminosis D are independent predictors of CV disorders and have a detrimental effect on the vascular wall and blood coagulation system, creating conditions for the progression of atherosclerosis. The higher is the level of HC, the more pronounced are morphological changes in the vascular wall of the vein, leading to hypertrophy of all layers, regardless of the level of vitamin D.

For many years, cardiovascular diseases have been a major cause of morbidity and mortality worldwide. In modern society these have become one of the most pressing medical and social problems. To date, progression of coronary heart disease (CHD) and its complications is strongly associated with increased homocysteine (HC) level and hypovitaminosis D. However, medical literature does not sufficiently cover the issues of drug treatment of patients with metabolic disorders after coronary artery bypass grafting, therefore, more detailed study of this problem is required. The aim. To develop a differentiated approach to the medical treatment of CHD patients before and after direct myocardial revascularization. Materials and methods. The study analyzed the data of 133 patients, 117 (87.96%) men and 16 (12.03%) women, diagnosed with CHD. In these patients, the levels of homocysteine and vitamin D were evaluated. Depending on the levels of hyperhomocysteinemia and vitamin D, the patients were divided into 3 groups. Results. About 70% of the patients examined had elevated blood homocysteine levels greater than 15 ¤mol/L. Based on selective CAG (MSCT CA) findings and complete examination, myocardial revascularization was indicated in 133 patients, as recommended by the 2018 ESC/EACTS Guidelines on myocardial revascularization. In 95% of cases (126 patients), direct myocardial revascularization was performed. All the patients received standard therapy preoperatively, and after getting results of HC and vitamin D tests, metabolic therapy, including folic acid, vitamins B6, B12 and D, depending on HC and vitamin D levels, was prescribed. Conclusions. Hyperhomocysteinemia and hypovitaminosis D provoke impaired endothelial vasomotor function and activate neointimal hyperplasia. Patients with hyperhomocysteinemia and vitamin D deficiency should receive metabolic therapy based on folic acid, vitamins B 6 and B12, and vitamin D, both preoperatively and postoperatively. The first control of HC and vitamin D levels is carried out within 3 months after the treatment initiation.

To date, it has been established that in the progression of coronary artery disease (CAD) and its complications, an increase in the level of homocysteine and hypovitaminosis D are essential. However, medical publications do not adequately cover the study of the effects of hyperhomocysteinemia and vitamin D deficiency on the course of atherosclerosis and the functional state of the myocardium, and requires more detailed research of this problem. Objective. To study the functional state of the myocardium depending on the degree of hyperhomocysteinemia and hypovitaminosis D in patients with CAD. Materials and methods. The study analyzed data from 69 diagnosed with CAD. Depending on the degree of hyperhomocysteinemia and the level of vitamin D, patients were divided into 3 groups. Results. In all patients, speckle-tracking echocardiography revealed a decrease in longitudinal and circular myocardial deformation. Patients with hyperhomocysteinemia and vitamin D deficiency had significantly lower myocardial deformity. Comparing the data of echocardiography, it was found that in patients of all three groups – no significant difference in hemodynamic parameters was found, despite the difference in the level of HC and vitamin D. Conclusions. Hyperhomocysteinemia and hypovitaminosis D are risk factors for the development of CAD. It was revealed that the higher level of homocysteine and the pronounced deficiency of vitamin D, are associated with more pronounced changes in the functional state of the myocardium.

Using the transmission electron microscopy of thin foils the paper studies the phase composition and fine structure of 0.18С–1Cr–3Ni–1Mo–Fe steel after plasma electrolytic carbonitriding carried out through the surface saturation with nitrogen and carbon. The steel specimens are studied before and after carbonitriding on the surface and at a ~40 μm distance from the surface. It is found that carbonitriding causes significant qualitative and quantitative changes in the steel structure. Thus, the layers of residual austenite appear along the boundaries of martensitic lamellas, and the particles of alloyed cementite and carbonitrides are observed inside the lamellas. The layers of residual austenite locate at a ~40 μm depth along the boundaries of all martensitic crystals, while inside the crystals there are only particles of alloyed cementite and carbonitride M23(C, N)6. The control parameter of changes in the structure and phase composition is the concentration of interstitial atoms of carbon and nitrogen. Changes in this concentration lead to the system deviation from thermodynamic equilibrium. The transition of system to equilibrium or quasi-equilibrium states is considered to be performed through the transition of crystal lattices, which form a gradient structural-unstable state of the matrix, intermetallics and carbonitride compounds, to a low-stability state.

A method for determining the partial currents of orthophosphoric acid anions in an anion exchange membrane during electrodialysis desalination of a dilute (0.02 M) NaH2PO4 solution is proposed. This method has been used to study mass transfer in systems containing a homogeneous anion exchange membrane, AMX (Astom, Japan), and a heterogeneous anion exchange membrane, MA-41P (Shchekinoazot, Russia). It is shown that, passing into these membranes, single-charge anions of orthophosphoric acid are turned into double-charge anions. This transformation leads to an increase in the registered current but is not accompanied by an increase in the transfer of the target component, pentavalent phosphorus. A decrease in the proportion of the conducting surface of heterogeneous membranes compared to homogeneous ones enhances this process due to an increase in the local current density in the conducting areas. A comparison made for correctly determined limiting currents allows us to conclude that in the case of using a homogeneous membrane, the overlimit transfer for pentavalent phosphorus is only slightly inferior to that achieved for chlorine ions during NaCl solution desalting.

The extraction of valuable components from brackish waters, such as lithium ions, is of considerable practical interest. A promising approach is the separation of solutes by their physical properties, such as charge and diffusion coefficient. We propose a simple one-dimensional model of ion transport in an electro-baromembrane system with a track-etched membrane, which makes it possible to calculate the flux densities of the separated components across the membrane as functions of the applied voltage and pressure drop. The model takes into account the parameters of the membrane (pore radius, length, and volume fraction in the membrane), hydrodynamic, and other external conditions of the separation process (thickness of diffusion layers, composition of the feeding and receiving solutions). The calculation results are given for a mixed solution containing three sorts of ions (two cations, K+ and Li+, and one anion, Cl−) with different diffusion coefficients, but the same absolute value of the charge. The electric field and the pressure drop are superimposed in such a way that the electromigration and convective transport of ions in the pore are directed oppositely. Since the mobility of competing cations is different, only lithium chloride or only potassium chloride is removed from the mixture at certain values of the potential drop and pressure.

The principle of operation and the characteristics of the experimental equipment intended for the generation of boron ion plasma and beams are presented. The equipment comprises a vacuum arc source of boron ions with boron isotope separation in a magnetic field and a plasma generator for deposition of boron-containing coatings based on a planar magnetron sputter. Common to this equipment is the use of lanthanum hexaboride cathodes, but for planar magnetron, a pure boron cathode heated in the discharge is also used. It is shown that, when silicon wafer is implanted with beams of 10B+ and 11B+ boron isotope ions with doses of 1014–1016 ion/cm2, the isotopic effect of the diode properties of the implanted surface is observed. The results of studies of the properties of the obtained boron-containing coatings on model materials: stainless steel, crystal silicon, and E110 (Zr–1Nb) reactor alloy are presented.

The paper presents the transmission electron microscopy investigations of the structure and phase composition of ferritic-perlitic ST2 steel surface after electrolytic plasma quenching. The steel in the initial state represents the material after hardening at 890°С for 2 or 2.5 hours and quenching in warm (30–60°С) water with subsequent tempering at 580°C for 2.5 or 3 hours. Electrolytic plasma quenching is carried out at 850–900°С in an aqueous salt solution for 4 seconds, at 320 V voltage and 40 A current. In the initial state, the morphology of the steel matrix consists of lamellar perlite and nonfragmented and fragmented ferrite. Electrolytic plasma quenching of the steel surface results in the martensite transformation, steel self-tempering, and the formation of cementite particles in all martensite crystals. This treatment also leads to the diffusion transformation of γ → α phases, the release of residual austenite (γ -phase) along the low-temperature martensite laths and lamellas and in all crystals of lamellar martensite, the formation of М23С6 special carbides and, finally, to the enhancement of all parameters of the steel fine structure.

Ultrafiltration and nanofiltration membranes that are traditionally used in baromembrane processes have become increasingly frequently applied in electromembrane and baroelectromembrane processes. In the latter case, two driving forces, an electric field and a pressure gradient, are simultaneously used. This study presents data on the specific electrical conductivity, diffusion permeability, and transport numbers of ions as well as current–voltage characteristics and chronopotentiograms of AMN-P and OPMN-P weakly ionized nanofiltration membranes and a number of track membranes in solutions of NaCl and CaCl2. The relationship of obtained characteristics with the structure and exchange capacity of membranes is discussed. It is shown that both nanofiltration and track membranes can exhibit a quite high selectivity towards the electrical transport of ions with a certain charge sign. Such selectivity is especially high in respect of the transport of Ca2+ ions. In the case of an AMN-P membrane, the transport number of Ca2+ reaches 0.98, while it is noticeably lower for Na+ ions. This result correlates well with a known fact about a higher rejection coefficient of doubly charged ions in comparison with singly charged ions in baromembrane processes. Track membrane #115 is also distinguished by high selectivity in respect of cations, the transport number of sodium ions in it is close to 0.96.

The paper presents the transmission electron microscopy investigations of the microstructure and phase composition of the nickel-based superalloy after high temperature annealing. All states of the superalloy are characterized by the single-crystal structure with [001] crystallographic orientation. The Ni–Al–Co alloy system also contains such elements as Mo, Cr, W, Ta, Re and Ru. The Ni–Al–Co system is studied in four states: initial (after directional crystallization) and after 1000°С annealing during 118, 372 and 1274 hours. The major phases forming the alloy system are γ- and γ′-phases. After annealing for 118 hours, the formation of Al6(Re, Ru) phase is observed. After longer high-temperature annealing new phases occur, such as σ-, δ- and Laves phase. The obtained alloy microstructure is classified into four types: 1) γ′-phase quasi-cuboids with γ-phase layers, 2) ribbon anisotropic microstructure of γ′+ γ-phase, 3) ribbon anisotropic microstructure with σ-phase particles in γ-phase layers, 4) γ-phase with δ-phase and Laves phase inclusions. The introduction of a large amount of various alloying elements and the annealing process modify the crystallographic texture of the superalloy.

An actual problem in surgical practice is paresis of the gastrointestinal tract, the main manifestation of which is constipation after surgical treatment. Treatment of postoperative gastrointestinal paresis, which is manifested primarily by constipation, should be comprehensive and, if necessary, patients are shown taking laxatives to stimulate bowel function.Sodium picosulfate is one of the most commonly used and effective drugs, belongs to the group of synthetic stimulant laxatives. The above review noted the safety and effectiveness of sodium picosulfate for atonic constipation, for regulating stool (hemorrhoids, proctitis, anus cracks), for preparing for surgical operations, instrumental and radiological examinations.The presence of picosulfate in the clinic and hospital surgeon’s arsenal makes it possible to optimize the drug therapy in surgical patients with constipation syndrome at the hospital and outpatient treatment stage.

The present study was conducted by transmission electron microscopy (TEM) in order to investigate the structure of multicomponent nickel-based alloy obtained by directional solidification and change in its phase composition at high-temperature annealing. All states of the alloy possessed monocrystalline structure with [001] orientation. The alloy under study contained other elements apart from Ni, such as: Al, Co, and also Mo, Cr, W, Ta, Re, and Ru. The alloy was investigated in three states after annealing for: 1) 118 h; 2) 372 h; 3) 1274 h at 1000°С. The basic phases that form the alloy were γ and γ′. In the state after annealing for 118 h Al6(Re,Ru) phase was observed in an insignificant amount. After longer high temperature annealing new phases occurred, such as σ-phase and δ-phase, Laves phase. The structures occurring during annealing can be classified into four types: 1) quasi-cuboids, 2) anisotropic stripe structures, 3) anisotropic structures of striped type with σ-phase separation, 4) structureless zones with large two-phase areas.

This paper presents scanning and transmission electron microscope investigations of the structure, phase composition, and morphology of a heat-resistant alloy modified by thermal treatment and additionally alloyed by rhenium. The rhenium alloy was obtained by using the directional crystallization technique. The structural investigations were carried out for two states of the alloy, i.e., (1) original (after the directional crystallization); (2) after the directional crystallization with 1150 °C annealing for 1 h and 1100 °C annealing for 480 h. It is shown that fcc-based γ- and γ′-phases are primary in all states of the alloy. The γ′-phase has an L12 structure, while γ-phase is a disordered phase. It was found that after directed crystallization, the volume fraction of the γ′ phase is ~85%, the fraction of the γ-phase is less than 10%. Annealing leads to an increase in the γ′- phase up to 90%, the proportion of the γ-phase practically does not change. Rhenium is a phase-formation element. The investigations show that high-temperature annealing modifies the structural and phase conditions of the heat-resistant alloy.

Modern QSAR approaches have wide practical applications in drug discovery for designing potentially bioactive molecules. If such models are based on the use of 2D descriptors, important information contained in the spatial structures of molecules is lost. The major problem in constructing models using 3D descriptors is the choice of a putative bioactive conformation, which affects the predictive performance. The multi-instance (MI) learning approach considering multiple conformations in model training could be a reasonable solution to the above problem. In this study, we implemented several multi-instance algorithms, both conventional and based on deep learning, and investigated their performance. We compared the performance of MI-QSAR models with those based on the classical single-instance QSAR (SI-QSAR) approach in which each molecule is encoded by either 2D descriptors computed for the corresponding molecular graph or 3D descriptors issued for a single lowest energy conformation. The calculations were carried out on 175 data sets extracted from the ChEMBL23 database. It is demonstrated that (i) MI-QSAR outperforms SI-QSAR in numerous cases and (ii) MI algorithms can automatically identify plausible bioactive conformations.

Transmission electron microscopy investigations were carried out to study the structural-phase state of ultra-fine grain (UFG) titanium with the average grain size of ~0.2 μm, implanted with aluminum ions. Implantation was carried out on MEVVA-V.RU ion source at room temperature, exposure time of 5.25 h and ion implantation dosage of 1⋅1018 ion/cm2. UFG-titanium was obtained by a combined multiple uniaxial compaction with rolling in grooved rolls and further annealing at 573 К for 1h. The specimens were investigated before and after implantation at a distance of 70-100 nm from the specimen surface. Concentration profile of aluminum implanted with α-Ti was obtained. It was revealed that the thickness of implanted layer was 200 nm, while maximum aluminum concentration was 70 at.%. Implantation of aluminum into titanium has resulted in formation of the whole number of phases having various crystal lattices, like β-Ti, TiAl3, Ti3Al, TiC and TiO2. The areas of their localization, the sizes, distribution density and volume fractions were determined. Grain distribution functions by their sizes were built, and the average grain size was defined. The paper investigates the influence of implantation on the grain anisotropy factor. It was revealed that implantation leads to the decrease in the average transverse and longitudinal grain size of α-Ti and decrease in the anisotropy factor by three times. The yield stress and contributions of separate strengthening mechanisms before and after implantation were calculated. The implantation has resulted in increase in the yield stress by two times.

Using the transmission electron microscopy technique, we have studied the structural-phase state of UFG titanium with an average grain size ~0.2 μm implanted with aluminum ions. An MEVVA-V.RU source has been used to implant the specimen at room temperature, implantation time 5.25 h, and irradiation dose 1 · 1018 ion/cm2. To produce the UFG titanium samples, we have employed the combined multiple uniaxial pressing technique (abc-pressing) followed by grooved rolling and subsequent annealing at 573 K for 1 h. The samples have been studied in two states: 1) before implantation (initial state) and 2) after implantation at a distance 70–100 nm from the sample surface. We have obtained the aluminum concentration profile of implanted α-Ti. It has been established that the maximum concentration of aluminum is 70 at.% and the thickness of the implanted layer is 200 nm. We have determined the grain distribution functions over the grain size, calculated the grain anisotropy coefficient before and after implantation. It has been established that implantation decreases the average longitudinal and transversal sizes of α-Ti grains, and reduces the anisotropy coefficient by three times. It has been established that aluminum implantation into titanium brings about formation of a whole set of phases with different crystal lattices, namely, β-Ti, TiAl3, Ti3Al, TiC, and TiO2.

Carbide–boride coatings applied on both sides of V96Ts aluminum alloy samples by electric spark alloying (ESA) are metallographically studied. The coated samples are processed by laser on one side. Laser treatment of the surface decreases the pronounced roughness, pores, and cracks visible after ESA. Laboratory tests suggest combined (electric-spark–laser) hardening of the surface of V96Ts aluminum alloy samples to extend the service life of tools and machine parts.

The current methods for determination of the membrane specific permselectivity between two competing counter-ions are dependent on various factors, which hinder the comparison of ion selectivity of ion selective membranes. In this work, a new characteristic, “ideal selectivity” is suggested to be used for the evaluation of the specific permselectivity of monovalent selective membranes. Ideal selectivity is determined in a single electrolyte solution containing only one of the competing counterions. We show that this characteristic exhibits a stable value, which is independent from the molar fraction of ions in a solution. Thus, it may be directly used to predict the purity of a salt produced in a dynamic selectrodialysis (SED) process with a monovalent selective membrane. To elaborate this, thin film composite (TFC) cation exchange membranes were prepared with piperazine and trimesoyl chloride by interfacial polymerization. These membranes were compared with a commercial monovalent selective cation exchange membrane CIMS (ASTOM, Japan) in view of their permselectivity (Na+/Mg2+) and the performance in SED. The results show that when the TFC membranes were applied in SED, the purity of Mg2+ in the product reached 75%, which was higher than in the case of CIMS. Furthermore, ideal selectivity of those TFC and CIMS membranes were calculated and fitted with the experimental Mg2+ purity. It was found that ideal selectivity linearly correlates with the product final purity. The extrapolation of the fitting line predicts that when ideal selectivity approaches to 2, SED process the purity could theoretically approach to 100% in the same experimental conditions. Therefore, ideal selectivity can be used to predict the separation efficiency and the final product purity of SED process.

The object of the research is oxidized nickel ores from the Kulikovskoye deposit (Southern Urals) – non-conforming nickel-containing raw materials. The work is devoted to the study of chemical and phase composition to substantiate the choice of the method of processing this material in order to obtain valuable inorganic substances in demand in the chemical and metallurgical industries: oxide and (or) magnesium nitrate, iron and nickel containing concentrates, silicon dioxide. The chemical composition of ore demonstrating the feasibility of developing a technology for its complex processing is presented. X-ray phase analysis showed the presence of silicates of the serpentine group (lizardite-1M and lizardite-1T) and the group of spinelids (magnesioferrite) in the oxidized nickel ores of the Kulikovskoye deposit. A literary analysis suggested the presence of other hydrosilicates (antigorite, chrysotile, nimite, talc, revdinskite, clinochlore, etc.). IR spectroscopic analysis was performed to confirm the phase composition. A thermogravimetric analysis was performed, which makes it possible to determine the conditions for the preliminary preparation of ground raw materials. To determine the mechanism of thermal decomposition of ore in air, intermediate products were obtained at temperatures of 600, 700 and 900 °C. According to X-ray diffraction, IR and Raman spectroscopic analyzes, at 600 °C, the removal of OH groups, water molecules and the destruction of the crystal lattices that make up the mineral ore with the formation of oxides (FeO, SiO2, MgO) begins. At 700 °C, island silicates are formed: forsterite Mg2SiO4, larnite Ca2SiO4. At 900 °C, the interaction between silicates continues with the complication of the composition of functional groups. Based on the described properties of minerals and previous work on the hydrometallurgical technology of processing oxidized nickel ores and metal-containing silicate raw materials in order to obtain inorganic substances, nitric acid is proposed as a leaching agent.

Structural (volume fractions of the gel phase and the intergel solution) and transport (electrical conductivity, diffusion permeability, transport numbers of counterions and coions) characteristics of cation-exchange (CMX, MK-40) and anion-exchange (AMX, MA-41) membranes in NaCl, CaCl2, and Na2SO4 solutions have been studied. The investigated membranes have the same chemical nature of the ion-exchange matrix and similar values of ion-exchange capacity, but they differ in the degree of heterogeneity and chemical nature of the reinforcing materials. The difference in the properties between heterogeneous (MK-40 and MA-41) and (conventionally) homogeneous (CMX and AMX) membranes is due to the fact that the heterogeneous membranes have macropores, whereas the homogeneous membranes do not have such pores. It has been shown that the largest macropores, which basically determine the high diffusion permeability of heterogeneous membranes, are formed at the boundaries of reinforcing fabric threads and the composite material. Regarding the influence of the electrolyte nature, the sorption of coions of the membrane gel phase (not containing macropores) is of primary importance; the sorption of coions, as well as diffusion permeability and the transport number of coions, increase in the order: 1 : 2 < 1 : 1 < 2 : 1, where the first numeral is the charge of the counterion and the second one is that of the coion. An important role, especially in the case of heterogeneous membranes, is played by the electrolyte diffusion coefficients in the electroneutral solution that fills the central part of meso- and macropores.

The paper presents research into the structure and phase composition of Ni–Al–Co alloy modified by rhenium (~3 аt.%) alloying. Observations are carried out using the transmission electron microscopy. The initial state of the alloy is the state after the directional crystallization. The alloy is further subjected to 900°С annealing during 1143 h. Creep tests are additionally carried out for this alloy at the same temperature and time and 400 MPa load. It is shown that FCC disordered γ- and ordered γ′-phases are major in all alloy states. Secondary phases are found to be σ-phase, χ-phase, Laves and AlRe2 phases. Experiments show that the high temperature annealing changes the phase composition of the alloy. Thus, the amount of the ordered γ′-phase increases, while that of disordered γ-phase decreases. During the creep process, the amount of the former reduces and the amount of the latter increases. The annealing process modifies the phase composition in secondary phases. It is found that the structural modification caused by the creep process differs from that caused by the annealing process. Thus, the creep-induced modification of the cuboid structure in γ′-phase is stronger than due to annealing. Dislocations are observed in γ- and γ′-phases in all states of the alloy. During the annealing process, the dislocation density in γ-phase is higher than in γ′-phase, and vice versa during the creep process. The experiments show that the behavior of the dislocation structures is different during the annealing and creep processes.

It is known that some components of the bathing solution can enhance water splitting at depleted solution/ion-exchange membrane interface via protonation/deprotonation reactions with water. In this paper, we show that not only the presence of such components is important, but also a mechanism ensuring their sufficiently high concentration near the membrane surface. A comparative study of the electrochemical behavior of a Neosepta® homogeneous cation-exchange CMX and an anion-exchange AMX membranes (Astom, Japan) in 0.02 M KCl or 0.02 M NH4Cl solutions is carried out. The NH4+/NH3 couple is an effective catalyst of water splitting. The deprotonation reaction rate constant of the NH4+ ions, which limits the rate of water splitting, is about 10 s−1. It is almost 6 orders of magnitude greater than the rate constant for direct water dissociation in free solution. A comprehensive electrochemical characterization of the membrane systems is made: voltammetry, chronopotentiometry, electrochemical impedancemetry, and pH-metry (including color indication of the pH of the membrane internal solution). It is found that the water splitting rate at the interface of the AMX membrane in the NH4Cl solution is essentially higher than in the KCl solution. The difference in the rates of this reaction in KCl and NH4Cl solutions at the CMX membrane is insignificant. The reason for the weak effect of the NH4+/NH3 couple on the rate of water splitting at the CMX membrane is that the concentration of both NH4+ and NH3 species is very low near its surface if the current density is close to or higher than its limiting value. As for the AMX membrane, we show that the ammonia-containing species can be transported to its depleted surface from the enriched solution by back “facilitated” diffusion through the membrane and this transport plays a crucial role in the occurrence of the rapid water splitting.

It has been found that after 300 h of operation of AMX and AMX-Sb anion-exchange membranes (Astom, Japan) in overlimiting current regimes in the process of electrodialysis desalination of 0.02 M NaCl, NH4Cl, NaH2PO4, and KC4H5O6 (KHT) solutions, the limiting currents, $$i_{{\lim }}^{{\exp }}$$ , determined by graphic processing of current–voltage curves increase in the order NaCl < NaH2PO4 < KHT. Their increments relative to those for the “fresh” membrane are 33, 90, and 128%, respectively. The growth in $$i_{{\lim }}^{{\exp }}$$ is accompanied by an increase in the thickness of the samples occurring in the NaH2PO4 and KHT solutions. In the case of NH4Cl, the values of $$i_{{\lim }}^{{\exp }}$$ decrease. It has been shown that a small decrease in counterion transport numbers during membrane operation has almost no effect on the values of limiting currents. The main contribution to the increase in $$i_{{\lim }}^{{\exp }}$$ is apparently made by electroconvection, which develops according to the mechanism of electroosmosis of the first kind. Its development is facilitated by the growth in the number and size of free-standing micrometer-sized cavities on the surface of anion-exchange membranes, the area and linear dimensions of which increase in the order NaCl < NaH2PO4 < KHT. These cavities are formed as a result of enhancement of electrochemical degradation of the ion-exchange material and the inert filler polyvinyl chloride at the membrane/solution interface in ampholyte solutions.

Diffusion dialysis (DD) is an environmentally appropriate method for separating components, which are unstable under the external influences (high temperature, high pressure, presence of electric field). The roadblock to the wider application of the DD method for separation and purification of amino acids is relatively low rate and selectivity of diffusion transport of these substances through ion-exchange membranes. In this paper, mechanisms of amino acid selective transport and possibilities to increase its flux across a cation-exchange membrane are considered. In particular, the effect of replacement of a flat membrane with a profiled one, prepared by the method of hot pressing, when using the same material is examined. Experimental and theoretical study is carried out using solutions of phenylalanine amino acid and NaCl when applying a commercial flat MK-40 cation-exchange membrane and its modification MK-40pr with profiled surface. It is found that the relatively high selective transport of phenylalanine is due to its facilitated diffusion, while the NaCl diffusion is reduced by the Donnan effect. The MK-40pr membrane allows a 8-fold increase in phenylalanine flux in comparison with the MK-40 membrane. This increase in partly due to the increased surface available for mass transfer (in 2.3 times), but also to better hydrodynamics reducing the diffusion layer thickness and to a higher fraction of conductive surface and higher pore radius. The latter is caused by water evaporation within the membrane pores in the course of its profiling.

This paper concerns the mechanisms of aging of ion-exchange membranes (IEMs) during their use in electrodialysis (ED) of food industry solutions containing polyphenols (PPs), as well as their cleaning. The study focuses on anion-exchange membranes (AEMs); their behavior is compared with that of cation-exchange membranes (CEMs). First, physicochemical static characteristics, structural, morphological and tensile strength parameters are determined for new AEMs and two batches of used AEMs at different duration of their use in industry, subjected to regular “Cleaning In Place”. Second, non-aggressive and economic ex-situ static cleaning methods involving the application of NaCl at 35 g L−1, a reconstituted seawater and a water-ethanol mixture acidified with H2SO4 were examined. During the cleaning process, the evolution of physicochemical parameters, such as ion-exchange capacity (IEC), electrical conductivity (κm) and contact angle (θ), were followed. It is shown that the application of NaCl solution has a negligible effect on IEC and κm; when soaking the membranes in the reconstituted seawater, κm even slightly decreases; however, there is a significant increase in these parameters when soaking the membranes in the acidified water-ethanol solution. As for the mechanism of fouling, PPs are the main responsible constituents. Apparently, they form dense colloidal nanoparticles not permeable for ions within membrane meso- and macropores, not penetrating into micropores. A modification of the microheterogeneous model under this assumption allows an adequate description of membrane conductivity and explains the fact that the membrane pore size increases with the duration of membrane utilization, while the apparent volume fraction of the inter-gel solution (f2app) decreases. CEMs are found less prone to fouling. The soaking of CEMs in the water-ethanol solution leads to an increase in IEC and f2app by 33% and 60%, respectively, as well as to doubling κm and decreasing θ by 23%, after a 120 h. treatment.

Membrane technologies, in particular, electrodialysis, are increasingly being used to stabilize and condition juices and wines. This work is aimed at finding environmentally appropriate “mild” methods for regeneration of anion-exchange membranes that are used in these processes. It has been shown that the fouling of anion-exchange membranes by grape wine components leads to an increase in both their electrical resistance by 30 or more times and thickness. The behavior of the resistance and its values in grape juice and wine for the investigated membranes are similar, apparently, due to the similar chemical composition of these liquid media. Treatment with NaCl solutions leads to partial degradation of the formed colloidal particles as a result of to the salting-out effect. The higher the salt concentration in the regenerating solution, the closer the conductivity values of the regenerated membranes are to the original values. The thinner the membrane and the larger its pores, the faster and more complete the regeneration process. If the contact time of anion-exchange membranes with wine does not exceed 70 h, salt regeneration can almost completely restore their selectivity. For example, in the case of homogeneous AMX-Sb membrane, the transport numbers of the counterion Cl− in the initial and regenerated samples differ by no more than 1%. In the case of heterogeneous MA-41P membrane, this difference increases to 3%.

Novel continuous-flow cascade reactions are developed for producing 1,4-diaryl-disubstituted dipolar γ-carbolines 2 that contain a carboxylate group and their two pentacyclic precursors 6, 7 from hemiindigos 1. The nucleophilic and pro-electrophilic chemistry described is new to the hemiindigos 1, and it led to the discovery of antimycobacterial scaffold characteristic of rimino-type pentacycles 6, 7 and potent drug clofazimine. The new scaffold like clofazimine appears to be useful in developing lead agents active against drug-resistant/dormant TB.

Swelling is an important property of charged gels and membranes. The size of pores and, therefore, membrane properties such as conductivity, diffusion and hydraulic permeability, permselectivity depend on water content and degree of swelling. In this paper we propose a simple model for equilibrium swelling of an ion-exchange membrane, allowing calculation of water content and membrane thickness as functions of the concentration and pH of the bathing solution. The model parameters include the equivalent volume of dry polyelectrolyte gel, the volume fraction of macropores and others. Three types of ion-exchange functional groups, namely, the secondary, tertiary and quaternary amino groups in an anion-exchange membrane are taken into account. The osmotic pressure exerted by micro- and mesopores, appearing in the gel when swelling, is expressed using the Gregor equation, which employs the mole fractions of free and bound water. The equilibria between protonated and deprotonated amino groups are assumed as well as the Donnan and ion-exchange equilibria between the membrane and bathing solution. The results of calculations are compared with experimental data on the membrane thickness and effective exchange capacity obtained for two heterogeneous anion-exchange membranes MA-40 and MA-41 (Shchekinoazot) differed by the composition of functional groups. The procedure of determining membrane structural and thermodynamic parameters is described. A good quantitative agreement between the theory and experiment is found for both membranes using the same set of ion hydration numbers and chemical equilibrium constants for secondary and tertiary amino groups. In particular, it is shown that with increasing pH of the bathing solution, the membrane thickness (and, hence, water content) pass through a local maximum and a local minimum. The simplicity of the model, which does not reduce adequacy, would enable it to be included later in other models describing the transport of ions and water to account for the swelling and change in the membrane structure with a change in pH and concentration of the bathing solution.

The use of reactive electrochemical membranes (REM) in flow-through mode during the anodic oxidation of organic compounds makes it possible to overcome the limitations of plate anodes: in the case of REM, the area of the electrochemically active surface is several orders of magnitude larger, and the delivery of organic compounds to the reaction zone is controlled by convective flow rather than diffusion. The main problem with REM is the formation of fouling and gas bubbles in the pores, which leads to a decrease in the efficiency of the process because the hydraulic resistance increases and the electrochemically active surface is shielded. This work aims to study the processes underlying the reduction in the efficiency of anodic oxidation, and in particular the formation of gas bubbles and the recharge of the REM pore surface at a current density exceeding the limiting kinetic value. We propose a simple one-dimensional non-stationary model of the transport of diluted species during the anodic oxidation of paracetamol using REM to describe the above effects. The processing of the experimental data was carried out. It was found that the absolute value of the zeta potential of the pore surface decreases with time, which leads to a decrease in the permeate flux due to a reduction in the electroosmotic flow. It was shown that in the solution that does not contain organic components, gas bubbles form faster and occupy a larger pore fraction than in the case of the presence of paracetamol, with an increase in the paracetamol concentration, the gas fraction decreases. This behavior is due to a decrease in the generation of oxygen during the recombination reaction of the hydroxyl radicals, which are consumed in the oxidation reaction of the organic compounds. Because the presence of bubbles increases the hydraulic resistance, the residence time of paracetamol—and consequently its degradation degree—increases, but the productivity goes down. The model has predictive power and, after simple calibration, can be used to predict the performance of REM anodic oxidation systems.

The interplay between the ion exchange capacity, water content and concentration dependences of conductivity, diffusion permeability, and counterion transport numbers (counterion permselectivity) of CJMA-3, CJMA-6 and CJMA-7 (Hefei Chemjoy Polymer Materials Co. Ltd., China) anion-exchange membranes (AEMs) is analyzed using the application of the microheterogeneous model to experimental data. The structure–properties relationship for these membranes is examined when they are bathed by NaCl and Na2SO4 solutions. These results are compared with the characteristics of the well-studied homogenous Neosepta AMX (ASTOM Corporation, Japan) and heterogeneous AMH-PES (Mega a.s., Czech Republic) anion-exchange membranes. It is found that the CJMA-6 membrane has the highest counterion permselectivity (chlorides, sulfates) among the CJMAED series membranes, very close to that of the AMX membrane. The CJMA-3 membrane has the transport characteristics close to the AMH-PES membrane. The CJMA-7 membrane has the lowest exchange capacity and the highest volume fraction of the intergel spaces filled with an equilibrium electroneutral solution. These properties predetermine the lowest counterion transport number in CJMA-7 among other investigated AEMs, which nevertheless does not fall below 0.87 even in 1.0 eq L−1 solutions of NaCl or Na2SO4. One of the reasons for the decrease in the permselectivity of CJMAED membranes is the extended macropores, which are localized at the ion-exchange material/reinforcing cloth boundaries. In relatively concentrated solutions, the electric current prefers to pass through these well-conductive but nonselective macropores rather than the highly selective but low-conductive elements of the gel phase. It is shown that the counterion permselectivity of the CJMA-7 membrane can be significantly improved by coating its surface with a dense homogeneous ion-exchange film.

Mycobacterium tuberculosis (Mtb) infection is among top ten causes of death worldwide, and the number of drug-resistant strains is increasing. The direct interception of human immune signaling molecules by Mtb remains elusive, limiting drug discovery. Oxysterols and secosteroids regulate both innate and adaptive immune responses. Here we report a functional, structural, and bioinformatics study of Mtb enzymes initiating cholesterol catabolism and demonstrated their interrelation with human immunity. We show that these enzymes metabolize human immune oxysterol messengers. Rv2266 - the most potent among them - can also metabolize vitamin D3 (VD3) derivatives. High-resolution structures show common patterns of sterols binding and reveal a site for oxidative attack during catalysis. Finally, we designed a compound that binds and inhibits three studied proteins. The compound shows activity against Mtb H37Rv residing in macrophages. Our findings contribute to molecular understanding of suppression of immunity and suggest that Mtb has its own transformation system resembling the human phase I drug-metabolizing system.

We report the study of commercially pure titanium (VТ1-0 alloy under Russian classification) in the submicrocrystalline state obtained by the abc-pressing method with the surface modified by the ion implantation technique. Ion implantation was performed using aluminum ions at irradiation doses 1 × 1017, 5 × 1017, and 10 × 1017 ion/cm2 using a MEVVA5.RU source. The grain longitudinal and transverse dimensions were determined before and after ion implantation for varying irradiation doses. We studied the influence of ion implantation and the irradiation dose on the elemental and phase composition of the surface layers of VT1-0 alloy. It has been found that ion implantation results in restructuring of titanium surface layers and in a change of the grain size with the depth of the surface layers. For example, the grain longitudinal size decreases 5 times at the dose rate of 1·1017 ion/cm2. It has been found that aluminum ion implantation modifies the surface layers containing intermetallic phases of TiAl3, Ti3Al, and aluminum and titanium oxides (Al2O3, TiO2, TiO и Ti2O3). Increasing the irradiation dose does not qualitatively change the alloy phase composition, but affects the quantitative characteristics of the formed secondary phases.

Transmission electron microscopy (TEM) investigations were carried out to study the structural-phase state of ultra-fine grained (UFG) titanium with the average grain size of ∼0.2 and 0.3 µm, implanted with aluminium ions. MEVVA-V.RU ion source was used for ion implantation under room temperature, exposure time of 5.25 h, at ion implantation dosage of 1×1018 ion/cm2. UFG-titanium was obtained by means of multiple uniaxial compacting with multipass rolling in grooved rolls and further annealing at 573 K during 1 hour to reach the average grain size of ∼0.2 µm, and annealing at 623 K during 1 hour to reach the size of ∼0.3 µm. The study revealed that in alloy with the average grain size of ∼0.2 µm implantation results in a decrease in longitudinal grain size of α-Ti (from 1.9 to 0.7 µm), however lateral size in its turn changed insignificantly (from 0.15 to 0.12 µm). Grain anisotropy factor decreased by 3 times. In the alloy with the average grain size of ∼0.3 µm both longitudinal and lateral grain sizes decreased (from 0.33 to 0.19 µm and from 2.1 to 0.8 µm correspondingly). The studies also showed that implantation of titanium with aluminium has led to the formation of a number of phases, such as: β-Ti, TiAl3, Ti3Al, TiC and TiO2. Their places of concentration, sizes, distribution density and volume ratios were determined. TiAl3 and Ti3Al phases were established to be ordered ones, formed within the conditions of ion exposure along the boundaries of α-Ti grains. Conducted calculations demonstrated that implantation contributed to the alloy strengthening, i.e. in alloy with the average grain size of ∼0.2 µm the value of yield stress increased by 2 times, and in the alloy with the average grain size of ∼0.3 µm—by 4 times.

Recently developed and produced by Hefei Chemjoy Polymer Material Co. Ltd., homogeneous CJMC-3 and CJMC-5 cation-exchange membranes (CJMCED) are characterized. The membrane conductivity in NaCl, Na2SO4, and CaCl2 solutions, permeability in respect to the NaCl and CaCl2 diffusion, transport numbers, current&ndash, voltage curves (CVC), and the difference in the pH (DpH) of the NaCl solution at the desalination compartment output and input are examined for these membranes in comparison with a well-studied commercial Neosepta CMX cation-exchange membrane produced by Astom Corporation, Japan. It is found that the conductivity, CVC (at relatively low voltages), and water splitting rate (characterized by DpH) for both CJMCED membranes are rather close to these characteristics for the CMX membrane. However, the diffusion permeability of the CJMCED membranes is significantly higher than that of the CMX membrane. This is due to the essentially more porous structure of the CJMCED membranes, the latter reduces the counterion permselectivity of these membranes, while allowing much easier transport of large ions, such as anthocyanins present in natural dyes of fruit and berry juices. The new membranes are promising for use in electrodialysis demineralization of brackish water and natural food solutions.

SummaryReliable delivery of presynaptic material, including active zone and synaptic vesicle proteins from neuronal somata to synaptic terminals is prerequisite for faithful synaptogenesis and neurotransmission. However, molecular mechanisms controlling the somatic assembly of presynaptic precursors remain insufficiently understood. Here we show that in mutants of the small GTPase RAB2 active zone and synaptic vesicle proteins accumulated in the neuronal somata at the trans-Golgi network and were consequently depleted at synaptic terminals, provoking neurotransmission deficits. The ectopic presynaptic material accumulations consisted of heterogeneous vesicles and short tubules of 40×60 nm and segregated in subfractions either positive for active zone proteins or co-positive for synaptic vesicle proteins and LAMP1, a lysosomal membrane protein. Genetically, rab2 behaved epistatic over arl8, a lysosomal adaptor controlling axonal export of precursors. Collectively, we here identified a Golgi-associated assembly sequence in presynaptic precursor vesicle biogenesis controlled by RAB2 dependent membrane remodelling and protein sorting at the trans-Golgi.

The effect of pH and concentration of the NaCl solution on the exchange capacity and transport properties of the MA-40 and MA-41 anion-exchange heterogeneous membranes with different nature of fixed groups has been studied: MA-40 has weakly basic groups, and MA-41 has strongly basic groups with a small proportion of weakly basic ones. The exchange capacity, thickness, water content, and electrical conductivity of the membranes equilibrated with NaCl solutions of various concentrations and pH were measured; for the same solutions, the diffusion permeability coefficients were found. The capacity was measured in the pH range from 1.5 to 12; the remaining properties, in the pH range from 3 to 9. Using the values of electrical conductivity and diffusion permeability, the ion transport numbers in the membranes were calculated. It was shown that at the external solution pH 9 the thickness of the membranes and their electric conductivity are minimal, and the transport numbers of co-ions are maximum. This is explained by the fact that in basic solutions weakly basic functional groups are largely deprotonated, and the effective capacity of the membrane is significantly reduced. The maximum effective capacity is achieved at pH $$ \leqslant $$ 3; in this case, transport numbers of co-ions in the MA-40 membrane are 5-fold, and in the MA-41 membrane, two-fold lower than corresponding values at pH 6 and 9. The changes in the transport properties of the membranes with increasing pH are due to a decrease in the degree of protonation of weakly basic functional groups, these changes are more pronounced for the MA-40 membrane than for MA-41.

Pulsed electric fields (PEF) have been used to advantage in electroplating for more than half a century. Recently, interest has increased in the application of these electric modes in the membrane processes. In this work, the effect of parameters (potential, frequency of current, and duty cycle) of pulsed current mode on the average current density in the electrodialysis cell is studied. For this purpose, the plots of current vs. time were measured in the mode of pulsed potential drop on a Nafion 438 (NafionTM N438) cation-exchange membrane. It is shown that the largest gain in the current density of 33% can be attained by varying parameters of PEF.

Current-voltage characteristics (CVCs) of a Neosepta AMX membrane are studied in NaH2PO4 (pH = 4.7, C = 0.02 mol/L) and KC4H5O6 (pH = 3.6, C = 0.02 mol/L) solutions. It is shown that in the case of NaH2PO4 there are two plateaus in the CVC, which correspond to achievement of the first, i lim I , and second, i lim I I , limiting currents. i lim I occurs when the NaH2PO4 salt diffusion to the membrane surface is saturated, i lim I I refers to the saturation of the proton flux when the membrane is almost completely converted into the HPO42− form. In the case of potassium hydrotartrate, there is no state corresponding to i lim I . The difference in CVC for two ampholytes is due to the difference in the ratio between the dissociation constants related to the first (Ka1) and second (Ka2) steps of ampholyte dissociation. In the case of NaH2PO4, where pKa1 and pKa2 differ greatly, a solution of this salt contains nearly exclusively the singly charged phosphate form. However, a KC4H5O6 solution contains, together with the C4H5O6− anion, about 15% of the doubly charged tartrates, which take part in charge transfer. Approximate analytical expressions are obtained for i lim I and i lim I I in the case of monosodium hydrophospate solution. Their application gives the i lim I and i lim I I values, which are in good agreement with the experiment and with numerical calculations using a mathematical model based on the Nernst-Planck equation, the electroneutrality condition, and the local chemical equilibrium condition in the membrane and two adjacent diffusion boundary layers.

A simple non-steady state mathematical model is proposed for the process of purification of an amino acid solution from mineral salts by the method of neutralization dialysis (ND), carried out in a circulating hydrodynamic mode. The model takes into account the characteristics of membranes (thickness, exchange capacity and electric conductivity) and solution (concentration and components nature) as well as the solution flow rate in dialyzer compartments. In contrast to the known models, the new model considers a local change in the ion concentration in membranes and the adjacent diffusion layers. In addition, the model takes into consideration the ability of the amino acid to enter the protonation/deprotonation reactions. A comparison of the results of simulations with experimental data allows us to conclude that the model adequately describes the ND of a strong electrolyte (NaCl) and amino acid (phenylalanine) mixture solutions in the case where the diffusion ability of amino acids in membranes is much less, than mineral salts. An example shows the application of the model to predict the fluxes of salt ions through ion exchange membranes as well as pH of the desalination solution at a higher than in experiments flow rate of solutions in ND dialyzer compartments.

The concentration dependencies of diffusion permeability of homogeneous (AMX-Sb and AX) and heterogeneous (MA-41 and FTAM-EDI) anion-exchange membranes (AEMs) is obtained in solutions of ampholytes (sodium bicarbonate, NaHCO3, monosodium phosphate, NaH2PO4, and potassium hydrogen tartrate, KHT) and a strong electrolyte (sodium chloride, NaCl). It is established that the diffusion permeability of AEMs increases with dilution of the ampholyte solutions, while it decreases in the case of the strong electrolyte solution. The factors causing the unusual form of concentration dependencies of AEMs in the ampholyte solutions are considered: (1) the enrichment of the internal AEM solution with multiply charged counterions and (2) the increase in the pore size of AEMs with dilution of the external solution. The enrichment of the internal solution of AEMs with multiply charged counterions is caused by the Donnan exclusion of protons, which are the products of protolysis reactions. The increase in the pore size is conditioned by the stretching of the elastic polymer matrix due to the penetration of strongly hydrated anions of carbonic, phosphoric, and tartaric acids into the AEMs.

Using the methods of electron diffraction microscopy and X-ray diffraction analysis, the influence of alloying of the austenitic steel, Grade 110H13, with chromium and vanadium, as well as high-melting, ultrafine-grained TiO2, ZrO2 powders and Na3AlF6 cryolite on its structural-phase state and microstructure is investigated. It is shown that the matrix of non-modified steel is completely austenitic and consists of an iron-based solid solution and the interstitial (C, N, O and other) and substitutional (Cr, V and other) atoms simultaneously. Alloying with chromium and vanadium changes neither its phase composition nor defect structure, while alloy modification results in qualitatively new structural features: γ → e-transformation, high-intensity microtwinning, defect structure changes, and a sharp increase in the scalar dislocation density. The features of the deformation-induced microtwinning and e-martensite plates identified in the modified steel promote revealing additional microtwin systems in the matrix γ-phase, which result in structural changes making it possible to classify it as a γ′-phase. It is found out that an introduction of modifying additions gives rise to the following sequence of structural-phase transformations: γ→γ′→(γ′ +e). The experimental data obtained demonstrate that as a result of modification the crystal lattice transits into a low-stability state. This transition is accompanied by marked structural-phase changes consisting in the formation of several microtwin systems and γ → e-transformation. These structural-phase changes in the modified steel are due to the crystal-lattice transition into the low-stability state, followed by new structural-phase alterations.