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The structure and electromagnetic properties of a lithium ferrite, Li0.5Fe2.5O4, fabricated by an additive manufacturing process based on extrusion printing of ferrite samples with a binder substance followed by hightemperature sintering are studied. A preliminary ferrite-powder synthesis is carried out by the solid-phase method using iron oxide and lithium carbonate. The ferrite paste for printing is prepared using a binder based on ethyl cellulose and terpineol. The samples measuring 100 and 500 μm are fabricated by extrusion in a Voltera V-one 3D printer. The samples are sintered in a laboratory furnace at 1100°C. The microstructure and properties of the resulting ferrites depend on the printed layer thickness. The samples are characterized by a relative density of 72 and 76%, a specific saturation magnetization of 50 and 62 emu/g, a Curie temperature of 625 and 630°C, and a specific electric resistivity of 1.1·1010 and 1.6·109 Ω·cm for the 100 and 500 μm-thick samples, respectively. [ABSTRACT FROM AUTHOR]

We calculate electronic structure and spin susceptibility dependencies on doping within the framework of a cluster perturbation theory for strongly correlated electronic systems. The change in the susceptibility with increasing doping is qualitatively consistent with the experimental data on resonant inelastic X-ray scattering and inelastic neutron scattering, as well as with the results of the calculations within the quantum Monte Carlo method. [ABSTRACT FROM AUTHOR]

A Hamiltonian decomposition of a regular graph is a partition of its edge set into Hamiltonian cycles. We consider the second Hamiltonian decomposition problem: for a 4-regular multigraph, find 2 edge-disjoint Hamiltonian cycles different from the given ones. This problem arises in polyhedral combinatorics as a sufficient condition for non-adjacency in the 1-skeleton of the traveling salesperson polytope. We introduce two integer linear programming models for the problem based on the classical Dantzig-Fulkerson-Johnson and Miller-Tucker-Zemlin formulations for the traveling salesperson problem. To enhance the performance on feasible problems, we supplement the algorithm with a variable neighborhood descent heuristic w.r.t. two neighborhood structures and a chain edge fixing procedure. Based on the computational experiments, the Dantzig-Fulkerson-Johnson formulation showed the best results on directed multigraphs, while on undirected multigraphs, the variable neighborhood descent heuristic was especially effective. [ABSTRACT FROM AUTHOR]

Separation of titanium and silicon oxides in the melt of quartz–leucoxene concentrate of the Yarega deposit under diffuse arc heating was investigated. Melting was carried out in argon at atmospheric pressure at direct current in a graphite crucible with an arc power of ≈25 kW. The crucible with the material was the anode of the arc. The arc heating was dispersed by applying an axial magnetic field. At the same time, a diffuse anode spot with a current density of 8 A/cm2 was formed on the surface of the material. The current–voltage parameters of the diffuse arc were investigated. As a result of melting, an oxide ingot consisting of two phases was obtained, one of which is enriched in titanium oxide, and the other in silicon oxide. However, the separation of these oxides did not occur completely because of the high cooling rate of the melt. Despite the low current density in the heating spot, the melt evaporated intensely. Evaporation occurred congruently. Owing to the high temperature of the bath mirror, no volatile titanium oxide evaporated along with the volatile silicon oxide. Condensation of the evaporated material occurred selectively. A condensate consisting almost entirely of SiO2 was formed in the form of powder on the cooled surfaces near the crucible. The specific surface area of the powder was 120 m2/g. The evaporated TiO2 was removed with the exhaust gas. [ABSTRACT FROM AUTHOR]

The surface treatment of single-crystal germanium with an argon cluster ion beam has been investigated. The original surface of the germanium wafers was bombarded with argon cluster ions with high (105 eV/atom) and low (10 eV/atom) specific energies. Using an atomic force microscope, images were obtained and a comparison of the surface topography before and after cluster ion bombardment was conducted. The smoothing of the surface was demonstrated using the power spectral density function of roughness in the range of spatial frequencies: 1) m —for the high-energy mode; 2) m —for the low-energy mode. [ABSTRACT FROM AUTHOR]

The effect of solvents similar in physical properties to water on the formation of a hydrate shell around lactose monohydrate molecules has been studied by terahertz spectroscopy in transmission mode. A relationship has been established between the concentration of aqueous solutions of lactose monohydrate and the thickness of its hydrate shell when dissolved in purified water, an aqueous solution of high dilution (HD) and an aqueous solution of high dilution with antibodies to interferon-gamma (HD Ab to IFNg). It was found that the solvent HD Ab to IFNg dissolves more lactose monohydrate molecules at the same volume compared to other studied solvents. [ABSTRACT FROM AUTHOR]

The influence of the structure of nickel-zinc ferrite powders on the behavior of magnetic phase transitions is studied in the Curie point region. The samples with a controlled set of microstresses and sizes of coherent scattering regions are prepared by dry milling of the synthesized ferrites in a ball mill at the rates of 500, 1000, 1500 rev/min for 15, 30, and 60 min. Their structure is examined by the method of X-ray diffraction. An analysis of the magnetic phase transitions in the Curie temperature region is performed using thermogravimetry in a constant magnetic field (thermomagnetometry). The regularities of variations of the powder structure parameters as a function of the frequency-time dry milling modes are identified. A linear regression dependence of the amplitude of the weight section in the thermogravimetry curve in the Curie point region on the value of microstresses and the size of coherent scattering regions is revealed. The findings allow taking account of the influence of these structural characteristics on the shape of the thermograms in the region of magnetic phase transitions and provide a more precise interpretation of the thermomagnetometric results. [ABSTRACT FROM AUTHOR]

The structural, electrical, and magnetic properties of lithium zinc ferrite prepared by ceramic technology have been studied. The composition of lithium zinc ferrite is Li0.4Fe2.4Zn0.2O4 with 1 and 2 wt % bismuth oxide. The addition of Bi2O3 prior to sintering of the samples has been shown to affect the structural, electrical, and magnetic properties of the ferrite. A significant increase in density from 4.47 to 4.65 g/cm3 and a decrease in porosity from 4.8 to 2.3% have been observed when the concentration of bismuth oxide has been increased to 2 wt %. The Bi2O3-containing samples have higher specific electrical resistivity compared to that of the additive-free lithium zinc ferrite. The introduction of bismuth oxide has reduced the specific saturation magnetization from 70.55 to 54.76 G cm3/g. The Curie temperature has not changed significantly. An optimal combination of macroscopic properties of ferrite has been found at 1 wt % Bi2O3 concentration. [ABSTRACT FROM AUTHOR]

The influence of the degree of dispersion of a nickel–zinc ferrite powder of a Ni0.7Zn0.3Fe2O4 composition on its magnetic properties has been considered. The material has been synthesized using the ceramic technology with preliminary mechanical activation of precursors. The degree of dispersion has been varied using different modes of its dry grinding in a ball mill. The patterns of the changes in saturation magnetization and the coercive force as a function of grinding modes and a specific surface area of the ferrite powder have been established. The changes in the pattern of the magnetic phase transition in the region of the Curie temperature of materials with different degrees of dispersion have been determined. [ABSTRACT FROM AUTHOR]

Thomson scattering of the core edge and divertor plasma regions of a tokamak with reactor technologies is discussed. The rationale and choice of technical solutions are given, the composition of the Thomson scattering diagnostic complex is discussed, as well as an estimate of the accuracy of measuring both electron temperature and density. Particular attention is paid to ensuring the functionality of the proposed diagnostics in the reactor mode of the tokamak operation and the results of testing diagnostic equipment in the experiments on Globus-M2 tokamak. [ABSTRACT FROM AUTHOR]

The features of the surface treatment of potassium-gadolinium-tungstate single crystals doped with neodymium ions by low- and high-energy argon cluster ions are considered. Two radically different treatment modes are employed: the low-energy mode for more efficient smoothing of the surface and high-energy for more effective etching of the target. The topography of the target surface is analyzed before and after cluster-ion treatment using atomic force microscopy. It is shown that treatment in the low-energy mode smoothes out irregularities on the target surface formed by chemical and mechanical polishing at an etching depth of less than 100 nm. A comparison is made of the root-mean-square roughness and total roughness of the initial and treated surfaces of potassium-gadolinium tungstate doped with neodymium ions. Survey X-ray photoelectron spectra of the initial surface of a KGd(WO4)2:Nd single crystal and after cluster-ion treatment in various modes are presented. It is demonstrated that the intensities of the potassium and gadolinium peaks decrease after cluster-ion treatment in both modes. A significant decrease in the concentration of potassium atoms in the surface layer of the target is explained by the preferential sputtering of potassium as a lighter chemical element. The mutual decrease in the concentrations of gadolinium and potassium atoms can be explained by the weak bonds of these atoms in the lattice of the KGd(WO4)2:Nd single crystal. [ABSTRACT FROM AUTHOR]

The authors study the effect the dispersion of particles of synthesized nickel–zinc ferrite powder has on its structural and magnetic properties. Ferrite powder is fabricated using ceramic technology. The average particle size is varied by means of mechanical activation. The patterns of the formation of nickel–zinc ferrite's properties are established via X-ray diffraction analysis, laser diffraction, and thermal analysis, depending on the modes of mechanical activation. [ABSTRACT FROM AUTHOR]

A dimeric dipeptide mimetic based on the β-turn of the 4th loop of neurotrophin-3, bis-(N-monosuccinyl-L-asparaginyl-L-asparagine)hexamethylenediamide (GTS-301LL), was recently designed and synthesized by us. GTS-301, like the full-length neurotrophin, activated TrkC and TrkB receptors and exhibited neuroprotective activity on HT22 cells under oxidative stress conditions in the concentration range 10–5 – 10–12 M and antidepressant-like activity in the forced swimming test in mice (10 – 40 mg/kg, intraperitoneally). The stereospecificity of the pharmacological effects of GTS-301LL was revealed by synthesizing the LD, DL, and DD stereoisomers of GTS-301LL and studying their neuroprotective and antidepressant-like properties under the same conditions as for GTS-301LL. Both activities were found to disappear on going from the LL to the DL and DD stereoisomers and were retained on going to the LD stereoisomer. Thus, the stereospecificity of the neuroprotective and antidepressant-like activities of the dipeptide mimetic of neurotrophin-3 GTS-301LL at the N-terminal asparagine residue was proven, which indicated the key role of that amino-acid residue in the interaction with the receptor. [ABSTRACT FROM AUTHOR]

Nonlinear phenomena similar to the Belousov–Zhabotinsky reaction (autocatalytic oscillations of the population of high-spin and low-spin multielectron states of a transition metal ion) in open systems with spin crossover near bistability are considered. The conditions for possible experimental observation of autocatalytic oscillations of the magnetization in magnetically ordered systems with spin crossover are analyzed. [ABSTRACT FROM AUTHOR]

A technique is proposed for determining the temperature of a laser diode operating in a continuous mode, as well as thermal resistance of the device by comparing its current-voltage characteristic with pulsed current-voltage characteristics measured at different temperatures. The technique was applied to a ∅200 μm half-disk microlaser with an active region based on InGaAs/GaAs quantum dots. It was found that at currents corresponding to the peak laser power and lasing quenching due to overheating of the active region, the device temperature reaches 101 and 149°C, respectively. The thermal resistance of the laser is 110 K/W. [ABSTRACT FROM AUTHOR]

An approximation of the turbulent moments of the atmospheric convective layer is based on a variant of the local similarity theory using the concepts of the semiempirical theory of Prandtl turbulence. In the proposed variant of the local similarity theory, the second moment of vertical velocity and the "spectral" Prandtl mixing length are used as basic parameters. This approach allows us to extend Prandtl's theory to turbulent moments of vertical velocity and buoyancy and additionally offer more than ten new approximations. A comparison of the proposed approximation with other variants of the theory of local similarity is considered. It is shown that the selected basic parameters significantly improve the agreement between the local similarity approximations and experimental data. The approximations are consistent with observations in the turbulent convective layer of the atmosphere, the upper boundary of which nearly corresponds to the lower boundary of the temperature inversion. Analytical approximations of local similarity can find applications in the construction of high-order moment closures in the vortex of resolving numerical turbulence models, as well as in the construction of "mass-flux" parametrization. [ABSTRACT FROM AUTHOR]

A nonlinear integral equation arising from a parametric closure of the third spatial moment in the single-species model of logistic dynamics of U. Dieckmann and R. Law is analyzed. The case of piecewise constant kernels is studied, which is important for further computer modeling. Sufficient conditions are found that guarantee the existence of a nontrivial solution to the equilibrium equation. The use of constant kernels makes it possible to obtain more accurate results compared to earlier works, in particular, more accurate estimates for the L1 norm of the solution and for the closure parameter are obtained. [ABSTRACT FROM AUTHOR]

The mine shafts in the salt (unwatered) rock mass at the Upper Kama deposit are mostly lined with cast-in-place concrete and reinforced concrete, which should ensure the required load-bearing capacity and water impermeability in host rocks in creep. The long-term observations of the shaft lining in operation revealed some typical patterns of failure induced by the rheological properties of salt rock mass under the action of rock pressure. The technical evaluation of the lining and reinforcement of mine shafts is an integrated checkup procedure including measurements of fractures and areas of corrosive zones/rock falls; updating of actual geometrics of lining from laser measurements; determination of residual strength of lining; mathematical modeling; estimation of integral reliability index of lining. The authors propose a procedure to categorize technical conditions of concrete lining in mine shafts in operation in salt-bearing rock mass in creep. The application of the procedure is described, and the conclusions on the package of repair activities are drawn. [ABSTRACT FROM AUTHOR]

Our recent work on multiple locations of boron atoms in the exohedral and endohedral C60 fullerene, [1], carried out within the Hartree-Fock method with the second order Møller-Plesset perturbation theory MP2 (HF-MP2), prompted recently a comment from Xu and Hou, [2], who have performed several density functional theory (DFT) calculations using DFT functionals of different complexity. In three out of five cases considered in our work, DFT calculations give the same ground state confirmations whereas in two cases optimal configurations have turned out to be different. However, depending on the choice of the exchange-correlation functional, the geometry optimization within DFT can also result in different ground state confirmations. The energy balance between nearest confirmations in these molecular complexes is subtle, and various methods can give different ground state structures. We therefore argue that the presented DFT calculations are not benchmark, and their results should be compared with ours (HF-MP2) on equal ground. We also present additional HF geometry optimizations with the 6-31G* basis set, which confirm the ground state confirmations obtained at the HF/6-31G level. [ABSTRACT FROM AUTHOR]

Analytical expressions for spontaneous emission probability in the vicinity of nanowire for the emitter oriented in axial, radial and azimuthal direction in respect to the nanowire axis, has been obtained. Directionality of emission and probability of emission have been calculated for various positions of emitter. Enhancement of the spontaneous emission probability by one order of magnitude, and formation of the sharp directionality diagram has been demonstrated. [ABSTRACT FROM AUTHOR]

An avalanche silicon photodiode has been developed for the near IR, visible, UV and VUV light ranges. The external quantum efficiency has been studied in the 114–170 and 210–1100 nm ranges. It has been demonstrated that the avalanche photodiode reaches the quantum yield of 29 to 9300 electrons/photon at the 160 nm wavelength and bias voltage of 190–303 V, respectively. [ABSTRACT FROM AUTHOR]

Record thick (up to 100 μm) epitaxial layers of a prospective metastable semiconductor Ga2O3 were grown by HVPE (Halide Vapor Phase Epitaxy) on GaN buffer layers on c-sapphire substrates. The X-ray diffraction pattern of the layers show that the structure of the layer is a pure κ(ε)-Ga2O3 without any other phases. At the same time, the organization of a domain structure was observed, which manifests itself in the form of pseudohexagonal prisms that retain the orientation of the gallium nitride sublayer. Schottky diodes with nickel contacts were fabricated and the electrical and photoelectric properties of the layers were studied. Capacitance–voltage (C–V) and frequency–capacitance (C–f) dependencies were studied, photocurrent and photocapacitance spectra were measured. [ABSTRACT FROM AUTHOR]

The possibility to increase the responsivity of 4H-SiC p+–n–n+-photodiodes by varying the thickness of the p+-epilayer has been studied. It is shown that the thinning of the upper epilayer by RIE with the use of metal contacts as a mask makes it possible to control both the maximum responsivity and the spectral dependence of the responsivity of photodiodes and does not lead to degradation of dark electrical characteristics. [ABSTRACT FROM AUTHOR]

A magnetoelectric effect, which manifests itself as a "refraction" of domain walls at the location of an electrode deposited on the surface of an iron garnet film, is studied. The "refractive index" depends on the electric voltage applied to the electrode and varies from 0.6 to 1.2. An electrically induced change in the surface energy of a domain wall due to an inhomogeneous magnetoelectric coupling is suggested as the mechanism of this effect. [ABSTRACT FROM AUTHOR]

The interaction of plasmonic whispering gallery modes on the surface of silver nanospheres with an exciton of the surrounding organic medium has been theoretically studied. DPAVBi (4,4'-bis[4-(di-ptolylamino) styryl]biphenyl) was selected as an organic material due to its high oscillator strength. The results show that for spheres of sufficiently large radii, several plasmon modes can be localized on their surface at once, which makes them possible for strong coupling with an exciton. The calculated spectra confirm that plasmon modes can effectively interact with excitons in the surrounding organic material, which leads to a significant change in both the absorption and emission characteristics of the system. These observations highlight the potential of such hybrid systems for a number of applications in optoelectronics and photonics, making them a promising platform for further research in this area. [ABSTRACT FROM AUTHOR]

The paper presents a procedure for creating on GaAs(100) substrates textured surfaces by ion-beam etching with a focused beam. The possibility of flexibly controlling the shape and profile of the formed submicron elements of textured media is shown; this will later allow formation of textured surfaces of almost any complexity for realizing the surface radiation coupling from the waveguide. Original lithographic masks were developed, and 3D lithography was accomplished. The obtained lithographic patterns were controlled by the methods of optical, electron and atomic force microscopy. [ABSTRACT FROM AUTHOR]

A new mechanism of the photoinduced enhancement of the excitonic order in strongly correlated electron systems with the spin crossover through the generation of a massive mode in the spectrum of collective excitations is demonstrated. [ABSTRACT FROM AUTHOR]

The preparation of synthetic rutile by selective evaporation of silicon oxide from quartz leucoxene of the Yaregskoe deposit during plasma arc melting is investigated. The melting is conducted under atmospheric pressure by a 9–16 kW arc discharge of direct polarity in a laboratory furnace. There are the two variants of melting: by a diffuse arc with a distributed heating spot and by a contracted arc with a high heat flux density. The contracted arc causes intense evaporation of material. The rate of evaporation with a contracted arc is approximately ten times higher than the rate of evaporation with a diffuse arc, but the energy consumption of the former is ten times less than that of the latter. The products of contracted arc evaporation contain a high amount of Ti, while Ti is practically absent in the products of diffuse arc evaporation. The evaporation with a diffuse arc is recommended for industrial application. The bath diameter should be equal to the diameter of the anode spot of the arc. This diameter is directly proportional to the furnace power for industrial furnaces. For example, the diameter for power P = 5 MW is da ≈ 5 m. Energy consumption pg for evaporation decreases when the furnace power increases. For P = 5 MW, pg = 14.5 GJ per 1 t of evaporated SiO2. The total energy consumption for the production of rutile is pΣ = 26 GJ/t. [ABSTRACT FROM AUTHOR]

Features of the formation of the magnetic structure and the exciton Bose–Einstein condensate phase of magnetic excitons in strongly correlated systems near the spin crossover have been considered with the effective Hamiltonian obtained from the two-band Hubbard–Kanamori model. The coexistence of antiferromagnetism and exciton condensate, as well as the appearance of the long-range excitonic antiferromagnetic order even in the absence of the interatomic exchange interaction, has been revealed. The role of the electron–phonon coupling has been considered. [ABSTRACT FROM AUTHOR]

It is proved that the rank of an elliptic curve is one less the arithmetic complexity of the corresponding non-commutative torus. As an illustration, we consider a family of elliptic curves with complex multiplication. [ABSTRACT FROM AUTHOR]

Abstract—The effect of 2-h annealing at temperatures of 180–300°C on the mechanical tensile behavior of a copper/aluminum D16 alloy composite prepared by cold rotary forging of an blank 20 mm in diameter to an blank 5 and 2.5 mm in diameter (e = 2.77 and 4.16, respectively) is studied. For comparison, a composite, which comprises additional 12Kh18N10T steel fibers longitudinally arranged between a sheath and a rod, is considered. Acoustic emission testing is used to study the deformation and failure processes of composite samples during uniaxial tension. The mechanical properties and deformation of the copper–aluminum composites are found to depend on the assembling and degree of reduction of area during rotary forging. The mechanical properties of the copper/aluminum alloy composite are less sensitive to heating as compared to those of the copper/steel/aluminum alloy composite. Annealing at 300°C causes the most substantial softening of the composite samples. [ABSTRACT FROM AUTHOR]

TrkA and TrkB knockout HT-22 cell lines were used to prove that the neuroprotective properties of GK-2 [bis(N-monosuccinyl-L-glutamyl-L-lysine hexamethylenediamide], a low-molecular-weight dipeptide mimetic of the NGF 4th loop, are definitely mediated by selective interaction with TrkA receptor upon oxidative stress-induced cellular damage in vitro. [ABSTRACT FROM AUTHOR]

The effect of mechanical activation of the mixture of Fe2O3-Co3O4-ZnO reagents on thermal synthesis of cobalt-zinc ferrite (Co0.5Zn0.5Fe2O4) was studied using X-ray powder diffraction and thermal analyses. The initial oxide powders were mixed using a Retsch Emax high energy ball mill to homogenize the mixture and enhance the reactivity. Mechanical activation was performed in air for 30 and 60 min. Thermal synthesis was performed at 900 °C for 4 h. X-ray diffraction analysis revealed an increase in the intensity of reflections that belong to spinel phases at increased rotational speed of the grinding vials and grinding duration. The patterns of formation of the final ferrite phase depending on the modes of mechanical pre-activation were showed by thermal analysis. It was shown that mechanical pre-activation of a mixture of initial reagents in a high-energy ball mill facilitates the formation of the ferrite phase of the given composition. The Curie temperature was determined for Co0.5Zn0.5Fe2O4 ferrite (~ 178 °C) by thermal synthesis. Kindly check and confirm whether the corresponding author is correctly identified. Corresponding author identified correctl [ABSTRACT FROM AUTHOR]

The paper addresses the study of the effect of different milling modes on the reactivity of the initial α-Fe2O3 and Li2CO3 powders by thermogravimetry and differential scanning calorimetry to obtain lithium ferrite of Li0.5Fe2.5O4 chemical composition. The formation of the magnetic phase of ferrite was monitored by thermogravimetric analysis in a magnetic field. The powder mixture was mechanically activated in air at different processing time and vial rotation speed using a planetary mill. It was found that the reactivity of the initial reagents depends on milling energy intensity. A varied milling mode changes the pattern of the interaction between reagents, and therefore a temperature range, the number of stages and the rate of lithium ferrite formation. In these conditions, an increased vial rotation speed during milling makes a more significant contribution to the change in the powder reactivity as compared to longer milling time. [ABSTRACT FROM AUTHOR]

Formation of substituted lithium ferrite Li0.5SmxFe2.5–xO4 (where x = 0.06 and 0.2) from Sm2O3/Fe2O3/Li2CO2 precursors was studied by X-ray diffraction analysis, thermogravimetry, differential scanning calorimetry, and scanning electron microscopy. The mixture of powders was subjected to preliminary mechanical activation in a planetary mill. We analyzed samples based on the precursors and synthesized at 900 °C for 4 h in a laboratory furnace. It was found that ball milling of the precursors mixture in a planetary mill increases the powder reactivity. In spite of this, no substituted lithium ferrites were formed. It was shown that a two-phase composite that consists of pure lithium ferrite Li0.5Fe2.5O4 and SmFeO3 is formed during synthesis. An increase in the Sm2O3 content in the initial mixture provides an increase in the amount of the formed SmFeO3 phase. The synthesis of Li0.5Fe2.5O4 ferrite was confirmed by XRD analysis data, the Curie temperature (627–630 °C) measured using TG analysis in a magnetic field, and by the presence of an endothermic peak on the DSC curve corresponding to the order–disorder transition in the Li0.5Fe2.5O4 phase. [ABSTRACT FROM AUTHOR]

The effect of mechanical activation of the synthesized ferrite powder on the process of thermal sintering of ferrite ceramics has been studied. Mechanical activation of the powder of Li0.65Fe1.6Ti0.5Zn0.2Mn0.05O4 composition was performed at a drum rotation speed of 300, 600, and 1100 rpm using steel balls with a diameter of 2 and 5 mm. The mechanically activated powder was sintered in a highly sensitive dilatometer at 1010 °C for 2 h. Dilatometric analysis showed that the total shrinkage of the samples during sintering increases at increased energy intensity of ferrite powder milling. It was found that the sample prepared from the powder mechanically activated with 2 mm balls shows the best degree of complete compaction after sintering as compared with the samples activated using 5 mm balls. Shrinkage curves were used for kinetic analysis based on mathematical modeling to determine the parameters of ferrite sintering. Kinetic analysis showed that diffusion models are best suited for modeling the sintering process. [ABSTRACT FROM AUTHOR]

Accelerated cluster ions formed during the outflow of inert gases are a unique tool for the precision surface treatment of various materials, including nonlinear optical single crystals. However, the interaction of gas cluster ions with the surface of nonlinear single crystals has been little studied. In this paper, we consider the features of the formation of anomalous craters during treatment of the surface of hygroscopic lithium-triborate single crystals with argon cluster ions at various bombardment doses. The treatment is carried out at a kinetic energy of clusters of 22 keV, an average cluster size of about 210 atoms per cluster at a normal angle of incidence. It is shown that the anomalous craters have a diameter of 150 to 820 nm, which are two orders of magnitude larger than the diameter of ordinary impact craters. The depth of the craters varies from 5 to 9 nm. Such craters are formed at a target etching depth of up to 320 nm. A statistical analysis of the geometrical parameters of anomalous craters is carried out at various treatment doses. It is established that with an increase in the irradiation dose and, accordingly, the etching depth, the density of anomalous craters per unit surface of the target decreases, while their depth and average diameter increase significantly. [ABSTRACT FROM AUTHOR]

We study geometry of the ring of integers O K of a number field K. Namely, it is proved that the inclusion Z ⊂ O K defines a covering of the Riemann sphere C P 1 ramified over the points { 0 , 1 , ∞ } . Our approach is based on the notion of a Serre C ∗ -algebra. As an application, a new proof of the Belyi Theorem is given. [ABSTRACT FROM AUTHOR]

When the strength of light–matter interaction (the Rabi splitting) in mesocavities is comparable to the energy spacing between the cavity modes, an exciton mode is coupled simultaneously to a number of optical modes. It has recently been demonstrated that a nonmonotonic dependence of the population of polariton states in mesocavities on the pump intensity is possible. Here, it is shown that an additional quasistationary state may appear in the hysteresis region and the time spent by the system in this state depends on the pump intensity. [ABSTRACT FROM AUTHOR]

Crystalline neon film was condensed on a gold surface and reflected electron energy-loss spectra (REELS) was measured at the temperature of 5 K. Also face-centered-cubic (FCC) Ne was investigated theoretically using density-functional theory (DFT), GW approximation, random-phase approximation (RPA) and the Bethe–Salpeter equation (BSE). REELS was calculated in the independent particles level, and including many-body perturbation effects – appearance of the electron-hole pairs (e–h), local-field dielectric screening and excitons. Calculated electronic bandgap is 21.5 eV. Analyzing obtained theoretical and experimental REELS we conclude that first excitonic peak appears at 17.8 eV and all the peaks up to 21.5 eV are purely excitonic. Solid neon film, being a wide-gap dielectric, considered as promising material for implanting Th and studying its low-lying nuclear transition at 8.2 eV. [ABSTRACT FROM AUTHOR]

The robotic machine implementing the additive manufacturing of induction coils has been developed to typify and automate the manufacturing process of induction coils being a finished functional element of the antenna equipment. This manufacturing equipment makes it possible to mass-produce the high-power integral induction coils with a high repeatability of electrodynamic characteristics. [ABSTRACT FROM AUTHOR]

We consider a Hamiltonian decomposition problem of partitioning a regular graph into edge-disjoint Hamiltonian cycles. It is known that verifying vertex non-adjacency in the 1-skeleton of the symmetric and asymmetric traveling salesperson polytopes is NP-complete. On the other hand, a sufficient condition for two vertices to be non-adjacent can be formulated as a combinatorial problem of finding a second Hamiltonian decomposition of a 4-regular multigraph. We present two backtracking algorithms for constructing a second Hamiltonian decomposition and verifying vertex non-adjacency: an algorithm based on a simple path extension and an algorithm based on the chain edge fixing procedure.Based on the results of computational experiments for undirected multigraphs, both backtracking algorithms lost to the known general variable neighborhood search heuristics. However, for directed multigraphs, the algorithm based on chain fixing of edges showed results comparable to heuristics on instances with an existing solution and better results on infeasible instances where the Hamiltonian decomposition does not exist. [ABSTRACT FROM AUTHOR]

A detailed theoretical review of phase retrieval algorithms, including the generalized Gerchberg–Saxton algorithm and some of its modifications, is presented. The possibility of applying phase retrieval algorithms to study the magnetic domain structure by dichroic coherent diffractive imaging is investigated on numerical examples. An optimal strategy for analyzing experimental data, stable to their nonidealities, is developed. [ABSTRACT FROM AUTHOR]

In this paper, we analyze a system of nonlinear integral equations resulting from the three-parameter closure of the third spatial moments in the logistic dynamics model of U. Dieckmann and R. Law in the multi-species case. Specifically, the conditions under which the solution of this system is stable with respect to the closure parameters are investigated. To do this, the initial system of equations is represented as a single operator equation in a special Banach space, after which the generalized fixed point principle is applied. [ABSTRACT FROM AUTHOR]

Determination of national goals for achieving a land degradation neutrality (LDN) and the creation of systems of indicators for monitoring is an important strategic task for combating desertification and preventing land degradation in Turkmenistan, due to the implementation of target 15.3 of the UN Sustainable Development Goals for the period up to 2030. This paper analyzes the possibility of integrating global indicators of the LDN into the National System for Land Monitoring of Turkmenistan, which is currently being developed, and provides statistical and geoinformation data for the entire territory of the country. It has been found that, despite the new important data obtained using global approaches, reliable monitoring of the LDN based on national data is not fully feasible at present due to the fact that global indicators are not sufficiently confirmed by the available national data and do not correspond to global proxy indicators of dynamics of land cover, productivity, and stocks of soil organic carbon. This article proposes a working list of national analogue indicators and ways to validate them, as well as options for using lists of land use types to compile a matrix of negative and positive transitions with changes in land cover. It is recommended to use cartographic and fund data collected and processed in the late 1980s–90s as a "baseline" for monitoring land degradation, as well as materials on the assessment of the state of specially protected natural areas. Additional and alternative indicators of the LDN, which are of particular importance for Turkmenistan: salinization of soils and lands, soil deflation, climate aridity, and dust storms, are proposed. [ABSTRACT FROM AUTHOR]

The problems of the creation of vibroacoustic protection for ship equipment are presented. Mathematical models for evaluating the efficiency in terms of vibration power and of damping fasteners of the marine vibroactive mechanisms aimed at training the developed neural network system classifying the marine targets are given. [ABSTRACT FROM AUTHOR]

Previously, we have shown that the endogenous neuropeptide cycloprolylglycine (CPG) is the positive modulator of AMPA receptors and revealed the dependence of its anxiolytic and antihypoxic action on BDNF/Trk signaling. In the present work, we for the first time conducted in vitro experiments using the AMPA receptor blockers DNQX and GYKI 52466 and the Trk receptor blocker K252a. It is shown that the neuroprotective effect of CPG depends on the activation of both AMPA and Trk receptors. [ABSTRACT FROM AUTHOR]

The interaction of gas cluster projectiles with the surface of the inorganic compounds is still not a fully understood issue. To clarify the features of silica surface sputtering by noble gas cluster projectiles of various species at normal and oblique incidences, molecular dynamics simulations are employed. The impacts of the Ne, Ar, and Kr clusters with the sizes N of 561 and 923 atoms and scaled kinetic energy E/N from 10 to 140 eV/atom are compared. It is found that the projectile energy per impact area unit E/S and per mass unit of cluster E/M are generalizing parameters of the sputtering efficiency of material in the form of scaled yield Y. The preferential sputtering of oxygen atoms is more sensitive to gas cluster species at normal incidence and decreases significantly with increasing projectile energy E/N. The regularities of the redistribution of the initial kinetic energy of projectiles between the scattered cluster atoms, ejected target atoms, and the target are revealed under the various impact conditions. [ABSTRACT FROM AUTHOR]

This article is dedicated to an analysis of the background, modern practice, and the likely consequences of the measures taken by the United States to monopolize the global markets of space products, which today can be considered as a new global challenge to humanity. It is concluded that the bilateral Artemis Accords, initiated in 2020 with the declared purpose of exploring the circumlunar space and the Moon itself under the leading role of the United States, have features of a future transnational space megacartel. The largest, primarily American, companies that are already working on the creation of the main elements of the program for the commercial exploration of the Moon may become participants in this megacartel. As an optimal response from Russia to the monopolization of the global space economy, the authors propose the development of an integrative model of the space economy. Such a model should combine both measures to develop competition among national entities of the domestic markets of space products and steps towards concentrating the efforts of all interested economic entities to achieve the maximum competitiveness of Russia and Russian companies in the global markets. The necessity of forming an international legal basis for combating cartels in the markets of space goods is substantiated, including the development of measures to counter the monopolization of global space markets and the establishment of control over outer space and celestial bodies. [ABSTRACT FROM AUTHOR]