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Polar Rashba-type semiconductor BiTeI doped with magnetic elements constitutes one of the most promising platforms for the future development of spintronics and quantum computing thanks to the combination of strong spin-orbit coupling and internal ferromagnetic ordering. The latter originates from magnetic impurities and is able to open an energy gap at the Kramers point (KP gap) of the Rashba bands. In the current work using angle-resolved photoemission spectroscopy (ARPES) we show that the KP gap depends non-monotonically on the doping level in case of V-doped BiTeI. We observe that the gap increases with V concentration until it reaches 3% and then starts to mitigate. Moreover, we find that the saturation magnetisation of samples under applied magnetic field studied by superconducting quantum interference device (SQUID) magnetometer has a similar behaviour with the doping level. Theoretical analysis shows that the non-monotonic behavior can be explained by the increase of antiferromagnetic coupled atoms of magnetic impurity above a certain doping level. This leads to the reduction of the total magnetic moment in the domains and thus to the mitigation of the KP gap as observed in the experiment. These findings provide further insight in the creation of internal magnetic ordering and consequent KP gap opening in magnetically-doped Rashba-type semiconductors.

Several samples of nano-oil with different concentrations of dielectric and conductive nanoparticles are prepared to describe the electrophysical characteristics of nanofluids. Permittivity and conductivity of the nanofluids are experimentally measured. The processed experimental results are compared with the calculated results obtained using the Nielsen formula. The comparative analysis shows qualitative agreement of the calculated and experimental values of permittivity and a significant difference between the experimental and calculated dependences of conductivity on the concentration of particles. Such a difference between the calculated and experimental results is due to the adsorption of ions on the surface of the particles and their subsequent sedimentation. A decrease in the conductivity can be due to a decrease in the number of mobile particles and the fact that they have significantly less mobility compared to ions in the presence of weak electric fields. Additional measurements of the conductivity of nanofluids with particles of silicon dioxide and added oleic acid reproduce the observed decrease in the conductivity.

A new kind of magnetically-doped antiferromagnetic (AFM) topological insulators (TIs) with stoichiometry Bi 1.09 Gd 0.06 Sb 0.85 Te 3 has been studied by angle-resolved photoemission spectroscopy (ARPES), superconducting magnetometry (SQUID) and X-ray magnetic circular dichroism (XMCD) with analysis of its electronic structure and surface-derived magnetic properties at different temperatures. This TI is characterized by the location of the Dirac gap at the Fermi level (E F ) and a bulk AFM coupling below the Neel temperature (4–8 K). At temperatures higher than the bulk AFM/PM transition, a surface magnetic layer is proposed to develop, where the coupling between the magnetic moments located at magnetic impurities (Gd) is mediated by the Topological Surface State (TSS) via surface Dirac-fermion-mediated magnetic coupling. This hypothesis is supported by a gap opening at the Dirac point (DP) indicated by the surface-sensitive ARPES, a weak hysteresis loop measured by SQUID at temperatures between 30 and 100 K, XMCD measurements demonstrating a surface magnetic moment at 70 K and a temperature dependence of the electrical resistance exhibiting a mid-gap semiconducting behavior up to temperatures of 100–130 K, which correlates with the temperature dependence of the surface magnetization and confirms the conclusion that only TSS are located at the E F . The increase of the TSS’s spectral weight during resonant ARPES at a photon energy corresponding to the Gd 4 d -4 f edge support the hypothesis of a magnetic coupling between the Gd ions via the TSS and corresponding magnetic moment transfer at elevated temperatures. Finally, the observed out-of-plane and in-plane magnetization induced by synchrotron radiation (SR) due to non-equal depopulation of the TSS with opposite momentum, as seen through change in the Dirac gap value and the k ∥ -shift of the Dirac cone (DC) states, can be an indicator of the modification of the surface magnetic coupling mediated by the TSS.

In order to ensure high wear resistance of parts and tools, operating at significant dynamic loads in the extreme conditions, the layers different in their function purpose obtained using surfacing methods are widely used. In such surfacing compositions, the powders of high-melting compounds characterized by high hardness and strength, are used as a wear resistant component, for example, alloys of tungsten carbide WC + W2C (cast tungsten carbide), and as binder matrix the plastic and metal alloys are used.The great interest is the development of methods allowing producing powders of cast tungsten carbide and other high-melting-point materials of uniform composition, characterized by a high sphericity of the particles and having higher physical-mechanical properties. The spherical tungsten carbide was produced by plasma atomization of rotating billet. The universal installation for production of super-hard spherical tungsten carbide and other high-melting-point compounds by plasma atomization of rotating billets was designed for industrial application. The results showed that the application of the technology of plasma rotary atomization of rotation billet to obtain granules of powders of high-melting-point materials was promising, in particular tungsten carbide with sphericity over 90%, microhardness HV0.1 more than 3000 kg / mm2 characterized by high flow ability more than 7.5 s/ 50 g. Due to the use of new materials and innovative design and technological solutions the high reliability, maximum interval of technical service, high resource of operating units and executing mechanism of the equipment were ensured. Due to the use of new high-power plasma system with power supply source with high efficiency coefficient and improved dynamic characteristics, the system of preliminary heating of billets, innovative gas systems, high performance vacuum system, the developed universal system for the production of granules of powders of high-melting-point material were also applicable for the manufacture of spherical powders of metals and alloys, including highly active, and provided lower costs of products (powder) with an increased productivity, economic efficiency of the atomization process and reduced the impact of atomization process on the environment.

The temperature dependences of the heat capacity were measured and the general patterns of the formation of the phonon spectrum of single crystals of solid solutions of yttrium-lutetium aluminum garnets Y 3 – x Lu x Al 5 O 12 at 0 ≤ x ≤ 3 were investigated in the temperature range from 1.9 to 220 K. According to the data obtained at temperatures below 10 K, the Debye temperatures were calculated. The features of the phonon spectrum in the intermediate temperature range are interpreted as a superposition of optical modes for yttrium and lutetium garnets. It is shown that the low heat capacity values due to the contribution of acoustic phonons for Y 2.25 Lu 0.75 Al 5 O 12 correlate with anomalies in the concentration dependences of the phonon transport, the absorption of acoustic waves, and the shape of the aluminum NMR line.

In this paper, an attempt to evaluate the effect of particles on the electrical conductivity of liquid dielectrics is made. For this purpose, a conductivity model is formulated taking into account the presence of relatively large charged microparticles in the dielectric. Based on calculations using the model, a comparative assessment of electrical conductivity was carried out. It is shown that in sufficient quantities, particles can significantly increase the electrical conductivity when forming double electric layers near their surface.

The article considers the issue of protecting substation equipment and overhead lines from high-frequency lightning surges using a device based on a nanocrystalline tape made of an amorphizing ferromagnetic alloy. The object of protection is a substation that uses a cable insert between the overhead line and the substation input. A distinctive feature is the fact that the 35-kV overhead line is made on pores for 110-kV overhead lines. A high danger of surges is shown with such a configuration of the overhead line that includes a cable insert. A method for protecting against high-frequency surges is proposed using a frequency-dependent device operating on the use of an anomalous skin effect.

X–Ray therapy is an area of clinical radiology. It has been used with success for treating many non–oncological diseases, as well as malignant neoplasms. However, this type of radiotherapy lacks quality assurance protocols. Quality assurance in radiotherapy is defined as a complex program of compliance with physicotechnical, dosimetric, clinical, personnel, and organizational measures, taking account of the individual features of the patient’s body. This applies to all activities in radiotherapy institutions from the moment the patient is admitted to the moment of discharge and subsequent follow–up. From the point of view of physicotechnical support, quality control for X–ray therapy equipment involves a range of characteristics. The aim of the present work was to develop a quality assurance program for X–ray treatment equipment based on these characteristics. Working from the requirements for X–ray treatment equipment presented in various publications, the authors have compiled a list of daily and monthly checks.

The directions of experimental work being performed at NITI on severe accidents are reviewed. The results of this work are widely used in the validation of safety systems for nuclear power, improving the accuracy of the predictions of scenarios of severe accidents at nuclear power plants, and in the development and validation of the performance of new materials used in nuclear energy.

Well-connected quasicrystals Quasicrystals are unique materials combining long-range order with 'impossible' packing symmetries like fivefold rotation, forbidden in periodic structures. Until now, they have been found only in specific systems such as intermetallic compounds, block copolymers, or colloidal particles under the action of a laser standing-wave pattern. Now Talapin et al . have self-assembled colloidal nanoparticles into aperiodic quasicrystalline lattices by carefully tailoring their sizes and using a novel packing motif. They can obtain quasicrystals with nanoparticles made of several different combinations of materials, pointing to the fact that only sphere packing and simple inter-particle potentials are important for their formation, and not specific interactions between the components These quasicrystals can also connect to the ordinary (crystalline) world through a thin 'wetting' layer with structures resembling the classic Archimedean tiling pattern. Quasicrystals are ordered structures that lack any translational symmetry, challenging the classic conception of ordered solids as periodic structures. So far, they have been reported in certain systems and can, for example, form from intermetallic compounds and organic dendrimers. Here it is shown that colloidal inorganic nanoparticles from several materials can self-assemble into binary aperiodic superlattices with quasicrystalline order. The discovery of quasicrystals in 1984 changed our view of ordered solids as periodic structures 1 , 2 and introduced new long-range-ordered phases lacking any translational symmetry 3 , 4 , 5 . Quasicrystals permit symmetry operations forbidden in classical crystallography, for example five-, eight-, ten- and 12-fold rotations, yet have sharp diffraction peaks. Intermetallic compounds have been observed to form both metastable and energetically stabilized quasicrystals 1 , 3 , 5 ; quasicrystalline order has also been reported for the tantalum telluride phase with an approximate Ta 1.6 Te composition 6 . Later, quasicrystals were discovered in soft matter, namely supramolecular structures of organic dendrimers 7 and tri-block copolymers 8 , and micrometre-sized colloidal spheres have been arranged into quasicrystalline arrays by using intense laser beams that create quasi-periodic optical standing-wave patterns 9 . Here we show that colloidal inorganic nanoparticles can self-assemble into binary aperiodic superlattices. We observe formation of assemblies with dodecagonal quasicrystalline order in different binary nanoparticle systems: 13.4-nm Fe 2 O 3 and 5-nm Au nanocrystals, 12.6-nm Fe 3 O 4 and 4.7-nm Au nanocrystals, and 9-nm PbS and 3-nm Pd nanocrystals. Such compositional flexibility indicates that the formation of quasicrystalline nanoparticle assemblies does not require a unique combination of interparticle interactions, but is a general sphere-packing phenomenon governed by the entropy and simple interparticle potentials. We also find that dodecagonal quasicrystalline superlattices can form low-defect interfaces with ordinary crystalline binary superlattices, using fragments of (3 3 .4 2 ) Archimedean tiling as the ‘wetting layer’ between the periodic and aperiodic phases.