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This publication presents the clinical observation in a paediatric patient with haemangioma of the left stomach. The effectiveness of surgical treatment of this disease is also noted. We assess the challenges in diagnosis and the choice of treatment of this pathology in children and the effectiveness of surgical treatment disease.Primary cardiac tumours are rare; vascular tumours and haemangiomas are rarer. The clinical picture of heart haemangioma is non-specific and varies as per its location and size. Echocardiography is the main diagnostic method for this disease. However, in most cases of preoperative diagnostic examination, the pre-surgery diagnosis is not confirmed. The final diagnosis of capillary haemangioma is established following immunohistochemical staining of the surgical material. Thus far, owing to the rare occurrence, a generally accepted tactic for the treatment of such patients with vascular heart tumours has not been developed.This clinical case describes our experience of treating a rare pathology in children with unusual localisation as well as the rapid successful surgical removal of the tumour without complications and with a favourable post-surgery recovery period.Received 14 May 2020. Revised 15 June 2020. Accepted 26 June 2020.Funding: The study did not have sponsorship.Conflict of interest: Authors declare no conflict of interest.Author contributions Literature review: U.G. Kolbik, A.V. Gorustovich, Y.I. LinnikIllustrations: U.G. Kolbik, I.V. Sakharov, V.V. Drozdovskaya Drafting the article: U.G. Kolbik, A.V. Gorustovich, I.V. SakharovCritical revision of the article: I.V. Sakharov, M.M. Shved, Yu.I. LinnikSurgical treatment: A.V. Gorustovich, M.M. Shved, U.G. KolbikFinal approval of the version to be published: U.G. Kolbik, A.V. Gorustovich, Yu.I. Linnik, M.M. Shved, V.V. Drozdovskaya, I.V. Sakharov, K.V. Drozdovski

The study of the organic matter of Riphean-Vendian deposits, the features of its distribution are the subject of research by many authors. The problem of hydrocarbon of these deposits remains relevant. We have conducted studies of deep-seated rocks of the Lower Riphean of the kaltasinskaya suite of the Eastern-Askinskaya area, with an increased content of organic matter in individual intervals. In addition to standard research methods, the method of nuclear magnetic relaxation in a low magnetic field was used. This method allows determining the phase state of organic matter in the original rock without any impact and after isothermal heating of the rock at 350°C. The free induction signal and the type of solid-phase signal, which corresponds to the waveform for the asphaltene component of the oil, were analyzed. The predominant part of the liquid-phase signal - about 35%, is characterized by a transverse relaxation time of 540 ¼s, corresponding to the resinous component of organic matter. The quantitative ratio of asphaltenes before and after heat treatment was also analyzed. A significant decrease in its amount was recorded. During thermal exposure, more than 55% of light, more mobile hydrocarbon molecules are formed in the liquid-phase part of organic matter.

The work of many researchers is devoted to studying the problem of the features of the formation of the Bazhenov suite and organic matter. Various methods are used to study the type and state of organic matter, despite this, the problem associated with the phase state and type of organic matter in these deposits, the methods for studying those remains relevant. One of these methods is the NMR relaxation method in low fields. For the analysis of heavy oils, the method of simultaneous measurement of the free induction decay (FID) together with the decay of the echo signal in the Carr-Purcell-Meiboom-Gill (CPMG) pulse program was used. We studied the decay form of relaxation curves and their approximation by a mathematical model adequate for solid, liquid, and gaseous states of matter, which contains information on the geochemical and petrophysical properties of organic matter, as part of a single reservoir, including both the mineral part and the fluid part.

The paper describes the digital filter polychromator developed for Thomson scattering (TS) diagnostics. The device having ultra-low noise, high-speed detection system and up to 7 spectral channels is equipped with digitizer and single board computer for system control and data processing. The data acquisition system is capable to detect very short laser pulses of few ns width with low magnitude. This feature opens up new possibilities for the TS diagnostics design in modern fusion devices, which includes: operation with high background illumination, measurement of very low electron temperature and density at the plasma edge and scrape-off layer (SOL), separation of the TS signal and the stray light coming with a delay of several ns. The analysis of the TS signal waveform also gives a possibility to distinguish the TS and Mie scattering from the dust particles that is important for measurements in SOL. Owing to compactness and ultra-low energy consumption both optical and data processing units interfaced with optical Gigabit Ethernet were combined in a stand-alone device. Such all-in-one design with optical fiber input and optical digital output provides enhanced resistance to electromagnetic disturbances and simplify operation. A set of such polychromators can be mounted in a standard 19” rack and can be integrated with outer CODAC (Control, Data Access and Communication) system. Testing of the polychromators at the Globus-M2 tokamak has shown excellent performance of the developed serial devices.

We report on studies of electrically excited non-equilibrium 2D electrons and 2D plasmons in an AlGaN/GaN nanostructure. Optical access to 2D plasmons is provided by means of a metal grating fabricated at the nanostructure surface, while the properties of 2D electrons are examined in the samples without metal grating. The paper focuses on the creation of highly non-equilibrium conditions when the effective temperature of 2D electrons is much higher than the crystal lattice temperature. Such conditions are realized by applying short electrical pulses with a low repetition frequency. A method has been developed for independently determining the temperature of hot electrons and the temperature of the crystal lattice under an applied electric field. It has been shown that under highly non-equilibrium conditions the spectral density of terahertz electroluminescence of 2D plasmons can significantly exceed that of 2D electrons at a certain frequency.

Simulation analysis of III-N two-dimensional electron gas-based structures that could be used for stable monolithically integrated enhancement/depletion-mode circuits was carried out. Three different designs were proposed and analysed, including a novel p-GaN/AlN-GaN SPSL/GaN, which is expected to have lower ON-state resistance and higher transconductance than conventional normally-off GaN-based transistors.

The necessity for the development of a system of interrelated classifications of module surfaces was justified. Main distinctive features, based on which the general classification and the classification of module surfaces are developed, were determined. Examples of the development of the general classification and classification of one constructional types of working surface modules were provided.

We study the coherent dynamics of localized excitons in 100-periods of 2.5 nm thick (In,Ga)N/GaN quantum wells with 7.5% indium concentration, measured with spectroscopic resolution through two-pulse and three-pulse photon echoes at the temperature of 1.5 K. A long-lived coherent exciton dynamics is observed in the (In,Ga)N quantum wells: When the laser photon energy is tuned across the 43 meV-wide inhomogeneously broadened resonance line, the coherence time T2 varies between 45 and 255 ps, increasing with stronger exciton localization. The corresponding narrow homogeneous linewidths ranging from 5.2 to 29 {\mu}eV as well as the relatively weak exciton-phonon interaction (0.8 {\mu}eV/K) confirm a strong, quantum dot-like exciton localization in a static disordered potential inside the (In,Ga)N quantum well layers., Comment: 4 figs

In this paper, the high electron mobility transistor (HEMT) with p-GaN gate is developed. The article demonstrates development of normally-off p-GaN gate HEMT on heterostructure with AlN stop layer for p-GaN selective etching and formation of normally-on GaN HEMT on the same wafer. It is researched that the gate length and gate-to-drain length influence on transistor operation and its breakdown voltage. The ohmic contact resistance and leakage currents depend on etching RF mode. The developed normally-off transistor with gate length of 1 um and gate-to-drain length of 9.5um has a breakdown voltage of 500 V and drain current in open state of 350 mA/mm. It is established that 2 nm SiN under the gate metal influence on device work.

Terahertz radiation emission from an electrically excited AlGaN/GaN heterostructure with a surface metal grating was studied under conditions of two-dimensional (2D) electron heating by the lateral electric field. Intensive peaks related to nonequilibrium 2D plasmons were revealed in the terahertz emission spectra with up to 4 times selective amplification of the radiation emission in the vicinity of 2D plasmon resonance. This selective emission was shown to be frequency-controllable by the grating period. Exact spectral positions of the 2D plasmon resonances were preliminarily experimentally detected with the help of equilibrium transmission spectra measured at various temperatures. The resonance positions are in a satisfactory agreement with the results of theoretical simulation of the transmission spectra performed using a rigorous solution of Maxwell’s equations. The effective temperature of hot 2D electrons was determined by means of I– V characteristics and their analysis using the power balance equation. It was shown that for a given electric field, the effective temperature of nonequilibrium 2D plasmons is close to the hot 2D electron temperature. The work may have applications in GaN-based electrically pumped emitters of terahertz radiation.Terahertz radiation emission from an electrically excited AlGaN/GaN heterostructure with a surface metal grating was studied under conditions of two-dimensional (2D) electron heating by the lateral electric field. Intensive peaks related to nonequilibrium 2D plasmons were revealed in the terahertz emission spectra with up to 4 times selective amplification of the radiation emission in the vicinity of 2D plasmon resonance. This selective emission was shown to be frequency-controllable by the grating period. Exact spectral positions of the 2D plasmon resonances were preliminarily experimentally detected with the help of equilibrium transmission spectra measured at various temperatures. The resonance positions are in a satisfactory agreement with the results of theoretical simulation of the transmission spectra performed using a rigorous solution of Maxwell’s equations. The effective temperature of hot 2D electrons was determined by means of I– V characteristics and their analysis using the power balance ...

The conventional method for determining the effective ion charge Zeff is based on measurements of the bremsstrahlung intensity in the spectral regions free from line radiation. This paper describes the design of the Zeff diagnostics at the Globus-M tokamak as well as the results of the first measurements. With allowance for the emission intensity estimates, the geometry of the experiment was chosen; the filter monochromators for recording bremsstrahlung were designed and manufactured. Using the Thomson scattering data on T e (R) and n e (R) profiles, time dependences Zeff (t) were obtained in several shots of the Globus-M tokamak. The results of simulations Z eff performed using the ASTRA transport code are consistent with these measurements.

The results from calculations of the anisotropic fast particle distribution function in the Globus-M/M2 spherical tokamaks are presented. The calculations were performed using the NUEBAM code, the reasons for the anisotropy occurrence are discussed (injection geometry, low toroidal magnetic field and plasma current, presence of neutral particles). It is shown that the anisotropy decreases with increasing toroidal magnetic field and plasma current: the density of the slowed down fast ions with energies of E < 4 keV almost doubles and the averaged perpendicular velocity of fast ions increases.

Ion temperature is one of the most important parameters of high-temperature plasma. Information on the ion temperature spatial distribution is necessary for understanding and modelling of particle and energy transport processes, evaluating the effectiveness of plasma heating system operation. Active spectroscopy also known as CXRS (Charge eXchange Recombination Spectroscopy) is a powerful diagnostic tool for measurements of local values of ion temperature, and is widely used in experiments with magnetic confinement of high-temperature plasma. Active spectroscopy diagnostics on the Globus-M tokamak utilizes a tangentially injected heating beam of neutrals (hydrogen or deuterium atoms). The CXRS-system setup is described. The results of ion temperature measurements for the last Globus-M experimental campaign before the machine shutdown and further upgrading to higher values of magnetic field and plasma current are presented. Ion temperature significant rise in the experiments with moderate increasing of toroidal magnetic field and plasma current is detected and discussed.

Calculational analysis of different scattering mechanisms of two-dimensional electron gas in AlGaN/(AlN)/GaN and InAlN/(AlN)/GaN high-electron mobility transistors was carried out. It was found that the mobility of AlGaN-based structures at room temperature is mainly limited by inherent scattering mechanisms (namely, optical and acoustic phonon scattering), while the mobility in our InAlN-based structures is limited by the interface roughness scattering. The low-temperature mobility is found to be limited by the interface roughness scattering for both AlGaN- and InAlN-based structures.

A fast scanning probe which can penetrate inside the separatrix during discharge was developed for Globus-M2. The probe has been designed to move various sensor pins into the scrape-off layer. The driving force is provided by a crank-slider mechanism which is ensured maximum linear speed about 4 m/s. The paper presents probe head and drive system description.

We demonstrate a phosphor free, dichromatic GaN-based monolithic white LED with vertically stacked green and blue emitting multiple quantum wells. The optimal thickness of GaN barrier layer between green and blue quantum wells used is 8 nm. This device can be tuned over a wide range of correlated color temperature (CCT) to achieve warm white (CCT = 3600 K) to cool white (CCT = 13,000 K) emission by current modulation from 2.3 A/cm2 to 12.9 A/cm2. It is also demonstrated for the first time that a color rendering index (CRI) as high as 67 can be achieved with such a dichromatic source. The observed CCT and CRI tunability is associated with the spectral power evolution due to the pumping-induced carrier redistribution.

Dependence of electroluminescence spectrum shape of blue-cyan InGaN-based dichromatic double quantum well light emitting diodes on the thickness and doping level of the barrier between quantum wells was investigated numerically and experimentally.

To study microcirculation in patients with paranoid schizophrenia by laser Doppler flowmetry.Fifty-three patients at the age from 18 to 38 years with a diagnosis of 'paranoid schizophrenia' (F20.0) were examined in the acute psychotic state and after 3 weeks of therapy. The control group consisted of 20 healthy volunteers. To assess microcirculation, the noninvasive technique of laser Doppler flowmetry using a laser blood flow analyzer was used.Significant changes in the microcirculation persisting even over three weeks of therapy in patients were identified. The total microcirculation index was increased by 1.4 times which indicated the acceleration of blood flow. An increase in the average fluctuations of perfusion by 3.7 times and in the coefficient of variation by 1.9 times, which reflect the excessive strengthening of local mechanisms of regulation of microcirculation, were found. There were an increase in the myogenic tone and neurogenic tone of metarteriole and precapillary sphincters as well as bypass index.Цель исследования. Изучение состояния микроциркуляции у больных параноидной формой шизофрении методом лазерной допплеровской флоуметрии. Материал и методы. Обследованы 53 пациента в возрасте от 18 до 38 лет с диагнозом 'параноидная шизофрения' (по МКБ-10 F20.0) в остром психотическом состоянии и через 3 нед терапии. Контрольную группу составили 20 здоровых. Для оценки состояния микроциркуляции использовался неинвазивный метод лазерной допплеровской флоуметрии с помощью лазерного анализатора кровотока. Результаты и заключение. Выявлены изменения, которые сохранялись через 3 нед терапии: был повышен в 1,4 раза общий показатель микроциркуляции, что говорит об ускорении потока крови, и отмечены повышение среднего колебания перфузии в 3,7 раза и увеличение коэффициента вариации в 1,9 раза, которые отражают усиление локальных механизмов регуляции микрокровотока. Установлено также повышение миогенного тонуса и нейрогенного тонуса метартериол и прекапиллярных сфинктеров, а также увеличение значений показателя шунтирования.

Ca0.75 + 0.5xZr1.5Fe0.5(PO4)3 –x(SiO4)x (x = 0–0.5) solid solutions have been synthesized by a sol–gel process and characterized by X-ray diffraction, IR spectroscopy, and differential scanning calorimetry. As expected, the synthesized phosphatosilicates crystallize in a NaZr2(PO4)3-type structure (trigonal symmetry, sp. gr. R $$\bar {3}$$ c). The thermal expansion of the solid solutions has been studied by high-temperature X-ray diffraction in the temperature range from 25 to 800°C. Their thermal expansion parameters have been calculated and analyzed as functions of composition. High-density ceramics based on the Ca0.875Zr1.5Fe0.5(PO4)2.75(SiO4)0.25 phosphatosilicate have been produced by spark plasma sintering and their structure and properties have been studied in detail.

Heavily Si-doped Al x Ga1–x N mesastrip structures were grown by selective MOVPE technology. Al x Ga1–x N:Si mesastructures with x ~ 0.01–0.07 possess a smoother top and more even side surfaces as compared to those in analogous GaN:Si structures. During the growth of mesastructures with x ~ 0.03–0.07, a thin nanocrystalline AlN deposit appears on the Si3N4 mask. This deposit is not formed during the growth of structures with sufficiently low aluminum content.

InGaN-based monolithic multi-color light emitting diodes (LEDs) are studied both experimentally and theoretically with the focus on factors controlling their emission spectra and efficiency. A number of LEDs with different designs of spacers separating active regions providing blue and green light emission is examined. Unexpected behavior of the multi-color LED efficiency is explained in terms of a simple balance model, assuming some degradation of materials quality of the green active region grown on top of the blue one. Electrical properties of spacers separating different active regions in the multi-color LED structures are identified as the major factor controlling the contributions of these active regions to the total emission spectrum. Correlations between the type and level of the spacer doping and the emission spectrum are found by simulations. Alternative ways of the spectral control by using polarization doping in the graded-composition InGaN and AlGaN alloys used as the spacers are suggested. Color characteristics of blue/green dual-wavelength LEDs are also measured and discussed, regarding their possible applications.

The paper summarizes the experience of using traditional and modern methods of sintering WC–Co nanopowders obtained by plasma chemical synthesis. A comparative analysis of structure formation processes occurring at sintering WC–Co nanopowders in a quasi-steady and high-speed heating is carried out. It is shown that the basic regularities of structure evolution during sintering are rather general in nature and are similar both to conventional vacuum sintering and to high-energy compaction methods. It was established that, under high-speed heating conditions, a significant contribution to the acceleration of the sintering of nanopowder materials at low temperatures is made not only by a small grain size but also the process of grainboundary diffusion. It is shown that the samples of hard alloys sintered from tungsten carbide nanopowders produced by plasma chemical synthesis have significantly higher hardness and fracture toughness than those produced using conventional synthesis techniques and compacting. Using the technology of plasma chemical synthesis and spark plasma sintering, nanostructured WC and WC–Co samples with significantly better mechanical properties (hardness, fracture toughness) than those of conventional fine materials were obtained.

Research data for drag currents in the Globus-M spherical tokamak are presented. The currents are generated by injecting atomic beams of hydrogen and deuterium. Experiments were carried out in the hydrogen and deuterium plasma of the tokamak. It has a divertor configuration with a lower X-point, a displacement along the larger radius from–1.0 to–2.5 cm, and a toroidal field of 0.4 T at a plasma current of 0.17–0.23 MA. The beam is injected into the tokamak in the equatorial plane tangentially to the magnetic axis of the plasma filament with an impact diameter of 32 cm. To provide a 28-keV 0.5-MW atomic beam with geometrical sizes of 4 × 20 cm (at a power level of 1/e), an IPM-2 ion source is used. The generation of noninductive currents is detected from a rise in the loop current and a simultaneous dip of the loop voltage. The injection of the hydrogen and deuterium atomic beams into the deuterium plasma results in a noticeable and reproducible dip of the loop voltage (up to 0.5 V). Using the ASTRA transport code, a model is constructed that allows rapid calculation of noninductive currents. Calculations performed for a specific discharge confirm that the model adequately describes the effect of drag current generation.

The capacitance-voltage characteristics of (Al/Ti)/Al2O3/n-GaN metal—insulator-semiconductor (MIS) structures are measured and analyzed. n-Type GaN films are grown on sapphire (0001) substrates by the metal-organic chemical vapor deposition method. An aluminum-oxide layer with a thickness of 60 nm is deposited onto the surface of GaN by the method of atomic-layer deposition from the gas phase. Metallic contacts are deposited by the electron-beam evaporation of titanium and aluminum in vacuum. According to the measurement results, the breakdown-field strength of the oxide, its dielectric constant, and the integrated electron density of states at the oxide-semiconductor interface are 5 × 106 V/cm, 7.5, and 3 × 1012 cm−2, respectively.

We consider the motion of a system consisting of a rigid body and internal movable masses on a rough surface. The possibility of rotation of the system around its center of mass due to the motion of internal movable masses is investigated. To describe the friction between the body and the reference surface, a local Amontons-Coulomb law is selected. To determine the normal stress distribution in the contact area between the body and the surface, a linear dynamically consistent model is used. As examples we consider two configurations of internal masses: a hard horizontal disk and two material points, which move parallel to the longitudinal axis of the body symmetry in the opposite way. Motions of the system are analyzed for selected configurations.

The thermophysical parameters of a Cd0.2Hg0.8Te single crystal are investigated in the temperature range of 300–503 K. The investigated structure is shown to be stable upon heating to a temperature of 503 K. The decay of the Cd0.2Hg0.8Te phase composition under laser irradiation is established.

High-density samples of ultrafine-grained tungsten carbide with high hardness (up to 31–34 GPa) and increased fracture toughness (up to 5.2–6.4 MPa m1/2) are obtained using the technology of electropulse plasma sintering. The influence of the initial size of nanoparticles of α-WC prepared by plasmachemical synthesis on the density, structural parameters, and mechanical properties of tungsten carbide is investigated.

Spark Plasma Sintering studies of the high-speed consolidation of pure tungsten carbide WC nanopowders have been carried out. The influence of the initial size of the WC nanoparticles and modes of their receiption the density, structural parameters, and mechanical properties of tungsten carbide are studied. Samples of high-density nanostructured tungsten carbide with high hardness (up to 31–34 GPa) and an increased crack resistance (4.3–5.2 MPa m1/2) are obtained. It is found that the effect of accelerating tungsten carbide nanopowder sintering under conditions of high-speed heating is associated with the acceleration of diffusion along grain boundaries in the sintered material. It is shown that the nonmonotonic dependence of the optimal sintering temperature on the initial grain size is caused by a change in grain-boundary diffusion coefficient in conditions of abnormal grain growth. It is found that the size of abnormally large grains in spark plasma sintering depends on the volume fraction of particles of the nonstoichiometric phase.

Ultrafine-grained (UFG) tungsten carbide (WC) samples with high hardness (up to 34 GPa) and increased cracking resistance have been obtained by the method of spark plasma sintering (SPS). Initial powders have been prepared by two-stage plasmachemical synthesis. The influence of the initial size of WC nanoparticles on the density, structural parameters, and mechanical properties of UFG tungsten carbide obtained by SPS has been studied. It is established that the phenomenon of accelerated sintering of WC powder is related to enhanced grain-boundary diffusion.

We present the results of a comparative investigation of geodesic acoustic modes (GAMs) by the method of bicoherence analysis in tokamaks (Tuman-3M and Globus-M) with different aspect ratios. The obtained data provide indirect evidence of the mutual influence of GAMs and background turbulence of tokamak plasma. The cross-bicoherence spectra were calculated using the signals of Doppler reflectometers and temporal dependences of the velocity of plasma rotation in the electric field of GAMs. The level of bicoherence in both tokamaks increases before transition to the H-mode and then decays down to the noise level in the H-mode.

This paper provides an overview of Spark Plasma Sintering (SPS), which is an advanced technology for high-speed sintering of powder materials by applying mechanical pressure to the powder compact and heating it using a pulsed direct current. Some examples of the successful application of the SPS technology in producing materials with high strength characteristics are shown. By optimizing the SPS regimes, the hardness of pure WC ceramics Hv=30÷31 GPa (20% higher than that of conventional materials), hardness of pure Al2O3 ceramics Hv=23.5 GPa (50% higher than that of conventional materials) and limit strength of the heavy alloy W–Ni–Fe σT=2500 MPa (2 times higher than that of conventional materials) are achievable.

The paper presents results on optimizing the MOVPE technology of light-emitting diode (LED) structures in a Dragon-125 system to accelerate the technological cycle. Due to the high growth rate of GaN layers and optimization of the initial GaN growth phase, the total duration of the epitaxial process is reduced from 4 h 45 min to 2 h 44 min. The LED diode structures grown by this technique compare well in quality with LEDs grown by the standard method in the commercially available AIX2000HT system.

We demonstrate a resonant Bragg structure formed by quasi-two-dimensional excitons in periodic systems of InGaN quantum wells (QWs) separated by GaN barriers. When the Bragg resonance and exciton–polariton resonance are tuned to each other, the medium exhibits an exciton-mediated resonantly enhanced optical Bragg reflection. The enhancement factor appeared to be largest for the system of 60 QWs. Owing to a high binding energy and oscillator strength of the excitons in InGaN QWs, the resonant enhancement was achieved at room temperature. The samples were grown by the metal–organic vapor-phase epitaxy (MOVPE) on GaN-on-sapphire templates. The most important technological problem of the developed structures is inhomogeneous broadening of the excitonic states due to nonuniform chemical composition of the QWs driven by InN–GaN phase separation trend. We addressed this problem by variation of the vapor pressure, growth rate, growth interactions, and admixing of hydrogen during the MOVPE. The lowest width of 74 meV at room temperature and 41 meV at 77 K was achieved for the excitonic emission line from a single InGaN QW.

Optical lattices of excitons in periodic systems of InGaN quantum wells with GaN barriers are designed, implemented, and investigated. Due to the collective interaction of quasi-two-dimensional excitons with light and a fairly high binding energy of excitons in GaN, optical Bragg reflection at room temperature is significantly enhanced. To increase the resonance optical response of the system, new structures with two quantum wells in a periodic supercell are designed and implemented. Resonance reflection of 40% at room temperatures for structures with 60 periods is demonstrated.

Neutral beam injection into the Globus-M spherical tokamak at the early stage of discharge leads to the development of instabilities in a frequency range of 50–200 kHz, which have been identified as toroidal Alfven eigenmodes (TAEs) [1]. The influence of these modes on the confinement of fast particles has been studied with the aid of a neutral particle analyzer (NPA) and a neutron detector. The isotope effect was studied using hydrogen and deuterium both in the injected beam and in the target plasma. A correlation analysis of signals from magnetic probes showed that the observed modes in most cases contain a single harmonic with toroidal number n = 1. Upon the injection of deuterium into deuterium plasma, the development of TAEs led to a decrease in the neutron flux by 25%, whereas the fluxes of high-energy recharge atoms decreased by 75%. After the injection of hydrogen, a decrease in the flux measured by NPA did not exceed 25%.

The high-temperature consolidation of nanopowders of pure tungsten carbide by electropulse plasma sintering (spark plasma sintering) is investigated. The influence of the initial size of WC nanoparticles and their preparation modes on the density, structural parameters, and mechanical properties of tungsten carbide are investigated. Samples of high-density nanostructured tungsten carbide with high hardness (to 31 GPa) and crack resistance (5.2 MPa m1/2) are fabricated.

The first experimental results demonstrating that the carrier mobility in the AlGaN/GaN 2D channel of transistor structures (AlGaN/GaN-HEMT) is correlated with the manner in which the nanomaterial is organized and also with the operation reliability of transistor parameters are presented. It is shown that improving the nature of organization of the nanomaterials in AlGaN/GaN-HEMT structures, evaluated by the multifractal parameter characterizing the extent to which a nanomaterial is disordered (local symmetry breaking) is accompanied by a significant, several-fold increase in the electron mobility in the 2D channel and in the reliability of parameters of transistors fabricated from these structures.

Basal encephalocele is a rare disease that predominantly occurs in children. Its most common symptoms include nasal liquorrhea, difficulty in nasal breathing, and deformity of the naso-orbital region.The study group included 19 patients with basal encephalocele, aged 2 months to 18 years. Ten (59%) patients were operated on through a transnasal endoscopic approach; 3 (17.5%) patients were operated on through a transcranial approach; 4 (23.5%) patients were operated on using a combined approach: the patients underwent simultaneous elimination of a cranio-orbital region deformity using the basal transcranial approach as well as hernial sac resection and hernioplasty using the transnasal endoscopic approach. Two children had no surgery due to minimal symptoms and a lack of cerebrospinal fluid leak.Application of the algorithms for diagnosis and treatment of encephalocele, suggested by the authors, enabled making the timely diagnose, defining the optimal surgical tactics, and achieving good treatment results.A differentiated approach to the choice of a surgical technique for basal encephalocele, the use of auto-tissues for skull base reconstruction, intraoperative and postoperative lumbar drainage, and simultaneous elimination of deformity of the fronto-naso-orbital region enable avoiding complications and achieving good functional and aesthetic results.Базальные энцефалоцеле - редкая патология, выявляющаяся в большинстве случаев у детей. Среди наиболее частых ее симптомов можно выделить назальную ликворею, затруднение носового дыхания, деформацию назоорбитальной области. Материал и методы. Исследуемая группа - 19 пациентов с базальными энцефалоцеле в возрасте от 2 мес до 18 лет. Десять (59%) пациентов оперированы трансназальным эндоскопическим доступом, 3 (17,5%) - транскраниальным и 4 (23,5%) - комбинированным, одномоментно устранялась деформация краниоорбитальной области базальным транскраниальным доступом и проводилось трансназальное эндоскопическое устранение грыжевого мешка и пластика грыжевых ворот. Двое детей не оперированы ввиду минимальной выраженности симптомов и отсутствия ликвореи. Результаты. Применение предложенных авторами алгоритмов диагностики и лечения энцефалоцеле позволило своевременно поставить диагноз, определить оптимальную хирургическую тактику и достигнуть хороших результатов лечения. Заключение. Дифференцированный подход к выбору метода хирургии при базальных энцефалоцеле, использование аутотканей для пластики основания черепа, люмбальное дренирование интраоперационно и после операции, одновременное устранение деформации фронтоназоорбитальной области позволяют избежать осложнений, добиться хороших функциональных и эстетических результатов.

International audience; We present a study of blue III-nitride light-emitting diodes (LEDs) with multiple quantum well (MQW) and quantum dot (QD) active regions (ARs), comparing experimental and theoretical results. The LED samples were grown by metalorganic vapor phase epitaxy, utilizing growth interruption in the hydrogen/nitrogen atmosphere and variable reactor pressure to control the AR microstructure. Realistic configuration of the QD AR implied in simulations was directly extracted from HRTEM characterization of the grown QD-based structures. Multi-scale 2D simulations of the carrier transport inside the multiple QD AR have revealed a non-trivial pathway for carrier injection into the dots. Electrons and holes are found to penetrate deep into the multi-layer AR through the gaps between individual QDs and get into the dots via their side edges rather than via top and bottom interfaces. This enables a more homogeneous carrier distribution among the dots situated in different layers than among the laterally uniform quantum well (QWs) in the MQW AR. As a result, a lower turn-on voltage is predicted for QD-based LEDs, as compared to MQW ones. Simulations did not show any remarkable difference in the efficiencies of the MQW and QD-based LEDs, if the same recombination coefficients are utilized, i.e. a similar crystal quality of both types of LED structures is assumed. Measurements of the current–voltage characteristics of LEDs with both kinds of the AR have shown their close similarity, in contrast to theoretical predictions. This implies the conventional assumption of laterally uniform QWs not to be likely an adequate approximation for the carrier transport in MQW LED structures. Optical characterization of MQW and QD-based LEDs has demonstrated that the later ones exhibit a higher efficiency, which could be attributed to better crystal quality of the grown QD-based structures. The difference in the crystal quality explains the recently observed correlation between the growth pressure of LED structures and their efficiency and should be taken into account while further comparing performances of MQW and QD-based LEDs. In contrast to experimental results, our simulations did not reveal any advantages of using QD-based ARs over the MQW ones, if the same recombination constants are assumed for both cases. This fact demonstrates importance of accounting for growth-dependent factors, like crystal quality, which may limit the device performance. Nevertheless, a more uniform carrier injection into multi-layer QD ARs predicted by modeling may serve as the basis for further improvement of LED efficiency by lowering carrier density in individual QDs and, hence, suppressing the Auger recombination losses.

Praseodymium and neodymium phosphates Ca9Ln(PO4)7 of the whitlockite structure were synthesized in the form of powders via solid-phase reactions at high temperatures and in the form of ceramics using the two-step pressing + sintering process and one-step high-rate spark plasma sputtering (SPS) procedure. According to X-ray diffraction data, the phosphates were structural analogs of calcium phosphate, namely, of its low-temperature modification β-Ca3(PO4)2, space group R3c. The particle size in the powders was 80–110 nm. The relative densities of the ceramics reached 99% when using SPS. The optimum conditions were found for obtaining high-density ceramics containing Pr and Nd. Their mechanical characteristics (microhardness, cracking resistance) were determined, and the microstructure was characterized.

Final stage of the degradation of the external quantum efficiency of AlGaN/GaN UV light-emitting diodes (LEDs), grown by chloride-hydride vapor-phase epitaxy, and high-power InGaN/GaN blue LEDs, produced by metal-organic vapor-phase epitaxy, has been comparatively studied. It is shown that one of these processes leading to a decrease in the quantum efficiency for both types of LEDs is the local defect formation involving the Gold-Weisberg mechanism in a system of extended defects. To prolong the service life of AlGaN/GaN UV LEDs to more than 2000 h, it is necessary to improve the nanostructural arrangement of the material of light-emitting structures and determine the contribution from the AlGaN composition disorder to the degradation of the external quantum efficiency.

Conversion of the near-surface regions of InGaN into GaN during growth interruption has been studied. It has been established that the process exhibits saturation in time, develops at a depth below 2 nm, and proceeds in a similar way in the presence and absence of hydrogen, although hydrogen supply significantly accelerates the conversion process. InGaN/GaN heterostructures obtained with interruption of growth exhibit an additional photoluminescence line with a longer wavelength as compared to that for an otherwise analogous continuous InGaN layer. It is established that growth interruption in a hydrogen-free atmosphere is more favorable for obtaining light-emitting structures for the green spectral range.

The structure and mechanical properties of nano- and ultradispersed mechanically activated heavy W-Ni-Fe and W-Ni-Fe-Co tungsten alloys (VNZh and VNZhK alloys, respectively) are studied. Mechanically activated nano- and ultradispersed charge powders are sintered by free sintering (thermally activated) and spark plasma sintering. The dependence of the density of the alloys made of the mechanically activated powders on the sintering temperature is found to have a nonmonotonic character with a maximum corresponding to the optimum sintering temperature. It is shown that an increase in the mechanical activation time and the acceleration of the milling bodies during mechanical activation lead to a decrease in the alloy particle size and the formation of nonequilibrium solid solutions and are accompanied by a decrease in the optimum sintering temperature of heavy tungsten alloys. Ultrahigh-strength tungsten alloys the mechanical properties of which are substantially higher than those of standard coarse-grained analogs are fabricated due to the optimization of the conditions of ball milling and high-rate spark plasma sintering of W-Ni-Fe powders.