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Here, we have thoroughly studied the effect of chemistry of graphene derivatives on the composition of N-species after N-doping with the help of core-level spectroscopy techniques. The modulation of the N-species by tailoring the functionalization and atomic structure of graphene derivatives prior to chemical N-doping is experimentally demonstrated for the first time. The large extent of non-terminated or phenol-functionalized graphene edges is found to facilitate the formation of pyridinic nitrogen with its relative content exceeding 72%. In turn, the predominant decoration by the pyrazolic moieties is shown for the perforated and carboxyl-derived graphene layers. The thermal annealing at moderate temperatures of ca.345 °C is shown to equally readjust the composition of N-species in graphene derivatives regardless of their chemistry, nanostructure, and the initial distribution of the N-species. Further examination of N K-edge X-ray absorption spectra (XAS) pointed out that the oxidation of the graphene layer governs the manifestation of the π∗ resonances and configuration of the σ∗ resonance. As a result, a set of facile methods to synthesize graphene derivatives with the desired type of the embedded nitrogen species for the optoelectronic and catalytic applications are proposed and crucial features of their identification using core-level spectroscopy techniques are emphasized.

A review of theoretical and experimental studies in the field of compression and heating of a plasma target in an external magnetic field, which has recently been called magneto-inertial fusion (MIF), has been carried out. MIF is a concept of magnetically driven inertial fusion that involves the magnetization of fuel, laser pre-heating, and magnetic implosion to create fusion conditions. An analysis of the current state of work on the implosion of magnetized targets and the effect of an external magnetic field on the main plasma parameters and system characteristics is presented. Questions regarding the numerical simulation of experiments on the magnetic-inertial confinement of plasma are touched upon. Particular attention is paid to two promising areas of MIF—with plasma jets and with a laser driver (laser beams).

Here, the synthesis of holey carbonylated (C-ny) graphene derivative and its application for gas sensing is demonstrated. The carbonylation of graphene oxide leads to the 3-fold increase in the concentration of carbonyl groups’ up to 9 at.% with a substantial elimination of other oxygen functionalities. Such a chemical modification is accompanied by the perforation of the graphene layer with the appearance of matrices of nanoscale holes, leading to corrugation of the layer and its sectioning into localized domains of the π-conjugated network. Combined with the predominant presence of carbonyls, granting the specificity in gas molecules adsorption, these features result in the enhanced gas sensing properties of C-ny graphene at room temperature with a selective response to NH3. Opposite chemiresistive response towards ammonia when compared to other analytes, such as ethanol, acetone, CO2, is demonstrated for the C-ny graphene layer both in humid and dry air background. Moreover, a selective discrimination of all of the studied analytes is further approached by employing a vector signal generated by C-ny multielectrode chip. Comparing the experimental results with the calculations performed in framework of density functional theory, we clarify the effect of partial charge transfer caused by water and ammonia adsorption on the chemiresistive response.

This paper considers the problem associated with the numerical simulation of the interaction between the cocurrent stream occurring near a monoblock moving in the gas medium and solid fuel combustion products flowing from a solid fuel rocket engine (SFRE). The peculiarity of the approach used is the description of gas-dynamic processes inside the combustion chamber, in the nozzle block, and the down jet based on a single calculation methodology. In the formulated numerical methodology, the calculation of gas-dynamic parameters is based on the solution of unsteady Navier–Stokes equations and the application of a hybrid computational grid. A hybrid block-structured computational grid makes it possible to calculate gas flow near bodies of complex geometric shapes. The simulation of the main phase of interaction, corresponding to the stationary mode of rocket flight in the Earth’s atmosphere, has been carried out. A conjugated simulation of the internal ballistics of SFRE and interaction of combustion products jets is conducted.

A mathematical model is formulated, and a numerical study of magneto-plasma compressor (MPC) discharges in gases for a wide range of changes in the main electrical parameters and the characteristics of the surrounding gas environment is carried out. The performed calculations showed, depending on the role of one or another heating mode (Ohmic, transient, and plasma dynamic), three different types of quasi-stationary spatial distributions of plasma parameters, which can be used to judge the features of the emerging structures and the dynamics of plasma propagation, and, therefore, to speak about the modes of discharge. The features of the radiation plasma dynamic structures and the change in the main parameters of the plasma of an MPC discharge in the transient regime are considered.

The main purpose of this article is to study the features of the structure and spectral brightness characteristics of pulsed emitting discharges of the magneto plasma compressor type in dense gases over a wide range of energy–power parameters. A numerical simulation of plasma dynamic magneto plasma compressor discharge in gases is carried out. Different quasi-stationary regimes have been studied and the main characteristics have been estimated.

Issues of numerical simulation of an experiment on compression and heating of a target in a magnetic field are discussed. It is found that the applied magnetic field predominantly increases the plasma lifetime and plasma jet characteristics (velocity, Mach number, density, etc.). An analysis of the effects of the application of an external magnetic field on the behavior of plasma-driven guns (plasma jets) and laser-driven systems (laser beams) is carried out. Thermodynamic questions in simulation of experiments on magnetic inertial synthesis are touched upon.

The mathematical model and the results of computer simulation of the processes of compression, heating, and energy release in a target under the hybrid influence of a system of pulsed plasma jets and intense laser radiation in magnetic inertial thermonuclear fusion are presented. The hybrid effects of intense energy flows on a single-layer cylindrical target are compared in the experimental and simulation conditions. The main radiation magnetic and gas dynamic parameters of the compressed and heated target plasma are evaluated as well.

The one-step method for graphene oxide (GO) simultaneous reduction and carboxylation via ultraviolet irradiation in the inert atmosphere has been reported. X-ray photoelectron spectroscopy (XPS) an...

An approximate mathematical model of the heat transfer processes in the laminar and turbulent boundary layers, which occur near the surface of an aircraft moving at the hypersonic speed in the Earth’s atmosphere, is derived. This mathematical model makes it possible to calculate the convective heat transfer on the surface of typical structural elements of modern perspective aircrafts. 2D versions of the calculations of convective heat fluxes for bodies of simple geometric shapes are performed.

A numerical model to calculate the heat transfer and resistance coefficients near the bodies of complex geometric shapes moving at high velocity is formulated. The processes of heat and mass transfer and flow around aircraft elements are considered. An algorithm for calculating heat fluxes and the heat transfer coefficient is proposed. The developed numerical technique can give an idea of the essential features of the flow, heat transfer at the end keels of the wings, and integral layouts of high-speed aircraft. An approximate mathematical model for calculating the heat transfer processes and resistance coefficients near the bodies of complex geometric shapes moving at high speed in the Earth’s atmosphere is formulated. The calculated results for convective heat transfer and friction coefficients for the X-33 and X-43 vehicles are obtained.

The deuterium - heliuum-3 (D-3He) fuel, so called low-radioactive cycle, is a compromise for the thermonuclear fusion, and it is considered to be much cleaner than the deuterium – tritium (D-T) reaction. Helium-3 mining issues are discussed. The paper also provides an estimate of the helium-3 isotope reserves on planet Earth.

The basic properties of the plasma of capillary discharges are discussed. A mathematical simulation of the interaction of pulsed plasma jets generated by a capillary discharge at atmospheric pressure is presented.

Methods for calculating the heat and neutron transport in structural elements of nuclear and fusion power devices are considered in the framework of statistical modeling and physical neutron kinetics based on the cross sections of interaction of neutrons with matter. Statistical modeling makes it possible to establish the nature of the neutron transport and energy in matter. In the extreme cases, within the framework of this approach, the diffusion and ballistic regimes are realized. In the calculation of heat transfer, the heat release associated with gamma quanta is also taken into account. The possibilities of these methods for estimation of the joint thermal effects of these factors are shown.

A mathematical model is presented that describes the effect of intense laser pulses of a rectangular shape on a two-layer cylindrical target. The fluxes of the intrinsic plasma radiation for seven spectral ranges are calculated as a function of the radial target coordinate. Spatial distributions of the total flux of the plasma radiation are presented.

A mathematical model for the compression process of a cylindrically symmetric thermonuclear target is presented. A numerical method of an increased accuracy order is considered, which is used to calculate the basic physical processes that occur in target plasma exposed to an external magnetic field.

Scientific reports 10(1), 6902 (2020). doi:10.1038/s41598-020-63935-3, In this paper we present a facile method for the synthesis of aminated graphene derivative through simultaneous reduction and amination of graphene oxide via two-step liquid phase treatment with hydrobromic acid and ammonia solution in mild conditions. The amination degree of the obtained aminated reduced graphene oxide is of about 4 at.%, whereas C/O ratio is up to 8.8 as determined by means of X-ray photoelectron spectroscopy. The chemical reactivity of the introduced amine groups is further verified by successful test covalent bonding of the obtained aminated graphene with 3-Chlorobenzoyl chloride. The morphological features and electronic properties, namely conductivity, valence band structure and work function are studied as well, illustrating the influence of amine groups on graphene structure and physical properties. Particularly, the increase of the electrical conductivity, reduction of the work function value and tendency to form wrinkled and corrugated graphene layers are observed in the aminated graphene derivative compared to the pristine reduced graphene oxide. As obtained aminated graphene could be used for photovoltaic, biosensing and catalysis application as well as a starting material for further chemical modifications., Published by Macmillan Publishers Limited, part of Springer Nature, [London]

The feasibility of a realization method for the three-dimensional surface of an aircraft moving with hypersonic velocity is numerically investigated. An approximate mathematical method, which has the same accuracy at much lower computational cost, is used for calculating convective heat transfer over complex geometric shape of a vehicle. Unstructured grids are applied for numerical tests. The hypersonic aircraft computational aerodynamic predictions and comparisons with experimental data are performed.

A combined scheme of hot plasma confinement is proposed, and laser and plasma-based methods for generating a megagauss field during the implosion of a magnetized target are described that allow the development of new high-density plasma sources for materials science experiments and advanced areas of power engineering. A procedure for numerical calculation of the physical processes involved in the target plasma in an external magnetic field is presented.

In this paper, basing on the thorough comparison of the size measurement results obtained by Laser Diffraction (LD) and microscopic methods, we demonstrate the LD method to provide reliable and accurate data on the lateral size of two-dimensional graphene oxide (GO) platelets. Taking cue from the experimental study and theoretical calculations of scattering patterns, model accounting for arising of diffraction pattern that can be correctly processed with common LD instrumentation is suggested.

In this work we present a facile method for the synthesis of the carboxylated graphene derivate. The resulting material contains up to 10.9 at.% of carboxyl groups and with negligible content of other oxygen-containing groups. Moreover, formation of large round-shaped nanoscale holes is observed due to the applied synthesis process. The synthesized graphene derivative is of high interest for the sensing applications due to combination of its conductive nature and chemical reactivity provided by the attached carboxyl groups.

In this paper, we for the first time demonstrate efficient nitrogen doping of graphene oxide (GO) with nitrogen concentration of up to 5 at.% via modified Hummers' method. Using X-ray photoelectron spectroscopy (XPS), X-ray absorbance spectroscopy (XAS) and Fourier transform infrared spectroscopy (FTIR) techniques, we have found out graphitic nitrogen to be the dominant type of the implemented nitrogen species. At the same time, the subsequent GO thermal reduction to graphene appears to result in a transformation of the graphitic nitrogen into pyridines and pyrroles. The mechanisms of the observed GO nitrogen doping and conversion of the nitrogen species are proposed, providing an opportunity to control the type and concentration of the implemented nitrogen within the approach. A two-time increase of the graphenes' conductivity is observed due to the performed nitrogen doping. Further comprehensive electrical studies combined with the transmission electron microscopy (TEM) and density functional theory (DFT) modeling have allowed us to estimate the conductivity mechanism and the impact of the implemented nitrogen. As a net result, a simple method to synthesize N-doped graphene with the desired type of the nitrogen species is developed, which leads to new perspective applications for graphene, i.e. supercapacitors, catalysis, and sensors.

A capillary discharge with an evaporating wall, namely system of pulsed plasma jets is considered. The structure of an underexpanded supersonic jet that expires from the plasma channel of the capillary discharge with an evaporating wall is investigated. The turbulent viscosity and thermal conductivity coefficients are calculated using the equations of the Coakley model. Numerical simulation is performed and spatial distributions of plasma pressure, and temperature for an array of three pulsed plasma jets at different moments of time are obtained.

Results of experiments on the formation of a compact toroidal magnetic configuration at the Compact Toroid Challenge setup are presented. The experiments were primarily aimed at studying particular formation stages. Two series of experiments, with and without an auxiliary capacitor bank, were conducted. The magnetic field was measured, its time evolution and spatial distribution over the chamber volume were determined, and its influence on the formation regimes was investigated.

The present work reports on compact toroid hydrogen plasma creation by means of a specially designed discharge system and results of magnetic fields introduction. Experiments in the compact toroid challenge (CTC) device at P.N. Lebedev Physical Institute (FIAN) have been conducted since 2005. The CTC device differs from the conventional theta-pinch formation in the use of an axial current for enhanced efficiency. We have used a novel technique to maximize the flux linked to the plasma. The purpose of this method is to increase the energy input into the plasma and the level of trapped magnetic flux using an additional toroidal magnetic field. A study of compact torus formation with axial and toroidal currents was done and a new method is proposed and implemented.

Magneto-inertial fusion (MIF) is an original technique of inertial thermonuclear fusion, where spherical and cylindrical gas or plasma configurations are compressed under the action of an external magnetic field. We present a brief review of recent data on laser- and plasma jet-driven MIF systems and possible ways they can be applied. This work also presents problems of and prospects for the application of such approaches.

The work is devoted to theoretical calculations of compression and energy release processes in the target, which is used in a magnetoinertial fusion (MIF) concept consisting of pulsed jets and intense laser radiation. A numerical technique, describing plasma-physical processes occurring in MIF system, is developed. The results of the calculation of the combined effects (pulsed jets and laser radiation acting on a cylindrical target in the end and perpendicular directions) of intense energy flows on a single-layer cylindrical target are presented. All the main plasma dynamic and radiative parameters of the compressed target plasma were found.

Aneutronic/low radioactive fuel is the way to clean and cheap energy of the future. An alternative scheme using compact toroids – field-reversed configuration or spheromak – may be applied for the reactor based on any magnetic confinement system. Even more, any fusion concept, including hybrid magneto-inertial fusion might use advantages of D–3He fuel. Advanced fuel, including helium-3 – based fusion plasma and alternative systems are reviewed. Different schemes of reactors, near-term technology and non-electric applications are discussed.