Features of the Zeeman splitting of levels of the 1snp configurations of helium

The Zeeman splitting of the fine-structure levels of the 1s2p and 1s4p configurations of neutral helium in a magnetic field is calculated. The strengths of fields of intersection of magnetic sublevels are determined, and the field regions are found in which a constant energy gap between some sublevels is observed. The results are compared with the experimental data available in the literature.     

DFT computational schemes for 15N NMR chemical shifts of the condensed nitrogen-containing heterocycles

A systematic density functional theory (DFT) study of the accuracy factors (functionals, basis sets, and solvent effects) for the computation of ¹⁵N NMR chemical shifts has been performed in the series of condensed nitrogen-containing heterocycles. The behavior of the most representative functionals was examined based on the benchmark calculations of ¹⁵N NMR chemical shifts in the reference set of compounds. It was found that the best agreement with experiment was achieved with OLYP functional in combination with aug-pcS-3(N)//pc-2 locally dense basis set scheme providing mean absolute error of 5.2 ppm in the range of about 300 ppm. Taking into account solvent effects was performed within a general Tomasi's polarizable continuum model scheme. It was also found that computationally demanding supermolecular solvation model computations essentially improved some “difficult” cases, as was illustrated with phenanthroline dissolved in methanol. Based on the performed calculations, some 200 unknown ¹⁵N NMR chemical shifts were predicted with a high level of confidence for about 50 real-life condensed nitrogen-containing heterocycles, which could serve as a practical guide in structural elucidation of this class of compounds.     

A new way to compute the Lyapunov characteristic exponents for non-smooth and discontinues dynamical systems

Nonlinear Dynamics - One of the most important problems of nonlinear dynamics is related to the development of methods concerning the identification of the dynamical modes of the corresponding...     

Bernoulli-Euler Beam Under Action of a Moving Thermal Source: Characteristics of the Dynamic Behavior

Doklady Physics - The problem of a heating source acting on a certain part of a beam surface and moving along it with given speed $${v}$$ is solved. It is shown that the most significant role in...     

Lattice of Definability in the Order of Rational Numbers

Mathematical Notes - A lattice of definability subspaces in the order of rational numbers is described. It is proved that this lattice consists of five subspaces defined in the paper that are...     

Chemical Preparation of the Surface of a Porous Nickel Matrix for Conducting the Synthesis of TiC Nanolayer

Russian Journal of General Chemistry - The features of the porous nickel surface preparation for conducting the chemical processes of nanostructuring the dispersed phase TiC on the nickel surface...     

Synchrotron,X-Ray,and Electron Microscopic Studies of Catalyst Systems Based on Multiwalled Carbon Nanotubes Modified by Copper Nanoparticles

Physics of the Solid State - The results of the studies of a composite based on multiwalled carbon nanotubes (MWCNTs), onto the outer surface of which nanosized copper particles are deposited by...     

The Properties of xBiFeO3–(1 – x)SrTiO3 (x = 0.2–1.0; Δx = 0.1) Solid Solutions: Mössbauer Studies

Physics of the Solid State - The magnetic structure and phase transition in xBiFeO3–(1 – x)SrTiO3 solid solutions, where x is from 0.2 to 1.0 with a step of 0.1, are studied...     

An integer programming formulation of the key management problem in wireless sensor networks

With the advent of modern communications systems, much attention has been put on developing methods for securely transferring information between constitue     

Optical Diagnostics of Supercritical CO2 and CO2-Ethanol Mixture in the Widom Delta

The supercritical CO₂ (scCO₂) is widely used as solvent and transport media in different technologies. The technological aspects of scCO₂ fluid applications strongly depend on spatial–temporal fluctuations of its thermodynamic parameters. The region of these parameters’ maximal fluctuations on the p-T (pressure-temperature) diagram is called Widom delta. It has significant practical and fundamental interest. We offer an approach that combines optical measurements and molecular dynamics simulation in a wide range of pressures and temperatures. We studied the microstructure of supercritical CO₂ fluid and its binary mixture with ethanol in a wide range of temperatures and pressures using molecular dynamics (MD) simulation. MD is used to retrieve a set of optical characteristics such as Raman spectra, refractive indexes and molecular refraction and was verified by appropriate experimental measurements. We demonstrated that in the Widom delta the monotonic dependence of the optical properties on the CO₂ density is violated. It is caused by the rapid increase of density fluctuations and medium-sized (20–30 molecules) cluster formation. We identified the correlation between cluster parameters and optical properties of the media; in particular, it is established that the clusters in the Widom delta acts as a seed for clustering in molecular jets. MD demonstrates that the cluster formation is stronger in the supercritical CO₂-ethanol mixture, where the extended binary clusters are formed; that is, the nonlinear refractive index significantly increased. The influence of the supercritical state in the cell on the formation of supersonic cluster jets is studied using the Mie scattering technique.