Time filter

Source Type

Moscow, Russia

The Peoples' Friendship University of Russia is an educational and research institution located in southern Moscow. It is ranked by the Ministry of Education of Russia as the country's third-best university after Moscow State University and Saint Petersburg State University Wikipedia.

Ivashchuk V.D.,Peoples Friendship University of Russia
International Journal of Geometric Methods in Modern Physics | Year: 2010

A (n + 1)-dimensional Einstein-Gauss-Bonnet (EGB) model is considered. For diagonal cosmological-type metrics, the equations of motion are reduced to a set of Lagrange equations. The effective Lagrangian contains two "minisuperspace" metrics on ℝn. The first one is the well-known 2-metric of pseudo-Euclidean signature and the second one is the Finslerian 4-metric that is proportional to n-dimensional Berwald-Moor 4-metric. When a "synchronous-like" time gauge is considered, the equations of motion are reduced to an autonomous system of first-order differential equations. For the case of the "pure" GaussBonnet model, two exact solutions with power-law and exponential dependence of scale factors (with respect to "synchronous-like" variable) are obtained. (In the cosmological case, the power-law solution was considered earlier in papers of N. Deruelle, A. Toporensky, P. Tretyakov and S. Pavluchenko.) A generalization of the effective Lagrangian to the Lowelock case is conjectured. This hypothesis implies existence of exact solutions with power-law and exponential dependence of scale factors for the "pure" Lowelock model of mth order. © 2010 World Scientific Publishing Company. Source

Ivashchuk V.D.,Peoples Friendship University of Russia
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010

A family of spherically symmetric solutions with horizon in the model with m-component anisotropic fluid is presented. The metrics are defined on a manifold that contains a product of n-1 Ricci-flat "internal" spaces. The equation of state for any s-th component is defined by a vector Us belonging to Rn+1. The solutions are governed by moduli functions Hs obeying non-linear differential equations with certain boundary conditions imposed. A simulation of black brane solutions in the model with antisymmetric forms is considered. An example of solution imitating M2-M5 configuration (in D=11 supergravity) corresponding to Lie algebra A2 is presented. © 2010 Elsevier B.V. Source

Chernetsova E.S.,Peoples Friendship University of Russia | Morlock G.E.,University of Hohenheim
Mass Spectrometry Reviews | Year: 2011

Direct analysis in real time (DART), a relatively new ionization source for mass spectrometry, ionizes small-molecule components from different kinds of samples without any sample preparation and chromatographic separation. The current paper reviews the published data available on the determination of drugs and drug-like compounds in different matrices with DART-MS, including identification and quantitation issues. Parameters that affect ionization efficiency and mass spectra composition are also discussed. © 2011 Wiley Periodicals, Inc. Source

Sheka E.F.,Peoples Friendship University of Russia
International Journal of Quantum Chemistry | Year: 2012

The correlation of odd electrons in graphene turns out to be significant so that the species should be attributed to correlated ones. This finding profoundly influences the computational strategy addressing it to multireference computational schemes. Owing to serious problems related to the schemes realization, a compromise can be suggested using single-determinant approaches based on either Hartree-Fock or density-functional theory in the form of unrestricted open-shell presentation. Both computational schemes enable to fix the electron correlation, whereas only the Hartree-Fock theory suggests a set of quantities to be calculated that can quantitatively characterize the electron correlation and be used for a quantitative description of such graphene properties as magnetism, chemical reactivity, and mechanical response. The article presents concepts and algorithms of the unrestricted Hartree-Fock theory applied for the consideration of magnetic properties of nanographenes, their chemical modification by the example of stepwise hydrogenation, as well as a possible governing the electron correlation by the carbon skeleton deformation. © 2012 Wiley Periodicals, Inc. Source

Popov I.A.,Utah State University | Bozhenko K.V.,Peoples Friendship University of Russia | Boldyrev A.I.,Utah State University
Nano Research | Year: 2012

We analyze the chemical bonding in graphene using a fragmental approach, the adaptive natural density partitioning method, electron sharing indices, and nucleus-independent chemical shift indices. We prove that graphene is aromatic, but its aromaticity is different from the aromaticity in benzene, coronene, or circumcoronene. Aromaticity in graphene is local with two π-electrons delocalized over every hexagon ring. We believe that the chemical bonding picture developed for graphene will be helpful for understanding chemical bonding in defects such as point defects, single-, double-, and multiple vacancies, carbon adatoms, foreign adatoms, substitutional impurities, and new materials that are derivatives of graphene. © 2011 Tsinghua University Press and Springer-Verlag Berlin Heidelberg. Source

Discover hidden collaborations