A unification of the interactions and the diffractive processes

The transition of a number of hadronic process characteristics to a certain universal regime is interpreted as an indication to the early origination of the unification regime of the interactions

The mixing height in urban areas: comparative study for Copenhagen

International audienceThe urban boundary layer (UBL), in comparison with "rural" homogeneous atmospheric boundary layers, is characterised by greatly enhanced mixing, resulting from both the large surface roughness and increased surface heating, and by horizontal heterogeneity of the mixing height (MH) and other meteorological fields due to variations in surface roughness and heating from rural to central city areas. So, the UBL is considered as a specific case of the atmospheric boundary layer (ABL) over a non-homogeneous terrain. Therefore it is important to study how much the MH characteristics differ in urban and rural, marine or other more homogeneous areas. Most of the parameterisations of MH were developed for the conditions of a homogeneous terrain, so their applicability for urban conditions should be verified. Just a few authors suggested specific methods for MH determination in urban areas. In this paper the MH over urban, semi-urban, rural and marine areas of the Copenhagen metropolitan area is considered. Proceeding from the data from the Jægersborg radiosounding station measurement and analysis of different methods of the MH estimation, the peculiarities of the UBL and intercomparison of different MH estimation methods for urban and rural conditions are discussed. It is shown that the urban MH is considerably bigger for stably stratified (nocturnal) boundary layer cases in comparison with the "non-urban" MH. Daytime (usually the convective boundary layer) MH does not differ significatly in urban and "non-urban" sectors

Theoretical investigation of TbNi_{5-x}Cu_x optical properties

In this paper we present theoretical investigation of optical conductivity for intermetallic TbNi_{5-x}Cu_x series. In the frame of LSDA+U calculations electronic structure for x=0,1,2 and on top of that optical conductivities were calculated. Disorder effects of Ni for Cu substitution on a level of LSDA+U densities of states (DOS) were taken into account via averaging over all possible Cu ion positions for given doping level x. Gradual suppression and loosing of structure of optical conductivity at 2 eV together with simultaneous intensity growth at 4 eV correspond to increase of Cu and decrease of Ni content. As reported before [Knyazev et al., Optics and Spectroscopy 104, 360 (2008)] plasma frequency has non monotonic doping behaviour with maximum at x=1. This behaviour is explained as competition between lowering of total density of states on the Fermi level N(E_F) and growing of number of carriers. Our theoretical results agree well with variety of recent experiments.Comment: 4 pages, 3 figure

Electronic structure, magnetic and optical properties of intermetallic compounds R2Fe17 (R=Pr,Gd)

In this paper we report comprehensive experimental and theoretical investigation of magnetic and electronic properties of the intermetallic compounds Pr2Fe17 and Gd2Fe17. For the first time electronic structure of these two systems was probed by optical measurements in the spectral range of 0.22-15 micrometers. On top of that charge carriers parameters (plasma frequency and relaxation frequency) and optical conductivity s(w) were determined. Self-consistent spin-resolved bandstructure calculations within the conventional LSDA+U method were performed. Theoretical interpetation of the experimental s(w) dispersions indicates transitions between 3d and 4p states of Fe ions to be the biggest ones. Qualitatively the line shape of the theoretical optical conductivity coincides well with our experimental data. Calculated by LSDA+U method magnetic moments per formula unit are found to be in good agreement with observed experimental values of saturation magnetization.Comment: 16 pages, 5 figures, 1 tabl

Ab initio exchange interactions and magnetic properties of Gd2Fe17 iron sublattice: rhombohedral vs. hexagonal phases

In the framework of the LSDA+U method electronic structure and magnetic properties of the intermetallic compound Gd2Fe17 for both rhombohedral and hexagonal phases have been calculated. On top of that, ab initio exchange interaction parameters within the Fe sublattice for all present nearest and some next nearest Fe ions have been obtained. It was found that for the first coordination sphere direct exchange interaction is ferromagnetic. For the second coordination sphere indirect exchange interaction is observed to be weaker and of antiferromagnetic type. Employing the theoretical values of exchange parameters Curie temperatures Tc of both hexagonal and rhombohedral phases of Gd2Fe17 within Weiss mean-field theory were estimated. Obtained values of Tc and its increase going from the hexagonal to rhombohedral crystal structure of Gd2Fe17 agree well with experiment. Also for both structures LSDA+U computed values of total magnetic moment coincide with experimental ones.Comment: 20 pages, 2 figures; V2 as published in PR

Specific features of the electronic structure and spectral properties of NdNi5 - xCux compounds

The spectral properties of the intermetallic compounds NdNi5 - xCux (x = 0, 1, 2) have been studied using optical ellipsometry in the wavelength range 0.22-16 μm. It has been established that substitution of copper atoms for nickel leads to noticeable changes in the optical absorption spectra, plasma frequencies, and relaxation frequencies of conduction electrons. Spin-polarized calculations of the electronic structure of these compounds have been performed in the local spin density approximation allowing for strong electron correlations (LSDA + U method) in the 4f shell of the rare-earth ion. The calculated electron densities of states have been used to interpret the experimental dispersion curves of optical conductivity in the interband light absorption region. © 2013 Pleiades Publishing, Ltd

Optical spectroscopy and electronic structure of compounds HoNi 5-x Alx (x = 0, 1, 2)

The optical properties of the compounds HoNi5 - x Al x (x = 0, 1, 2) have been investigated using the ellipsometric method in the wavelength range from 0.22 to 16 μm. The electronic structure of these intermetallic compounds has been calculated in the local electron-spin density approximation with the correction for strong electronic interactions in the 4f shell of the holmium ions. The experimental dispersion dependences of optical conductivity in the region of interband light absorption have been interpreted based on the results of the calculation of the electron density of states. The plasma and relaxation frequencies of electrons have been determined. © 2013 Pleiades Publishing, Ltd

NEW “GREEN” METHOD OF BROMINATION OF (–)-NOPINONE AND (+)-CIS-VERBANONE

This work was supported by the Integrated Program of Ural Branch of RAS (project № 18-3-3-17)