Influence of phase noise on OFDM data transmission systems

We discuss the influence of the phase noise on OFDM data transmission systems. It is shown that intercarrier interference appearing due to the influence of the phase fluctuations on the OFDM communication system can be represented as two components, one of which has a uniform distribution across all the subcarriers, while the other has a nonuniform frequency-selective distribution determined by the transmission function of the communication channel. Therefore, the total distribution of intercarrier interference is frequency-selective with a higher power concentrated at stronger subcarriers. It is shown that the phase-noise influence on the OFDM communication system in frequency-selective communication channels is relatively weaker than that in frequency-flat channels without time dispersion.     

Terahertz heterodyne receivers based on superconductive hot-electron bolometer mixers

We consider recent results in development of hot-electron bolometer mixers. Special attention is paid to optimization of the contacts between the antenna and the active area of a superconducting film. An important result in the study of the parasitic effect of direct detection is obtained during the measurement of the noise temperatures by the hot/cold load method. The latest results of studies of the waveguide hot-electron bolometer mixers and their successful practical applications are considered. Progress in development of high-frequency (over 1.3 THz) heterodyne receivers for several important international projects is discussed and new submillimeter radio astronomy projects ESPRIT and SAFIR are described.     

Oxidation of Copper with Dicarbonylcyclopentadienyliron Chloride in Polar Solvents

Dicarbonylcyclopentadienyliron chloride oxidizes copper in dimethylformamide and dimethyl sulfoxide to give copper(II) chloride and dicarbonylcyclopentadienyliron dimer. The apparent kinetic characteristics of the process and the thermodynamic parameters of adsorption of reactants on the metal surface were determined. The reaction scheme was proposed.     

Oxidation of Palladium with Allyl Bromide and Iodine in Dimethylformamide

The kinetic features of palladium oxidation with allyl bromide and iodine in dimethylformamide were determined. The apparent equilibrium constants, enthalpies, and entropies of reactant adsorption on the palladium surface were calculated.     

Photodecomposition of substituted <Emphasis Type="Italic">o</Emphasis>-benzoquinones in solutions of saturated hydrocarbons: II. Transformation products

The products of photolytic decomposition of a series of o-benzoquinones in paraffin solutions under the action of the radiation with λ 405 nm were identified. The influence of the quinone structure on the reaction pathway and the composition of the final products was elucidated.     

Photodecomposition of substituted <Emphasis Type="Italic">o</Emphasis>-benzoquinones in saturated hydrocarbons: I. Kinetic relations

Kinetic relations holding in photodecomposition of substituted o-benzoquinones were determined, and primary photodecomposition products were identified. Photochemical transformations of o-benzoquinones in saturated hydrocarbons were presumed to follow two pathways: decarbonylation and reduction. The first of these is favored by the presence of electron-donor substituents in the quinoid ring.     

Oxidation of Magnesium,Indium, and Thallium with Molybdenum and Cobalt Binuclear Carbonyl Complexes in Polar Solvents

Oxidation of magnesium and thallium with bis(η5-cyclopentadienyltricarbonylmolybdenum) in dimethyl sulfoxide and of indium with octacarbonyldicobalt in tetrahydrofuran was studied. The formal-kinetics relationships of the processes were revealed, and the intermediate and final products were identified. The apparent equilibrium constants, enthalpies and entropies of adsorption of reactants on the metal surface, and rate constants and activation energies of the reactions were determined. The reaction scheme was suggested.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 529Original Russian Text Copyright © 2005 by Maslennikov, Malysheva, Spirina, Artemov.     

Physicochemical behavior of uranium and technetium in some new stages of the nuclear fuel cycle

Recently published results of the cooperative studies executed by the Institute of Physical Chemistry and Electrochemistry of Russian Academy of Sciences (IPCE RAS), Research Center Vallée du Rhone (CEA, France), Institute of Nuclear Physics Orsay and University Bordeaux I [Centre Nationale de Recherches Scientifiques (CNRS), France] are reviewed. The review includes data obtained for the first time on the electrochemical properties and anodic dissolution of uranium monocarbide considered among possible bases of the fuel for the reactors of the IVth generation. The results of the investigations in the field of the synthesis of tetraalkyl ammonium pertechnetates, their physicochemical properties and thermal decomposition with formation of Tc metal and Tc monocarbide are summarized. The electrochemical reactions with participation of Tc ions in various oxidation states and their application in the nuclear fuel cycle are described. The behavior of technetium in natural waters near the locations of the radwastes long-term storage and in the areas surrounding nuclear power plants in RF and France was studied.