Displacement substoichiometric separations in radioanalytical chemistry

The principle of displacement substoichiometry and the possibilities of its practical use have been outlined. The substoichiometric separation of lead, arsenic, and zinc can be carried out by applying diethyldithiocarbamate complexes and solvent extraction.     

Analysis of repetitive mechanism signatures

A new signal decomposition for repetitive signatures is introduced. This is based on the concept of derived time series, produced by rearranging the original signal by using points one period apart. Time domain averaging is shown to be a special case of such rearrangement, and a second technique of variance analysis is presented. Applications to rotating machinery show that the decomposition can be very sensitive to various generating mechanisms, making them suitable for signature analysis of mechanical systems.     

Buchbesprechungen

Ohne Zusammenfassung     

Darstellung und Untersuchung von Aminoschwefeltrifluoriden sowie eines Hydrolyseprodukts, 1-(Fluorooxothio)-2,5-dihydropyrrol

Synthesis and Investigation of Aminosulphur Trifluorides and of a Hydrolysis Product 1-(Fluorooxothio)-2,5-dihydropyrrole The reaction of previously unknown (trimethylsilyl)amines with sulphur tetrafluoride gives some new aminosulphurtrifluorides. Experiments to cleaver 1-(Trifluorothio)-2,5-dihydropyrrole and 1-(trifluorothio)pyrrolidin into butadiene and ethylene respectively and NSF₃ by way of a chelotrope cycloelimination were unsuccessful. ¹H-NMR and ¹⁹F-NMR spectra revealed the nitrogen in the aminosulphur trifluorides must be regarded sp³ hybridized rather than sp².     

The kinetics of pyrolysis of barrelene[1]: A concerted process on the C8H8 energy surface

The static vessel pyrolysis of bicyclo[2.2.2]octa-2,5,7-triene (barrelene) has been studied between 483 and 523 K. The products were acetylene and benzene (in equal quantities) with no other detectable C₈H₈ isomer (down to less than 1% of total). The time dependence fitted first-order kinetics, and the data are consistent with a homogeneous unimolecular reaction close to, if not at, its high-pressure limit at 0.25 torr. The rate constant was fitted to the Arrhenius equation These Arrhenius parameters are shown to imply a concerted single-step process. Alternative mechanisms are discussed and a comparison is made with the retro-Diels—Alder reactions of other bicyclo[2.2.2]octa-olefin systems.     

Utilisation de l'antieatalyse dans la chimie analytique

Sans résumé     

Usage de l'Algèbre de Lie su (n) dans l'Etude des Systèmes Quantiques à n Etats. V. Application aux Systèmes composés

We adapt the use of the Lie algebra su (n) we proposed in former papers to a system made up of two subsystems (respectively, n_A and n_B states). We show how reduced density operators, correlation problems, and overall and reduced evolution equations, may be made precise with this formalism.     

Pomeron vertices in perturbative QCD in diffractive scattering

We analyze the momentum space triple pomeron vertex in perturbative QCD. In addition to the standard form of this vertex which is used in the context of total cross sections at high energies and in the QCD reggeon field theory, there exists an alternative form which has to be used in the study of high-mass diffraction. We review and analyze the relation between these two versions. We discuss some implications for the BK equation. In the second part of our paper we extend this analysis to the pomeron-odderon-odderon vertex.Received: 11 January 2005, Revised: 24 January 2005, Published online: 3 March 2005