No abstract available

[en] Autoradiography allows a dynamic, and in some cases a quantitative study of cell systems. It is now considered as a most efficient method when approaching conduction and morphogenetic problems in plant biology. The following technical aspects are described: tracer incorporation; autoradiographs; histoautoradiographs

[en] Apparently anomalous behaviour arises if a radiolabelled drug and a nonradioactive drug compete for binding to a membrane-bound receptor when (a) there is severe depletion of the radiolabelled drug and (b) the non-radioactive drug binds to a heterogeneous population of binding sites. In extreme cases, binding of the non-radioactive drug to the sites of high affinity can be obscured completely. This phenomenon is illustrated by the binding of carbachol to muscarinic receptors, estimated by inhibition of a radiolabelled antagonist. (orig.)

[en] Various isotope exchange reactions for the introduction of tritium into a range of organic compounds have been investigated. The influence of the catalyst, solvent and reaction conditions on the yield and specific activities of a number of steroids, phytohormones and sugars are reported. Heterogeneous hydrogen isotope exchange with gaseous tritium has also been used to label a number of nonpolar compounds. Similarly the potential of solid state hydrogen isotope exchange has been explored. The reaction mechanism is discussed as well as the influence of the reaction conditions on the specific activity and the label distribution. (author)

[en] The method of catalytic isotope exchange of tritium in gas solid phase was studied in this paper in order to label high molecular weight alcohols. The e specific activity of the product was 1-10 Ci/mmol and the radiochemical purity more than 98%. The ground glass used as reaction media and Pd/C as catalyst, permitted to obtain a high values of reaction yields and incorporated activity

[en] The programme EXOTIC (Extraction Of Tritium In Ceramics) progressed. In 1989 the EXOTIC-5 irradiation experiment was performed with materials from NRL, SCK/CEN, KfK-Karlsruhe, CEA-Saclay, ENEA and ECN. In this report results on tritium release ar given. (author). 5 refs.; 11 figs.; 9 tabs

[en] A comprehensive account of the title topic, divided into chapters as follows: Introduction (history, definition and nomenclature), Synthesis (hydrogen isotope compounds, carbon isotope compounds, compounds of isotopes of halogens, isotopes of other light elements (oxygen, nitrogen, phosphorus, sulfur), compounds of isotopes of heavier elements, particularly metals), Analysis (purity, chromatography, NMR spectroscopy, mass spectrometry, vibrational spectroscopy), and Applications (chemical reaction mechanisms, tracing methods, kinetic isotopic effects). (P.A.)

No abstract available

[en] By-products formed in radiation-induced tritium labelling are identified by co-chromatography with authentic samples or by structure prediction using a quantitative structure-retention index relationship. The by-products, formed from labelling of steroids, polynuclear aromatic hydrocarbons, 7-membered heterocyclic ring structures, 1,4-benzodiazepines, 1-haloalkanes, etc. with activated tritium and adsorbed tritium, are shown to be specifically labelled and anticipated products from known chemical reactions. From analyses of the by-products, one can conclude that the hydrogen abstraction by tritium atoms and the substitution by tritium ions are the mechanisms of labelling. Classification of the tritium labelling methods, on the basis of the type of tritium reagent, clearly shows the active role played by tritium atoms and ions in radiation-induced methods. (author)

[en] Research highlights: → First principles lattice dynamics for 3d-metals hydrides are performed. → No phase transition in the hydrides under pressure is observed. → Atomic bonding in CoH is stronger than that in NiH. - Abstract: Ground state parameters and lattice dynamics of CoH and NiH phases are studied by means of the state-of-the-art ab initio pseudopotentials methods. Calculated ground state parameters and phonon DOS are in rather good agreement with available experimental data. No phase transformation for CoH and NiH was found in a wide pressure and temperature range.