[en] A radiochemical displacement method has been developed for the determination of trace amounts of indium using radioactive zinc dithizonate as the reagent. The ease with which indium can be quantitatively collected over ferric hydroxide is put to advantage in developing the above method. The collection method in conjunction with the radiodisplacement method is used to determine indium in fluedust and zinc ore. The method is sensitive down to 2 μg indium in 10 ml of aqueous volume. (orig.)

[en] U(VI) can be efficiently determined in the range 0.3-10mM after its separation from Th(IV), Zr(IV), Al(III), Fe(III), lanthanides and other ions by ion-pair liquid chromatography on a 3 x 150 mm glass column packed with Separon SGX C18 modified with sorbed ammonium dodecyl sulphate. Traces of uranium can be preconcentrated directly on the analytical column from acidified water solutions and separated from Th, Zr, Al, Fe, lanthanides and other elements, with an enrichment factor of ∼100 and recovery of 98±8%, by isocratic of pH or concentration gradient elution with ammonium 2-hydroxy-2-methylpropionate or ammonium citrate solution. Post-column derivatization with 25μM Arsenazo III in 0.1M formate buffer at pH 2.7 is used for detection and quantification. (author)

[en] Single crystals were prepared by way of chemical transport, of the compounds LaSe_1.9, GdSe_1.875, DySe _1.875, and HoSe_1.875. Their chemical structure was analysed by a complete crystal structure analysis by means of the Guinier and the precession method, by four-cycle diffraction analysis, and by anisotropic structural refinement. Furthermore, monocrystals or powders were synthetized of lanthanide selenide orthosilicates present as the compounds Ln₂ Se SiO₄ (Ln = La, Ce, Pr, Nd, Sm, Dy, Ho), and Ln₂ Se₃ Si₂ O₇ (Ln = Ce, Pr, Nd, Sm, Gd). Their space groups and their lattice constants were determined. (KW)

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[en] The reduction behavior of powdered Fe-Ni oxides in a hydrogen atmosphere at 380^oC was studied by means of radioactive tracer of ⁶³Ni. Change in the radioactivity of the surface gives information on mutual diffusion of Fe and Ni between surface and bulk during the reduction process. The radioactivity of ⁶³Ni in the surface layer of the alloy oxides increased with the progress of reduction in the initial stages and then drastically decreased, suggesting that Ni is covered with metallic Fe at the final stage of reduction. x-Ray diffraction showed that unreduced Fe-Ni oxides were composed of a mixture of Fe₂O₃ (hematite) and NiO, and the reduced alloys were composed of homogeneous Fe-Ni and Fe or Ni. Fe₂O₃ was changed to Fe₃O₄ (magnetite) before metallic Ni appeared, and metallic Ni appeared earlier than Fe-Ni. Metallic Fe appeared after Fe-Ni, and no FeO was detected throughout the reduction. The following reactions were proposed to be involved in the reduction mechanism; FeO+Fe₂O₃→Fe₃O₄ and NiO+Fe+Fe₂O₃→Ni+Fe₃O₄. It was also concluded that an Fe-rich surface is formed by the belated diffusion of Fe to metallic Ni, which is produced earlier than metallic Fe. (author)

[en] The homo- and heteropolychalcogenide anions, Ch_n^2- (n = 1, 2, 3, 4; Ch = Se and/or Te) and the hydrochalcogenide anions, HCh^-, have been prepared and characterized in solution by ¹H, ⁷⁷Se, ¹²³Te and ¹²⁵Te nuclear magnetic resonance spectroscopy. The polychalcogenide anions were prepared in ethylenediamine and/or liquid ammonia by the reaction of the alkali-metal monochalcogenide with the appropriate chalcogen in the presence or absence of 2,2,2-crypt or by the direct reaction of the alkali metal with the chalcogen in liquid ammonia. With the exception of the pyramidal shaped TeSe₃^2- anion, the polchalcogenide anions have open-chain structures. In addition, the more electronegative selenium atoms are found to be in terminal positions in the heteropolychalcogenide anions Te_nSe_3-n^2- and Te_mSe_4-m^2- (n = 1,2; m = 2, 3), which can be rationalixed by using the topological charge stabilization rule. The chemical shifts and unusually large spin-spin coupling constants are reported for the polychalcogenide anions and their trends discussed. 52 refs., 6 figs., 3 tabs

[en] This review article deals mainly with the reactions of radioactive ¹³N atoms (t_1/2 = 10 min) with inorganic and organic compounds, both in the gaseous and condensed phases. Some information is also included regarding the reactions of stable thermal ground-state (⁴S) and electronically excited (²D, ²P)¹⁴N atoms with simple gaseous compounds. (author)