[en] The instrumental activation analysis is a technique relatively quickly that help to know the elemental composition of materials. It is used mainly in the trace elements determination but in the case of major elements it is necessary to make some considerations as the different nuclear reactions carried out due to the neutron flux is a mixture of thermal and fast neutrons. This could be interpreted for the presence and or erroneous quantification about some elements. In this work, is described the way in which was analyzed a container piece with approximately a 85% of aluminium. The elements Zn, Mn, Sb, Ga, Cu, Cl and Sm were determined. (Author)

[en] Radiochemical analysis of aragonitic fish otoliths provides a useful approach to validating ages obtained by more common methods. The history of applications of radiometry using short-lived natural isotopes to clams, Nautilus, living corals and fish otoliths is briefly reviewed. The biogeochemical assumptions required for successful use of these techniques are discussed, and the appropriate mathematical treatments required for data analysis are outlined. Novel normalization techniques designed to widen the validity of this approach are proposed. Desirable lines of further research are also briefly discussed. 38 refs., 1 tab

[en] We have developed a resin phase spectrophotometric method to determine the amount of beryllium by detecting a change in absorbance of the resin phase. 8-Hydroxynaphthalene-3,6-disulphonic acid-(1-azo-2')-1',8'-dihydroxynaphthalene-3',6'-disulphonic acid tetrasodium salt (beryllon II) immobilized by a strong base anion-exchange resin on the end of a bifurcated optical fibre bundle was chosen as a material sensitive to beryllium. Experiments were made using a home-made optical fiber spectrophotometer. The properties of the resin phase proved to be good for continual use of 350 times during a month. The reaction order between immobilized beryllon II and beryllium in solution was determined by kinetic theory and experiments. This method was also used to determine the amount of beryllium in beryllium-copper alloy; the response was linear from 0.43 to 2.60 μg/ml at pH 12.5 and 676 nm. The effect of interfering ions on the determination of beryllium was studied at the same time. (Author)

[en] The solvent extraction of lanthanum(III), europium(III), lutetium(III), scandium(III), and indium(III) in 0.1 mol dm^-3 sodium nitrate solutions with 2-thenoyltrifluoroacetone (Htta) in the absence and presence of tetrabutylammonium ions (tba⁺) into carbon tetrachloride was measured. The extraction of lanthanum(III), europium(III), and lutetium(III) was greatly enhanced by the addition of tba⁺; this could be explained in terms of the extraction of a ternary complex, M(tta)₄^-tba⁺. However, the extractions of scandium(III) and indium(III) were nearly the same when tba⁺ was added. The data were treated on the basis of the formation equilibrium of the ternary complex from the neutral chelate, M(tta)₃, with the extracted ion-pairs of the reagents, tta^-tba⁺, in the organic phase. It was concluded that the degree of association of M(tta)₃ with the ion-pair, tta^-tba⁺, is greater in the order La(tta)₃ ≅ Eu(tta)₃ > Lu(tta)₃, or that the stability of the ternary complex in the organic phase is higher in the order La(tta)₄^-tba⁺ ≅ Eu(tta)₄^-tba⁺ > Lu(tta)₄^-tba⁺. This is similar to those of adduct metal chelates of Htta with tributylphosphate (TBP) in synergistic extraction systems. (author)

[en] Polycrystal compounds KTcO₄ and RbTcO₄ at 296 K were studied by ³⁹K, ⁸⁷Rb and ⁹⁹Tc NMR pulsed method in the field of 7.04 Tl. ³⁹K and ⁸⁷Rb NMR spectra are characterized by quadrupole interaction of the second order, while ⁹⁹Tc NMR spectra present a multiplet structure at the expense of quadrupole interations of the first order. From analysis of electric field gradient (EFG), shape of lines cluster, coordination compounds, EFG tensor asymmetry parameters, dipole broadening and isotropic values of chemical shift were determined. Dependence of EFG in anionic and cationic positions on reciprocal volume of the unit cell is linear. Lattice and valency contributions of ⁹⁹Tc to EFG are evaluated

[en] Investigations into chemical and phase compositions of solid-phase products of H₃BO₃-NaVO₃-HNO₃-H₂O system depending on pH solution of sodium metavanadate and ratio of initial components in mixture of H₃BO₃ and NaVO₃ solutions, are carried out. It is determined that complex of 7Na₂O·B₂O₃·13V₂O₅·75H₂O formula whose composition is stable and does not depend either on ratio of initial components in the system or on pH medium, is formed in the studied system. On the basis of data of X-ray phase, thermographic analysis technique, IR and NMR spectroscopy the separated complex is attached to Na₇[B(OH)₃V₁₃O₃₆·6H₂O]·29,5H₂O formula. Using IR spectra identification the given compound is atteched to heteropolycompound on the basis of Keggin structure

[en] Molybdenum (5) fluorohalides: MoF₄Cl₂, MoF₄Cl, MoF_4.75Br_0.25, MoF₄Br, MoF₃Br₂, MoF_4.75I_0.25 are synthesized. Composition of saturated vapour over MoF_4.75Br_0.25 is determined by high-temperature mass-spectrometry

[en] A study was made on spectral-luminescent characteristics of zinc-borates with different structure, activated by Mn²⁺ ions, as well as on prospects of their practical use in gas-discharge indication panels (GIP). Spectral characteristics of zinc metaborate Zn₄O(BO₂)₆ and zinc orthoborate Zn₃(BO₃)₂ under VUV-excitation were investigated. The presented spectral-luminescent characteristics of zinc-borates, activated by Mn² ions, testify to the promising character of their use in GIP

[en] Investigation into ErNi interaction with hydrogen in the pressure region of < 1 MPa and at temperatures close to room ones is conducted using a differential automatic calorimeter. X -ray phase analysis of the reaction products allows one to consider that transformation of the source FeB structure in CrB takes place. Elementary cell parameters for ErNiH_3.6 are determined: a=0.3655 (3), b=1.1200 (8), c=0.4590 (5) nm. Dependence of differential enthalpy of hydrogen dissolution in ErNiH_x on x is studied. It is shown that in the region of 0 < x 1 < 1.0 and 1.0 < x < 3.0 compositions the differential dissolution enthalpies have constant values equalling respectively to -99.1 ± 0.7 and -90.6 ± 0.7 kJ/mol of H₂ErNi hydration enthalpy up to ErNiH_3,0 composition, equalling to -93 ± 1 kJ/mol of H₂ is calculated by dissolution differential enthalpy integration

[en] The character of thermal transformations of chromium (3), manganese (2), iron (3), cobalt (2), nickel (2), copper (2), lanthanum (3), cerium (3) and praseodymium (3) formates was studied by thermogravimetric method. In the course of lanthanum formate thermal decomposition in the range of 360-400 deg C oxocarbonate is formed, which at higher temperatures decomposes slowly to oxide. The process of the formate dehydration affect thermal stability of the salts owing to local hydrolysis of metal cation. A correlation between the temperature, corresponding to the maximum decomposition rate of d-element formates and their decomposition heat, was established