Kb/Ka X-ray intensity ratios in calcium and potassium compounds

Summary Kb/Ka X-ray intensity ratios of some K and Ca compounds were studied. The samples were excited with 59.5 keV g-rays emitted from 75 mCi ²⁴¹Am radioisotope source and characteristic K X-ray from the samples were counted by means of an Si(Li) detector which has a resolution 155 eV at 5.9 keV. We found that Kb/Ka X-ray intensity ratios are changed by chemical effect for different K and Ca compounds. The experimental values were compared with the calculated theoretical values for elemental K and Ca.     

Extraction of barium picrate into nitrobenzene in the presence of benzo-15-crown-5

From extraction experiments with ¹³³Ba as a tracer, the extraction constant corresponding to the equilibrium Ba²⁺(aq) + 2A^-(aq) + 2L(nb) BaL₂ ²⁺(nb) + 2A^-(nb) in the two-phase water-nitrobenzene system (A^- = picrate, L = benzo-15-crown-5; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (BaL₂ ²⁺, 2A^-) = 5.7. Furthermore, the stability constant of the benzo-15-crown-5 - barium complex in nitrobenzene saturated with water was calculated: log b_nb (BaL₂ ²⁺) = 14.6.     

Highest-weight representations ofsl(2, ℂ) andsl(3, ℂ) via canonical realizations

The infinite-dimensional representations of thesl(n+1, ) Lie algebras (maximal representations) constructed in our previous paper are studied on the two simplest examplesn = 1,2. The sufficient condition for irreducibility of the maximal representations is proved to be also necessary in these cases. It is further shown, that our method allows us to construct other set of infinite-dimensional highest-weight representations ofsl(3, ), so calledmixed representations which are irreducible in some cases when the maximal as well as the standard highest-weight representations (Verma modules) are reducible.Dedicated to the 25th anniversary of the Joint Institute for Nuclear Research.The authors are grateful to Prof. A. A. Kirillov, Dr. A. U. Klimyk, Dr. W. Lassner and Prof. D. P. Zhelobenko for stimulating discussions.     

On states on the product of logics

We take up the question of when a state (= -additive measure) on the product of logics (=-orthomodular posets) depends on at most countably many coordinates. We show that it is always so provided there are no real-measurable cardinals. The manner of dependence is a kind of convex combination. We derive some consequences of the latter statement.     

The infrared spectra of solid solutions of some iron and chromium oxides

Oxides Fe_2–x Cr _x O₃ (corundum-type) and Fe_3–y ,Cr _y O₄ (spinel-type) were studied by transmission IR spectroscopy. The wavenumbers corresponding to characteristic absorption maxima depend linearly on the composition of both types of solid solutions, i.e. onx andy. The results show that IR spectroscopy can contribute to the analysis of solid solutions of iron and chromium oxides and of the oxidation products of Fe-Cr alloys.The authors are indebted to Ing. P. Holba for the preparation of synthetic oxide samples. The cooperation of Yu. Borodkin and I. Zuika (Riga) who made the measurements in the far IR region is gratefully acknowledged.     

Production of lepton pairs in processes with hadronic jets

We propose a model for the production of extra (additional) lepton pairs in deep inelastic lepton-hadron scattering, e⁺e^– annihilation and large p_T processes. Extra lepton pairs are supposed to be originated by annihilations of quarks and antiquarks created during the space-time evolution of quark initiated jets. This mechanism yields predominantly dileptons with rather low masses. Predictions following from the model are compared with the recent data on trimuon production in neutrino-nucleon interactions. It is also suggested that internal hard processes can lead to dileptons with both small and large masses. The latter mechanism has rather small cross section but it is particularly interesting from the point of view of the simple quark-parton model.Dedicated to Academician Václav Votruba on the occasion of his seventieth birthday.     

Influence of the overall pressure on electrical conductivity of the amorphous semiconductor Ge15Te81S2As2

The experimental results obtained with the chalcogenide glass Ge₁₅Te₈₁S₂As₂ with imposed overall pressure up to 700 MPa are presented. The material exhibits the switching effect and the memory effect. It is shown that the overall pressure changes remarkably d.c. electrical conductivity of the amorphous semiconductor. It is assumed that the changes in conductivity are caused by changes in activation energy. The changes in activation energy within the range of considered pressures are, as follows from our measurements, E/p–10·95×10^–5 eV/MPa +p × 10·41 W 10^–7 eV/MPa². The assumption of the activation energy dependence on pressurep are confirmed also by measurements of dependence In vs. 1/T at various pressures.     

Induction period of the calcium nitrate-water system

The induction period-supercooling dependence was measured in calcium nitrate-water system within the concentration range 1.5–23 mol% of Ca(II). It was found that the behaviour of the system may be described by the equations for transformation kinetics with the use of classical theory of homogeneous nucleation in glasses. From the experimental data values of interfacial tension of the liquid-solid interface were calculated and correlated qualitatively with the observed stability of the studied system with respect to crystallization.     

Evaporation of doped NaCl crystals

In the present paper an investigation of the influence of impurity ions on the evaporation of NaCl crystals is reported. Monovalent impurities little influence the evaporation rate. The evaporating structures have changed only when there were extremal differences in the values of ionic radii. However, the bivalent impurities substantially influence the evaporation rate. This unfluence depends upon the fact whether the impurities are in non-associated or associated state with cation vacancies, respectively. This fact also affects the shape of evaporating structure.     

Extraction and DFT study on the complexation of the methylammonium cation with a hexaarylbenzene-based receptor

In methods for quantification of ⁶³Ni, in e.g. reactor coolant water, a chemical separation is required due to ⁶³Ni being a pure beta emitter with limited means of quantification. ⁶⁰Co, a common radionuclide in reactor coolant water, is not completely separated with the commonly used separation procedure, and it is not resolved from ⁶³Ni in the beta spectrum. The separation method discussed in this work consists of TRU resin (Eichrom) and Ni resin (Eichrom). After running the separation procedure, depending on the initial activity of ⁶⁰Co, there may still remain enough ⁶⁰Co to interfere in the measurement of ⁶³Ni. The ⁶⁰Co interference is corrected for via a gamma spectrometric measurement. This correction may, depending on the ⁶³Ni/⁶⁰Co ratio, introduce a large contribution to the measurement uncertainty. The aim of this work was to evaluate the possibility to reduce the measurement uncertainty of ⁶³Ni measurements by adding a second Ni separation to the method. Double Ni separations were performed on reactor coolant water having a ⁶⁰Co activity much higher than the ⁶³Ni activity (⁶³Ni/⁶⁰Co = 0.01), in order to decrease the radioactivity of ⁶⁰Co in the sample. The measurement uncertainty of the ⁶³Ni measurement result was reduced by a factor of about three.