[en] ¹¹B NMR chemical shifts and linewidths have been measured in very dilute aqueous solutions of boric acid and borates. The results can be explained by taking pH dependent weighted averages over the species B(OH)₃ and B(OH)₄^-. The ¹¹B-¹⁰B primary isotope effect on the magnetic shielding is smaller then 3x10^-8. The H₂O-D₂O solvent isotope effect on T₁ has been established for ¹¹B and ¹⁰B in the species mentioned, and from the ratios of T₁ the quadrupolar origin of the relaxation mechanism has been inferred. (orig.)

[en] The structure factors of molten LiNO₃, RbNO₃ and AgNO₃ and the 1:1 LiNO₃-RbNO₃ mixture have been determined over a wide range of momentum transfer by neutron total scattering measurements using a pulsed spallation neutron source. Least-squares analyses applied to the intra-ionic part of the structure factors have revealed the geometry of nitrate ions to be equilateral triangular (the Dsub(3h) symmetry) in the melts, independent of the cations involved. The radial distribution function (RDF) of the AgNO₃ melt has indicated that about four nitrate ions are bound to an Ag⁺ ion as a monodentate ligand with the shortest Ag-O distance of 240 pm. The contact between lithium atoms and nitrate ions was also evidenced at about 190 pm in the RDF of the melts containing lithium ions, but the orientation of the nitrate toward lithium ions was not conclusive in the present study. (orig.)

[en] The equivalence of magnetic field line equations to a one-dimensional time-dependent Hamiltonian system is used to construct magnetic fields with arbitrary toroidal magnetic surfaces I = const. For this purpose Hamiltonians H which together with their invariants satisfy periodicity constraints have to be known. The choice of H fixes the rotational transform eta(I). Arbitrary axisymmetric fields, and nonaxisymmetric fields with constant eta(I) are considered in detail. Configurations with coinciding magnetic and current density surfaces are obtained. The approach used is not well suited, however, to satisfying the additional MHD equilibrium condition of constant pressure on magnetic surfaces. (orig.)

[en] A fast energy wave packet pulse with a velocity greater than 10⁸ cm/s has been generated from a T-shock tube, accompanying the discharge current disruption and a sharp voltage peak. The distribution of the disrupted wave increases the plasma temperature by 5 eV, and the density jumps to 2-3 times its initial value. The disruption wave streams through the proceeding plasma and shock wave without noticeable dissipative interaction. The production of a backward shock wave has been referred to the destruction of the wave at the expansion chamber. A propagated magnetosonic wave with a velocity of 6x10⁵ cm/s has been detected, which was excited near the discharge electrodes. (orig.)

[en] The deuterium spin-lattice relaxation time, T₁, of H₂O/D₂O mixtures is measured at 298.2 K. The relaxation rate, T₁^-1, is found to increase with increasing deuterium atom fraction, n, the plot of T₁^-1 vs. n exhibiting a small depature from linearity. A general equation T₁^-1 (n) for the H₂O/D₂O system is formulated. The temperature dependence of T₁ is investigated in the temperature range 278.2 K to 298.2 K for n=6.8x10^-3, 6.8x10^-2, 0.244, 0.500, and 0.997. On the assumption that the electric field gradient parameters (e² q Q/h and delta) are independent of n and temperature, an effective correlation time, tausub(c,eff,) is derived from the T₁ data. Relatively large isotope effects on tausub(c,eff) are found; possible reasons for the existence of such isotope effects are discussed in terms of a simple Debye model. The mean activation enthalpy (Δ sup(not equal) H) and entropy (Δ sup(not equal) S) for the relaxation process within the temperature range studied are derived on the basos of Eyring's absolute rate theory and the temperature dependence of tausub(c,eff). Both activation parameters are found to increase linearly with n: Δ sup(not equal) H/kJ mol^-1=18.2+2.46 n, Δ sup(not equal) S/JK^-1 mol^-1=37.5+6.77 n. (orig.)

[en] The separation coefficient of copper isotopes, ⁶³Cu and ⁶⁵Cu, in the electromigration process through cation exchange membrane was experimentally determined as 3.2x10^-4. The appropriate heating condition of low ionizing filament current for thermo-ionization mass spectrometry was developed and this method was applied to the copper isotope analysis in the present work. Due to the high ionization potential of copper there have been difficulties in using the double-filament thermo-(or surface) ionization method in the mass spectrometric analysis of copper. Instead one has used ionization by electron bombardment or thermo-ionization with the copper electro-plated on filaments. In the present work a simple and convenient method of copper isotope analysis has been developed and successfully applied to copper samples taken from an exchange electromigration experiment. (orig.)

[en] Quasicrystalline Al-16 at-%V was transformed to the amorphous state by low-temperature electron irradiation in a high-voltage electron microscope. Electron diffraction experiments were carried out in the amorphous state and in the crystalline state obtained after subsequent heat treatment. From the results the total structure factor was determined. The pair correlation function was calculated which yields the radii of the different coordination spheres and the total coordination number. The results are discussed in terms of current topological models of the structure of metallic glasses. (orig.)

[en] Calcium ions were made to electromigrate along a cation exchange membrane. The abundance ratios of the calcium isotopes (Ca-40, 42, 43, 44, 48) in the migrated bands were measured by thermo-ionization mass spectrometry. The lighter isotopes were enriched in the front part of the migrated band. The increments in the isotope abundance ratios were found to be proportional to the mass difference of the isotopes. The observed epsilon-values per unit mass difference (epsilon/ΔM) were 1.26 x 10^-4 (at 20⁰C), 1.85 x 10^-4 (at 25⁰C) and 2.4 x 10^-4 (at 40⁰C). The mass spectrometry was improved by using a low temperature for the evaporation of CaI₂. (orig.)

[en] Perturbation method, using the properties of SO (2, 1) algebra is applied to get a simple analytical formula for energy eigenvalues of the exponential cosine screened Coulomb potential. (orig.)

[en] By activation of the new host lattices Ba₂La₂B²⁺Te₂O₁₂ (B=Zn,Mg) with trivalent rare earth ions Ln³⁺ = Pr, Sm, Eu, Tb, Dy, Ho, Tm an emission in the visible region is observed. The influence of the electronic structure and concentration on the relative emission efficiency as well as the host lattice participation in the energy transfer processes are discussed. (orig.)