[en] The problem of postirradiation heart injury is discussed. The experimental data as well as clinical one are reviewed. The changes in electrocardiogram are described. (A.S.)

[en] It has been shown that the change of the number of electrons in nickel impurity centres in NaCl induced relatively large shift of one-electron energy levels and, therefore, the long-time existence of such transformed centres seems rather improbable. The newly formed centres, observed in irradiated NaCl:Ni²⁺ crystals, must be more complicated than the single ions with reduced or enhanced valency. The valency stabilization effect of the host lattice can come our from the change of metal-ligand distance or from some complicated distortion in which the compensating cation vacancy can also take part. (author)

[en] The core of the MAGNETOM diagnostic device is a liquid helium-cooled cryogenic magnet, having the shape of a hollow cylinder about 2 m long, 50 to 60 cm i.d. Its inner space is designed to accommodate a bench with the patient, whose part examined, usually the head, is enclosed in a smaller coil and is located roughly in the center of the magnet. The examination takes 4 to 20 minutes, during which the patient must be fixed to prevent any motion. Inhalation anesthesia with spontaneous ventilation using the Jackson-Rees or Bain's system and a laryngeal mask is considered the safest way where no special equipment is employed. If artificial ventilation is necessary, balanced anesthesia with either manual ventilation using Bain's system or a fluidic type ventilator seems to be the best choice. The preparation of the patient prior to the examination, the premedication, and the monitoring equipment are described. (J.B.). 1 tab., 5 figs., 11 refs

[en] The electronic structure of ACu₂O₃ compounds [A=Ca,Mg] has been calculated within the local density approximation (LDA) and compared with recent magnetic neutron scattering data. Both compounds deviate markedly from the usual pdσ cuprate picture. Strong interlayer exchange is found to be responsible for the missing spin gap generic for ideal two-leg ladders (TLL). Hence, they can be modelled as weakly coupled anisotropic bilayers

[en] The hot laboratories for mechanical testing at the Nuclear Research Institute Rez provide all the necessary preparatory work for mechanical tests together with visual inspection, fractography and dimension measurements, required to identify the effects of irradiation on the mechanical properties of reactor pressure vessel surveillance specimens. (P.A.)

[en] Electron energy-loss spectroscopy in transmission has been used to study the electronic excitations near the excitation onset of a number of low dimensional cuprate structures. It is shown that the spectral weight of the lowest lying charge transfer excitation significantly depends upon the dimensionality of the cuprate network, i.e., on the degree of delocalization of the involved electronic states. Furthermore, a detailed analysis of the lowest lying charge transfer excitation as a function of momentum and polarization reveals convincing evidence for the existence of two different types of charge transfer excitation located near the spectral onset. This can only be modelled with the inclusion of Cu and O orbitals beyond the standard pdσ extended Hubbard model which is widely used for the description of electronic properties of Cu-O networks. To the best of our knowledge this is the first experimental manifestation for the relevance of orbitals beyond the standard extended Hubbard model for the low-energy excitations in a cuprate

[en] Paper summarizes results of surveillance specimens programmes of WWER-440/V-213C type reactors. Comparison of transition temperature shifts, induced by irradiation, and determined from impact Charpy V-notch toughness as well as from static fracture toughness tests on pre-cracked Charpy size specimens (COD) is given. Two methods have been used for determination of static fracture toughness shifts - standard COD type specimens from a standard surveillance programmes and reconstituted COD type specimens from broken halves of Charpy V-notch specimens. Results obtained are discussed from the point of view of irradiation conditions as well as of different type of testing. (author)

[en] A low temperature lattice modulation of the chains of the YBa₂Cu₃O₇ is considered by deriving a Hamiltonian of electron-lattice interaction from density-functional calculations for deformed lattice and solving it for the groundstate. Hubbard-type Coulomb interaction is included. The obtained groundstate is a charge-density-wave state with a pereodicity of four lattice constants and a gap for one-electron excitations of about 1eV, sensitively depending on parameters of the Hamiltonian. There are lots of polaronic and solitonic excitations with formation energies deep in the gap, which can pin the Fermi level and thus produce again metallicity of the chain. They might also contribute to pairing of holes in adjacent CuO₂-planes. (author)

[en] The results of surveillance specimen programmes for VVER-440/V-213C type reactors are summarized. A comparison is given of the transition temperature shifts induced by irradiation and derived from impact Charpy V-notch toughness as well as from static fracture toughness tests on pre-cracked Charpy size specimens (COD). Two methods were used to determine the static fracture toughness shifts: standard COD type specimens from the standard surveillance programmes, and reconstituted COD type specimens from broken halves of Charpy V-notch specimens, whereby identical irradiation conditions were assured. The results show that the transition temperature shifts from static tests are generally larger than those from dynamic tests. (P.A.)

[en] Quasi one-dimensional magnetic chain compounds with nearest-neighbor exchange J₁ and next-nearest-neighbor exchange J₂ exhibit a quantum critical point (QCP) for the ratio J₂/J₁=-0.25. The recently synthesized compound Li₂ZrCuO₄, which contains spin-1/2 chains of distorted, edge shared CuO₄ plaquettes, is close to this QCP and shows therefore a strong field dependence of the thermodynamical properties. From fits to the measured susceptibility and specific heat, a ratio J₂/J₁∝-0.3 was determined. Here, we present a detailed study of the electronic and magnetic properties of Li₂ZrCuO₄ based on density functional calculations. We combine results of LDA calculation, which were mapped onto an effective one-band tight-binding model and subsequently to an extended Heisenberg model with exchange integrals derived from total energy differences for constraint magnetic states using LDA+U. The influence of (i) the deviation from the standard, planar CuO₄ geometry and (ii) the experimentally observed Li disorder was carefully investigated. We find J₂/J₁∝-0.25±0.03 very close to the QCP. In addition, we obtain a sizeable inter-chain coupling J _{perpendicularto} ∝7 K playing an important role for the saturation field due to the vicinity of the QCP. (orig.)