[en] The Co-Gd system was re-assessed using the CALPHAD technique. The solution phases (liquid, body-centered cubic, face-centered cubic and hexagonal close-packed) were described by the substitutional solution model. The temperature dependence of the interaction parameters of the liquid phase was separately expressed by the linear function and Kaptay equation. The intermetallic compounds Co₁₇Gd₂ and Co₅Gd, which have the same CaCu₅-type structure, were treated as one phase and described by a three-sublattice model (Co₂, Gd)(Co₂, Gd)₂Co₁₅, with Co₂ and Gd mixing on the first and second sublattices and the third sublattice occupied by Co. The other compounds (Co₇Gd₂, Co₃Gd, Co₂Gd, Co₃Gd₄ and CoGd₃) were treated as stoichiometric compounds. Two sets of self-consistent thermodynamic parameters of the Co-Gd system were obtained. (orig.)

[en] The Wythenshawe Boiler Rig in Manchester, UK, recently celebrated thirty years of operation in support of the UK nuclear power industry. The Boiler Rig, owned by EDF Energy and operated on EDF Energy's behalf by Serco plc, is a full scale once-through boiler test facility for the investigation of chemistry and corrosion related topics. This paper presents an overview of the design and operation of the Boiler Rig together with some of the technical highlights from its thirty years of operation, many of which have relevance to power plant operations beyond those plants for which the work was performed. (orig.)

[en] A self-consistent theory that describes charge density waves in a partially dielectrically gapped superconductor with d_x²-y²-pairing has been proposed. The dependences of dielectric, Σ, and superconducting, Δ, order parameters on the temperature and other problem parameters have been considered, and the phase diagram has been built. The corresponding angular diagrams for gap distribution over the Fermi surface have been plotted. The developed theory is used for the explanation of properties of high-temperature oxides. The influence of mismatch angle between the lobes of order parameters Σ and Δ on the gap distribution in the momentum space and the reentrance phenomenon for Σ with respect to temperature has been analyzed. (orig.)

[en] Cortical ^99mTc DMSA scintigraphy is accepted as a highly sensitive technique for the detection of regional lesions. It reflects accurately the histological changes and the interobserver reproducibility in reporting is high. Potential technical pitfalls should be recognized, such as the normal variants and the difficulty to differentiate acute lesions from permanent ones, or acquired lesions from congenital ones. Although DMSA scintgraphy seems to play a minor role in the traditional approach of urinary tract infection, recent studies suggest that this examination might influence the treatment of the acute phase, the indication of chemoprophylaxis and of micturating cystography, as well as the duration of follow-up. (orig.)

No abstract available

[en] The surface adsorption and reaction of water with PuO₂ thin films was investigated by X-ray and ultra-violet photoelectron spectroscopies (XPS and UPS, respectively). Initial motivation of the work was to further investigate the potential role of water in promoting the surface oxidation of PuO₂ to Pu(IV)/Pu(V) mixed oxides formerly discussed in literature which may seriously impede the stability of spent nuclear fuel. Water may act as oxidant, as catalyst for the oxidation by O₂, or as reactant leading to formation of hydrous oxide being oxidized by O₂ instead of PuO₂(cr). In order to obtain high water coverage under the experimentally required ultra-high vacuum conditions, water was adsorbed at low temperature (77 K) as thick ice film. Results were compared to thin water layers adsorbed at room temperature. When adsorbed at 298 K, water dissociates forming a thin hydroxyl (OH^-) layer with small amounts of molecularly adsorbed water but no further reaction (in the sense of oxidation or reduction) is detected. At 77 K, water condenses as ice film. Here, a mainly non-dissociative adsorption of water is observed for layers ∝ 1 ML while for higher dosages, only molecular water/ice is observed and no significant contribution of OH (in the water layers) is detected. When exposing the sample to UV light while warming it up, the ice layer thaws and desorbs leaving behind a Pu₂O₃ surface. This surprising reduction of PuO₂ stands in sharp contrast to the radiolytically driven oxidation of spent fuel in presence of water. It is discussed in terms of a photochemically driven interface reaction. (orig.)

[en] Green rust is an Fe(II)-Fe(III) layered double hydroxide that can be present in groundwater in roch formations where long term nuclear waste repositories are being planned. Green rust (GR) is redox-active, making data for its behaviour a necessity in safety assessment modeling because the mobility of many elements, including radionuclides, is controlled by redox reactions. In this paper, we compare the influence of geometry and charge of three redox active ions on their reaction with colloidal size particles of green rust sodium sulfate (GR_Na,SO4). Pentavalent neptunyl, selenite and chromate all have different geometries and valence states. Ions with shape and charge similar to SO₄^2-, the GR_Na,SO4 interlayer anion such as, for example, CrO₄^2-, diffuse into the GR interlayer where electrons are readily transferred, and the element may become incorporated into the final oxidised product. More often, the geometry and/or charge of the ion differ significantly from the interlayer anion, such as is the case for SeO₃^2- and NpO₂^-. These are reduced at the exterior of the flat hexagonal GR crystals, primarily at the edges. Se(IV) is reduced to Se(0) and precipitates as a separate phase, while Np(V) is reduced to Np(IV) and precipitates possibly as NpO₂ or as a substitute in an iron oxide. Whether it adsorbs to pore walls in the groundwater flowpath, or it travels as a colloid, green rust can have a significant effect on radionuclide mobility in the near and far field of repositories. (orig.)

[en] We propose two supersymmetric standard models (SMs) with decaying and stable dark matter (DM) particles. To explain the SM fermion masses and mixings and have a heavy decay DM particle S, we consider the Froggatt-Nielsen mechanism by introducing an anomalous U(1)_X gauge symmetry. Around the string scale, the U(1)_X gauge symmetry is broken down to a Z₂ symmetry under which S is odd while all the SM particles are even. S obtains a vacuum expectation value around the TeV scale, and then it can three-body decay dominantly to the second/third family of the SM leptons in Model I and to the first family of the SM leptons in Model II. Choosing a benchmark point in the constrained minimal supersymmetric SM with exact R parity, we show that the lightest neutralino DM is consistent with the CDMS II experiment. Considering S three-body decay and choosing suitable parameters, we show that the PAMELA and Fermi-LAT experiments and the PAMELA and ATIC experiments can be explained in Model I and Model II, respectively. (orig.)

[en] The energy centroids and integrated strengths of Gamow-Teller transitions in the β⁺ and electron-capture decay are analyzed for nuclei whose proton number Z and neutron number N are restricted to 44 ≤Z≤ 50 and 50 ≤N≤ 58. The analysis is based on data measured both with high-resolution γ -ray spectrometry and total γ -ray absorption techniques. The dependence of the considered quantities on the relative neutron excess are established after taking into account the effects due to the Coulomb interaction and mean-field level occupancies. An extrapolation of this dependence to the lightest known tin isotopes is used to estimate the decay characteristics of ¹⁰⁰Sn and ¹⁰¹Sn. The values extrapolated for the half-lives of ¹⁰⁰Sn and ¹⁰¹Sn agree with experimental data. Using the extrapolated values together with shell model predictions, the Q values for the electron-capture decay of ¹⁰⁰Sn is evaluated. The quenching factor for β⁺ and the electron-capture decay of the nuclei under consideration here is established to be 0.56(2) with a possible weak dependence on N-Z. (orig.)

[en] Excitation functions of elastic ²⁸Si+α scattering were measured employing the relatively new thick-target inverse kinematics technique, confirming the usefulness of the method. Data were taken at a ²⁸Si beam energy of 150MeV in a reaction chamber filled with ⁴He gas, corresponding to the excitation region of 10-24MeV in ³²S. Results are compared to earlier studies, in order to validate the method and explore its limitations. The data were treated in the framework of a simplified R -matrix approach. Energies, widths and spin assignments were obtained for 129 resonances in this mid-shell nucleus. The structure is discussed within the concept of α -cluster structure in the quasi-continuum of ³²S. (orig.)