FEM study of palladium and molybdenum clusters on an alumina covered field emitter

Palladium and molybdenum polycrystalline layers (clusters) have been deposited in a stainless steel UHV system onto a layer of alumina (Al₂O₃). This layer has been prepared by high temperature oxidation of an aluminium layer. The interaction of this system with nitrogen has been investigated at room temperature by an FEM technique. Under these conditions nitrogen spillover from molybdenum to palladium has been observed.     

Diffusion Structural Analysis Study of Titania Films Deposited by Sol-Gel Technique on Silica Glass

The diffusion structural analysis (DSA) was used to characterize microstructure changes of hydrous titania gel films under in situ conditions of heating. TG and DTA were used in order to elucidate the processes controlling the formation of anatase film during heating of hydrous titania gel film. The annealing of porosity and near surface structure defects of the dehydrated titania films was indicated by DSA in the temperature range 255–700°C as the decrease of radon release rate. It was demonstrated that the annealing was enhanced on heating in oxygen in comparison with heating in argon. The DSA experimental results were compared with model curves describing the radon diffusion mobility and the annealing of radon diffusion paths.     

Preface

This issue of Journal of Thermal Analysis and Calorimetry contains selected papers based on presentations in the field of thermal characteristics of advanced polymer systems presented at the 8^th International Symposium on Polymers for Advanced Technologies (PAT 2005) held in Budapest, September 2005. Guest Editors     

Projectivep-algebras

Presented by R. Freese.     

Multiple-scattering-theory analysis of XANES spectra of SO2 adsorbed on Cu(100)

The sulphur K-edge x-ray absorption spectra of SO₂ multilayer and of SO₂ submonolayer adsorbed on Cu(100) are analysed. It is found that the dominant spectral features are of a molecular origin. The results support earlier findings that the SO₂ molecule stands perpendicular to the surface. Use of non-selfconsistent potentials does not lead to a good quantitative agreement between theory and experiment.     

Density Correlations in the Two-Dimensional Coulomb Gas

We consider a two-dimensional Coulomb gas of positive and negative pointlike unit charges interacting via a logarithmic potential. The density (rather than the charge) correlation functions are studied. In the bulk, the form-factor theory of an equivalent sine-Gordon model is used to determine the density correlation length. At the surface of a rectilinear plain wall, the universality of the asymptotic behavior of the density correlations is suggested. A scaling analysis implies a local form of the compressibility sum rule near a hard wall. A symmetry of the Coulomb system with respect to the Möbius conformal transformation, which induces a gravitational source acting on the particle density, is established. Among the consequences, a universal term of the finite-size expansion of the grand potential is derived exactly for a disk geometry of the confining domain.     

Use of new composite materials for the determination of Cu, Cd, Mo, As, and Sb in biological samples by radiochemical neutron activation analysis

Summary  Vezetéknév     

A multivalued version of Sharkovskiĭ’s theorem holds with at most two exceptions

A multivalued version of Sharkovskiĭ’s theorem is formulated for M-maps on linear continua and, more generally, for triangular M-maps on a Cartesian product of linear continua. This improves the main result of [AP1] in the sense that our multivalued analogue holds with at most two exceptions. A further specification requires some additional restrictions. For instance, 3- orbits of m-maps imply the existence of k-orbits for all k ? \mathbbNk \in {\mathbb{N}} , except possibly for k ?k \in {4, 6}. It is also shown that, on every connected linearly ordered topological space, an M-map with orbits of all periods can always be constructed. This demonstrates that Baldwin’s classification of linear continua in terms of admissible periods [Ba] is useless for multivalued maps.     

Influence of boric acid on the electrochemical deposition of Ni

The electrolytic deposition of Ni onto a paraffin-impregnated graphite electrode from supporting chloride electrolyte (0.5 mol dm⁻³ NaCl) adjusted to the required pH using dilute HCl is investigated. The effect of electrolyte composition on the Ni electrodeposition is studied using linear sweep voltammetry in the cathodic region. An elimination voltammetry procedure was applied to evaluate the polarization curves. The aim of this work was to deduce the mechanism of Ni reduction in the chloride bath as well as the influence of boric acid on this. Positively-charged NiCl⁺ ions were found to be the electroactive particles in the Ni reduction mechanism. The strong competition between the NiCl⁺, Cl⁻ and H⁺ ions for active sites at the electrode is discussed. Kinetically-controlled adsorption/desorption processes of various species were also confirmed using elimination voltammetry with a linear scan. The evolution of gaseous hydrogen, catalyzed by the freshly-deposited Ni, accompanies the electrodeposition process. The presence of boric acid at a sufficiently high concentration inhibits the deposition of Ni and, at the same time, improves the morphology and brightness, as well as the adhesion of the deposited Ni. Elimination voltammetry with a linear scan is an efficient way to evaluate current–potential curves that reflect the electrodeposition of one-component Ni coatings. By eliminating selected currents, additional interesting and useful information can be obtained from voltammetric data.