The detection of oxygen in magneto-optical layers with SIMS

The detection of oxygen in magneto-optical layers is of fundamental importance for the characterization of the stability of RE-TM material. The magnetic properties are directly influenced by oxide formation. Oxygen depth profiles are carried out by using the SIMS technique. A comparison with magnetic measurements showed a clear conformity. We were able to study the oxidation behaviour of various layers at room temperature and at higher values up to 250° C for several hours. It could be shown that aluminum is a successful material for the protection of RE-films against oxidation. The difficulties of translating SIMS counting rates into concentration values were overcome by using EPMA. Specially prepared reference samples were measured by this technique and could then be used as standard samples for SIMS.     

Darstellung und Eigenschaften von π-Cyclopentadienylrhodium-bis(tert.-phosphit)-Komplexen

The half-sandwich type compounds C₅H₅Rh[P(OR)₃]₂ (R = CH₃, C₂H₅, C₆H₅, p-CH₃C₆H₄, p-ClC₆H₄) have been prepared from [(P(OR)₃)₂RhCl]₂ and NaC₅H₅. The NMR. data as well as the IR. and mass spectra of the new compounds will be discussed. The preparation of C₅H₅Rh(CO)P(OC₂H₅)₃ is also reported.     

A stable binuclear complex containing PdHPd bonds

The preparations of the binuclear hydrido-bridged cations [(terdentate ligand)Pd(μ-H)Pd(terdentate ligand)]⁺ from [(terdentate ligand)Pd(acetone)]⁺ and NaO₂CH and [(terdentate ligand)Pd(μ-H)Pt(terdentate ligand)]⁺ from [(terdentate ligand)Pd(acetone)]⁺ and [(terdentate ligand)PtH] (terdentate ligand = 2,6-(Ph₂PCH₂)₂C₆H₃) are reported. The preparation of the cation [(terdentate ligand)Pt(μ-H)Pt(terdentate ligand)]⁺ is also reported.     

Multiscale damage analyis for steel structures

An approach to model the deterioration of steel structures is presented by transferring the results of a continuum damage mechanics analysis to an extended beam model which can account for the loss of structural integrity. Damage starts at the microscopic level by the initiation, growth and coalescence of voids with decreasing material resistance followed by the formation of microcracks at the mesoscale. Nevertheless, the material behavior can be sufficiently modelled on a phenomenological basis taking into account viscoplasticity, hardening effects and damage evolution. The associated model parameters are identified with the help of an evolutionary algorithm adapting numerical to experimental results. Using the finite element method a nonlocal formulation of the damage variable is required to obtain mesh-independent results by structural analysis. The maximum element size is limited by the small magnitude of the internal length. Therefore, numerical analyses of large scale 3D steel structures are computationally expensive. To reduce the effort a beam element is proposed to account for the plastic hinges and the loss of resistance in the course of damage evolution. The corresponding relationship of bending moment and curvature bases on the continuum damage mechanics model. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Perfect double covers with paths of length four

It is shown that for any 4-regular graph G there is a collection F of paths of length 4 such that each edge of G belongs to exactly two of the paths and each vertex of G occurs exactly twice as an endvertex of a path of F. This proves a special case of a conjecture of Bondy. © 1996 John Wiley & Sons, Inc.