Fluorbestimmung in biologischem Material mit dem Ringofen

Ohne Zusammenfassung     

Eine charakterisierung des steinersystems S(5, 8, 24)

S(5, 8, 24) is characterized as the unique Steiner system S(t, k, n) satisfying n = (t + 1)(k ? t + 1) and k ? t + 2 ? 4.     

Subgroups of a Direct Product of Groups that Satisfy the Strong Frattini Argument

We give criteria to characterize subgroups of a direct product of finite solvable groups that satisfy the strong Frattini argument.     

Mutually permutable subgroups and Fitting classes

Let G = AB be the mutually permutable product of the subgroups A and B. It is shown that if A and B are contained in a Fitting class , then the commutator subgroup G′ of G is also contained in . Received: 14 August 2006 Revised: 17 September 2006     

Field induced Increase of Pitch in Planar Cholesteric Liquid Crystals

In cholesteric liquid crystals the application of an electric field parallel to the helix axis can change the wavelength of selective reflection. For decreasing pitch of the studied mixtures, the colour shift becomes more stable against the field-induced transformation of the initial Grandjean structure into a confocal texture. In compounds with a low crossover frequency, a field induced increase of the pitch was observed at the switching between low and high frequency fields. The investigations allow new conclusions on the origin of the colour shift.     

Zur Chemie der Chlorthionitrenkomplexe des Rheniums Die Kristallstruktur von [N(SCl)2]⊕ [Re2Cl9]⊖

Chemistry of Chlorothionitrene Complexes of Rhenium. Crystal Structure of [N(SCl)₂]⊕ [Re₂Cl₉]? By reaction of S₃N₂Cl₂ with ReCl₅ the chlorothionitrene complex [ReCl₃(NSCl)₂]₂ is obtained in good yield; it has a dimer structure with chloro bridges. By the same reaction in POCl₃ solution the solvate [ReCl₃(NSCl)₂OPCl₃] is obtained. Instead, when a molar ratio of ReCl₅ and S₃N₂Cl₂ of 2:1 is taken, the product is [N(SCl)₂][Re₂Cl₉]. [ReCl₄(NSCl)OPCl₃] and excess PPh₃ react to give the nitrido complex [ReNCl₂(PPh₃)₂]. The crystal structure of [N(SCl)₂][Re₂Cl₉] was determined and refined with X-ray diffraction data (1021 independent reflexions, R = 0.031). It crystalizes in the space group C2/c with four formula units per unit cell (a = 1197, b = 1288, c = 1144 pm, ß = 107.83°). The [N(SCl)₂]⊕ cations have exactly C₂ and approximately C_2v symmetry; the NS bond lengths of 162 pm and the bond angles SNS (133.6°) and NSCl (117.6°) deviate considerably from the values of known [N(SCl)₂]⊕ structures. The [Re₂Cl₉]? anion consists of two face sharing octahedra and has a Re—Re distance of 270 pm. I. r. spectra of all compounds are reported and discussed.     

Kinks and rotations in long Josephson junctions

Kinks and rotations are studied in long Josephson junctions for small and large surface losses. Geometric singular perturbation theory is used to prove existence for small surface losses, while numerical continuation is necessary to handle large surface losses. A survey of the system behaviour in terms of dissipation parameters and bias current is given. Linear orbital stability for kinks is proved for small surface losses by calculating the spectrum of the linearized problem. The spectrum is split into essential spectrum and discrete spectrum. For the determination of the discrete spectrum, robustness of exponential dichotomies is used. Puiseux series together with perturbation theory for linear operators are an essential tool. In a final step, a smooth Evans function together with geometric singular perturbation theory is used to count eigenvalues. For kinks, non‐linear orbital stability is shown. For this purpose, the asymptotic behaviour of a semigroup is given and the theory of centre and stable manifolds is applied. Copyright © 2001 John Wiley & Sons, Ltd.