On K-Loops Of Finite Order

In this note we undertake an axiomatic investigation of K-loops (or gyrogroups, as A.A.Ungar used to name them) and provide new construction methods for finite K-loops. It is shown how, more or less, the axioms are independent from each other. Especially (K6) is independent as A.A. Ungar already had conjectured. We begin with right loops (L,⊕) and add step by step further properties. So the connection between K-loops, Bol-loops, Bruck-loops and the homogeneous loops of Kik-kawa became clear. The smallest examples of proper K-loops possess 8 elements; there are exactly 3 non-isomorphic of these. At last it is shown that one gets quite naturally a Frobenius-group as a quasidirect product of a K-loop (L,⊕) and a group D of automorphisms of (L,⊕) if D is fixed point free except from 0.     

Functionalization and further crosslinking of the nicalon polycarbosilane based on its metalation with the n-butyllithium—postassium t-butoxide reagent

Reaction of the Nicalon polycarbosilane with the n-BuLi/Me₃COK reagent resulted in metalation of approximately one CH₂ group in four. Reaction of the metalated polymer with Me₂ (CH₂ = CH)SiCl gave a Me₂(CH₂ = CH)Si-substitued Nicalon polycarbosilane. The polymer was heated with different amounts of the [(MeSiH)_～0.8(MeSi)_～0.2]_n polysilane in the presence of azobisisobutyronitrile in refluxing benezene. Hydrosilylation by the Si? H-containing polysilane of the CH₂?CH groups of the Me₂(CH₂?CH) Si-substituted Nicalon polycarbosilane gave a new hybrid polymer (when appropriate quantities of reactant polymers were used) whose pyrolyis in a stream of argon to 1000°C left a ceramic residue in 77% yield whose elemental analysis indicated a nominal composition of 91% by weight SiC and 9% C.     

A Maxmin Principle for Nonlinear Eigenvalue Problems with Application to a Rational Spectral Problem in Fluid-Solid Vibration

In this paper we prove a maxmin principle for nonlinear nonoverdamped eigenvalue problems corresponding to the characterization of Courant, Fischer and Weyl for linear eigenproblems. We apply it to locate eigenvalues of a rational spectral problem in fluid-solid interaction.     

Characterization of a class of triangle-free graphs with a certain adjacency property

Let m and n be nonnegative integers. Denote by P(m,n) the set of all triangle-free graphs G such that for any independent m-subset M and any n-subset N of V(G) with M ∩ N = Ø, there exists a unique vertex of G that is adjacent to each vertex in M and nonadjacent to any vertex in N. We prove that if m ? 2 and n ? 1, then P(m,n) = Ø whenever m ? n, and P(m,n) = {K_m,n+1} whenever m > n. We also have P(1,1) = {C₅} and P(1,n) = Ø for n ? 2. In the degenerate cases, the class P(0,n) is completely determined, whereas the class P(m,0), which is most interesting, being rich in graphs, is partially determined.     

Bestimmung von Cobalt in Blut mit Hilfe der elektrothermalen Atomabsorptionsspektrometrie

Zusammenfassung Es wird ein analytisch zuverlässiges atomabsorptionsspektrometrisches Direktverfahren zur Bestimmung der Cobaltkonzentration in Vollblut beschrieben. Durch die Anwendung eines dreistufigen Mineralisierungsprogramms und durch eine achtfache Verdünnung des Blutes gelingt es, die Veraschung und Verflüchtigung der organischen Bestandteile kontrolliert ablaufen zu lassen und Störeinflüsse der biologischen Matrix auf das Endergebnis zu eliminieren. Bei einer Nachweisgrenze von 2 g/l erlaubt diese Methode die Bestimmung erhöhter Cobaltspiegel in Blut, wie sie z. B. infolge beruflicher Belastungen auftreten. Die unter Wiederholungsbedingungen in der Serie und von Tag zu Tag ermittelte Unpräzision der Methode liegt zwischen 1 und 4% bzw. bei 6%. Die Richtigkeit des Verfahrens wurde sowohl durch Wiederfindungsversuche wie insbesondere durch Vergleich mit einem unabhängigen polarographischen Verfahren überprüft. An Blutproben beruflich Cobalt-exponierter Personen konnte gezeigt werden, daß das atomabsorptionsspektrometrische und das polarographische Verfahren zu Ergebnissen führen, die innerhalb der Fehlergrenzen als identisch anzusehen sind.

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Determination of cobalt in blood by electrothermal atomic absorption

Summary A reliable atomic absorption method for the direct determination of cobalt in blood is described. By means of a three-step mineralization programme and an eightfold dissolution of the blood it permits the mineralization and volatilization of the organic components under controlled conditions and the elimination of interference factors. A detection limit of 2 g/l allows the determination of elevated cobalt levels in blood which perhaps are caused by occupational exposure. In-series and between-day imprecision of the method were between 1 and 4% or 6%, respectively. The accuracy of the method was tested by recovery experiments and by comparison with an independent polarographic method. With the aid of blood samples of occupationally exposed persons it could be shown that the atomic absorption as well as the polarographic method lead to results being within the range of the methods imprecision.

     

Interlayer exchange coupling: an in situ investigation via ferromagnetic resonance

A new absolute way to deduce the interlayer exchange coupling via in situ ferromagnetic resonance measurements in Cu/Ni/Cu/Ni/Cu(0 0 1) films is presented. The signal of the first magnetic layer before and after the deposition of the second one is compared and the exchange coupling is extracted from the shift of the resonance position in the coupled system with respect to the Cu/Ni bilayer.