Zur Bestimmung kleiner Mengen von Niob mit 4-(2-Pyridylazo)-resorcin und von Zirkonium mit Brenzcatechinviolett in Stahl

Zusammenfassung Zur Bestimmung von Niob unter 0,06% und Zirkonium unter 0,1% in unlegiertem Stahl wird die Hauptmenge Eisen mit Methylisobutylketon aus 7 N HCl-Lösung abgetrennt. Niob wird bei pH 5,8 durch Komplexbildung mit 4-(2-Pyridylazo)-resorcin und Zirkonium bei pH 5,2 mit Brenzcatechinviolett bestimmt. Die Störungen durch andere Ionen werden durch Zugabe von ÄDTE verhindert und bei der Zirkoniumbestimmung teilweise durch Entfärben des gebildeten Komplexes mit Fluorwasserstoffsäure umgangen. Die erzielte Genauigkeit und der erforderliche Zeitbedarf sind in den Tabellen angegeben.

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Summary For the determination of niobium below 0.06% and of zirconium below 0.1% in plain carbon steels most of the iron is extracted by means of MIBK from 7 N HCl solution. Niobium is determined at pH 5.8 with 4-(2-pyridylazo)-resorcinol and zirkonium at pH 5.2 with pyrocatechol violet by the formation of complexes. Interferences from other ions are prevented by the addition of EDTA and in the case of zirconium farther avoided by bleaching the complex with hydrofluoric acid. The accuracy obtained and the time required are reported in the tables.

     

The Doss Trick on Symmetric Spaces

The Doss trick is employed to find solutions of Schrüdinger equations on symmetric spaces of compact type. The potentials and initial conditions are taken from an algebra of functions which admit an holomorphic extension to the complexification of the considered symmetric spaces.     

A Two Dimensional Fermi Liquid. Part 2: Convergence

Using results established in other papers in our series, we prove the existence of the infinite volume, temperature zero, thermodynamic Greens functions of a two dimensional, weakly coupled fermion gas with an asymmetric Fermi curve and short range interactions. This is done by showing that our sequence of renormalization group maps converges.Research supported in part by the Natural Sciences and Engineering Research Council of Canada and the Forschunginstitut für Mathematik, ETH Zürich.     

Axiomatizing the Harsanyi solution,the symmetric egalitarian solution and the consistent solution for NTU-games

The validity of the axiomatization of the Harsanyi solution for NTU-games by Hart (1985) is shown to depend on the regularity conditions imposed on games. Following this observation, we propose two related axiomatic characterizations, one of the symmetric egalitarian solution (Kalai and Samet, 1985) and one of the consistent solution (Maschler and Owen, 1992). The three axiomatic results are studied, evaluated and compared in detail.Revised October 2004We thank an anonymous referee and an associate editor for their helpful comments. Geoffroy de Clippel also thanks Professors Sergiu Hart, Jean-François Mertens and Enrico Minelli. Horst Zank thanks the Dutch Science Foundation NWO and the British Council for support under the UK-Netherlands Partnership Programme in Science (PPS 706). The usual disclaimer applies.     

Projective spaces with Cayley-Klein metrics

Projective metrics were first introduced by A. Cayley and F. Klein who constructed analytical models over the field of complex numbers. The aim of this paper is to give for the first time a purely synthetic definition of all projective spaces with Cayley-Klein metrics and to develop the synthetic foundation of projective-metric geometry to a level of generality including metrics over arbitrary fields of characteristic 2.