Stress-induced magnetic easy axis in amorphous Fe40Ni40P14B6

In a ribbon of amorphous Fe₄₀Ni₄₀P₁₄B₆ (Metglas 2826) the iron spins tend to be parallel to the plane of the ribbon, but the distribution of spin directions within the plane is nearly random. When a uniaxial tensile stress is applied to the ribbon the spins become almost completely aligned parallel to the applied stress. The technique of Mössbauer polarimetry was used to detect and measure this effect.     

Discrete degenerate representations of non-compact unitary groups

Two degenerate principal series of irreducible unitary representations of an arbitrary non-compact unitary groupU(p,1) are derived. These series are determined by the eigenvalues of the first and second-order invariant operators, which are shown to possess a discrete spectrum. The explicit form of the corresponding harmonic functions is derived and the properties of the discrete representations are discussed in detail. Moreover, in the Appendix, we derive the properties of the corresponding degenerate representations of an arbitrary compactU(p) group.On leave of absence from Institute of Nuclear Research, Warsaw, Poland.On leave of absence from Institute of Physics of the Czechoslovak Academy of Sciences, Prague, Czechoslovakia.     

Microwave study of proximity effects in superconductivity

The microwave surface resistance of a thin layer of copper in close contact with the surface of bulk lead is investigated. It is found that the basic ideas about proximity effects in superconductivity developed in recent years are capable of explaining the observed behaviour very satisfactorily. Our data give evidence of a complex excitation spectrum in the copper, with low energy excitations above a true gap and a group of high energy excitations which is usually observed in tunneling experiments. The response to a magnetic field shows that scattering at the free copper surface is diffuse. This leads at low fields, where a Meissner shielding current flows at the copper surface, to a decrease of the depairing energy by a large amount of first order in the vector potentialA instead of only a small second order amount. This also explains an initial decrease of the absorption when a weak magnetic field is applied. For fields over a large range below the critical field of lead superconductivity is effectively suppressed in copper. The data also give information on the increase of the penetration depth in lead because of the coating with copper and on the effective electron-electron interaction in copper: $$\lambda \to 2\lambda _L and (NV)_{Cu} \cong 0.05.$$      

Zur Bestimmung des günstigsten Standortes einer Betriebsfiliale

Zusammenfassung Am Beispiel des Warenhausproblems wird auf der Basis der linearen Planungsrechnung und der Spieltheorie ein mathematisches Modell konstruiert, das allgemeineren Problemen der Energie- und Warenversorgung als Grundlage dienen kann. In einem ersten Teil werden die zur Rechnung notwendigen Formeln hergeleitet und Hinweise auf Änderungsmöglichkeiten gegeben. In einem zweiten Teil wird dann das Warenhausproblem mit vorgegebenen Zahlen durchgerechnet. Die Lösungen werden auf ihre wirtschaftliche Bedeutung hin untersucht.

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Summary On example of the warehouse problem a mathematical model will be constructed basing on the theory of linear programming and theory of games, which can be used basically for more general problems of energy- or ware-supply. In the first part the formulas necessary for programming will be written and possibilities for change will be given. In the second part the warehouse problem will be counted over with predetermined numbers. The results will be tested on its economical importance.

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Vorgel. v.: W. Knödel     

Möglichkeiten und Grenzen der Anwendung einer direkten Kombination Gaschromatograph—hochauflösendes Massenspektrometer bei der Untersuchung von in biologischen Materialien vorkommenden Steroiden

Zusammenfassung Die Kombination eines Gaschromatographen mit einem hochauflösenden Massenspektrometer kann bei der Untersuchung von Steroidgemischen, die aus biologischen Materialien isoliert wurden, rasche Information über sonst kaum nachweisbare Steroidmetaboliten liefern. Die Erfassungsgrenze liegt bei etwa1 .Freie Steroide zeigen strukturspezifischere Spektren als ihre Trimethylsilylderivate, so daß, wenn immer möglich, auf eine Silylierung zur gaschromatographischen Trennung verzichtet werden sollte. Ist wegen der Schwerflüchtigkeit der Verbindung eine Derivatbildung notwendig, so ist die Umwandlung von Hydroxysteroiden in entsprechende Ketosteroide in den meisten Fällen einer Trimethylsilylierung vorzuziehen.Umsetzungen können im Gemisch ausgeführt werden, so daß zumindest eine teilweise Strukturaufkläurung ohne Reinisolielierung der Probe mit Mengen von 10 bis 20 möglich ist.

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Possibilities and limitations of using a direct combination of gas chromatograph—high resolution mass spectrometer in the study of naturally occurring steroids

The combination of a gaschromatograph with a high resolution mass spectrometer may provide in the investigation of steroids, isolated from natural sources, fast information about otherwise barely detectable minor steroid metabolites. The limit of detection is about 1 .Free steroids show more structure specific spectra than their corresponding trimethylsilyl derivatives. Therefore the preparation of trimethylsilyl derivatives for the purpose of gaschromatographic separation should be avoided if possible. If low volatility necessitates the preparation of a derivative, in most cases the preparation of keto derivatives from hydroxysteroids should be preferred to the preparation of trimethylsilyl ethers.Reactions can be carried out with the mixture, so that-without preparation of pure samples-at least partial structure determinations are possible with 10–20 .

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Mit 14 Abbildungen

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Herrn Prof. Dr.F. Kuffner zum 65. Geburtstag gewidmet.