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  • Springer  (47)
  • American Institute of Physics (AIP)  (3)
  • Inter-Research
  • 2015-2019  (3)
  • 1995-1999  (32)
  • 1980-1984  (16)
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  • 1
    Electronic Resource
    Electronic Resource
    Thermal vacancy formation and positron–vacancy interaction in Ti3Al at high temperatures (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 724-728 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In order to study the formation of thermal vacancies in the Ti–Al alloy system, high-temperature positron lifetime measurements together with a modeling of defect formation in the framework of nearest-neighbor pair bonds were performed for α2Ti3Al and compared to recent results on γTiAl [U. Brossmann, R. Würschum, K. Badura, and H.-E. Schaefer, Phys. Rev. B 49, 6457 (1994)]. Substantial increases of the positron lifetime τ were observed for Ti65.6Al34.4 and Ti77.1Al22.9 in the temperature range T(approximately-greater-than)1200 K where thermal vacancy concentrations above the detection limit of positron annihilation are expected from the model calculations for the α2 phase. Within the high-temperature increase of the positron lifetime in the α2 and the β phase single-component positron lifetime spectra were observed. This behavior is in contrast to the two-component spectra observed conventionally at intermediate positron trapping rates and is attributed to a fast detrapping and retrapping of positrons at vacancies due to a low positron–vacancy binding energy. For this case, a vacancy formation enthalpy of HFV=(1.55±0.2) eV in α2Ti65.6Al34.4 and HFV=(1.8±0.2) eV in βTi77.1Al22.9 can be derived. These results are discussed in the context of recent 44Ti tracer diffusion studies. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362880
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetism and microstructure of nanocrystalline nickel : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5143-5145 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In order to study the influence of the nanocrystalline microstructure on the magnetic properties of pure nanocrystalline metals, in situ magnetic measurements of high-purity nanocrystalline nickel, prepared by a gas-condensation technique with subsequent compaction at various pressures have been performed. The approach to ferromagnetic saturation indicates free volumes in the nanocrystalline system of the size of individual missing crystallites as well as internal stresses. While the saturation polarization of the nanocrystalline Ni samples appears to be unchanged compared to coarse-grained Ni the coercive field and magnetic domains are strongly influenced by the nanocrystalline structure. The shape of the domains with sizes of 10–200 μm much larger than the crystallite size depends on the annealing state of the specimen. The initial coercive field increases with the compaction pressure during preparation. Upon annealing it further increases to a maximum value at Ta=500 °C and decreases at higher annealing temperatures. Additionally, the effect of oxygen located in the grain boundaries has been studied. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361535
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  • 3
    Electronic Resource
    Electronic Resource
    Schriftenschau (1999)
    Springer
    Journal of ornithology 140 (1999), S. 207-210 
    Details
    ISSN: 1439-0361
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01653600
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  • 4
    Electronic Resource
    Electronic Resource
    Measurement of the asymmetry in the emission of Röntgenbremsstrahlung produced by transversely polarized electrons (1982)
    Springer
    The European physical journal 305 (1982), S. 213-215 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The asymmetric emission of Röntgenbremsstrahlung produced in the scattering of transversely polarized electrons by Au-atoms was measured at an electron energy ofE =mc 2/4 for photon emission anglesθ=60°, 100°, 145° and compared to calculations of this process based on a partial waves method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01417436
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  • 5
    Electronic Resource
    Electronic Resource
    Substituierte 2-Alkoxy-5-amino- und-2,5-diamino-imidazole aus Oxazol-2-yliden-cyanamiden (1996)
    Springer
    Monatshefte für Chemie 127 (1996), S. 313-318 
    Details
    ISSN: 1434-4475
    Keywords: (2-Alkoxy-5-amino-imidazol-4-yl)-ketones ; N-Cyano-S-methyl-isothioureases ; (2.5-Di-amino-imidazol-4-yl)-ketones ; α-Halogenketones ; Oxazol-2-yliden-cyanamides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary N-Cyano-S-methyl-isothio-ureases (1) react with α-halogen ketones (2) by ring closure yielding the (3H-oxazol-2-yliden)-cyanamides3. by ring transformation, 2-Alkoxy-5-amino-1-phenyl-3H-imidazol-4-yl)-ketones (4) are formed. Primary and secondary amines react with3 to give 2-N-alkylated (2,5-Diamino-1-phenyl-3H-imidazol-4-yl)-ketones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00813797
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  • 6
    Electronic Resource
    Electronic Resource
    New syntheses of 2,4-diaminopyrroles and aminopyrrolinones (1997)
    Springer
    Monatshefte für Chemie 128 (1997), S. 933-943 
    Details
    ISSN: 1434-4475
    Keywords: Thorpe-Ziegler cyclization ; (Oxazolin-2-yliden)malononitrile ; 2,4-Diamino-pyrrole ; 2-Amino-4-oxo-pyrrol-3-carbonitrile ; 4-Amino-2-oxo-pyrrol-3-carbonitrile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Oxazolin-2-yliden-malononitrile3a–d. die aus Thioketenaminalen und α-Halogenketonen erhalten wurden, reagieren mit primären und sekundären Aminen zu den 2,4-Diaminopyrrolen5a–h. Mercaptobenzol als nukleophiles Reagens liefert 4-Amino-2-phenylthiopyrrol (5j). Analog wurden Cyan-(3,5-diphenyl-3H-oxazol-2-yliden)-essigsäuremethylester als Zwischenprodukte für die Synthese der 2-Amino-4-oxo-pyrroline10a–d hergestellt. Die isomeren 4-Amino-2-oxo-pyrroline13a–d können aus den 4-Amino-2-methoxy-pyrrolen11a,b erhalten werden, was als Nachweis für die Position der Substituenten dient. Die Verbindungen wurden1H- und13C NMR-spektroskopisch untersucht.
    Notes: Summary Oxazolin-2-ylidene-malononitriles3a–d, obtainable from thioketenaminals and α-halogen-ketones, react with primary and secondary amines to afford 2,4-diamino-pyrroles5a–h. Mercaptobenzen as nucleophilic agent gives the 4-amino-2-phenylthio-pyrrole5j. Analogously, cyano-(3,5-diphenyl-3H-oxazol-2-ylidene)-acetic acid methyl esters were prepared as intermediates for the synthesis of 2-amino-4-oxo-pyrrolines10a–d. The isomeric 4-amino-2-oxo-pyrrolines13a–d can be obtained from 4-amino-2-methoxy-pyrroles, which serves as proof for the position of substituents. The structures were investigated by1H and13C NMR spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807103
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  • 7
    Electronic Resource
    Electronic Resource
    Synthese neuartig substituierter Pyridazin-6(1H)-one (1995)
    Springer
    Monatshefte für Chemie 126 (1995), S. 341-347 
    Details
    ISSN: 1434-4475
    Keywords: Chloroacetic acid chloride ; Phenylhydrazono acetamides ; Pyridines ; Pyridazin-5-ylpyridinium chlorides ; 4,5-Diamino-pyridazin-6(1H)-ones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Arylhydrazono acetamides1 react with chloroacetic acid chloride to give N-chloroacetyl derivatives2. Subsequent reaction with pyridines followed by ring closure yield 1-(4-amino-6-oxo-pyridazin-5-yl)-pyridinium chlorides3. Analogously, 1-(6-oxo-pyridazin-5-yl)-pyridinium chloride (5) and 6-oxo-5-pyridinio-pyridazin-4-olate (4) are formed from phenylhydrazono derivatives and pyridine. Treatment of3 and4 with hydrazinium hydrate gives 4,5-diamino-6-oxo-pyridazin-3-carbohydrazides6 and 5-amino-4-hydroxy-pyridazin-6(1H)-one (8). An analogous ring cleavage of3e and5 gives rise to 4,5-diamino- and 5-amino-pyridazin-6(1H)-ones7. On treatment of the pyridinium salts3 with caustic soda in water, nucleophilic addition of the amino group to the pyridinium ring takes place and stable dehydrated products9 are isolated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00816103
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  • 8
    Electronic Resource
    Electronic Resource
    Syntheses with pyridinium and sulfonium salts of acylated β-enaminonitriles (1995)
    Springer
    Monatshefte für Chemie 126 (1995), S. 711-723 
    Details
    ISSN: 1434-4475
    Keywords: Malononitrile ; Benzoles ; Pyridines ; Thiophenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Pyridinium- und Sulfoniumsalze2a–e, die aus 3-Amino-2-(α-halo-acetyl)-crotonsäurenitril und 3-Amino-2-(α-halo-acetyl)-zimtsäurenitril hergestellt werden können, reagieren mit Malonsäuredinitril in Gegenwart einer Base zu 3-Amino-2-pyridinio-phenolaten3a,b und 3-Amino-2-sulfonio-phenolaten3c–e. In Analogie wurden 3-Amino-2-(diethyloxyphosphoryl)-phenol5a und 3-Amino-2-(p-tolyl-sulfonyl)-phenol5b erhalten. 2,3-Diamino-phenole6a,b werden aus den Pyridiniumsalzen3a,b gebildet. Das Verhalten der Pyridiniumsalze2a,b gegenüber Heterokumulenen ist untersucht worden. Cyanamid führt zum (2-Amino-4-hydroxy-pyrid-3-yl)-pyridiniumsalz8c. Phenylisothiocyanat liefert die 3-Pyridinio-2-thioxo-pyridin-4-olate9a,b. In Abhängigkeit vom Substituenten in der Position 6 entsteht bei der Reaktion mit Schwefelkohlenstoff ein 3-Pyridinio-2-thioxo-pyridin-4-olat10 oder ein 3-Pyridinio-2-thioxo-thiopyran-4-olat11. Phenylisocyanat reagiert zum Pyrimidin-2,4-dion12 unter Verlust von N-Methyl-pyridiniumchlorid. S-Methylierung von9a und Spaltung des Pyridiniumringes ergibt das 3-Amino-2-methylthio-pyrid-4-on14. Die Verbindungen wurden1H- und13C-NMR-spektroskopisch untersucht.
    Notes: Summary Pyridinium and sulfonium salts2a–e which can be prepared from 3-amino-2-(α-haloacetyl)-crotonitriles and 3-amino-2-(α-halo-acetyl)-3-phenyl-acrylonitriles react with malononitrile in the presence of a base to 3-amino-2-pyridinio-phenolates3a,b and 3-amino-2-sulfonio-phenolates3c–e. In an analogous way, 3-amino-2-(diethyloxyphosphoryl)-phenol5a and 3-amino-2-(p-tolyl-sulfonyl)-phenol5b have been prepared. 2,3-Diamino-phenoles6a,b are formed from the pyridinium salts3a,b. The behaviour of the pyridinium salts2a,b towards heterocumulenes has been investigated. Cyanamide leads to the (2-amino-4-hydroxy-pyrid-3-yl)-pyridinium salt8c. Phenylisothiocyanate gives the 3-pyridinio-2-thioxo-pyridin-4-olates9a,b. Carbon disulfide gives rise to 3-pyridinio-2-thioxo-pyridin-4-olate10 or 3-pyridinio-2-thioxo-thiopyran-4-olate11, depending on the substituent at the 6-position. Phenylisocyanate reacts to the pyrimidin-2,4-dione12 with loss of N-methyl-pyridinium chloride. S-methylation of9a and cleavage of the pyridine moiety yields the 3-amino-2-methylthio-pyrid-4-one14. The structures were investigated by1H and13C NMR spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807162
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  • 9
    Electronic Resource
    Electronic Resource
    Interpolation of spectra (1980)
    Springer
    Integral equations and operator theory 3 (1980), S. 463-469 
    Details
    ISSN: 1420-8989
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract By the M.Riesz Convexity Theorem, an operator T on the space of simple integrable functions into the measurable functions (on some measure space) which has continuous extensions to Lp(μ) and Lq(μ) , where 1 ⩽ p ⩽ q ⩽ ∞ , also has continuous exten — sions to all Lr (μ) , p ⩽ r ⩽ q . It is shown that, whenever σ(Tp) and σ(Tq) are o-dimensional (in particular, countable) then the spectra σ(Tr) (p ⩽ r ⩽ q) are pairwise identical. For q = ∞ , only w*-continuous extensions are considered. An example due to Dayanithy shows that the conclusion fails in general.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01701502
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  • 10
    Electronic Resource
    Electronic Resource
    Resonance Brillouin scattering from quantized exciton-polaritons in ultrathin epitaxial layers of ZnSe (1995)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 1753-1757 
    Details
    ISSN: 0392-6737
    Keywords: Brillouin and Rayleigh scattering ; Polaritons (including photon-phonon and photon-magnon interactions) ; Electron states in low-dimensional structures (including quantum wells, superlattices, layer structures and intercalation compounds) ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Resonant Brillouin scattering in ultrathin MBE-grown epitaxial layers of ZnSe with thicknesses from 50 to 200 nm is esployed to investigate the properties of the 1s exciton-polariton states. The effective masses are found different from that in bulk ZnSe caused by the energetic decoupling of heavy- and light-hole states due to strain. In the 50 nm sample the momentum selection rule is relaxed, leading to broad Brillouin lines that show fine structure due to the phonon quantization in these layers, whereby dilatation and flexural phonon modes are involved in the scattering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457275
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