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  • 1
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary An emission-spectrometric method was applied in the presence of CsCl-graphite buffer for the quantitative determination of traces of rare earth elements in yttrium oxide. The buffer causes an increase of the evaporation rate of the sample and of the emission intensity. The temperature in the arc plasma is decreased, and the atoms and ions of rare earths distribute uniformly along the axis of the discharge gap. The CsCl-graphite buffer enhances the sensitivity and the precision of the analytical elements to a larger extent than other buffers and permits the determination of microquantities of 10 impurity elements within limits of detection from 1 to 20 ppm in high-purity yttrium oxide. The coefficients of variation are less than 20%.
    Notes: Zusammenfassung Durch den Zusatz des CsCl-Graphitpuffers werden Verdampfungsgeschwindigkeit und Emissionsintensität erhöht, die Temperatur im Bogenplasma herabgesetzt und eine gleichmäßige Verteilung der Atome und Ionen längs der Entladungsstrecke bewirkt. Empfindlichkeit und Genauigkeit der Bestimmung sind besser als bei Verwendung anderer Puffer. 10 Verunreinigungselemente können mit Nachweisgrenzen von 1–20 ppm in hochreinem Yttriumoxid bestimmt werden. Die Variationskoeffizienten liegen unter 20%.
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  • 2
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A direct-reading emission-spectrometric method was applied in the presence of methanol for the quantitative determination of traces of rare earths and diverse other elements in rare-earth compounds by the rotating electrode. Addition of alcohols with lower boiling points than water causes an increase of the rate of vaporization of the sample solution and of the emission intensity. Methanol enhances the emission intensity to a larger extent than other alcohols and permits the determination of microquantities of the elements within limits of detection from 1 to 37 ppm in high-purity rare-earth compounds. The intensity ratio of the ionic line to the atomic line increases in the presence of more than 60% methanol, indicating the elevation of plasma temperature.
    Notes: Zusammenfassung Durch Zusatz von Alkoholen mit niedrigeren Siedepunkten als Wasser wird die Verdampfungsgeschwindigkeit der Lösung erhöht und die Linienintensität gesteigert. Methanol zeigt diese Wirkung in größerem Maße als andere Alkohole und ermöglicht die Bestimmung von Spuren Seltener Erden und anderer Elemente in Selten-Erd-Verbindungen hoher Reinheit mit Nachweisgrenzen von 1–37 ppm. Bei Gegenwart von mehr als 60% Methanol wird das Intensitätsverhältnis der Ionen- zur Atomlinie vergrößert, was auf eine Erhöhung der Plasmatemperatur zurückgeführt wird.
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  • 3
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A dc arc excitation method in a controlled atmosphere was applied in the presence of CsCl-graphite (1∶9) buffer for the quantitative determination of traces of rare earth elements in europium oxide. The intensities of the cyanogen band spectra and the background could be reduced by the use of argon-oxygen (4∶1) mixed gas atmosphere and it was possible to obtain higher sensitivity than in the excitation in air. Addition of CsCl-graphite buffer causes an increase of the evaporation rate of the sample and of the number of atoms in the arc plasma, and the atoms and ions of rare earths distribute uniformly along the axis of the discharge gap. The buffer enhances the sensitivity and reproducibility and permits the determination of microquantities of 10 impurity elements within limits of detection from 3 to 11 ppm in high-purity europium oxide. The coefficients of variation are less than 13%.
    Notes: Zusammenfassung Die Anregung erfolgt im Gleichstrombogen in kontrollierter AtmosphÄre (Argon/Sauerstoff, 4∶1) in Gegenwart eines CsCl-Graphit (1∶9)-Puffers. Durch die Verwendung von Argon/Sauerstoff konnte die IntensitÄt des Untergrundes und der Cyanbanden erheblich reduziert und eine grö\ere Empfindlichkeit erreicht werden als bei der Anregung in Luft. Durch den Puffer wird die Verdampfungsgeschwindigkeit erhöht, die Anzahl der Atome im Bogenplasma vergrö\ert und eine gleichmÄ\ige Verteilung der Atome und Ionen lÄngs der Bogenachse erzielt. Empfindlichkeit und Reproduzierbarkeit werden verbessert. Spurenverunreinigungen von 10 Elementen können in hochreinem Europiumoxid bestimmt werden. Die Nachweisgrenzen liegen zwischen 3 und 11 ppm; der Variationskoeffizient ist 〈 13%.
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  • 4
    ISSN: 1615-6102
    Keywords: Chemotaxis ; Information processing ; Oscillation ; Physarum polycephalum ; Thermal image camera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The spatial and temporal pattern of oscillating temperatures on the cell surface of a plasmodial strand ofPhysarum polycephalum was measured with a sensitive thermal image camera. The longitudinal tension of the strand was studied simultaneously. In the absence of chemical stimulation, the phases of the temperature oscillation observed at various portions of the strand were entrained with almost coincidental phase. The temperature and tension oscillation were synchronized, although the phase difference between them was occasionally changed. With local chemical stimulation, the phase of the temperature oscillation advanced in the portion to which the plasmodium would be induced to migrate. The phases between temperature and tension oscillations then became constant. The mechanism by which the plasmodium processes local information of chemical stimulus to global information for the migration is discussed.
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  • 5
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 6 Ill.
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  • 6
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Cold-drawn copper wires were made by cold-drawing after hot-rolling tough pitch copper rods which had been pre-heated at 673–973 K. The wires were annealed at 293–673 K to study their annealing properties. The effects of pre-heating the hot-rolled tough pitch copper rods, including lead, on the recrystallization behaviour of the cold-drawn copper wires were investigated by tensile tests, electrical resistivity measurements and structural observations. The half-softening temperature of annealed cold-drawn copper wires decreased when the hot-rolled copper rods were pre-heated at 873 K before cold-drawing. This behaviour was attributed to separation of lead dissolved in the copper matrix which is known to lower the half-softening temperature.
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  • 7
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 8
    ISSN: 1615-6102
    Keywords: Physarum polycephalum ; Spatio-temporal pattern of Ca2+ ; concentration ; Information processing ; Intracellular Ca2+ ; Chemotaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of a spatio-temporal pattern of Ca2+ concentration by a plasmodium ofPhysarum polycephalum during chemotaxis was studied using fura-2. Whenever the cell displayed coordinated migration in one direction as a whole body, a spatiotemporal pattern was established with a characteristic feature along the longitudinal axis. Calcium concentration oscillated with a period of a few minutes within the cell; the mean concentration at the front was higher than that at the rear. When the cell was given an attractant only at the rear end, the mean concentration rose at the site of application with an immediate increase in the frequency of oscillation. First, the change of the frequency is propagated toward the other end and then the mean level of the Ca2+ concentration at the non-stimulated site decreases. As a result, the Ca2+ gradient is reversed along the cell, which then begins to migrate in a coordinated manner in the reverse direction. This study showed that the spatiotemporal pattern of Ca2+ concentration is closely related to information processing for coordinated migration in chemotaxis. The role of the pattern in that process is discussed.
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  • 9
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The muon spin resonance method was applied to measure theμ + polarization corresponding to the muon state in diamagnetic compounds in CS2, water and benzene under 3 kG decoupling field. We observed almost the same diamagnetic polarizations under decoupling field, compared to those at zero decoupling field observed under the transverse field, except in CS2 The results indicate that most of the so called “missing fraction” is not associated with diamagnetic species produced as a final state of rapid chemical reactions of muonium in these samples.
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  • 10
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Evidence for the emission of slow muonium atoms from a 3.0-nm-thick SiO2 layer covered on an n-type Si is reported. Also, upon applying an rf-resonance technique at the muon frequency, a time-differential observation of a delayed state-change from muonium to diamagnetic muon at room temperature was observed. Combining results obtained by use of longitudinal field decoupling and transverse spin rotation methods, the conversion rate was estimated to be 5 to 10 μs−1. Both of the above results, namely the observation of the emission and state-change of muonium, suggest a process in which μ+ initially captures an electron from Si, then quickly converts to μ+ again during thermal diffusion in the Si towards the SiO2 layer. Within the oxide layer, muonium is again formed and subsequently is emitted from the SiO2 surface.
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