Über die Wahrscheinlichkeit dafür,daß der Konvergenzkreis einer Potenzreihe ihre natürliche Grenze ist

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A family of rotating disks as sources of the Kerr metric

A method of constructing a family of regular rotating disks as sources of the Kerr metric is discussed. The algebraic type of the energy-momentum tensor is analyzed, and it is found that none of the disks satisfies the dominant energy condition and, in some cases, even the weak energy condition is violated. Therefore, if the constructed family includes the totality of sources for the Kerr metric with a disk-like topology, then any physically satisfactory source will not have a disk structure.     

Hyperfine and Magnetic Characterization of Fe Particles Hosted in Carbon Nanocapsules

Iron particles encaged in carbon nanocapsules have been produced by the Krätschmer–Huffmann carbon-arc discharge method. Soot, collarette and cathode samples have been characterized by Mössbauer spectroscopy and magnetic measurements in the temperature range 4.2–300 K. Different iron phases and iron-carbon solid solutions have been detected in our samples. The Einstein model has been used to evaluate the coupling constant between the particles and their environment, yielding values of the order 1–10 N/m. Irreversibilities observed at ZFC and FC curves for soot samples would suggest the presence of superparamagnetism only if the particles presented a blocking temperature above 300 K.     

Unter dem Titel: Chemische Pr?paratenkunde

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