Über die Einwirkung von Bleitetraacetat auf Phenole VI

Zusammenfassung Es wird ein vereinfachtes Verfahren zur Oxydation von Phenolen mit Bleitetraacetat angegeben, sowie die Isolierung von 2,5-Dimethyl-o-chinolacetat, 2-Methyl-5-phenyl-o-chinolacetat, 3,4,5-Triphenyl-p-chinolacetat, ferner die Bildung von Diacetaten des 2-Hydroxy-o-chinols und 5-Methyl-2-hydroxy-o-chinols durch Bleitetraacetat-Oxydation der entsprechenden Phenole beschrieben. Unter den Produkten der Oxydation des o-Kresols wurde das Diacetat des 6-Methyl-2-hydroxy-o-chinols sowie ein Diphenylabkömmling gefunden. Die Theorie der Bildung dieser Stoffe wird durch einen radikalischen Mechanismus formuliert.     

Über die Photodimerisierung von Furocumarinen und das Sphondylin

Zusammenfassung Es wurde das Verhalten einiger Furocumarine bei der Belichtung untersucht, um festzustellen, in welchem Maße die Fähigkeit, Photodimerisate zu bilden, von der Konstitution abhängig ist. Wir konnten keinen einfachen Zusammenhang auffinden.Das bisher als Reinstoff betrachtete Furocumarin Sphondylin wurde als ein Gemisch von Sphondin und Bergapten erkannt.Mit 2 AbbildungenHerrn Prof. Dr.Emil Abel in aufrichtiger Verbundenheit zum 80. Geburtstag gewidmet.     

NMR signal averaging in 62T pulsed fields

Nuclear Magnetic Resonance (NMR) experiments in pulsed high magnetic fields up to 62T at the Dresden High Magnetic Field Laboratory (Hochfeld-Magnetlabor Dresden) are reported. The time dependence of the magnetic field is investigated by observing various free induction decays (FIDs) in the vicinity of the maximum of the field pulse. By analyzing each FID's phase and its evolution with time the magnetic field's time dependence can be determined with high precision. Assuming a quadratic or cubic dependence on time near the field maximum its confidence is found to be better than ± 0.03ppm at low fields and ± 0.8ppm near 62T. In turn, the thus obtained time dependence of the field can be used to demodulate and phase-correct all FIDs so that they appear phase-locked to each other. As a consequence signal averaging is possible. The increase in signal-to-noise ratio is found to be close to that expected theoretically. This shows that the intrinsic time dependence of the pulsed fields can be removed so that the NMR signals appear to be taken at rather stable static field. This opens up the possibility of performing precise shift measurements and signal averaging also of unknown, weak signals if a reference signal is measured during the same field pulse with a double-resonance probe.     

Dynamics and thermodynamics of the low-temperature strongly interacting Bose gas

We measure the zero-temperature equation of state of a homogeneous Bose gas of (7)Li atoms by analyzing the in situ density distributions of trapped samples. For increasing repulsive interactions our data show a clear departure from mean-field theory and provide a quantitative test of the many-body corrections first predicted in 1957 by Lee, Huang, and Yang [Phys. Rev. 106, 1135 (1957).]. We further probe the dynamic response of the Bose gas to a varying interaction strength and compare it to simple theoretical models. We deduce a lower bound for the value of the universal constant ξ > 0.44(8) that would characterize the universal Bose gas at the unitary limit.     

Über eine Umlagerung in der Flavonreihe

Ohne Zusammenfassung     

A new approach to the quantum KdV

We present a new formulation for the quantum evolution equation of KdV type. It is shown explicitly that a generalization of the usual recursion operator is possible, even when we follow the rules of quantization and assume that the nonlinear field variables do not commute. We also demonstrate that this recursion operator generates in a recursive way an infinite number of Hamiltonians commuting with each other, thus giving a basis for the complete integrability of the quantum mechanical evolution of the field. It is discovered that the reason why the recursion operator for the quantum KdV was not discovered earlier lies in the fact that this recursion operator is more closely connected to the general theory of the KP than to that of the KdV.     

Filter automata admitting oscillating carrier waves

Group-valued cellular automata with soliton behavior are considered and a Fast Rule theorem is proved. This new class of automata generalizes those recently introduced by Fokas, Papadopoulou and Saridakis [1].