Zur Geschichte der Bohr-Sommerfeldschen Quantentheorie

On the History of Bohr-Sommerfeld Quantum Theory In the present paper articles of N. Bohr, P. Ehrenfest, A. Sommerfeld, P. Epstein and K. Schwarzschild are reviewed with respect to the conceptual essentials in the history of the early quantum theory during the period from 1914 to 1918.     

Unser griechisches Erbe

Our Greek Inheritance It is shown that fundamental concepts of physics may be traced back to Greek Natural Philosophy, especially to Pythagoreism, Platonism, and to Demokrit's Atomism. At the end of the paper a brief glance is thrown on the relation between Aristotelism and physics.     

Optical activity of oriented molecules. comparison of the optical rotatory dispersion and the circular dichroism through the kramers-kronig transform

Circular dichroism and optical rotatory dispersion of anisotropic solutions of testosterone propionate in cholesteryl chloride/cholesteryl laurate have been measured with light propagating parallel to the optical axis of the uniaxial system. Comparison of both effects by the Kramers-Kronig relation excludes falsification by interference with linear birefringence and dichroism effects.     

New synthetic approach to yttrium hydroxoacetates, structural characterization, and use as a precursor for coated conductors

A novel synthetic approach is given for the preparation of a metal-organic lanthanide sol-gel precursor solution and its application for the production of coated conductors. Besides all other problems concerning the technical process itself, the key to a successful deposition of oxide layers is the choice of the precursor solution and the understanding of the mechanism of deposition. Moreover, the isolation and characterization of the species involved in the reaction is very important. Regarding the complex process occurring during the formation of the surface layer, it is obvious that the best choice should have a compound already containing the final composition of the layer. Two compounds of composition [Y(OAc)3(H2O)2]2 and [Y(OAc)3]2(H2O) were isolated from their precursor solution and characterized by X-ray structural analysis. A short outlook will give an insight into the possible bonding mechanisms of the surface layer. These experiments were made with the mixed metal-oxide system yttrium-stabilized zirconium oxide, which is widely used as a substrate for superconducting oxides. A study of the structure of hydrated yttrium acetates, by single-crystal X-ray diffraction, infrared spectra, and elemental analysis demonstrates that there are two separate structures for hydrated yttrium acetates, which play a role as an intermediate in the building of ceramic oxide layers for coated conductors.     

Twista-4,9-diene. Preliminary communication

A synthesis of twista-4,9-diene ( 17 ) from tricyclo[4.3.1.0^3,8]dec-4-en-10-one ( 2 ) is described.