Stereochemie der Bildung und Spaltung der (Co?C)-Bindung an einem Vitamin-B12-Modell 3. (vorläufige) Mitteilung

Stereochemical Course of the Formation and Cleavage of the Co? C Bond in a Vitamin B₁₂ Modal The electrosynthesis and properties of a chiral cobalt alkyl complex 4 are described. The reductive cleavage of the Co–C bond occurs with retention of configuration at the C-atom.     

Making doughnuts of Cohen reals

For a ? b ? ω with b\ a infinite, the set D = {x ∈ [ω]^ω : a ? x ? b} is called a doughnut. A set S ? [ω]^ω has the doughnut property ?? if it contains or is disjoint from a doughnut. It is known that not every set S ? [ω]^ω has the doughnut property, but S has the doughnut property if it has the Baire property ?? or the Ramsey property ?. In this paper it is shown that a finite support iteration of length ω₁ of Cohen forcing, starting from L , yields a model for CH + (??) + (??) + (?).     

H-spectroscopic imaging using a modified Dixon method

Inhomogeneities of the static magnetic field and the different susceptibilities of the various types of tissue are a serious problem for all imaging methods of spectral separation of fat and water. In the Dixon method this problem is solved by using the absolute values of the image signals for the separation. In image regions where the fat signal is greater than the water signal, however, this results in an incorrect assignment of the computed solutions. A modified Dixon method was developed to easily carry out the spectral separation completely over the entire image by interactively building up a phase correction matrix after the data acquisition. The spectral delineation of the fat tissue finds an interesting application in the treatment planning with fast neutrons in accounting for the increase in dose.     

Scintillation properties of ZnWO4

Scintillation properties of ZnWO₄, bismuth doped ZnWO₄ and antimon doped ZnWO₄ were studied. Decay time, light yield and their temperature dependence are reported.