Experimental study of the draw resonance in fiber spinning

An experimental fiber-spinning device has been built in order to study the draw-resonance phenomenon in nearly isothermal conditions. The influence of the output rate, of the take-up speed and of the spinning length was studied for four different polyesters. The experimental results are in accordance with non-isothermal and viscoelastic computations.     

On shortest cocycle covers of graphs

A cocycle (resp. cycle) cover of a graph G is a family C of cocycles (resp. cycles) of G such that each edge of G belongs to at least one member of C. The length of C is the sum of the cardinalities of its members. While it is known (see [5, 6]) that every bridgeless graph G = (V, E) has a cycle cover of length not greater than $\text{5}\text{3}\text{|E|}$, it is shown that there exists no α < 2 such that every loopless graph G = (V, E) has a cocycle cover with length not greater than α |E|. To do this, cocycle covers of minimal length are determined for the complete graphs, thus solving a problem stated at the end of [6].     

Septorine and N-methoxy septorine,substituted pyrazines from the fungus Septoria nodorum berk

On the basis of ¹H nmr correlations with synthetic analogs, structures $\text{1}$ and $\text{2}$ are proposed for septorine and N-methoxy septorine, two p-hydroxybenzoyl 1-isobutyl substituted pyrazines obtained from the fungus $\text{Septoria nodorum}$ Berk, a parasite of wheat.     

The synthesis and crystal structure of triphenylvinyltin

Triphenylvinyltin has been prepared by an improved method. It crystallizes in the Pbn2₁ space group; the crystal contains two non-equivalent molecules which have almost the same conformation. The latter are compared with the conformations in tetraphenyl-methane, -silane, -germane, -tin and -lead.     

On bornologicalC $$\overline V $$ (X) spaces

Archiv der Mathematik -     

Synthesis of (+) dictyopterene a constituent of marine brown algae and (+) dictyopterene C′ by chirality transfer of optically active allylic benzoate with palladium (O) catalyst.

The first enantioselective syntheses of (+) dictyopterene A $\text{1}$ and (+)dictyopterene C′ were reported. The key reaction was based on palladium promoted cyclisation of chiral allylic benzoate $\text{5}$ with transfer of chirality (anti attack of the palladium with respect to the leaving group) to give optically active vinylcyclopropane $\text{7}$ with (R) configuration which contains proper functionality for further elaboration into $\text{1}$ and $\text{3}$