Structural diversity of organic chemistry. A scaffold analysis of the CAS Registry.

By analyzing the scaffold content of the CAS Registry, we attempt to characterize in a comprehensive way the structural diversity of organic chemistry. The scaffold of a molecule is taken to be its framework, defined as all its ring systems and all the linkers that connect them. Framework data from more than 24 million organic compounds is analyzed.

Long-term study of virus contamination of surface water in the German Democratic Republic.

Between 1 January 1970 and 31 December 1979, a study of the concentration of viruses in surface water was carried out by 4 virological laboratories in different regions of the German Democratic Republic. All these laboratories used the same methods for virus detection.Altogether 1908 samples from 30 sampling points were evaluated.