5′‐O‐(4,4′‐Dimethoxytrityl)thymidine was attached to a pentaerythrityl‐derived core, and the resulting tetravalent nucleoside cluster and the next dendritic generations served as a soluble support for the synthesis of short oligo‐2′‐deoxyribonucleotides in solution. Couplings using a small excess (1.5 equiv. per 5′‐OH group) of the standard phosphoramidite building blocks proved efficient, and the products could be purified by quantitative precipitation from methanol. Ammonolysis released nearly homogeneous oligonucleotides (CCT, GCT, ACT, and AGCCT) in high yields.

Silicon wafers especially prepared to meet a customer's needs in the production of semiconductor memory circuits are studied with synchrotron section topography. A well-defined uniform denuded zone below the surface with a width of 12 to 24 ~tm is observed. The concentration and the size of the oxygen-related defects in the bulk are independent of the location along the crystal ingot, from which the wafer originates, and of that along the wafer diameter.