Abstract: Leakage from the manifold of a manifold type multi-channel dispenser, aspirator, or washer may be diminished by employing siphon shaped pipettes and backsipping liquid from the long leg of such siphon shaped pipettes after each use of the device. The siphon shaped pipettes may be attached to the top-most part of the manifold so as to facilitate the purging of bubbles therefrom.

Abstract: Novel oligonucleotides formed from .alpha.-D-arabinofuranosyl nucleoside monomers, including oligonucleotides in which one or more of the monomer units is functionalized, are disclosed herein, as well as functionalized monomeric .alpha.-D-arabinofuranosyl nucleosides and nucleotides. A generic formula for the oligomers is: ##STR1## in which B is a nucleotide base which will vary from one monomeric unit to the next in a preselected oligonucleotide sequence; R is phosphate, phsophorothioate, phosphoramidate, or alkanephosphonate; t is 1 for functionalized monomeric units and zero for the others; W is a chemical linker arm; A is a functional group; and n is the number of monomeric units in the oligomer. The oligomers are useful for diagnostic and chemotherapeutic uses. A novel reaction is also disclosed, in which an .alpha.-D-arabinofuranosyl nucleoside with exposed hydroxyls at the 2'- and 3'-positions is selectively protected at the 2'-position in a single reaction.