. . "This represents a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbons, or a R18CO??? group (wherein R18 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbons). [0169] Illustrative examples of R18CO??? groups that may be used as the capping moiety include those in which R18 is a substituted or unsubstituted monovalent hyd" . .