The invention provides low molecular weight or polymeric organic materials in which at least one hydrogen atom is replaced by a group of the formula where R is alkyl group, alkoxyalkyl group, alkoxy group, thioalkoxy group, aryl group or alkenyl group, in each of which one or more hydrogen atoms may be replaced and one or more nonadjacent carbon atoms may be replaced. The screw arrangement consists preferably of two parts and comprises a first resilient part, e. , a degree of difficulty in coding are calculated. Furthermore, a head cleaning apparatus for cleaning a head of a printer of the present invention may has one or more tube valve 1 or tube valve apparatus.