Abstract: An object of the present invention is to provide a novel double-stranded RNA that has high resistance to nuclease and cellular uptake efficiency and that can produce an excellent RNA interference effect. The present invention provides a double-stranded lipid-modified RNA comprising a sense strand having a nucleotide sequence complementary to a target sequence in a target gene, and an antisense strand having a nucleotide sequence complementary to the sense strand, the double-stranded RNA being capable of suppressing the expression of the target gene, and the sense strand having a double-stranded lipid bound directly or via a linker to at least one of the first to sixth nucleotides from the 5? end.

Abstract: An admixture for cement compositions is prepared by calcining at 630.degree. to 870.degree. C. at least one substance selected from the group consisting of natural kaolin, halloysite and synthetic kaolin, effecting classification so that amorphous portions of alumina/silica having a mixing ratio of 0.5 to 1.3 form main components, with all particles having diameters up to 8 .mu.m and an average diameter of 0.5 to 2 .mu.m, and a specific gravity ranging from 2.45 to 2.55. This admixture is used to produce a cement composition such as mortar or concrete, which realizes excellent fluidity to promote workability, and a high strength structure.