Abstract: A coating composition having (A) an alcohol dispersion which includes silica having the hydrophobic surface and dispersed in an alcohol dispersion medium, the content of silica in a solid substance being 80% by weight or more; (B) a solution including a silicone oligomer which is obtained by a reaction of an alkoxysilane with water and has an average structural unit represented by R1nSiOx/2(OH)y (OR2)z (R1 representing an alkyl group, phenyl group or vinyl group, R2 representing an alkyl group and n, x, y and z representing numbers satisfying relations: 0.8≦n≦1.7, 2<x<3.2, y>0, z>0 and y+z=4−n−x); and (C) a curing agent. The coating composition exhibits excellent storage stability after the curing agent is added, suppresses aggregation of fine silica particles in spray coating and provides coating films having a high hardness and exhibiting excellent weatherability, water resistance, chemical resistance and adhesion.

Abstract: A novel amorphous optical device contributes to economic construction of optical computers. Since economic parallel processing of signals such as image information is made possible, the novel amorphous optical device contributes also to development of optical computers capable of performing ultra-high speed and parallel processing, object recognizing apparatuses in which image optical signals are processed by using image optical signals, motion picture extracting apparatuses used for eyes of robots and object movement monitors and optical surge absorbers. An amorphous optical device which is doped with an element having a negative optical input-output characteristic to incident light, wherein the number of ions and/or atoms of the element is 1×1026 to 2.

Abstract: A glass composition for magnetic disk substrates comprising as oxides: from 66 to 80% by weight of SiO.sub.2, from 5 to 15% by weight of Al.sub.2 O.sub.3, from 3 to 8.5% by weight of Li.sub.2 O, from 0 to 3% by weight of Na.sub.2 O, from 0 to 3% by weight of K.sub.2 O, from 0.5 to 8% by weight of TiO.sub.2, from 3.5 to 8% by weight of ZrO.sub.2, from 0.5 to 3% by weight of P.sub.2 O.sub.5, from 0 to 2% by weight of Sb.sub.2 O.sub.3, and from 0 to 2% by weight of As.sub.2 O.sub.3, and having a theoretical optical basicity of 0.548 or less; a magnetic disk substrate which is prepared by forming and polishing the above glass composition, followed by chemically strengthening the polished substrate by ion exchange or by forming, heat treating, and polishing the above composition and contains Li.sub.2 O.2SiO.sub.2 and/or spodumene as the main crystalline phase.

Abstract: Transparent methyl-modified silica gel is produced by reacting methyltrialkoxysilane or a mixture thereof with a tetraalkoxy-, trialkoxy- or dialkoxysilane other than the methyltrialkoxysilane with a defined quantity of water at a neutral or acidic pH in the presence of a catalytically effective amount of a metal complex soluble in the methyltrialkoxysilane, and aging the resulting hydrolysate sol to form a gel. Self-sustained films of the transparent gel are produced by spreading the hydrolysate sol onto a nonadherent substrate followed by aging or drying. The gel finds use as a host material for doping optically functional molecules.

Abstract: A glass-ceramic magnetic disk substrate which is prepared by forming, then heat treating, and then polishing a crystallizable glass composition comprising, expressed in terms of weight percent on the oxide basis: from 20 to 45% SiO.sub.2 ; from 25 to 45% Al.sub.2 O.sub.3 ; from 10 to 25% B.sub.2 O.sub.3 ; from 2 to 12% MgO; from 0.5 to 8% TiO.sub.2 ; from 0.5 to 5% P.sub.2 O.sub.5 ; from 0 to 2% Li.sub.2 O; from 0 to 2% Na.sub.2 O; from 0 to 3% K.sub.2 O; wherein, the total of the contents of Li.sub.2 O, Na.sub.2 O and K.sub.2 O is from 0 to 5%; and wherein the magnetic disk substrate comprises a main crystalline phase consisting of at least one member selected from the group consisting of mullite and aluminum borate crystals. The glass composition can easily be formed and the disk substrate can easily be polished, has excellent mechanical strength, surface flatness, surface smoothness, chemical durability, and heat resistance, and shows no deterioration of magnetic film characteristics by alkali migration.

Abstract: A glass composition for magnetic disk substrates comprising as oxides: from 66 to 80% by weight of SiO.sub.2, from 5 to 15% by weight of Al.sub.2 O.sub.3, from 3 to 8.5% by weight of Li.sub.2 O, from 0 to 3% by weight of Na.sub.2 O, from 0 to 3% by weight of K.sub.2 O, from 0.5 to 8% by weight of TiO.sub.2, from 3.5 to 8% by weight of ZrO.sub.2, from 0.5 to 3% by weight of P.sub.2 O.sub.5, from 0 to 2% by weight of Sb.sub.2 O.sub.3, and from 0 to 2% by weight of As.sub.2 O.sub.3, and having a theoretical optical basicity of 0.548 or less; a magnetic disk substrate which is prepared by forming and polishing the above glass composition, followed by chemically strengthening the polished substrate by ion exchange or by forming, heat treating, and polishing the above composition and contains Li.sub.2 O.multidot.2SiO.sub.2 and/or spodumene as the main crystalline phase.

Abstract: A process for vitrifying liquid radioactive waste is provided.In this process, a solution of a water-soluble vitrifying-facilitating inorganic compound in liquid radioactive waste is mixed with a solution obtained by hydrolyzing an alkyl silicate and then the solution mixture is left to gel. Thereafter, the resulting gel is irradiated with microwave to calcine the gel, and the calcined gel is further heated to melt and then cooled to obtain a vitrified product.