Abstract: Provided is a cancer stem cell mass from which cells incapable of forming cancer are substantially removed and which has a characteristic property of reproducing a layered structure of a cancer tissue; a process for producing the cancer stem cell mass; and use of the cancer stem cell mass. A human cancer tissue was repeatedly grown in a NOG mouse, separated cancer cells from the grown cancer tissue, and tested and compared various cancer cell culture processes. As a result, a cancer stem cell composition which is homogeneous and is substantially free of the coexistence of cells capable of forming cancer and cells incapable of forming cancer in a mixed state can be produced successively by employing an attached culture process using a serum-free stem cell culture medium rather than a generally employed floating culture process.

Abstract: There is provided a method for producing a cushion material composed of a resin molded article with a spring structure which is so moldable as to allow the mold take any shape and size, is cheap, and resistant to collapsing, does not cause fatigue even after prolonged use, and has high shock absorbing capability and load capacity, and thus suitably used as a material of any supports on which one can sit, rest or mount such as seats of automotive vehicles, motor cycles, bicycles, electric trains, and aircraft, saddles for horse riding, chairs, sofas and beds, and a method for producing a cushion material requiring only a low cost for its disposal.

Abstract: In an apparatus for removing protective films, a groove is formed in a roller having an adhesive surface sufficient to peel off a protective film from a printed wiring board. The exposed printed wiring board, on which a dry film provided with a protective film is applied, is passed between the rollers. Thus, the protective film is peeled off from the surface of the dry film resist of the printed wiring board and adhered to the roller so as to be removed. As a result, the protective film can be removed at a high speed, and automated removal of protective films can be achieved.

Abstract: Diaminomaleonitrile which is produced by the tetramerization of hydrogen cyanide is purified by heating a crude diaminomaleonitrile in an inert liquid or in an inert atmosphere at a temperature of 90.degree. to 140.degree. C, preferably 100.degree. to 120.degree. C, and then extracting pure diaminomaleonitrile having a purity of about 99% from said heated crude diaminomaleonitrile with a solvent.

Abstract: A process for tetramerizing hydrogen cyanide to diaminomaleonitrile, wherein hydrogen cyanide is polymerized in an organic solvent in the presence of a basic catalyst and a cocatalyst of the group consisting of organic mercaptans and organic disulfides.

Abstract: The present invention relates to a plastic molding having satin finish type metallic luster. More particularly, it provides a molding of high accuracy and good appearance. The plastic molding of the present invention is produced by first applying satin finishing to the surface of the molding, providing a conductive coating thereon, applying polishing treatment on the surface of the coating, and forming a metal film thereon by metal plating.