Abstract: A clinker cooler (3) comprises a plurality of grates (5) arranged in adjacent and overlapping relation to each other for conveying hot cement clinker (11) supplied from a kiln (1). The grate (5) is formed with an air hole (20) through which air from a fan (8) is jetted toward the cement clinker via a compartment (16) to cool the cement clinker. A distribution chamber (13) is equipped to a part of the grate corresponding to a part of cement clinker which is not cooled sufficiently, and the air from the fan (14) is jetted to such part of cement clinker which is not cooled sufficiently. The quantity of air jetted from the distribution chamber is adjusted by varying a degree of opening of a damper (15).

Abstract: Disclosed are (1) a Xenopus laevis bone morphogenetic protein (BMP), (2) a DNA comprising a DNA segment coding for a Xenopus laevis BMP, (3) a transformant bearing a DNA comprising a DNA segment coding for a Xenopus laevis BMP and (4) a method for preparing the Xenopus laevis BMP which comprises culturing the described in (3), producing and accumulating the protein in a culture, and collecting the protein thus obtained. Cells transinfected or transformed with the DNA allow large amounts of the Xenopus laevis BMP mature peptides to be produced, which causes the advantageous production of the peptides, which promote the synthesis of proteoglycan and can also be utilized for analysis of the mechanism of organism, particularly human bone-cartilage morphogenetic reaction, and as therapeutic agents for osteoporosis.