Abstract: The present invention provides an air-cooled four-stroke internal combustion engine capable of achieving a high degree of cooling. The present invention is directed to an air-cooled four-stroke internal combustion engine including a crankshaft and a fan rotor rotatably driven by the crankshaft to generate cooling air for cooling the engine. The engine comprises an oil pan disposed below the crankshaft. A space formed below the oil pan extends in the axial direction of the crankshaft along the lower surface of the oil pan and allows a cooling air to pass therethrough. An upstream portion of the lower surface is inclined upward, toward the upstream, in a vertical section taken along the axis of the crankshaft to receive the cooling air therein.

Abstract: The present invention provides an air-cooled four-stroke internal combustion engine capable of achieving a high degree of cooling. The present invention is directed to an air-cooled four-stroke internal combustion engine including a crankshaft and a fan rotor rotatably driven by the crankshaft to generate cooling air for cooling the engine. The engine comprises an oil pan disposed below the crankshaft. A space formed below the oil pan extends in the axial direction of the crankshaft along the lower surface of the oil pan and allows a cooling air to pass therethrough. An upstream portion of the lower surface is inclined upward, toward the upstream, in a vertical section taken along the axis of the crankshaft to receive the cooling air therein.

Abstract: In producing interferon by treating animal cells proliferated on a microcarrier with an interferon inducer, the cells on the microcarrier are treated with a negatively charged water-soluble macromolecular material.

Abstract: In the method of the present invention for production of interferon from propagating tissue culture cells, a propagating apparatus is utilized having a plurality of spaced-apart parallel flat plates. Monolayers of the tissue cells are grown on these plates and the apparatus is adapted for the introduction of gas and/or liquid mediums between the plates. In carrying out the method of the present invention the culture medium which nourishes the propagating cell tissues is exposed to a gas phase for oxygenating and adjusting the pH of the medium, while maintaining the culture medium and the propagated cells in a static and undisturbed condition.

Abstract: Apparatus and method for propagating tissue culture cells. A plurality of spaced-apart, parallel flat plates are assembled. The cells are grown between the plates. Gases or liquid media may be introduced between the plates.

Abstract: An apparatus for growing animal cells of this invention comprises tubes with a hole near bottom of each tube and a variable angle tube holder. Cells may be attached and proliferated in the tubes which contain a nutrient medium, which can be removed simply from the tubes through holes by changing the angle of the tubes. Cell sheets in many tubes can be washed simply, rapidly and simultaneously.