Abstract: Disclosed is a door sealing mechanism for sealing the gap between two doors or that gap between one door and the doorframe so as to prevent leakage of the inside conditioned air to the outside or entrance of the outside dust, smoke, and insects into the room. The sealing mechanism includes a blocking mechanism enclosed in a sidepiece provided on the first door and consisted of a blocking member, a movable member supporting the block member, and elastic element means coupled to the movable member. On the opposite side, a curved recess or a cushioning mechanism is provided that receives the blocking member. When the door unit is closed, the blocking member comes into air-tight contact with the curved recess or the cushioning mechanism due to the elasticity of the elastic element; and when opening the door unit, the blocking member can slide away smoothly. Furthermore, with the provisions of bumping members, noises generated by metal collisions when opening or closing the door unit is substantially eliminated.

Abstract: A semi-synthetic two-stroke engine oil formulation which comprises a base oil consisting of a high-viscosity mineral oil, a medium-viscosity mineral oil, a solvent and a mixture of three polyisobutylenes with different molecular weights, and appropriate detergents and dispersants. This semi-synthetic two-stroke engine has both high lubricity and high detergency, and also meets the requirements of low smoke and low exhaust system blocking.