Abstract: A vacuum valve includes a housing having an operating chamber, a plunger provided in the housing; and a self-lubricating rolling diaphragm provided between the plunger and the housing. The rolling diaphragm may have a tapered form. A vacuum valve further includes a valve rod connected to the plunger and penetrating the housing to connect with a valve body. A self-lubricating shaft seal comes into contact with the valve rod to provide an airtight seal between the housing and the valve rod.

Abstract: An organic photochromic compound with improved long term preservability, thermal stability, the repetition character of the record and the like and useful as recording-memory materials or photosensitizers, comprising dimers of the compounds selected from the group consisting of pyrido[3,4-g]isoquinoline, pyrido[2,3-g]quinoline, pyrido[3,2-g]quinoline and pyrido[3,2-g]quinoline derivatives.

Abstract: A ball valve in which the ball of the valve is positively prevented from blowing out of the valve body in both directions, even if the valve is connected in the wrong direction or the fluid pressure is applied to the valve in the opposite direction. The ball is arranged in a valve body to selectively open and close a fluid passage in the body, and annular seals abut against the ball from both sides of the fluid passage, the annular seals being pushed towards the ball by seal carriers. In one embodiment, one of the seal carriers has a flange on the periphery of one end thereof, and the flange is locked to a step from inside which is formed on inner surface of one end portion of the valve body. In a second embodiment, the ball additionally has two grooves with abutting walls in respective ones of which a spindle and a pin coaxial with the spindle are fitted with the abutting walls positioned on the side of the one seal carrier.