Abstract: (-)-Ritodrine, that is (-)-erythro-1-(p-hydroxyphenyl)-2-[2-(p-hydroxyphenyl)ethylamino]-1-propan ol or a salt thereof substantially free from the (+)-isomer is disclosed. The compound has a strong suppressive effect on uterine contraction in comparison with (.+-.)-ritodrine and (+)-ritodrine and has the same level of toxicity as these compounds, so that it can be used as a therapeutic agent of threatened premature birth and threatened abortion as well as a therapeutic agent of dysmenorrhea having a high safety.

Abstract: A mechanism for positioning the light receiving end of an optical conductor cable at the focal position of a lens comprises an optical conductor cable supporting member for supporting an optical conductor cable, and a fixing device for fixing the light-receiving end of the optical conductor cable to the cable supporting member. The fixing device comprises a cap nut provided with a slit through which the optical conductor cable is inserted in the direction of the optical axis, a male screw threaded on the cable supporting member and engaged with the cap nut, and a collar portion formed on the outer circumference of the optical conductor cable at the light-receiving end thereof.

Abstract: A lens-holding apparatus used for holding a hexagonal lens and for fixing the light receiving end of an optical conductor at the focal point of the lens includes a frame body having a hexagonal portion on at least a part thereof, a hexagonal lens tightly inserted into the hexagonal portion, and an optical conductor cable fixing mechanism for fixing the light-receiving end of the optical conductor at the focal point of the lens on another portion of the frame body. The hexagonal portion comprises six side surfaces, every other one of which has two slits formed symmetrically in relation to the center line of each side surface in the longitudinal direction for mounting the lens thereon and a tongue piece formed between both slits. The lens is tightly inserted into the hexagonal portion and held therein by means of a tongue piece for pressing the lens.

Abstract: In a hydraulic apparatus, an operating oil delivered from a fixed delivery hydraulic pump is divided into two parts, one of which is discharged into an oil tank by passing through a serial circuit consisting of a normally open valve and an orifice and the other of which is supplied to a piston-cylinder means by passing through a parallel circuit consisting of a normally closed valve and a check valve. When the normally closed valve is closed and the normally open valve is gradually closed, the piston is raised while gradually increasing in velocity. On the other hand, when the normally open valve is totally opened to stop the piston and the normally closed valve is gradually opened, the piston is lowered while gradually increasing in velocity. When the valves are operated to cause the piston to move vertically, the impact applied thereto at the time when the valve opening is large is largely mitigated by using said orifice.

Abstract: In a hydraulic apparatus, operating oil delivered from a fixed delivery hydraulic pump is divided into two parts, one end of which is discharged into an oil tank by passing through a serial circuit of a normally open valve and an orifice and the other end of which is supplied to a piston-cylinder mechanism by passing through a parallel circuit of a normally closed valve and a check valve. When the normally closed valve is closed and the normally open valve is gradually closed, the piston is raised while gradually increasing in velocity. On the other hand, when the normally open valve is totally opened to stop the piston and the normally closed valve is gradually opened, the piston is lowered while gradually increasing in velocity. When the valves are operated to cause the piston to move vertically, the impact applied thereto at the time when the valve opening is large is largely mitigated by using the orifice.