Abstract: Tetrahydro-.alpha.-pyrones and their intermediate salts of 5-hydroxy-2,3-diphenyl hexanoic acid have psychostimulant activity. A process for the preparation of these compounds comprises preparing the alkyl ester of a 5-oxo alkanoic acid from a 4-oxo alkane carbonitrile, obtained in a first stage by the action of benzyl cyanide on the corresponding alkenone, and then saponifying the obtained ester, followed by hydrogenation to form the 5-hydroxy-2,3-diphenyl hexanoic acid salt, followed if desired by cyclization to form the tetrahydro-.alpha.-pyrone.

Abstract: A process for the preparation of tetrahydro-alpha-pyrones comprises preparing the alkyl ester of a 5-oxo alkanoic acid from a 4-oxo alkane carbonitrile, obtained in a first stage by the action of benzyl cyanide on the corresponding alkenone, and then saponifying the obtained ester, followed by hydrogenation and cyclization.

Abstract: A warning device of the disconnection of a tube from another tube, for example, of a respirator canula from a patient's medical equipment comprises: a source of gas under pressure; a pneumatic switch; a filter; an adjustable pressure reducing valve; and a pneumatic cell of the fully open -- fully closed type, supplied by said pressure-reducing valve. A sensing tube terminates in at least one orifice between the walls in contact of two said tubes when they are normally connected and controls the cell. A distributor is supplied by said pressure-reducing valve and controlled at its resting input and at its working input by the cell. At least one alarm means is supplied by the distributor. The said orifice may be an open end of said sensing tube, inserted between the walls in contact of the canula and of the apparatus of the patient.

Abstract: The flow rate regulation, notably of a rapid perfusion flow rate, is effected by regulating the pressure in the perfusion reservoir by the application of a voltage to a compressor, which increases the flow rate of the liquid in the perfusion tubing by sending pressurized air into the reservoir. The latter is at atmospheric pressure when no voltage is applied to the compressor. The device comprises the combination of a perfusion reservoir and a compressor which causes the pressure in said reservoir to vary. Consequently the flow rate of the perfusion liquid delivered by the latter into the perfusion tubing varies. The compressor is governed by a differential voltage resulting from the comparison by an electronic circuit of the real value with the desired value of the flow rate in the perfusion tubing. This differential voltage is applied to the compressor which then sends compressed air into the perfusion reservoir.

Abstract: Automatic regulation system of a flow of liquid, which system comprises an electronic liquid flow control circuit connected to a liquid flow regulation device which it actuates, the said electronic circuit being characterized in that it comprises a drop counting circuit connected to a comparator circuit which comprises a bistable circuit which is itself connected on the one hand to alarm circuits and on the other hand to a monostable circuit, the magnitude of the pulse of which is compared with the magnitude of the pulse of the bistable circuit by means of a comparator circuit to which the bistable and monostable circuits are connected. Said system is used for automatic regulation of the flow of a perfusion liquid.

Abstract: 6-Methyl-3,4-diphenyl-3,4,5,6-tetrahydro-2-pyrone or derivatives thereof are psychostimulants which can be administered orally, parenterally and rectally. An effective oral dose for an adult is 100-1000 mg/day.