Abstract: The invention relates to a liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy, which contains at least one compound of formula I 1

Abstract: In a manufacturing method of a heat exchanger including a core portion having a plurality of tubes and a plurality of radiation fins connected to surfaces of the tubes, and a tank portion communicating with the tubes, a preheating step, a brazing step, a gradual cooling step and a cooling step are performed in this order. In the preheating step, temperature of the tank portion having a large heat capacity is increased earlier than that of the core portion having a small heat capacity. Therefore, the temperature of the tank portion is rapidly increased, and the temperature of the core portion is obediently increased in accordance with the temperature increase of the tank portion.

Abstract: A method for manufacturing a PNP type planar transistor, diffusing an acceptor impurity in a non-oxidizing atmosphere to form a P type emitter region in one portion of an N type base region with a first silicon oxide film as a selective mask, depositing a second silicon oxide film from vapor phase on the surface of said emitter region, diffusing selectively a donor impurity in another portion of said base region with said first and second silicon oxide films as selective masks thereby to form an N type highly doped region in said base region.