Ultracold neutrons are defined and their general physical properties are explained. Their relations with modern physics and how they can be produced in laboratories are discussed. Superthermal production in superfluid liquid helium, the most promising method, is presented, quoting the results of Mark 3000, a superthermal ultracold neutron generator.
After a brief history of the International System of Units (SI), the effects of a recent revision of the Japanese Measurement Law, in particular those of its policy of mandatory use of SI units, are described together with their backgrounds. Some of the conventional units for force and pressure such as kilogram-force and Torr shall be relinquished from the official use in trade and certification activities not later than September 30, 1999 so as to harmonize with the trend in international certification systems. Major problems are explained and some countermeasures are suggested.