Abstract: Provided is a manufacturing method of a silicon single crystal according to the present invention includes a melting process for generating a silicon melt containing a primary dopant, and a crystal pulling-up process that pulls up a silicon single crystal from the silicon melt. The crystal pulling-up process includes at least one additional doping process for adding a dopant raw material containing a secondary dopant into the silicon melt. A flow rate of Ar gas during a first period in which the secondary dopant is not added is set as a first flow rate, and the flow rate of Ar gas during a second period that includes a period in which the secondary dopant is added is set as a second flow rate that is greater than the first flow rate..

Abstract: Disclosed is a process for producing 3-hydroxymethyl-1-propargylimidazolidine-2,4-dione which comprises(i) reacting a compound of the formula (I) ##STR1## wherein R represents an alkyl, alkoxyalkyl or aralkyl group with a compound of the formula (II)CH.ident.C--CH.sub.2 --X (II)wherein X represents a leaving group in the presence of a base to give a 1-propargylimidazolidine-2,4-dione derivative of the formula (III) ##STR2## wherein R is as defined above and (ii) hydrolyzing this derivative of the formula (III).

Abstract: In a typical method of separating isotopes, a linear material is fed between electrodes arranged in a vacuum vessel. Joule heat is generated by supplying a current to the linear material. A vapor flow is produced by heating and evaporating the linear material. Only a specific isotope in the vapor flow is selectively ionized by radiating a laser beam on the vapor flow. The ionized isotope is separated by using at least one of electric and magnetic fields. A typical isotope separating apparatus includes a vacuum vessel, a material feeder, a power source system, a laser optical system, and an ion separating unit. The material feeder feeds a linear material containing a plurality of types of isotopes between electrodes in the vacuum vessel. The power source system supplies a current to the linear material to heat and evaporate it.