Abstract: A method for forming removable dentures using injection molding techniques wherein a cyanoacrylate base material is applied to the sides of the denture teeth, an activator or accelerator compound being sprayed onto the deposited base material whereby the base material is rapidly cured. The denture is then placed in the lower half of a mold, or flask, and a plurality of sprues are positioned therein. The upper flask portion is then attached to the lower half and the assembled flask is then invested with plaster material. The activated gel enables the teeth to be retained in position in the lower half of the flask. The flask is then placed in hot or boiling water and then deflasked to remove the melted wax. The flask is then reassembled and polymer injected therein filling the areas previously occupied by the wax. After the polymer is cured, the prothesis is removed, polished and then returned to the dentist.

Abstract: An industrially excellent, novel process for producing cephem compounds which are useful as medicines, particularly, antibiotics and represented by the following formula (III): ##STR1## wherein R.sup.1 means either group represented by the following formula: ##STR2## R.sup.2 denotes a carboxyl group or a carboxyl anion, and R.sup.3 stands for a lower alkyl group, a halogen atom, a lower alkyl group substituted by an aliphatic acyloxy group having 1-6 carbon atoms, or any one of the groups represented by the following formulae: ##STR3## which comprises reacting in water a 3-cephem-4-carboxylate represented by the following formula (I): ##STR4## or a salt thereof with an acid chloride represented by the formula (II), R.sup.1 COCl.

Abstract: Disclosed herein is a purification method of a crude product by column chromatography on silica gel or on a vinyl alcohol copolymer. Methanol-containing n-hexane and/or n-hexane-containing methanol is used as an eluent to elute the crude product, thereby obtaining an intended product with high purity and good yield. The solvents recovered from the effluent can be regenerated without any trouble such as rectification and a great cost by mixing them under stirring and then separating the resulting upper and lower layer from each other. The column used can also be reused again and again by washing with methanol. The separation and purification method is excellent in separation efficiency, operation efficiency and economical efficiency.