Abstract: Isoxazole compounds having the following general formula: ##STR1## wherein R.sup.1 represents an optionally substituted aryl group or aromatic heterocyclic group; R.sup.2 represents a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, a cycloalkenyl group, an alkoxy group, a cyano group, a carboxyl group, an alkanoyl group, an alkoxycarbonyl group or an optionally substituted carbamoyl group; R.sup.3 represents an optionally substituted amino group or a saturated heterocyclic group; X represents an oxygen atom or a sulfur atom; and n is an integer of from 2 to 6. These compounds have excellent monoamine oxidase inhibitory activity and are useful as a therapeutic agent or a preventive agent against nervous diseases such as depression.

Abstract: A process for producing a ceramic preform, which comprises mixing an alkoxysilane and fine silica powder, molding the mixture, followed by heating for de-alcoholysis.

Abstract: A method for extracting metal ions by contacting an aqueous solution containing the metal ions with an acidic phosphoric acid ester, characterized in that as the acidic phosphoric acid ester, an acidic phosphoric acid ester of the formula: ##STR1## wherein R.sup.1 is an alkylphenyl group having from 7 to 18 carbon atoms and R.sup.2 is an alkyl group having from 1 to 18 carbon atoms, is used.

Abstract: A method for extracting metal ions by contacting an aqueous solution containing the metal ions with an acidic phosphoric acid ester, characterized in that as the acidic phosphoric acid ester, an acidic phosphoric acid ester of the formula: ##STR1## wherein R.sup.1 is an alkylphenyl group having from 7 to 18 carbon atoms and R.sup.2 is an alkyl group having from 1 to 18 carbon atoms, is used.

Abstract: Yttrium ions are selectively separated by extracting the yttrium ions by contacting an aqueous solution containing hydroxyethyl ethylenediaminetriacetic acid, yttrium ions and lanthanide ions with an extracting solvent containing tributyl phosphate and an acid phosphoric ester having the formula ##STR1## wherein R.sup.1 represents hydrogen atom or an alkyl group having the formula ##STR2## wherein n is an integer of 6 to 15 and m is n-1 or n-2; and R.sup.2 represents an alkyl group having the formula ##STR3## wherein n is an integer of 6 to 15 and m is n-1 or n-2.

Abstract: Yttrium ions are selectively extracted by contacting an acid phosphoric ester with an aqueous solution containing diethylenetriaminepentaacetic acid and yttrium ions and one or more heavy rare earth (atomic number of 64 to 71) ions.