Abstract: The invention is directed to a method of producing coarse-crystalline nicotinic acid with a high degree of purity in which 3-cyanopyridine is saponified with aqueous alkali hydroxide and the nicotinic acid is allowed to crystallize out of the alkali nicotinate solution obtained in this manner under the addition of mineral acid at temperatures between 99.degree. and 135.degree. C. The pH is kept above 3.7.

Abstract: A luminescent storage screen of the type used to latently store an x-ray image in an x-ray diagnostics installation has two phosphor layers separated by and carried on a carrier disposed therebetween. The carrier is substantially transparent to x-radiation, so that the x-ray image is stored in both phosphor layers. A read-out apparatus for the storage screen includes a read-out beam generator which generates a single read-out beam which is directed at one side of the storage screen. The carrier is transmissive to the read-out beam, but is impermeable to light emitted by the phosphor layers, so that the light emitted by each phosphor layer during simultaneous read-out can be separately collected and detected. The single read-out beam simultaneously scans both phosphor layers, so that the resulting images are automatically correlated. The images are then combined in a known manner to form a single, displayed image.

Abstract: The invention relates to azaphospholenes of the type ##STR1## wherein R.sub.1 and R.sub.2 may be alkyl, aryl and aralkyl groups, processes for preparing same and the use thereof.

Abstract: The invention relates to azaphospholenes of the type ##STR1## wherein R.sub.1 and R.sub.2 may be alkyl, aryl and aralkyl groups, processes for preparing same and the use thereof.

Abstract: The invention relates to azaphospholene of the type ##STR1## wherein R.sub.1 and R.sub.2 may be alkyl, aryl and aralkyl groups, processes for preparing same and the use thereof.