Über die Einfachheit von Funktionenalgebren über Verbänden

Ohne Zusammenfassung     

Partition theorems for unary algebras

Those unary algebras (A, ?) (A a set, ? a mapping from A into A) are characterized for which an analog of Ramsey's theorem holds.     

Untersuchungen zur atomspektroskopischen spurenanalyse in AIIIBV-halbleiter-mikroproben—IV: Vergleich der bestimmung von tellurspuren im GaP und GaAs durch AAS,AFS und AES

Methods are described for the determination of trace tellurium in acid solution in the absence and presence of the inorganic matrices As, P, Ga, GaP and GaAs and for the direct determination in solid GaP and GAs. The following methods were used: AAS with electrothermal atomization, AFS with electrothermal atomization, and AES with d.c. arc excitation. The conditions for each of the methods were optimized and the analytical results were compared. It is shown that AAS with electrothermal atomization gives the best absolute and also relative limit of detection for trace tellurium (90 pg Te, or 4 ppm Te in GaAs or GaP). Therefore this method is recommended for the determination of trace tellurium in very small samples of A^IIIB_V-semiconductors.