The time-dependent gas hold-up is investigated during the aeration of the Saccharomyces cerevisiae suspension, the aqueous saccharose solutions and the glycerol solutions in the external loop airlift reactor. Due to the time-dependent bubble size distribution the fraction of the small bubble hold-up in the total gas hold-up decreases with an increase of the gas¯ow rate and with a decrease of the viscosity. The course of the accumulation process of the small bubbles is described by the ®rst-order kinetic equation. The small bubble accumulation rate is investigated in the airlift reactor and the bubble column. It is showed that the small bubbles form and disappear exclusively in the riser of the airlift reactor. It is found that the small bubble-liquid mass transfer coef®cient is several times larger than the overall oxygen transfer coef®cient. List of symbolsA d m 2 cross-section of the downcomer A r m 2 cross-section of the riser B, C parameters in the equation (10) D r m diameter of the riser D d m diameter of the downcomer D BC m diameter of the equivalent bubble column with the cross-section area equal to the sum of the riser and the downcomer cross-section areas H m height of the unaerated liquid (suspension) k s A1 accumulation rate constant of the small bubbles k d s A1 disengagement rate constant of the small bubbles k L a SB s A1

Der Einfluß von Temperatr und Störstellenkonzentrastion auf den Pieowiderstandskoeffizienten P11 in n‐Silizium wird behandelt. Unter Benutzung experimenteller Daten anderer Verfasser wird die Temperatur‐ und Störstellenkonzentrationsbhängigkeit der Deformationspotentialkonstante, der Anisotropie der effektivien Masse und Relaxationszeit der Elektronen bestimmt. Die Temperaturabhängigkeit der Streumechanismen wird ebenfalls bestimmt. Die Beziehungen sind in guter Übereinstimmung mit experimentellen Daten und Theorien.