ABSTRACT
In this work we compare the kVp estimate between CDTN multipurpose instrument, UnforsXI and Radcal 4075 meters under different combinations of voltage and filtration. The non-invasively measurements made using x-ray diagnostic and interventional radiology devices show similar tendencies to increase the kVp estimate when aluminum filters are placed in the path of the x-ray beam. The results reveal that the kVp estimate made by the CDTN multipurpose instrument is always satisfactory for highly filtered beam intensities.
ABSTRACT
Clavulanic acid (CA), a potent beta-lactamase inhibitor, is produced by a filamentous bacterium. Here, the effect of DO and shear, expressed as impeller tip velocity, on CA production was examined. Cultivations were performed in a 4 L fermentor with speeds of 600, 800 and 1,000 rpm and a fixed air flow rate (0.5 vvm). Also, cultivation with automatic control of dissolved oxygen, at 50% air saturation, by varying stirrer speed and using a mixture of air and O(2) (10% v/v) in the inlet gas, and a cultivation with fixed stirrer speed of 800 rpm and air flow rate of 0.5 vvm, enriched with 10% v/v O(2), were performed. Significant variations in CA titer, CA production rate and O(2) uptake-rate were observed. It was also found that the DO level has no remarkable effect on CA production once a critical level is surpassed. The most significant improvement in CA production was related to high stirrer speeds.
