The Experts below are selected from a list of 3078 Experts worldwide ranked by ideXlab platform
Masanori Kobari - One of the best experts on this subject based on the ideXlab platform.
-
A population balance model for solvent-mediated polymorphic transformation in unseeded solutions
CrystEngComm, 2014Co-Authors: Masanori Kobari, Noriaki Kubota, Izumi HirasawaAbstract:A new population balance model for solvent-mediated polymorphic transformation is presented. The model takes into account the secondary nucleation caused by nuclei grown crystals as well as the primary nucleation. Numerical simulation was performed for crystallization of a hypothetical enantiotropic dimorphic compound in an unseeded solution. In the simulation, particular attention was paid to the effect of secondary nucleation of the stable polymorph on the transformation time. The simulated transformation time decreased with an increase in the secondary nucleation rate of the stable polymorph. Reported experimental data on the effect of Stirrer Speed were explained by the secondary nucleation-mediated mechanism, in which the secondary nucleation rate is assumed to increase with an increase in Stirrer Speed. The effect of scale-up on the transformation time was also suggested to be explained by the secondary nucleation-mediated mechanism.
-
secondary nucleation mediated effects of Stirrer Speed and growth rate on induction time for unseeded solution
CrystEngComm, 2012Co-Authors: Masanori Kobari, Noriaki Kubota, Izumi HirasawaAbstract:Simulation of induction time for nucleation was performed under isothermal conditions for unseeded aqueous solutions of different concentrations. The effects of Stirrer Speed and growth rate on induction time were both explained with the proposed secondary nucleation-mediated mechanism. The effect of Stirrer Speed Nr was incorporated into the simulation with an empirical relation of kb2 ∝ Nrj, where kb2 is the coefficient in the secondary nucleation rate equation B2 = kb2 (ΔT)b2μ3, ΔT is supercooling, j and b2 are empirical constants and μ3 is the third moment of crystal size distribution. The simulated induction time decreased with an increase in Stirrer Speed at lower supercoolings, while it remained unchanged at higher supercoolings. Such action of Stirrer Speed was similar to that observed in the literature data. The growth rate effect was considered to be caused by a faster increase in the secondary nucleation rate via a faster increase in μ3. The simulated induction time decreased with an increase in crystal growth rate. This type of growth rate effect is completely different from the existing mechanism considering the time needed for invisible nuclei to grow to a detectable size.
K. Schügerl - One of the best experts on this subject based on the ideXlab platform.
-
The influence of preculture on the process performance of penicillin V production in a 100-l air-lift tower loop reactor
Applied Microbiology and Biotechnology, 1992Co-Authors: J. Möller, J. Niehoff, S. Hotop, M. Dors, K. SchügerlAbstract:The influence of Stirrer Speed in the third preculture on the performance of penicillin V production by Penicillium chrysogenum in complex medium in a 100-l air-lift tower loop reactor was investigated. The process performance in the main culture was improved by increasing the Stirrer Speed from 500 to 750 rpm: the pellet size was reduced to half, the cell growth was influenced only slightly, but the production phase was extended considerably, and the final penicillin concentration was increased from 5.1 g 1^-1 to 10.4 g 1^-1.
Izumi Hirasawa - One of the best experts on this subject based on the ideXlab platform.
-
A population balance model for solvent-mediated polymorphic transformation in unseeded solutions
CrystEngComm, 2014Co-Authors: Masanori Kobari, Noriaki Kubota, Izumi HirasawaAbstract:A new population balance model for solvent-mediated polymorphic transformation is presented. The model takes into account the secondary nucleation caused by nuclei grown crystals as well as the primary nucleation. Numerical simulation was performed for crystallization of a hypothetical enantiotropic dimorphic compound in an unseeded solution. In the simulation, particular attention was paid to the effect of secondary nucleation of the stable polymorph on the transformation time. The simulated transformation time decreased with an increase in the secondary nucleation rate of the stable polymorph. Reported experimental data on the effect of Stirrer Speed were explained by the secondary nucleation-mediated mechanism, in which the secondary nucleation rate is assumed to increase with an increase in Stirrer Speed. The effect of scale-up on the transformation time was also suggested to be explained by the secondary nucleation-mediated mechanism.
-
secondary nucleation mediated effects of Stirrer Speed and growth rate on induction time for unseeded solution
CrystEngComm, 2012Co-Authors: Masanori Kobari, Noriaki Kubota, Izumi HirasawaAbstract:Simulation of induction time for nucleation was performed under isothermal conditions for unseeded aqueous solutions of different concentrations. The effects of Stirrer Speed and growth rate on induction time were both explained with the proposed secondary nucleation-mediated mechanism. The effect of Stirrer Speed Nr was incorporated into the simulation with an empirical relation of kb2 ∝ Nrj, where kb2 is the coefficient in the secondary nucleation rate equation B2 = kb2 (ΔT)b2μ3, ΔT is supercooling, j and b2 are empirical constants and μ3 is the third moment of crystal size distribution. The simulated induction time decreased with an increase in Stirrer Speed at lower supercoolings, while it remained unchanged at higher supercoolings. Such action of Stirrer Speed was similar to that observed in the literature data. The growth rate effect was considered to be caused by a faster increase in the secondary nucleation rate via a faster increase in μ3. The simulated induction time decreased with an increase in crystal growth rate. This type of growth rate effect is completely different from the existing mechanism considering the time needed for invisible nuclei to grow to a detectable size.
J. Möller - One of the best experts on this subject based on the ideXlab platform.
-
The influence of preculture on the process performance of penicillin V production in a 100-l air-lift tower loop reactor
Applied Microbiology and Biotechnology, 1992Co-Authors: J. Möller, J. Niehoff, S. Hotop, M. Dors, K. SchügerlAbstract:The influence of Stirrer Speed in the third preculture on the performance of penicillin V production by Penicillium chrysogenum in complex medium in a 100-l air-lift tower loop reactor was investigated. The process performance in the main culture was improved by increasing the Stirrer Speed from 500 to 750 rpm: the pellet size was reduced to half, the cell growth was influenced only slightly, but the production phase was extended considerably, and the final penicillin concentration was increased from 5.1 g 1^-1 to 10.4 g 1^-1.
A. K. Dikshit - One of the best experts on this subject based on the ideXlab platform.
-
Decolourization of anaerobically digested and polyaluminium chloride treated distillery spentwash in a fungal stirred tank aerobic reactor
Biodegradation, 2011Co-Authors: S. S. Singh, A. K. DikshitAbstract:Decolourization of anaerobically digested and polyaluminium chloride treated distillery spentwash was studied in a fungal stirred tank aerobic reactor without dilution of wastewater. Aspergillus niger isolate IITB-V8 was used as the fungal inoculum. The main objectives of the study were to optimize the Stirrer Speed for achieving maximum decolourization and to determine the kinetic parameters. A mathematical model was developed to describe the batch culture kinetics. Volumetric oxygen transfer coefficient ( k _L a ) was obtained using dynamic method. The maximum specific growth rate and growth yield of fungus were determined using Logistic equation and using Luedeking–Piret equation. 150 rpm was found to be optimum Stirrer Speed for overall decolourization of 87%. At the optimum Stirrer Speed, volumetric oxygen transfer coefficient ( k _L a ) was 0.4957 min^−1 and the maximum specific growth rate of fungus was 0.224 h^−1. The values of yield coefficient ( Y _ x /s) and maintenance coefficient ( m _s) were found to be 0.48 g cells (g substrate)^−1 and 0.015 g substrate (g cells)^−1 h^−1.
