Whole cell biocatalysis is an important tool for pharmaceutical intermediates synthesis, although it is hindered by some shortcomings, such as high cost and toxicity of inducer, mass transfer resistance caused by cell membrane and side reactions. Whole-cell catalysis using N-acetyl-d-glucosamine 2-epimerase (EC 5.1.3.8) and N-acetyl-d-neuraminic acid (Neu5Ac) aldolase (EC 4.1.3.3) is a promisin...

in this research, papaya slices with dimensions of 0.5×2×5 cm3 were dried at 45 °c using a cabinet dryer in which drying air velocity and relative humidity were 0.9 m/s and 30%, respectively. the moisture diffusion coefficient of papaya was determined in this drying condition. mass transfer equation with its boundary conditions was solved based on finite difference method. finally, coefficient ...

A parallel artificial lipid membrane system was developed to mimic passive mass transfer of hydrophobic organic chemicals in fish. In this physical model system, a membrane filter-supported lipid bilayer separates two aqueous phases that represent the external and internal aqueous environments of fish. To predict bioconcentration kinetics in small fish with this system, literature absorption an...

For a multicomponent competitive adsorption of furfural and phenolic compounds, a mathematical model was builtto describe the mass transfer kinetics in a fixed bed column with activated carbon. The effects of competitive adsorption equilibrium constant, axial dispersion, external mass transfer, and intraparticle diffusion resistance on the breakthrough curve were studied for weakly adsorbed com...

A comprehensive and global sensitivity analysis was conducted under a range of operating conditions. The relative importance of mass transfer resistance versus kinetic parameters was studied and found to depend on the operating regime as follows: Operating under the optimal loading ratio of 1.90(gO(2)/m(3)/d)/(gN/m(3)/d), the system was influenced by mass transfer (10% impact on nitrogen remova...

The problem of designing the pellet characteristics for existing fixed-bed reactors has been studied. The reactor is assumed to be a unidimensional, plug-flow, heterogeneous type. Three particle shapes, two intraparticle mass transfer mechanisms, two kinds of film resistance to mass transfer and two poisoning patterns have been considered. An economic balance to both product market price and pe...

The ability to simultaneously measure both biofilm thickness and the mass transfer coefficient of an inert tracer through it provides a powerful method to study biofilm development. In this communication previously published data has been collated to interpret global trends in biofilm structure during the transition towards steady-state. It appears that sudden changes in biofilm structure (dire...