An approximate method for nonlinear diffusion applied to enzyme inactivation during drying

An approximate model was developed for nonlinear diffusion with a power-function variation of the diffusion coefficient with concentration. This model may serve for the computation of desorption times and concentration profiles in non-shrinking or shrinking slabs, cylinders or spheres, under isothermal as well as non-isothermal conditions.For the kinetics for thermal enzyme inactivation, a relation was postulated, which includes a possible moisture dependence of the inactivation rate, which was tested by experiments with soy bean lipoxygenase, entrapped in a glucosecalciumalginate gel.The model was applied to the simulation of enzyme inactivation during drying and tested by drying experiments with soy bean lipoxygenase in the above-mentioned model material.Good agreement was observed between the results, obtained with the approximate model, the numerical solution of the complete model and the experimental results

X-wave mediated instability of plane waves in Kerr media

Plane waves in Kerr media spontaneously generate paraxial X-waves (i.e. non-dispersive and non-diffractive pulsed beams) that get amplified along propagation. This effect can be considered a form of conical emission (i.e. spatio-temporal modulational instability), and can be used as a key for the interpretation of the out of axis energy emission in the splitting process of focused pulses in normally dispersive materials. A new class of spatio-temporal localized wave patterns is identified. X-waves instability, and nonlinear X-waves, are also expected in periodical Bose condensed gases.Comment: 4 pages, 6 figure

An approximate method for nonlinear diffusion applied to enzyme inactivation during drying

An approximate model was developed for nonlinear diffusion with a power-function variation of the diffusion coefficient with concentration. This model may serve for the computation of desorption times and concentration profiles in non-shrinking or shrinking slabs, cylinders or spheres, under isothermal as well as non-isothermal conditions.For the kinetics for thermal enzyme inactivation, a relation was postulated, which includes a possible moisture dependence of the inactivation rate, which was tested by experiments with soy bean lipoxygenase, entrapped in a glucosecalciumalginate gel.The model was applied to the simulation of enzyme inactivation during drying and tested by drying experiments with soy bean lipoxygenase in the above-mentioned model material.Good agreement was observed between the results, obtained with the approximate model, the numerical solution of the complete model and the experimental results