Strain rate experimentally achieved

It is possible, however, to obtain generalized concentration-invariant curves under straining rates close to those used in the real-scale commercial process. In [163, 164, 209] the generalized curves for PE based composites were obtained by the procedure described in [340] by carrying out nonrotationa shifts in the vertical and horizontal directions the authors sought to achieve the closest coincidence between the experimental curves in the lg t] — lg x coordinates for the base polymer and the curves for filled composites. 

Materials can show linear and nonlinear viscoelastic behavior. If the response of the sample (e.g., shear strain rate) is proportional to the strength of the defined signal (e.g., shear stress), i.e., if the superposition principle applies, then the measurements were undertaken in the linear viscoelastic range. For example, the increase in shear stress by a factor of two will double the shear strain rate. All differential equations (for example, Eq. (13)) are linear. The constants in these equations, such as viscosity or modulus of rigidity, will not change when the experimental parameters are varied. As a consequence, the range in which the experimental variables can be modified is usually quite small. It is important that the experimenter checks that the test variables indeed lie in the linear viscoelastic region. If this is achieved, the quality control of materials on the basis of viscoelastic properties is much more reproducible than the use of simple viscosity measurements. Non-linear viscoelasticity experiments are more difficult to model and hence rarely used compared to linear viscoelasticity models. 

EMA is a useful metabolic pathway analysis tool for rational strain design and metabolic pathway evolntion of designed strains. EMA is entirely based on the strnctnral analysis of invariant metabolic networks withont reqniring kinetics parameters or experimental flnx data, snch as substrate uptake or secretion rates, which enables the prediction of genetic modifications (e.g. gene deletion and over- or down-expression) to reprogram microbial metabolic pathways and achieve desirable phenotypes. 

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