Speed limits, overcoming

The DFT/COSMO calculations are the rate-limiting part of the method and can easily take a few hours for molecules with up to 40 heavy atoms on a 3-GHz computer [36]. To overcome speed limitations, the authors developed the COSMOfrag method. The basic idea of this method is to skip the resource-demanding quantum chemical calculations and to compose a profiles of a new molecule from stored a profiles of precalculated molecules within a database of more than 40000 compounds. A comparison of the full and fragment-based versions for log P prediction was performed using 2570 molecules from the PHYSPROP [37]. RMSE values of 0.62 and 0.59 were calculated for the full COSMO and COSMOfrag methods, respectively [36]. 

Interestingly, Martin et al. [1986] may have finessed the field of nonpulsatile models by overcoming the speed limitations associated with pulsatile models. They did this by solving the pulsatile model equations... 

To overcome this limitation, a series of images of an entire field of cells can be obtained, then the waves can be visualized when the images are played back in rapid sequence. Specific lines of analysis can then be chosen after the experiment is completed. The line is selected to be perpendicular to the wave front (that is, along the direction of propagation). As before, the lines are stacked on top of one another, yielding a reconstructed line scan that contains all the information of a true line scan. The leading edge of the Ca2+ wave appears on the line scan as a sharp line with a constant slope. Since the slope is distance/time, appropriate conversion factors allow true speeds to be obtained in jUm/s. 

Chromatographic columns packed with conventional porous particles meet these requirements only to a limited extent. Slow diffusion of large molecules limits the speed of the separation due to the low rate of intraparticle mass transfer [7]. New approaches have been introduced to overcome this problem including ... 

The replacement of classical textile printing techniques by digital printing techniques (ink-jet and bubble jet) is in full progress. Present limitations result from the availability of appropriate formulations of inks/dyes and fixation techniques. The comparable low production speed and limitations with regard to the quality of the textile material can be expected to be overcome within the next 5-10 years. 

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