The possibility of generating high-speed shear-driven flows and their potential application in liquid chromatography

An experimental proof of principle is presented for the possibility to use a shear force field to generate a stable, chromatography enabling fluid flow through micrometer and submicrometer channels without the need for a pressure or a voltage gradient. In our setup, we were able to successfully move a color tracer plug at speeds exceeding 2 cm/s through a 0.125-microm-thick and 4-mm-wide channel, without creating a pressure drop or a pressure buildup. By showing that the speed of microchannel flows can be drastically increased by simply switching from one driving force to another, the presented experiments open the road to the development of a new type of chromatography, referred to as shear-driven chromatography, potentially offering unprecedented separation speeds and resolutions and complying perfectly with the present trend toward the miniaturization and parallelization of analytical separation equipment.

Modeling the exponential growth of filamentous fungi during batch cultivation

In certain conditions, filamentous fungi are observed to grow exponentially during batch submerged growth. It is shown for three cases, with simple mechanistic models, that an exponential growth assumption is reasonable. The basis of these models is the identification of a growth unit, and a mechanism for its doubling with a constant generation time. The importance of the variation of morphological properties within populations is demonstrated by the comparison of computer simulations of simplified models using average values and either experimental data or computer simulations of detailed stochastic models. Copyright 1998 John Wiley & Sons, Inc.