BACKGROUND Microbioreactors have emerged as novel tools for early bioprocess development. Mixing lies at the heart of bioreactor operation (at all scales). The successful implementation of micro-stirring methods is thus central to the further advancement of microbioreactor technology. The aim of this study was to develop a micro-stirring method that aids robust microbioreactor operation and fac...

The challenge of achieving rapid mixing in microchannels is addressed through a computational fluid dynamics (CFD) study using the ADINA-F finite element program. The study is motivated by the need to design an adequate mixing chamber for aqueous chemical reactants in a micro steam generator. The study focuses on the geometric optimization of a static micromixer channel by considering the trade...

The Ehrenfest urn is a model for the mixing of gases in two chambers. Classic research deals with this system as a Markovian model with a fixed number of balls, and derives the steady-state behavior as a binomial distribution (which can be approximated by a normal distribution). We study the gradual change for an urn containing n balls from the initial condition to the steady state. We look at ...

In this paper the supersonic ejectors are experimentally and analytically studied. Ejector is a device that uses the energy of a fluid to move another fluid. This device works like a vacuum pump without usage of piston, rotor or any other moving component. An ejector contains an active nozzle, a passive nozzle, a mixing chamber and a diffuser. Since the fluid viscosity is large, and the flow is...

A perfusion chamber is described with which a tissue culture can be irrigated successively with different immersion media. Only 1-2 ml. of medium are required for each change, which can be accomplished within 1 minute. Simplicity of design permits speed and economy in manufacture. Perfusion by suction instead of by positive pressure has eliminated certain drawbacks of previous designs. Mixing e...

_I BHARMACIA GRADIENT MIXER GM-1 The prime requirement for the production of linear ionic strength gradients is efficient mixing of the components of the gradient. In the Pharmacia Gradient Mixer GM-1 this is achieved by a blade configuration which lifts the dense incoming solution from the bottom of the mixing chamber and distributes i t evenly throughout the whole eluant at a low stirring spe...

Ultrasonic contrast agents have been used to assist blood flow measurements. Several contrast-specific flow measurement techniques have been proposed during the last few years. Among them, a method based on relative enhancement of the backscattered signal as a function of time is of particular interest. This method is also known as the time-intensity method. The method is based on the indicator...