Design and Simulation of an Electrostatically-Driven MEMS Micro-Mixer

Bio MEMS ( Biology Micro-electro-mechanical Systems) focus on some micro-fabricated devices including electrical and mechanical parts to study the biological system such as new polymer-based drug delivery systems for anti-cancer agents, specialized tools for minimally invasive surgery, novel cell sorting systems for high-throughput data collection, and precision measurement techniques enabled by micro-fabricated devices. Especially some micro-liquid handling devices like micro-pumps, active and passive micro-mixers that can make two or more micro-fluids mixing completely, with the chaotic advection. This kind of rapid mixing is very important in the biochemistry analysis, drug delivery and sequencing or synthesis of nucleic acids. Besides, some biological processes like cell activation, enzyme reactions and protein folding also require mixing of reactants for initiation, electrophoresis activation. Turbulence and inter-diffusion of them play crucial role in the process of mixing of different fluids. In this report, it will introduce a new kind of electromechanical active micro-mixer, which includes two inlets and one outlet under the electrostatic driven voltage. Two different fluids will enter the micro-mixer and shows different colors separately blue and red. Choosing the ANSYS for the simulation of the fluids running in the micro-mixers, we can see nearly 100% fluids that have been mixed. ANSYS is used to show the effectiveness of the micro-mixer

The Fer tyrosine kinase regulates interactions of Rho GDP-Dissociation Inhibitor α with the small GTPase Rac

<p>Abstract</p> <p>Background</p> <p>RhoGDI proteins are important regulators of the small GTPase Rac, because they shuttle Rac from the cytoplasm to membranes and also protect Rac from activation, deactivation and degradation. How the binding and release of Rac from RhoGDI is regulated is not precisely understood.</p> <p>Results</p> <p>We report that the non-receptor tyrosine kinase Fer is able to phosphorylate RhoGDIα and form a direct protein complex with it. This interaction is mediated by the C-terminal end of RhoGDIα. Activation of Fer by reactive oxygen species caused increased phosphorylation of RhoGDIα and pervanadate treatment further augmented this. Tyrosine phosphorylation of RhoGDIα by Fer prevented subsequent binding of Rac to RhoGDIα, but once a RhoGDIα-Rac complex was formed, the Fer kinase was not able to cause Rac release through tyrosine phosphorylation of preformed RhoGDIα-Rac complexes.</p> <p>Conclusions</p> <p>These results identify tyrosine phosphorylation of RhoGDIα by Fer as a mechanism to regulate binding of RhoGDIα to Rac.</p