Izidor Sabotin

Measurement protocol for planar lipid bilayer viscoelastic properties

This paper describes how to estimate planar lipid bilayers elasticity module E and surface tension sigma by means of measuring its breakdown voltage and using Dimitrovs viscoelastic model of electric field-induced breakdown of lipid bilayers. Planar lipid bilayers (BLMs) were made of two components: 1-palmitoyl 2-oleoyl phosphatidylcholine (POPC) and 1-palmitoyl 2-oleoyl phosphatidylserine (POPS) in five different compositions. Folding method for forming planar lipid bilayers in the salt solution of 100 mM KCl was used. Breakdown voltages Ubr and membrane life times tbr were measured by means of applying linear rising voltage signals of seven different slopes. Specific capacitances cBLM of bilayers were measured with charge pulse method. Then Dimitrovs viscoelastic model was fitted to measured data allowing for estimation of elasticity module and surface tension of the lipid bilayer. Our results show that onecomponent bilayers composed from POPS were more stable and thus having higher breakdown voltages and elasticity moduli then bilayers composed of POPC. Surface tension values were similar regardless of the membrane composition. Values of the elasticity (E) and surface tension (sigma) are comparable to those published in the literature. We conclude that the protocol used, though time consuming, is an alternative to other methods used for determination of bilayers mechanical properties.

A comparative study of ultrasound, microwave and microreactor-assisted imidazolium-based ionic liquid synthesis

Abstract Synthesis of ionic liquid 1-heptyl-2,3-dimethylimidazolium bromide was accomplished with the assistance of ultrasound, microwave irradiation, and a continuously operated microreactor and was compared with a conventional laboratory scale process applying magnetic stirring and water-bath heating. Results were compared with respect to process productivity, energy consumption, and product colourisation as an indicator of its purity. By using nonconventional technologies, volumetric productivity was 10- to 30-fold superior, while energy consumption was reduced by 45%–65%. Among the alternatives tested, ultrasound-assisted synthesis was shown as the most efficient one in terms of volumetric productivity (4.40 mol l-1 h-1) and specific power consumption (909.1 W h mol-1), while microwave-assisted process was the least favourable. However, only a microreactor system enabled the synthesis of a noncoloured product resulting from very efficient mixing and temperature control. Due to significant process intensification along with high product quality and superior industrial perspectives, a continuous quaternisation within microchannels could be selected as the most promising green approach among the alternatives tested in this study. Integration of ultrasound and microreactor technology including miniaturised heat exchanger is foreseen for process intensification.

Preliminary Study on Staggered Herringbone Micromixer Design Suitable for Micro EDM Milling

This paper discusses interplay between the design of a Staggered Herringbone Micromixer (SHM) and micro Electrical Discharge Machining (EDM) milling technology. SHM consists of a main channel and many herringbone lookalike grooves at the bottom, which enhance mixing. Firstly, a brief overview on how the technological model of micro EDM milling was constructed is presented. Anticorrosive stainless steel was used as a workpiece material on the basis of which the database for the technological model was established. In the second part the technological model was used for micromixer design optimization. Different SHM designs that can be machined in the same amount of time, were compered via their mixing efficiency. Mixing efficiency was estimated by performing Computational Fluid Dynamics (CFD) simulations. The results show, that smaller and shallower grooves are not efficient in the terms of mixing. An important design parameter is also the orientation of the grooves. In the end, a favorable SHM design is presented.