Hydrodynamic instabilities and pattern formation in a cytoplasmic medium from yeast

Study of thin layer film evolution near bacterial cellulose membrane by Ag|AgCl electrodes in chamber with lower concentration

We used the method of measuring potential difference between two Ag|AgCl electrodes immersed directly into electrolyte solution with lower concentration and at different distances from membrane. The bacterial cellulose membrane was placed in horizontal plane in the membrane system with configurations with higher NaCl concentration and density under (A) and over the membrane (B). In both configurations at the initial moment the voltage between electrodes amounted to zero. After turning off mechanical stirring of solutions, in configuration A we observed the monotonic increase and next stabilization of voltage while in configuration B after short time dependent on the initial quotient of NaCl concentrations on the membrane we observed appearance of pulsations of measured voltage and gradual decrease of mean voltage over time. Smooth changes of voltage are connected with diffusional reconstruction of Concentration Boundary Layers (CBLs) while fast increase and subsequent pulsations of voltage are connected with the appearance of hydrodynamic instabilities (gravitational convection) near membrane imposed on diffusive reconstruction of thin layer. The time needed for the appearance of hydrodynamic instabilities in CBL depended nonlinearly on the initial ratio of electrolyte concentrations on the membrane.

Two-dimensional spectrophotometry and pseudo-color representation of chemical reaction patterns

The formation of spatio-temporal patterns in layers of chemical and biochemical media is observed and quantified by a two-dimensional spectrophotometer based on a computerized video equipment with high spatial, temporal, and intensity resolution. Images are shown, to some extent, in pseudo-colors. The use of pseudo-colors and three-dimensional perspective representations enhances the perception of the information contained in an image and the inherent order of the spatial structures.

Two-dimensional spectrophotometry with high spatial and temporal resolution by digital video techniques and powerful computers

A two-dimensional spectrophotometer having a spatial raster resolution of 512 X 512 picture elements with 256 grey levels and a time resolution of 30 images per min is assembled by combination of digital video techniques and a powerful computer system. The instrument is applied to the analysis of pattern formation processes in cytoplasmic media.