Water-network percolation transition in hydrated blue-green algae in vivo

Electric conductivity percolation in naturally dehydrating, lightly wetted, hydrophilic fumed silica powder

“…This has already been exploited, e.g., in electric conductivity studies in vitro of simple biological systems of various complexity: maize seeds [2,3], biological membranes [4], crustacean embryos [5], and protein powders [6][7][8][9], as well as in vivo in living lichens [10,11], yeast [12], and blue-green algae [13]. The conducting media are the hydrogen-bonded networks of water molecules, and conductivity is protonic in nature [8,14,15].…”

“…Thus, not only the structure of the water layer but also the degradation of the conducting network during dehydration is inhomogeneous on these surfaces. As a result, conductivity percolation with a nonuniversal exponent, μ = 1.08-1.46, is observed in these systems [4][5][6][7][8][10][11][12][13]. Despite the span, most of the values fall in the range seen when modeling conductivity percolation phenomena in 2D, both experimentally and theoretically.…”

“…The hydration threshold, in turn, is generally noninformative about water organization at the surface because it compares water mass at the threshold to dry material mass rather than to the specific surface area and morphology of the surface. Not surprisingly, the threshold values have been found to vary widely over orders of magnitude from system to system (see Table I in [13]), and quantitative interpretation has been difficult [6,11,19].…”

Note: Optimization of the numerical data analysis for conductivity percolation studies of drying moist porous systems

“…3 and references therein). In recent years, we performed DC conductivity percolation studies on drying yeast, 4 algae, 5 and different forms of thermally 3, 6 or chemically 7 conditioned granular silica. In the spectral low-frequency region (in our case, ∼f ≤ 100 kHz), the dielectric loss spectrum, ε (ω), is dominated by σ DC contribution, manifested in 8 where ε o and ω = 2π f are the permittivity of the vacuum and the electric field angular frequency.…”

“…(4), for few representative complex permittivity spectra collected during dehydration of Aerosil A150 3 and algae. 5 Figure 1 shows overlays of the genuine dielectric loss spectrum and the calculated one (2nd-order Lagrange interpolation through three adjacent [lnω i ,ε (ω i )] data points, followed by analytical differentiation) at several different hydration levels. Two features are worth a note.…”