Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1901.02502

The peculiarities of dynamic current-voltage and charge-voltage loops and transient currents of melanin under pulse hydration

S. L. Bravina·P. M. Lutsyk·A. B. Verbitsky·N. V. Morozovsky
View original source ↗Read source document ↗Export metadata ↓

Abstract

Melanin is a biopolymer with unique set of applicable physical and chemical properties. The impact of a moisture-saturated air pulse (~1 s) on dynamic current-voltage (I-V-), charge-voltage (Q-V-) and transient (I-t-) characteristics of fungal melanin thin layers was investigated. The pulse hydration gives rise to sharp increase of conductance and capacitance (by I-V-loops and I-t-curves swing), transferred charge (by Q-V-loops swing) and causes the appearance of the following peculiarities: hump-like on I-V-loops, knee-like on I-V-curves and step-like on I-t-curves. General shape of I-V-loops was modelled under low hydration by linear series-parallel RC-circuit and under high hydration by the circuit with anti-series Zener diodes as nonlinear elements. By processing of bipolar I-V-loops and I-t-curves allowing for unipolar ones, the maxima of displacement current - voltage loops were revealed and their similarity to current maxima observed under ionic space charge transfer in metal-insulator-semiconductor structures and under polarization reversal in ferroelectrics is discussed. Corresponding processing of bipolar Q-V-loops evidences general shape of obtained dielectric displacement - voltage loops characteristic to ion-conducting materials. As a reason of observed transformations, the appearance of temporal polar media with reversible ferroelectric-like polarization and ionic space charge transfer is considered. Obtained results disclose the functional capabilities of melanin based sensing devices operating in dynamic mode for both hydration and driving voltage.

Explore related subjects

physics.bio-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

S. L. Bravina, P. M. Lutsyk, A. B. Verbitsky, N. V. Morozovsky. 2019-01-06. The peculiarities of dynamic current-voltage and charge-voltage loops and transient currents of melanin under pulse hydration. https://arxiv.org/abs/1901.02502

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Biology and Physics

This article frames the relation between biology and physics by characterizing the former as a subdiscipline rather than a special case of the latter. To do this, we posit biological physics as the science of living matter in contrast to classic biophysics, the study of organismal properties by physical techniques. At the scale of the individual cell, living matter is nonunitary, i.e., not composed of aggregated subunits, and has features (e.g., intracellular organizational arrangements and biomolecular condensates) that are unlike any materials of the nonliving world. In transiently or constitutively multicellular forms (social microorganisms, animals, plants), living matter sustains physical processes that are generic (shared with nonliving matter, e.g., subunit communication by molecular diffusion in cellular slime molds), biogeneric (analogous to nonliving matter but realized through cellular activities, e.g., subunit demixing in animal embryos) or nongeneric (pertaining to sui generis materials, e.g., budding of active solids in plants). This "forms of matter" perspective is philosophically situated in the dialectical materialism of Engels and Hessen and the multilevel physicalism of Neurath and the logical empiricists. We counterpose this view to informationism and to genetic and other hierarchically reductionist physical theories of biological systems and highlight open questions regarding incompletely characterized and enigmatic forms of living matter.

physics.bio-ph↗
arXiv2026

Stabilizing by steering: Enhancing bacterial motility by non-uniform diffusiophoresis

Bacteria often traverse confined spaces to perform critical functions in symbiosis, infection, drug delivery, and soil bioremediation. While the canonical run-and-tumble strategy enables exploration, its reliance on stochastic reorientation limits efficiency under confinement. We show that salt gradients can physically steer Pseudomonas putida by biasing their runs toward salt through asymmetric diffusiophoretic forces. These gradients impose a torque strong enough to overcome Brownian rotation, aligning cells along the gradient and producing straighter, more persistent motion. This response persists in a Δ{cheA} mutant, demonstrating that canonical CheA-dependent chemotaxis is not required. We further show that when toxic organic contaminants are present, salt gradients promote bacterial dispersion toward the source despite reduced motility, suggesting potential applications in bacterial delivery for bioremediation. This work uncovers a previously unrecognized mechanism by which salt gradients direct bacterial motility, revealing a physical route to control microbial transport in complex environments.

physics.bio-ph↗
arXiv2026

Signature of mechanically induced cell extrusions in cell size distribution

How a growing tissue organizes its own homeostatic state is a central question in the physics of living matter. We show that when a growing epithelial sheet counteracts increasing cell density by mechanically squeezing cells out of its plane, a homeostatic in-plane pressure emerges as a generalization of a yield stress. We find that in the quasistatic growth limit the homeostatic state is marginally stable, with a pseudogap in the distribution of local distances to the extrusion threshold pressure. Because such mechanically induced extrusions arise from an instability of individual cells, the pseudogap is imprinted in the distribution of cell areas. This provides an image-based way to test for presence of mechanically induced extrusions and we identify this signature in the developing wing epithelium of \textit{D.~melanogaster}. We expect the same principles to apply to confined three-dimensional tissues.

physics.bio-ph↗