Complex Conductivity Spectra of Nonporous and Porous Hydrogels
Bibliographic record
Abstract
This paper reports complex conductivity spectra of two types of hydrogels. The first is a nonporous cross-linked polyacrylamide (PAAm), samples of which are immersed in KCl electrolytes with concentrations up to 100 mmol L –1 . Comparing these spectra with the theory of Hollingsworth and Saville for ideal electrolyte solutions highlights notable differences; these are tentatively attributed to hindered ion mobility and/or ion binding that imparts polyelectrolyte characteristics. The second is a foamed xanthan gum (XG) solution that is gelled by a coexisting polyacrylamide (PAAm) network. These XG-PAAm hydrogels are remarkably compliant, porous polyelectrolytes, which can be subjected to large compressive strain ϵ x, and used to interpret the conductivity and relative dielectric permittivity on the basis of the void fraction ϕ and aspect ratio γ varying with ϵ x . Here, ϕ decreases from the initial value ϕ = ϕ 0 ≈ 0.77, where the voids are a dense network of connected spheres, to the limit in which ϕ → 0 as ϵ x → ϕ 0 ≈ 0.77. The data are very well described by continuum theories for gas spheroids embedded in conducting and dielectric media. However, despite the conductivity spectra bearing qualitative similarities to those of ideal electrolyte solutions, the effective ion mobilities and concentrations required to establish such parallels are profoundly different. Together, the impedance analysis of PAAm and XG-PAAm hydrogels provides quantitative and qualitative evidence that ion transport in hydrogels─even conventionally ideal and uncharged hydrogels─is distinctly different from their ideal electrolyte counterparts. These insights may translate to interpreting complex biological media, pertinent to bioelectrical impedance analysis and studies of subcellular phase-separated domains.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".