Chain Length of Free Fatty Acids Influences the Phase Behavior of Stratum Corneum Model Membranes
Bibliographic record
Abstract
The skin, the largest organ of the human body, forms a flexible interface between our internal and external environment that protects our organism from exogenous compounds as well as excessive water loss. The stratum corneum (SC), the outermost layer of mammal epidermis, is mainly responsible for the skin impermeability. The SC is formed by corneocytes embedded in a lipid matrix, which is mostly constituted of ceramides (Cer), free fatty acids (FFA), and cholesterol (Chol), organized in two coexisting crystalline lamellar phases. This arrangement of lipids is crucial to skin barrier function. The aim of this paper is to determine the impact of FFA chain length on the phase behavior of SC model lipid membranes using solid-state deuterium NMR and IR spectroscopy. We studied ternary mixtures of N-lignoceroyl-d-erythro-sphingosine (Cer24), cholesterol, and palmitic (FFA16) or lignoceric (FFA24) acid in an equimolar ratio. This proportion replicates the lipid composition found in the SC lipid matrix. Our studies revealed that the phase behavior of Cer24/FFA/Chol ternary mixtures is strongly affected by the length of the FFA. We found the formation of phase-separated crystalline lipid domains when using palmitic acid whereas the use of lignoceric acid results in a more homogeneous mixture. In addition, it was observed that mixtures with lignoceric acid form a gel phase, a very unusual feature for SC model mixtures.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".