Estimated bioconcentration factors (BCFs) for the C<sub>4</sub>through C<sub>8</sub>perfluorinated alkylsulfonic acid (PFSA) and alkylcarboxylic acid (PFCA) congeners
Bibliographic record
Abstract
Bioconcentration factors (BCFs) were estimated for all congeners in each of the C(4) through C(8) homologue groups for perfluorinated alkylsulfonic acids (PFSAs) and alkylcarboxylic acids (PFCAs). Predictive equations were developed between molecular areas and volumes using optimized gas-phase geometries from the AM1 and PM3 semiempirical computational basis sets and previously determined BCFs for representative straight-chain members of each contaminant class. Molecular area approaches for estimating PFSA and PFCA BCFs resulted in more variability both between and within homologue groups than the use of molecular volumes as proxies for hydrophobicity of the perfluoroalkyl chain. An increasing degree of perfluoroalkyl chain branching within each homologue group reduces the estimated BCF, suggesting that the more linear PFSA and PFCA congeners will display the highest BCFs in aquatic organisms.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".