Understanding solution-state noncovalent interactions between xenobiotics and natural organic matter using 19F/1H heteronuclear saturation transfer difference nuclear magnetic resonance spectroscopy
Bibliographic record
Abstract
A combination of forward and reverse heteronuclear ((19)F/(1)H) saturation transfer difference (STD) nuclear magnetic resonance (NMR) spectroscopic techniques were applied to characterize the noncovalent interactions between perfluorinated aromatic xenobiotics and dissolved humic acid. These NMR techniques produce detailed molecular-level descriptions of weak noncovalent associations between components in complex environmental mixtures, allowing the mechanisms underlying these interactions to be explored; (19)F observed heteronuclear STD (H-STD) is used to describe the average molecular orientation of the xenobiotics during their interactions with humic acid, whereas (1)H observed reverse-heteronuclear STD (RH-STD) is used to both identify and quantify preferences exhibited by xenobiotics for interactions at different types of humic acid moieties. First, by using H-STD, it is shown that selected aromatic organofluorides orient with their nonfluorine functional groups (OH, NH(2), and COOH) directed away from humic acid during the interactions, suggesting that these functional groups are not specifically involved. Second, the RH-STD experiment is shown to be sensitive to subtle differences in preferred interaction sites in humic acid and is used here to demonstrate preferential interactions at aromatic humic acid sites for selected aromatic xenobiotics, C(10)F(7)OH, and C(6)F(4)X(2), (where X = F, OH, NH(2), NO(2), or COOH), that can be predicted from the electrostatic potential density maps of the xenobiotic.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".