<sup>1</sup>H‐NMR Characterization of Epoxides Derived from Polyunsaturated Fatty Acids
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Bibliographic record
Abstract
Abstract In recent years, 1 H NMR has been used to study epoxides in lipid oxidation and industrial processes, but the peak assignments reported for monoepoxides and diepoxides have been inconsistent. Lack of clear assignments for chemical shifts of epoxides derived from polyunsaturated fatty acids (PUFA) has also limited the use of 1 H NMR in detecting and quantifying these products during both oxidative degradation and industrial epoxidation. In this study, 1 H NMR was used to characterize the epoxides synthesized from trilinolein, trilinolenin, canola oil, and fish oils by reaction with formic acid and hydrogen peroxide. Assignments for epoxides derived from PUFA in canola oil and fish oil were between 2.90–3.23 ppm and 2.90–3.28 ppm, distinct from other chemical groups in these oils. Chemical shifts of epoxy groups moved downfield with an increasing number of epoxy groups in the fatty acid chain. Hence, peaks for diepoxides appeared at 3.00, 3.09, and 3.14 ppm and for triepoxides at 3.00, 3.16, and 3.21 ppm. Results also suggested that stereoisomers of diepoxides and triepoxides were formed during the epoxidation process under the conditions of this study. These new assignments for di‐ and tri‐epoxide stereoisomers were supported by GC–MS analysis of their methyl esters, H–H COSY experiments, and a re‐evaluation of several previous epoxide‐related studies.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
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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 it