Semi-quantitative detection of free radicals using spin trapping and phosphorus-31 NMR spectroscopy
Bibliographic record
Abstract
In this study the effectiveness of quantitative 31P nuclear magnetic resonance (NMR) spectroscopy in conjunction with spin trapping to detect and quantify various free radical species was investigated. Initially the research was focussed on assigning the 31P NMR signals for hydroxyl and superoxide radicals and on identifying the quantitative reliability of the technique. The radical adduct reaction products (diamagnetic species), of hydroxyl (HO·) and superoxide (O2 -·) radicals with phosphorus containing nitroxides, were determined to be relatively stable and as a result the 31P NMR chemical shifts for these species were determined. Their structures were verified and quantified using 31P NMR in the presence of a phosphorus containing internal standard. The 31P NMR chemical shifts for 5-diisopropylphosphoryl-5-methyl-1-pyrroline-N-oxide (DIPPMPO) and 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) spin traps with a variety of carbon centered radicals were also determined.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.010 | 0.004 |
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".