Attempt to approach the role of phenolic phenylpropenol structures in the photoyellowing of softwood mechanical pulps
Bibliographic record
Abstract
Three biphenyl (I, II, III) compounds and a benzylarylether (IV) compound were synthesized to detect and quantify the presence of phenolic phenylpropenols in unbleached, peroxide-bleached, or sodium borohydride-reduced mechanical softwood pulps. The methodology used is based on a gas chromatography mass spectrometry search of the prepared compounds in the residue obtained after ethylation, thioacidolysis, and desulfurization of the pulps. Detection of biphenyl I ([Formula: see text]4 × 106 mol g1) in unbleached and NaBH4-reduced pulps is indicative of the presence of phenolic coniferaldehyde units in these pulps. Traces of biphenyl II, found in the peroxide-bleached pulp, probably came from ferulic acid units formed by oxidation of coniferaldehyde by H2O2. No biphenyl ether III or benzylaryl ether IV were detected in the three pulps. This result indicates that phenolic phenylpropenol units are not present in softwood mechanical pulps and do not contribute to the fast part of their photoyellowing.Key words: mechanical pulp, photoyellowing, phenol, coniferyl alcohol, biphenyl.
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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 | 0.000 | 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) | 0.001 | 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 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".