Bibliographic record
Abstract
The objective in the bleaching of mechanical pulps is to selectively remove colour-contributing components (chromophores) while simultaneously preserving pulp yield. In current practice, this involves mainly the use of hydrogen peroxide, especially when high brightness is targeted. The reactions of hydrogen peroxide bleaching, usually performed in alkaline medium, result in chromophore removal through lignin modification and/or solubilization, accompanying an inevitable removal of carbohydrates. The dissolution of lignin and carbohydrates occurs to varying extents that are determined by bleaching parameters, such as peroxide charge and alkalinity. Generally, high peroxide charge coupled with high alkalinity is essential to attaining high pulp brightness. However, this common bleaching practice causes the loss of a considerable amount of organic substances from pulp fibres, which effects the bleaching operation in many respects. For instance, removal of the materials is directly reflected in pulp yield and, in turn, becomes the source of a bleach plant's production of COD (i.e., chemical oxygen demand). Aspen is an important wood species, especially in Western Canada, in the production of market BCTMP. This manufacturing industry contributes, to a great extent, to the regional economy. Technological advances in mechanical pulping and bleaching allow the production of aspen BCTMP products of flexible properties that meet the end use requirements for a broad range of paper products [1]. One advantage of aspen CTMP is its good bleachability. The pulp is currently bleached by peroxide to a brightness of over 85 ISO, which can be used as a furnish for high brightness paper grades. Our earlier studies have shown that in bleaching brightness response is rapid, then slows down, and finally reaches a plateau from which further increasing peroxide charge only slightly increases brightness [2]. It is the final brightness increase of several units that consumes the majority of an applied bleaching chemical and causes a pronounced loss of pulp yield [3]. This high susceptibility of yield loss in the alkaline peroxide bleaching of aspen pulp could be attributed to its high content of hemicelluloses, an alkali-labile pulp component [4]. Quite naturally, one would pose a question on the likelihood of bleaching aspen pulp to high brightness by peroxide while reducing yield loss.
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".