Estimation of the Cellulose Microfibril Angle in Acacia mangium Wood Using Small-Angle X-Ray Scattering
Bibliographic record
Abstract
The term microfibril angle, MFA in wood science refers to the angle between the direction of the helicalwindings of cellulose microfibrils in the secondary cell wall, S2 layer of fibres and the long axis of the cell wall.A method is presented for the measurement, using small-angle X-ray scattering (SAXS), of the microfibril angle,(MFA) and the associated standard deviation for the cellulose microfibrils in the S2 layer of the cell walls ofAcacia mangium wood. The length and orientation of the microfibrils of the cell walls in the irradiated volume ofthe thin samples are measured using SAXS and scanning electron microscope, (SEM). The undeterminedparameters in the analysis are the MFA, (M) and the standard deviation (σ?) of the intensity distribution arisingfrom the wandering of the fibril orientation about the mean value. Nine separate pairs of values are determinedfor nine different values of the angle of the incidence of the X-ray beam relative to the normal to the radialdirection in the sample. The results show good agreement. The curve distribution of scattered intensity for thereal cell wall structure is compared with that calculated with that assembly of rectangular cells with the sameratio of transverse to radial cell wall length. It is demonstrated that for β = 45° (where β is the angle between theplane face of the wood samples and the radial direction) the peaks in the curve intensity distribution for the realand the rectangular cells coincide. If this peak position is ?45, Then the MFA can be determined from the relationM = tan-1 (tan ?45 / cos 45°), which is precise for rectangular cells.
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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 | 0.001 | 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) | 0.000 | 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".