Thickness Dependence of the Diffusivity and Solubility of Cyclohexane in Nanoscale Bitumen Films
Bibliographic record
Abstract
Abstract Diffusivity and solubility of cyclohexane in nanoscale bitumen films coated on hydrophilic substrates at ambient conditions were studied using a gravimetric analyzer. Three substrates were used, and they are as follows: sample A, monodisperse spherical glass beads; sample B, polydisperse spherical glass beads mixed with polydisperse irregular-shape kaolin clay particles; and sample C, irregular-shape residual solids generated from a solvent extraction process of an oil sand ore. All of the above samples had a mean diameter of 150 μm. Diffusion coefficients were determined based upon the initial rates of cyclohexane absorption when bitumen-coated samples at various amounts (thicknesses) were exposed to a carrier gas with cyclohexane vapors at two levels of relative saturations (RSs), and they were found to be in the range of 10–18 to 10–16 m2/s. A double-first-order kinetics model fits well to the absorption data, suggesting that there exists a concentration gradient of polar (or nonpolar) bitumen molecules in the nanoscale films. This is because the hydrophilic substrates attract the relatively polar fraction of bitumen molecules to the region close to the substrates and the nonpolar fraction resides in the region near the free surface. As a result, the measured diffusion coefficients exhibited positive thickness dependence when the thickness of the bitumen films was at the nanoscale. The molecules near the substrates tended to diffuse slower than those in the free surface region. However, diffusivity was insensitive to the cyclohexane RS. On the other hand, the measured solubility of cyclohexane in the nanoscale bitumen films exhibited no thickness dependence but strong cyclohexane RS dependence. These results suggest that solubility is not affected by the inhomogeneous distribution of bitumen molecules in the nanoscale films and that it follows more or less Henry’s law.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 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) | 0.002 | 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".