On Enthalpies of Solution of Athabasca Pentane Asphaltenes and Asphaltene Fractions
Bibliographic record
Abstract
The analysis and prediction of asphaltene precipitation behaviors and asphaltene–diluent interactions are typically treated from either a solution thermodynamics or a colloid perspective. The polydispersity and multiphase nature of asphaltenes allows for portions of these materials to exhibit both behaviors concurrently at fixed global composition. In the current work, this duality is explored using solution calorimetry. Measurements were performed for Athabasca pentane asphaltenes and asphaltene fractions in pure diluents (toluene, tetrahydrofuran, quinoline, 1-methylnaphthalene) and in diluents where impurities were intentionally added. Reported values for the enthalpy of solution in the data set range from −16 to +10 J/g of asphaltenes. The observed changes in both the magnitude and sign of the enthalpy of solution values with global composition at fixed temperature and with temperature at fixed composition are interpreted qualitatively based on enthalpies of sorption (negative), enthalpies of phase transition (positive), and enthalpies of mixing (negative or positive). Quantitation of the asphaltene fractions potentially present as colloidal particles, as an asphaltene-rich liquid or as dissolved species in a diluent remains a subject for future study.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".