Phase Behavior of Athabasca Bitumen
Bibliographic record
Abstract
The phase behavior of Athabasca bitumen (Alberta, Canada) was determined from nanofiltered permeates and retentates with pentane-asphaltene mass fractions w A ranging from 0.053 to 0.57, and chemically separated Athabasca pentane maltenes and pentane asphaltenes based on differential scanning calorimetry and rheology measurements from (190 to 570) K at atmospheric pressure. Samples were subject to two sequential heating cycles. Composition, apparent heat-capacity, and phase-angle data were collected and interpreted jointly to define phase diagrams for nanofiltered maltene + nanofiltered asphaltene pseudobinary mixtures for each heating cycle. These pseudocomponents are shown to behave independently. During the first heating cycle, observed phase transitions for maltenes include: a broad low-temperature glass transition with a T g from (215 to 230) K and a small first-order phase transition with a peak temperature T trs between (320 and 340) K linked to a fraction of Athabasca maltenes undergoing a crystal to liquid transition. These transitions were found in both chemically separated and nanofiltered maltenes. Nanofiltered asphaltenes undergo a two-stage transition from solid to liquid between (260 and 470) K, with the second stage being a glass type transition. The nature of the first stage requires additional study. By contrast, chemically separated pentane asphaltenes undergo a complex transformation from (310 to 530) K comprising overlapping processes including endothermic transitions from solid-to-liquid and solid-to-liquid crystals and an exothermic dissolution of the liquid crystals [Bagheri, S. R., et al. Energy Fuels 2010, 24, 4327–4332]. Athabasca bitumen comprises a minimum of four phases drawn from liquid, crystalline maltene + glass and/or crystal, and liquid asphaltenes from (260 to 360) K. The phase transition reversibility is discussed, and the phase diagram for Athabasca bitumen is compared with that of Maya crude oil, reported previously [Fulem, M., et al. Fluid Phase Equilib. 2008, 272, 32–41]. Multiphase behavior appears to be a general phenomenon, but phase diagram details appear to vary from feedstock to feedstock.
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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) | 0.001 | 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".