Determining Surface Potential of the Bitumen‐Water Interface at Nanoscale Resolution using Atomic Force Microscopy
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Bibliographic record
Abstract
Abstract Atomic force microscopy (AFM) was used to measure the surface forces between a silicon nitride AFM tip and a deposited layer of Athabasca bitumen; the measurements were carried out in pure water (pH 6.0–6.5) and 1 mM KCl solution (pH 9). An AFM pyramidal‐shaped tip was moved stepwise using an operator‐controlled offset (10 nm per step) and the tip‐bitumen colloidal forces were measured at each location. Surface charge densities at the bitumen‐water interface were calculated from the measured colloidal forces using a theoretical model that combined both electrostatic and van der Waals forces for a conical tip‐flat substrate system. Fitted values of the bitumen surface charge density ranged from –0.002 to –0.004 C/m 2 in water (pH 6.0–6.5), and –0.005 to –0.022 C/m 2 in KCl solution (pH 9); the variation of local charge density along the bitumen surface appeared random. Bitumen surface potentials were also calculated from the surface charge densities using the Graham equation; the values ranged from –90 to –130 mV in water, and –45 to –110 mV in KCl solution. This study suggests the presence of bitumen surface domains of different surface charge densities/surface potentials. The domains are estimated to have characteristic sizes of 20 to 40 nm or less.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| 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 it