Asphaltene−Silica Interactions in Aqueous Solutions: Direct Force Measurements Combined with Electrokinetic Studies
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
An atomic force microscope (AFM) was used to study the interaction between asphaltenes and silica surfaces in aqueous solutions directly. Electrokinetic measurements were performed on similar systems to complement the AFM results. Asphaltene−silica interactions in aqueous solutions exhibited a time-dependent characteristic. A repulsive force component developed with increasing sample incubation time, suggesting molecular rearrangements at the asphaltene−water interface. Upon the addition of 1.0 mM KCl, the repulsive force was suppressed, and the measured force became overall attractive, implying an electrostatic nature for this repulsive force. An increase of the solution pH in the same system eliminated the attractive force regime through the development of a stronger repulsive force component. The increase in the range and magnitude of the asphaltene−silica interaction with increasing solution pH clearly indicates the presence of pH-dependent ionizable groups on the asphaltene surface. The measured long-range force can be very well accounted for by the Poisson−Boltzmann (PB) equation using a constant Stern layer potential boundary condition. The fitted Stern layer potentials of asphaltene surfaces (ψ as ) became more negative with increasing pH. In the case of asphaltenes at high solution pH values, a satisfactory agreement was obtained between the fitted Stern layer potential based on the AFM force measurements and the electrokinetic potential measured using the electrophoresis method. The swelling/stretching of surface asphaltene molecules at high solution pH and the sensitivity of such stretched layers to added salt were also evident from the force−distance data. The measured adhesion force correlated well with the long-range force behavior.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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