Effect of Ammonium Fluoride Doping on Nitrogen, Oxygen, and Methane Clathrate Hydrates
Bibliographic record
Abstract
The van der Waals diameters of N 2, O 2, and CH 4 are almost identical; however, they have different electrostatic charge distributions, and their preferred hydrate structures are different. The O 2 and N 2 molecules form structure II (sII) clathrate hydrates under moderate pressure conditions up to 1 kbar, while the CH 4 molecule forms a structure I (sI) clathrate under these pressure conditions. In this work, we investigated the effect of NH 4 F doping on N 2, O 2, and CH 4 hydrates with powder X-ray diffraction (PXRD) measurement. From the PXRD pattern analyses, the lattice parameter decreased for all three hydrates as the concentration of NH 4 F doping in the framework increased. The sizes and electrostatic charge distributions within hydrate cages were “tuned” by the NH 4 F doping, and the transition of the preferred clathrate structure of N 2 hydrate from sII to sI occurred at doping concentrations greater than 5 mol %. This transition was not observed in O 2 and CH 4 hydrates. The findings in this work reveal that the guest–host van der Waals and electrostatic interactions can be adjusted by the NH 4 F doping to the host framework and suggest that the crystal engineering of the hydrate lattice can be an alternative to improve hydrate-based gas separation technologies.
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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 | 0.000 | 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) | 0.001 | 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".