Effect of Help-Guest Size and Hydrogen Bonding on the Stability of N-Methylpiperidine Structure H Clathrate Hydrate
Bibliographic record
Abstract
The phase equilibrium diagram measurements, powder X-ray diffraction, and molecular dynamics simulations are used to characterize the stability, structure, and guest dynamics of the structure H (sH) N-methylpiperidine (NMP) clathrate hydrate with the difluoromethane (HFC-32) help gas. The pressure–temperature phase diagram of the NMP + HFC-32 hydrate is more stable under higher temperature–lower pressure conditions than the simple HFC-32 structure I (sI) hydrate or the sH hydrates of NMP with the methane help-gas guest compound. The hydrate with these investigated guest compounds was more stable, although the HFC-32 help-guest molecules should be comparatively large and more difficult to fit into the small and medium cages of sH hydrate. Molecular dynamics simulations show that the NMP guest molecules form hydrogen bonds with the cage water molecules in the NMP + HFC-32 sH hydrate, while similar hydrogen bonding was not observed for the sH hydrate of NMP with CH₄. The larger size and nonzero dipole moment of the HFC-32 help-gas could lead to tension in the small and medium sH cages, which could weaken the cage structures in the hydrate framework, thus enabling the formation of hydrogen bonding between the NMP molecules in the neighboring cages with the cage water molecules. This is a first case where the combination of larger help-gas molecules and hydrogen bonding of the large-cage guests was observed to help stabilize a sH hydrate phase. The newly found phenomena could be the favorable properties for sophisticated gas-storing materials with the minimum environmental impact.
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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) | 0.000 | 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".