Spectroscopic Observations and Thermodynamic Calculations on Clathrate Hydrates of Mixed Gas Containing Methane and Ethane: Determination of Structure, Composition and Cage Occupancy
Bibliographic record
Abstract
Clathrate hydrates of methane−ethane mixed gases have two crystal structures depending on their composition. To study their compositions and cage occupancies and how their structure is determined, we synthesized hydrate samples from methane−ethane mixtures. Analysis of the samples using X-ray diffraction, Raman spectroscopy, and gas chromatography revealed their structures, compositions, and cage occupancies. Experimentally, hydrate structure II existed in samples formed when the gas equilibrated with hydrates was approximately 2% C 2 H 6 (molar fraction) whereas both structures I (sI) and II (sII) coexisted for 12 to 22% C 2 H 6 . The structures below 2% and above 22% of C 2 H 6 existed only as sI hydrates. Volume ratios of both structures were obtained from the ratio of the peak intensities of the C−C stretching peaks in the Raman spectra. In the transition zone containing both structures, the volume ratio of the sII structure gradually decreased with increasing C 2 H 6 concentration. Cage occupancies of guest molecules in the hydrate cages were determined by the relative intensity ratio of Raman spectra. C 2 H 6 molecules occupied only large cages in both structures, whereas CH 4 molecules occupied the remaining cages. The experiments agree with the structure and molecular distributions that were predicted by minimizing the Gibbs free energy of the sample. This model calculation provides insight into the structural transition mechanism.
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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".