Formation of Porous Aluminophosphate Frameworks Monitored by Hyperpolarized <sup>129</sup>Xe NMR Spectroscopy
Bibliographic record
Abstract
The formation of two aluminophosphate frameworks, AlPO 4 -5 and AlPO 4 -18, has been monitored using hyperpolarized 129 Xe NMR as a probe. The reaction progress from an amorphous phase to AlPO 4 -5 and its subsequent conversion to AlPO 4 -18 is observed for xenon adsorbed in samples that have been reacted for varying lengths of time. The extreme sensitivity of 129 Xe chemical shifts to local environments of the xenon leads to separate NMR peaks for xenon adsorbed in the two different aluminophosphate frameworks present in a single reaction mixture. For xenon adsorbed in AlPO 4 -5, an anisotropic 129 Xe NMR line shape at δ iso ≈ 63 ppm is observed, whereas for xenon in AlPO 4 -18, a peak with a small anisotropy at δ iso ≈ 74 ppm is observed. Grand canonical Monte Carlo simulations provide a theoretical description of xenon adsorbed in the two aluminophosphate frameworks, and the resulting simulated 129 Xe NMR line shapes are in good agreement with experimental data. Two-dimensional exchange NMR spectroscopy was used to examine the exchange of xenon between AlPO 4 -5, AlPO 4 -18, and bulk xenon gas. The results indicate that the domains of AlPO 4 -5 are in intimate contact with those of AlPO 4 -18, facilitating a higher intercrystallite exchange than with the bulk xenon gas.
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How this classification was reachedexpand
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) | 0.001 | 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 teacher head, 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".