Polymorphic Behavior and Crystal Habit of an Anti-Viral/HIV Drug: Stavudine
Bibliographic record
Abstract
Different characterization methods (optical microscopy, Karl Ficher titration (KF), XRPD, and solid-state FTIR) were used to identify the two polymorphs and one hydrate of stavudine. The two forms are monotropically related, and form 1 is the stable polymorph. The effects of solvent, impurities, supersaturation, and mixing on the polymorphic occurrence of stavudine are investigated in detail. Hydrogen bonding analysis is employed to qualitatively predict the role of the solvent and structurally related impurities (thymine and thymidine) on polymorphism and crystal habit of stavudine crystals. The impurities showed significant changes in the crystal habit and crystal bulk density of stavudine but had no influence on the polymorphic structure. Depending on the degree of supersaturation at T = 25 °C, a specific polymorph or a mixture of forms 1 and 2 was obtained concomitantly.
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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".