In Situ Dehydration of Carbamazepine Dihydrate: A Novel Technique to Prepare Amorphous Anhydrous Carbamazepine
Bibliographic record
Abstract
The purposes of this project were to prepare amorphous carbamazepine by dehydration of crystalline carbamazepine dihydrate, and to study the kinetics of crystallization of the prepared amorphous phase. Amorphous carbamazepine was formed and characterized in situ in the sample chamber of a differential scanning calorimeter (DSC), a thermogravimetric analyzer (TGA), and a variable temperature x-ray powder diffractometer (VTXRD). It has a glass transition temperature of 56 degrees C and it is a relatively strong glass with a strength parameter of 37. The kinetics of its crystallization were followed by isothermal XRD, under a controlled water vapor pressure of 23 Torr. The crystallization kinetics are best described by the three-dimensional nuclear growth model with rate constants of 0.014, 0.021, and 0.032 min-1 at 45, 50, and 55 degrees C, respectively. When the Arrhenius equation was used, the activation energy of crystallization was calculated to be 74 kJ/mol in the presence of water vapor (23 Torr). On the basis of the Kissinger plot, the activation energy of crystallization in the absence of water vapor (0 Torr water vapor pressure) was determined to be 157 kJ/mol. Dehydration of the dihydrate is a novel method to prepare amorphous carbamazepine; in comparison with other methods, it is a relatively gentle and effective technique.
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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".