Evaluation of a Wet Chemistry Method for Isolation of Cyclotron Produced [211At]Astatine
Bibliographic record
Abstract
A “wet chemistry” approach for isolation of 211At from an irradiated bismuth target is described. The approach involves five steps: (1) dissolution of bismuth target in conc. HNO3; (2) removal of the HNO3 by distillation; (3) dissolution of residue in 8 M HCl; (4) extraction of 211At from 8 M HCl into DIPE; and (5) extraction of 211At from DIPE into NaOH. Results from 55 “optimized” 211At isolation runs gave recovery yields of approximately 78% after decay and attenuation corrections. An attenuation-corrected average of 26 ± 3 mCi in the target provided isolated (actual) yields of 16 ± 3 mCi of 211At. A sixth step, used for purification of 211At from trace metals, was evaluated in seven runs. In those runs, isolated 211At was distilled under reductive conditions to provide an average 71 ± 8% recovery. RadioHPLC analyses of the isolated 211At solutions, both initial and after distillation, were obtained to examine the 211At species present. The primary species of 211At present was astatide, but astatate and unidentified species were also observed. Studies to determine the effect of bismuth attenuation on 211At were conducted to estimate an attenuation factor (~1.33) for adjustment of 211At readings in the bismuth target.
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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 | 0.001 | 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) | 0.000 | 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".