Enhanced DNA Damage Induced by Secondary Electron Emission from a Tantalum Surface Exposed to Soft X Rays
Bibliographic record
Abstract
Both thick and thin films of pGEMR-3Zf- plasmid DNA deposited on a tantalum foil were exposed to soft X rays (effective energy of 14.8 keV) for various times in air under a relative humidity of 45% (Gamma approximately 6, where Gamma is the number of water molecules per nucleotide) and 84% (Gamma approximately 21), respectively. For a thick film, the DNA damage was induced chiefly by X-ray photons. For a thin film of DNA, X-ray-induced secondary electrons emitted from the tantalum result in a substantial increase in DNA damages. Different forms of plasmid DNA were separated and quantified by agarose gel electrophoresis and laser scanning. The exposure curves for the formation of nicked circular (single-strand break, SSB), linear (double-strand break, DSB), and interduplex crosslink forms 1 and 2 were obtained for both thick and thin films of DNA. The secondary electron enhancement factor for SSBs, DSBs and crosslinks of the thin film of DNA were derived to be 3.8 +/- 0.5, 2.9 +/- 0.7 and 7 +/- 3 at Gamma approximately 6 and 6.0 +/- 0.8, 7 +/- 1 and 3.9 +/- 0.9 at Gamma approximately 21, respectively. This study provides a molecular basis for understanding the enhanced biological effects at interfaces during diagnostic X-ray examination and radiotherapy.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".