Comparison between X-ray Photon and Secondary Electron Damage to DNA in Vacuum
Why this work is in the frame
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Bibliographic record
Abstract
Both monolayer and thick (20 microm) films of dry pGEM-3Zf(-) plasmid DNA deposited on tantalum foil were exposed to Al Kalpha X-rays (1.5 keV) for various times in an ultrahigh vacuum chamber. For monolayer DNA, the damage was induced mainly by low energy secondary electrons (SEs) emitted from the tantalum. For the thick films, DNA damage was induced chiefly by X-ray photons. Different forms of plasmid DNA were separated and quantified by agarose gel electrophoresis. The exposure curves for the formation of nicked circular (single strand break, SSB), linear (double strand break, DSB), and interduplex cross-link forms 1 and 2 were obtained for both monolayer and thick films of DNA, respectively. The lower limits of G values for SSB and DSB induced by SEs were derived to be 86 +/- 2 and 8 +/- 2 nmol J(-1), respectively. These values are 1.5 and 1.6 times larger than those obtained with 1.5 keV photons. The projected X-ray energy dependence of the low energy electron (LEE) enhancement factor for the SSB and DSB in monolayer DNA is also discussed. This new method of investigation of the SE-induced damage to large biomolecules allows direct comparison of the yield of products induced by high energy photons and LEEs under identical experimental conditions.
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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 | 0.001 |
| 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 it