Comment on “Experimental Determination of the Dependence of OH Radical Yield on Photon Energy: A Comparison with Theoretical Simulations” by Fulford et al. (<i>J. Phys. Chem. A</i> 1999, <i>103</i>, 11345−11349)
Bibliographic record
Abstract
Recently, Fulford et al. 1 have determined experimentally the dependence of the "primary" yield of • OH radicals (G • OH ), a major transient species produced in water radiolysis, 2,3 on photon energy of incident radiation using aqueous solutions of plasmid DNA as a probe to sample the number of hydroxyl radicals present at the spur expansion completion (or homogenization) time, that is, ∼10 -6 s, after the initial deposition of energy.These authors 1 measured the yield of single-strand breaks (ssb) induced within the DNA probe when irradiated with photons varying in energy from 0.28 keV (C K X-rays) to 1.25 MeV ( 60 Co γ-rays).The data, when normalized relative to the yield of ssb for 60 Co γ-rays, were then used as a measure of G • OH (taking G • OH ≈ 2.80 molecule/100 eV [that is, 0.29 µmol/J in SI units; for conversion of yield values into SI units, 1 molecule/ 100 eV ≈ 0.103 64 µmol/J] for 60 Co γ radiation at ∼10 -6 s).As the photon energy decreases from ∼1.25 MeV to 1.5 keV, the values of G • OH so obtained decrease from ∼2.80 to 0.695 molecule/100 eV, whereas there is a steep upturn in G • OH with a further decrease in photon energy from 1.5 to 0.28 keV; for this latter energy, G • OH reaches a value of ∼2.48 molecule/100 eV. 1 Several theoretical calculations (using both analytical models and stochastic simulations) for electrons 4-6 or photons 6,7 predicted such a general shape for the G • OH vs particle energy curve, with a minimum • OH radical yield occurring between 0.1 and 1 keV, in partial agreement with Fulford et al.'s experimental data. 1 Using simulated electron track structures, Pimblott and LaVerne 8 also found a turnaround in G • OH for electrons of an initial energy lower than ∼1 keV.In support of the experimental data of Fulford et al., 1 we present in this comment the results of our Monte Carlo calculations of G • OH as a function of incident electron energy in the range of 0.05-150 keV.A detailed description of our computational modeling of the radiolysis of liquid water, the cross sections employed to describe the various physical
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 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".