A simple method for assaying extracellular hydroxyl radical activity and its application to natural and synthetic waters
Bibliographic record
Abstract
An assay has been developed to measure extracellular hydroxyl radical (OH*) activity in algal culture media and natural waters over a 4- to 5-day period. The first-order rate constant, k, for loss of absorbance at 590 or 620 nm was determined for erioglaucine, which is sensitive to OH*, insensitive to superoxide and hydrogen peroxide, and stable in the dark and under artificial radiation (280750 nm) and solar radiation in the absence of oxidants. Variation in irradiance was accounted for by normalizing k with k for a ferric iron reference solution with dye (k/kfe). Trends in k/kfe for streams and lakes were consistent with previous data on photochemical oxidation rates of dissolved organic matter. Values for k/kfe were similar in filtered surface waters of eutrophic Heart Lake and nearby mesotrophic Lake St. George under artificial radiation. Hence, extracellular OH* did not appear to be a direct cause of the onset of a nuisance cyanobacterial bloom in Heart Lake, nor did OH* appear related to the absence of a bloom in Lake St. George. k/kfe was two orders of magnitude higher in algal culture media supplied with 8.8 mM nitrate than in lake waters.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".