Interaction of cationic surfactants with DNA detected by spectroscopic and acoustic wave techniques
Bibliographic record
Abstract
Interaction of the cationic surfactants benzalkonium chloride and 1-hexadecylpyridinium chloride, in the concentration range 0.1 microM to 1 mM with calf thymus DNA and with short 19-mer double-stranded DNA has been examined in solution using UV absorption and fluorescent spectroscopies and at the liquid-solution interface by thickness-shear mode acoustic wave sensor. Higher concentrations of surfactant resulted in an increase of UV absorption, and decrease of melting temperature and van't Hoff enthalpy of calf thymus DNA. Both surfactants induce fluorescence quenching of ethidium bromide which is also associated with intercalation of the molecules into the nucleic acid strand. The effect of the pyridinium compound is greater than for the other surfactant likely because of the lower size of polar head group in this molecule. With respect to acoustic wave detection at the device surface, for relatively low surfactant concentrations (below 100 microM), decreases of both series resonant frequency and motional resistance were observed. At higher surfactant concentration both parameters increased. These effects are attributed to acoustic coupling processes that occur at the device-film/liquid boundary.
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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 | 0.000 | 0.001 |
| 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) | 0.001 | 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 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".