Interactions of 6-aminopurine (adenine) in water and aqueous urea solutions
Bibliographic record
Abstract
Density (ρ), ultrasonic velocity (U), viscosity (η), and absorbance (A) of adenine in water, 1 M, 3 M, and 6 M aqueous urea solutions have been measured in the presence (and absence) of different concentrations of salts, i.e., NaCl, KCl, and CaCl2. From these measured values, the apparent molar volume (ϕv), experimental slope (Sv), apparent molar compressibility (ϕK), viscosity coefficients A and B of JonesDole equation, specific acoustic impedance (Z), hydration number (Sn), internal pressure (Pi), molar absorptivity (ε), hypochromicity (h), and oscillator strength (f) have been calculated at 298.15 K. The increasing and (or) decreasing trends of all these parameters indicate a strong interaction of urea in moderate concentration (1 M and 3 M) with adenine especially at the hydrophilic/polar and ionic sites, particularly by hydrogen bonding. However, the interaction at hydrophobic sites are relatively weaker. Higher concentrations of urea (6 M) have more denaturation effect. The ππ interactions (stacking) in adenine are more prominent in concentrated solutions and are also strengthened by the presence of cations up to an optimum concentration of salts (cut-off point). The self-association of urea and adenine is more significant in concentrated aqueous solutions and becomes negligible on dilution.Key words: interaction, adenine, urea, density, viscosity, and ultrasonic velocity.
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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 | 0.000 |
| 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 | 0.000 |
| 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".