Structure of Leucine Adsorbed on Polystyrene from Nonlinear Vibrational Spectroscopy Measurements, Molecular Dynamics Simulations, and Electronic Structure Calculations
Bibliographic record
Abstract
We have used a combination of sum-frequency generation spectroscopy, molecular dynamics simulations, and electronic structure calculations to arrive at a statistical picture of the orientation and conformation of a hydrophobic amino acid on a hydrophobic polymer surface. Vibrational sum frequency spectra of leucine adsorbed at the polystyrene–solution interface appear simple in that only a few vibrational bands are evident. However, electronic structure calculations reveal 10 normal modes in the C–H stretching region between 2800–3000 cm –1 . Many of these modes are highly coupled and close in energy. Further, molecular dynamics simulations reveal that leucine adopts five conformations when adsorbed onto the surface, and has two primary preferences for the adsorbed orientation of each conformer. We have combined these results to provide a unified picture of the distribution of adsorbed molecular structures. This general approach is broadly applicable to systems where a simple correspondence between the spectral features and the vibrational normal modes is complicated due to spectral congestion, thereby providing a route for the analysis of larger molecules.
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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".