Molecular Organization Revealed by Time-of-Flight Secondary Ion Mass Spectrometry of a Clinically Used Extracted Pulmonary Surfactant
Bibliographic record
Abstract
Pulmonary surfactant lowers the surface tension of the lung air−liquid interface to prevent alveolar collapse. It is composed mainly of saturated and unsaturated phosphatidylcholines and phosphatidylglycerols. Solvent-spread films of a pulmonary surfactant, bovine lipid extract surfactant (BLES), form liquid condensed and liquid expanded phases with changing surface pressures, as seen by fluorescence and atomic force microscopy. Time-of-flight secondary ion mass spectrometry conducted in an imaging mode below the static limit provides a novel means of mapping the identities of the molecular species present in each phase. Images can be obtained for cations, like calcium and sodium, as well as for phospholipid parent and fragment ions. The phospholipids identified include dipalmitoyl- and palmitoyloleoylphosphatidylcholine as positive ions and dipalmitoyl- and palmitoyloleoylphosphatidylglycerol as negative ions. We observe good miscibility of phospholipids with similar chain lengths but different headgroups. At higher surface pressures, dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol cocrystallize in the liquid condensed (LC) phase. As well, there is evidence of an intermediate phase, within the LC region. The results indicate that the details of phospholipid mixing and reorganization in surfactant films can be determined by static secondary ion mass spectrometry imaging at high resolution, thus providing insight into the relationship between composition and structure in surfactant films at the air−aqueous interface.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.009 | 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".