AP and vacuum MALDI on a QqLIT instrument
Bibliographic record
Abstract
This article presents a comparative study of the performance, operational, and instrumental characteristics of AP and vacuum MALDI for the analysis of peptides and protein digests. Spectra generated with the two ion sources were surprisingly similar, both qualitatively and quantitatively, with vacuum MALDI generating ion count rates that were approximately a factor of 2 greater than those generated with AP MALDI on this system. Even though the peptide signals were 2X greater with vacuum MALDI, the background intensities also increased by a similar amount, leading to approximately equivalent signal/background ratios for digests and peptide mixtures. The results suggest that when AP MALDI conditions are properly optimized, the sensitivity can approach that of vacuum MALDI. However, AP MALDI performance is critically affected by source gas flows, potentials, and temperature, making it operationally more complex. In addition, evidence is provided for thermal degradation of samples stored on a target plate within a heated AP MALDI ion source. An improved interface for atmosphere to vacuum ion transfer substantially improved these characteristics.
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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 | 0.003 | 0.004 |
| 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 | 0.000 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.009 | 0.004 |
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".