Phase Transitions of Malonic and Oxalic Acid Aerosols
Bibliographic record
Abstract
Atmospheric aerosol has been shown to contain an organic component that includes a significant fraction of small dicarboxylic acids, particularly in the urban environment. As an initial step toward understanding the phase in which particles may exist, a detailed study into the phase transitions of malonic and oxalic acid aerosols has been carried out. Both the aerosol phase transitions (deliquescence and efflorescence) and bulk solution properties (equilibrium water vapor pressure and the solubility and freezing curves of the aqueous solutions) are reported. An aerosol flow tube-FTIR and a static mode chamber-FTIR have been used to identify particulate phase transitions. In the latter the particles can be observed under ice-supersaturated conditions, allowing investigation of behavior at subeutectic temperatures. We report that both malonic and oxalic acid aerosols sustain a substantial level of solute supersaturation before efflorescence occurs, whereas deliquescence occurs at the thermodynamically predicted relative humidity. At room temperature, malonic acid efflorescence is observed at RH = 6% ± 3% and oxalic acid efflorescence occurs at RH ≤ 5%. Malonic acid particles deliquesce between 69% and 91% RH over the temperature range 293−252 K, and for oxalic acid conditions close to 100% RH are required. We report the first observation of the phase transition of oxalic acid between the anhydrous and dihydrate form and discuss our results in the context of recently published data.
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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 | 0.000 |
| 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 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".