Viscosity and phase state of aerosol particles consisting of sucrose mixed with inorganic salts
Bibliographic record
Abstract
Research on the viscosity and phase state of aerosol particles is essential because of their significant influence on the particle growth rate, equilibration times, and related evolution of mass concentration as well as heterogeneous reactions. So far, most studies of viscosity and phase state have been focused on organic aerosol particles, yet data on how viscosity can vary when the organic materials are mixed with inorganic salts remain scarce. Herein, using bead-mobility and poke-and-flow techniques, we quantified viscosities at 293 ± 1 K for binary mixtures of organic material / H 2 O and inorganic salts / H 2 O, as well as ternary mixtures of organic material / inorganic salts / H 2 O over the atmospheric relative humidity (RH) range. Sucrose as the organic species and calcium nitrate (Ca(NO 3 ) 2 ) or magnesium nitrate (Mg(NO 3 ) 2 ) as the inorganic salts were examined. For binary sucrose / H 2 O particles, the viscosities gradually increased from ∼ 3 × 10 −2 to ≳ 1 × 10 8 Pa s as RH decreased from ∼ 75 % to ∼ 25 %. Compared with the results for the sucrose / H 2 O particles, binary Ca(NO3)2/H2O and Mg(NO3)2/H2O particles showed drastic enhancements to ≳ 1 × 10 8 Pa s at low RH close to the efflorescence RH. For ternary mixtures of sucrose / Ca(NO 3 ) 2 / H 2 O or sucrose / Mg(NO 3 ) 2 / H 2 O, with organic-to-inorganic mass ratios of 1:1, the viscosities of the particles gradually increased from ∼ 3 × 10 −2 to greater than ∼ 1 × 10 8 Pa s for RH values from ∼ 75 % to ∼ 5 %. Compared to the viscosities of the Ca(NO3)2/H2O particles, higher viscosities were observed for the ternary sucrose / Ca(NO 3 ) 2 / H 2 O particles, with values increased by about 1 order of magnitude at 50 % RH and about 6 orders of magnitude at 35 % RH. Moreover, we applied a thermodynamics-based group-contribution model (AIOMFAC-VISC, Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients Viscosity) to predict aerosol viscosities for the studied systems. The model predictions and viscosity measurements show good agreement within ∼ 1 order of magnitude in viscosity. The viscosity measurements indicate that the studied mixed organic–inorganic particles range in phase state from liquid to semi-solid or even solid across the atmospheric RH range at a temperature of 293 K. These results support our understanding that organic / inorganic / H 2 O particles can exist in a liquid, semisolid, or even a solid state in the troposphere.
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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) | 0.000 | 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".