Bibliographic record
Abstract
With the enforcement of the Montreal Protocol on ozone depleting gases, non-ozone depleting hydrofluoroalkanes (HFAs), i.e. HFA-134a and HFA-227ea, are now replacing the ozone depleting chlorofluorocarbon (CFC) propellants in pressurized metered-dose inhalers (pMDIs). The transition has proven to be difficult due to differences in the physical and chemical properties, e.g. higher polarity and higher vapour pressure. Since commonly used surfactants in CFC pMDIs, i.e. Span 85, oleic acid and lecithin are effectively insoluble in HFAs, a surfactant solubility study was carried out in this work in order to find HFA soluble surfactants. Further on, surfactant solubility in HFA-134a and HFA-227ea was compared with those in 2H,3H-decafluoropentane in order assess the latters suitability as a model propellant. This was followed by UV/VIS and fluorescence spectroscopic investigations into surfactant aggregation and aggregate orientation in HFA propellants. Beclomethasone dipropionate (BDP) nanoparticles were formulated from an emulsion template and dispersed in HFA-227ea with the aim of improving pulmonary drug deposition efficiency and drug targeting to smaller airways. In vitro drug deposition profiles of BDP nanoparticle suspension pMDIs were determined using Andersen Cascade impaction and compared to a commercially available BDP suspension CFC pMDI (Becotide) and a BDP solution phase HFA pMDI (Qvar). Furthermore, the stability of BDP nanoparticle suspension pMDIs at elevated conditions was assessed. Soluble surfactants could be found among the polyoxyethylene-ethers and poly (ethylene oxide)-poly (propylene oxide) block copolymers. 2H,3H-decafluoropentane has proven to be a good model propellant for HFA-134a only. The investigations into surfactant behaviour in HFA propellants suggests a stepwise aggregation of L1 orientated surfactant aggregates. Depending on formulation variables, e.g. drug concentration, surfactant concentration and the addition of cosolvent, an improved drug deposition profile compared to the microparticle CFC pMDI was shown for BDP nanoparticle pMDIs. The addition of polyvinylpyrrolidone (PVP) to the nanoparticle suspension proved to reduce particle growth, thus improved pMDI stability.
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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 | 0.001 |
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".