Effects of Environmental and Mechanical Variations on Particle Size Distribution of Albuterol HFA Inhalers.

BACKGROUND: The purpose of this study was to evaluate how factors (ambient temperature, shaking the inhaler before use, suspension of the inhaler in water, and the variation over the lifetime of the inhaler) affect the particle-size distributions from albuterol HFA inhalers. METHODS: We used a laser particle-size analyzer to measure the percentage of particles in the 1- to 5-µm range (fine-particle fraction) serially 2,500 times per second to obtain a window of useful measurements with each inhaler actuation. We compared the inhaler performance results as follows: cold versus hot, full versus partial versus empty inhaler actuations, shaken versus unshaken, and inhaler characteristics after water submersion. RESULTS: The effect of temperature was as follows: fine-particle fraction was 14.4% at 5°C, 37.9% at 24 - 25°C, and 38.1% at 45°C. The fine-particle fraction at the start, middle, end, and past the end of the inhaler's rated lifetime were 37.9, 26.3, 27.9, and 22.0%, respectively. Shaking the inhaler did not improve the inhaler's fine-particle fraction. Submerging the inhaler reduced the fine-particle fraction to 14.3% without purging and to 20.5% with purging compared with the 42.1% for the control inhaler, which was not submerged. CONCLUSIONS: Temperature made a difference, with cold inhalers producing a lower fine-particle fraction. The early portion of the inhaler had a better fine-particle fraction than the middle and end of the inhaler's lifespan. We could not demonstrate that shaking the inhaler had a significant effect on the fine-particle fraction. Submerging the inhaler in water significantly reduced the fine-particle fraction.

Shedding from chemically-treated oil droplets rising in seawater.

The degree to which droplet shedding (tip-streaming) can modify the size of rising oil droplets has been a topic of growing interest in relation to subsea dispersant injection. We present an experimental and numerical approach predicting oil droplet shedding, covering a wide range of viscosities and interfacial tensions. Shedding was observed within a specific range of droplet sizes when the oil viscosity is sufficiently high and the IFT is sufficiently low. The affected droplets are observed to reduce in size, as smaller satellite droplets are shed, until the parent droplet reaches a stable size. Shedding of smaller droplets is related to the viscosity-dominated modified capillary number (Ca'), especially for low dispersant dosages recommended for subsea dispersant injection. This, in combination with the IFT-dominated Weber number (We), characterise droplets into three possible states: 1) stable (Ca' < 0.21 &We<12); 2) tip-streaming (Ca' > 0.21 &We<12); 3) unstable and subject to total breakup (We>12).

Toxicity of lanthanum oxide nanoparticles to the fungus Moniliella wahieum Y12T isolated from biodiesel.

Moniliella wahieum Y12T, isolated from biodiesel was used as a model organism to assess the use of lanthanum oxide (La2O3) (60-80 nm) and silver oxide (AgO) (10-40 nm) nanoparticles as potential fungal inhibitors. This is the first study to investigate the use of nanoscale La2O3 as a eukaryotic bio-inhibitor. The AgO nanoparticles were relatively effective at inhibiting the growth of M. wahieum Y12T. The half maximal effective concentration (EC50) for AgO was 0.012 mg/mL as compared with 4.63 mg/mL of La2O3. Fluorescein diacetate analysis showed that AgO nanoparticles significantly reduced metabolic activity in M. wahieum Y12T. The results of this study indicated that AgO nanoparticles can be a nonspecific inhibitor for the treatment of M. wahieum Y12T, a eukaryotic biodiesel contaminant.

Mechanical factors affecting nebulized albuterol aerosol particle sizes for asthma drug delivery.

BACKGROUND: Nebulized particles must have diameters between 1 to 5 µm (optimal particle size range [OPSR]) to be deposited in the lower respiratory tract. The purpose of this study is to determine factors that affect the particle size distributions of nebulized albuterol. METHODS: We used a sophisticated laser diffraction machine to measure aerosol particle size distributions. We compared the percentage of particles in the OPSR at different flow rates through single-use disposable (SUD) and semipermanent nebulizers at different flow rates under different conditions. RESULTS: The SUD nebulizer produced OPSR percentages of 16%, 28%, 40%, 50%, 56%, and 62% at 3, 4, 5, 6, 7, and 8 Liters per minute (Lpm), respectively. The semipermanent nebulizer, however, produced OPSR percentages of 57%, 57%, 60%, and 64% at 3, 4, 5, and 6 Lpm, respectively. The home pump produced a gas flow rate of 5.2 Lpm through the SUD nebulizer and 4.2 Lpm through the semipermanent nebulizer. Single-use disposable nebulizer performance did not degrade with use up to 150 nebulizations. Optimal particle size range percentages did not change significantly with large or small nebulization volumes. CONCLUSION: Single-use disposable nebulizers do not degrade with use, but their performance is highly dependent on gas flow rates. At the flow rate achieved by the home pump, the semipermanent nebulizer performs better than the SUD nebulizer.