Simultaneous Analysis of the Equilibrium Hygroscopicity and Water Transport Kinetics of Liquid Aerosol

Davies, James F.; Haddrell, Allen E.; Rickards, Andrew M. J.; Reid, Jonathan P.

doi:10.1021/ac4005502

Cited by 52 publications

(85 citation statements)

References 45 publications

(83 reference statements)

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“…The experimental RH was determined as previously discussed [Davies et al, 2013a] using a sodium chloride probe droplet evaporating into a fixed relative humidity and known temperature. The initial size and concentration of the droplets are known, and the final equilibrated size is used to determine a growth factor.…”

Section: The Vapor Pressure Of Watermentioning

confidence: 94%

Temperature dependence of the vapor pressure and evaporation coefficient of supercooled water

Davies

Miles

Haddrell

et al. 2014

J. Geophys. Res. Atmos.

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We report measurements of the vapor pressure of water over the supercooled temperature range 248 to 273 K derived from evaporation kinetics measurements of single water droplets. Accurate measurements of the relative humidity of the surrounding gas phase are derived from comparative and sequential measurements of the evaporation kinetics of droplets containing sodium chloride. The temperature dependence of the vapor pressure of supercooled water is shown to conform closely to the parameterization provided by Murphy and Koop (2005) once the uncertainties in experimental and thermophysical parameters are accounted for by ensuring an accurate representation of evaporation rates at temperatures above 273 K. Further, from a sensitivity analysis of all of the data over the full temperature range from 248 to 293 K, we can conclude that the evaporation coefficient of water, and thus the mass accommodation coefficient, is greater than, or equal to, 0.5.

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Section: The Vapor Pressure Of Watermentioning

confidence: 94%

Temperature dependence of the vapor pressure and evaporation coefficient of supercooled water

Davies

Miles

Haddrell

et al. 2014

J. Geophys. Res. Atmos.

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“…In most of the model simulations the organic compounds are represented by a one-dimensional volatility basis set (Donahue et al, 2006) (1D-VBS, hereafter VBS). Organic compounds are grouped into distinct "bins" in a VBS, described by their saturation (mass) concentration (C sat ) value and the amount of that bin in the gas and particle phases.…”

Section: Process Modelsmentioning

confidence: 99%

Optimization of process models for determining volatility distribution and viscosity of organic aerosols from isothermal particle evaporation data

et al. 2019

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The composition of organic aerosol under different ambient conditions as well as their phase state have been a subject of intense study in recent years. One way to study particle properties is to measure the particle size shrinkage in a diluted environment at isothermal conditions. From these measurements it is possible to separate the fraction of lowvolatility compounds from high-volatility compounds. In this work, we analyse and evaluate a method for obtaining particle composition and viscosity from measurements using process models coupled with input optimization algorithms. Two optimization methods, the Monte Carlo genetic algorithm and Bayesian inference, are used together with process models describing the dynamics of particle evaporation. The process model optimization scheme in inferring particle composition in a volatility-basis-set sense and compositiondependent particle viscosity is tested with artificially generated data sets and real experimental data. Optimizing model input so that the output matches these data yields a good match for the estimated quantities. Both optimization methods give equally good results when they are used to estimate particle composition to artificially test data. The timescale of the experiments and the initial particle size are found to be important in defining the range of values that can be identified for the properties from the optimization.

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“…Here, we report the hygroscopic properties of various pharmaceutical aerosols measured using a single particle analysis technique termed the comparative kinetic electrodynamic balance (CK-EDB). A detailed explanation of this technology has been reported previously (Rovelli et al, 2016;Davies et al, 2013), and only a brief description will be given here (Fig. 3).…”

Section: Measuring the Hygroscopic Growth Dynamics Of Pharmaceuticalmentioning

confidence: 99%

“…The phase function is measured at a frequency of 100 Hz until the droplet reaches an equilibrium with the RH of the airflow, achieving a steady aqueous liquid droplet size. Through sequentially trapping droplets originating from the two dispensers, accurate estimations of the water activity of the airflow that the pharmaceutical containing droplet evaporates into can be inferred by the mass flux from the water droplet (Davies et al, 2013).…”

Section: Measuring the Hygroscopic Growth Dynamics Of Pharmaceuticalmentioning

confidence: 99%

Experimental and computational study of the effect of breath-actuated mechanism built in the NEXThaler® dry powder inhaler

Farkas

Lewis

Church

et al. 2017

International Journal of Pharmaceutics

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Link to publication record in Explore Bristol Research PDF-document This is the final published version of the article (version of record). It first appeared online via Elsevier at https://www.sciencedirect.com/science/article/pii/S0378517317309237 . Please refer to any applicable terms of use of the publisher. University of Bristol -Explore Bristol Research General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms A B S T R A C TThe breath-actuated mechanism (BAM) is a mechanical unit included in NEXThaler ® with the role of delaying the emission of the drug until the inhalation flow rate of the patient is sufficiently high to detach the drug particles from their carriers.The main objective of this work was to analyse the effect of the presence of BAM on the size distribution of the emitted drug and its airway deposition efficiency and distribution. Study of the hygroscopic growth of the emitted drug particles and its effect on the deposition was another goal of this study.Size distributions of Foster ® NEXThaler ® drug particles emitted by dry powder inhalers with and without BAM have been measured by a Next Generation Impactor. Three characteristic inhalation profiles of asthmatic patients (low, moderate and high flow rates) were used for both experimental and modelling purposes. Particle hygroscopic growth was determined by a new method, where experimental measurements are combined with simulations. Upper airway and lung deposition fractions were computed assuming 5 s and 10 s breath-hold times.By the inclusion of BAM the fine particle fraction of the steroid component increased from 24 to 30% to 47-51%, while that of bronchodilator from 25-34% to 52-55%. The predicted upper airway steroid and bronchodilator doses decreased from about 60% to 35-40% due to BAM. At the same time, predicted lung doses increased from about 20%-35% (steroid) and from 22% to 38% (bronchodilator) for the moderate flow profile and from about 25% to 40% (steroid) and from 29% to 47% (bronchodilator) for the high inhalation flow profile. Although BDP and FF upper airway doses decreased by a factor of about two when BAM was present, lung doses of both components were about the same in the BAM and no-BAM configurations at the weakest flow profile. However, lung dose increased by 2-3% even for this profile when hygroscopic growth was taken into account.In conclusion, the NEXThaler ® BAM mechanism is a unique feature enabling high emitted fine particle fraction and enhanced drug delivery to the lungs.

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Simultaneous Analysis of the Equilibrium Hygroscopicity and Water Transport Kinetics of Liquid Aerosol

Cited by 52 publications

References 45 publications

Temperature dependence of the vapor pressure and evaporation coefficient of supercooled water

Temperature dependence of the vapor pressure and evaporation coefficient of supercooled water

Optimization of process models for determining volatility distribution and viscosity of organic aerosols from isothermal particle evaporation data

Experimental and computational study of the effect of breath-actuated mechanism built in the NEXThaler® dry powder inhaler

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