The Influence of Electrostatic Charge on the Deposition of Therapeutic Aerosols and Airborne Pollutant Particles Within the Human Respiratory System PDF Download
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Author: Adel Hassan Hashish
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Adel Hassan Hashish
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: A. H. Hashish
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Megha Mohan
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Cascade impactors, routinely used for in vitro particle size characterization of pharmaceutical aerosols, are calibrated using dilute, charge-neutralized, monodisperse aerosols. But pharmaceutical aerosols are known to generate concentrated, inherently charged, polydisperse aerosol clouds. A computational model of the Andersen Cascade Impactor (ACI) suggested that the presence of charge on aerosol particles may influence their deposition within the ACI, but experimental validation of the model is warranted. This dissertation investigates the influence of electrostatic charge upon the deposition behavior of aerosols within cascade impactors, to address the impact of charge on particle size characterization. The influence of applied charge upon the deposition pattern and aerodynamic particle size distribution (APSD) of commercially available pressurized metered dose inhalers (pMDIs) within the Electrical Low Pressure Impactor (ELPI) was examined. Electrostatic properties were modified using an external voltage source in conjunction with the ELPI corona charger and observed to be dependent on the formulation and device packaging. Induced artificial charge on the aerosol particles influenced the deposition pattern within the impactor, but did not result in a significant change in the apparent APSD. An experimental apparatus capable of producing charge neutralized and charged aerosol, with targeted deposition on the CFD predicted "charge sensitive" ACI stages, was developed. In vitro results were observed to be in partial agreement with the CFD predictions. While charge influenced the deposition pattern in the ACI with increased deposition observed in the charger and on the upper stages of the ACI, it did not influence the apparent APSD of the aerosol. Electrostatic charge effects on deposition behavior within cascade impactors were delineated with respect to space charge and image charge effects by investigating the influence of impactor grounding, particle size, stage coating and loading. While the deposition pattern within the ACI was influenced by charge, only stage coating and stage loading resulted in a small, significant difference in the apparent APSD, which may not be practically relevant due to the variability associated with in vitro aerosol testing. Similar trends were observed in the deposition behavior of charge neutralized and charged aerosol within an abbreviated ACI system compared to the full resolution ACI.
Author:
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Category : Dissertations, Academic
Languages : en
Pages : 762
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Author:
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Category : Radiation
Languages : en
Pages : 436
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Author:
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Category : Air
Languages : en
Pages : 662
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Author: H.P. Witschi
Publisher: Springer Science & Business Media
ISBN: 3642695213
Category : Medical
Languages : en
Pages : 559
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This book deals with the methods and scientific basis of inhalation toxicology. It describes devices and facilities needed to expose animals to inhaled particles and gases as well as approaches to estimating or measuring the fraction of the inhaled material that is retained in the respiratory tract. The book then reviews the evergrowing repertoire of techniques that can be used to measure the responses elicited by the exposure. Quantitative and qualitative anatomical, physiological, and biochemical strategies are discussed in detail. We believe that the toxicology of inhaled materials is an important and timely topic for several'reasons. During the past decade, morbidity and mortality attributable to cardiovascular disease have significantly decreased. Progress in combatting cancer, the second most important cause of death, has been slower, and lung cancer actually became the leading cause of death in men and the second leading cause of cancer death in women. In addition, the incidence of non-neo plastic respiratory diseases such as emphysema, fibrosis, and chronic bronchitis has increased the past decade. In the United States, the National Institutes of Health (NIH) has recently reported that chronic obstructive pulmonary disease affects nearly 10 miliion persons and accounts for 59,000 deaths yearly; indeed, it ranks as the fifth leading cause of death. Because the incidence is increasing, the NIH estimates that it may become the nation's fourth or even third leading cause of death by the year 2000.
Author: Samir C. Vinchurkar
Publisher:
ISBN:
Category : Aerosol therapy
Languages : en
Pages : 470
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The dynamics of particle laden flows are integral to the analysis of toxic particle deposition and medical respiratory aerosol delivery. Computational fluid-particle dynamics (CFPD) can play a critical role in developing a better understanding of particle laden flows, especially in a number of under-explored areas. The applications considered in this study include both the numerical aspects and the physical phenomena of respiratory aerosol transport. Objective I: Considering the effects of mesh type and grid convergence, four commonly implemented mesh styles were applied to a double bifurcation respiratory geometry and tested for flow patterns and aerosol deposition. Results indicated that the mesh style employed had a significant effect on the transport and deposition of aerosols with hexahedral meshes being most accurate. Objective II: In order to evaluate the effects of bronchoconstriction under exhalation conditions, normal and constricted pediatric airway models were considered. Results include (i) a significant increase in deposition for constricted airways, and (ii) a novel correlation for deposition during exhalation based on the Dean and Stokes numbers. Objective IIIa: Considering evaluation of an aerosol size sampler, an eight-stage Andersen cascade impactor (ACI) was numerically analyzed. The numerical simulations indicated high non-uniformity and recirculation in the flow field. Numerical predictions of retention fraction matched well with existing experiments (0.5 - 11% error). Objective IIIb: As an extension to this study, numerical predictions of electrostatic charge effects on aerosol transport and deposition in the ACI were presented. Charges consistent with standard pharmaceutical pressurized metered dose inhalers and dry powder inhalers were considered. The numerical predictions indicated that charged aerosols deposit as if they were 5 - 85% larger due to electrostatic effects. Applications of the studies considered include (i) quantitative guidance in selecting numerical mesh styles and development of standard grid convergence criteria, (ii) the development of more accurate whole-lung deposition models that better evaluate exhalation conditions, (iii) improvements in the design of pharmaceutical assessment and delivery devices, and (vi) correction values to account for electrostatic charge on pharmaceutical aerosols.
Author: James Mcgrath
Publisher: Elsevier
ISBN: 0323138500
Category : Science
Languages : en
Pages : 368
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Air Pollution—Physiological Effects focuses on the physiological effects of air pollution and reviews research findings concerning physiological responses to air pollutants such as oxidant gases, sulfur dioxide, carbon monoxide, and particulates. Topics range from cellular cytotoxicity and lung infections to carbon monoxide toxicity, deposition of aerosols to the respiratory airway, physiological effects of cotton dusts and lead dusts, and workers' exposure to dust at high altitude. This book is organized in three sections and is comprised of 11 chapters. The discussion begins with an overview of cellular cytotoxicity and the biochemical basis of oxidative cell killing. The reader is methodically introduced to the effects of minute concentrations of pollutants on animal respiratory defenses, air pollution by sulfur products, and mechanisms of carbon monoxide toxicity. Consideration is also given to alterations in airway mechanics that occur with exposures to ozone, nitrogen dioxide, and sulfur dioxide, as well as the mechanisms that might be responsible for these changes in breathing mechanics. The rest of the book discusses both particulate (silica, diesel, cotton, and lead dusts) pollution and the special physiological problems posed by working at high altitudes in dusty environments. This book will be useful not only to environmental health scientists but also to students and researchers in areas peripheral to environmental physiology.
Author:
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ISBN:
Category : Medicine
Languages : en
Pages : 1436
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