An in vivo study with 19 rabbits was completed. Half of the exposed rabbits had a magnetic field placed externally over their right lung. Magnetic resonance images of the lungs were acquired to determine the iron concentrations in the right and left lung of each animal. The right/left ratio increased in the middle and basal regions of the lung. With further optimization, this technique could be an effective method for targeted drug delivery. Additionally, the feasibility of increasing the length of high aspect ratio particles for improved targeted drug delivery was explored. An ultrasonic nozzle was pulsed into a large evaporation chamber. Individual particles were found to be double the original length. However, due to locally increased humidity the droplets were not dried, except with the use of an orifice to rapidly accelerate and break apart the larger droplets. The complications associated with this method make it an undesirable and unfeasible method of creating longer particles.

The atmospheric transport of various substances from the continents to the oceans plays an important role in biogeochemical processes. Trace metals, iron in particular is of great interest as its availability regulates the growth of phytoplankton over large areas of the ocean. This dissertation focuses on examining and characterizing the factors that affect the solubility of trace metals in Miami and Barbados aerosols and precipitation, in particular species that could play a role in surface seawater biogeochemistry (Fe and trace metals such as Al, V, Cr, Mn, Cu, Co, Ni, Zn, As, Tl, Ba, Cd, Pb, Th, Ti, Zr, and REE's). To enable this study existing methods of colorimetric spectroscopic and inductively coupled plasma mass spectrometry analysis were improved and modified. This dissertation examines several issues related to source inputs: 1.) Are single spot sources within the North African dust source distinguishable after long transport by their bulk metal composition and thus important in the characteristics of individual mineral dust samples? 2.) What is the temporal variability and controlling factors in trace metal solubility in trade wind aerosols collected over Barbados? 3.) Which factors control the observed trend of speciation and increasing iron solubility in decreasing aerosol loading? Additionally a kinetic model of species specific iron (II) to iron(III) oxidation kinetics in NaCl Brines was conducted at nano-molar levels. This study greatly expands the ability to predict rates of iron oxidation at concentrations closer to those observed in natural systems.

El estudio de los niveles y composición del material particulado atmosférico (PM) medido simultáneamente en diferentes ambientes a escala regional se llevó a cabo en la cuenca del Mediterráneo Occidental con el fin de entender las fuentes y patrones de transformación y transporte de aerosoles en esta zona. Para esto, la medida de niveles y caracterización química de PM10, PM2.5 y PM1 se llevó a cabo en tres estaciones de monitoreo: Montsec (MSC, fondo continental, 1570 msnm), Montseny (MSY, fondo regional, 720 msnm) y Barcelona (BCN, fondo urbano, 68 msnm). Además, se midieron niveles de número de partículas (N) y carbono negro (BC) en BCN. Durante el invierno, la frecuente estabilidad atmosférica induce el estancamiento de masas de aire produciendo importantes episodios de contaminación en BCN. Sin embargo, MSY y, más frecuentemente MSC, quedan aislados de la contaminación regional. En determinados escenarios, el desarrollo de la capa límite y las brisas resultan en el transporte de masas de aire contaminadas a zonas rurales, aumentando notablemente los niveles de PM en función de la altitud y la distancia a las zonas fuente. Durante el verano, la circulación de brisas favorece la dispersión, mezcla y envejecimiento de contaminantes a escala regional y la reducción de las diferencias entre BCN, MSY y MSC. Se midieron niveles similares de algunos componentes (materia orgánica, sulfato) a escala regional. Los niveles de materia mineral aumentan en verano por una resuspensión favorecida y una mayor frecuencia de intrusiones africanas, más significativamente en el MSC, dado su impacto en altura. La mayor contribución al PM10 en BCN se debe principalmente al tráfico (50% del PM10), resultante de las emisiones del tráfico primarias, nitrato y aerosoles secundarios envejecidos. La materia mineral se origina por resuspensión del polvo de carretera por vehículos pero también resuspensión por viento y obras. La contribución regional en BCN (25%) es principalmente materia mineral, nitrato y sulfato amónico. La variabilidad horaria de los diferentes parámetros de medida de aerosoles en BCN (N, BC, PM10, PM2.5 y PM1) está muy marcada por emisiones de tráfico y meteorología (especialmente brisas). Sin embargo, algunos parámetros no se rigen solamente por emisiones directas del tráfico, como PM2.5-10 (resuspensión) y N (emisiones de partículas ultrafinas y procesos de nucleación fotoquímica). La influencia de las emisiones del tráfico en los niveles de partículas finas en BCN se refleja en los niveles anuales de PM1, que aumentan de 2003 a 2007 relacionados con un aumento progresivo del tráfico y la flota diesel en BCN. Sin embargo se observó una tendencia decreciente en las fracciones gruesas en BCN y MSY, que se atribuye a la meteorología y a cambios en emisiones industriales. El estudio simultáneo de diferentes parámetros ha mostrado que el control de PM1 (modos de nucleación y acumulación) y/o BC (procesos de combustión), y PM10, (combustión y aerosoles generados mecánicamente) puede ser una estrategia mejor que la combinación de PM2.5 y PM10 como estándares de medida de calidad del aire. La medida en paralelo de aerosoles en fondos urbano, regional y continental ha sido una estrategia útil para entender la fenomenología de aerosoles en la cuenca del Mediterráneo Occidental. Las emisiones urbanas e industriales tienen un impacto considerable en los niveles y composición de PM en zonas rurales situadas a diferentes alturas, tanto en verano, con una importante recirculación y mezcla de masas de aire a escala regional, como en invierno, con transporte de contaminantes activado por brisas. El gran impacto de la contaminación urbana a escala regional demuestra la importancia de aplicar estrategias de reducción de emisiones de tráfico urbano, a fin de mejorar la calidad del aire no sólo a nivel local, sino también a escala regional. / A detailed study of atmospheric particulate matter (PM) levels and composition measured simultaneously in different environments at a regional scale was performed in the Western Mediterranean Basin in order to understand the sources, transformation and transport of tropospheric aerosols in this area. In this direction, the monitoring of PM10, PM2.5 and PM1 levels and chemical characterization was carried out at three monitoring stations: Montsec (MSC, continental background, 1570 m.a.s.l.), Montseny (MSY, regional background, 720 m.a.s.l.) and Barcelona (BCN, urban background, 68 m.a.s.l.). In addition, number concentration (N) and black carbon (BC) levels were monitored at BCN. During winter, the frequent anticyclonic atmospheric stability induces the stagnation of air masses that produce important pollution episodes at BCN. However, atmospheric decoupling leaves MSY and, more frequently MSC, isolated from regional pollution during several days. In specific scenarios, the growth of the boundary layer and development of mountain breezes, activated by solar radiation, result in the transport of polluted air masses accumulated in the valley to the rural sites, increasing markedly PM levels at a different rate depending on the altitude and distance to the source areas. During summer, intense breeze circulations and atmospheric mixing favour the dispersion, recirculation and ageing of pollutants at a regional scale, reducing the differences between the urban and the rural sites. Similar levels of some components (organic matter or sulphate) were measured at a regional scale. Mineral matter levels increase during the summer, because of a favoured dust resuspension and higher frequency of African dust outbreaks, more significantly at MSC given the impact of African dust at higher altitudes. The major contribution to PM10 in BCN was mainly related to road traffic (50% of PM10), resulting from primary traffic emissions, secondary nitrate and aged secondary aerosols. Anthropogenic dust may originate from road dust resuspension by vehicles, but also wind resuspension and construction/demolition works. The regional contribution at the urban site (25%) was mainly mineral dust, ammonium sulphate and nitrate. The hourly variability of aerosol measurement parameters (N, BC, PM10, PM2.5 and PM1) at BCN is very influenced by road traffic emissions and meteorology (especially breezes). However, some parameters are not only governed by traffic exhaust emissions, as PM2.5-10 (dust resuspension processes) and N (direct ultrafine particle emissions but also photochemical nucleation processes). The influence of road traffic emissions on the levels of fine PM at BCN is reflected in PM1 mean annual levels, showing an increasing trend from 2003 to 2007 and correlation with the progressive rise in road traffic flow and diesel fleet in BCN. However a decreasing trend was observed for the coarser fractions at BCN and MSY, attributed to meteorology and changes in industrial emissions. The simultaneous study of different parameters showed that the monitoring of PM1 (nucleation and accumulation modes) and/or BC (combustion processes), and PM10 (combustion and mechanically-generated aerosols) may be a better strategy than the combination of PM2.5 and PM10 measurements as air quality standards. The parallel monitoring of aerosols at urban, regional and continental backgrounds was a useful strategy in order to understand the phenomenology of aerosols in the WMB. Urban and industrial emissions have a considerable impact in PM levels and composition in rural areas at different altitudes, both in summer, with important atmospheric recirculation and mixing of air masses at a regional scale, and winter, with breeze-activated transport of stagnated urban pollutants. The high contribution of urban emissions and the transport of air masses at a regional scale demonstrate the importance of applying emission abatement strategies for urban road traffic, in order to improve air quality not only at a local, but also at a regional scale.

Background: Evidence on aerosol delivery via tracheostomy is lacking. The purpose of this study was to evaluate the effect of aerosol device and administration technique on drug delivery in a simulated spontaneously breathing pediatric model with tracheostomy. Methods: Delivery efficiencies during spontaneous breathing with assisted and unassisted administration techniques were compared using the jet nebulizer (JN- MicroMist), vibrating mesh nebulizer (VMN- Aeroneb Solo) and pressurized metered-dose inhaler (pMDI- ProAirHFA). The direct administration of aerosols in spontaneously breathing patients (unassisted technique) was compared to administration of aerosol therapy via a manual resuscitation bag (assisted technique) attached to the aerosol delivery device and synchronized with inspiration. An in-vitro lung model consisted of an uncuffed tracheostomy tube (4.5 mmID) was attached to a collecting filter (Respirgard) which was connected to a dual-chamber test lung (TTL) and a ventilator (Hamilton). The breathing parameters of a 2 years-old child were set at an RR of 25 breaths/min, a Vt of 150 mL, a Ti of 0.8 sec and PIF of 20 L/min. Albuterol sulfate was administered with each nebulizer (2.5 mg/3 ml) and pMDI with spacer (4 puffs, 108 µg/puff). Each aerosol device was tested five times with both administration techniques (n=5). Drug collected on the filter was eluted with 0.1 N HCl and analyzed via spectrophotometry. Results: The amount of aerosol deposited in the filter was quantified and expressed as inhaled mass and inhaled mass percent. The pMDI with spacer had the highest inhaled mass percent, while the VMN had the highest inhaled mass. The results of this study also found that JN had the least efficient aerosol device used in this study. The trend of higher deposition with unassisted versus assisted administration of aerosol was not significant (p>0.05). Conclusions: Drug deposited distal to the tracheostomy tube with JN was lesser than either VMN or pMDI. Delivery efficiency was similar with unassisted and assisted aerosol administration technique in this in vitro pediatric model.

The goal of this project was to study the deliquescence kinetics of aerosol particles of atmospheric significance. In the course of this work a novel experimental method was developed, which utilizes the measurement of the water vapor loss in laminar aerosol flow to determine vapor uptake on the aerosol surface. The newly designed flow tube apparatus uses a system of Nafion based dryers and humidifiers, which greatly simplifies the optimization and control of the relative humidity in the aerosol flow. The design, which also utilizes a movable inlet, enables easy variation of the aerosol residence time in the deliquescence reactor, while keeping other experimental conditions constant. In this study, a numerical retrieval procedure was used to characterize aerosols in situ from their IR extinction spectra. The procedure allows that the aerosol size, number distribution, phase and composition be determined, provided the optical constants of all the components (materials) comprising the aerosol are known. For the purpose of studying the deliquescence kinetics of ammonium sulfate aerosol and monitoring their evolution from solid to liquid (state), we have acquired a set of optical constants for a range of (NH4)2SO4 compositions. A set of experiments in a somewhat modified flow tube set up was performed to produce AMS aerosols of known composition, including solid, saturated (water) solution (40 % wt.) and a series of diluted solutions with composition ranging between 40 and 10 % wt. in 5 % increments. The IR spectra of these model aerosols were used to derive the optical constants, using an inversion method proposed by Clapp. The derived refractive indices, which cover the spectral range from 590 to 5990 cm-1 with 2 cm-1 resolution, were compared with those already available in the literature. Using various examples to compare the quality of fittings to experimental spectra, we demonstrated that our optical constants present an improvement relative to those previously reported by B. Toon’s (for crystalline AMS) and S. Martin’s (for AMS solution). The suitability of applying this procedure to ammonium sulfate aerosols and its sensitivity to spectral range was also investigated and discussed. As a preparatory step for the deliquescence kinetics study, our new flow tube apparatus and the tools for the characterization of aerosol were verified in a standard deliquescence experiment performed on (NH4)2SO4 aerosols. The deliquescence process of an equilibrated aerosol flow was monitored as a function of increasing humidity and the deliquescence relative humidity (DRH) determined to be 79.6 ± 0.85 % which is, within experimental uncertainty, in an excellent agreement with the results reported by other research groups. In the kinetic experiment, a flow of solid (NH4)2SO4 aerosols is pre-humidified to a humidity close to, but enough below DRH that there is no detectable amount of liquid aerosols in the system. Such an equilibrated aerosol flow was introduced to the deliquescence reactor where it is further humidified in a controllable manner, by varying the position of the movable inlet. The amount of water transferred to the aerosol through the Nafion membrane was closely monitored, as well as the resulting increase in the water content in the aerosol flow (both gaseous and liquid). This was achieved by measuring the RHs and flow rates of the aerosol and humidification flow, and the characterization of aerosol composition and concentration using their IR spectra. The experimental conditions and aerosol residence times in the reactor where chosen such that no other diluted solution except for saturated (NH4)2SO4 droplets were produced in the process. The number distribution of deliquesced aerosols and the corresponding change in the water content in the aerosol flow were used by a newly developed kinetic model to determine the kinetics of the deliquescence process. Assuming fully developed laminar flow conditions, the water vapor concentration in the flow and its depletion in the presence of aerosol was modeled, to retrieve the value of the water vapor uptake. In the case of micron-sized ammonium sulfate aerosols, which were used in this study, the uptake coefficient,, was determined to be 0.0072 ± 6.54x10-3. The uncertainty associated with this value, as well as the suggested improvements to the experimental procedure and the kinetic model in order to reduce the uncertainty were discussed.

Background: HFNC system is a novel device used with aerosol therapy and seems to be rapidly accepted. Although there are some studies conducted on HFNC and vibrating mesh nebulizer, the effect of HFNC on aerosol delivery using jet nebulizer or pressurized metered-dose inhaler (pMDI) has not been reported. In an effort to examine the effect of HFNC on aerosol deposition, this study was conducted to quantify aerosol drug delivery with or without a HFNC using either pMDI or jet nebulizer. Methodology: The SAINT model, attached to an absolute filter (Respirgard II, Vital Signs Colorado Inc., Englewood, CO, USA) for aerosol collection, was connected to a pediatric breathing simulator (Harvard Apparatus, Model 613, South Natick, MA, USA). To keep the filter and the SAINT model in upright position to collect aerosolized drug, an elbow adapter was connected between the absolute filter and the breathing simulator. An infant HFNC (Optiflow, Fisher & Paykel Healthcare LTD., Auckland, New Zealand) ran at 3 l/min O2 was attached to the nares of the SAINT model. Breathing parameters used in this study were Vt of 100 mL, RR of 30 breaths/min, and I:E ratio of 1: 1.4. Aerosol drug was administered using: 1) Misty-neb jet nebulizer (Allegiance Healthcare, McGaw Park, Illinois, USA) powered by air at 8 l/min using pediatric aerosol facemask (B&F Medical, Allied Healthcare Products, Saint Louis, MO, USA) to deliver albuterol sulfate (2.5 mg/3 mL NS), and 2) Four actuations of Ventolin HFA pMDI (90 μg/puff) (GlaxoSmithKline, Research Triangle Park, NC, USA) combined with VHC (AeroChamber plus with Flow-Vu, Monaghan Medical, Plattsburgh, NY, USA). Aerosol was administered to the model with and without the HFNC and another without (n=3). Drug was collected on an absolute filter, eluted and measured using spectrophotometry. Independent t tests were performed for data analysis. Statistical significance was determined with a p value of <0.05. Results: The mean inhaled mass percent was greatest for pMDI with (p = 0.0001) or without HFNC (p = 0.003). Removing HFNC from the nares before aerosol treatment trended to increase drug delivery with the jet nebulizer (p = 0.024), and increased drug delivery by 6 fold with pMDI (p = 0.003). Conclusions: Aerosol drug may be administered in pediatrics receiving HFNC therapy using either jet nebulizer or pMDI. However, using pMDI, either with or without HFNC, is the best option. When delivering medical aerosol by mask, whether by jet nebulizer or pMDI, removing HFNC led to an increase in inhaled mass percent. However, the benefit of increased aerosol delivery must be weighed against the risk of lung derecruitment when nasal prongs are removed.

The goal of this project was to study the deliquescence kinetics of aerosol particles of atmospheric significance. In the course of this work a novel experimental method was developed, which utilizes the measurement of the water vapor loss in laminar aerosol flow to determine vapor uptake on the aerosol surface. The newly designed flow tube apparatus uses a system of Nafion based dryers and humidifiers, which greatly simplifies the optimization and control of the relative humidity in the aerosol flow. The design, which also utilizes a movable inlet, enables easy variation of the aerosol residence time in the deliquescence reactor, while keeping other experimental conditions constant. In this study, a numerical retrieval procedure was used to characterize aerosols in situ from their IR extinction spectra. The procedure allows that the aerosol size, number distribution, phase and composition be determined, provided the optical constants of all the components (materials) comprising the aerosol are known. For the purpose of studying the deliquescence kinetics of ammonium sulfate aerosol and monitoring their evolution from solid to liquid (state), we have acquired a set of optical constants for a range of (NH4)2SO4 compositions. A set of experiments in a somewhat modified flow tube set up was performed to produce AMS aerosols of known composition, including solid, saturated (water) solution (40 % wt.) and a series of diluted solutions with composition ranging between 40 and 10 % wt. in 5 % increments. The IR spectra of these model aerosols were used to derive the optical constants, using an inversion method proposed by Clapp. The derived refractive indices, which cover the spectral range from 590 to 5990 cm-1 with 2 cm-1 resolution, were compared with those already available in the literature. Using various examples to compare the quality of fittings to experimental spectra, we demonstrated that our optical constants present an improvement relative to those previously reported by B. Toon’s (for crystalline AMS) and S. Martin’s (for AMS solution). The suitability of applying this procedure to ammonium sulfate aerosols and its sensitivity to spectral range was also investigated and discussed. As a preparatory step for the deliquescence kinetics study, our new flow tube apparatus and the tools for the characterization of aerosol were verified in a standard deliquescence experiment performed on (NH4)2SO4 aerosols. The deliquescence process of an equilibrated aerosol flow was monitored as a function of increasing humidity and the deliquescence relative humidity (DRH) determined to be 79.6 ± 0.85 % which is, within experimental uncertainty, in an excellent agreement with the results reported by other research groups. In the kinetic experiment, a flow of solid (NH4)2SO4 aerosols is pre-humidified to a humidity close to, but enough below DRH that there is no detectable amount of liquid aerosols in the system. Such an equilibrated aerosol flow was introduced to the deliquescence reactor where it is further humidified in a controllable manner, by varying the position of the movable inlet. The amount of water transferred to the aerosol through the Nafion membrane was closely monitored, as well as the resulting increase in the water content in the aerosol flow (both gaseous and liquid). This was achieved by measuring the RHs and flow rates of the aerosol and humidification flow, and the characterization of aerosol composition and concentration using their IR spectra. The experimental conditions and aerosol residence times in the reactor where chosen such that no other diluted solution except for saturated (NH4)2SO4 droplets were produced in the process. The number distribution of deliquesced aerosols and the corresponding change in the water content in the aerosol flow were used by a newly developed kinetic model to determine the kinetics of the deliquescence process. Assuming fully developed laminar flow conditions, the water vapor concentration in the flow and its depletion in the presence of aerosol was modeled, to retrieve the value of the water vapor uptake. In the case of micron-sized ammonium sulfate aerosols, which were used in this study, the uptake coefficient,, was determined to be 0.0072 ± 6.54x10-3. The uncertainty associated with this value, as well as the suggested improvements to the experimental procedure and the kinetic model in order to reduce the uncertainty were discussed.

No description available.

Nucleation of ice crystals in the atmosphere often occurs through heterogeneous freezing processes facilitated by an atmospheric aerosol that acts as the ice nuclei (IN). Depending on ambient conditions and aerosol composition, heterogeneous nucleation will occur through one of several mechanisms including the contact and immersion freezing mechanisms. Through a series of contact freezing experiments, we have characterized the ability of aerosols composed of volcanic ash, soot, and peat soil, to act as ice nuclei (IN) as a function of temperature. The immersion freezing ability of the ash particles has also been measured. In these studies, an optical microscope apparatus equipped with a cooling stage and a digital camera was used to observe the freezing events. For each experiment, a particular IN was placed in contact with the surface, or immersed in the bulk, of an ultra pure water droplet. The droplet was then subjected to freezing-melting cycles resulting in 25 independent measurements of the freezing temperature of the droplet. In the volcanic ash experiments, we observed contact freezing at warmer temperatures than immersion freezing. As contact freezing IN, the peat was the most effective with an average contact freezing temperature of -10.5 �C, followed by volcanic ash (-11.2 �C), and then soot (-25.6 �C). In addition, we have used classical nucleation theory to identify the contact parameters and nucleation rates for the compositions explored.

Numerical simulations were performed to study the turbulent mixing of a scalar species in straight tube, single and double elbow flow configurations. Different Reynolds Averaged Navier Stokes (RANS) and Large Eddy Simulation (LES) models were used to model the turbulence in the flow. Conventional and dynamic Smagorinsky sub-grid scale models were used for the LES simulations. Wall functions were used to resolve the near wall boundary layer. These simulations were run with both two-dimensional and three-dimensional geometries. The velocity and tracer gas concentration Coefficient of Variations were compared with experimental results. The results from the LES simulations compared better with experimental results than the results from the RANS simulations. The level of mixing downstream of a S-shaped double elbow was higher than either the single elbow or the U-shaped double elbow due to the presence of counter rotating vortices. Penetration of neutralized and non-neutralized aerosol particles through three different types of tubing was studied. The tubing used included standard PVC pipes, aluminum conduit and flexible vacuum hose. Penetration through the aluminum conduit was unaffected by the presence or absence of charge neutralization, whereas particle penetrations through the PVC pipe and the flexible hosing were affected by the amount of particle charge. The electric field in a space enclosed by a solid conductor is zero. Therefore charged particles within the conducting aluminum conduit do not experience any force due to ambient electric fields, whereas the charged particles within the non-conducting PVC pipe and flexible hose experience forces due to the ambient electric fields. This increases the deposition of charged particles compared to neutralized particles within the 1.5” PVC tube and 1.5” flexible hose. Deposition 2001a (McFarland et al. 2001) software was used to predict the penetration through transport lines. The prediction from the software compared well with experiments for all cases except when charged particles were transported through non-conducting materials. A Stairmand cyclone was designed for filtering out large particles at the entrance of the transport section.