Large uncertainties remain in estimating the anthropogenic fraction of mineral dust and the climatic impact of dust aerosol, partly due to a poor understanding of the dust source dynamics under the influence of climate variability and human-induced land-cover/land-use change (LCLUC). So far, the dust dynamics and linkage to climate and LCLUC in Central Asia have received little attention from the aerosol research community. This thesis comprises a comprehensive study of the dust dynamics in Central Asia focusing on 1) the seasonality of erosion threshold and dust emission affected by soil moisture, vegetation phenology and surface roughness, 2) the dust interannual variability and connections with large-scale climate variation (ENSO) through effects on the atmospheric circulation, precipitation, vegetation dynamics and drought, and 3) the impact of dust aerosol on surface radiative balance and photosynthetically active radiation, and possible effect on dryland ecosystems. A coupled dust model and multi-year ground and satellite observations of dust frequency, dust loading, and atmospheric and land conditions are used in this study. We find the threshold friction velocity significantly varies in space and time in response to soil moisture seasonality, surface roughness heterogeneity and vegetation phenology. Spring is associated a higher threshold friction velocity than summer, due to wetter soils and more vegetation cover. As a result, although more frequent strong winds occur during spring, spring dust emission is less than summer by 46.8% (or 60.4 Mt). Ignoring the dependence of the threshold friction velocity on the surface characteristics leads to biased spatial distribution and seasonality of dust emission. There is a strong linkage between dust and ENSO in Central Asia: La Nina years produce drought condition and enhance the dust activity. A decline in the strong wind frequency during 1999−2012 results in a decreasing trend in the modeled dust emission, at a rate of -7.81±2.73 Mt yr-1, as well as a decreasing trend in the ground observed dust frequency index, at a rate of -0.14±0.04%. We estimate that 58.4% of dust emission is caused by human activity during the 1999−2012 period. Our estimates suggest human plays an important role in the region’s dust budget through agriculture and water resource usage.

Primary barriers to drug delivery include mucus and biofilms, which can hinder drug and gene delivery by several orders of magnitude, preventing effective therapeutic effects. By understanding the physical and chemical properties of these ubiquitous barriers, one may employ drug delivery approaches, such as design of nanoparticle and microparticle systems, to attempt to overcome the transport barriers. Nanoparticles are a growing interest in drug delivery, specifically as drug carriers, though most will become entrapped within these extracellular barriers further limiting their desired affects. Previous studies have generally manipulated the surface chemistries or size of these nanoparticles to allow for nearly a 2-fold increase in passive diffusion through barriers. To expand the current ideas of overcoming these barriers, studies in presented in this dissertation were performed using a type of active nanoparticle, superparamagnetic iron oxide nanoparticles. It was first investigated whether these particles would disrupt extracellular barriers under an oscillating magnetic field, which resulted in a 2-fold increased diffusion of particles upon biopolymer breakage. Secondly, influences of an external static magnetic field on diffusion of these nanoparticles through model barriers were determined. Both of these methods resulted in higher fold increases, reaching up to 28-fold compared to 2-fold as described in the literature. Next an examination of drug permeation enhancement in models of extracellular barriers by nanoparticle interactions was performed, using a passive mechanism as found in the literature. With a range of different nanoparticles including diesel particulate matter, barrier function was disrupted resulting in a 5-fold increase in drug permeation. To further manipulate drug diffusion an assisted delivery systems was observed, where magnetic nanoparticles could influence un-associated drug diffusion, resulting in 4-fold increase in drug diffusion. Finally formulations of nanosuspensions were created for aerosol delivery and their performance evaluated in vitro. A dry powder formulation containing drug and nanoparticles was formulated using a spray-drying technique. Upon barrier deposition studies using the dry powder formulation, permeation rates were determined resulting in a 2-fold increase for nanoparticle permeation. When drug diffusion was determined up to a 54-fold increase in drug was seen when co-delivered with nanoparticles, compared to controls containing only drug. / text

We have studied a continuous aerosol process for producing oxide nanoparticles with sizes of 10-60 nm that are decorated with smaller 1-3 nm metallic nanoparticles. Such particles may be useful in a number of areas including catalysis and as contrast enhancement agents in biomarkers. To produce the oxide nanoparticle carriers, an aerosol of 1-10 [micrometer] oxide particles are ablated using an excimer laser. The resulting oxide nanoparticle aerosol is then mixed with 1-2 [micrometer] metallic particles and this mixed aerosol is ablated a second time. The oxide nanoparticles are too small to ablate but act as seeds for the nucleation of metallic nanoparticles on the surface of the oxide. The nanoparticle sizes can be varied by changing the gas type or gas pressure in the aerosol. We demonstrate the feasibility of such an approach using two oxides, SiO₂ and TiO₂, and two metals, Au and Ag. / text

The purpose of following project is to study the effect of dust aerosols on the radiative forcing which is directly related to the surface temperature. A single column radiative convective model is used for simulation purpose. A series of simulations have been performed by varying the amount of dust aerosols present in the atmosphere to study the trends in ground temperature, heating rate and radiative forcing for both its longwave and shortwave components. A case study for dust storm is also performed as dust storms are common in Arabian Peninsula. A sensitivity analyses is also performed to study the relationship of surface temperature minimum and maximum against aerosol concentration, single scattering albedo and asymmetry factor. These analyses are performed to get more insight into the role of dust aerosols on radiative forcing.

No description available.

A recently mandated change in the use of pharmaceutical propellants spurred the development and reevaluation of aerosolized pharmaceuticals. Chlorofluorocarbon (CFC) propellants were commonly used in pressurized metered dose inhalers (MDIs), but were unfortunately linked to the depletion of the ozone layer. As such, a search for new propellants was initiated and ultimately resulted in the implementation of hydrofluoroalkane (HFA) propellants in MDIs. These HFA propellants however demonstrated significantly different properties than CFCs and necessitated a considerable amount of reformulation efforts. Not only did HFAs demonstrate different physiochemical properties, but in some cases these differences necessitated reengineering of the delivery device. Unfortunately HFA propellants are considered greenhouse gasses, albeit to a lesser degree than CFCs, so the development of alternate delivery methods has been ongoing. One delivery method that has received significant attention and resources is dry powder inhalers (DPIs). DPIs are a propellant-free alternative to aerosolized drug delivery, and demonstrate some advantages and disadvantages compared to the use of MDIs and nebulizers.In addition to the modernization of pharmaceutical agents, excipients, and delivery devices, technological advances have allowed for different and/or improved characterization of pharmaceutical aerosols. Particle size characteristics of aerosols are the primary physical measure examined and are relevant to ensure proper and reproducible drug delivery to the lung. Likewise, chemical analysis of the pharmaceutical agent is extremely important for pharmaceutical development and monitoring, including solubility determination, stability monitoring, and ultimately, dose emitted. Because many limitations exist in characterization however, and because experimental means can be costly with regard to labor and materials, prediction of aerosol performance characteristics based on formulation and device variables are valuable.Previous work predicting the performance of solution based MDIs has opened the door for improved prediction of suspension based MDI systems. Suspension aerosol prediction has been examined in the past, but additional information is now available to more appropriately model suspension MDI systems that include polydisperse drug material and emit polydisperse droplets.

The Earth’s atmosphere is a vulnerable system which is easily changed by micro- and macrophysical variations. Big decreases in pollution levels of sulfur dioxide over Central Europe from 1980s to 2000s led to decreased mass concentration of atmospheric solid and liquid particles. This gives the opportunity to investigate how these particles influence the atmosphere. Newly released satellite climatology data was used to analyze statistics of cloud properties during four years in the high polluted atmosphere (1985-88) and four years in the less polluted atmosphere (2004-07). These two periods were investigated in collaboration with Atmospheric Remote Sensing Unit of the research department of the Swedish Meteorological and Hydrological Institute (SMHI). Cloud top temperature of liquid clouds over polluted regions during the earlier period was colder by more than 2 K and more than 5 K for only optical thin liquid clouds. The changes in mass concentrations of atmospheric particles derived by the sulfur dioxide emissions are shown to be a highly possible factor to the observed cloud changes. / Jordens atmosfär är ett känsligt system som lätt förändras av mikro- samt makrofysikaliska variationer. Stora minskningar i föroreningsnivåer av svaveldioxid över centrala Europa från 1980 till 2000-talet ledde till minskade masskoncentrationer av fasta och flytande atmosfäriska partiklar. Detta ger en möjlighet att undersöka hur dessa partiklar påverkar atmosfären. Nyligen utvecklad klimatologisk satellitdata användes för att analysera statistik av molnegenskaper under fyra år i en högt förorenad atmosfär (1985-88) och fyra år i en mindre förorenad atmosfär (2004-07). De två perioderna undersöktes i samarbete med Enheten för atmosfärisk fjärranalys av forskningsavdelningen till Sveriges meteorologiska och hydrologiska institut (SMHI). Molntopptemperaturen för moln i vätskefas över förorenande områden under den tidigare perioden var mer än 2 K kallare och mer än 5 K kallare för endast optiskt tunna moln i vätskefas. Förändringarna i masskoncentrationer för atmosfäriska partiklar och droppar med svaveldioxidusläpp som ursprung visas vara högst möjliga att ligga bakom de observerade molnförändringarna.

Atmospheric particles play a crucial role in climate, visibility, air pollution, and human health. Reactions between gas-phase molecules and particles (heterogeneous reactions) affect not only the particle composition and morphology, but also the composition of the atmosphere. This thesis investigates the heterogeneous chemistry of organic mixtures and inorganic solutions coated with organic monolayers as proxies for atmospheric particles. The first topic of interest was the reaction between N₂0₅ and aqueous inorganic solutions coated with organic monolayers. The goal of this work was to better understand how organic monolayers on aqueous particles affect the mass transport and kinetics of N₂0₅ uptake by aqueous aerosols, and consequently what effectthe monolayer can have on predicted concentrations of N₂0₅ in the atmosphere. To investigate heterogeneous reactions of inorganic solutions coated with an organic monolayer a new rectangular channel flow reactor was developed. This newly developed flow reactor was described in detail and validated. Subsequently, the new flow reactor was used to study the reactive uptake of N₂0₅ on sulfuric acid solutions in the presence of a variety of 1- and 2-component monolayers with varying functional groups, solubilities, chain lengths, surface pressures, and molecular surface areas. Reactive uptake of N₂0₅ on aqueous sulfuric acid solutions was found to correlate most strongly with the molecular surface area or packing density of the monolayer. These results provide a good foundation for determining the influence of monolayers on heterogeneous reactions in the atmosphere, and highlight the need for characterization of monolayer surface properties of organic monolayers present on atmospheric particles. The second topic of interest was reactions between 0₃ and proxies for meat cooking aerosols with the goal to better understand the effect of the phase and microstructure of the mixtures on the lifetime of oleic acid (OA) in atmospheric particles. The reactive uptake of 0₃ was approximately 1 order of magnitude slower on binarysolid-liquid mixtures and multicomponent mixtures that closely represent compositions of meat-cooking aerosols compared to the liquid solutions. Lifetimes up to 75 min were obtained for these mixtures.

A new portable flow tube technique, the Toronto Photo-Oxidation Tube v2.0 was developed and characterized to explore its potential to control and monitor the OH-initiated formation and chemical aging of secondary organic aerosol (SOA) in-situ. The first study investigated the different operational parameters of this flow tube technique. TPOT v2.0 can generate oxidizing conditions equivalent to ambient OH exposures of 2.3 – 10.8 days. The transmission efficiency of a model organic aerosol indicated negligible losses in the oxidation tube. Differences in the residence time distribution curves measured for a gas and model organic aerosol showed that particles were subjected to approximately half of the OH exposure compared to gases. The second study examined the capacity of the TPOT technique to generate secondary aerosols due to OH oxidation. High aerosol yield was observed for H2SO4 particles, whereas a low aerosol yield was observed for α-pinene SOA.

A new portable flow tube technique, the Toronto Photo-Oxidation Tube v2.0 was developed and characterized to explore its potential to control and monitor the OH-initiated formation and chemical aging of secondary organic aerosol (SOA) in-situ. The first study investigated the different operational parameters of this flow tube technique. TPOT v2.0 can generate oxidizing conditions equivalent to ambient OH exposures of 2.3 – 10.8 days. The transmission efficiency of a model organic aerosol indicated negligible losses in the oxidation tube. Differences in the residence time distribution curves measured for a gas and model organic aerosol showed that particles were subjected to approximately half of the OH exposure compared to gases. The second study examined the capacity of the TPOT technique to generate secondary aerosols due to OH oxidation. High aerosol yield was observed for H2SO4 particles, whereas a low aerosol yield was observed for α-pinene SOA.