No description available.

Although sexual reproductive development is a critical phase in the life cycle of plants, the effects of air pollutants on the processes involved have not been investigated extensively. This thesis describes experiments undertaken to determine the direct effects of short-term exposures to ozone on the reproductive biology of species with contrasting reproductive growth habits, Brassica campestris L., an indeterminate species, and Plantago major L., a more determinate species. Two purpose-designed exposure chambers were constructed, each of which permitted the reproductive structures of up to twelve plants to be isolated from the vegetative parts and exposed simultaneously to ozone-enriched or charcoal-filtered air. The design of these chambers also permitted whole plant exposures. The occurrence of significant decreases in stomatal conductance and the net rate of photosynthesis following exposure to 70 ppb ozone established that the vegetative structures of both B. campestris and P. major were sensitive to ozone. Visible leaf injury also developed in B. campestris, the extent of which varied with the stomatal conductance of plants prior to fumigation and therefore ozone uptake. The growth of B. campestris and P. major was also reduced following 10 and 14 days of exposure respectively to 70 ppb ozone for 7 h d-1. The effects of ozone on growth differed between the four populations of P. major examined in this study. While a single 6 h exposure of the terminal inflorescence of B. campestris to 100 ppb ozone had no significant effect on reproductive development, repeated exposures over four consecutive days increased the abortion of seeds in apical pods and the precocious germination of seeds in older pods. However, the impact on final seed yield was dependent upon the timing of exposure; thus seed yield was significantly reduced following exposure during the early flowering phase, but was unaffected following exposure during the later stages of reproductive development. The compensation for seed losses in more mature plants resulted from their ability to retain naturally aborting seeds in older pods. Nonetheless, single and multiple exposures to ozone both reduced the rate of germination of harvested seeds and multiple exposures affected seed colour. In P. major, exposure of the fIrst spike to 120 ppb ozone for 7 h d-1 during flowering primarily affected seed number per capsule. Both significant increases and decreases in seed number were observed in the four populations examined, and seed number was also affected in spikes which had not been exposed to ozone, indicating the existence of possible compensation mechanisms. Pollen from both species was also shown to be sensitive to a 6 h in vivo exposure to ozone. The complex responses of B. campestris and P. major following direct exposure of the reproductive structures to ozone suggest that factors other than the type of reproductive growth habit are important in determining the extent of ozone damage and the ability of plants to compensate for reproductive site losses.

A dynamic air quality modeling system is presented for use in regions of complex terrain. It consists of two pre-processors and the air quality model. TERRAIN is the terrain analysis preprocessor. It accepts as input digitized terrain elevation data and analyses it in terms of the orientation and steepness of slopes. WIND is the second reprocessor, and based on the results of TERRAIN, determines the area in the region where the wind would be channeled or diverted. It produces a pair of wind matrices for the region of interest which give the horizontal and vertical shifts in direction respectively, at each point in the region at several vertical elevations. Each of the preprocessors are executed once for any particular region. The output from WIND is then read into DAMCT. DAMCT is a dynamic air quality model for regions of complex terrain. It accepts as input the matrics from WIND, a source emissions inventory for the region, and a sequence of meteorological conditions. It produces estimates of pollution concentrations at each point in the region at several vertical elevations over time. This data can then be processed by a general contour plotting program to give graphical displays of the concentration levels. This system is designed to be used for a mesoscale region, but can be applied to any size region be simply adjusting the grid size parameter. DAMCT can be run any number of times desired for a particular region after TERRAIN and WIND have been executed. The user can therefore modify the source inventory to reflect potential changes in the region and get an estimate of the effects. Any set up to 25 different meteorological conditions can be used, representing either typical conditions, or worst case conditions, as desired. The system is intended to provide estimates of pollution concentration for the region of interest while still being relatively simple to execute from the user’s point of view. A user’s guide for each program is also given. / Ph. D.

Kin-Fai Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves [61-66]). / Abstracts in English and Chinese. / Contents / ACKNOWLEDGMENT / ABSTRACT / Chapter CHAPTER 1 --- INTRODUCTION / Chapter 1.1 --- Air Pollution in Hong Kong / Chapter 1.2 --- Brief introduction of Particulate Matter / Chapter 1.2.1 --- Total suspended particulates / Chapter 1.2.2 --- Respirable suspended particulates / Chapter 1.2.3 --- PM2.5 / Chapter 1.3 --- Lead in Air Particulate and its Harmful Effects on Human / Chapter 1.4 --- Air Sampling / Chapter 1.5 --- Sample Treatment / Chapter 1.5.1 --- Acid digestion method / Chapter 1.5.2 --- Slurry sampling method / Chapter 1.5.3 --- Comparison between acid digestion and slurry sampling method / Chapter 1.5.4 --- Chemical modification / Chapter CHAPTER 2 --- EXPERIMENTAL / Chapter 2.1 --- Apparatus / Chapter 2.2 --- Instrumental analysis / Chapter 2.2.1 --- Electrothermal atomic absorption spectrometry / Chapter 2.2.2 --- Background correction by the Zeeman effect / Chapter 2.3 --- Reagents / Chapter 2.4 --- Procedure / Chapter 2.4.1 --- Collection of air sample / Chapter 2.4.2 --- Treatment of sample collected on filter / Chapter 2.4.2.1 --- Digestion Procedure / Chapter 2.4.2.2 --- Procedure for Slurry Preparation / Chapter 2.4.3 --- Temperature program employed / Chapter 2.4.4 --- Sample introduction / Chapter 2.4.5 --- Determination of Lead in PM 2.5 by Acid Digestion Method / Chapter 2.4.6 --- Determination of Lead in PM 2.5 by Developed Method / Chapter 2.4.7 --- Study of particle size and suspension behavior of PM 2.5 in solvent / Chapter CHAPTER 3 --- RESULTS AND DISCUSSION / Chapter 3.1 --- Choice of filter for air sampling / Chapter 3.2 --- Choice of Solvents for Suspension of Air Particulates / Chapter 3.3 --- Ultrasonic agitation / Chapter 3.4 --- Effect of the sonication time / Chapter 3.5 --- Particle size and Effect of stabilization agents / Chapter 3.6 --- Effect of acid predigestion of the slurry sample / Chapter 3.7 --- Chemical Modification / Chapter 3.7.1 --- Use palladium as chemical modifier / Chapter 3.7.2 --- Amount of chemical modifier / Chapter 3.7.3 --- Effect of nitric acid / Chapter 3.8 --- Optimization of the graphite furnace temperature / Chapter 3.9 --- Effect of using platform / Chapter 3.10 --- Sample injection volume / Chapter 3.11 --- Recovery study of Lead in PM2.5 / Chapter 3.12 --- The limit of detection and precision of the developed method / Chapter CHAPTER 4 --- CONCLUSION / APPENDIX / REFERENCES

An online, semi-continuous instrument to measure both total and gas phase atmospheric reactive oxygen species (ROS) and determine the concentration of ROS in the particle phase (ROS(p)) was developed. This instrument was based on a fluorescent probe for quantifying ambient ROS, specifically 2'7'-dichlorodihydrofluorescin, or DCFH probe. This probe was analyzed for sensitivity to a variety of offline and online parameters for efficient use in a field instrument. The ROS(p) instrument measures the peak light intensity at 530 nm to determine ambient ROS concentrations. ROS particles and gases are collected in a mist chamber in a nebulized mist. The instrument alternates measurements of ROS(p+g), or ROS(tot) by means of an inline filter. Fine (PM₂.₅) (ROS(p) is determined by subtraction of the ROS(g) concentration from the ROS(tot), as the ROS(g) signal could not be excluded. This instrument was tested during the summer (May-July) of 2012 at urban and rural sites in the metropolitan Atlanta and surrounding region. Concentrations of ROS(p) determined from this instrument were often below limit of detection. Average concentrations of ROS(p) were found to be 0.25 nmol/m³ in urban Atlanta (Jefferson St. and Georgia Tech), and 0.15 nmol/m³ in Yorkville, a rural site. A side by side comparison of this method with a filter collection method was made in July. The average ROS(p) offline concentrations were 0.15 nmol/m³. These concentrations were comparable to the online average concentrations of 0.21 nmol/m³ for the same period of time. This average and the majority of the measurements comprising it is dominated by the high limit of detection. The ROS instrument as constructed and operated is an efficient way to conduct ROS(p) measurements at the level of a filter study while reducing the labor intensive filter collection and extraction. In order for this instrument to be successful at measuring ambient ROS in the particle phase, the removal of the gas phase from the current sampling scheme is critical as the ROS(g) concentrations are over 90% of the measured ROS. The system as currently operable is best suited for source measurements, including biomass burning plumes or fresh exhaust to capture immediate formation.

This research is intended to serve as an in-depth analysis of air pollution patterns and monitoring networks in the Atlanta area. A ten year database of carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx), ozone (O3), and particulate matter (PM2.5 and PM10) measurements at 17 monitoring stations across the Atlanta area was developed for use in this research. Temporal profiles of air pollutants are analyzed and described. Several factors are identified that impact these profiles, including changes in emissions, meteorology, and photochemistry. Most sites exhibited decreasing annual average concentrations during the study period, with the exception of O3 and NOx, both of which initially increased and then decreased. CO, NOx, and SO2 all have the lowest concentrations in the summer months, while O3 and PM2.5 are highest in the summer months. CO, NOx, and SO2 are also slightly lower on the weekends. CO and NOx have peak daily concentrations at rush hour, while O3 and SO2 peak in the afternoon hours. Instrument error was evaluated through audit and calibration data and collocated data. Collocated data is assumed to be a more accurate representation of instrument error; the percent error calculated using collocated data is much higher than that calculated using audit data. Percent errors were similar for all pollutants using audit and calibration data (2-4%) and were similar for all concentration ranges. Percent errors using collocated data were several times larger. Semivariogram plots are developed to quantify spatial variation of air pollutants. These plots can be interpreted to give the fraction of temporal variation in a pollutant that is actually due to spatial variation. As expected, primary pollutants have higher spatial variation than secondary pollutants. Population weighted averages of the semivariogram function are developed to give a level of uncertainty for a pollutant across the study area. Pollution rose plots are developed to qualitatively examine local sources that are impacting the monitoring sites used in this research. Point sources are easily identified in SO2 plots, as are mobile sources in CO and NOx plots. Pollution roses are also corrected for time of day and season to eliminate false sources.

Experiments were conducted to determine the photocatalytic degradation of three types of gas-phase compounds, NOX, VOCs, and chloramines, by TiO2 impregnated tiles. The oxides of nitrogen NO and NO2 (NOx) have a variety of negative impacts on human and environmental health ranging from serving as key precursors for the respiratory irritant ozone, to forming nitric acid, which is a primary component of acid rain. A flow tube reactor was designed for the experiments that allowed the UV illumination of the tiles under exposure to both NO and NO2 concentrations in simulated ambient air. The reactor was also used to assess NOx degradation for sampled ambient air. The PV values for NO and NO2 were 0.016 cm s-1 and 0.0015 cm s-1, respectively. For ambient experiments a decrease in ambient NOx of ~ 40% was observed over a period of roughly 5 days. The mean PV for NOx for ambient air was 0.016 cm s-1 and the maximum PV was .038 cm s-1. Overall, the results indicate that laboratory conditions generally simulate the efficiency of removing NOx by TiO2 impregnated tiles. Volatile organic compounds (VOC's) are formed in a variety of indoor environments, and can lead to respiratory problems (US EPA, 2010). The experiments determined the photocatalytic degradation of formaldehyde and methanol, two common VOCs, by TiO2 impregnated tiles. The same flow tube reactor used for the previous NOX experiments was used to test a standardized gas-phase concentration of formaldehyde and methanol. The extended UV illumination of the tiles resulted in a 50 % reduction in formaldehyde, and a 68% reduction in methanol. The deposition velocities (or the photocatalytic velocities, PV) were estimated for both VOC's. The PV for formaldehyde was 0.021 cm s-1, and the PV for methanol was 0.026 cm s-1. These PV values are slightly higher than the mean value determined for NO from the previous experiments which was 0.016 cm s-1. The results suggest that the TiO2 tiles could effectively reduce specific VOC levels in indoor environments. Chlorination is a widespread form of water disinfection. However, chlorine can produce unwanted disinfection byproducts when chlorine reacts with nitrogen containing compounds or other organics. The reaction of chlorine with ammonia produces one of three chloramines, (mono-, di-, and tri-chloramine). The production of chloramines compounds in indoor areas increases the likelihood of asthma in pool professionals, competitive swimmers, and children that frequently bath in indoor chlorinated swimming pools (Jacobs, 2007; Nemery, 2002; Zwiener, 2007). A modified flow tube reactor in conjunction with a standardized solution of monochloramine, NH2Cl, determined the photocatalytic reactions over the TiO2 tiles and seven concrete samples. The concrete samples included five different concrete types, and contained either 5 % or 15 % TiO2 by weight. The PV for the tiles was 0.045 cm s-1 for the tiles manufactured by TOTO Inc. The highest PV from the concrete samples was 0.054 cm s-1. Overall the commercial tiles were most efficient at reducing NH2Cl, compared to NOX and VOC compounds. However, the concrete samples had an even higher PV for NH2Cl than the tiles. The reason for this is unknown; however, distinct surface characteristics and a higher concentration of TiO2 in the concrete may have contributed to these findings.

Orientadores: Ricardo Augusto Mazza, Edson Tomaz / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-20T02:12:17Z (GMT). No. of bitstreams: 1 Tadano_YaradeSouza_D.pdf: 4050458 bytes, checksum: f099a0b7346d14abcd5e32043374fc4b (MD5) Previous issue date: 2012 / Resumo: Atualmente os estudos de poluição atmosférica são divididos naqueles que simulam a dispersão dos poluentes e nos que avaliam o impacto da poluição na saúde, não sendo frequentes estudos que envolvem as duas áreas. O objetivo desta pesquisa é propor uma metodologia de união da dispersão com o impacto na saúde, utilizando ferramentas já consolidadas, no intuito de possibilitar avaliações de impacto em regiões que não possuem dados de monitoramento, e ainda a previsão de novos impactos. O estudo foi divido em três partes...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: Currently, air pollution studies are divided in studies that simulate pollutants dispersion and those assessing pollution impacts on health. Studies involving these two areas are not usual. Then, this research aims to present a methodology of union between dispersion and health impact, using tools already consolidated, in order to enable impact assessment in areas that do not have monitoring data and also the prediction of further impacts. This study was divided in three parts...Note: The complete abstract is available with the full electronic document / Doutorado / Termica e Fluidos / Doutor em Engenharia Mecânica

Matched weight polyvinyl chloride (PVC) filters are currently available for use in total dust air sampling. This paper studies the utility of employing two superimposed filters in a cassette. Cassettes containing "paired" PVC filters were employed, in the same way matched weight filters would be used, during side by side sampling studies with cassettes housing single PVC filters, to determine whether the presence of two filters in a cassette presented problems during sampling. The effects of dust type, particle breakthrough, moisture concentration, and increased pressure drop from the addition of a second filter were studied. The presence of static electricity between filter pairs was also noted. Under recommended loading conditions "paired" filters seemed to perform as well as single filters in all aspects studied. Due to large filter weight variations found within individual batches of PVC filters, randomly selected filter pairs should not be used as actual matched weight filters.

The demonstration of antithrombotic efficacy in man is challenging. Most techniques evaluate specific plasma or cellular components under static conditions in vitro. In contrast, in vivo thrombus initiation and growth occur in whole blood, under conditions of continuous flow and in the presence of vascular injury. An in vivo model for use in clinical studies presents significant safety issues and does not currently exist. The Badimon chamber is an ex vivo model of thrombosis that is suitable for use in clinical studies and has previously been used to assess novel antithrombotic regimens. Although well-established, previous characterisation studies were performed in a porcine system and using methodology that has since been superceded. In addition, it has a number of disadvantages that limit its broader applicability and has not previously been used to assess fibrinolysis. Having established The Badimon Chamber within my own institution, I developed the methodology and performed careful validation and characterisation studies with a particular emphasis on reproducibility. These developments allowed more efficient data analysis and the accurate addition of compounds to the extracorporeal circuit, both of which broaden the applicability of the technique. In subsequent studies, using a series of double-blind randomised controlled crossover studies in healthy volunteer cohorts, I utilised the updated methodology to address questions in separate but overlapping areas of cardiovascular medicine. The dynamic regulation of intravascular thrombus formation by the endogenous fibrinolytic system is central to the pathogenesis of acute atherosclerotic events, particularly within the coronary circulation. Previous work within our institution has provided novel insights into the role of endogenous fibrinolysis. Despite a growing body of evidence, a key limitation of studies to date is that the effects of acute endogenous t-PA release on in situ thrombus formation have not been demonstrated. Is endogenous endothelial t-PA released under agonist stimulation functionally active and able to enhance fibrinolysis of in situ thrombus? Firstly, I demonstrated that the addition of exogenous t-PA into the extracorporeal circuit of The Badimon Chamber results in a dose dependent increase in plasma D-dimer associated with a dose dependent reduction in thrombus formation, consistent with enhanced fibrinolysis. Having validated the model, I proceeded to investigate whether freshly released endogenous t-PA would have similar effects to exogenous t-PA. By combining intraarterial infusion of bradykinin into the human forearm in order to stimulate acute release of endogenous t-PA with an assessment of thrombus formation in the Badimon Chamber, I demonstrated that endogenous t-PA released acutely from the human vascular endothelium enhances fibrinolysis and limits in situ thrombus formation. These data validate the forearm model as a relevant model with which to assess acute fibrinolytic capacity, confirm the functional significance of t-PA released during agonist stimulation and suggest that further studies to explore its therapeutic manipulation are warranted. I went on to evaluate a promising small molecule PAI-1 inhibitor, PAI-749, using assessments of ex vivo thrombosis complimented by extensive in vitro studies. Interestingly, in contrast to the promising results seen with this compound in preclinical models, we were unable to demonstrate efficacy in any of the clinical models used, highlighting the potential pitfalls of relying solely on in vitro and preclinical models during early compound development. In the final phase of this work, I used the chamber to explore the prothrombotic effects of exposure to air pollution. A plethora of observational data exist to suggest that acute exposure to particulate air pollution can trigger vascular events including myocardial infarction although the underlying mechanisms are only partly understood. Using a unique human exposure facility, we demonstrated that inhalation of diesel exhaust causes platelet activation and enhances thrombus formation. These data provide a plausible mechanism linking exposure to particulate air pollution with acute cardiovascular events including myocardial infarction. Furthermore, in a separate study we were able to demonstrate that reducing the particulate component of the exposure using a commercially available particle trap prevents the detrimental effects on ex vivo thrombosis and endothelial function. These data support calls for the application of particle traps to diesel-powered vehicles in order to limit a range of adverse cardiovascular effects that result from exposure to traffic-derived air pollution.