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This thesis presents an overview of the research activities undertaken during my PhD under the supervision of Dr. F. Iza from the School of Electronic, Electrical and Systems Engineering and Dr. B. Buckley from the Chemistry Department at Loughborough University. The thesis is divided as follows. The first chapter of the thesis presents an introduction to plasma and chemical probes as well as the motivation for developing fluorescent probes for plasma characterisation. Analytical techniques used during this work to analyse chemical substances are described in the second chapter. Results and discussions from the experiments are discussed in chapters 3 to 7. Conclusions and future work are presented in chapter 8. In chapter 9, experimental data is presented. In the last century, plasma has attracted the attention of numerous researchers. Due to the wide-range of applications of this ionised gas, people from different fields have focused their effort on studying plasma. Low-temperature plasmas have received growing attention in the last 50 years when the development in cold plasma devices made them more controllable. Plasma played (and continues to play) a critical role in the fabrication process of integrated circuits and recent advances in the generation of low-temperature atmospheric-pressure plasmas have resulted in the emergence of new applications including treatment of temperature sensitive surfaces and biological targets. During the first months at Loughborough I worked on the ozonolysis of various alkenes with air plasmas. This allowed me to familiarised myself with plasma as this was new to me and get a feeling of some of the challenges lying ahead. Nonetheless, the data I obtained was encouraging and I presented the results of batch and flow plasma-based ozonolysis of alkenes at the Technological Plasma Workshop held in Manchester in January 2012. Once I had familiarised myself with the plasma system, I worked on synthesising fluorescent probes to detect ozone, one of the many reactive species that are typically generated in oxygen containing plasmas. Details of the experiments conducted to date and most significant findings are discussed in this thesis.

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Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (doctoral)--Universität Bremen, 2005. / Includes bibliographical references.137-144).

Thesis (Ph. D.)--Oregon Graduate Center, 1978.

This project evaluated the potential for using ozone gas as post-harvest treatment for control of disease in stored potatoes. Ozone is a short-lived, highly reactive oxidizing agent with demonstrated potential to control disease-causing microorganisms. Preliminary trials showed that the atmospheric concentration of ozone obtained using commercial ozone generation equipment depended on the room size and reactive demands in the treatment area. Ozone applied to freshly harvested seed-grade potatoes up to 0-20 mg O3/kg/hr for 1, 7 or 21 days had little significant effect on the incidence or severity of a range of diseases or tuber colour, but did increase tuber weight loss in a dosage-dependant manner. Continuous ozone application (1.9 mg O3/kg/hr) accentuated weight loss by the stored crop. Application of ozone (10-20 mg O3/kg/hr) and Purogene® (Chlorine dioxide; 200 ppm) for 1 day at the mid-point of the winter storage period had no effect on disease levels, skin colour or weight loss measured at the end of storage. When tubers were inoculated with a range of pathogens (Fusarium sambucinum, F. solani., Phytophthora infestans, Helminthosporium solani), introduced at wound depths appropriate to each disease, disease levels typically increased, however ozone treatment (20 mg O3/kg/hr) did not reduce development of any of these diseases. In the absence of potential interference by the surrounding storage environment, pure cultures of Fusarium spp., P. infestans and sclerotia of Sclerotinia sclerotiorum were exposed to 45 mg O3/plate/hr for 1 or 2 days. The ozone treatments had no effect on sporulation of any of the pathogens and did not reduce mycelial growth of Fusarium spp. Mycelial growth of Phytophthora and sclerotial germination of Sclerotinia were suppressed for the duration of the ozone treatment period, however normal growth resumed when the cultures were placed in ozone-free conditions. Ozone treatments (up to 320 mg O3/kg/hr for 2 days) did not reduce the sprouting ability of seed potatoes, however ozone treatments (~20 mg O3/kg/hr for 1, 7 or 21 days) significantly reduced wound periderm thickness of treated potatoes. Treating seed potatoes with ozone (0 or 20 mg O3/kg/hr for 1 or 2 days) prior to planting typically did not affect plant stand or yield, however under cool, wet conditions, ozone-treated seed potatoes produced poorer stands and yields relative to the controls. Based on the results obtained for the range of treatments evaluated in this project, ozone appears to have limited potential as a disease management tool in stored potatoes.

OSIRIS, a Canadian built instrument on-board the Swedish-led remote sensing satellite, Odin, consists in part of three single lens imagers that measure near infrared light from atmospheric scattering and emission. A full calibration of the imaging system is required to remove all instrument dependent effects that modify the observations. <p>This work presents the characterization and calibration of the OSIRIS imaging system in an attempt to produce observations that are instrument independent measurements of the atmospheric brightness. The required product is the number of photons per second emitted, or scattered, from the atmosphere that are within the sampling wavelength range and incident on the detector area in the instrument field of view. <p>A major portion of the present work involves understanding the dark current production mechanisms and the development of a technique to characterize the dark current and manufacturer imposed electronic offsets. It is demonstrated that with a current set of dark calibration images, the developed algorithm effectively removes the dark current and electronic offsets over a wide operating temperature range. The relative calibration of pixels is presented in terms of the electronic gain, or flat field response, and the angular look direction. It is apparent that a change in the relative pixel gain occurred between pre-flight calibration and the first in-flight images. However, it is shown that with a recalculation of the flat field response using in-flight images, an acceptable gain calibration is obtained. The angular look direction of the pixels is determined from the results of two separate in-flight experiments. The characterization and removal of the stray light signal is shown to be effective. <p>Finally, the absolute calibration of the instrument is presented. While several issues remain to be addressed, the comparison with a simple atmospheric brightness model provides a first order verification of the results.

This project evaluated the potential for using ozone gas as post-harvest treatment for control of disease in stored potatoes. Ozone is a short-lived, highly reactive oxidizing agent with demonstrated potential to control disease-causing microorganisms. Preliminary trials showed that the atmospheric concentration of ozone obtained using commercial ozone generation equipment depended on the room size and reactive demands in the treatment area. Ozone applied to freshly harvested seed-grade potatoes up to 0-20 mg O3/kg/hr for 1, 7 or 21 days had little significant effect on the incidence or severity of a range of diseases or tuber colour, but did increase tuber weight loss in a dosage-dependant manner. Continuous ozone application (1.9 mg O3/kg/hr) accentuated weight loss by the stored crop. Application of ozone (10-20 mg O3/kg/hr) and Purogene® (Chlorine dioxide; 200 ppm) for 1 day at the mid-point of the winter storage period had no effect on disease levels, skin colour or weight loss measured at the end of storage. When tubers were inoculated with a range of pathogens (Fusarium sambucinum, F. solani., Phytophthora infestans, Helminthosporium solani), introduced at wound depths appropriate to each disease, disease levels typically increased, however ozone treatment (20 mg O3/kg/hr) did not reduce development of any of these diseases. In the absence of potential interference by the surrounding storage environment, pure cultures of Fusarium spp., P. infestans and sclerotia of Sclerotinia sclerotiorum were exposed to 45 mg O3/plate/hr for 1 or 2 days. The ozone treatments had no effect on sporulation of any of the pathogens and did not reduce mycelial growth of Fusarium spp. Mycelial growth of Phytophthora and sclerotial germination of Sclerotinia were suppressed for the duration of the ozone treatment period, however normal growth resumed when the cultures were placed in ozone-free conditions. Ozone treatments (up to 320 mg O3/kg/hr for 2 days) did not reduce the sprouting ability of seed potatoes, however ozone treatments (~20 mg O3/kg/hr for 1, 7 or 21 days) significantly reduced wound periderm thickness of treated potatoes. Treating seed potatoes with ozone (0 or 20 mg O3/kg/hr for 1 or 2 days) prior to planting typically did not affect plant stand or yield, however under cool, wet conditions, ozone-treated seed potatoes produced poorer stands and yields relative to the controls. Based on the results obtained for the range of treatments evaluated in this project, ozone appears to have limited potential as a disease management tool in stored potatoes.

OSIRIS, a Canadian built instrument on-board the Swedish-led remote sensing satellite, Odin, consists in part of three single lens imagers that measure near infrared light from atmospheric scattering and emission. A full calibration of the imaging system is required to remove all instrument dependent effects that modify the observations. <p>This work presents the characterization and calibration of the OSIRIS imaging system in an attempt to produce observations that are instrument independent measurements of the atmospheric brightness. The required product is the number of photons per second emitted, or scattered, from the atmosphere that are within the sampling wavelength range and incident on the detector area in the instrument field of view. <p>A major portion of the present work involves understanding the dark current production mechanisms and the development of a technique to characterize the dark current and manufacturer imposed electronic offsets. It is demonstrated that with a current set of dark calibration images, the developed algorithm effectively removes the dark current and electronic offsets over a wide operating temperature range. The relative calibration of pixels is presented in terms of the electronic gain, or flat field response, and the angular look direction. It is apparent that a change in the relative pixel gain occurred between pre-flight calibration and the first in-flight images. However, it is shown that with a recalculation of the flat field response using in-flight images, an acceptable gain calibration is obtained. The angular look direction of the pixels is determined from the results of two separate in-flight experiments. The characterization and removal of the stray light signal is shown to be effective. <p>Finally, the absolute calibration of the instrument is presented. While several issues remain to be addressed, the comparison with a simple atmospheric brightness model provides a first order verification of the results.