Leung, Tsz Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 132-146). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.vii / List of Figures --- p.xii / List of Plates --- p.xiv / List of Tables --- p.xvii / Abbreviations --- p.xviii / Equations --- p.xxi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Water crisis and water disinfection --- p.1 / Chapter 1.2 --- Common disinfection methods --- p.2 / Chapter 1.2.1 --- Chlorination --- p.2 / Chapter 1.2.2 --- Ozonation --- p.4 / Chapter 1.2.3 --- Ultraviolet-C (UV-C) irradiation --- p.6 / Chapter 1.2.4 --- Solar disinfection (SODIS) --- p.7 / Chapter 1.2.5 --- Mixed disinfectants --- p.9 / Chapter 1.2.6 --- Other disinfection methods --- p.10 / Chapter 1.3 --- Advanced oxidation processes (AOPs) --- p.11 / Chapter 1.4 --- Photocatalytic oxidation (PCO) --- p.13 / Chapter 1.4.1 --- Understanding of PCO process --- p.15 / Chapter 1.4.2 --- Proposed disinfection mechanism of PCO --- p.18 / Chapter 1.4.3 --- Titanium dioxide (Ti02) photocatalyst --- p.21 / Chapter 1.4.4 --- Irradiation sources --- p.22 / Chapter 1.4.5 --- Bacterial species --- p.23 / Chapter 1.4.5.1 --- Escherichia coli K12 --- p.23 / Chapter 1.4.5.2 --- Shigella sonnei --- p.24 / Chapter 1.4.5.3 --- Alteromonas alvinellae --- p.25 / Chapter 1.4.5.4 --- Photobacterium phosphoreum --- p.26 / Chapter 1.4.6 --- Bacterial defense mechanism towards oxidative stress --- p.27 / Chapter 1.4.6.1 --- Superoxide dismutase (SOD) activity --- p.28 / Chapter 1.4.6.2 --- Catalase (CAT) activity --- p.29 / Chapter 1.4.6.3 --- Fatty acid (FA) profile --- p.30 / Chapter 1.4.7 --- Significance of the project --- p.31 / Chapter 2. --- Objectives --- p.34 / Chapter 3. --- Material and Methods --- p.36 / Chapter 3.1 --- Chemicals --- p.36 / Chapter 3.2 --- Screening of freshwater and marine bacterial culture --- p.36 / Chapter 3.3 --- Photocatalytic reaction --- p.39 / Chapter 3.3.1 --- Preparation of reaction mixture --- p.39 / Chapter 3.3.2 --- Preparation of bacterial culture --- p.39 / Chapter 3.3.3 --- Photocatalytic reactor --- p.41 / Chapter 3.3.4 --- PCO disinfection reaction --- p.42 / Chapter 3.3.4.1 --- Effect of initial pH --- p.44 / Chapter 3.3.4.2 --- Effect of reaction temperature --- p.45 / Chapter 3.3.4.3 --- Effect of growth phases --- p.45 / Chapter 3.4 --- Measurement of superoxide dismutase (SOD) activity --- p.47 / Chapter 3.5 --- Measurement of catalase (CAT) activity --- p.49 / Chapter 3.6 --- Fatty acid (FA) profile --- p.50 / Chapter 3.7 --- Bacterial regrowth test --- p.51 / Chapter 3.8 --- Atomic absorption spectrophotometry (AAS) --- p.52 / Chapter 3.9 --- Total organic carbon (TOC) analysis --- p.53 / Chapter 3.10 --- Chlorination --- p.55 / Chapter 3.11 --- UV-C irradiation --- p.56 / Chapter 3.12 --- Transmission electron microscopy (TEM) --- p.56 / Chapter 4. --- Results --- p.60 / Chapter 4.1 --- Screening of UV-A resistant freshwater and marine bacteria --- p.60 / Chapter 4.2 --- Control experiments --- p.62 / Chapter 4.3 --- Treatment experiments --- p.65 / Chapter 4.3.1 --- UV-A irradiation from lamps --- p.65 / Chapter 4.3.2 --- Fluorescent light from fluorescent lamps --- p.65 / Chapter 4.3.3 --- Effect of initial pH --- p.67 / Chapter 4.3.4 --- Effect of reaction temperature --- p.70 / Chapter 4.3.5 --- Effect of growth phases --- p.70 / Chapter 4.4 --- Factors affecting bacterial sensitivity towards PCO --- p.73 / Chapter 4.4.1 --- Superoxide dismutase (SOD) and catalase (CAT) activities --- p.73 / Chapter 4.4.2 --- Superoxide dismutase (SOD) and catalase (CAT) induction --- p.74 / Chapter 4.4.3 --- Fatty acid (FA) profile --- p.75 / Chapter 4.5 --- Bacterial regrowth test --- p.78 / Chapter 4.6 --- Disinfection mechanisms of fluorescent light-driven photocatalysis --- p.79 / Chapter 4.6.1 --- Atomic absorption spectrophotometry (AAS) --- p.79 / Chapter 4.6.2 --- Total organic carbon (TOC) analysis --- p.81 / Chapter 4.6.3 --- Transmission electron microscopy (TEM) --- p.83 / Chapter 4.7 --- Chlorination --- p.89 / Chapter 4.7.1 --- Disinfection efficiency --- p.89 / Chapter 4.7.2 --- Transmission electron microscopy (TEM) --- p.92 / Chapter 4.8 --- UV-C irradiation --- p.96 / Chapter 4.8.1 --- Disinfection efficiency --- p.96 / Chapter 4.8.2 --- Transmission electron microscopy (TEM) --- p.96 / Chapter 5. --- Discussions --- p.103 / Chapter 5.1 --- Screening of UV-A resistant freshwater and marine bacteria --- p.103 / Chapter 5.2 --- Comparison of PCO coupled with UV-A lamps and fluorescent lamps --- p.103 / Chapter 5.3 --- Effect of initial pH --- p.105 / Chapter 5.4 --- Effect of reaction temperature --- p.106 / Chapter 5.5 --- Effect of growth phases --- p.107 / Chapter 5.6 --- Factors affecting bacterial sensitivity towards PCO --- p.108 / Chapter 5.6.1 --- Superoxide dismutase (SOD) and catalase (CAT) activities --- p.108 / Chapter 5.6.2 --- Superoxide dismutase (SOD) and catalase (CAT) induction --- p.110 / Chapter 5.6.3 --- Fatty acid (FA) profile --- p.110 / Chapter 5.6.4 --- Cell wall structure --- p.112 / Chapter 5.6.5 --- Bacterial size --- p.114 / Chapter 5.6.6 --- Other possible factors --- p.114 / Chapter 5.7 --- Bacterial regrowth test --- p.115 / Chapter 5.8 --- Disinfection mechanisms of fluorescent light-driven photocatalysis --- p.116 / Chapter 5.8.1 --- Atomic absorption spectrophotometry (AAS) --- p.116 / Chapter 5.8.2 --- Total organic carbon (TOC) analysis --- p.117 / Chapter 5.8.3 --- Transmission electron microscopy (TEM) --- p.118 / Chapter 5.9 --- Chlorination --- p.122 / Chapter 5.9.1 --- Disinfection efficiency --- p.122 / Chapter 5.9.2 --- Transmission electron microscopy (TEM) --- p.122 / Chapter 5.10 --- UV-C irradiation --- p.123 / Chapter 5.10.1 --- Disinfection efficiency --- p.123 / Chapter 5.10.2 --- Transmission electron microscopy (TEM) --- p.124 / Chapter 5.11 --- Comparisons of three disinfection methods --- p.124 / Chapter 6. --- Conclusions --- p.126 / Chapter 7. --- References --- p.132

The design, processing, and sequential testing of a novel cylindrical diffusing optical fiber tip for ultraviolet light delivery is described. This device has been shown to uniformly(+/- 15%) illuminate angioplasty balloons, 20 mm in length, that are used in an experimental photochemotherapeutic treatment of swine intimal hyperplasia. Our experiments show that uniform diffusing tips of < 400 micron diameter can be reliably constructed for this and other interstitial applications. Modeling results indicate that this design is scalable to smaller diameters. The diffusing tips are made by stripping the protective buffer and etching away the cladding over a length of 20 mm from the fiber tip and replacing it with a thin layer of optical epoxy mixed with A/203 powder. To improve the uniformity and ease of fabrication, we have evaluated a new device configuration where the tip is etched into a modified conical shape, and the distal end face is polished and then coated with an optically opaque epoxy. This is shown to uniformly scatter - 70% of the light launched into the fiber without forward transmission. To our knowledge, we are the first to use this device configuration, and we have achieved a uniform cylindrical pattern of laser energy with uniformity < ± 15% of the average value. A simple computational model suitable for the interpretation of laser energy irradiance along the bare core surface of multimode optical fiber tips is proposed and experimentally verified. The model used is based on geometrical optics and Gaussian approximation. Good agreement is obtained between the calculation and experiment. We have measured the optical properties of the tips through all the sequences of the fabrication. The performances of the diffusing tips for illuminating angioplasty balloons are then evaluated by Ultraviolet Light at 365 nm. A Ti:Sapphire Ring Laser System with a doubling crystal pumped by an argon ion laser is used to generate the wavelength in this study.

Phosphorus (P) is a limiting nutrient regulating productivity in both freshwater and marine ecosystems. A full knowledge of the sources and pathways of the P cycle is essential for understanding aquatic ecosystem function and for managing eutrophication. However, two significant pathways are poorly understood or remain uncharacterized. First, aquatic metazoans represent a significant internal regenerative pathway of P through the mineralization, translocation (i.e., benthic pelagic coupling) and excretion of nutrients. Rates of P excreted are expected to vary across taxa (i.e., zooplankton vs. mussels vs. benthic macroinvertebrates vs. fish), yet the significance of any one group of taxa in supplying P to bacteria and algae is unknown. Therefore, I developed the first comprehensive set of empirical models of nutrient release for aquatic metazoans (zooplankton, mussels, other benthic macroinvertebrates, and detritivorous and non-detritivorous fish) and compared inter-taxonomic differences in P excretion. I demonstrated that detritivorous fish excrete P at rates greater than all other taxa (as a function of individual organism mass); whereas, mussels generally excreted P at rates less than other taxa. Significant differences in the rate of P excretion between zooplankton and non-detritivorous fish were not observed [i.e., the allometry of P excretion was similar between zooplankton and non-detritivorous fish (as a function of individual body mass)]. I subsequently applied the models to assemblage biomass and abundance data to examine and compare the relative contribution of each taxa to the internal supply of P, and to examine the turnover time of P bound in metazoan biomass. I clearly demonstrated a hierarchy in the contribution by different metazoan assemblages to P cycling (zooplankton > benthic macroinvertebrates > mussels > fish) and clarified the significance of different metazoan taxa in P cycling. Moreover, I demonstrated that the slow turnover time of P bound in fish biomass (relative to other metazoans) indicates that fish are important as sinks rather than sources of P. A second potentially significant P pathway is through the influence of ultraviolet radiation (UVR) on P cycling. UVR may alter P cycling abiotically through changes in P availability and biotically through changes in the acquisition and regeneration of dissolved P by plankton. However, the significance of P released from the photodecomposition of dissolved organic P compounds (DOP), and the effect of UVR on the uptake and regeneration of dissolved P, the turnover of particulate P, and on ambient phosphate (PO43-) concentration has not been investigated and remains unknown. Therefore, my initial experiments applied the novel use of radiophosphate uptake assays to quantify the significance of the photodecomposition of DOP to PO43-. I concluded that the liberation of PO43- through the photodecomposition of DOP is not a significant pathway. However, the photochemical liberation of PO43- from suspended sediments was evident and should be an important pathway supplying PO43- to plankton in shallow polymictic lakes. This represents the first study to identify this P pathway in lakes. The turnover time of the PO43- pool increased under UVR irradiance (i.e., uptake of P by plankton decreased), while the regeneration rate of dissolved P and turnover rate of planktonic P were generally not affected. The net effect of UVR was an increase in steady state PO43- concentration (ssPO43-). Alkaline phosphatase activity (APA) in the dissolved and particulate fractions was significantly reduced in UVR treatments, but unrelated to changes in P uptake as proposed in the literature. This is the first study to comprehensively investigate the biotic effects of UVR on P cycling and represents a major advancement in the field of photobiology. In summary, I have characterized several poorly understood pathways in the P cycle of lakes. With the models I have developed, aquatic metazoans can now be integrated into the P cycle of lakes, for example, with other internal and external sources of P (e.g., from inlets, lake sediments and the atmosphere). This will advance our knowledge of P cycling, and will provide researchers with a better understanding of the nutrient pathways supporting primary production.

The purpose of this study was to evaluate the applied use of a commercial UV unit for air sanitation in the cold storage rooms of a local supermarket chain. On-site testing was performed in four supermarkets (two control stores without UV units and two experimental stores) and one warehouse employing UV units. Meat processing, meat storage, and produce storage rooms were randomly sampled by the open plate and swab methods. Commonly occurring "representative microorganisms" were then selected and identified as Pseudomonas sp., Flavobacterium sp., Bacillus sp., Rhodotorula sp., and Penicillium sp. which were taken into the laboratory for UV testing. Representative microorganisms were effectively killed by UV when tested in the laboratory. Exposure to UV was conducted on agar streaked plates and aerosol suspensions of the microorganisms. The effectiveness of the commercial UV unit in the applied setting was less easily determined due to a complexity of changing variables between rooms and between stores. In general, the UV unit appeared to be of noticeable benefit where airborne yeasts and molds were predominant. This occurred in produce rooms. Regular maintenance of the UV unit was necessary for maximum efficiency. The meat processing room presented unique problems relating to procedural habits of the personnel. In all supermarket cold rooms, good "housecleaning" remained the key to controlling microorganisms.Ball State UniversityMuncie, IN 47306

Phosphorus (P) is a limiting nutrient regulating productivity in both freshwater and marine ecosystems. A full knowledge of the sources and pathways of the P cycle is essential for understanding aquatic ecosystem function and for managing eutrophication. However, two significant pathways are poorly understood or remain uncharacterized. First, aquatic metazoans represent a significant internal regenerative pathway of P through the mineralization, translocation (i.e., benthic pelagic coupling) and excretion of nutrients. Rates of P excreted are expected to vary across taxa (i.e., zooplankton vs. mussels vs. benthic macroinvertebrates vs. fish), yet the significance of any one group of taxa in supplying P to bacteria and algae is unknown. Therefore, I developed the first comprehensive set of empirical models of nutrient release for aquatic metazoans (zooplankton, mussels, other benthic macroinvertebrates, and detritivorous and non-detritivorous fish) and compared inter-taxonomic differences in P excretion. I demonstrated that detritivorous fish excrete P at rates greater than all other taxa (as a function of individual organism mass); whereas, mussels generally excreted P at rates less than other taxa. Significant differences in the rate of P excretion between zooplankton and non-detritivorous fish were not observed [i.e., the allometry of P excretion was similar between zooplankton and non-detritivorous fish (as a function of individual body mass)]. I subsequently applied the models to assemblage biomass and abundance data to examine and compare the relative contribution of each taxa to the internal supply of P, and to examine the turnover time of P bound in metazoan biomass. I clearly demonstrated a hierarchy in the contribution by different metazoan assemblages to P cycling (zooplankton > benthic macroinvertebrates > mussels > fish) and clarified the significance of different metazoan taxa in P cycling. Moreover, I demonstrated that the slow turnover time of P bound in fish biomass (relative to other metazoans) indicates that fish are important as sinks rather than sources of P. A second potentially significant P pathway is through the influence of ultraviolet radiation (UVR) on P cycling. UVR may alter P cycling abiotically through changes in P availability and biotically through changes in the acquisition and regeneration of dissolved P by plankton. However, the significance of P released from the photodecomposition of dissolved organic P compounds (DOP), and the effect of UVR on the uptake and regeneration of dissolved P, the turnover of particulate P, and on ambient phosphate (PO43-) concentration has not been investigated and remains unknown. Therefore, my initial experiments applied the novel use of radiophosphate uptake assays to quantify the significance of the photodecomposition of DOP to PO43-. I concluded that the liberation of PO43- through the photodecomposition of DOP is not a significant pathway. However, the photochemical liberation of PO43- from suspended sediments was evident and should be an important pathway supplying PO43- to plankton in shallow polymictic lakes. This represents the first study to identify this P pathway in lakes. The turnover time of the PO43- pool increased under UVR irradiance (i.e., uptake of P by plankton decreased), while the regeneration rate of dissolved P and turnover rate of planktonic P were generally not affected. The net effect of UVR was an increase in steady state PO43- concentration (ssPO43-). Alkaline phosphatase activity (APA) in the dissolved and particulate fractions was significantly reduced in UVR treatments, but unrelated to changes in P uptake as proposed in the literature. This is the first study to comprehensively investigate the biotic effects of UVR on P cycling and represents a major advancement in the field of photobiology. In summary, I have characterized several poorly understood pathways in the P cycle of lakes. With the models I have developed, aquatic metazoans can now be integrated into the P cycle of lakes, for example, with other internal and external sources of P (e.g., from inlets, lake sediments and the atmosphere). This will advance our knowledge of P cycling, and will provide researchers with a better understanding of the nutrient pathways supporting primary production.

The photoprotect compound mycosporine-like amino acids ( MAAs ) are a family of secondary metabolites can protect organisms exposed to solar ultraviolet radiation ( UVR ), only produced in the algae. Analyzed by HPLC, only Alexandrium minutum Halim ( Dinophyceae ) produces MAAs among seven marine microalgae species. The strains named AM-2¡BAM-3¡BAM-4 and AM-6 showed the positive results for producing the MAAs, but not AM-5. Researches on the stability the MAAs extracts from algal powder ( AM-3 ) hold at 4¢J, 25¢J and 50¢J for 35 days and light expose. The results showed the MAAs gradually decayed after 35 days at 50¢J, after exposed to UVR but decreased 48 % in one day and disappeared in two days. The growth and the MAAs produced in A. minutum ( AM-4, AM-6 ) under different salinity, nitrate concentration and UVR were analyzed to find their relationships. When the salinity increased ( 15 psu¡B25 psu¡B35 psu¡B45 psu ), the cell densities of both strain decreased significantly, but with similar MAAs composition and contents. In higher nitrate nutrient ( 2 N ), the cells produced more MAAs than those cultivated in lower nitrate ( N / 10¡BN / 2 ). Under the UV treatment with the deficient nitrate nutrient, the concentration of MAAs in A. minutum decreased after exposed to UVR for 14 hours. However, provided enough nitrate nutrient ( 2 N ), UVR can induced A. minutum to produce higher concentration of MAAs. These results showed MAAs may serve as a nitrogenous compound for intracellular storage, and not as a substance for osmotic adjustment. UVR is an important factor which induce MAAs produced in A. minutum.

Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Laurie Grubbs, Florida State University, School of Nursing. Title and description from dissertation home page (viewed 6/16/04). Includes bibliographical references.

Thesis--Utrecht. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1942. / Includes bibliographical references (p. 68).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1941. / Bibliography: leaves 91-93.