Search

Systemic lupus erythematosus (SLE) is a heterogenous autoimmune disease characterized by dysfunction within the innate and adaptive immune systems. The breakdown in immune tolerance that accompanies this promotes aberrant B cell activation, production of autoantibodies targeting self-nucleic acids, overproduction of pro-inflammatory cytokines, and widespread tissue damage. While some patients experience persistently active disease, most SLE patients follow a relapsing-remitting course with periods of clinical quiescence interspersed with unpredictable disease flares. Delineating the underlying mechanisms that contribute to pathogenesis of SLE as well as those that trigger flares will aid in development of novel therapeutics to improve patient outcomes. Several cytokines have been implicated in SLE including type I interferons (IFNs) and the IL (interleukin)-1 superfamily. Type I IFNs are overexpressed in both the circulation and non-lesional skin of SLE patients compared to controls. Levels of type I IFNs correlate with disease activity and severity and promote increased death of SLE keratinocytes after exposure to ultraviolet (UV) light. This likely contributes to photosensitivity, or enhanced sensitivity to UV light, which is experienced by up to 90% of patients. The IL-1 family of cytokines includes IL-1beta (IL-1β) which is activated by the inflammasome, a component of the innate immune system that detects infectious or endogenous danger signals. Inflammasome inhibition in lupus-prone mice improves several disease manifestations including nephritis. The specific mechanisms by which cutaneous type I IFNs contribute to photosensitivity and IL-1β influences lupus pathogenesis are currently unknown. The primary focus of this dissertation is to examine the role of type I IFNs in the skin and IL-1β in the kidney. The first objective of this study was to explore the activation and regulation of cell death pathways in keratinocytes exposed to type I IFNs and UV irradiation. Immortalized human keratinocytes were treated with IFN-α and UVB light in combination with apoptosis, necroptosis, and pyroptosis inhibitors or neutralizing antibodies. Cell death was measured by Annexin V and propidium iodide or cleaved caspase-3 staining. We identified enhanced activation of caspase-8-dependent apoptosis in IFN-primed keratinocytes after UVB exposure. This apoptosis occurred independently of known caspase-8-activating death ligands but was dependent on interferon regulatory factor 1 (IRF1). Lastly, we observed increased UVB-induced keratinocyte apoptosis in mice that overexpressed epidermal IFN-к compared to wild-type mice. Together, these data suggest that photosensitivity exhibited by SLE patients may result from IFN priming of keratinocytes that drives IRF1 expression and sensitizes cells to undergo increased apoptosis after minimal exposures to UVB. Continued investigation into mechanisms by which this occurs will provide prophylactic options to prevent SLE flares. The second part of our study involved investigating how loss of IL-1β affects disease severity in the lupus-prone NZM2328 mouse model. We generated a knockout strain (NZM-Il1b-/-) and examined common manifestations of disease. Surprisingly, loss of IL-1β did not affect overall survival, autoantibody generation, or renal immune cell infiltration; however, it did worsen renal immune complex deposition and proteinuria, specifically in female mice. IL-17 and TNF signaling pathways were enriched in the kidneys of female NZM-Il1b-/- mice, suggesting a potential mechanism by which nephritis is aggravated. Female patients with lupus nephritis also demonstrate upregulation of these signaling pathways, suggesting they may be of clinical relevance. Together, these data suggest that blocking IL-1β may need to be approached with caution in SLE patients, especially those with nephritis, to prevent potential exacerbation of disease.

The egg production industry contributes significantly to the US economy. However, the egg industry is facing animal welfare, bird health, biosecurity, food safety, air emissions, manure management and environmental challenges. The incidence of emerging infectious diseases relating to livestock production has been increasing over the last century. Disease outbreaks such as colibacillosis and High Pathogenicity Avian Influenza (HPAI) have resulted in losses of millions of birds and dollars in the last few decades. However, the biosecurity control methods currently used for pathogen control have not curbed this rise in infectious diseases. Additionally, air pollutant emissions in the environment, such as particulate matter (PM), from poultry facilities have been associated with increased rate of respiratory diseases and bird mortality, decreased bird performance, and the transmission of pathogens. It is critical to focus on the development of practical and economically viable technologies to control both pathogens and PM emissions is urgently needed to improve air quality both indoors and in nearby environments, and protect the health of the poultry, workers, and the environment around these facilities.The objective of this project was to identify viable pathogen control technologies for poultry facilities. From the literature review of economic feasibility, practicality, and PM removal potential, it was found that an electrostatic precipitator (ESP), an ESP used in conjunction with an ultraviolet (UV) light (ESP+UV), and an electrostatic spray scrubber (ESS) were promising technologies for pathogen control. Their pathogen removal capabilities needed to be evaluated for potential use in a poultry production facility. Thus, field tests of the pathogen removal efficiency of a full-scale ESP optimized for PM control were conducted at a commercial egg production facility in summer conditions. Three types of airborne bacteria emitted from the facility were sampled including total bacteria, Campylobacter spp., and E. coli along with PM concentrations. Parameters determining the inactivation efficiency of the ESP for each of the three bacteria samples were determined as well. These same tests were performed for the ESP+UV and ESS systems. The ESP and ESP +UV demonstrated mean total bacteria and Campylobacter spp. removal efficiencies of 59.7% and 78.9% respectively. The ESP+UV showed total bacteria, Campylobacter spp., and E. coli removal efficiencies of 62.6%. 87.7%, and 100% respectively, although very few colonies were observed for E. coli. The airborne pathogen removal efficiencies for the ESP and ESP+UV were generally higher compared to previously tested technologies. The ESS demonstrated mean total bacteria, Campylobacter spp., and E. coli removal efficiencies of 38.8%, 39.7%, and 63.2%. The removal efficiency of the ESS was lower than what was observed for the ESP and ESP+UV. Economic analysis of the ESP, ESP+UV, and ESS modular systems at a poultry facility suggest that these systems are both efficient and potentially economically feasible, although the ESS seems the most viable of the three. Overall, the outcome of this study provides knowledge, methods, and recommendations that can be used to guide implementation of ESP, ESS, and UV systems for PM and pathogen mitigation at a commercial poultry facility to protect human, animal, and environmental health. Future studies should be performed to optimize and further evaluate the effects of these pathogen control technologies on endotoxins, fungi, and viruses, as well as other potentially pathogenic bacteria such as Salmonella and Mycoplasma.

The "ophthalmohelioses" represent a conglomeration of ocular surface and adnexa disease strongly influenced by increased ultraviolet light B exposure. Despite overlapping pathogenesis pathways, the severity of these differs across the different spectrums. Ocular surface squamous neoplasia (OSSN), pterygium and conjunctival melanocytic lesions represent the three most impacting subtypes of such "ophthalmohelioses" affecting the ocular surface. OSSN represents a broad class of squamous dysplastic lesions ranging from benign papillomas till invasive squamous cell carcinomas. Melanocytic tumours such as primary acquired melanosis have a great propensity to become malignant, especially if cells are atypical. Finally, pterygium is a benign growth commonly treated with surgical excision, but patients often face an endless remitting-relapsing cycle of pterygium recurrence and repeat surgery. If untreated, patients sight limitation secondary to visual axis invasion. The early detection of OSSN, pterygium and melanocytic lesions is non-existent and often disease requires to be excised and subsequently microscopically analysed before a formal conclusion is made. For pterygium, the identification of Fuchs' Flecks at the head of pterygium may serve as satellite cells ahead of the main pterygium body. Handedness may serve a role in the eye in which pterygium is worse or develops. From a therapeutic point of view, these three "ophthalmohelioses" tend to recur consistently despite optimized treatments. This therapeutic dilemma presents themes of concern, including vision disruption, secondary to repeat surgeries given the relapsing-remitting characteristic of all three disease entities. Topical eye drops such as interferon alfa-2b combined with retinoic acid serve as a potential solution which offer superior tumour-free follow-up and rapid tumour resolution of OSSN or primary acquired melanosis lesions. The viral influence of human papilloma virus upon OSSN may be mitigated with the application of topical cidofovir. Additionally, specialized pterygium surgery may be an effective alternative to otherwise other subtypes of pterygium excision, others often being anatomically more destructive. At essence, a focus of novel therapeutic options that target pathways within "ophthalmoheliosis" pathogenesis is being presented within this thesis which may hopefully improve and expand ophthalmologist's arsenal against disease spectrums very relevant to the Australian populace.

Nonthermal treatments are increasingly used in food processing due to their potential of microbial inactivation with minimal physicochemical and sensorial quality damage to the food products. Recent advances in Light Emitting Diodes (LED) technology have shown great potential in food preservation, due the lower energy consumption and higher flexibility in design than traditional mercury or gas discharge lamps. This study investigates the use of LED technology in both Ultraviolet (UV) and visible range for inactivation of foodborne bacteria, under lower temperature conditions. One strategy of inactivating bacteria in foods and food processing environment is by using germicidal short- wave UV-C light (200 to 280 nm), which is typically emitted by mercury or amalgam lamps. UV-C LEDs were recently developed as a chemical-free, energy-efficient alternative to deliver germicidal UV and mitigate microbial contamination on material surfaces, but their effectiveness has not been fully explored. One of the objectives of this work was to gain a better understanding of the antimicrobial effectiveness of UV-C LEDs. Specifically, the inactivation kinetics of Escherichia coli ATCC 25922 and Listeria innocua FSL C2-0008 was studied by exposing them to a custom-made UV-C LED array (λ max =280 nm) under a variety of substrate conditions commonly encountered in food processing and handling environment. UV- C resulted in over 5-log reduction of both bacterial strains after 600 s in thin liquid films (thickness ≤ 0.6mm), and on all stainless steel (SS) surfaces. The fastest initial inactivation was achieved on dry SS i surfaces for both bacteria, but maximum inactivation was similar for the dry and wet conditions. The results of this work can help end users design effective and efficient UV-C LED disinfection strategies for various surface conditions. Another approach for eliminating undesirable bacteria in food processing environments is by using antimicrobial blue light in the wavelength spectrum of 400-470 nm. Previous work suggested that 405 nm light has maximum antimicrobial effects in this range, but the effectiveness of the treatment has not been fully explored. In this work, the efficacy of 405 nm LED against Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Typhimurium, and Staphylococcus aureus, and the effect of substrate on inactivation kinetics were investigated. Additionally, the influence of nanoscale surface topography on the inactivation behavior of pathogenic E. coli, L. monocytogenes, and S. aureus was evaluated. Exposure to 405nm LED resulted in over 5-log reduction for P. aeruginosa and S. aureus in liquid films after 48 h. Maximum inactivation was observed for E. coli on stainless steel (SS) surfaces; the highest rate of inactivation was observed on small nanopore anodic aluminum oxide (AAO) for L. monocytogenes and S. aureus, with over 5-log reduction achieved after 12 h, suggesting potential inactivation enhancing properties of nanoscale topography. The results suggest that 405 nm LEDs have great potential for antimicrobial treatments in the food industry, but disinfection success depends on bacterial species, substrate, and environmental conditions. Additionally, surfaces with nanoscale topography may offer additional inactivation enhancing properties. Overall, these approaches can have positive impacts on food safety and quality. This study demonstrates that LED technology can play an important role in combating foodborne bacteria in food processing and handling environments, clinical environments, as well as other areas relevant to human health.

While many mutation assays already exist, they are often either extremely costly or ineffective at providing molecular and mechanistic information about a mutagen. These assays are often assembled into a workflow from inexpensive less informative assays to expensive informative assays. This study sought to develop an assay to allow for more detailed information to be generated inexpensively in the early stages of a mutagen assessment workflow.A plasmid designed and constructed for mutation measurement using Ion Torrent Next Generation Sequencing was stably transfected into HeLa cells. To elucidate this assay’s ability to measure mutation, transfected cells were then exposed to three doses of the LD50 for ultraviolet light for a total exposure of 6 mJ/cm2. Finally, genomic DNA from mutated and non-mutated cells was isolated and sequenced to measure induced mutation. Genomic DNA was successfully sequenced from transfected cells, and an increase in percent mutation was seen between mutated and non-mutated cells. No statistically significant sequence specific mutation rate could be determined and this study was unable to show that this induced mutation was consistent with the known mutation signature of ultraviolet light. Nonetheless, these results represent a proof of concept and demonstrate that this assay can be used to measure mutation.

This master’s thesis is comprised of one technical paper and two public archaeology initiatives that support the creation of a significant digital heritage product that utilizes citizen science to further the stewardship of archaeological and historical resources. The first chapter is comprised of a methodological use of the Video Spectral Comparator 6000 and ImageJ software. The methodology explores quantitative and qualitative aspects of lithic sourcing utilizing ultraviolet light treatments on two macroscopically similar lithic material sources, Knife River Flint and White River Group Silicates. The development of a non-destructive, non-invasive method to source lithic raw materials provides a tool for researchers to simplify and standardize the process of qualitative lithic sourcing using ultraviolet fluorescence. The second chapter examines the role that professional archaeologists and private landowners can play in the realm of public outreach in the High Plains. Utilizing the case studies from United States Forest Service sponsored ‘Artifact Roadshows’, this chapter provides methodological guidelines aimed toward professional archaeologists utilizing interpretation as a way to create collaborative relationships with private landowners. Finally, the third chapter contains the implementation of a digital archive which utilizes citizen science efforts and data derived from the ‘Artifact Roadshows’. This digital archive provides sound, analytical data for professional archaeologists and educational materials derived from analytical data for the consumption of the general public. Advisor: LuAnn Wandsnider & Matthew Douglass

The internal structure of casein micelles is not fully understood. In the present work, we explore some of the basic questions about casein micelles in bovine milk including its size distribution, native binding properties and effect of ultra-high pressure homogenization (ultra-HPH) on technological properties of casein micelles. The size distribution of casein micelles was studied by cryo-TEM using skim milk from four cows. The degree of variation in casein micelle sizes (polydispersity) ranged between 0.39 and 0.47 for a size distribution ranging from 10 to 693 nm. These results indicated high polydispersity of casein micelles in milk from single cows. Casein micelles associated with vitamin A in four pasteurized skim milks (1.6 - 2.5 micro gm/mL of milk; 14 - 40% of the initial quantity detected in milks), while other protein fractions contained negligible vitamin A. Thus, casein micelles can inherently associate with hydrophobic probes like vitamin A in milk. This association of vitamin A to casein micelles in milk provided protection from degradation on exposure to ultraviolet light when compared to apple juice. Further, the effect of ultra-HPH up to 500 MPa on the physicochemical (apparent casein micelle size by dynamic light scattering) and technological characteristics (rennet coagulation - firmness [ 90 min, 1Hz, 0.01% strain]; acid gelation using 3%w/v glucono delta lactone – firmness [22°C, 110 min, 1Hz, 0.01% strain], SDS-PAGE) of casein micelles were studied. Casein micelle size increased from ca. 180 nm at 100 MPa to ca. 280 nm at 500 MPa HPH pressure. With increase in HPH pressure, renneting ability decreased until no coagulation was obtained for 500 MPa HPH milk. The firmness of HPH milk acid gels increased from about 76 Pa to 108 Pa when pressure was increased above 100 MPa (up to 400 MPa) HPH as compared to acid gels made from non-homogenized milk. Overall we elucidated the size distribution, binding ability to vitamin A and changes occurring on ultra-HPH in casein micelles. This information can be utilized by the industry to modify and utilize casein micelles as an ingredient for different end uses.

Abstract: Absorption of UV light by nucleic acids can result in the formation of molecular lesions leading to mutagenesis, carcinogenesis, and cell death. Thus, understanding DNA damage is important for elucidating the molecular mechanisms of disease. Much effort has been focused on developing methods for detecting DNA damage. However, almost all of the proposed methods consist of multi-step procedures, are limited to a specific type of damage, require expensive instruments, and/or suffer from a high level of interference. In this thesis, I present some novel simple, mix-and-read fluorescent assays for the detection of DNA damage. The goal is to design probes that are superior to conventional fluorescent molecular beacons (MBs) in detecting DNA damage. The first approach was to design MBs with modified DNA backbones. For this purpose, locked nucleic acid (LNA) and chimeric RNA-DNA (chMB) MBs were designed. The results show that chMBs are more sensitive and selective for DNA damage than LNA MBs that have comparable selectivity to conventional MBs. However, these probes show a signal that is inversely proportional to the amount of damage. Therefore, the second approach was to design probes that give signals directly proportional to the amount of damage. For this purpose, probes with 2-aminopurine (2AP) were designed. Such probes show no fluorescence for undamaged DNA and fluorescence for damaged DNA. 2AP probes offer high sensitivity and selectivity comparable to MBs, but are expensive, especially with an increasing number of 2APs in the probe to increase sensitivity. Thus, the hypochromism probe was designed. For this probe, the absorbance signal increases with increasing amount of damage. Results show that the hypochromism probe is more selective and more than ten times cheaper than conventional MBs, but less sensitive. The need for a sensitive, selective and inexpensive probe was the motivation to design the Tb3+/hairpin probe. Single-stranded DNA greatly enhances the Tb3+ emission, but duplex DNA does not. Undamaged DNA targets will hybridize with the hairpin with no emission. The Tb3+/DNA hairpin probe proves to be the cheapest, most sensitive and selective probe for the quantification of DNA damage of all the probes presented here.

NF-κB is a transcription factor that controls expression of genes involved in the immune and inflammatory responses as well a being a key component in the onset of cancers. In this study we provided evidence that MSK1 is responsible for a non-canonical late-phase activation of NF-κB upon UVB irradiation. Our data demonstrated that following UV irradiation, MSK1 is activated via phosphorylation at the 24 h time point coinciding with translocation of NF-κB into the nucleus. Investigations into the signaling pathways upstream of MSK1 through the use of specific inhibitors for mitogen-activated protein kinase and p38 revealed that both kinases are required for full phosphorylation during the late-phase (24 h), while p38 is paramount for phosphorylation during the early-phase (6 h). Electromobilty shift assays (EMSA) showed that inhibition of MSK1 resulted in a marked reduction in NF-κB binding affinity without altering the nuclear translocation of NF-κB. Supershift EMSA implicate that the p65, but not p50, isoform of NF-κB is involved in late-phase activation in response to UVB irradiation. Together, the results of these studies shed light onto a novel pathway of MSK1 mediated late-phase activation of NF-κB in response to UV irradiation.Exposure to UV induces a prolonged expression of COX-2 via transcriptional activation that is due in part to an increase in NF-κB activity. While transcriptional regulation of COX-2 expression has been well studied, the role of translational regulation of COX-2 synthesis upon UV-irradiation is not yet clear. In this study, we show that the phosphorylation of the alpha subunit of eIF2α plays an important role in the regulation of COX-2 expression after UV-irradiation. Our data demonstrates that UV light induces COX-2 expression in wild-type mouse embryo fibroblasts (MEFS/S) and that the inducibility is reduced in MEFA/A cells in which the phosphorylation site, Ser-51 in eIF2α, is replaced with a nonphosphorylatable Ala (S51A). UV light-induced transcription of COX-2 is delayed in MEFA/A cells, which correlates with NF-κB activation as we previously reported (Wu et. Al, J. Bio. Chem, 2004). Additionally, the translational regulation of COX-2 binding protein TIAR expression is reduced in MEFS/S cells but not in MEFA/A cells at 24 hours post-UV. These results suggest that translation initiation plays a role in a complex and dynamic regulation of COX-2 expression. Based on our results we proposed a novel eIF2α phosphorylation-centered network for the regulation of COX-2 expression after UV irradiation.

Non-melanoma skin cancer (NMSC), consisting of cutaneous basal cell carcinoma and squamous cell carcinoma (cSCC), is the most common form of cancer in the world. In 2006, the estimated number of new NMSC cases in the United States rose to 3.5 million; of those, 700,000 were cSCCs. The most important factor for the development of primary cSCCs is cumulative exposure to ultraviolet radiation. Other environmental risk factors include viral infection, immunosuppression, chronic inflammation, and exposure to industrial carcinogens. Cancer development is not solely dependent on environmental factors as a genetic contribution for several cancers is well described. Population and family-based studies suggest that there is a genetic component to the development of cSCC. These studies suggest heritability for cSCC risk; however, the specific genetic factors remain elusive. This dissertation is comprised of three related projects that explore the genetic contribution to cSCC. These studies utilize both skin cancer susceptible and resistant mice and human samples. Because human populations are heterogeneous, the use of mouse models to map genetic risk factors is ideal. Cancer susceptibility genes identified in the mouse have been confirmed in human studies suggesting this is an effective approach to identify true genetic risk factors. Previous studies using these mice identified skin tumor susceptibility loci, including the one of focus for this study, Skts5, as well as a small number of microRNAs (miRNAs) showing differential expression. The goal of the first project was to identify and characterize novel skin cancer susceptibility genes in the mouse. We hypothesized that genes mapping to Skts5 which showed expression differences and/or sequence variations between cancer susceptible and resistant mice may be playing a role in tumorigenesis. We identified aryl hydrocarbon receptor (Ahr) as a potential candidate susceptibility gene. We performed in vitro functional analyses and revealed potential roles that Ahr may be playing in tumor development and progression. The focus of the second project was to identify cancer susceptibility genes at the human SKTS5 locus using allele-specific imbalance and risk association studies. We hypothesized that human cSCC tumors would show allele-specific somatic genetic changes at SKTS5 and that these alterations would contribute to cSCC risk. Candidate genes identified in the mouse were analyzed in human samples. We identified single nucleotide polymorphisms and haplotypes in HDAC9 that conferred risk, supporting my hypothesis. The goal of the third project was to identify and characterize miRNAs that are playing a role in cSCC tumorigenesis. This project utilized a miRNA microarray expression data set to compare expression in cSCC cancer susceptible and resistant mice. We hypothesized that miRNAs showing differential expression between the strains are important in the development of cSCC. This study identified six miRNAs and we performed in vitro functional characterization of miR-1.Genetic discovery is important to not only understand the biology of disease, but to also facilitate better preventative measures and treatment options. The three studies of this dissertation give insight to genes and miRNAs contributing to cSCC development.

The objectives of this study were to reduce the microbial contamination of fruit juice, different treatments were applied in order to treat microorganisms efficiently without degradation of bioactive nutrient values and to reduce unnecessary waste and time. This dissertation is divided in five chapters: Chapter one reviews numerous studies of the impacts of batch or continuous flow ohmic and microwave heat treatments as a novel technology on nutritional values, enzymatic inactivation, and microbial destruction. Profiles during processing were needed to predict the effect of using different temperatures. Additionally, UV-light is tested an alternative to traditional pasteurization for inactivation of microorganisms. Chapter two includes continuous flow ohmic heating for pasteurization of raisin juice. This study attempted to establish kinetic models of raisin juice inoculated with E. coli K-12 that was treated using a continuous flow ohmic heater (50, 60, 70, and 80˚C) with different residence times (23 to 208 s). The results showed that continuous flow ohmic heating was more efficient compared to conventional heating at the same conditions to reduce the microbial and PME activity, and it minimized the loss of total phenolic acids and antioxidant values in raisin juice. Chapter three covers simulation to validate the percentage of antioxidants levels and heat distribution of grape juice when pasteurized by ohmic heating with different residence times by comparing experimental data with numerical simulation. The result showed the outlet temperature profiles of 60, 70 and 80˚C were similar to simulation data within 2-3˚C. However, the correlation coefficient between experimental and simulation data for antioxidant levels after ohmic treatments was above of 0.92. Chapter four aimed to investigate the effect of continuous flow microwave heating on the reduction of microorganisms in kava juice to extend the shelf life. Chemical and microbial properties of treated juice were analyzed using key parameters such as microbial counts, kavalactones, and pectin methylesterase activities. The results obtained from this chapter showed that continuous flow microwave heating was confirmed to be more efficient than the conventional method for the inactivation of microorganisms and pectin methylesterase, and there was no indicator to show significant deterioration of kava juice quality. Chapter five involves apple juice inoculated with E. coli K-12 and exposed with pulsed ultraviolet (PUV) and non-pulsed ultraviolet (NPUV) modes as continuous and batch light treatments for 11 to 51 ml/min and 5 to 15 mins respectively. The highest log reductions of E. coli K-12 in apple juice after PUV and NPUV as continuous system were 3.35 and 3.99, respectively, at 11ml/min. Also, log reductions reached 0.85 and 1.35 in samples pasteurized by PUV and NPUV, respectively, as batch systems after 15 mins. In addition, there was no significant difference between PUV and NPUV as continuous and batch systems.

The increase of ultraviolet (UV) light levels in the northern hemisphere raises the spectre of possible problems for turfgrass plants due to long term exposure. Cool season turfgrasses which are susceptible to photoinhibition may suffer from a loss of productivity and growth, reducing their ability to sequester carbon. The effect on germination, plant responses in relation to UV absorbing compounds and how turfgrasses were evaluated for loss of quality with regards to linking new technology to visual ratings have had no or limited research. Enhancing the percentage of Kentucky bluegrass (Poa pratensis L.) seed germination and speed could benefit establishment of the grass in a greater range of environmental and geographical conditions. Potential for the use of ultraviolet light to enhance Kentucky bluegrass seed germination exists through exposure to UV light. The effect of ultraviolet light may be lost with seed age. In altering wavelength exposure, there may be an opportunity to enhance the effect. In measuring turf quality, traditionally human measurement has been the standard method for both color and cover. Color, in particular, is thought to be controlled by pigment changes. In evaluating a total of 51 cultivars of tall fescue (Schedenorus phoenix Scop. Holub), perennial ryegrass (Lolium perenne L.) creeping bentgrass (Agrostis stolonifera L.) cv. ‘Penncross’ and ‘L-93’ it was found that nitrogen content is most crucial in color measurements. Reflective measurements did not correlate with nitrogen or chlorophyll content. Extract measurements had stronger correlation with nitrogen content than pigmentation concentration. Current reflective measurement equipment may not be closely linked to visual rating of turfgrass color possibly due to variation in leaf surfaces.There is a difference in response to UV light among grass species. Creeping bentgrass ‘L-93’ produced increasing anthocyanin in response to UV light. The characterization of Cyanidin – 3 – O – glucoside was the first reported in the literature in creeping bentgrass. Carotenoids, zeaxanthin and β-carotene decrease in creeping bentgrass after exposure to UV-B and turfgrass quality and vegetative production in bentgrasses decreased to a greater extent than tall fescue or perennial ryegrass. All grasses have the ability to initially accumulate phenolic compounds and flavonoids in the tissue most exposed to light, although this still doesn’t mean a prevention in damage to photosynthetic machinery. Turfgrass recovery and maintenance of optimal photosynthetic rates will be crucial as breeders try to develop new cultivars that are adapted to higher levels of UV light.

Abstract: Ultraviolet (UV) light is one of the most abundant DNA damaging agents. The major DNA lesions, such as cyclobutane pyrimidine dimers (CPDs) and (6-4) pyrimidine pyrimidone (64PPs) photoproducts, are carcinogenic and mutagenic. Studies of the formation, repair and mutagenicity of these DNA lesions induced by environmentally relevant doses of UV irradiation require sensitive and specific techniques for their detection. This thesis focuses on the development and application of an immunoassay combining capillary electrophoresis (CE) separation with laser induced fluorescence (LIF) detection. Primary monoclonal antibodies binding to either CPDs or 64PPs were used as the affinity recognition probes. A fluorescently labeled secondary antibody fragment (Fab) was used to bind to the primary antibody. The immunocomplexes of the DNA lesions with the antibodies were separated from the excess amounts of antibodies by using CE. The fluorescent intensities of the immunocomplexes containing the DNA lesions were measured for quantitative determination of CPDs and 64PPs. Synthetic standard oligonucleotides (16 bases in length) containing a single CPD or 64PP were used for quantitative calibration. Successful determination of CPDs in UV-irradiated 80-nucleotide (nt) DNA library, calf thymus DNA, human placenta DNA and human fibroblast cells demonstrated the applicability of this CE-LIF immunoassay. Irradiation of the random oligonucleotide sequences, naked DNA and cells with varying doses of UVB and/or UVC provided useful information on the relative yield of the formation of the UV-induced DNA lesions. The yield of CPD formation in the cellular DNA of CRL-2522 fibroblasts (3.6 ± 0.8 lesions per 103 nt per J/cm2) following irradiation with low doses of UVB (< 0.3 J/cm2) was approximately 7 times lower than that in the naked calf thymus DNA (26.8 ± 1.4 lesions per 103 nt per J/cm2). A fluorescently labeled oligonucleotide (90nt in length) containing a single CPD was designed, synthesized and partially characterized. It could potentially be used as a probe to study interactions between CPD-containing DNA and nucleotide excision repair proteins, or as a probe to screen for binding proteins or antibodies. The CE-LIF immunoassay takes advantage of antibody affinity, CE separation and highly sensitive LIF detection. Further potential applications include studies of DNA repair, monitoring of DNA damage and environmental biomarker development.

Membrane rafts, or lipid rafts, are microdomains of the plasma membrane enriched in cholesterol and sphingolipids, and play an important role in regulation of apoptosis. The structure of membrane rafts is dynamic, resulting in an ever-changing content of both lipids and proteins. Cholesterol, a major component of membrane rafts, is critical for the formation and configuration of membrane raft microdomains, which provide signaling platforms capable of activating both pro-apoptotic and anti-apoptotic signaling pathways. A change of cholesterol level can result in membrane raft disruption and activate or deactivate raft-associated proteins, such as death receptor proteins, protein kinases, and calcium channels. This study focuses on the role of membrane rafts of HaCaT keratinocytes in ultraviolet light (UV)-induced apoptosis. HaCaT keratinocytes readily undergoes apoptosis upon exposure to UV light mediated by association of clustered membrane rafts with the activated Fas death receptor. This study demonstrates the cholesterol dependence of UV-induced Fas activation and apoptosis in HaCaT cells. At one hour following 50 mJ/cm2 ultraviolet B (UVB) irradiation, raft cholesterol levels are increased while raft ceramide levels are decreased, Fas receptor activation occurs in the membrane rafts, and apoptotic PARP cleavage is evident. Decreased amounts of the Fas-recruited apoptotic Daxx protein following UVB irradiation suggests that the apoptotic caspase cascade pathway is more important in the initiation on UV-induced apoptosis than the alternative JNK pathway in HaCaT cells. The proposed mechanism by which membrane raft clustering causes Fas activation provides clues to understanding the role of membrane raft clustering in other cellular signaling processes.

The interaction of intense laser pulses with nanometer scale atomic clusters has been an active area of study since the advent of amplified femtosecond lasers. In the case of infrared irradiation of noble gas clusters, direct field-driven ionization results in the ejection of energetic electrons, high ion charge states, and Coulomb explosion of the ion core of the clusters. These processes result from electron motion driven by the cluster potential and the large ponderomotive potential of the laser field. When extreme ultraviolet (XUV) pulses interact with clusters, the mechanisms responsible for the infrared response are 'turned off' because the ponderomotive potential is very small. We have conducted cluster experiments at 38nm using focused XUV pulses produced by high harmonic generation with a 15TW Ti:Sapphire laser. We measured the charge states and kinetic energy spectra of ions produced in the interaction, and observe substantial ion population up to Xe⁵⁺, with a small number of Xe⁶⁺-Xe⁸⁺ ions produced by collisional ionization by hot plasma electrons. The ion kinetic energy spectrum indicates a hydrodynamic expansion at an ion temperature of 8eV. This is in stark contrast to intense infrared/cluster interactions, where clusters are stripped of electrons to a large degree and expand by Coulomb forces, resulting in far higher ion kinetic energy for similar degrees of ionization.

The use of ultraviolet-initiated (UV-initiated) advanced oxidation processes (AOP) is rapidly becoming an attractive alternative for the degradation of emerging organic contaminants that are not easily removed using conventional water treatment processes. Design and optimization of UV/H2O2 systems must incorporate both reactor design (hydrodynamics, lamp orientation) and chemical kinetics (reaction mechanisms, kinetic rate constants). This research lays the groundwork for a protocol for using CFD models to simulate UV-initiated AOPs and, in doing so, provides the start for an improved design process to meet the needs of the water treatment community. In this CFD model, the combination of turbulence sub-models, fluence rate sub-models, and kinetic rate equations results in a comprehensive and flexible design tool for predicting the effluent chemical composition from a UV-initiated AOP reactor. To validate the CFD simulation, the results of the model under various operating conditions were compared to pilot reactor trials for the target contaminants of an organic dye (methylene blue) and an antibiotic (sulfamethoxazole). The CFD model tends to under-predict the percent removal of methylene blue within the reactor. In addition, the percent difference between the pilot and the CFD results increases with increasing flow rates. Similar to the methylene blue trials, the CFD simulations for sulfamethoxazole degradation under-predict the percent removals measured in the pilot reactors. The sensitivity to model parameters was evaluated. The MSSS sub-model predicted higher fluence rate values than that of the RAD-LSI sub-model. This increase in fluence rate translates to higher contaminant removal percentages predicted for both methylene blue and SMX. The turbulence sub-model selection for this reactor configuration was found to not significantly impact the predicted removal for methylene blue. As expected, the overall degradation of methylene blue was a strong function of the value of the second-order kinetic rate constant describing the reaction between methylene blue and the hydroxyl radical. Further, the overall removal of methylene blue was shown to be sensitive to the concentration of the radical scavenger dissolved organic carbon in the water matrix.

Non-melanoma skin cancer is an extensive and growing problem in the United States and around the world. Of particular concern is the dramatically increased prevalence of non-melanoma skin cancer in therapeutically immunosuppressed patients. The most studied population concerning this problem is solid organ transplant recipients. The immunosuppressive therapy they receive to prevent organ rejection has been implicated in this problem of increased skin cancer. However, the specific mechanisms by which these agents cause increases in skin cancer are not well understood. We used the Skh-1 hairless mouse model of UVB induced skin carcinogenesis to examine the effects of two immunosuppressive agents, cyclosporine A (CsA) and sirolimus (SRL). These two agents have very different mechanisms of action and as it turns out very different effects on UVB induced inflammation and carcinogenesis. We also tested the hypothesis that using both drugs in combination would result in further reduced inflammation and therefore reduced tumor development and progression. By examining key stages of the carcinogenesis process we have found important differences in the effects of each of these agents alone and in combination on UVB induced inflammation and skin carcinogenesis. The first step was to determine if these agents caused differences in the acute UVB response. We examined markers of post-UVB inflammation such as edema, myeloperoxidase (MPO), and dermal neutrophil infiltration in dorsal skin of Skh-1 mice at the peak of the post-UVB inflammatory response. We found an increase in markers of inflammation caused by treatment with CsA, and a decrease in markers of inflammation with treatments of SRL and CsA+SRL. The next step was to examine continuously immunosuppressed mice concurrently exposed to UVB for 13 weeks, the point right before tumors begin to emerge. Again we found very similar changes in the skin. CsA treatment overall caused increases in markers of inflammation while SRL and CsA+SRL decreased them. To quantify the effect of these changes on tumor development, this same experiment was repeated, however, after 12 weeks of concurrent immunosuppression and UVB exposure all treatments were stopped and tumors were allowed to progress. We found that CsA caused larger and more aggressive tumors to develop while SRL did not significantly affect tumor size burden or grade and CsA+SRL resulted in reduced tumor burden. The CsA+SRL treatment group also developed the least number of malignant tumors. Finally, to determine the effects of these agents on the progression of tumors, mice were exposed to UVB for 15 weeks to induce tumor development then UVB was stopped and immunosuppression was begun. As in the previous experiments, CsA caused larger and more aggressive tumors to develop. This was associated with increases in innate immune mediators in the tumor microenvironment, such as mast cells and the cytokine TGFβ1, as well as increased DNA damage. Treatment with either SRL or CsA+SRL caused smaller less aggressive tumors to develop in association with a concomitant reduction in the same innate immune mediators. In light of research in our laboratory regarding the efficacy of celecoxib (CX) as an inhibitor of UVB induced inflammation and carcinogenesis, topical celecoxib was administered in combination with CsA+SRL to determine if a further reduction in inflammation and tumor development could be achieved. All four of the same experimental designs previously used were examined. We found that CX administered concurrently with CsA+SRL was able to further reduce markers of inflammation as well as tumor development but was not able to affect tumor progression as measured by histological grading. A preliminary experiment was conducted to determine the likelihood of a much newer immunosuppressive agent, leflunomide, having anti-inflammatory effects on acute UVB induced inflammation. We found that we could effectively obtain consistent and adequate levels of the active metabolite of leflunomide in the serum of our mice, however, other outcomes were quite varied and no definitive conclusions could be drawn concerning its effects on UVB-induced inflammation. Finally, the efficacy of topical treatment with a DNA repair enzyme, OGG1, was tested. We found that this liposome encapsulated enzyme could penetrate into the epidermis of our mice and reduce the levels of its DNA damage target, 8-hydroxy-deoxyguanine. This also translated into a reduction in tumor development. In conclusion the data in this thesis demonstrate that CsA and SRL differentially alter the acute and chronic inflammatory responses to UVB, as well as the cutaneous tumor microenvironment, which in turn contribute to enhanced and inhibited development of UVB-induced skin cancer, respectively, in a murine model of skin carcinogenesis. Furthermore, these data reveal that co-administration of CsA and SRL can lead to a reduced UVB-induced inflammatory response contributing to reduced skin cancer development and progression compared to either immunosuppressant alone. Further studies with these and other immunosuppressants need be conducted in order to develop immunosuppressive regimens that maintain strong graft function and minimize the risk of post transplant malignancies.

The vitamin D endocrine system plays important but inadequately understood roles in skin homeostasis. 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] is the biologically active ligand for the vitamin D receptor (VDR). VDR knockout (KO) mice lack a functional receptor, whereas ligand knockout mice lack 25-hydroxyvitamin-D3 1α-hydroxylase (1αOHase), the enzyme required for 1,25(OH)2D3 synthesis. VDRKO mice have a hair follicle cycling defect resulting in alopecia and high susceptibility to chemically induced skin tumorigenesis, whereas 1αOHaseKO mice have normal follicle function. These models indicate that VDR functions independently of 1,25(OH)2D3 in hair follicle cycling. The goal of this dissertation was to better understand the roles of VDR and 1,25(OH)2D3 in skin tumorigenesis and to elucidate how VDR activity is regulated in the skin. We demonstrate that 1αOHaseKO mice are resistant to chemically-induced tumorigenesis, indicating that 1,25(OH)2D3 is not required for tumor protection. We also show that VDR protects against ultraviolet light-induced skin tumorigenesis, the relevant cause of skin cancer in humans. Proliferation assays indicate that UV inhibits short-term growth of wildtype, but not VDRKO, keratinocytes. Thymine dimer immunoblots show that VDR promotes DNA repair, and TUNEL assays indicate that VDR facilitates UV-induced apoptosis. The differences between receptor and ligand knockout mice suggest that the actions of VDR and 1,25(OH)2D3 are uncoupled in the skin. Using reporter gene assays and RT-PCR, our research is the first to provide cell-based mechanistic evidence that VDR exerts activity in the absence of the 1,25(OH)2D3 ligand. The magnitude of 1,25(OH)2D3-independent VDR activity is on par with traditional, 1,25(OH)2D3-induced activity and occurs only in keratinocytes. Mammalian two-hybrid assays show that 1,25(OH)2D3-independent activity of VDR stems from strong interaction between VDR and its partner, the retinoid X receptor, and is potentiated by the epidermal growth factor signaling cascade. We also show that constitutively active forms of certain Ca2+/calmodulin-dependent kinases enhance 1,25(OH)2D3-mediated transcription by increasing phosphorylation of VDR, promoting interaction between VDR and coactivators, and increasing the intrinsic transcriptional activity of steroid receptor coactivators. Cumulatively, our studies support a novel, 1,25(OH)2D3-independent role for VDR in keratinocytes that may be potentially exploited as a pharmacological target to treat hyperproliferative skin diseases.

Foodborne illnesses caused by Listeria monocytogenes have long been associated with ready-to-eat (RTE) meats contaminated after the primary thermal process has been applied. It is believed that brine solutions used to chill cooked RTE products may serve as a reservoir for L. monocytogenes becoming a potential point of post-processing contamination for RTE meats. Re-circulating ultraviolet light (UV) systems are being used to inactivate L. monocytogenes in chill brines; however very little has been reported on the dose response of healthy and stressed L. monocytogenes to UV in brine solutions. The objectives of this research were to determine 1) minimum dose of UV required to inactivate L. monocytogenes in distilled water, fresh brine, undiluted spent brine, and diluted spent brine, 2) if adaptation to food processing stresses affects the dose response, and 3) if the acquisition of antibiotic resistance mechanisms provides resistance to ultraviolet light 4) effect of stress adaptation on survival in brine solutions. After UV exposure, populations were reduced as follows from greatest to least: water > fresh brine > 5% spent brine > 35% spent brine > 55% spent brine > 100% spent brine (P ≤ 0.05). There were no population differences between acid stressed and antibiotic resistant or healthy and heat shocked (P > 0.05). However, acid-stressed and sulfanilamide-resistant were more resistant to UV light than healthy and heat shocked L. monocytogenes (P ≤ 0.05). Survival in brine solutions (no UV) followed the trend, from greatest to least (P ≤ 0.05): sulfanilamide-resistant > acid-stressed > healthy > heat-shocked. Population estimates decreased from initial inoculation to final sampling for each cell type suspended in spent brine (P ≤ 0.05), but only healthy and heat- shocked cells suspended in fresh brine were significantly reduced (P ≤ 0.05). Knowledge of UV dosing required to control L. monocytogenes in brines used during RTE meat processing, and a greater understanding of the interactions that may influence dose will aid manufacturers in establishing appropriate food safety interventions for these products.

Chill brines used in ready-to-eat meat processing may be an important source of post-processing contamination by Listeria monocytogenes. The purpose of this study was to determine the efficacy of ultraviolet light (UV) in combination with antimicrobials to reduce L. monocytogenes in fresh and used chill brines. Three different antimicrobials were used in combination with UV; citric acid (CA, 0.2 and 0.5%), dimethyl dicarbonate (DMDC, 250 and 500 ppm), and hydrogen peroxide (HP, 2000 and 4000 ppm). For fresh brine studies, brine (8.0% w/v NaCl) was prepared and inoculated with a cocktail of three L. monocytogenes strains (approximately 6 log CFU/mL). Brine was treated with UV alone, antimicrobials alone, and combination of UV and antimicrobials. Moreover, to observe the effect of treatment temperature and brine circulation through the UV system on survival of listeriae cells, inoculated brine was circulated through the system without any treatment that served as control for all the treatments. For UV treatment, inoculated brine solution was exposed to UV in an Ultraviolet Water Treatment Unit (Model: AMD 150B/1/2T D; Aquionics Inc., Peak output: 254 nm) fitted with an inline chiller to maintain brine temperature of -1°C. Samples were withdrawn at regular intervals for 120 minutes. When L. monocytogenes population was no longer detectable via direct plating on MOX, enrichment was performed and suspect colonies were confirmed using API-Listeria. For antimicrobial-only (i.e., no UV) treatments, a specific concentration of antimicrobial was added in inoculated brine and samples were taken for 120 minutes. For the brine that received combination of UV and antimicrobial treatments, UV was turned on once a specific concentration of antimicrobial was added in inoculated brine and samples were withdrawn at regular intervals for 120 minutes. When treated with UV alone, L. monocytogenes population decreased from approximately 6 log CFU/mL to below the detection limit (i.e., 1 log CFU/mL) in 15 minutes with the reduction rate of 0.87 log CFU/mL per minute. However, cells were detectable by enrichment through 120 minutes. The highest rate of decline (0.90 log CFU/mL per minute) was achieved by the combination of UV and 500 ppm DMDC (UV+500 ppm DMDC), which was not significantly different from the reduction rates of UV and UV+0.5% CA. UV+500 ppm DMDC reduced L. monocytogenes to the detection limit in 15 minutes and the organism was not detected by enrichment after 60 minutes. Though the reduction rate of UV+0.5% CA was not significantly lower than the rate of UV+500 ppm DMDC (P>0.05), the former treatment resulted in non-detectable levels more quickly (45 minutes) than the latter (60 minutes). Thus, based on enrichment studies UV+0.5% CA was the most effective treatment in reducing the population of L. monocytogenes in fresh brine. Moreover, when brine was treated with 0.5% CA alone the population decreased to below detection limit in 15 minutes with the rate significantly lower than UV+500 ppm DMDC and UV+0.5% CA (P

Non-melanoma skin cancer is the most prevalent form of cancer. The incidence of basal cell carcinoma is 2X higher and squamous cell carcinoma is 3X higher in males compared to females. Exposure to UVB is the primary agent responsible for the formation of NMSCs. While it is well documented that males spend more time out in the sun and use less sun protective measures, the potential of a biological contribution to these gender differences had not been previously evaluated. We therefore investigated the gender differences in the acute UVB induced inflammatory response and chronic UVB induced tumor formation in the hairless Skh-1 mouse model. Our studies demonstrated that acute exposure to UVB induced a cutaneous inflammatory response in both the male and female mice, however, the response was markedly lower in the males. After chronic exposure to UVB, the male mice exhibited enhanced carcinogenesis as they developed tumors earlier, developed more tumors, and developed larger tumors. Overall males had twice the tumor burden and more aggressive tumors. Interestingly, with the limited inflammatory response, the males exhibited elevated oxidative DNA damage and a limited antioxidant capacity allowing for more oxidative stress induced DNA damage. There is evidence that estrogen may convey a protective effect on the female gender. Topical estrogen decreased the acute inflammatory response in the female mice, yet enhanced the response in the males. Estrogen enhanced tumor multiplicity and tumor burden in the female mice, however, the tumors in both genders were less aggressive. Topical treatment with Faslodex, a complete anti-estrogen, increased tumor size in both genders and the tumors were more aggressive. Due to the gender differences in baseline antioxidant capacity, we examined the activity of catalase, glutathione peroxidase, glutathione reductase and glutathione s-transferase in the skin. These studies demonstrated that multiple enzymes contribute to the baseline differences in activity and the response to UVB exposure is gender, enzyme, and time dependent. These studies suggest that insufficient antioxidant capacity in the male mice contributes greatly to their enhanced carcinogenic potential and that topical antioxidants may be more effective at treating and preventing skin cancer in the male population.

Ready-to-eat meat products have been implicated in several foodborne listeriosis outbreaks. Microbial contamination of these products can occur after the product has been thermally processed and is being rapidly chilled using salt brines. The objective of this study was to determine the effect of ultraviolet irradiation on the inactivation of Listeria monocytogenes and lactic acid bacteria in a model brine chiller system. Two concentrations of brines (7.9%w/w or 13.2%w/w) were inoculated with a ~6.0 log10 CFU/ml cocktail of L. monocytogenes or lactic acid bacteria and passed through the ultraviolet (UV) treatment system for 60 minutes. Three replications of each bacteria and brine combination were performed and resulted in at least a 4.5 log reduction in microbial numbers in all treated brines after exposure to ultraviolet light. Bacterial populations were significantly reduced after five minutes exposure to UV light in the model brine chiller as compared to the control, which received no UV light exposure (P

Two studies investigating the use ultraviolet light at a wavelength of 253.7nm (UVC) into the inhibition of Salmonella spp. and Escherichia coli O157:H7 were conducted. The objectives of these studies were: to determine the rates for the destruction of Salmonella and Escherichia coli O157:H7 on the surface of agar and to investigate its effectiveness on the surface of fresh produce. Multiple replications of different doses and cocktail concentrations were performed and resulted in a 5 log reduction of Escherichia coli O157:H7 at doses exceeding 8.4 mW / cm2, while a 5 log reduction for Salmonella spp. was observed at doses exceeding 14.5 mW / cm². Samples of Red Delicious apples, green leaf lettuce and tomatoes were subjected to different doses ranging from 1.5 __ 24 mW / cm2 of UVC to determine effective log reductions of microbial populations. UVC applied to apples inoculated with E. coli O157:H7 resulted in the highest log reductions of approximately 3.3 logs at 24 mW/cm2. Lower log reductions (2.19 logs) were seen on tomatoes inoculated with Salmonella spp. and leaf lettuce (2.65 and 2.79) inoculated with both Salmonella spp. and E. coli O157:H7 respectfully. Due to the low capital involved in initiating a UVC system, the use of ultraviolet energy may prove to be a beneficial mechanism to decrease pathogens on fresh produce if used in conjunction with strict adherence to a sanitation program, Good Manufacturing Practices and Good Agricultural Practices in ensuring the safety of fresh produce.

This research investigated the efficacy of chlorine dioxide (ClO₂), ultraviolet (UV) irradiation, UV in combination with chlorine dioxide (UV/ClO₂), and UV in combination with hydrogen peroxide (UV/H₂O₂) for decolorizing three reactive azo dyes (sultan red, indigo blue and cypress green) and treated textile-manufacturing wastewater. The objective was to determine the best treatment for reducing color to the Virginia Pollutant Discharge Elimination System (VPDES) permit level of 300 American Dye Manufacturers Institute (ADMI) units. The effects of the three chemical oxidation treatments provided color reduction for all three dyes. The results suggested UV/H₂O₂ and UV/ClO₂2 treatments provided maximum color reduction of the red and blue dyes, and UV/H₂O₂ was the most effective for maximum reduction of the green dye. A research goal was to provide predictive models of the wastewater effluent for the treatment processes, including the UV exposure time required to reach the 300 ADMI permit value and the effective ClO₂ dose necessary to achieve the 300 units. The results of the investigations regarding the effluent indicated that UV/H₂O₂ and UV/ClO₂ (5 mg/L) provided reduction to 300 units in less than 10 minutes UV exposure when the initial effluent color was less than 500 ADMI units. Without the addition of oxidant, contact times longer than 10 minutes were required for UV to decolorize these effluents to 300 ADMI units. Chlorine dioxide dosages between 10 and 30 mg/L both with and without UV irradiation achieved the same results.

Three studies regarding Escherichia coli O157:H7 in apple cider were conducted. The objectives were: to evaluate the effectiveness of wash and sanitizers for removing E. coli O157:H7 from apples; to survey cider producer practices; and to determine the efficacy of ultraviolet light for reducing E. coli O157:H7 in cider. Apples with a five-strain acid resistant mixture of E. coli O157:H7 were treated with 200 ppm hypochlorite, a phosphoric acid-based fruit wash, 5% acetic acid, 5% acetic acid followed by 3% hydrogen peroxide, a peroxyacetic acid-based solution, and distilled water. The water wash caused insignificant reductions. All other treatments caused significant reductions. Acetic acid and peroxyacetic acid were the most effective with reductions of 3.1 and 2.6 logs, respectively. The survey determined that most producers are small, seasonal operations. Most use sound orchard management practices, clean and sanitize daily, sort and wash apples, use refrigeration, and try to prevent contamination. However, some use drop and damaged apples. Few use chemical sanitizers on apples, preservatives, pasteurize cider, or have HACCP programs. Cider inoculated with the same mixture of E. coli O157:H7 was processed using a thin- film ultraviolet disinfection unit operating at 254 nm. Dosages ranged from 9,402 to 61,005 æW- sec/cm2. Treatment significantly reduced E. coli O157:H7 (pó 0.0001) with a mean reduction of 3.81 log CFU/ml. Reduction was also affected by the level of background microflora in cider. Results indicate that ultraviolet light can reduce this pathogen in cider. However, additional reduction measures are necessary to achieve the required 5 log reduction.

The problem was to study several hydrocarbons when they were subjected to ultraviolet light of 2536 Å in the presence of mercury vapor. It would be expected from the work of Stallings that the rupture of any tertiary hydrogen bond in the molecule would be the predominant effect. However, secondary and primary bond splitting would occur as well as some C-C bond rupturing, but these could be expected to a lesser degree than the first, since the t-hydrogen has the greatest reactivity.

The problem was to study the behavior of several hydrocarbons when they were subjected to ultraviolet light of 2536 Å in the presence of mercury vapor.