Master of Science / Department of Grain Science and Industry / Cassandra Jones / Salmonella contamination in animal food production facilities is a growing concern. The bacteria has been the cause of 40% of pet food recalls in the past 5 years, and there are potential human health implications because pet food is a direct human contact food. A potential method to reduce Salmonella contamination in pet food is through the use of acidifiers and desiccants to destroy and inhibit growth of bacteria. The objective of this thesis was to quantify Salmonella contamination in livestock feed and pet food manufacturing facilities, and propose mitigation measures to mitigate the presence of pathogens in animal food. Therefore, the objective of Experiment 1 was to investigate sources of Salmonella contamination throughout livestock feed (n = 2) and pet food (n = 2) manufacturing facilities on a specific sampling day. Salmonella was present in all four facilities. However, one of the livestock feed manufacturing facilities had more than double the Salmonella-positive locations than all other facilities. This experiment demonstrated that surface type and location should be taken into consideration when controlling Salmonella contamination. In Experiments 2 and 3, the use of a commercial powdered dry acidulant, sodium bisulfate, was studied as a coating of dog kibble to reduce and prevent Salmonella growth over time. The coating reduced Salmonella concentration, and its efficacy was not impacted by altering the bulk density or surface area of the kibble. Experiment 4 was conducted to determine the efficacy of sodium bisulfate added to poultry mash to reduce or prevent Salmonella growth over time. The inclusion of the dry acidulant did not reduce Salmonella concentration; however, storage time reduced Salmonella contamination in poultry feed. In summary, Salmonella contamination exists in manufacturing facilities, but the location and magnitude of contamination differs. Furthermore, sodium bisulfate effectively reduces Salmonella contamination when applied as a pet food coating, but not in poultry feed.

Ammonia (NH₃) emissions from animal manure, such as poultry litter, can cause air quality problems. These emissions also result in excessive nitrogen (N) loading into aquatic environments which can lead to water quality problems where N is the limiting nutrient for eutrophication, such as the Chesapeake Bay. Poultry litter treatment (PLT, sodium bisulfate) is an acidic amendment that is applied to litter in poultry houses to decrease NH3 emissions, but currently it can only be applied before birds are placed in the houses. This project analyzed the effect of multiple PLT applications on litter properties and NH₃ release in a controlled and field environment. Volatility chambers with acid traps were used to compare multiple, single, and no applications of PLT to poultry litter. Both single and reapplied PLT caused a greater moisture content and lower pH in litter. Additionally, the E.coli in litter was decreased significantly with both single and reapplied PLT. After 15 days, NH₃ released from litter treated with reapplied PLT was significantly less than litter with both single and no applications. Furthermore, NH₄⁺-N content of litter was greatest in litter treated with reapplied PLT increasing its fertilizer value. The efficacy of a new farm scale system capable of applying several additions of PLT to poultry litter throughout the growth of a flock was also evaluated. Though litter pH, E.coli, and NH₃ volatilization were temporarily decreased with PLT application, the overhead reapplication auger system is not recommended at this time due to moisture and corrosion problems. / Ph. D.

Master of Science / Food Science Institute / Sara E. Gragg / Leafy greens have been recognized as vehicles for transmission of foodborne pathogens and an effective pre-harvest intervention to control them is currently lacking. After harvest, lettuce is often subjected to chlorinated water to reduce the microbial load in the water and on the lettuce tissue. While moderately effective, there is also a need for improved postharvest interventions. The purpose of Objective I was to 1) determine potassium bisulfate efficacy at reducing populations of Escherichia coli (E. coli) and Listeria innocua (L. innocua) when applied pre-harvest to lettuce, and 2) assess the impact on product quality at harvest. Potassium bisulfate reduced E. coli populations on inoculated lettuce by 1.32 log₁₀ CFU/g (P=0.0002) and L. innocua by 1.18 log₁₀ CFU/g (P=0.0017). No detectable differences were observed in color (P>0.05); however, brown spots were observed on various leaves sprayed with potassium bisulfate. The purpose of Objective II was to employ a blend of benzalkonium chloride, acetic acid, and methyl paraben (BAM) as a postharvest wash on romaine and iceberg lettuce and to 1) determine efficacy at reducing populations of Listeria monocytogenes (L. monocytogenes), E. coli O157:H7 and Salmonella, 2) measure changes in aerobic bacteria throughout the shelf life, and 3) quantify benzalkonium chloride and methyl paraben residues post-washing. To quantify efficacy of BAM reducing pathogenic bacterial populations, fresh-cut romaine and iceberg lettuce were inoculated with L. monocytogenes, E. coli O157:H7, or Salmonella and washed in BAM at concentrations of 0%, 1%, 2% or 3% for one or five minutes. When plated on recovery media, contact time and wash concentration was not significant (P>0.05) for Salmonella on either product. Concentration was significant (P=0.0189) for L. monocytogenes on romaine; however, the greatest reduction observed was <1.0 log₁₀ CFU/g. The 3% wash significantly reduced E. coli O157:H7 on romaine by 1.75 log₁₀ CFU/g, which is 0.66 log₁₀ CFU/g better than the 0% wash. Following washing, wash water was analyzed and data demonstrate that all wash concentrations significantly (P≤0.05) reduced each foodborne pathogen by >2.0 log₁₀ CFU/g in the wash water. To quantify benzalkonium chloride and methyl paraben residues, as well as changes in aerobic bacteria and product quality, fresh-cut romaine and iceberg lettuce were subjected to a 1 minute wash in BAM at concentrations of 0%, 1%, 2%, or 3% and immediately sampled to determine aerobic populations and product quality. Concentrations 0% and 2% were also packaged into retail storage bags and sampled on days 0, 3, 5, and 7. Residues were quantified on these days as well. On day 0, aerobic populations did not vary according to wash concentration (P>0.05). With regards to shelf-life data, the 2% wash significantly reduced (P=0.0203) aerobic bacteria on romaine lettuce; however, no significant difference was observed on iceberg lettuce (P=0.0819). With regards to overall visual appearance of romaine or iceberg lettuce, no significant difference was detected between 0% and 2% BAM washes for each day throughout the shelf-life study (P>0.05). Methyl paraben and benzalkonium chloride residues were <5.0 and <10.0 ppm, respectively, on both products on each sampling day.

No description available.

Polarized Raman spectroscopy has been used to measure the deuterium isotope effect, (delta)pK = pKD2O – pKH2O, for the second ionization constant of sulfuric acid in the temperature range of 25 °C to 200 °C at saturation pressure. Results for pK in light water agree with the literature within ± 0.034 pK units at alltemperatures under study, confirming the reliability of the method. The ionization constant of deuterated bisulfate, DSO4-, differs significantly from previous literature results at elevated temperatures. This results in an almost constant (delta)pK ≈ 0.425 ± 0.076 over the temperature range under study. Differences in (delta)pK values between the literature and current results can be attributed to the effect of dissolved silica from cell components. The new results are consistent with (delta)pK models that treat the temperature dependence of (delta)pK by considering differences in the zero-point energy of hydrogen bonds in the hydrated product and reactant species. The phosphate hydrolysis equilibrium was measured between the temperatures of 5 °C and 80 °C and the borate/boric acid equilibrium between the temperatures of 25 °C and 200 °C. The high alkalinity and temperatures experienced by these two systems had a significant impact on the glass dissolution and equilibrium. / Raman spectroscopy was used to measure the small differences in ionization constants for weak acids/bases as a function of temperature. / University of Guelph, Atomic Energy of Canada Limited (AECL), Bruce Power, University Network of Excellence in Nuclear Engineering (UNENE), National Sciences and Engineering Research Council of Canada (NSERC), Natural Resources Canada, Ontario Power Generation (OPG), Canada Foundation for Innovation

The master thesis deals with possibilities of utilization of conventional power plant fly ash after introduction of SNCR (Selective non-catalytic reduction) as a method of flue gas denitrification. Behaviour of fly ash containing products of denitrification, ash with water and stabilizate prepared from contaminated ash was studied. Experiments were focused on the study of various factors affecting the release of ammonia from prepared mixtures. Samples were exposed to the weather conditions to simulate deposition in addition to the laboratory experiment. Influence of the fly ash containing denitrification to mechanical properties and volume stability of pastes and mortars were also studied. The interaction of denitrification products with superplasticizers was studied on pastes. Achieved results were verified on concretes.

The objective of this study was to increase the bond strength at the surface interface of a thin stainless-steel panel for structural bonding on a helicopter. To achieve this objective, six activation methods for applying the coating to the panel in the surface preparation process are presented and explored. Adhesion and roughness tests were conducted to determine which method consistently initiates the etch and improves the bond at the surface. Based on the test results, three methods proved to be effective in initiating the etch. Of the three effective methods, only one method exhibited significantly improved bond strength at the surface interface as well as consistently initiated the etch in solution. The applicability of this method is discussed, and recommendations are presented for further study.

The thesis entitled “Towards the Design of Functional Materials: Evaluation based on Crystal Structure, Photocatalysis and Conductivity Measurements” consist of six chapters. A short introductory note outlines the basis of designing functional materials, different synthetic procedures, characterization techniques and properties such as photocatalysis and ionic conductivity. Chapter 1 describes the effect of Ti doping on photocatalytic activity in orthorhombic perovskite type LnVO3. All the compounds were synthesized by solid state method. Rietveld refinement with high resolution PXRD reveals that the substituent Ti occupies V site rather than Ln Site. Ti substituted compound showed higher photocatalytic activity than the unsubstituted compound and is comparable with that of commercial catalyst. These classes of compounds showed specific degradation towards chlorinated compounds. Chapter 2 discusses the solution combustion synthesis of γ(L)-Bi2MoO6 and its photocatalytic activity under solar radiation. The particle sizes were in the range 300–500 nm with a band gap of 2.51 eV. The degradation of wide variety of cationic and anionic dyes was investigated under solar radiation. Despite the low surface area (<1 m2/g), γ(L)-Bi2MoO6 showed higher photocatalytic activity under solar radiation due to its electronic and morphological properties. Chapter 3 presents a series of visible light photocatalyst M2Ce2O7, synthesized via solution combustion method and characterized by powder X-ray diffraction, solid-state UV-Visible diffuse reflectance spectra, SEM and TEM. The structure of Bi2Ce2O7 has been determined using laboratory as well as synchrotron PXRD. It crystallizes in a disordered F-type structure. The particle sizes are in the range 5–6 nm, band gaps lie within the range 1.7 to 3.2 eV. Bi2Ce2O7 shows high photocatalytic activity, comparable to the commercial Degussa P-25 TiO2 under solar radiation. Chapter 4 examines the effect of Bismuth substitution on crystal chemistry, photocatalysis and conductivity in Sr3V2O8, a variant of palmierite class. These compounds were synthesized by ceramic method and powder X-ray data reveals the limit of the Bi substitution in Sr3-xBi2x/3V2O8 is x=0.4. Single crystal study followed by careful difference Fourier analysis shows that Bi occupies a unique 18h position which is different than Sr1 and Sr2 position. The experimental band gap for Sr3V2O8 was calculated to be 3.45 eV and upon substitution band gap of the material decreases and reaches a value 3.15 eV for the composition x=0.4. Compound exhibits photocatalytic activity specifically towards anionic dyes. However, Bi Substitution leads to lower photocatalytic activity. Chapter 5 describes synthesis, structure, phase transition and ionic conductivity in scheelite type Li0.5Ce0.5MoO4. The compound was synthesized by ceramic method and single crystal study reveals that it crystallizes in the space group I41/a and exhibits conductivity of ~10-3 Ohm-1cm-1 at elevated temperature( 700 °C). It undergoes a first order phase transition around 510 °C. The nature of this transition has been evaluated by laboratory and synchrotron PXRD, DSC, dielectric spectroscopy and variable temperature Raman spectroscopy. The phase transition is shown to be characterized by an iso-structural phase transition which is first example in literature for temperature induced Cowley’s “Type Zero” phase transition. Chapter 6 discusses a new methodology for generating functional materials for fast ion conductors. Several varients of hydrated sodium cadmium bisulfate, Na2Cd2(SO4)3⋅3H2O, Na2Cd(SO4)2⋅2H2O and Na2Cd(SO4)2⋅4H2O have been synthesized and their thermal properties followed by phase transitions have been invesigated. Na2Cd2(SO4)3⋅3H2O (space group P3c). Na2Cd2(SO4)3⋅3H2O loses water completely when heated to 250 °C and transforms to a dehydrated phase (I⎯43d ) whose structure has been established using abinitio powder diffration techniques. Na2Cd(SO4)2⋅2H2O (P21/c) transforms to α−Na2Cd(SO4)2 (space group C2/c) on heating to 150 °C which is a known high ionic conductor. However, when α−Na2Cd(SO4)2 is heated to 570 °C followed by sudden quenching in liquid nitrogen, β−Na2Cd(SO4)2 (P21/c) is formed. β−Na2Cd(SO4)2 takes up water from the atmosphere and gets converted completely to the Kröhnkite type mineral. Further, β−Na2Cd(SO4)2 has a conductivity behavior comparable to α form up to 280 °C, the temperature required for the transformation of β to α form.